U.S. patent application number 12/326311 was filed with the patent office on 2009-06-25 for carbazole derivative, and light-emitting element, light-emitting device, and electronic device using carbazole derivative.
This patent application is currently assigned to Semiconductor Energy Laboratory Co., Ltd.. Invention is credited to Sachiko Kawakami, Hiroko Nomura, Harue Osaka, Satoshi Seo, Satoko Shitagaki, Takahiro Ushikubo.
Application Number | 20090160323 12/326311 |
Document ID | / |
Family ID | 40717765 |
Filed Date | 2009-06-25 |
United States Patent
Application |
20090160323 |
Kind Code |
A1 |
Nomura; Hiroko ; et
al. |
June 25, 2009 |
Carbazole Derivative, and Light-Emitting Element, Light-Emitting
Device, and Electronic Device Using Carbazole Derivative
Abstract
To provide a light-emitting element having high luminous
efficiency and to provide a light-emitting device and an electronic
device which consumes low power and is driven at low voltage, a
carbazole derivative represented by the general formula (1) is
provided. In the formula, .alpha..sup.1, .alpha..sup.2,
.alpha..sup.3, and .alpha..sup.4 each represent an arylene group
having less than or equal to 13 carbon atoms; Ar.sup.1 and Ar.sup.2
each represent an aryl group having less than or equal to 13 carbon
atoms; R.sup.1 represents any of a hydrogen atom, an alkyl group
having 1 to 6 carbon atoms, a substituted or unsubstituted phenyl
group, and a substituted or unsubstituted biphenyl group; and
R.sup.2 represents any of an alkyl group having 1 to 6 carbon
atoms, a substituted or unsubstituted phenyl group, and a
substituted or unsubstituted biphenyl group. In addition, l, m, and
n are each independently 0 or 1.
Inventors: |
Nomura; Hiroko; (Isehara,
JP) ; Osaka; Harue; (Sagamihara, JP) ;
Ushikubo; Takahiro; (Atsugi, JP) ; Kawakami;
Sachiko; (Atsugi, JP) ; Seo; Satoshi;
(Kawasaki, JP) ; Shitagaki; Satoko; (Isehara,
JP) |
Correspondence
Address: |
COOK ALEX LTD
SUITE 2850, 200 WEST ADAMS STREET
CHICAGO
IL
60606
US
|
Assignee: |
Semiconductor Energy Laboratory
Co., Ltd.
|
Family ID: |
40717765 |
Appl. No.: |
12/326311 |
Filed: |
December 2, 2008 |
Current U.S.
Class: |
313/504 ;
548/440 |
Current CPC
Class: |
C07D 209/86 20130101;
H01L 51/0061 20130101; H01L 51/006 20130101; H01L 51/0072
20130101 |
Class at
Publication: |
313/504 ;
548/440 |
International
Class: |
H01J 1/63 20060101
H01J001/63; C07D 209/86 20060101 C07D209/86 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 3, 2007 |
JP |
2007-312509 |
May 16, 2008 |
JP |
2008-129917 |
Claims
1. A carbazole derivative represented by a general formula (1),
##STR00203## wherein .alpha..sup.1, .alpha..sup.2, .alpha..sup.3,
and .alpha..sup.4 each represent an arylene group having less than
or equal to 13 carbon atoms, wherein Ar.sup.1 and Ar.sup.2 each
represent an aryl group having less than or equal to 13 carbon
atoms, wherein R.sup.1 represents any of a hydrogen atom, an alkyl
group having 1 to 6 carbon atoms, a substituted or unsubstituted
phenyl group, and a substituted or unsubstituted biphenyl group,
wherein R.sup.2 represents any of an alkyl group having 1 to 6
carbon atoms, a substituted or unsubstituted phenyl group, and a
substituted or unsubstituted biphenyl group, and wherein l, m, and
n are each independently 0 or 1.
2. A carbazole derivative according to claim 1, wherein
.alpha..sup.1 to .alpha..sup.4 in the general formula (1) are
represented by any of general formulas (2-1) to (2-12),
##STR00204## ##STR00205## wherein R.sup.11 to R.sup.16, R.sup.21 to
R.sup.30, R.sup.31 to R.sup.38, and R.sup.41 to R.sup.45 each
represent any of a hydrogen atom, an alkyl group having 1 to 6
carbon atoms, a phenyl group, and a biphenyl group, wherein
R.sup.46 and R.sup.47 each represent any of an alkyl group having 1
to 6 carbon atoms and a phenyl group, and wherein R.sup.48
represents any of a hydrogen atom, an alkyl group having 1 to 6
carbon atoms, a phenyl group, and a biphenyl group.
3. A carbazole derivative according to claim 2, wherein R.sup.46
and R.sup.47 are connected to each other.
4. A carbazole derivative according to any one of claims 1 to 3,
wherein Ar.sup.1 and Ar.sup.2 in the general formula (1) are
represented by any of general formulas (3-1) to (3-6), ##STR00206##
wherein R to R.sup.56, R.sup.61 to R.sup.70, R.sup.71 to R.sup.81
and R.sup.85 to R.sup.85 each represent any of a hydrogen atom, an
alkyl group having 1 to 6 carbon atoms, a phenyl group, and a
biphenyl group, wherein R.sup.86 and R.sup.87 each represent any of
an alkyl group having 1 to 6 carbon atoms and a phenyl group, and
wherein R.sup.88 and R.sup.89 each represent any of a hydrogen
atom, an alkyl group having 1 to 6 carbon atoms, a phenyl group,
and a biphenyl group.
5. A carbazole derivative according to claim 4, wherein R.sup.86
and R.sup.87 are connected to each other.
6. A carbazole derivative according to any one of claims 1 to 3,
wherein R.sup.1 in the general formula (1) are represented by any
of general formulas (4-1) to (4-9) and R.sup.2 in the general
formula (1) is represented by any of the general formulas (4-2) to
(4-9), ##STR00207## wherein R.sup.51 to R.sup.70 each represent any
of a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a
phenyl group, and a biphenyl group.
7. The carbazole derivative according to claim 1, wherein the
carbazole derivative is represented by a structural formula (5).
##STR00208##
8. The carbazole derivative according to claim 1, wherein the
carbazole derivative is represented by a structural formula (6).
##STR00209##
9. The carbazole derivative according to claim 1, wherein the
carbazole derivative is represented by a structural formula (7).
##STR00210##
10. The carbazole derivative according to claim 1, wherein the
carbazole derivative is represented by a structural formula (8).
##STR00211##
11. A light-emitting element comprising: a pair of electrodes; and
an EL layer containing a carbazole derivative, wherein the
carbazole derivative is represented by a general formula (1),
##STR00212## wherein .alpha..sup.1, .alpha..sup.2, .alpha..sup.3,
and .alpha..sup.4 each represent an arylene group having less than
or equal to 13 carbon atoms, wherein Ar.sup.1 and Ar.sup.2 each
represent an aryl group having less than or equal to 13 carbon
atoms, wherein R.sup.1 represents any of a hydrogen atom, an alkyl
group having 1 to 6 carbon atoms, a substituted or unsubstituted
phenyl group, and a substituted or unsubstituted biphenyl group,
wherein R.sup.2 represents any of an alkyl group having 1 to 6
carbon atoms, a substituted or unsubstituted phenyl group, and a
substituted or unsubstituted biphenyl group, and wherein l, m, and
n are each independently 0 or 1.
12. The light-emitting element according to claim 11, wherein the
EL layer at least includes a light-emitting layer and a
hole-transporting layer, and wherein the carbazole derivative is
contained in the hole-transporting layer.
13. The light-emitting element according to claim 11, wherein the
pair of electrodes consist of an anode and a cathode, wherein the
EL layer at least includes a light-emitting layer, a
hole-transporting layer, and a hole-injecting layer, wherein the
hole-injecting layer is formed in contact with the anode, and
wherein the carbazole derivative is contained in the hole-injecting
layer.
14. The light-emitting element according to claim 13, wherein an
inorganic compound which exhibits an electron-accepting property
with respect to the carbazole derivative are further contained in
the hole-injecting layer.
15. The light-emitting element according to claim 14, wherein the
inorganic compound is an oxide of a transition metal.
16. The light-emitting element according to claim 14 or 15, wherein
the inorganic compound is one or more kinds of titanium oxide,
vanadium oxide, molybdenum oxide, tungsten oxide, rhenium oxide,
ruthenium oxide, chromium oxide, zirconium oxide, hafnium oxide,
tantalum oxide, and silver oxide.
17. A light-emitting device formed using the light-emitting element
according to any one of claims 11 to 15.
18. An electronic device formed using the light-emitting device
according to claim 17.
Description
TECHNICAL FIELD
[0001] The present invention relates to a carbazole derivative, a
light-emitting element, a light-emitting device, and an electronic
device using a carbazole derivative.
BACKGROUND ART
[0002] In recent years, light-emitting elements using
electroluminescence have been actively researched and developed. As
a basic structure of these light-emitting elements, a layer
containing a light-emitting substance is interposed between a pair
of electrodes. By applying voltage to this element, light emission
can be obtained from the light-emitting substance.
[0003] Since such a light-emitting element is a self-luminous type,
it has advantages over a liquid crystal display element, such as
high visibility of the pixels and no need of backlight and is
considered suitable for a flat panel display element. In addition,
such a light-emitting element can be manufactured to be thin and
light-weight, which is also a great advantage. Further, extremely
high response speed is also a feature thereof.
[0004] Furthermore, since such a light-emitting element can be
formed into a film form, planar light emission can be easily
obtained by forming a large-area element. It is difficult to obtain
this characteristic by using a point light source typified by an
incandescent lamp or an LED or by using a line light source
typified by a fluorescent lamp. Therefore, the light-emitting
element described above also has a high utility value as a planar
light source which is applicable to lighting or the like.
[0005] Such light-emitting elements using electroluminescence are
broadly classified according to whether a light-emitting substance
is an organic compound or an inorganic compound. When an organic
compound is used for a light-emitting substance, electrons and
holes are injected into a layer containing a light-emitting organic
compound from a pair of electrodes by applying voltage to a
light-emitting element, and then a current flows therethrough.
Then, by recombination of these carriers (electrons and holes), the
light-emitting organic compound forms an excited state, and emits
light when the excited state returns to a ground state.
[0006] With such a mechanism, such a light-emitting element is
referred to as a current-excitation light-emitting element. Note
that an excited state of an organic compound can be a singlet
excited state or a triplet excited state. Light emission from the
singlet excited state is referred to as fluorescence, and light
emission from the triplet excited state is referred to as
phosphorescence.
[0007] In improving element characteristics of such a
light-emitting element, there are a lot of problems which depend on
a substance, and in order to solve the problems, improvement of an
element structure, development of a substance, and the like have
been carried out (e.g., Non-Patent Document 1: Meng-Huan Ho,
Yao-Shan Wu and Chin H. Chen, 2005 SID International Symposium
Digest of Technical Papers, Vol. XXXVI. pp. 802-805).
[0008] In the light-emitting element described in Non-Patent
Document 1, 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl
(abbreviation: NPB) is used as a layer in contact with a
light-emitting layer. However, NPB has low singlet excitation
energy, and there is a possibility that the energy might be
transferred from the light-emitting material in the excited state.
Since the energy level of an excited state is particularly high in
the case of a light-emitting material which emits blue light having
a short wavelength, there is a higher possibility that the energy
is transferred to NPB. There has been a problem that luminous
efficiency of the light-emitting element is lowered due to transfer
of the energy to NPB.
DISCLOSURE OF THE INVENTION
[0009] Thus, it is an object of the present invention to provide a
light-emitting element having high luminous efficiency by providing
a novel carbazole derivative. Further, it is another object of the
present invention to provide a light-emitting device and an
electronic device which consumes low power and is driven at low
voltage.
[0010] One feature of the present invention is a carbazole
derivative represented by the following general formula (1).
##STR00001##
In the formula, .alpha..sup.1, .alpha..sup.2, .alpha..sup.3, and
.alpha..sup.4 each represent an arylene group having less than or
equal to 13 carbon atoms, which forms a ring; Ar.sup.1 and Ar.sup.2
each represent an aryl group having less than or equal to 13 carbon
atoms, which forms a ring; R.sup.1 represents any of a hydrogen
atom, an alkyl group having 1 to 6 carbon atoms, a substituted or
unsubstituted phenyl group, and a substituted or unsubstituted
biphenyl group; and R.sup.2 represents any of an alkyl group having
1 to 6 carbon atoms, a substituted or unsubstituted phenyl group,
and a substituted or unsubstituted biphenyl group. In addition, l,
m, and n are each independent, which is 0 or 1.
[0011] In addition, in the above structure, .alpha..sup.1 to
.alpha..sup.4 in the general formula (1) are represented by any of
the following general formulas (2-1) to (2-12).
##STR00002## ##STR00003##
[0012] In the formula, R.sup.1 to R.sup.16, R.sup.21 to R.sup.30,
R.sup.31 to R.sup.38, and R.sup.41 to R.sup.45 each represent any
of a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a
phenyl group, and a biphenyl group. R.sup.46 and R.sup.47 each
represent any of an alkyl group having 1 to 6 carbon atoms and a
phenyl group. In addition, R.sup.46 and R.sup.47 may be connected
to each other to form a ring. R.sup.48 represents any of a hydrogen
atom, an alkyl group having 1 to 6 carbon atoms, a phenyl group,
and a biphenyl group.
[0013] In addition, in the above structure, Ar.sup.1 and Ar.sup.2
in the general formula (1) are represented by any of the following
general formulas (3-1) to (3-6).
##STR00004##
In the formula, R.sup.51 to R.sup.56, R.sup.61 to R.sup.70,
R.sup.71 to R.sup.78, and R.sup.81 to R.sup.85 each represent any
of a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a
phenyl group, and a biphenyl group. R.sup.86 and R.sup.87 each
represent any of an alkyl group having 1 to 6 carbon atoms and a
phenyl group. In addition, R.sup.86 and R.sup.87 may be connected
to each other to form a ring. R.sup.88 and R.sup.89 each represent
any of a hydrogen atom, an alkyl group having 1 to 6 carbon atoms,
a phenyl group, and a biphenyl group.
[0014] Further, in the above structure, R.sup.1 in the general
formula (1) is represented by any of the following general formulas
(4-1) to (4-9), and R.sup.2 in the general formula (1) is
represented by any of the following general formulas (4-2) to
(4-9).
##STR00005##
In the formula, R.sup.51 to R.sup.70 each represent any of a
hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a phenyl
group, and a biphenyl group.
[0015] In addition, one feature of the present invention is
represented by any of the following structural formulas (5) to
(8).
##STR00006## ##STR00007##
[0016] In addition, as another feature of the present invention, a
light-emitting element includes an EL layer between a pair of
electrodes, the EL layer includes at least a light-emitting layer
and a hole-transporting layer, and at least one of the
light-emitting layer and the hole-transporting layer contains any
of the carbazole derivatives described above.
[0017] Further, as another feature of the present invention, a
light-emitting element includes an EL layer between an anode and a
cathode, the EL layer includes at least a light-emitting layer, a
hole-transporting layer, and a hole-injecting layer, the
hole-injecting layer is formed in contact with the anode, and at
least one of the light-emitting layer, the hole-transporting layer,
and the hole-injecting layer contains any of the carbazole
derivatives described above.
[0018] In addition, in the above structure, a structure may be
employed in which the hole-injecting layer contains any of the
carbazole derivatives described above and an inorganic compound
which exhibits an electron-accepting property with respect to the
carbazole derivative. Note that as the inorganic compound, an oxide
of a transition metal can be used. Further, as the inorganic
compound, one or more kinds of titanium oxide, vanadium oxide,
molybdenum oxide, tungsten oxide, rhenium oxide, ruthenium oxide,
chromium oxide, zirconium oxide, hafnium oxide, tantalum oxide, and
silver oxide can be used.
[0019] Further, as another feature of the present invention, a
light-emitting device is formed using any of the light-emitting
elements described above, and an electronic device is formed using
the light-emitting device.
[0020] Further, the present invention also includes a
light-emitting device having the light-emitting element described
above and an electronic device having the light-emitting device. A
light-emitting device in this specification refers to an image
display device, a light-emitting device, or a light source
(including a lighting device). In addition, light-emitting devices
include all of the following modules: modules in which a connector,
for example, a flexible printed circuit (FPC), a tape automated
bonding (TAB) tape, or a tape carrier package (TCP) is attached to
a light-emitting device; modules provided with a printed wiring
board at the end of a TAB tape or a TCP; and modules where an
integrated circuit (IC) is directly mounted on a light-emitting
element by a chip-on-glass (COG) method.
[0021] Since the carbazole derivative of the present invention
exhibits a high hole-transporting property, it can be mainly used
for a hole-transporting layer which is included in an EL layer of a
light-emitting element. In addition, the carbazole derivative of
the present invention is used for the hole-transporting layer to
form a light-emitting element, whereby a light-emitting element
having high luminous efficiency can be formed.
[0022] Further, a light-emitting device and an electronic device
which consumes low power and is driven at low voltage can be
obtained by using this light-emitting element.
BRIEF DESCRIPTION OF DRAWINGS
[0023] In the accompanying drawings:
[0024] FIGS. 1A and 1B are cross-sectional views each showing a
stacked-layer structure of a light-emitting element in Embodiment
Mode 2;
[0025] FIGS. 2A to 2C are cross-sectional views each showing a mode
of light emission of a light-emitting element in Embodiment Mode
2;
[0026] FIG. 3 is a cross-sectional view showing a stacked-layer
structure of a light-emitting element in Embodiment Mode 3;
[0027] FIGS. 4A and 4B are respectively a top view and a
cross-sectional view of an active matrix light-emitting device in
Embodiment Mode 4;
[0028] FIGS. 5A and 5B are respectively a perspective view and a
cross-sectional view of a passive matrix light-emitting device in
Embodiment Mode 4;
[0029] FIGS. 6A to 6D are views each showing an electronic device
in Embodiment Mode 5;
[0030] FIG. 7 is a view showing a liquid crystal display device
using a light-emitting device of the present invention as a
backlight;
[0031] FIG. 8 is a view showing a table lamp using a light-emitting
device of the present invention;
[0032] FIG. 9 is a view showing an indoor lighting device using a
light-emitting device of the present invention;
[0033] FIGS. 10A and 10B are graphs showing .sup.1H NMR charts of
PCBA1BP (abbreviation);
[0034] FIGS. 11A and 11B are graphs showing an absorption spectrum
and an emission spectrum of PCBA1BP (abbreviation);
[0035] FIGS. 12A and 12B are graphs showing .sup.1H NMR charts of
PCBBi1BP (abbreviation);
[0036] FIGS. 13A and 13B are graphs showing an absorption spectrum
and an emission spectrum of PCBBi1BP (abbreviation);
[0037] FIGS. 14A and 14B are graphs showing .sup.1H NMR charts of
PCBAF (abbreviation);
[0038] FIGS. 15A and 15B are graphs showing an absorption spectrum
and an emission spectrum of PCBAF (abbreviation);
[0039] FIGS. 16A and 16B are graphs showing .sup.1H NMR charts of
PCBASF (abbreviation);
[0040] FIGS. 17A and 17B are graphs showing an absorption spectrum
and an emission spectrum of PCBASF (abbreviation);
[0041] FIG. 18 is a cross-sectional view showing an element
structure of a light-emitting element in Embodiment 5;
[0042] FIG. 19 is a graph showing the current density vs. luminance
characteristics of a light-emitting element 1 and a light-emitting
element 2;
[0043] FIG. 20 is a graph showing the voltage vs. luminance
characteristics of the light-emitting element 1 and the
light-emitting element 2;
[0044] FIG. 21 is a graph showing the luminance vs. current
efficiency characteristics of the light-emitting element 1 and the
light-emitting element 2;
[0045] FIG. 22 is a graph showing the voltage vs. current
characteristics of the light-emitting element 1 and the
light-emitting element 2;
[0046] FIG. 23 is a graph showing emission spectra of the
light-emitting element 1 and the light-emitting element 2;
[0047] FIG. 24 is a graph showing the result of a continuous
lighting test of the light-emitting element 1 and the
light-emitting element 2 by constant current driving;
[0048] FIG. 25 is a graph showing the current density vs. luminance
characteristics of the light-emitting element 1 and a
light-emitting element 3;
[0049] FIG. 26 is a graph showing the voltage vs. luminance
characteristics of the light-emitting element 1 and the
light-emitting element 3;
[0050] FIG. 27 is a graph showing the luminance vs. current
efficiency characteristics of the light-emitting element 1 and the
light-emitting element 3;
[0051] FIG. 28 is a graph showing the voltage vs. current
characteristics of the light-emitting element 1 and the
light-emitting element 3;
[0052] FIG. 29 is a graph showing emission spectra of the
light-emitting element 1 and the light-emitting element 3;
[0053] FIG. 30 is a graph showing the current density vs. luminance
characteristics of the light-emitting element 1 and a
light-emitting element 4;
[0054] FIG. 31 is a graph showing the voltage vs. luminance
characteristics of the light-emitting element 1 and the
light-emitting element 4;
[0055] FIG. 32 is a graph showing the luminance vs. current
efficiency characteristics of the light-emitting element 1 and the
light-emitting element 4;
[0056] FIG. 33 is a graph showing the voltage vs. current
characteristics of the light-emitting element 1 and the
light-emitting element 4;
[0057] FIG. 34 is a graph showing emission spectra of the
light-emitting element 1 and the light-emitting element 4;
[0058] FIG. 35 is a graph showing the result of a continuous
lighting test of the light-emitting element 1 and the
light-emitting element 4 by constant current driving;
[0059] FIG. 36 is a graph showing the current density vs. luminance
characteristics of the light-emitting element 1 and a
light-emitting element 5;
[0060] FIG. 37 is a graph showing the voltage vs. luminance
characteristics of the light-emitting element 1 and the
light-emitting element 5;
[0061] FIG. 38 is a graph showing the luminance vs. current
efficiency characteristics of the light-emitting element 1 and the
light-emitting element 5;
[0062] FIG. 39 is a graph showing the voltage vs. current
characteristics of the light-emitting element 1 and the
light-emitting element 5;
[0063] FIG. 40 is a graph showing emission spectra of the
light-emitting element 1 and the light-emitting element 5;
[0064] FIG. 41 is a graph showing CV characteristics of PCBA1BP
(abbreviation);
[0065] FIG. 42 is a graph showing CV characteristics of PCBBi1BP
(abbreviation);
[0066] FIG. 43 is a graph showing CV characteristics of PCBAF
(abbreviation);
[0067] FIG. 44 is a graph showing CV characteristics of PCBASF
(abbreviation);
[0068] FIGS. 45A and 45B are graphs showing .sup.1H NMR charts of
PCTA1BP (abbreviation);
[0069] FIGS. 46A and 46B are graphs showing .sup.1H NMR charts of
PCTBi1BP (abbreviation);
[0070] FIGS. 47A and 47B are graphs showing .sup.1H NMR charts of
PCBANB (abbreviation);
[0071] FIGS. 48A and 48B are graphs showing .sup.1H NMR charts of
PCBNBB (abbreviation);
[0072] FIGS. 49A and 49B are graphs showing .sup.1H NMR charts of
PCBBiNB (abbreviation);
[0073] FIGS. 50A and 50B are graphs showing .sup.1H NMR charts of
PCBANT (abbreviation);
[0074] FIGS. 51A and 51B are graphs showing .sup.1H NMR charts of
BCBA1BP (abbreviation);
[0075] FIGS. 52A and 52B are graphs showing .sup.1H NMR charts of
BCBANB (abbreviation);
[0076] FIGS. 53A and 53B are graphs showing .sup.1H NMR charts of
BCBBiNB (abbreviation);
[0077] FIGS. 54A and 54B are graphs showing .sup.1H NMR charts of
NBCBA1BP (abbreviation);
[0078] FIGS. 55A and 55B are graphs showing .sup.1H NMR charts of
NCBA1BP (abbreviation);
[0079] FIG. 56 is a graph showing the voltage vs. luminance
characteristics of the light-emitting element 1 and light-emitting
elements 6 to 8;
[0080] FIG. 57 is a graph showing the luminance vs. current
efficiency characteristics of the light-emitting element 1 and the
light-emitting elements 6 to 8;
[0081] FIG. 58 is a graph showing the voltage vs. current
characteristics of the light-emitting element 1 and the
light-emitting elements 6 to 8;
[0082] FIG. 59 is a graph showing emission spectra of the
light-emitting element 1 and the light-emitting elements 6 to
8;
[0083] FIG. 60 is a graph showing the result of a continuous
lighting test of the light-emitting element 1 and the
light-emitting elements 6 to 8 by constant current driving;
[0084] FIGS. 61A and 61B are graphs showing .sup.1H NMR charts of
PCBBi1BPIII (abbreviation);
[0085] FIGS. 62A to 62C are graphs showing .sup.1H NMR charts of
PCBA1BPIV (abbreviation);
[0086] FIGS. 63A and 63B are graphs showing .sup.1H NMR charts of
PCBNBB.beta. (abbreviation); and
[0087] FIGS. 64A and 64B are graphs showing .sup.1H NMR charts of
PCBBiFLP (abbreviation).
BEST MODE FOR CARRYING OUT THE INVENTION
[0088] The embodiment modes and embodiments according to the
present invention will hereinafter be described in detail with
reference to the drawings. However, the present invention is not
limited to description to be given below, and it is to be easily
understood that modes and details thereof can be variously modified
without departing from the purpose and the scope of the present
invention. Thus, the present invention is not interpreted while
limiting to the following description of the embodiment modes and
embodiments.
Embodiment Mode 1
[0089] In Embodiment Mode 1, a carbazole derivative of the present
invention will be described.
[0090] The carbazole derivative of the present invention is
represented by a general formula (1).
##STR00008##
[0091] In the formula, .alpha..sup.1, .alpha..sup.2, .alpha..sup.3,
and .alpha..sup.4 each represent an arylene group having less than
or equal to 13 carbon atoms, which forms a ring; Ar.sup.1 and
Ar.sup.2 each represent an aryl group having less than or equal to
13 carbon atoms, which forms a ring; R.sup.1 represents any of a
hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a
substituted or unsubstituted phenyl group, and a substituted or
unsubstituted biphenyl group; and R.sup.2 represents any of alkyl
group having 1 to 6 carbon atoms, a substituted or unsubstituted
phenyl group, and a substituted or unsubstituted biphenyl group. In
addition, l, m, and n are each independent, which is 0 or 1.
[0092] In the general formula (1), .alpha..sup.1 to .alpha..sup.4
each represent an arylene group having less than or equal to 13
carbon atoms, which forms a ring. Specifically, substituents
represented by structural formulas (2-1) to (2-12) can be
given.
##STR00009## ##STR00010##
[0093] In the formula, R.sup.11 to R.sup.16, R.sup.21 to R.sup.30,
R.sup.31 to R.sup.38, and R.sup.41 to R.sup.45 each represent any
of a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a
phenyl group, and a biphenyl group. R.sup.46 and R.sup.47 each
represent any of an alkyl group having 1 to 6 carbon atoms and a
phenyl group. In addition, R.sup.46 and R.sup.47 may be connected
to each other to form a ring. R.sup.48 represents any of a hydrogen
atom, an alkyl group having 1 to 6 carbon atoms, a phenyl group,
and a biphenyl group.
[0094] In the general formula (1), Ar.sup.1 and Ar.sup.2 each
represent an aryl group having less than or equal to 13 carbon
atoms, which forms a ring. Specifically, substituents represented
by structural formulas (3-1) to (3-6) can be given.
##STR00011##
[0095] In the formula, R.sup.51 to R.sup.56, R.sup.61 to R.sup.70,
R.sup.71 to R.sup.78, and R.sup.81 to R.sup.85 each represent any
of a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a
phenyl group, and a biphenyl group. R.sup.86 and R.sup.87 each
represent any of an alkyl group having 1 to 6 carbon atoms and a
phenyl group. In addition, R.sup.86 and R.sup.87 may be connected
to each other to form a ring. R.sup.88 and R.sup.89 each represent
any of a hydrogen atom, an alkyl group having 1 to 6 carbon atoms,
a phenyl group, and a biphenyl group.
[0096] In the general formula (1), R.sup.1 represents any of a
hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a
substituted or unsubstituted phenyl group, and a substituted or
unsubstituted biphenyl group; and R.sup.2 represents any of an
alkyl group having 1 to 6 carbon atoms, a substituted or
unsubstituted phenyl group, and a substituted or unsubstituted
biphenyl group. Specifically, substituents represented by
structural formulas (4-1) to (4-9) can be given for R.sup.1, and
the substituents represented by the structural formulas (4-2) to
(4-9) can be given for R.sup.2.
##STR00012##
[0097] In the formula, R.sup.51 to R.sup.70 each represent any of a
hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a phenyl
group, and a biphenyl group.
[0098] As a specific example of the carbazole derivatives of the
present invention represented by the general formula (1), carbazole
derivatives represented by structural formulas (9) to (425) can be
given. However, the present invention is not limited thereto.
##STR00013## ##STR00014## ##STR00015## ##STR00016## ##STR00017##
##STR00018## ##STR00019## ##STR00020## ##STR00021## ##STR00022##
##STR00023## ##STR00024## ##STR00025## ##STR00026## ##STR00027##
##STR00028## ##STR00029## ##STR00030## ##STR00031## ##STR00032##
##STR00033## ##STR00034## ##STR00035## ##STR00036## ##STR00037##
##STR00038## ##STR00039## ##STR00040## ##STR00041## ##STR00042##
##STR00043## ##STR00044## ##STR00045## ##STR00046## ##STR00047##
##STR00048## ##STR00049## ##STR00050## ##STR00051## ##STR00052##
##STR00053## ##STR00054## ##STR00055## ##STR00056## ##STR00057##
##STR00058## ##STR00059## ##STR00060## ##STR00061## ##STR00062##
##STR00063## ##STR00064## ##STR00065## ##STR00066## ##STR00067##
##STR00068## ##STR00069## ##STR00070## ##STR00071## ##STR00072##
##STR00073## ##STR00074## ##STR00075## ##STR00076## ##STR00077##
##STR00078## ##STR00079## ##STR00080## ##STR00081## ##STR00082##
##STR00083## ##STR00084## ##STR00085## ##STR00086## ##STR00087##
##STR00088## ##STR00089## ##STR00090## ##STR00091## ##STR00092##
##STR00093## ##STR00094## ##STR00095## ##STR00096## ##STR00097##
##STR00098## ##STR00099## ##STR00100## ##STR00101## ##STR00102##
##STR00103##
[0099] In addition, the carbazole derivative of the present
invention represented by the general formula (1) can be synthesized
by a synthetic method represented by the following synthetic
schemes (A-1) to (A-7), a synthetic scheme (B-1), and synthetic
schemes (C-1) to (C-2).
[Synthetic Method of Halogenated Secondary Arylamine (Compound
A)]
[0100] Halogenated secondary arylamine represented by a general
formula (compound A) can be synthesized in a manner like the
following synthetic scheme (A-1). In other words, first, secondary
arylamine (compound A.sub.1) is halogenated by using a halogenating
agent, whereby the halogenated secondary arylamine (compound A) can
be obtained. Note that as the halogenating agent,
N-bromosuccinimide (NBS), N-iodosuccinimide (NIS), bromine, iodine,
potassium iodide, or the like can be used. In addition, each
X.sup.1 represents a halogen group, which is preferably a bromo
group or an iodine group.
##STR00104##
[Synthetic Method of a Halogenated Carbazole Derivative (Compound
B.sub.2)]
[0101] A halogenated carbazole derivative represented by a general
formula (compound B.sub.2) can be synthesized in a manner like the
following synthetic scheme (A-2). In other words, first, a
carbazole derivative (compound B.sub.1) is halogenated by using a
halogenating agent, whereby the halogenated carbazole derivative
(compound B.sub.2) can be obtained. Note that as the halogenating
agent, N-bromosuccinimide (NBS), N-iodosuccinimide (NIS), bromine,
iodine, potassium iodide, or the like can be used. In addition,
each X.sup.1 represents a halogen group, which is preferably a
bromo group or an iodine group.
##STR00105##
[Synthetic Method of a Compound (Compound B) in which
9H-carbazol-3-boronic Acid or the Third Position of 9H-carbazol is
Substituted by Organoboron]
[0102] A compound in which the third position of 9H-carbazole is
substituted by boronic acid or organoboron, which is represented by
a general formula (compound B), can be synthesized in a manner like
the following synthetic scheme (A-3). In other words, boron
oxidation or organoboronation is performed on the halogenated
carbazole derivative (compound B.sub.2) using an alkyllithium
reagent and a boron reagent, whereby the compound in which the
third position of 9H-carbazole is substituted by boronic acid or
organoboron (compound B) can be obtained.
[0103] Note that R.sup.99 in the scheme (A-3) represents an alkyl
group having 1 to 6 carbon atoms. R.sup.98 presents an alkyl group
having 1 to 6 carbon atoms. In addition, R.sup.100 and R.sup.10l
each represent a hydrogen atom or an alkyl group having 1 to 6
carbon atoms. R.sup.102 and R.sup.103 may be connected to each
other to form a ring. In addition, n-butyllithium, methyllithium,
or the like can be used as the alkyllithium reagent. Trimethyl
borate, isopropyl borate, or the like can be used as the boron
reagent.
##STR00106##
[Synthetic Method of Secondary Arylamine (Compound C.sub.3)]
[0104] Secondary arylamine represented by a general formula
(compound C.sub.3) can be synthesized in a manner like the
following synthetic scheme (A-4). In other words, halogenated aryl
(compound Cl) and primary arylamine (compound C.sub.2) are coupled
in the presence of a base using a metal catalyst, whereby the
secondary arylamine (compound C.sub.3) can be obtained.
##STR00107##
[0105] In the case where a Buchwald-Hartwig reaction is performed,
as the palladium catalyst which can be used in the synthetic scheme
(A-4), although bis(dibenzylideneacetone)palladium(0),
palladium(II) acetate, and the like can be given, the palladium
catalyst which can be used is not limited thereto. As a ligand in
the palladium catalyst which can be used in the synthetic scheme
(A-4), although tri(tert-butyl)phosphine, tri(n-hexyl)phosphine,
tricyclohexylphosphine, and the like can be given, the ligand which
can be used is not limited thereto.
[0106] As a base which can be used in the synthetic scheme (A-4),
although an organic base such as sodium tert-butoxide, an inorganic
base such as potassium carbonate, and the like can be given, the
base which can be used is not limited thereto. In addition, as a
solvent that can be used in the synthetic scheme (A-4), although
toluene, xylene, benzene, tetrahydrofuran, and the like can be
given, the solvent which can be used is not limited thereto.
[0107] The case in which an Ullmann reaction is performed in the
synthetic scheme (A-4) is described. In the synthetic scheme (A-4),
R.sup.104 and R.sup.105 each represent a halogen group, an acetyl
group, or the like, and chlorine, bromine, and iodine can be given
as the halogen group. It is preferable that R.sup.104 be iodine to
form copper(I) iodide or that R.sup.105 be an acetyl group to form
a copper(II) acetate. The copper compound used for the reaction is
not limited thereto, and copper can be used as an alternative to
the copper compound. As a base which can be used in the synthetic
scheme (A-4), although an inorganic base such as potassium
carbonate can be given, the base which can be used is not limited
thereto.
[0108] As a solvent which can be used in the synthetic scheme
(A-4), although 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)pyrimidinone
(abbreviation: DMPU), toluene, xylene, benzene, and the like can be
given, the solvent which can be used is not limited thereto. DMPU
or xylene which has a high boiling point is preferably used
because, by an Ullmann reaction, an object can be obtained in a
shorter time and at a higher yield when the reaction temperature is
greater than or equal to 100.degree. C. Since it is further
preferable that the reaction temperature be a temperature greater
than or equal to 150.degree. C., DMPU is more preferably used.
[Synthetic Method of Tertiary Arylamine (Compound C.sub.5)]
[0109] Tertiary arylamine represented by a general formula
(compound C.sub.5) can be synthesized in a manner like the
following synthetic scheme (A-5). In other words, the secondary
arylamine (compound C.sub.3) and halogenated aryl (compound
C.sub.4) are coupled in the presence of a base using a metal
catalyst, whereby the tertiary arylamine (compound C.sub.5) can be
obtained.
##STR00108##
[0110] In the case where a Buchwald-Hartwig reaction is performed,
as the palladium catalyst which can be used in the synthetic scheme
(A-5), although bis(dibenzylideneacetone)palladium(0),
palladium(II) acetate, and the like can be given, the palladium
catalyst which can be used is not limited thereto. As a ligand in
the palladium catalyst which can be used in the synthetic scheme
(A-5), although tri(tert-butyl)phosphine, tri(n-hexyl)phosphine,
tricyclohexylphosphine, and the like can be given, the ligand which
can be used is not limited thereto.
[0111] As a base which can be used in the synthetic scheme (A-5),
although an organic base such as sodium tert-butoxide, an inorganic
base such as potassium carbonate, and the like can be given, the
base which can be used is not limited thereto. In addition, as a
solvent that can be used in the synthetic scheme (A-5), although
toluene, xylene, benzene, tetrahydrofuran, and the like can be
given, the solvent which can be used is not limited thereto.
[0112] The case in which an Ullmann reaction is performed in the
synthetic scheme (A-5) is described. In the synthetic scheme (A-5),
R.sup.104 and R.sup.105 each represent a halogen group, an acetyl
group, or the like, and chlorine, bromine, and iodine can be given
as the halogen group. It is preferable that R.sup.104 be iodine to
form copper(I) iodide or that R.sup.105 be an acetyl group to form
a copper(II) acetate. The copper compound used for the reaction is
not limited thereto, and copper can be used as an alternative to
the copper compound. As a base which can be used in the synthetic
scheme (A-5), although an inorganic base such as potassium
carbonate can be given, the base which can be used is not limited
thereto.
[0113] As a solvent which can be used in the synthetic scheme
(A-5), although 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)pyrimidinone
(abbreviation: DMPU), toluene, xylene, benzene, and the like can be
given, the solvent which can be used is not limited thereto. DMPU
or xylene which has a high boiling point is preferably used
because, by an Ullmann reaction, an object can be obtained in a
shorter time and at a higher yield when the reaction temperature is
greater than or equal to 100.degree. C. Since it is further
preferable that the reaction temperature be a temperature greater
than or equal to 150.degree. C., DMPU is more preferably used.
[Synthetic Method of Tertiary Arylamine (Compound C.sub.5)]
[0114] Tertiary arylamine represented by a general formula
(compound C.sub.5) can be synthesized in a manner like the
following synthetic scheme (A-6). In other words, the primary
arylamine (compound C.sub.2) and the halogenated aryl (compounds
C.sub.1 and C.sub.4) are coupled in the presence of a base using a
metal catalyst, whereby the tertiary arylamine (compound C.sub.5)
can be obtained. However, when Ar.sup.1 and Ar.sup.2 are the same,
.beta..sup.1 and .beta..sup.2 are the same, and l and m are the
same, the compound C.sub.5 can be obtained with high yield.
##STR00109##
[0115] In the case where a Buchwald-Hartwig reaction is performed,
as the palladium catalyst which can be used in the synthetic scheme
(A-6), although bis(dibenzylideneacetone)palladium(0),
palladium(II) acetate, and the like can be given, the palladium
catalyst which can be used is not limited thereto. As a ligand in
the palladium catalyst which can be used in the synthetic scheme
(A-6), although tri(tert-butyl)phosphine, tri(n-hexyl)phosphine,
tricyclohexylphosphine, and the like can be given, the ligand which
can be used is not limited thereto.
[0116] As a base which can be used in the synthetic scheme (A-6),
although an organic base such as sodium tert-butoxide, an inorganic
base such as potassium carbonate, and the like can be given, the
base which can be used is not limited thereto. In addition, as a
solvent that can be used in the synthetic scheme (A-6), although
toluene, xylene, benzene, tetrahydrofuran, and the like can be
given, the solvent which can be used is not limited thereto.
[0117] The case in which an Ullmann reaction is performed in the
synthetic scheme (A-6) is described. In the synthetic scheme (A-6),
R.sup.104 and R.sup.105 each represent a halogen group, an acetyl
group, or the like, and chlorine, bromine, and iodine can be given
as the halogen group. It is preferable that R.sup.104 be iodine to
form copper(I) iodide or that R.sup.105 be an acetyl group to form
a copper(II) acetate. The copper compound used for the reaction is
not limited thereto, and copper can be used as an alternative to
the copper compound. As a base which can be used in the synthetic
scheme (A-6), although an inorganic base such as potassium
carbonate can be given, the base which can be used is not limited
thereto.
[0118] As a solvent which can be used in the synthetic scheme
(A-6), although 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)pyrimidinone
(abbreviation: DMPU), toluene, xylene, benzene, and the like can be
given, the solvent which can be used is not limited thereto. DMPU
or xylene which has a high boiling point is preferably used
because, by an Ullmann reaction, an object can be obtained in a
shorter time and at a higher yield when the reaction temperature is
greater than or equal to 100.degree. C. Since it is further
preferable that the reaction temperature be a temperature greater
than or equal to 150.degree. C., DMPU is more preferably used.
[Synthetic Method of Halogenated Tertiary Arylamine Derivative
(Compound C)]
[0119] Halogenated tertiary arylamine represented by a general
formula (compound C) can be synthesized in a manner like the
following synthetic scheme (A-7). In other words, first, tertiary
arylamine (compound C.sub.5) is halogenated by using a halogenating
agent, whereby the halogenated tertiary arylamine (compound C) can
be obtained. Note that as the halogenating agent,
N-bromosuccinimide (NBS), N-iodosuccinimide (NIS), bromine, iodine,
potassium iodide, or the like can be used. In addition, each
X.sup.1 represents a halogen group, which is preferably a bromo
group or an iodine group.
##STR00110##
[Synthetic Method of Secondary Arylamine (Compound D)]
[0120] Secondary arylamine having carbazole, which is represented
by a general formula (compound D), can be synthesized in a manner
like the following synthetic scheme (B-1). In other words, the
halogenated secondary arylamine (compound A) and the compound in
which the third position of 9H-carbazole is substituted by boronic
acid or organoboron (compound B) can be coupled in the presence of
a base using a metal catalyst. Accordingly, the secondary arylamine
having carbazole (compound D) can be obtained.
##STR00111##
[0121] In any of the above schemes, the case of using a
Suzuki-Miyaura reaction is described. As a palladium catalyst which
can be used as a metal catalyst, palladium(II) acetate,
tetrakis(triphenylphosphine)palladium(0),
bis(triphenylphosphine)palladium(II) dichloride, and the like can
be given. As a ligand in the above palladium catalyst,
tri(ortho-tolyl)phosphine, triphenylphosphine,
tricyclohexylphosphine, and the like can be given. In addition, as
the above base, an organic base such as sodium tert-butoxide, an
inorganic base such as potassium carbonate, and the like can be
given. As the solvent which can be used, a mixed solvent of toluene
and water; a mixed solvent of toluene, an alcohol such as ethanol,
and water; a mixed solvent of xylene and water; a mixed solvent of
xylene, an alcohol such as ethanol, and water; a mixed solvent of
benzene and water; a mixed solvent of benzene, an alcohol such as
ethanol, and water; a mixed solvent of ethers such as
ethyleneglycoldimethylether and water; and the like can be
given.
[0122] However, the catalyst, ligand, base, and solvent which can
be used are not limited thereto.
[0123] In addition, in any of the above schemes, cross coupling
using organoaluminum, organozirconium, organozinc, or organotin
compound, or the like, in addition to arylboronic acid, may be
employed as a base material. However, the present invention is not
limited thereto.
[Synthetic Method of Tertiary Arylamine Having Carbazole (Compound
E)]
[0124] Tertiary arylamine having carbazole represented by a general
formula (compound E) can be synthesized in a manner like the
following synthetic scheme (C-1). In other words, the secondary
arylamine having carbazole (compound D) and the halogenated aryl
(compound C.sub.4) are coupled in the presence of a base using a
metal catalyst, whereby the tertiary arylamine having carbazole
(compound E), which is a final product, can be obtained.
##STR00112##
[0125] In any of the above schemes, the case of using a
Suzuki-Miyaura reaction is described. As a palladium catalyst which
can be used as a metal catalyst, palladium(II) acetate,
tetrakis(triphenylphosphine)palladium(0),
bis(triphenylphosphine)palladium(II) dichloride, and the like can
be given. As a ligand in the above palladium catalyst,
tri(ortho-tolyl)phosphine, triphenylphosphine,
tricyclohexylphosphine, and the like can be given. In addition, as
the above base, an organic base such as sodium tert-butoxide, an
inorganic base such as potassium carbonate, and the like can be
given. As the solvent which can be used, a mixed solvent of toluene
and water; a mixed solvent of toluene, an alcohol such as ethanol,
and water; a mixed solvent of xylene and water; a mixed solvent of
xylene, an alcohol such as ethanol, and water; a mixed solvent of
benzene and water; a mixed solvent of benzene, an alcohol such as
ethanol, and water; a mixed solvent of ethers such as
ethyleneglycoldimethylether and water; and the like can be
given.
[0126] However, the catalyst, ligand, base, and solvent which can
be used are not limited thereto.
[0127] In addition, in any of the above schemes, cross coupling
using organoaluminum, organic zirconium, organozinc,
organozirconium, organotin, or the like, in addition to arylboronic
acid, may be employed as a base material. However, the present
invention is not limited thereto.
[Another Synthetic Method of the Tertiary Arylamine Having
Carbazole (Compound E)]
[0128] The tertiary arylamine having carbazole represented by the
general formula (compound E) can be synthesized in a manner like
the following synthetic scheme (C-2). In other words, first, the
halogenated tertiary arylamine (compound C) and the compound in
which the third position of 9H-carbazole is substituted by boronic
acid or organoboron (compound B) are coupled in the presence of a
base using a metal catalyst, whereby the tertiary arylamine having
carbazole (compound E), which is a final product, can be
obtained.
##STR00113##
Embodiment Mode 2
[0129] In Embodiment Mode 2, a light-emitting element which is
formed using, for a hole-transporting layer, the carbazole
derivative of the present invention described in Embodiment Mode 1
will be described.
[0130] The light-emitting element in Embodiment Mode 2 includes a
first electrode which functions as an anode, a second electrode
which functions as a cathode, and an EL layer interposed between
the first electrode and the second electrode. Note that the
light-emitting element in Embodiment Mode 2 can obtain light
emission when voltage is applied to each electrode so that the
potential of the first electrode is higher than that of the second
electrode.
[0131] In addition, the EL layer of the light-emitting element in
Embodiment Mode 2 includes in its structure a first layer (a
hole-injecting layer), a second layer (a hole-transporting layer),
a third layer (a light-emitting layer), a fourth layer (an
electron-transporting layer), and a fifth layer (an
electron-injecting layer), from the first electrode side.
[0132] A structure of the light-emitting element in Embodiment Mode
2 is described with reference to FIGS. 1A and 1B. A substrate 101
is used as a support of the light-emitting element. For the
substrate 101, glass, quartz, plastics, or the like can be used,
for example.
[0133] Note that although the above substrate 101 may remain in a
light-emitting device or an electronic device which is a product
utilizing the light-emitting element of the present invention, the
substrate 101 may only have a function as the support of the
light-emitting element in the manufacturing process of the
light-emitting element, without remaining in an end product.
[0134] For a first electrode 102 formed over the substrate 101, a
metal, an alloy, an electrically conductive compound, a mixture
thereof, or the like having a high work function (specifically, a
work function of 4.0 eV or more) is preferably used. Specifically,
the following examples can be given: indium tin oxide (ITO), indium
tin oxide containing silicon or silicon oxide, indium zinc oxide
(IZO), and indium oxide containing tungsten oxide and zinc oxide.
Besides, gold (Au), platinum (Pt), nickel (Ni), tungsten (W),
chromium (Cr), molybdenum (Mo), iron (Fe), cobalt (Co), copper
(Cu), palladium (Pd), titanium (Ti), nitrides of the metal
materials (e.g. titanium nitride), and the like can be given.
However, in the present invention, a first layer 111 in an EL layer
103 which is formed in contact with the first electrode 102 is
formed using a composite material with which holes are easily
injected regardless of the work function of the first electrode
102. Therefore, a variety of known methods can be used as long as
it is a material that can serve as an electrode material (e.g., a
metal, an alloy, an electrically conductive compound, a mixture
thereof, or the like, or an element belonging to Group 1 or 2 of
the periodic table is also included).
[0135] A film of any of those materials is generally formed by a
sputtering method. For example, indium zinc oxide (IZO) can be
formed by a sputtering method using a target in which 1 wt % to 20
wt % zinc oxide is added to indium oxide; and indium oxide
containing tungsten oxide and zinc oxide can be formed by a
sputtering method using a target in which 0.5 wt % to 5 wt %
tungsten oxide and 0.1 wt % to 1 wt % zinc oxide are added to
indium oxide. Alternatively, the first layer 111 may be formed by a
vacuum evaporation method, an ink-jet method, a spin-coating
method, or the like.
[0136] Further, when a layer containing a composite material which
will be described later is used as a material used for the first
layer 111 formed in contact with the first electrode 102 in the EL
layer 103 formed over the first electrode 102, any of a variety of
materials such as metals, alloys, and electrically conductive
compounds; a mixture thereof; or the like can be used as a
substance used for the first electrode 102 regardless of their work
functions. For example, aluminum (Al), silver (Ag), an alloy
containing aluminum (AlSi), or the like can also be used.
[0137] Furthermore, an element belonging to Group 1 or 2 of the
periodic table, which is a low work function material, that is, an
alkali metal such as lithium (Li) or cesium (Cs), an alkaline earth
metal such as magnesium (Mg), calcium (Ca), or strontium (Sr), an
alloy containing any of these metals (such as an MgAg alloy or an
AlLi alloy), a rare-earth metal such as europium (Eu) or ytterbium
(Yb), an alloy containing such rare-earth metals, or the like can
also be used.
[0138] Note that in the case where the first electrode 102 is
formed using an alkali metal, an alkaline-earth metal, or an alloy
thereof, a vacuum evaporation method or a sputtering method can be
employed. Note that in the case of using a silver paste or the
like, a coating method, an ink-jet method, or the like can be
used.
[0139] For the EL layer 103 formed over the first electrode 102, a
known substance can be used, and any of a low molecular compound
and a macromolecular compound can be used. Note that the substance
used to form the EL layer 103 has not only a structure formed of
only an organic compound but also a structure partially containing
an inorganic compound.
[0140] For forming the EL layer 103, a hole-injecting layer
containing a substance having a high hole-injecting property, a
hole-transporting layer containing a substance having a high
hole-transporting property, a light-emitting layer containing a
light-emitting substance, an electron-transporting layer containing
a substance having a high electron-transporting property, an
electron-injecting layer containing a substance having a high
electron-injecting property, and the like are combined with each
other and stacked, as appropriate.
[0141] Note that in the EL layer 103 shown in FIG. 1A, the first
layer (a hole-injecting layer) 111, a second layer (a
hole-transporting layer) 112, a third layer (a light-emitting
layer) 113, a fourth layer (an electron-transporting layer) 114,
and a fifth layer (an electron-injecting layer) 115 are
sequentially stacked from the first electrode 102 side.
[0142] The first layer 111 which is a hole-injecting layer is a
hole-injecting layer containing a substance having a high
hole-injecting property. As the substance having a high
hole-injecting property, molybdenum oxide, titanium oxide, vanadium
oxide, rhenium oxide, ruthenium oxide, chromium oxide, zirconium
oxide, hafnium oxide, tantalum oxide, silver oxide, tungsten oxide,
manganese oxide, or the like can be used. Alternatively, as a
low-molecular organic compound, a phthalocyanine-based compound
such as phthalocyanine (abbreviation: H.sub.2Pc), copper(II)
phthalocyanine (abbreviation: CuPc), or vanadyl phthalocyanine
(abbreviation: VOPc) can be given.
[0143] In addition, the following aromatic amine compounds which
are low-molecular organic compounds can also be given:
4,4',4''-tris(N,N-diphenylamino)triphenylamine (abbreviation:
TDATA);
4,4',4''-tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine
(abbreviation: MTDATA);
4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl
(abbreviation: DPAB);
4,4'-bis(N-{4-[N'-(3-methylphenyl)-N'-phenylamino]phenyl}-N-phenyl-
amino)biphenyl (abbreviation: DNTPD);
1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene
(abbreviation: DPA3B);
3-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole
(abbreviation: PCzPCA1);
3,6-bis[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole
(abbreviation: PCzPCA2);
3-[N-(1-naphtyl)-N-(9-phenylcarbazol-3-yl)amino]-9-phenylcarbazole
(abbreviation: PCzPCN1); and the like. Note that the carbazole
derivative of the present invention which is described in
Embodiment Mode 1 can also be used in a similar manner.
[0144] Further, a macromolecular compound (an oligomer, a
dendrimer, a polymer, or the like) can also be used. For example,
macromolecular compounds such as poly(N-vinylcarbazole)
(abbreviation: PVK); poly(4-vinyltriphenylamine) (abbreviation:
PVTPA), poly[N-(4-{N
[4-(4-diphenylamino)phenyl]phenyl-N'-phenylamino}phenyl)methacrylamide]
(abbreviation: PTPDMA), and
poly[N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine]
(abbreviation: Poly-TPD) can be given. In addition, a
macromolecular compound, to which acid is added, such as
poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonic acid)
(PEDOT/PSS) or polyaniline/poly(styrenesulfonic acid)
(abbreviation: PAni/PSS) can also be used.
[0145] Alternatively, for the first layer 111, the composite
material in which a substance having an acceptor property is
contained in a substance having a high hole-transporting property
can be used. Note that by using the substance having a high
hole-transporting property containing a substance having an
acceptor property, a material used to form an electrode may be
selected regardless of its work function. In other words, not only
a material with a high work function but also a material with a low
work function can be used as the first electrode 102. Such
composite materials can be formed by co-evaporation of a substance
having a high hole-transporting property and a substance having an
acceptor property. Note that in this specification, "composition"
means not only a simple mixture of two materials but also a mixture
of a plurality of materials in a condition where an electric charge
is given and received among the materials.
[0146] As an organic compound used for the composite material,
various compounds such as an aromatic amine compound, a carbazole
derivative, aromatic hydrocarbon, and a macromolecular compound (an
oligomer, a dendrimer, a polymer, or the like) can be used. The
organic compound used for the composite material is preferably an
organic compound having a high hole-transporting property.
Specifically, a substance having a hole mobility of 10.sup.-6
cm.sup.2/Vs or more is preferably used. However, other than the
above substances may be used as long as the substance has a higher
hole-transporting property than an electron-transporting property.
The organic compound that can be used for the composite material is
specifically shown below.
[0147] As an organic compound used for the composite material, for
example, an aromatic amine compound such as MTDATA, TDATA, DPAB,
DNTPD, DPA3B, PCzPCA1, PCzPCA2, PCzPCN1,
4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB
or .alpha.-NPD), and
N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine
(abbreviation: TPD); and a carbazole derivative such as
4,4'-di(N-carbazolyl)biphenyl (abbreviation: CBP),
1,3,5-tris[4-(N-carbazolyl)phenyl]benzene (abbreviation: TCPB),
9-[4-(N-carbazolyl)]phenyl-10-phenylanthracene (abbreviation:
CzPA), and
1,4-bis[4-(N-carbazolyl)phenyl]-2,3,5,6-tetraphenylbenzene can be
given. Note that the carbazole derivative of the present invention
which is described in Embodiment Mode 1 can also be used in a
similar manner.
[0148] In addition, the following aromatic hydrocarbon compounds
can be given: 2-tert-butyl-9,10-di(2-naphthyl)anthracene
(abbreviation: t-BuDNA);
2-tert-butyl-9,10-di(1-naphthyl)anthracene;
9,10-bis(3,5-diphenylphenyl)anthracene (abbreviation: DPPA);
2-tert-butyl-9,10-bis(4-phenylphenyl)anthracene (abbreviation:
t-BuDBA); 9,10-di(2-naphthyl)anthracene (abbreviation: DNA);
9,10-diphenylanthracene (abbreviation: DPAnth);
2-tert-butylanthracene (abbreviation: t-BuAnth);
9,10-bis(4-methyl-1-naphthyl)anthracene (abbreviation: DMNA);
9,10-bis[2-(1-naphthyl)phenyl]-2-tert-butyl-anthracene;
9,10-bis[2-(1-naphthyl)phenyl]anthracene;
2,3,6,7-tetramethyl-9,10-di(1-naphthyl)anthracene; and the
like.
[0149] Further, the following aromatic hydrocarbon compound
compounds can also be given:
2,3,6,7-tetramethyl-9,10-di(2-naphthyl)anthracene; 9,9'-bianthryl;
10,10'-diphenyl-9,9'-bianthryl;
10,10'-bis(2-phenylphenyl)-9,9'-bianthryl;
10,10'-bis[(2,3,4,5,6-pentaphenyl)phenyl]-9,9'-bianthryl;
anthracene; tetracene; rubrene; perylene;
2,5,8,11-tetra(tert-butyl)perylene; pentacene; coronene;
4,4'-bis(2,2-diphenylvinyl)biphenyl (abbreviation: DPVBi);
9,10-bis[4-(2,2-diphenylvinyl)phenyl]anthracene (abbreviation:
DPVPA); and the like.
[0150] As a substance having an acceptor property, organic
compounds such as
7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation:
F.sub.4-TCNQ) and chloranil, and a transition metal oxide can be
given. In addition, oxides of metals belonging to Groups 4 to 8 of
the periodic table can be given. Specifically, vanadium oxide,
niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide,
tungsten oxide, manganese oxide, and rhenium oxide are preferable
because of a high electron-accepting property. Among these,
molybdenum oxide is especially preferable because it is stable in
the air and its hygroscopic property is low so that it can be
easily treated.
[0151] Note that a composite material, which is formed using the
above macromolecular compound such as PVK, PVTPA, PTPDMA, or
Poly-TPD and the above substance having an acceptor property, may
be used for the first layer 111. Note that a composite material,
which is formed combining the carbazole derivative of the present
invention which is described in Embodiment Mode 1 with the above
substance having an acceptor property, can also be used for the
first layer 111.
[0152] The second layer 112 which is a hole-transporting layer is a
hole-transporting layer containing a substance having a high
hole-transporting property. Note that the carbazole derivative of
the present invention which is described in Embodiment Mode 1 is
used for the second layer 112 in Embodiment Mode 2.
[0153] In addition, the carbazole derivative of the present
invention which is described in Embodiment Mode 1 can also be used
for both the first layer 111 and the second layer 112. In this
case, an element can be manufactured easily and material use
efficiency can also be improved. Moreover, since energy diagrams of
the first layer 111 and the second layer 112 are the same or
similar, carriers can be transported easily between the first layer
111 and the second layer 112.
[0154] The third layer 113 is a light-emitting layer containing a
substance having a high light-emitting property. For the third
layer 113, any of low molecular organic compounds given below can
be used.
[0155] As a light-emitting substance for blue emission,
N,N'-bis[4-(9H-carbazol-9-yl)phenyl]-N,N'-diphenylstilbene-4,4'-diamine
(abbreviation:
YGA2S),4-(9H-carbazol-9-yl)-4'-(10-phenyl-9-anthryl)triphenylamine
(abbreviation: YGAPA), and the like can be given.
[0156] As a light-emitting substance for green emission, the
following can be given:
N-(9,10-diphenyl-2-anthryl)-N,9-diphenyl-9H-carbazol-3-amine
(abbreviation: 2PCAPA);
N-[9,10-bis(1,1'-biphenyl-2-yl)-2-anthryl]-N,9-diphenyl-9H-carbazol-3-ami-
ne (abbreviation: 2PCABPhA);
N-(9,10-diphenyl-2-anthryl)-N,N',N'-triphenyl-1,4-phenylenediamine
(abbreviation: 2DPAPA);
N-[9,10-bis(1,1'-biphenyl-2-yl)-2-anthryl]-N,N'-triphenyl-1,4-phenylenedi-
amine (abbreviation: 2DPABPhA);
N-[9,10-bis(1,1'-biphenyl-2-yl)]-N-[4-(9H-carbazol-9-yl)phenyl]-N-phenyla-
nthracen-2-amine (abbreviation: 2YGABPhA);
N,N,9-triphenylanthracen-9-amine (abbreviation: DPhAPhA); and the
like.
[0157] As a light-emitting substance for yellow light emission,
rubrene, 5,12-bis(1,1'-biphenyl-4-yl)-6,11-diphenyltetracene
(abbreviation: BPT), and the like can be given. Further, as a
light-emitting substance for red light emission,
N,N,N',N'-tetrakis(4-methylphenyl)tetracene-5,11-diamine
(abbreviation: p-mPhTD),
7,13-diphenyl-N,N,N',N'-tetrakis(4-methylphenyl)acenaphtho[1,2-a]fluorant-
hene-3,10-diamine (abbreviation: p-mPhAFD), and the like can be
given.
[0158] Further, the third layer 113 may have a structure in which
the above substance having a high light-emitting property is
dispersed in another substance. Note that in the case of
dispersing, the concentration of the substance to be dispersed is
preferably set 20% or less of the total in mass ratio. Further, as
a substance in which the substance having a light-emitting property
is dispersed, a known substance can be used. It is preferable to
use a substance having a lowest unoccupied molecular orbital level
(LUMO level) deeper (the absolute value is larger) than that of the
substance having a light-emitting property and having a highest
occupied molecular orbital level (HOMO level) shallower (the
absolute value is smaller) than that of the substance having a
light-emitting property.
[0159] Specifically, any of the following metal complexes can be
used: tris(8-quinolinolato)aluminum(III) (abbreviation: Alq);
tris(4-methyl-8-quinolinolato)aluminum(III) (abbreviation:
Almq.sub.3); bis(10-hydroxybenzo[h]quinolinato)beryllium(II)
(abbreviation: BeBq.sub.2);
bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum(III)
(abbreviation: BAlq); bis(8-quinolinolato)zinc(II) (abbreviation:
Znq); bis[2-(2-benzoxazolyl)phenolato]zinc(II) (abbreviation:
ZnPBO); bis[2-(2-benzothiazolyl)phenolato]zinc(II) (abbreviation:
ZnBTZ); and the like.
[0160] In addition, any of the following heterocyclic compounds can
be used: 2-(biphenyl-4-yl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole
(abbreviation: PBD);
1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene
(abbreviation: OXD-7);
3-(biphenyl-4-yl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole
(abbreviation: TAZ);
2,2',2''-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole)
(abbreviation: TPBI); bathophenanthroline (abbreviation: BPhen);
bathocuproine (BCP); and the like.
[0161] Besides, any of the following condensed aromatic compounds
can also be used: 9-[4-(10-phenyl-9-anthryl)phenyl]-9H-Carbazole
(abbreviation: CzPA);
3,6-diphenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-Carbazole
(abbreviation: DPCzPA); 9,10-bis(3,5-diphenylphenyl)anthracene
(abbreviation: DPPA); 9,10-di(2-naphthyl)anthracene (abbreviation:
DNA); 2-tert-butyl-9,10-di(2-naphthyl)anthracene (abbreviation:
t-BuDNA); 9,9'-bianthryl (abbreviation: BANT);
9,9'-(stilbene-3,3'-diyl)diphenanthrene (abbreviation: DPNS);
9,9'-(stilbene-4,4'-diyl)diphenanthrene (abbreviation: DPNS2);
3,3',3''-(benzene-1,3,5-triyl)tripyrene (abbreviation: TPB3); and
the like.
[0162] As the substance in which the substance having a
light-emitting property is dispersed, a plurality of kinds of
substances can be used. For example, in order to suppress
crystallization, a substance for suppressing crystallization of
rubrene or the like may be further added. In addition, NPB, Alq, or
the like may be further added in order to efficiently transfer
energy to the substance having a light-emitting property. Thus,
with the structure in which the substance having a high
light-emitting property is dispersed in another substance,
crystallization of the third layer 113 can be suppressed. Further,
concentration quenching which results from the high concentration
of the substance having a high light-emitting property can be
suppressed.
[0163] Further, in particular, among the above substances, a
substance having an electron-transporting property is preferably
used so that the substance having a light-emitting property is
dispersed therein to form the third layer 113. Specifically, it is
also possible to use any of the above metal complexes and
heterocyclic compounds; CzPA, DNA, and t-BuDNA among the above
condensed aromatic compounds; and further macromolecular compounds
which will be given later as a substance that can be used for the
fourth layer 114.
[0164] Alternatively, for the third layer 113, the following
macromolecular compound can be used.
[0165] As a light-emitting substance for blue light emission,
poly(9,9-dioctylfluorene-2,7-diyl) (abbreviation: POF),
poly[(9,9-dioctylfluorene-2,7-diyl)-co-(2,5-dimethoxybenzen-1,4-diyl)]
(abbreviation: PF-DMOP),
poly{(9,9-dioctylfluorene-2,7-diyl)-co-[N,N'-di-(p-butylphenyl)-1,4-diami-
nobenzene]} (abbreviation: TAB-PFH), and the like can be given.
[0166] As a light-emitting substance for green light emission,
poly(p-phenylenvinylene) (abbreviation: PPV),
poly[(9,9-dihexylfluorene-2,7-diyl)-alt-co-(benzo[2,1,3]thiadiazol-4,7-di-
yl)] (abbreviation: PFBT),
poly[(9,9-dioctyl-2,7-divinylenfluorenylene)-alt-co-(2-methoxy-5-(2-ethyl-
hexyloxy)-1,4-phenylene)], and the like can be given.
[0167] As light-emitting substances for orange to red light
emission, poly[2-methoxy-5-(2'-ethylhexoxy)-1,4-phenylenevinylene]
(abbreviation: MEH-PPV), poly(3-butylthiophene-2,5-diyl)
(abbreviation: R4-PAT),
poly{[9,9-dihexyl-2,7-bis(1-cyanovinylene)fluorenylene]-alt-co-[2,5-bis(N-
,N'-diphenylamino)-1,4-phenylene]},
poly{[2-methoxy-5-(2-ethylhexyloxy)-1,4-bis(1-cyanovinylenephenylene)]-al-
t-co-[2,5-bis(N,N'-diphenylamino)-1,4-phenylene]} (abbreviation:
CN-PPV-DPD), and the like can be given.
[0168] The fourth layer 114 is an electron-transporting layer
containing a substance having a high electron-transporting
property. For the fourth layer 114, for example, as a low molecular
organic compound, a metal complex such as Alq, Almq.sub.3,
BeBq.sub.2, BAlq, Znq, ZnPBO, or ZnBTZ, or the like can be used.
Alternatively, instead of the metal complex, a heterocyclic
compound such as PBD, OXD-7, TAZ, TPBI, BPhen, or BCP can be used.
The substances described here are mainly substances having an
electron mobility of 10.sup.-6 cm.sup.2/Vs or more. Note that other
than the above substances may be used for the electron-transporting
layer as long as the substance has a higher electron-transporting
property than a hole-transporting property. Further, the
electron-transporting layer is not limited to a single layer but
may also be a stack layer of two or more layers formed of the above
substances.
[0169] Alternatively, for the fourth layer 114, a macromolecular
compound can be used. For example,
poly[(9,9-dihexylfluorene-2,7-diyl)-co-(pyridine-3,5-diyl)]
(abbreviation: PF-Py),
poly[(9,9-dioctylfluorene-2,7-diyl)-co-(2,2'-bipyridine-6,6'-diyl)]
(abbreviation: PF-BPy), or the like can be used.
[0170] Further, the fifth layer 115 is an electron-injecting layer
containing a substance having a high electron-injecting property.
For the fifth layer 115, an alkali metal, an alkaline earth metal,
or a compound thereof such as lithium fluoride (LiF), cesium
fluoride (CsF), or calcium fluoride (CaF.sub.2) can be used.
Alternatively, a layer formed of a substance having an
electron-transporting property which contains an alkali metal, an
alkaline earth metal, or a compound thereof, specifically, a layer
formed of Alq which contains magnesium (Mg), or the like may be
used. Note that in this case, electrons can be more efficiently
injected from a second electrode 104.
[0171] For the second electrode 104, a metal, an alloy, an
electrically conductive compound, a mixture thereof, or the like
having a low work function (specifically, a work function of 3.8 eV
or less) can be used. As a specific example of such a cathode
material, an element belonging to Group 1 or 2 of the periodic
table, that is, an alkali metal such as lithium (Li) or cesium
(Cs), an alkaline earth metal such as magnesium (Mg), calcium (Ca),
or strontium (Sr), an alloy containing any of these metals (such as
an MgAg alloy or an AlLi alloy), a rare-earth metal such as
europium (Eu) or ytterbium (Yb), an alloy containing such
rare-earth metals, and the like can be given.
[0172] Note that in the case where the second electrode 104 is
formed using an alkali metal, an alkaline-earth metal, or an alloy
thereof, a vacuum evaporation method or a sputtering method can be
employed. Note that in the case of using a silver paste or the
like, a coating method, an ink-jet method, or the like can be
used.
[0173] Note that by providing the fifth layer 115, the second
electrode 104 can be formed using any of a variety of conductive
materials such as Al, Ag, ITO, and indium tin oxide containing
silicon or silicon oxide regardless of their work functions. These
conductive materials can be formed by a sputtering method, an
inkjet method, a spin coating method, or the like.
[0174] Further, as a formation method of the EL layer 103 in which
the first layer (hole-injecting layer) 111, the second layer
(hole-transporting layer) 112, the third layer (light-emitting
layer) 113, the fourth layer (electron-transporting layer) 114, and
the fifth layer (electron-injecting layer) 115 are sequentially
stacked, any of a variety of methods can be employed regardless of
whether the method is a dry process or a wet process. For example,
a vacuum evaporation method, an ink-jet method, a spin coating
method, or the like can be used. Note that a different formation
method may be employed for each layer.
[0175] The second electrode 104 can also be formed by a wet process
such as a sol-gel method using a paste of a metal material in
addition to a dry process such as a sputtering method or a vacuum
evaporation method.
[0176] In the light-emitting element of the present invention
described above, current flows due to a potential difference
generated between the first electrode 102 and the second electrode
104 and holes and electrons recombine in the EL layer 103, whereby
light is emitted. Then, this light emission is extracted outside
through one of or both the first electrode 102 and the second
electrode 104. Therefore, one of or both the first electrode 102
and the second electrode 104 are an electrode having a
light-transmitting property.
[0177] Note that when only the first electrode 102 is an electrode
having a light-transmitting property, light emitted from the EL
layer 103 is extracted from the substrate 101 side through the
first electrode 102, as shown in FIG. 2A. Alternatively, when only
the second electrode 104 is an electrode having a
light-transmitting property, light emitted from the EL layer 103 is
extracted from the opposite side to the substrate 101 side through
the second electrode 104, as shown in FIG. 2B. Further
alternatively, when the first electrode 102 and the second
electrode 104 are both electrodes having a light-transmitting
property, light emitted from the EL layer 103 is extracted to both
the substrate 101 side and the opposite side to the substrate 101
side, through the first electrode 102 and the second electrode 104,
as shown in FIG. 2C.
[0178] The structure of the layers provided between the first
electrode 102 and the second electrode 104 is not limited to the
above. Structures other than the above may be employed as long as
at least the second layer 112 which is a hole-transporting layer
and the third layer 113 which is a light-emitting layer are
included.
[0179] Alternatively, as shown in FIG. 1B, a structure may be
employed in which the second electrode 104 which functions as a
cathode, the EL layer 103, and the first electrode 102 which
functions as an anode are sequentially stacked over the substrate
101. Note that the EL layer 103 in this case has a structure in
which the fifth layer 115, the fourth layer 114, the third layer
113, the second layer 112, the first layer 111, and the first
electrode 102 are sequentially stacked over the second electrode
104.
[0180] Note that by using the light-emitting element of the present
invention, a passive matrix light-emitting device or an active
matrix light-emitting device in which drive of the light-emitting
element is controlled by a thin film transistor (TFT) can be
manufactured.
[0181] Note that there is no particular limitation on the structure
of the TFT in the case of manufacturing an active matrix
light-emitting device. For example, a staggered TFT or an inverted
staggered TFT can be used as appropriate. Further, a driver circuit
formed over a TFT substrate may be formed of both an n-type TFT and
a p-type TFT or only either an n-type TFT or a p-type TFT.
Furthermore, there is no particular limitation on the crystallinity
of a semiconductor film used for the TFT. Either an amorphous
semiconductor film or a crystalline semiconductor film may be used
for the TFT.
[0182] Since the second layer (hole-transporting layer) 112 is
formed using the carbazole derivative of the present invention in
the light-emitting element which is shown in Embodiment Mode 2, not
only improvement in element efficiency but also suppress of
increase in drive voltage can be realized.
[0183] Note that Embodiment Mode 2 can be combined with any of the
structures described in Embodiment Mode 1 as appropriate.
Embodiment Mode 3
[0184] In Embodiment Mode 3, a light-emitting element having a
plurality of EL layers any of the light-emitting elements described
in Embodiment Mode 2 (hereinafter referred to as a stacked-type
light-emitting element) will be described with reference to FIG. 3.
This light-emitting element is a stacked-type light-emitting
element that has a plurality of EL layers (a first EL layer 303 and
a second EL layer 304) between a first electrode 301 and a second
electrode 302. Note that although a structure of two EL layers is
described in Embodiment Mode 3, a structure of three or more EL
layers may also be employed.
[0185] In Embodiment Mode 3, the first electrode 301 functions as
an anode, and the second electrode 302 functions as a cathode. Note
that for the first electrode 301 and the second electrode 302,
structures similar to those described in Embodiment Mode 1 can be
employed. Further, for the plurality of EL layers (the first EL
layer 303 and the second EL layer 304), structures similar to those
described in Embodiment Mode 2 can be employed. Note that
structures of the first EL layer 303 and the second EL layer 304
may be the same or different from each other and can be similar to
those described in Embodiment Mode 2.
[0186] Further, a charge generation layer 305 is provided between
the plurality of EL layers (the first EL layer 303 and the second
EL layer 304). The charge generation layer 305 has a function of
injecting electrons into one of the EL layers and injecting holes
into the other of the EL layers when voltage is applied to the
first electrode 301 and the second electrode 302. In Embodiment
Mode 3, when voltage is applied so that the potential of the first
electrode 301 is higher than that of the second electrode 302, the
charge generation layer 305 injects electrons into the first EL
layer 303 and injects holes into the second EL layer 304.
[0187] Note that the charge generation layer 305 preferably has a
light-transmitting property in terms of light extraction
efficiency. Further, the charge generation layer 305 functions even
when it has lower conductivity than the first electrode 301 or the
second electrode 302.
[0188] The charge generation layer 305 may have either a structure
in which a substance having an acceptor property is added to a
substance having a high hole-transporting property or a structure
in which a substance having a donor property is added to a
substance having a high electron-transporting property.
Alternatively, both of these structures may be stacked.
[0189] In the case of employing the structure in which a substance
having an acceptor property is added to a substance having a high
hole-transporting property, as the substance having a high
hole-transporting property, for example, an aromatic amine compound
such as 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl
(abbreviation: NPB or .alpha.-NPD), N N'-bis(3-methylphenyl)-N
N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviation: TPD),
4,4',4''-tris(N,N-diphenylamino)triphenylamine (abbreviation:
TDATA),
4,4',4''-tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine
(abbreviation: MTDATA), or
4,4'-bis[N-(spiro-9,9'-bifluoren-2-yl)-N-phenylamino]-1,1'-biphenyl
(abbreviation: BSPB) can be used. The substances described here are
mainly substances having a hole mobility of greater than or equal
to 10.sup.-6 cm.sup.2/Vs. Note that substances other than the
substances described above may also be used as long as the
hole-transporting properties thereof are higher than the
electron-transporting properties thereof.
[0190] In addition, as the substance having an acceptor property,
7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation:
F.sub.4-TCNQ), chloranil, and the like can be given. In addition, a
transition metal oxide can be given. Moreover, oxides of metals
belonging to Groups 4 to 8 of the periodic table can be given.
Specifically, vanadium oxide, niobium oxide, tantalum oxide,
chromium oxide, molybdenum oxide, tungsten oxide, manganese oxide,
and rhenium oxide are preferable because of a high
electron-accepting property. Among these, molybdenum oxide is
especially preferable because it is stable in the air and its
hygroscopic property is low so that it can be easily treated.
[0191] On the other hand, in the case of employing the structure in
which a substance having a donor property is added to a substance
having a high electron-transporting property, as the substance
having a high electron-transporting property, for example, a metal
complex having a quinoline skeleton or a benzoquinoline skeleton,
such as tris(8-quinolinolato)aluminum(III) (abbreviation: Alq),
tris(4-methyl-8-quinolinolato)aluminum(III) (abbreviation:
Almq.sub.3), bis(10-hydroxybenzo[h]quinolinato)beryllium(II)
(abbreviation: BeBq.sub.2), or
bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum(III)
(abbreviation: BAlq), can be used. Besides, a metal complex having
an oxazole-based ligand or a thiazole-based ligand, such as
bis[2-(2'-hydroxyphenyl)benzoxazolato]zinc(II) (abbreviation:
Zn(BOX).sub.2) or bis[2-(2'-hydroxyphenyl)benzothiazolato]zinc(II)
(abbreviation: Zn(BTZ).sub.2), can also be used. Further, other
than the metal complexes, any of the following can also be used:
2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole
(abbreviation: PBD);
1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene
(abbreviation: OXD-7);
3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole
(abbreviation: TAZ); bathophenanthroline (abbreviation: BPhen);
bathocuproine (BCP); or the like. The substances described here are
mainly substances having an electron mobility of 10.sup.-6
cm.sup.2/Vs or more. Note that other than the above substances may
be used as long as the substance has a higher electron-transporting
property than a hole-transporting property.
[0192] Further, for the substance having a donor property, an
alkali metal, an alkaline-earth metal, a rare-earth metal, a metal
belonging to Group 13 of the periodic table, or an oxide or
carbonate thereof can be used. Specifically, lithium (Li), cesium
(Cs), magnesium (Mg), calcium (Ca), ytterbium (Yb), indium (In),
lithium oxide, cesium carbonate, or the like is preferably used.
Alternatively, an organic compound such as tetrathianaphthacene may
be used as the substance having a donor property.
[0193] Note that by forming the charge generation layer 305 using
any of the above materials, increase in drive voltage in the case
where the EL layers are stacked can be suppressed.
[0194] Although the light-emitting element having two EL layers is
described in Embodiment Mode 3, the present invention can be
similarly applied to a light-emitting element in which three or
more EL layers are stacked. By arranging a plurality of EL layers
to be partitioned from each other with a charge generation layer
between a pair of electrodes, like the light-emitting element
according to Embodiment Mode 3, a long lifetime element in a high
luminance region can be realized while current density is kept low.
In a case where the light-emitting element is applied to lighting
as an application example, voltage drop due to resistance of an
electrode material can be reduced. Accordingly, light can be
uniformly emitted in a large area. Moreover, a light-emitting
device which consumes low power and is driven at low voltage can be
achieved.
[0195] Further, when the EL layers have different emission colors,
a desired emission color can be obtained from the whole
light-emitting element. For example, in the light-emitting element
having two EL layers, when an emission color of the first EL layer
and an emission color of the second EL layer are made to be
complementary colors, a light-emitting element emitting white light
as a whole light-emitting element can also be obtained. Note that
"complementary color" means a relation between colors which becomes
an achromatic color when they are mixed. That is, white light
emission can be obtained by mixture of lights obtained from
substances emitting the lights of complementary colors.
[0196] Also in a light-emitting element having three EL layers, for
example, white light as a whole light-emitting element can be
similarly obtained when an emission color of a first EL layer is
red, an emission color of a second EL layer is green, and an
emission color of a third EL layer is blue.
[0197] Note that Embodiment Mode 3 can be combined with any of the
structures described in Embodiment Modes 1 and 2 as
appropriate.
Embodiment Mode 4
[0198] In Embodiment Mode 4, a light-emitting device having the
light-emitting element of the present invention in a pixel portion
will be described with reference to FIGS. 4A and 4B. FIG. 4A is a
top view of the light-emitting device, and FIG. 4B is a cross
sectional view taken along A-A' and B-B' in FIG. 4A.
[0199] In FIG. 4A, reference numerals 401, 402, and 403 which are
shown by a dotted line denote a driver circuit portion (a source
driver circuit), a pixel portion, and a driver circuit portion (a
gate driver circuit), respectively. Reference numerals 404 and 405
denote a sealing substrate and a sealant, respectively, and an
inner side region enclosed by the sealant 405 is a space 407.
[0200] A lead wiring 408 is a wiring to transmit a signal to be
inputted to the source driver circuit portion 401 and the gate
driver circuit 403, and receives a video signal, a clock signal, a
start signal, a reset signal, and the like from a flexible printed
circuit (FPC) 409 which serves as an external input terminal.
Although only the FPC is shown here, this FPC may be provided with
a printed wiring board (PWB). Further, the light-emitting device in
this specification includes not only a light-emitting device itself
but also a light-emitting device attached with an FPC or a PWB.
[0201] Next, a cross-sectional structure of the light-emitting
device will be described with reference to FIG. 4B. The driver
circuit portion and the pixel portion are formed over an element
substrate 410. Here, one pixel in the pixel portion 402 and the
source driver circuit 401 which is the driver circuit portion are
shown. As the source driver circuit 401, a CMOS circuit which is
obtained by combining an n-channel TFT 423 and a p-channel TFT 424
is formed. The driver circuit may be formed by various CMOS
circuits, PMOS circuits, or NMOS circuits. In Embodiment Mode 4,
although a driver-integrated type structure in which a driver
circuit is formed over a substrate is described, a driver circuit
is not necessarily formed over a substrate but can be formed
externally from a substrate.
[0202] The pixel portion 402 is formed of a plurality of pixels
having a switching TFT 411, a current control TFT 412, and a first
electrode 413 electrically connected to a drain of the current
control TFT 412. An insulator 414 is formed to cover an end portion
of the first electrode 413.
[0203] The insulator 414 is preferably formed so as to have a
curved surface with curvature at an upper end portion or a lower
end portion thereof in order to obtain favorable coverage. For
example, by using positive-type photosensitive acrylic as a
material of the insulator 414, the insulator 414 can be formed to
have a curved surface with a curvature radius (0.2 .mu.m to 3
.mu.m) only at the upper end portion. Further, either a
negative-type photosensitive material which becomes insoluble in an
etchant by light irradiation or a positive-type photosensitive
material which becomes soluble in an etchant by light irradiation
can be used as the insulator 414.
[0204] An EL layer 416 and a second electrode 417 are formed over
the first electrode 413. Here, the first electrode 413 can be
formed using any of a variety of materials such as metals, alloys,
and electrically conductive compounds, or a mixture thereof. Note
that as specific materials, the materials which are shown in
Embodiment Mode 2 as a material that can be used for the first
electrode can be used.
[0205] In addition, the EL layer 416 is formed by any of a variety
of methods such as an evaporation method using an evaporation mask,
an ink-jet method, or a spin coating method. The EL layer 416 has
the structure described in Embodiment Mode 2. As another material
included in the EL layer 416, a low molecular compound or a
macromolecular compound (including an oligomer or a dendrimer) may
be used. As the material for the EL layer, not only an organic
compound but also an inorganic compound may also be used.
[0206] As a material for the second electrode 417, any of a variety
of metals, alloys, and electrically conductive compounds, or a
mixture thereof can be used. In the case where the second electrode
417 is used as a cathode, a metal, an alloy, an electrically
conductive compound, a mixture thereof, or the like with a low work
function (a work function of 3.8 eV or less) is preferably used,
among others. For example, an element belonging to Group 1 or 2 of
the periodic table, that is, an alkali metal such as lithium (Li)
or cesium (Cs), an alkaline-earth metal such as magnesium (Mg),
calcium (Ca), or strontium (Sr), or an alloy containing any of
these metals (such as a MgAg alloy or an AlLi alloy); and the like
can be given.
[0207] Note that in the case where light generated in the EL layer
416 is transmitted through the second electrode 417, for the second
electrode 417, a stack of a metal thin film with a reduced
thickness and a transparent conductive film (indium tin oxide
(ITO), indium tin oxide containing silicon or silicon oxide, indium
zinc oxide (IZO), or indium oxide containing tungsten oxide and
zinc oxide, or the like) can also be used.
[0208] By attaching the sealing substrate 404 and the element
substrate 410 with the sealant 405, there is a structure where a
light-emitting element 418 is provided in the space 407 surrounded
by the element substrate 410, the sealing substrate 404, and the
sealant 405. Note that the space 407 is filled with a filler such
as an inert gas (e.g., nitrogen, argon, or the like) or the sealant
405.
[0209] It is preferable to use an epoxy-based resin as the sealant
405. In addition, it is preferable that the material do not
transmit moisture and oxygen as much as possible. As a material for
the sealing substrate 404, a plastic substrate formed of FRP
(Fiberglass-Reinforced Plastics), PVF (polyvinyl fluoride),
polyester, acrylic, or the like can be used as well as a glass
substrate or a quartz substrate.
[0210] As described above, an active matrix light-emitting device
having the light-emitting element of the present invention can be
obtained.
[0211] Further, the light-emitting element of the present invention
can also be used for a passive matrix light-emitting device in
addition to the above active matrix light-emitting device. FIGS. 5A
and 5B respectively show a perspective view and a cross-sectional
view of a passive matrix light-emitting device using the
light-emitting element of the present invention. Note that FIG. 5A
is a perspective view of the light-emitting device, and FIG. 5B is
a cross-sectional view of FIG. 5A taken along line X-Y.
[0212] In FIGS. 5A and 5B, an EL layer 504 is provided between a
first electrode 502 and a second electrode 503 over a substrate
501. An edge portion of the first electrode 502 is covered with an
insulating layer 505. Then, a partition layer 506 is provided over
the insulating layer 505. Sidewalls of the partition layer 506 have
a slant such that a distance between one sidewall and the other
sidewall becomes narrower as the sidewalls gets closer to a surface
of the substrate. In other words, a cross section of the partition
layer 506 in the direction of a short side is trapezoidal, and a
lower base (a side facing a similar direction as a plane direction
of the insulating layer 505 and in contact with the insulating
layer 505) is shorter than an upper base (a side facing a similar
direction as the plane direction of the insulating layer 505 and
not in contact with the insulating layer 505). By providing the
partition layer 506 in such a manner, a defect of the
light-emitting element due to static electricity or the like can be
prevented.
[0213] Through the above process, the passive matrix light-emitting
device using the light-emitting element of the present invention
can be obtained.
[0214] Note that any of the light-emitting devices described in
Embodiment Mode 4 (the active matrix light-emitting device and the
passive matrix light-emitting device) are formed using the
light-emitting element of the present invention, which has high
luminous efficiency, and accordingly a light-emitting device having
reduced power consumption can be obtained.
[0215] Note that Embodiment Mode 4 can be combined with any of the
structures described in Embodiment Modes 1 to 3 as appropriate.
Embodiment Mode 5
[0216] In Embodiment Mode 5, an electronic device including, as
part thereof, the light-emitting device of the present invention
which is shown in Embodiment Mode 4 will be described. Examples of
the electronic device include cameras such as video cameras or
digital cameras, goggle type displays, navigation systems, audio
reproducing devices (e.g., car audio systems and audio components),
computers, game machines, portable information terminals (e.g.,
mobile computers, cellular phones, portable game machines, and
electronic books), image reproducing devices in which a recording
medium is provided (specifically, devices that are capable of
reproducing recording media such as digital versatile discs (DVDs)
and equipped with a display unit that can display images), and the
like. Specific examples of these electronic devices are shown in
FIGS. 6A to 6D.
[0217] FIG. 6A shows a television set according to the present
invention, which includes a housing 611, a supporting base 612, a
display portion 613, speaker portions 614, video input terminals
615, and the like. In this television set, the light-emitting
device of the present invention can be applied to the display
portion 613. Since the light-emitting device of the present
invention has a feature of high luminous efficiency, a television
set having reduced power consumption can be obtained by applying
the light-emitting device of the present invention.
[0218] FIG. 6B shows a computer according to the present invention,
which includes a main body 621, a housing 622, a display portion
623, a keyboard 624, an external connection port 625, a pointing
device 626, and the like. In this computer, the light-emitting
device of the present invention can be applied to the display
portion 623. Since the light-emitting device of the present
invention has a feature of high luminous efficiency, a computer
having reduced power consumption can be obtained by applying the
light-emitting device of the present invention.
[0219] FIG. 6C shows a cellular phone according to the present
invention, which includes a main body 631, a housing 632, a display
portion 633, an audio input portion 634, an audio output portion
635, operation keys 636, an external connection port 637, an
antenna 638, and the like. In this cellular phone, the
light-emitting device of the present invention can be applied to
the display portion 633. Since the light-emitting device of the
present invention has a feature of high luminous efficiency, a
cellular phone having reduced power consumption can be obtained by
applying the light-emitting device of the present invention.
[0220] FIG. 6D shows a camera according to the present invention,
which includes a main body 641, a display portion 642, a housing
643, an external connection port 644, a remote control receiving
portion 645, an image receiving portion 646, a battery 647, an
audio input portion 648, operation keys 649, an eyepiece portion
650, and the like. In this camera, the light-emitting device of the
present invention can be applied to the display portion 642. Since
the light-emitting device of the present invention has a feature of
high luminous efficiency, a camera having reduced power consumption
can be obtained by applying the light-emitting device of the
present invention.
[0221] As described above, the applicable range of the
light-emitting device of the present invention is so wide that the
light-emitting device can be applied to electronic devices in a
variety of fields.
[0222] The light-emitting device of the present invention can also
be used as a lighting device. FIG. 7 is an example of a liquid
crystal display device in which the light-emitting device of the
present invention is used as a backlight. The liquid crystal
display device shown in FIG. 7 includes a housing 701, a liquid
crystal layer 702, a backlight 703, and a housing 704. The liquid
crystal layer 702 is connected to a driver IC 705. The
light-emitting device of the present invention is used for the
backlight 703, and current is supplied through a terminal 706.
[0223] With the use of the light-emitting device of the present
invention as a backlight of a liquid crystal display device as
described above, a backlight which consumes low power can be
obtained. Further, since the light-emitting device of the present
invention is a plane emitting lighting device and the area thereof
can be enlarged, the backlight can also have a large area.
Therefore, a larger-area liquid crystal display device which
consumes low power can be obtained.
[0224] FIG. 8 shows an example of using the light-emitting device,
to which the present invention is applied, as a table lamp, which
is a lighting device. A table lamp shown in FIG. 8 has a housing
801 and a light source 802, and the light-emitting device of the
present invention is used as the light source 802. The
light-emitting device of the present invention has the
light-emitting element having high luminous efficiency and
therefore can be used as a desk lamp which consumes low power.
[0225] FIG. 9 shows an example of using the light-emitting device,
to which the present invention is applied, as an indoor lighting
device 901. Since the area of the light-emitting device of the
present invention can also be enlarged, the light-emitting device
of the present invention can be used as a lighting device having a
large area. In addition, the light-emitting device of the present
invention has the light-emitting element having high luminous
efficiency and therefore can be used as a lighting device which
consumes low power. When a television set 902 according to the
present invention as described in FIG. 6A is placed in a room in
which the light-emitting device, to which the present invention is
applied, is used as the indoor lighting device 901, public
broadcasting and movies can be watched.
[0226] Note that Embodiment Mode 5 can be combined with any of the
structures described in Embodiment Modes 1 to 4 as appropriate.
Embodiment 1
[0227] In Embodiment 1, a synthetic method of a carbazole
derivative of the present invention,
4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine
(abbreviation; PCBA1BP) represented by a structural formula (5),
will be specifically described.
##STR00114##
Step 1: Synthesis of 4-bromo-diphenylamine
[0228] A synthetic scheme of 4-bromo-diphenylamine in Step 1 is
shown in the following (D-1).
##STR00115##
[0229] After 51 g (0.3 mol) of diphenylamine was dissolved in 700
mL of ethyl acetate in a 1-L conical flask, 54 g (0.3 mol) of
N-bromo succinimide (abbreviation: NBS) was added to this solution.
About 300 hours later, this mixture solution was washed with water
and then magnesium sulfate was added thereto to remove moisture.
This mixture solution was filtrated, and the filtrate was
concentrated and collected. Accordingly, 70 g of a dark brown
oil-like object was obtained at a yield of 94%.
Step 2-1: Synthesis of 3-bromo-9-phenyl-9H-carbazole
[0230] A synthetic scheme of 3-bromo-9-phenyl-9H-carbazole in Step
2-1 is shown in the following (D-2-1).
##STR00116##
[0231] In a 1000 mL conical flask, 24 g (100 mmol) of
9-phenyl-9H-carbazole, 18 g (100 mmol) of N-bromo succinimide, 450
mL of toluene, and 200 mL of ethyl acetate were added, and the
mixture was stirred at room temperature for 45 hours. This
suspension was washed with water and then magnesium sulfate was
added thereto to remove moisture. This suspension was filtrated,
and the obtained filtrate was concentrated and dried. Accordingly,
32 g of a caramel-like object, 3-bromo-9-phenyl-9H-carbazole, was
obtained at a yield of 99%.
Step 2-2: Synthesis of 9-phenyl-9H-carbazol-3-boronic acid
[0232] A synthetic scheme of 9-phenyl-9H-carbazol-3-boronic acid in
Step 2-2 is shown in the following (D-2-2).
##STR00117##
[0233] In a 500-mL conical flask, 29 g (90 mmol) of
3-bromo-9-phenyl-9H-carbazole and 200 mL of tetrahydrofuran (THF)
were stirred at -78.degree. C. to be a solution. After that, 110 mL
(69 mmol) of n-butyllithium (a 1.57 mol/L hexane solution) was
dropped into this solution and was stirred at the same temperature
for 2 hours. Further, 13 mL (140 mmol) of trimethyl borate was
added to this solution, and the solution was stirred at room
temperature for 24 hours.
[0234] After completion of the reaction, 200 mL of hydrochloric
acid (1.0 mol/L) was added to the reaction mixture, and then the
mixture was stirred at room temperature for 1 hour. This mixture
was washed with a sodium hydroxide aqueous solution and water in
this order, and magnesium sulfate was added to remove moisture.
This suspension was filtrated, the obtained filtrate was
concentrated, and chloroform and hexane were added thereto. The
mixture was irradiated with supersonic. After that,
recrystallization was performed. Accordingly, 21 g of an objective
white powder, 9-phenyl-9H-carbazol-3-boronic acid, was obtained at
a yield of 80%.
Step 3: Synthesis of 4-(9-phenyl-9H-carbazol-3-yl)diphenylamine
(Abbreviation: PCBA)
[0235] A synthetic scheme of
4-(9-phenyl-9H-carbazol-3-yl)diphenylamine (abbreviation: PCBA) in
Step 3 is shown in the following (D-3).
##STR00118##
[0236] In a 500-mL three-neck flask, 6.5 g (26 mmol) of
4-bromodiphenylamine, 7.5 g (26 mmol) of
9-phenyl-9H-carbazol-3-boronic acid, and 400 mg (1.3 mmol) of
tri(o-tolyl)phosphine were put, and the atmosphere in the flask was
substituted by nitrogen. Then, 100 mL of toluene, 50 mL of ethanol,
and 14 mL of potassium carbonate solution (0.2 mol/L) were added to
this mixture. This mixture was deaerated while being stirred under
low pressure. After the deaeration, 67 mg (30 mmol) of
palladium(II) acetate was added thereto.
[0237] This mixture was refluxed at 100.degree. C. for 10 hours.
After the reflux, the aqueous layer of this mixture was extracted
with toluene. Then, the extracted solution was combined with an
organic layer, followed by washing with a saturated saline
solution. After the moisture of the organic layer was removed by
magnesium sulfate, this mixture was naturally filtrated, and the
obtained filtrate was concentrated to obtain an oily light-brown
substance. This oily substance was purified by silica gel column
chromatography (developing solvent, hexane: toluene=4:6). A white
solid which was obtained after the purification was recrystallized
with dichloromethane/hexane, and 4.9 g of an objective white solid
was obtained at a yield of 45%.
Step 4: Synthesis of
4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine
(Abbreviation: PCBA1BP)
[0238] A synthetic scheme of
4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine
(abbreviation: PCBA1BP) in Step 4 is shown in the following
(D-4).
##STR00119##
[0239] In a 100-mL three-neck flask, 2.0 g (4.9 mmol) of
4-(9-phenyl-9H-carbazol-3-yl)diphenylamine, 1.1 g (4.9 mmol) of
4-bromobiphenyl, and 2.0 g (20 mmol) of sodium tert-butoxide were
put, and the atmosphere in the flask was substituted by nitrogen.
Then, 50 mL of toluene and 0.30 mL of tri(tert-butyl)phosphine (10
wt % hexane solution) were added to this mixture.
[0240] This mixture was deaerated while being stirred under low
pressure. After the deaeration, 0.10 g of
bis(dibenzylideneacetone)palladium(0) was added thereto. Next, this
mixture was stirred at 80.degree. C. for 5 hours to be reacted.
After the reaction, toluene was added to the reaction mixture, and
suction filtration was performed on this suspension through Celite,
alumina, and then Florisil to obtain filtrate. The obtained
filtrate was washed with a saturated sodium carbonate solution and
a saturated saline solution in this order. Magnesium sulfate was
added to the organic layer, and the organic layer was dried. After
the drying, suction filtration was performed on this mixture to
remove the magnesium sulfate; thus, the filtrate was obtained.
[0241] The obtained filtrate was concentrated and purified by
silica gel column chromatography. The silica gel column
chromatography was performed by, first, using a mixture solvent of
toluene:hexane=1:9 as a developing solvent, and then using a
mixture solvent of toluene:hexane=3:7 as another developing
solvent. A solid which was obtained by concentrating the obtained
fraction was recrystallized with a mixture solvent of chloroform
and hexane to obtain 2.3 g of a white powder-like solid at a yield
of 84%.
[0242] Sublimation purification of 1.2 g of the obtained white
solid was performed by a train sublimation method. The sublimation
purification was performed under a reduced pressure of 7.0 Pa, with
a flow rate of argon at 3 mL/min, at 280.degree. C. for 20 hours.
Accordingly, 1.1 g of the white solid was obtained at a yield of
89%.
[0243] A compound which was obtained through the above Step 4 was
measured by a nuclear magnetic resonance method (.sup.1H NMR). The
measurement result is described below, and the .sup.1H NMR chart is
shown in FIGS. 10A and 10B. It was found from the measurement
result that the carbazole derivative of the present invention,
4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine
(abbreviation: PCBA1BP) represented by the above structural formula
(5), was obtained.
[0244] .sup.1H NMR (DMSO-d, 300 MHz): .delta. (ppm)=7.05-7.20 (m,
7H), 7.28-7.78 (m, 21H), 8.34 (d, J=7.8 Hz, 1H), 8.57 (s, 1H).
[0245] In addition, an absorption spectrum of a toluene solution of
PCBA1BP (abbreviation) is shown in FIG. 11A. In addition, an
absorption spectrum of a thin film of PCBA1BP (abbreviation) is
shown in FIG. 11B. An ultraviolet-visible spectrophotometer (V-550,
manufactured by JASCO Corporation) was used for the measurement.
The spectrum of the solution was measured in a quartz cell. The
sample of the thin film was fabricated by vapor evaporation of
PCBA1BP (abbreviation) over a quartz substrate. The absorption
spectrum of the solution which was obtained by subtracting the
quartz cell from the measured sample is shown in FIG. 11A, and the
absorption spectrum of the thin film which was obtained by
subtracting the quartz substrate from the measured sample is shown
in FIG. 11B.
[0246] In FIGS. 11A and 11B, the horizontal axis indicates the
wavelength (nm) and the vertical axis indicates the absorption
intensity (arbitrary unit). In the case of the toluene solution, an
absorption peak was observed at around 335 nm, and in the case of
the thin film, an absorption peak was observed at around 341 nm. In
addition, an emission spectrum of the toluene solution (excitation
wavelength: 346 nm) of PCBA1BP (abbreviation) is shown in FIG. 11A.
In addition, an emission spectrum of the thin film (excitation
wavelength: 386 nm) of PCBA1BP (abbreviation) is shown in FIG. 11B.
In FIGS. 11A and 11B, the horizontal axis indicates the wavelength
(nm) and the vertical axis indicates the light emission intensity
(arbitrary unit). The maximum emission wavelength was 391 nm
(excitation wavelength: 346 nm) in the case of the toluene solution
and 416 nm (excitation wavelength: 386 nm) in the case of the thin
film.
[0247] An oxidation-reduction reaction characteristic of PCBA1BP
(abbreviation) was examined by a cyclic voltammetry (CV)
measurement. An electrochemical analyzer (ALS model 600A or 600C,
manufactured by BAS Inc.) was used for the measurement.
[0248] As for a solution used in the CV measurement, dehydrated
dimethylformamide (DMF) (manufactured by Aldrich, 99.8%, catalog
number: 22705-6) was used as a solvent, and tetra-n-butylammonium
perchlorate (n-Bu.sub.4NClO.sub.4, product of Tokyo Chemical
Industry Co., Ltd., catalog No. T0836), which was a supporting
electrolyte, was dissolved in the solvent such that the
concentration thereof was 100 mmol/L. Further, the object to be
measured was also dissolved in the solvent such that the
concentration thereof was 2 mmol/L. A platinum electrode (PTE
platinum electrode, manufactured by BAS Inc.) was used as a working
electrode, another platinum electrode (Pt counter electrode for
VC-3 (5 cm), manufactured by BAS Inc.) was used as an auxiliary
electrode, and an Ag/Ag.sup.+ electrode (RE7 reference electrode
for nonaqueous solvent, manufactured by BAS Inc.) was used as a
reference electrode. Note that the measurement was performed at
room temperature (20.degree. C. to 25.degree. C.). In addition, the
scan speed at the CV measurement was 0.1 V/sec.
(Calculation of the Potential Energy of the Reference Electrode
with Respect to the Vacuum Level)
[0249] First, potential energy (eV) of the reference electrode
(Ag/Ag.sup.+ electrode) used in Embodiment 1 with respect to the
vacuum level was calculated. That is, the Fermi level of the
Ag/Ag.sup.+ electrode was calculated. It is known that the
oxidation-reduction potential of ferrocene in methanol is +0.610 V
[vs. SHE] with respect to a standard hydrogen electrode (Reference:
Christian R. Goldsmith et al., J. Am. Chem. Soc., Vol. 124, No. 1,
pp. 83-96, 2002). On the other hand, the oxidation-reduction
potential of ferrocene in methanol measured by using the reference
electrode used in Embodiment 1 was found to be +0.11 V [vs.
Ag/Ag.sup.+]. Therefore, it was found that the potential energy of
the reference electrode used in Embodiment 1 was less than that of
the standard hydrogen electrode by 0.50 [eV].
[0250] Here, it is also known that the potential energy of the
standard hydrogen electrode with respect to the vacuum level is
(-4.44 eV (Reference: Toshihiro Ohnishi and Tamami Koyama,
Macromolecular EL material, Kyoritsu Shuppan, pp. 64-67). As
described above, the potential energy of the reference electrode
used in Embodiment 1 with respect to the vacuum level was
calculated to be -4.44-0.50=-4.94 [eV].
[0251] FIG. 41 shows the CV measurement result on the oxidation
reaction characteristics. Note that the measurement of the
oxidation reaction characteristics was performed by the steps of
scanning the potential of the working electrode with respect to the
reference electrode in ranges of (1) 0.07 V to 1.00 V, and then (2)
1.00 V to 0.07 V
[0252] First, the calculation of the HOMO level of PCBA1BP
(abbreviation) by CV measurement is described in detail. As shown
in FIG. 41, an oxidization peak potential E.sub.pa was 0.536 V. In
addition, a reduction peak potential E.sub.pc was 0.446 V.
Therefore, a half-wave potential (an intermediate potential between
E.sub.pc and E.sub.pa) can be calculated to be 0.49 V. This shows
that PCBA1BP (abbreviation) can be oxidized by an electrical energy
of 0.49 V [vs. Ag/Ag.sup.+], and this energy corresponds to the
HOMO level. Here, the potential energy of the reference electrode
used in Embodiment 1 with respect to the vacuum level is -4.94 [eV]
as described above. Therefore, the HOMO level of PCBA1BP
(abbreviation) was found to be -4.94-0.49=-5.43 [eV]. In addition,
the oxidation peak took a similar value even after the 100 cycles.
Accordingly, it was found that repetition of the oxidation
reduction between an oxidation state and a neutral state had
favorable characteristics.
Embodiment 2
[0253] In Embodiment 2, a synthetic method of a carbazole
derivative of the present invention,
4,4'-diphenyl-4''-(9-phenyl-9-H-carbazol-3-yl)triphenylamine
(abbreviation: PCBBi1BP) represented by a structural formula (6),
will be specifically described.
##STR00120##
Step 1-1: Synthesis of 4-phenyl-diphenylamine
[0254] A synthetic scheme of 4-phenyl-diphenylamine in Step 1-1 is
shown in the following (E-1-1).
##STR00121##
[0255] In a three-neck flask, 5.2 g (2.5 mmol) of
tri-tert-butylphosphine (10 wt % hexane solution) was added to a
dehydrated xylene suspension (150 mL) containing 20.0 g (85.8 mmol)
of 4-bromobiphenyl, 16.0 g (172 mmol) of aniline, 0.19 g (0.86
mmol) of palladium(II) acetate, and 23.7 g (172 mmol) of potassium
carbonate, and a mixture thereof was refluxed under a nitrogen
atmosphere at 120.degree. C. for 10 hours. After completion of the
reaction, the reaction mixture was washed with water and separated
into an organic layer and an aqueous layer, and the aqueous layer
was extracted with toluene.
[0256] The above obtained toluene layer was combined with the above
organic layer, followed by washing with a saturated saline
solution. Then, magnesium sulfate was added thereto to remove
moisture in the organic layer. Suction filtration was performed on
this mixture to concentrate the obtained filtrate. The obtained
residue was purified by silica gel column chromatography (a
developing was solvent: toluene). Accordingly, 13.5 g of a white
solid of 4-phenyl-diphenylamine, which was obtained by
concentrating the obtained solution, was obtained at a yield of
64%.
Step 1-2: Synthesis of 4,4'-diphenyltriphenylamine
[0257] A synthetic scheme of 4,4'-diphenyltriphenylamine in Step
1-2 is shown in the following (E-1-2).
##STR00122##
[0258] In a 100-mL three-neck flask, 3.7 g (15 mmol) of
4-phenyl-diphenylamine, 3.5 g (15 mmol) of 4-bromobiphenyl, 2.5 g
(25 mmol) of sodium tert-butoxide, and 10 mg (0.02 mmol) of
bis(dibenzylideneacetone)palladium(0) were put, and the atmosphere
in the flask was substituted by nitrogen. Then, 40 mL of dehydrated
xylene was added to this mixture. The mixture was deaerated while
being stirred under low pressure. After the deaeration, 0.2 mL (60
mmol) of tri(tert-butyl)phosphine (10 wt % hexane solution) was
added thereto.
[0259] Next, this mixture was stirred at 120.degree. C. for 5
hours, to be reacted. After the reaction, toluene was added to the
reaction mixture, and suction filtration was performed on this
suspension through Celite, alumina, and then Florisil to obtain
filtrate. The obtained filtrate was washed with a saturated sodium
carbonate solution and a saturated saline solution in this order.
Magnesium sulfate was added to the obtained organic layer to remove
moisture. Suction filtration was performed on this mixture through
Celite, alumina, and then Florisil to concentrate the obtained
filtrate. Acetone and methanol were added to the obtained residue,
and the residue was irradiated with supersonic and then
recrystallized to obtain 5.4 g of a white powder-like solid at a
yield of 92%.
Step 1': Synthesis of 4,4'-diphenyltriphenylamine
[0260] In addition to Step 1-1 and Step 1-2 which are described
above, 4,4'-diphenyltriphenylamine can also be synthesized using a
synthetic method shown in Step 1'. Note that a synthetic scheme of
4,4'-diphenyltriphenylamine in Step 1' is shown in the following
(E-1').
##STR00123##
[0261] In a 200-mL three-neck flask, 1.9 g (20 mmol) of aniline,
9.3 g (40 mmol) of 4-bromobiphenyl, 4.5 g (45 mmol) of sodium
tert-butoxide, 0.4 g (2.0 mmol) of palladium(II) acetate, and 1.1 g
(2.0 mmol) of 1,1-bis(diphenylphosphino)ferrocene (abbreviation:
DPPF) were put, and the atmosphere in the flask was substituted by
nitrogen. Then, 70 mL of dehydrated xylene was added to this
mixture. This mixture was deaerated while being stirred under low
pressure, and the mixture was stirred at 110.degree. C. for 3 hours
to be reacted. After the reaction, toluene was added to the
reaction mixture, and suction filtration was performed on this
suspension through Celite, alumina, and then Florisil to obtain
filtrate. The obtained filtrate was washed with a saturated sodium
carbonate solution and a saturated saline solution in this ordel
Magnesium sulfate was added to the obtained organic layer to remove
moisture. Suction filtration was performed on this mixture through
Celite, alumina, and then Florisil to concentrate the obtained
filtrate. Acetone and hexane were added to the obtained residue,
and the residue was irradiated with supersonic and then
recrystallized to obtain 5.4 g of a white powder-like solid at a
yield of 67%.
Step 2: Synthesis of 4-bromo-4',4''-diphenyltriphenylamine
[0262] With the use of Step 1-1 and Step 1-2 which are described
above, or 4,4'-diphenyltriphenylamine which was synthesized using a
synthetic method shown in Step 1',
4-bromo-4',4''-diphenyltriphenylamine is synthesized. Note that a
synthetic scheme of 4-bromo-4',4''-diphenyltriphenylamine in Step 2
is shown in the following (E-2).
##STR00124##
[0263] After 4.0 g (10 mmol) of 4,4'-diphenyltriphenylamine was
dissolved in a mixture solvent of 50 mL of toluene and 50 mL of
ethyl acetate in a conical flask, N-bromo succinimide
(abbreviation: NBS) was added to this solution. After that, this
mixture was stirred at room temperature for 120 hours. After
completion of the reaction, this mixture solution was washed with
water, and magnesium sulfate was added thereto to remove moisture.
This mixture solution was filtrated and the obtained filtrate was
concentrated to perform recrystallization. Accordingly, 4.5 g of an
objective white powder was obtained at a yield of 95%.
Step 3: Synthesis of
4,4'-diphenyl-4''-(9-phenyl-9-H-carbazol-3-yl)triphenylamine
(Abbreviation: PCBBi1BP)
[0264] A synthetic scheme of
4,4'-diphenyl-4''-(9-phenyl-9-H-carbazol-3-yl)triphenylamine
(abbreviation: PCBBi1BP) in Step 3 is shown in the following
(E-3).
##STR00125##
[0265] In a 100-mL three-neck flask, 1.5 g (3.1 mmol) of
4-bromo-4',4''-diphenyltriphenylamine, 0.9 g (3.1 mmol) of
9-phenyl-9H-carbazol-3-boronic acid, 50 mg (0.023 mmol) of
palladium(II) acetate, and 0.050 g (0.17 mmol) of
tri(o-tolyl)phosphine were put, and the atmosphere in the flask was
substituted by nitrogen. Note that since a synthetic method of
9-phenyl-9H-carbazol-3-boronic acid is similar to that described in
Embodiment 1, the description is to be referred thereto; thus,
description here is omitted. 30 mL of ethyleneglycoldimethylether
(DME) and 15 mL of potassium carbonate solution (2 mol/L) were
added to this mixture. This mixture was deaerated while being
stirred under low pressure. After the deaeration, this mixture was
stirred at 90.degree. C. for 5 hours to be reacted.
[0266] After the reaction, ethyl acetate was added to the reaction
mixture, and this suspension was washed with a saturated sodium
hydrogen carbonate solution and a saturated saline solution.
Magnesium sulfate was added to an organic layer, and the organic
layer was dried. After the drying, suction filtration was performed
on this mixture to remove the magnesium sulfate; thus, filtrate was
obtained. Toluene was added to a solid which was obtained by
concentrating the obtained filtrate and the mixture was dissolved.
Then, suction filtration was performed on this solution through
Celite, alumina and Florisil to obtain filtrate. The obtained
filtrate was concentrated and purified by silica gel column
chromatography. The silica gel column chromatography was performed
by, first, using a mixture solvent of toluene:hexane=1:9 as a
developing solvent, and then using a mixture solvent of
toluene:hexane=3:7 as another developing solvent.
[0267] A solid which was obtained by concentrating the obtained
fraction was recrystallized with a mixture solvent of
dichloromethane and hexane to obtain 1.3 g of an objective white
solid at a yield of 66%. Sublimation purification of 1.1 g of the
obtained white solid was performed by a train sublimation method.
The sublimation purification was performed under a reduced pressure
of 7.0 Pa, with a flow rate of argon at 4 mL/min, at 305.degree. C.
for 15 hours. Accordingly, 840 mg of the white solid was obtained
at a yield of 76%.
[0268] A compound which was obtained through the above Step 4 was
measured by a nuclear magnetic resonance method (.sup.1H NMR). The
measurement result is described below, and the .sup.1H NMR chart is
shown in FIGS. 12A and 12B. It was found from the measurement
result that the carbazole derivative of the present invention,
4,4'-diphenyl-4''-(9-phenyl-9-H-carbazol-3-yl)triphenylamine
(abbreviation: PCBBi1BP) represented by the above structural
formula (6), was obtained.
[0269] .sup.1H NMR (CDCl.sub.3, 300 MHz): .delta. (ppm)=7.25-7.69
(m, 32H), 8.19 (d, J=7.3 Hz, 1H), 8.35 (s, 1H).
[0270] In addition, an absorption spectrum of a toluene solution of
PCBBi1BP (abbreviation) is shown in FIG. 13A. In addition, an
absorption spectrum of a thin film of PCBBi1BP (abbreviation) is
shown in FIG. 13B. An ultraviolet-visible spectrophotometer (V-550,
manufactured by JASCO Corporation) was used for the measurement.
The spectrum of the solution was measured in a quartz cell. The
sample of the thin film was fabricated by vapor evaporation of
PCBBi1BP (abbreviation) over a quartz substrate. The absorption
spectrum of the solution which was obtained by subtracting the
quartz cell from the measured sample is shown in FIG. 13A, and the
absorption spectrum of the thin film which was obtained by
subtracting the quartz substrate from the measured sample is shown
in FIG. 13B. In FIGS. 13A and 13B, the horizontal axis indicates
the wavelength (nm) and the vertical axis indicates the absorption
intensity (arbitrary unit). In the case of the toluene solution, an
absorption peak was observed at around 347 nm, and in the case of
the thin film, an absorption peak was observed at around 350 nm. In
addition, an emission spectrum of the toluene solution (excitation
wavelength: 358 nm) of PCBBi1BP (abbreviation) is shown in FIG.
13A. In addition, an emission spectrum of the thin film (excitation
wavelength: 366 nm) of PCBBi1BP (abbreviation) is shown FIG. 13B.
In FIGS. 13A and 13B, the horizontal axis indicates the wavelength
(nm) and the vertical axis indicates the light emission intensity
(arbitrary unit). The maximum emission wavelength was 399 nm
(excitation wavelength: 358 nm) in the case of the toluene solution
and 417 nm (excitation wavelength: 366 nm) in the case of the thin
film.
[0271] An oxidation-reduction reaction characteristic of PCBBi1BP
(abbreviation) was examined by a cyclic voltammetry (CV)
measurement. Since the measurement method is similar to that of
Embodiment 1, the description is omitted.
[0272] FIG. 42 shows the CV measurement result on the oxidation
reaction characteristics. As shown in FIG. 42, an oxidization peak
potential E.sub.pa can be read as 0.521 V, and a reduction peak
potential E.sub.pc can be read as +0.431 V. Therefore, a half-wave
potential (an intermediate potential between E.sub.pc and E.sub.pa)
can be calculated to be +0.48 V. According to the calculation
similar to that of Embodiment 1, the HOMO level of PCBBi1BP
(abbreviation) was found to be=-5.42 [eV]. In addition, the
oxidation peak took a similar value even after the 100 cycles.
Accordingly, it was found that repetition of the oxidation
reduction between an oxidation state and a neutral state had
favorable characteristics.
[0273] The result of measuring the thin film using a photoelectron
spectrometer (AC-2, manufactured by Riken Keiki Co., Ltd.) under
the atmosphere indicated that the HOMO level of PCBBi1BP
(abbreviation) was -5.34 eV. The Tauc plot of the absorption
spectrum of the thin film revealed that the absorption edge was
3.15 eV. Thus, the energy gap in the solid state was estimated to
be 3.15 eV, which means that the LUMO level of PCBBi1BP
(abbreviation) is -2.19 eV.
[0274] In addition, the glass transition temperature of PCBBi1BP
(abbreviation) was examined with a differential scanning
calorimetry (Pyris 1 DSC, manufactured by Perkin Elmer Co., Ltd.).
According to the measurement results, it was found that the glass
transition temperature was 123.degree. C. In this manner, PCBBi1BP
(abbreviation) has a high glass transition temperature and
favorable heat resistance. In addition, the crystallization peak
does not exist; thus, it was found that PCBBi1BP (abbreviation) is
a substance which is hard to be crystallized.
Embodiment 3
[0275] In Embodiment 3, a synthetic method of a carbazole
derivative of the present invention,
9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-fluorene-2--
amine (abbreviation: PCBAF) represented by a structural formula
(7), will be specifically described.
##STR00126##
Step 1: Synthesis of 2-bromo-9,9-dimethylfluoren
[0276] A synthetic scheme of 2-bromo-9,9-dimethylfluoren in Step 1
is shown in the following (F-1).
##STR00127##
[0277] In a 500-mL conical flask, 12.5 g (51 mmol) of
2-bromofluorene, 8.5 g (51 mmol) of potassium iodide, 14.3 g (0.50
mol) of potassium hydroxide, and 250 mL of dimethyl sulfoxide were
stirred for 30 minutes. Then, 10 mL of methyl iodide was added to
this mixture little by little. This mixture was stirred at room
temperature for 48 hours. After the reaction, 400 mL of chloroform
was added to the reaction solution and this mixture was stirred.
This solution was washed with 1N hydrochloric acid, a saturated
sodium carbonate solution, and a saturated saline solution in this
order. Magnesium sulfate was added to the obtained organic layer to
remove moisture.
[0278] This mixture was subjected to suction filtration and
concentrated. Then, a residue thereof was purified by silica gel
column chromatography. The silica gel column chromatography was
performed by, first, using hexane as a developing solvent, and then
using a mixture solvent of ethyl acetate:hexane=1:5 as another
developing solvent. The corresponding fractions were concentrated
and dried to obtain 12 g of a brown oily substance at a yield of
97%.
Step 2: Synthesis of
9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-fluorene-2--
amine (Abbreviation: PCBAF)
[0279] A synthetic scheme of
9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-fluorene-2--
amine (abbreviation: PCBAF) in Step 2 is shown in the following
(F-2).
##STR00128##
[0280] In a 100-mL three-neck flask, 2.0 g (4.9 mmol) of
4-(9-phenyl-9H-carbazol-3-yl)diphenylamine (abbreviation: PCBA),
1.3 g (4.9 mmol) of 2-bromo-9,9-dimethylfluoren, and 2.0 g (20
mmol) of sodium tert-butoxide were put, and the atmosphere in the
flask was substituted by nitrogen. Note that since a synthetic
method of PCBA (abbreviation) is similar to that described in
Embodiment 2, the description is to be referred thereto; thus,
description here is omitted. Then, 50 mL of toluene and 0.30 mL of
tri(tert-butyl)phosphine (10 wt % hexane solution) were added to
this mixture. The mixture was deaerated while being stirred under
low pressure. After the deaeration, 0.10 g of
bis(dibenzylideneacetone)palladium(0) was added thereto. Next, the
mixture was stirred at 80.degree. C. for 5 hours to be reacted.
After the reaction, toluene was added to the reaction mixture, and
suction filtration was performed on this suspension through Celite,
alumina, and then Florisil to obtain filtrate.
[0281] The obtained filtrate was concentrated and purified by
silica gel column chromatography. The silica gel column
chromatography was performed by, first, using a mixture solvent of
toluene:hexane=1:9 as a developing solvent, and then using a
mixture solvent of toluene:hexane=3:7 as another developing
solvent. A solid which was obtained by concentrating the obtained
fraction was recrystallized with a mixture solvent of chloroform
and hexane to obtain 1.3 g of an objective compound at a yield of
44%.
[0282] Sublimation purification of 1.3 g of the obtained light
yellow solid was performed by a train sublimation method. The
sublimation purification was performed under a reduced pressure of
7.0 Pa, with a flow rate of argon at 3 mL/min, at 270.degree. C.
for 20 hours. Accordingly, 1.0 g of the light yellow solid was
obtained at a yield of 77%.
[0283] A compound which was obtained through the above Step 2 was
measured by a nuclear magnetic resonance method (.sup.1H NMR). The
measurement result is described below, and the .sup.1H NMR chart is
shown in FIGS. 14A and 14B. It was found from the measurement
result that the carbazole derivative of the present invention,
9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-fluorene-2--
amine (abbreviation: PCBAF) represented by the above structural
formula (7), was obtained.
[0284] .sup.1H NMR (DMSO-d, 300 MHz): .delta. (ppm)=1.39 (s, 6H)
6.98-7.82 (m, 26H), 8.35 (d, J=6.8 Hz, 1H), 8.57 (s, 1H).
[0285] In addition, an absorption spectrum of a toluene solution of
PCBAF (abbreviation) is shown in FIG. 15A. In addition, an
absorption spectrum of a thin film of PCBAF (abbreviation) is shown
in FIG. 15B. An ultraviolet-visible spectrophotometer (V-550,
manufactured by JASCO Corporation) was used for the measurement.
The spectrum of the solution was measured in a quartz cell. The
sample of the thin film was fabricated by vapor evaporation of
PCBAF (abbreviation) over a quartz substrate. The absorption
spectrum of the solution which was obtained by subtracting the
quartz cell from the measured sample is shown in FIG. 15A, and the
absorption spectrum of the thin film which was obtained by
subtracting the quartz substrate from the measured sample is shown
in FIG. 15B. In FIGS. 15A and 15B, the horizontal axis indicates
the wavelength (nm) and the vertical axis indicates the absorption
intensity (arbitrary unit). In the case of the toluene solution, an
absorption peak was observed at around 339 nm, and in the case of
the thin film, an absorption peak was observed at around 345 nm. In
addition, an emission spectrum of the toluene solution (excitation
wavelength: 347 nm) of PCBAF (abbreviation) is shown in FIG. 15A.
In addition, an emission spectrum of the thin film (excitation
wavelength: 370 nm) of PCBAF (abbreviation) is shown FIG. 15B. In
FIGS. 15A and 15B, the horizontal axis indicates the wavelength
(nm) and the vertical axis indicates the light emission intensity
(arbitrary unit). The maximum emission wavelength was 394 nm
(excitation wavelength: 347 nm) in the case of the toluene solution
and 404 nm (excitation wavelength: 370 nm) in the case of the thin
film.
[0286] An oxidation-reduction reaction characteristic of PCBAF
(abbreviation) was examined by a cyclic voltammetry (CV)
measurement. Since the measurement method is similar to that of
Embodiment 1, the description is omitted.
[0287] FIG. 43 shows the CV measurement result on the oxidation
reaction characteristics. As shown in FIG. 43, an oxidization peak
potential E.sub.pa can be read as 0.481 V, and a reduction peak
potential E.sub.pc can be read as +0.393 V. Therefore, a half-wave
potential (an intermediate potential between E.sub.pc and E.sub.pa)
can be calculated to be +0.44 V. According to the calculation
similar to that of Embodiment 1, the HOMO level of PCBAF
(abbreviation) was found to be=-5.38 [eV]. In addition, the
oxidation peak took a similar value even after the 100 cycles.
Accordingly, it was found that repetition of the oxidation
reduction between an oxidation state and a neutral state had
favorable characteristics.
Embodiment 4
[0288] In Embodiment 4, a synthetic method of a carbazole
derivative of the present invention,
N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-spiro-9,9'-bifluoren-2-a-
mine (abbreviation: PCBASF) represented by a structural formula
(8), will be specifically described.
##STR00129##
Step 1-1: Synthesis of 9-(biphenyl-2-yl)-2-bromofluoren-9-ol
[0289] A synthetic scheme of 9-(biphenyl-2-yl)-2-bromofluoren-9-ol
in Step 1-1 is shown in the following (G-1-1).
##STR00130##
[0290] In a 100-mL three-neck flask to which a dropping funnel and
a Dimroth condenser were connected, 1.26 g (0.052 mol) of magnesium
was put, and the flask was evacuated. The magnesium was activated
by heating and stirring for 30 minutes. After cooling to room
temperature, the flask was placed under a nitrogen gas flow. Then,
5 mL of diethyl ether and several drops of dibromoethane were added
thereto, and 11.65 g (0.050 mol) of 2-bromobiphenyl dissolved in 15
mL of diethyl ether was slowly dropped from the dropping funnel
into the mixture. After completion of the dropping, the mixture was
refluxed for 3 hours and made into a Grignard reagent.
[0291] In a 200-mL three-neck flask to which a dropping funnel and
a Dimroth condenser were connected, 11.7 g (0.045 mol) of
2-bromo-9-fluorenone and 40 mL of diethyl ether were put. To this
reaction solution, the synthesized Grignard reagent was slowly
dropped from the dropping funnel. After completion of the dropping,
the mixture was refluxed for 2 hours, and then stirred at room
temperature overnight. After completion of the reaction, the
solution was washed twice with a saturated ammonia chloride
solution, and separated into an aqueous layer and an organic layer.
The obtained aqueous layer was extracted twice with ethyl acetate,
and this ethyl acetate solution and the obtained organic layer were
washed with a saturated saline solution. After moisture was removed
by magnesium sulfate, suction filtration and concentration were
performed to obtain 18.76 g of a solid of
9-(biphenyl-2-yl)-2-bromo-9-fluorenol at a yield of 90%.
Step 1-2: Synthesis of 2-bromo-spiro-9,9'-bifluoren
[0292] A synthetic scheme of 2-bromo-spiro-9,9'-bifluoren in Step
1-2 is shown in the following (G-1-2).
##STR00131##
[0293] In a 200-mL three-neck flask, 18.76 g (0.045 mol) of the
synthesized 9-(biphenyl-2-yl)-2-bromo-9-fluorenol and 100 mL of
glacial acetic acid were put, several drops of concentrated
hydrochloric acid were added thereto, and the mixture was refluxed
for 2 hours. After completion of the reaction, a precipitate was
collected by suction filtration, and the precipitate was filtered
and washed with a saturated sodium hydrogen carbonate solution and
water. The obtained brown solid was recrystallized with ethanol to
obtain 10.24 g of a light-brown powder-like solid at a yield of
57%.
Step 2: Synthesis of
N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-spiro-9,9'-bifluoren-2-a-
mine (Abbreviation: PCBASF)
[0294] A synthetic scheme of
N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-spiro-9,9'-bifluoren-2-a-
mine (abbreviation: PCBASF) in Step 2 is shown in the following
(G-2).
##STR00132##
[0295] In a 100-mL three-neck flask, 2.0 g (4.9 mmol) of
4-(9-phenyl-9H-carbazol-3-yl)diphenylamine (abbreviation: PCBA),
1.9 g (4.9 mmol) of 2-bromo-spiro-9,9'-bifluoren, and 2.0 g (20
mmol) of sodium tert-butoxide were put, and the atmosphere in the
flask was substituted by nitrogen. Then, 50 mL of toluene and 0.30
mL of tri(tert-butyl)phosphine (10 wt % hexane solution) were added
to this mixture. This mixture was deaerated while being stirred
under low pressure. After the deaeration, 0.10 g of
bis(dibenzylideneacetone)palladium(0) was added thereto.
[0296] Next, this mixture was stirred at 80.degree. C. for 5 hours
to be reacted. After the reaction, toluene was added to the
reaction mixture, and suction filtration was performed on this
suspension through Celite, alumina, and then Florisil to obtain
filtrate. The obtained filtrate was washed with a saturated sodium
carbonate solution and a saturated saline solution in this order.
After magnesium sulfate was added to an organic layer to remove
moisture, suction filtration was performed on this mixture and the
magnesium sulfate was removed to obtain filtrate. A solid which was
obtained by concentrating the obtained filtrate was recrystallized
with a mixture solvent of chloroform and hexane to obtain 3.4 g of
a white powder-like solid at a yield of 94%. Sublimation
purification of 2.3 g of the obtained white solid was performed by
a train sublimation method. The sublimation purification was
performed under a reduced pressure of 7.0 Pa, with a flow rate of
argon at 3 mL/min, at 310.degree. C. for 20 hours. Accordingly, 1.7
g of the white solid was obtained at a yield of 74%.
[0297] A compound which was obtained through the above Step 2 was
measured by a nuclear magnetic resonance method (.sup.1H NMR). The
measurement result is described below, and the .sup.1H NMR chart is
shown in FIGS. 16A and 16B. It was found from the measurement
result that the carbazole derivative of the present invention,
N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-spiro-9,9'-bifluoren-2-a-
mine (abbreviation: PCBASF) represented by the above structural
formula (8), was obtained.
[0298] .sup.1H NMR (CDCl.sub.3, 300 MHz): .delta. (ppm)=6.61-6.70
(m, 2H), 6.83 (d, J=8.3 Hz, 2H), 6.88-7.79 (m, 30H), 8.16 (d, J=8.3
Hz, 1H), 8.26 (s, 1H).
[0299] In addition, an absorption spectrum of a toluene solution of
PCBASF (abbreviation) is shown in FIG. 17A. In addition, an
absorption spectrum of a thin film of PCBASF (abbreviation) is
shown in FIG. 17B. An ultraviolet-visible spectrophotometer (V-550,
manufactured by JASCO Corporation) was used for the measurement.
The spectrum of the solution was measured in a quartz cell. The
sample of the thin film was fabricated by vapor evaporation of
PCBASF (abbreviation) over a quartz substrate. The absorption
spectrum of the solution which was obtained by subtracting the
quartz cell from the measured sample is shown in FIG. 17A, and the
absorption spectrum of the thin film which was obtained by
subtracting the quartz substrate from the measured sample is shown
in FIG. 17B. In FIGS. 17A and 17B, the horizontal axis indicates
the wavelength (nm) and the vertical axis indicates the absorption
intensity (arbitrary unit). In the case of the toluene solution, an
absorption peak was observed at around 338 nm, and in the case of
the thin film, an absorption peak was observed at around 345 nm. In
addition, an emission spectrum of the toluene solution (excitation
wavelength: 352 nm) of PCBASF (abbreviation) is shown in FIG. 17A.
In addition, an emission spectrum of the thin film (excitation
wavelength: 371 nm) of PCBASF (abbreviation) is shown FIG. 17B. In
FIGS. 17A and 17B, the horizontal axis indicates the wavelength
(nm) and the vertical axis indicates the light emission intensity
(arbitrary unit). The maximum emission wavelength was 396 nm
(excitation wavelength: 352 nm) in the case of the toluene solution
and 427 nm (excitation wavelength: 371 nm) in the case of the thin
film.
[0300] An oxidation-reduction reaction characteristic of PCBASF
(abbreviation) was examined by a cyclic voltammetry (CV)
measurement. Since the measurement method is similar to that of
Embodiment 1, the description is omitted.
[0301] FIG. 44 shows the CV measurement result on the oxidation
reaction characteristics. As shown in FIG. 44, an oxidization peak
potential E.sub.pa can be read as 0.52 V, and a reduction peak
potential E.sub.pc can be read as +0.428 V. Therefore, a half-wave
potential (an intermediate potential between E.sub.pc and E.sub.pa)
can be calculated to be +0.47 V. According to the calculation
similar to that of Embodiment 1, the HOMO level of PCBASF
(abbreviation) was found to be=-5.41 [eV]. In addition, the
oxidation peak took a similar value even after the 100 cycles.
Accordingly, it was found that repetition of the oxidation
reduction between an oxidation state and a neutral state had
favorable characteristics.
Embodiment 5
[0302] In Embodiment 5, a method for manufacturing a light-emitting
element 2, a light-emitting element 3, a light-emitting element 4,
and a light-emitting element 5, which were formed using carbazole
derivatives of the present invention that are synthesized in
Embodiments 1 to 4 and measurement results of their element
characteristics will be described. The light-emitting element 2 was
formed using 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine
(abbreviation: PCBA1BP), the light-emitting element 3 was formed
using 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine
(abbreviation: PCBBi1BP), the light-emitting element 4 was formed
using
9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-fluorene-2--
amine (abbreviation: PCBAF), and the light-emitting element 5 was
formed using
N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-spiro-9,9'-bifluor-
en-2-amine (abbreviation: PCBASF).
[0303] Note that each element structure of the light-emitting
elements in Embodiment 5 is a structure shown in FIG. 18, in which
a hole-transporting layer 1512 is formed using the above carbazole
derivative of the present invention. In addition, a light-emitting
element 1 which is a comparative light-emitting element is formed
using 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation:
NPB) for the hole-transporting layer 1512. In order to make
comparative conditions of the light-emitting element 1 with each of
the light-emitting elements 2 to 5 the same, the light-emitting
element 1 was formed over the same substrates as the light-emitting
elements 2 to 5, and the light-emitting element 1 was compared to
the light-emitting elements 2 to 5. A structural formula of an
organic compound used in Embodiment 5 is shown below.
##STR00133## ##STR00134##
[0304] First, indium tin oxide containing silicon oxide was
deposited over a substrate 1501 which is a glass substrate by a
sputtering method to form a first electrode 1502. The thickness of
the first electrode 1502 was set to be 110 nm, and the area was set
to be 2 mm.times.2 mm.
[0305] Next, an EL layer 1503 in which a plurality of layers are
stacked over the first electrode 1502 was formed. In Embodiment 5,
the EL layer 1503 has a structure in which a first layer 1511 which
is a hole-injecting layer, a second layer 1512 which is a
hole-transporting layer, a third layer 1513 which is a
light-emitting layer, a fourth layer 1514 which is an
electron-transporting layer, and a fifth layer 1515 which is an
electron-injecting layer are sequentially stacked.
[0306] The substrate having the first electrode 1502 was fixed to a
substrate holder provided in a vacuum evaporation apparatus in such
a way that the surface of the first electrode 1502 faced downward,
and then the pressure was reduced to about 10.sup.-4 Pa. Then,
4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB)
and molybdenum(VI) oxide were co-evaporated on the first electrode
1502, whereby the first layer 1511 which is a hole-injecting layer
was formed. The evaporation rate was controlled so that the
thickness of the first layer which is a hole-injecting layer could
be 50 nm and the weight ratio of NPB to molybdenum(VI) oxide could
be 4:1 (=NPB: molybdenum oxide). Note that the co-evaporation
method is an evaporation method in which evaporation is performed
using a plurality of evaporation sources at the same time in one
treatment chamber.
[0307] Next, a hole-transporting material was deposited over the
first layer 1511 to a thickness of 10 nm by an evaporation method
using resistive heating, and the second layer 1512 which is a
hole-transporting layer was formed. Note that
4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB)
was used in the case of forming the light-emitting element 1,
4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine
(abbreviation: PCBA1BP) was used in the case of forming the
light-emitting element 2,
4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine
(abbreviation: PCBBi1BP) was used in the case of forming the
light-emitting element 3,
9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-fluorene-2--
amine (abbreviation: PCBAF) was used in the case of forming the
light-emitting element 4, and
N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-spiro-9,9-bifluoren-2-am-
ine (abbreviation: PCBASF) were used in the case of forming the
light-emitting element 5.
[0308] Next, the third layer 1513 which is a light-emitting layer
was formed over the second layer 1512 by an evaporation method
using resistive heating. The third layer 1513 was formed by
co-evaporating 9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole
(abbreviation: CzPA) and
4-(10-phenyl-9-anthryl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine
(abbreviation: PCBAPA) to a thickness of 30 nm. Here, the
evaporation rate was controlled so that the weight ratio of CzPA to
PCBAPA could be 1:0.10 (=CzPA: PCBAPA).
[0309] Further, tris(8-quinolinolato)aluminum(III) (abbreviation:
Alq) was deposited over the third layer 1513 to be a thickness of
10 nm by an evaporation method using resistive heating. Then, the
fourth layer 1514 which is an electron-transporting layer was
formed by depositing bathophenanthroline (abbreviation: BPhen) over
the third layer 1513 to a thickness of 20 nm.
[0310] Then, the fifth layer 1515 which is an electron-injecting
layer was formed by depositing lithium fluoride (LiF) to a
thickness of 1 nm over the fourth layer 1514.
[0311] Finally, a second electrode 1504 was formed by depositing
aluminum to a thickness of 200 nm by an evaporation method using
resistance heating, and the light-emitting elements 1 to 5 were
formed.
[0312] The light-emitting elements 1 to 5 obtained through the
process described above were put into a glove box with a nitrogen
atmosphere so that the light-emitting elements were sealed without
being exposed to atmospheric air. After that, the operating
characteristics of these light-emitting elements were measured.
Note that the measurement was performed at room temperature (an
atmosphere kept at 25.degree. C.).
[0313] FIG. 19 shows the current density vs. luminance
characteristics of the light-emitting elements 1 and 2. FIG. 20
shows the voltage vs. luminance characteristics of the
light-emitting elements 1 and 2. FIG. 21 shows the luminance vs.
current efficiency characteristics of the light-emitting elements 1
and 2. FIG. 22 shows the voltage vs. current characteristics of the
light-emitting elements 1 and 2.
[0314] When the drive voltage of the light-emitting element 2 was
3.4 V, the luminance and the current value were 1277 cd/m.sup.2 and
0.79 mA, respectively. It was found that the light-emitting element
2 using PCBA1BP (abbreviation) for the second layer 1512 showed
higher luminance, even when the light-emitting element 2 was
compared to the light-emitting element 1 using NPB for the second
layer 1512. Further, it was found that the current efficiency was
high with respect to the current density or the luminance.
[0315] In addition, in the light-emitting element 2, an emission
wavelength derived from PCBAPA which is a blue light-emitting
material was observed but an emission wavelength derived from the
hole-transporting material was not observed from emission spectrum
shown in FIG. 23. Thus, it was found that favorable carrier balance
was realized in the structure of the light-emitting element 2 using
PCBA1BP (abbreviation) of the present invention.
[0316] FIG. 24 shows the results of a continuous lighting test in
which the light-emitting element 2 was continuously lit by constant
current driving with the initial luminance set at 1000 cd/m.sup.2
(the vertical axis indicates the relative luminance on the
assumption that 1000 cd/m.sup.2 is 100%). From the results in FIG.
24, the light-emitting element 2 exhibits 92% of the initial
luminance even after 160 hours, and was found to have a longer
lifetime, as compared to the light-emitting element 1. Thus, a long
lifetime light-emitting element can be obtained by applying PCBA1BP
(abbreviation) of the present invention.
[0317] FIG. 25 shows the current density vs. luminance
characteristics of the light-emitting elements 1 and 3. FIG. 26
shows the voltage vs. luminance characteristics of the
light-emitting elements 1 and 3. FIG. 27 shows the luminance vs.
current efficiency characteristics of the light-emitting elements 1
and 3. FIG. 28 shows the voltage vs. current characteristics of the
light-emitting elements 1 and 3.
[0318] When the drive voltage of the light-emitting element 3 was
3.4 V, the luminance and the current value were 1328 cd/m.sup.2 and
0.78 mA, respectively. It was found that the light-emitting element
3 using PCBBi1BP (abbreviation) for the second layer 1512 showed
higher luminance, even when the light-emitting element 3 was
compared to the light-emitting element 1 using NPB for the second
layer 1512. Further, it was found that the current efficiency was
high with respect to the current density or the luminance.
[0319] In addition, in the light-emitting element 3, an emission
wavelength derived from PCBAPA which is a blue light-emitting
material was observed but an emission wavelength derived from the
hole-transporting material was not observed from emission spectrum
shown in FIG. 29. Thus, it was found that favorable carrier balance
was realized in the structure of the light-emitting element 3 using
PCBBi1BP (abbreviation) of the present invention.
[0320] FIG. 30 shows the current density vs. luminance
characteristics of the light-emitting elements 1 and 4. FIG. 31
shows the voltage vs. luminance characteristics of the
light-emitting elements 1 and 4. FIG. 32 shows the luminance vs.
current efficiency characteristics of the light-emitting elements 1
and 4. FIG. 33 shows the voltage vs. current characteristics of the
light-emitting elements 1 and 4.
[0321] When the drive voltage of the light-emitting element 4 was
3.8 V, the luminance and the current value were 1328 cd/m.sup.2 and
1.08 mA, respectively. It was found that the light-emitting element
4 using PCBAF (abbreviation) for the second layer 1512 showed
higher luminance, even when the light-emitting element 4 was
compared to the light-emitting element 1 using NPB for the second
layer 1512.
[0322] In addition, in the light-emitting element 4, an emission
wavelength derived from PCBAPA which is a blue light-emitting
material was observed but an emission wavelength derived from the
hole-transporting material was not observed from emission spectrum
shown in FIG. 34. Thus, it was found that favorable carrier balance
was realized in the structure of the light-emitting element 4 using
PCBAF (abbreviation) of the present invention.
[0323] FIG. 35 shows the results of a continuous lighting test in
which the light-emitting element 4 was continuously lit by constant
current driving with the initial luminance set at 1000 cd/m.sup.2
(the vertical axis indicates the relative luminance on the
assumption that 1000 cd/m.sup.2 is 100%). From the results in FIG.
35, the light-emitting element 4 exhibits 92% of the initial
luminance even after 160 hours and was found to have a longer
lifetime, as compared to the light-emitting element 1. Thus, a long
lifetime light-emitting element can be obtained by applying PCBAF
(abbreviation) of the present invention.
[0324] FIG. 36 shows the current density vs. luminance
characteristics of the light-emitting elements 1 and 5. FIG. 37
shows the voltage vs. luminance characteristics of the
light-emitting elements 1 and 5. FIG. 38 shows the luminance vs.
current efficiency characteristics of the light-emitting elements 1
and 5. FIG. 39 shows the voltage vs. current characteristics of the
light-emitting elements 1 and 5.
[0325] When the drive voltage of the light-emitting element 5 was
3.8 V, the luminance and the current value were 1398 cd/m.sup.2 and
1.11 mA, respectively. It was found that the light-emitting element
5 using PCBASF (abbreviation) for the second layer 1512 showed
higher luminance, even when the light-emitting element 5 was
compared to the light-emitting element 1 using NPB for the second
layer 1512. Further, it was found that the current efficiency was
high with respect to the current density or the luminance.
[0326] In addition, in the light-emitting element 5, an emission
wavelength derived from PCBAPA which is a blue light-emitting
material was observed but an emission wavelength derived from the
hole-transporting material was not observed from emission spectrum
shown in FIG. 40. Thus, it was found that favorable carrier balance
was realized in the structure of the light-emitting element 5 using
PCBASF (abbreviation) of the present invention.
[0327] As described above, it was found that the light-emitting
elements 2 to 5 which were formed using the carbazole derivatives
of the present invention exhibited an equivalent level of
efficiency to the light-emitting element 1. Thus, it was found that
a light-emitting element having high efficiency can be obtained by
applying the present invention.
[0328] In addition, as another structure of the light-emitting
element 1 shown in Embodiment 5, PCBA1BP (abbreviation) was used
instead of NPB (abbreviation), which was used at the time of
forming the first layer 1511, and was co-evaporated with
molybdenum(VI) oxide to form the first layer 1511. With the
efficiency, the drive voltage at a luminance of about 1000
cd/m.sup.2, and the reliability of such a light-emitting element 1,
favorable values equivalent to those of a light-emitting element 8
were obtained. The light-emitting element 8 will be formed in
Embodiment 10 by using a co-evaporation film of NPB and
molybdenum(VI) oxide for a hole-injecting layer and using PCBBiNB
(abbreviation) for a hole-transporting layer. When the drive
voltage of the light-emitting element 1 was 3.8 V, the luminance
and the current value were 949 cd/m.sup.2 and 0.65 mA,
respectively, and the light-emitting element 1 exhibited 64% of the
initial luminance when driven for 1500 hours.
[0329] As thus described, it was found that PCBA1BP (abbreviation)
was a favorable material also as a hole-injecting material. In
addition, it was found that favorable characteristics can also be
obtained by using the co-evaporation film with molybdenum(VI) oxide
for the hole-injecting layer.
[0330] In addition, as another structure of the light-emitting
element 2 shown in Embodiment 5, PCBA1BP (abbreviation) was used
instead of NPB (abbreviation), which was used at the time of
forming the first layer 1511, and was co-evaporated with
molybdenum(VI) oxide to form the first layer 1511. With the
efficiency, the drive voltage at a luminance of about 1000
cd/m.sup.2, and the reliability of such a light-emitting element 2,
favorable values equivalent to those of a light-emitting element 8
were obtained. The light-emitting element 8 will be formed in
Embodiment 10 by using a co-evaporation film of NPB and
molybdenum(VI) oxide for a hole-injecting layer and using PCBBiNB
(abbreviation) for a hole-transporting layer. When the drive
voltage of the light-emitting element 2 was 3.6 V, the luminance
and the current value were 843 cd/m.sup.2 and 0.53 mA,
respectively, and the light-emitting element 2 exhibited 65% of the
initial luminance when driven for 1500 hours.
[0331] As thus described, it was found that PCBA1BP (abbreviation)
was a favorable material which can be used for both the first layer
1511 which is a hole-injecting layer and the second layer 1512
which is a hole-transporting layer at the same time. Accordingly,
an element could be manufactured easily and material use efficiency
could also be improved.
Embodiment 6
[0332] In Embodiment 6, a synthetic method of a carbazole
derivative of the present invention,
(biphenyl-4-yl)(phenyl)[4'-(9-phenyl-9H-carbazol-3-yl)biphenyl-4-yl]amine
(abbreviation: PCTA1BP) represented by a structural formula (15),
will be specifically described.
##STR00135##
Step 1: Synthesis of
4-[N-(biphenyl-4-yl)-N-phenyl]aminophenylboronic Acid
[0333] A synthetic scheme of
4-[N-(biphenyl-4-yl)-N-phenyl]aminophenylboronic acid in Step 1 is
shown in the following (H-1).
##STR00136##
[0334] In a 300-mL three-neck flask, 7.0 g (18 mmol) of
4-bromo-4'-phenyltriphenylamine was put, and the atmosphere in the
flask was substituted by nitrogen. Then, 80 mL of tetrahydrofuran
(abbreviation: THF) was added thereto, and the mixture was stirred
at -78.degree. C. for 10 minutes. After that, 13 mL (21 mmol) of an
n-butyllithium hexane solution (1.63 mol/L) was dropped onto this
solution from a syringe, and the solution was stirred at
-78.degree. C. for 1 hour. After the stirring, 3.5 mL (31 mmol) of
trimethyl borate was added to the reaction mixture, and the mixture
was stirred at -78.degree. C. for 1 hour and at room temperature
for 24 hours. After the reaction, 100 mL of 1M dilute hydrochloric
acid was added to the reaction solution, and the mixture was
stirred at room temperature for 1 hour. After the stirring, this
solution was extracted with ethyl acetate, and an organic layer was
washed with a saturated saline solution. After the washing,
magnesium sulfate was added to the organic layer, and the organic
layer was dried. After the drying, magnesium sulfate was removed by
suction filtration to obtain filtrate. The obtained filtrate was
concentrated and recrystallized with a mixture solvent of
chloroform and hexane to obtain 3.6 g of an object at a yield of
56%.
Step 2: Synthesis of
(biphenyl-4-yl)(phenyl)[4'-(9-phenyl-9H-carbazol-3-yl)biphenyl-4-yl]amine
(Abbreviation: PCTA1BP)
[0335] A synthetic scheme of
(biphenyl-4-yl)(phenyl)[4'-(9-phenyl-9H-carbazol-3-yl)biphenyl-4-yl]amine
in Step 2 is shown in the following (H-2).
##STR00137##
[0336] In a 100-mL three-neck flask, 2.2 g (5.5 mmol) of
4-[N-(biphenyl-4-yl)-N-phenyl]aminophenylboronic acid, 2.0 g (5.5
mmol) of 3-(4-bromophenyl)-9-phenyl-9H-carbazole, 10 mg (0.045
mmol) of palladium(II) acetate, and 0.69 g (0.23 mmol) of
tri(o-tolyl)phosphine were put, and 10 mL of a potassium carbonate
solution (2.0 mol/L) and 20 mL of ethylene glycol dimethyl ether
(abbreviation: DME) were added thereto. This mixture was deaerated
while being stirred under low pressure, and the atmosphere in the
flask was substituted by nitrogen. This mixture was stirred at
90.degree. C. for 5 hours. After the stirring, toluene was added to
the reaction mixture, and the mixture was heated at 90.degree.
C.
[0337] After the heating, this suspension was separated into an
organic layer and an aqueous layer. After the separation, the
organic layer was washed with a saturated sodium hydrogen carbonate
solution and a saturated saline solution. Magnesium sulfate was
added to the organic layer, and the organic layer was dried.
Suction filtration was performed on this mixture through Celite,
alumina, and then Florisil to obtain filtrate. The obtained
filtrate was concentrated to obtain a solid. The obtained filtrate
was dissolved and purified by silica gel column chromatography. The
silica gel column chromatography was performed by, first, using a
mixture solvent of toluene: hexane=1:9 as a developing solvent, and
then using a mixture solvent of toluene:hexane=2:3 as another
developing solvent. A solid which was obtained by concentrating the
obtained fraction was dissolved in chloroform and purified by high
performance liquid chromatography (HPLC) (developing solvent,
chloroform). A solid which was obtained by concentrating the
obtained fraction was recrystallized with a mixture solvent of
chloroform and hexane to obtain 1.7 g of an objective white solid
at a yield of 48%.
[0338] Sublimation purification of 1.0 g of the obtained white
solid was performed by a train sublimation method. The sublimation
purification was performed under a reduced pressure of 7.0 Pa, with
a flow rate of argon at 4 mL/min, at 300.degree. C. for 15 hours to
obtain 0.62 g of the white solid at a yield of 62%.
[0339] A compound which was obtained through the above Step 2 was
measured by a nuclear magnetic resonance method (.sup.1H NMR). The
measurement result is described below, and the .sup.1H NMR chart is
shown in FIGS. 45A and 45B. It was found from the measurement
result that the carbazole derivative of the present invention,
PCTA1BP (abbreviation) represented by the above structural formula
(15), was obtained. .sup.1H NMR (CDCl.sub.3, 300 MHz): .delta.
(ppm)=7.02-7.79 (m, 32H), 8.19 (d, J=7.3 Hz, 1H), 8.39 (s, 1H).
[0340] In addition, an absorption spectrum of PCTA1BP
(abbreviation) (measurement range: 200 nm to 800 nm) was measured.
In the case of the toluene solution, an absorption peak on a long
wavelength side was observed at around 349 nm, and in the case of
the thin film, an absorption peak on a long wavelength side was
observed at around 357 nm.
[0341] In addition, an emission spectrum of PCTA1BP (abbreviation)
(measurement range: 370 nm to 550 nm) was measured. In the case of
the toluene solution, a maximum emission wavelength was 405 nm
(excitation wavelength: 320 nm), and in the case of the thin film,
a maximum emission wavelength was 420 nm (excitation wavelength:
284 nm). Since the measurement method of an absorption spectrum and
an emission spectrum is similar to that of Embodiment 1, the
description is omitted.
[0342] The result of measuring the thin film using a photoelectron
spectrometer (AC-2, manufactured by Riken Keiki Co., Ltd.) under
the atmosphere indicated that the HOMO level of PCTA1BP
(abbreviation) was -5.49 eV. The Tauc plot of the absorption
spectrum of the thin film revealed that the absorption edge was
3.10 eV. Thus, the energy gap in the solid state was estimated to
be 3.10 eV, which means that the LUMO level of PCTA1BP
(abbreviation) is -2.39 eV.
[0343] An oxidation-reduction reaction characteristic of PCTA1BP
(abbreviation) was examined by a cyclic voltammetry (CV)
measurement. Since the measurement method is similar to that of
Embodiment 1, the description is omitted. According to the
calculation similar to that of Embodiment 1, the HOMO level of
PCTA1BP (abbreviation) was found to be=-5.48 [eV]. In addition, the
oxidation peak took a similar value even after the 100 cycles.
Accordingly, it was found that repetition of the oxidation
reduction between an oxidation state and a neutral state had
favorable characteristics.
[0344] In addition, the glass transition temperature of PCTA1BP
(abbreviation) was examined with a differential scanning
calorimetry (Pyris 1 DSC, manufactured by Perkin Elmer Co., Ltd.).
According to the measurement results, it was found that the glass
transition temperature was 118.degree. C. In this manner, PCTA1BP
(abbreviation) has a high glass transition temperature and
favorable heat resistance. In addition, the crystallization peak
does not exist; thus, it was found that PCTA1BP (abbreviation) is a
substance which is hard to be crystallized.
[0345] Note that with the efficiency, the drive voltage at a
luminance of about 1000 cd/m.sup.2, and the reliability of a
light-emitting element formed using PCTA1BP (abbreviation) which
was synthesized in Embodiment 6 in a manner similar to that of
Embodiment 5 for a hole-transporting layer, favorable values
equivalent to those of a light-emitting element 8 which will be
formed using PCBBiNB in Embodiment 10 were obtained. When the drive
voltage of the light-emitting element was 3.6 V, the luminance and
the current value were 1044 cd/m.sup.2 and 0.67 mA, respectively,
and the light-emitting element exhibited 52% of the initial
luminance when driven for 1100 hours.
Embodiment 7
[0346] In Embodiment 7, a synthetic method of a carbazole
derivative of the present invention,
bis(biphenyl-4-yl)[4'-(9-phenyl-9H-carbazol-3-yl)biphenyl-4-yl]amine
(abbreviation: PCTBi1BP) represented by a structural formula (190),
will be specifically described.
##STR00138##
Step 1: Synthesis of 4-[(bis(biphenyl-4-yl)amino]phenylboronic
Acid
[0347] A synthetic scheme of
4-[bis(biphenyl-4-yl)amino]phenylboronic acid in Step 1 is shown in
the following (I-1).
##STR00139##
[0348] In a 300-mL three-neck flask, 6.0 g (13 mmol) of
4-bromo-4',4''-diphenyltriphenylamine was put, and the atmosphere
in the flask was substituted by nitrogen. Then, 80 mL of
tetrahydrofuran (abbreviation: THF) was added thereto, and the
mixture was stirred at -78.degree. C. for 10 minutes. After that,
10 mL of an n-butyllithium hexane solution (1.63 mol/L) was dropped
onto this solution from a syringe, and the solution was stirred at
-78.degree. C. for 1 hour. After the stirring, 2.8 mL (25 mmol) of
trimethyl borate was added to the reaction mixture, and the mixture
was stirred at -78.degree. C. for 1 hour and further at room
temperature for 24 hours. After the stirring, about 50 mL of dilute
hydrochloric acid was added to the reaction mixture, and the
mixture was stirred at room temperature for 30 minutes. After the
stirring, ethyl acetate was added to this mixture to perform
extraction. After the extraction, an organic layer was washed with
a saturated saline solution. Then, magnesium sulfate was added to
the organic layer, and the organic layer was dried. After the
drying, suction filtration was performed on this mixture to obtain
filtrate. The obtained filtrate was concentrated and recrystallized
with a mixture solvent of chloroform and hexane to obtain 4.8 g of
an objective white powder-like solid at a yield of 86%.
Step 2: Synthesis of
bis(biphenyl-4-yl)[4'-(9-phenyl-9H-carbazol-3-yl)biphenyl-4-yl]amine
(Abbreviation: PCTBi1BP)
[0349] A synthetic scheme of
bis(biphenyl-4-yl)[4'-(9-phenyl-9H-carbazol-3-yl)biphenyl-4-yl]amine
in Step 2 is shown in the following (1-2).
##STR00140##
[0350] In a 100-mL three-neck flask, 2.0 g (4.5 mmol) of
4-[bis(biphenyl-4-yl)amino]phenylboronic acid, 1.8 g (4.5 mmol) of
3-(4-bromophenyl)-9-phenyl-9H-carbazole, 10 mg (0.045 mmol) of
palladium(II) acetate, and 0.69 g (0.23 mmol) of
tri(o-tolyl)phosphine were put, and 10 mL of a potassium carbonate
solution (2.0 mol/L) and 20 mL of ethylene glycol dimethyl ether
(abbreviation: DME) were added thereto. This mixture was deaerated
while being stirred under low pressure, and the atmosphere in the
flask was substituted by nitrogen. This mixture was stirred at
90.degree. C. for 5 hours. After the stirring, toluene was added to
the reaction mixture, and the mixture was heated at 90.degree.
C.
[0351] After the heating, this suspension was separated into an
organic layer and an aqueous layer. After the separation, the
organic layer was washed with a saturated sodium hydrogen carbonate
solution and a saturated saline solution. Magnesium sulfate was
added to the organic layer, and the organic layer was dried.
Suction filtration was performed on this mixture through Celite,
alumina, and then Florisil to obtain filtrate. The obtained
filtrate was concentrated to obtain a solid. The obtained filtrate
was dissolved in toluene and purified by silica gel column
chromatography. The silica gel column chromatography was performed
by using toluene as a developing solvent. A solid which was
obtained by concentrating the obtained fraction was recrystallized
with a mixture solvent of toluene and hexane to obtain 2.4 g of an
objective white solid at a yield of 74%.
[0352] Sublimation purification of the obtained white solid was
performed by a train sublimation method. The sublimation
purification was performed under a reduced pressure of 7.0 Pa, with
a flow rate of argon at 3 mL/min, at 340.degree. C. for 20 hours to
obtain 0.70 g of the white solid, the theoretical yield of which is
1.5 g, at a yield of 46%.
[0353] A compound which was obtained through the above Step 2 was
measured by a nuclear magnetic resonance method (.sup.1H NMR). The
measurement result is described below, and the .sup.1H NMR chart is
shown in FIGS. 46A and 46B. It was found from the measurement
result that the carbazole derivative of the present invention,
PCTBi1BP (abbreviation) represented by the above structural formula
(190), was obtained. .sup.1H NMR (CDCl.sub.3, 300 MHz): .delta.
(ppm)=7.18-7.83 (m, 36H), 8.21 (d, J=7.3 Hz, 1H), 8.40 (s, 1H).
[0354] In addition, an absorption spectrum of PCTBi1BP
(abbreviation) (measurement range: 200 nm to 800 nm) was measured.
In the case of the toluene solution, an absorption peak on a long
wavelength side was observed at around 350 nm, and in the case of
the thin film, an absorption peak on a long wavelength side was
observed at around 357 nm.
[0355] In addition, an emission spectrum of PCTBi1BP (abbreviation)
(measurement range: 370 nm to 550 nm) was measured. In the case of
the toluene solution, a maximum emission wavelength was 410 nm
(excitation wavelength: 320 nm), and in the case of the thin film,
a maximum emission wavelength was 447 nm (excitation wavelength:
340 nm). Since the measurement method of an absorption spectrum and
an emission spectrum is similar to that of Embodiment 1, the
description is omitted.
[0356] The result of measuring the thin film using a photoelectron
spectrometer (AC-2, manufactured by Riken Keiki Co., Ltd.) under
the atmosphere indicated that the HOMO level of PCTBi1BP
(abbreviation) was -5.50 eV. The Tauc plot of the absorption
spectrum of the thin film revealed that the absorption edge was
3.14 eV. Thus, the energy gap in the solid state was estimated to
be 3.14 eV, which means that the LUMO level of PCTBi1BP
(abbreviation) is -2.36 eV.
[0357] An oxidation-reduction reaction characteristic of PCTBi1BP
(abbreviation) was examined by a cyclic voltammetry (CV)
measurement. Since the measurement method is similar to that of
Embodiment 1, the description is omitted.
[0358] According to the calculation similar to that of Embodiment
1, the HOMO level of PCTBi1BP (abbreviation) was found to be=-5.46
[eV]. In addition, the oxidation peak took a similar value even
after the 100 cycles. Accordingly, it was found that repetition of
the oxidation reduction between an oxidation state and a neutral
state had favorable characteristics.
[0359] In addition, the glass transition temperature of PCTBi1BP
(abbreviation) was examined with a differential scanning
calorimetry (Pyris 1 DSC, manufactured by Perkin Elmer Co., Ltd.).
According to the measurement results, it was found that the glass
transition temperature was 133.degree. C. In this manner, PCTBi1BP
(abbreviation) has a high glass transition temperature and
favorable heat resistance. In addition, the crystallization peak
does not exist; thus, it was found that PCTBi1BP (abbreviation) is
a substance which is hard to be crystallized.
[0360] Note that with the efficiency, the drive voltage at a
luminance of about 1000 cd/m.sup.2, and the reliability of a
light-emitting element formed using PCTBi1BP (abbreviation) which
was synthesized in Embodiment 7 in a manner similar to that of
Embodiment 5 for a hole-transporting layer, favorable values
equivalent to those of a light-emitting element 8 which will be
formed using PCBBiNB in Embodiment 10 were obtained. When the drive
voltage of the light-emitting element was 3.6 V, the luminance and
the current value were 873 cd/m.sup.2 and 0.56 mA, respectively,
and the light-emitting element exhibited 80% of the initial
luminance when driven for 110 hours.
Embodiment 8
[0361] In Embodiment 8, a synthetic method of a carbazole
derivative of the present invention,
4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)-triphenylamine
(abbreviation: PCBANB) represented by a structural formula (343),
will be specifically described.
##STR00141##
Step 1: Synthesis of 3-(4-bromophenyl)-9-phenyl-9H-carbazole
[0362] A synthetic scheme of
3-(4-bromophenyl)-9-phenyl-9H-carbazole in Step 1 is shown in the
following (J-1).
##STR00142##
[0363] In a 200-mL three-neck flask, 3.7 g (9.9 mmol) of
3-iodo-9-phenyl-9H-carbazole, 2.0 g (9.9 mmol) of 4-bromo
phenylboronic acid, and 0.61 g (2.0 mmol) of tri(o-tolyl)phosphine
were put, and 50 mL of ethylene glycol dimethyl ether
(abbreviation: DME) and 10 mL of a potassium carbonate solution (2
mol/L) were added to this mixture. This mixture was deaerated while
being stirred under low pressure, and the atmosphere in the flask
was substituted by nitrogen after the deaeration.
[0364] Then, 0.11 g (0.50 mmol) of palladium(II) acetate was added
to this mixture. This mixture was stirred at 80.degree. C. for 9.5
hours. After the stirring, this mixture was cooled to room
temperature and then washed twice with water. The obtained aqueous
layer was extracted twice with toluene. Then, the extracted
solution was combined with an organic layer, followed by washing
with a saturated saline solution. The organic layer was dried with
magnesium sulfate, this mixture was naturally filtrated, and then
the filtrate was concentrated.
[0365] The obtained oily substance was dissolved in about 20 mL of
toluene, and suction filtration was performed on this solution
through Celite, alumina, and then Florisil. A solid which was
obtained by concentrating the obtained filtrate was purified by
silica gel column chromatography (developing solvent,
toluene:hexane=1:4) to obtain 1.9 g of an objective white
powder-like solid at a yield of 49%.
Step 2: Synthesis of 4-(1-naphthyl)diphenylamine
[0366] A synthetic scheme of 4-(1-naphthyl)diphenylamine in Step 2
is shown in the following (J-2).
##STR00143##
[0367] In a 200-mL three-neck flask, 12 g (50 mmol) of
4-bromodiphenylamine, 8.6 g (50 mmol) of 1-naphthaleneboronic acid,
22 mg (0.1 mmol) of palladium(II) acetate, and 60 mg (0.2 mmol) of
tri(o-tolyl)phosphine were put, and 50 mL of toluene, 20 mL of
ethanol, and 35 mL of a potassium carbonate solution (2 mol/L) were
added to this mixture. This mixture was deaerated while being
stirred under low pressure. After the deaeration, the mixture was
stirred under a nitrogen atmosphere at 90.degree. C. for 2 hours to
be reacted.
[0368] After the reaction, 100 mL of toluene was added to this
reaction mixture, and this suspension was filtrated through
Florisil and then Celite. The obtained filtrate was washed with
water. Then, magnesium sulfate was added to remove moisture. This
suspension was concentrated and purified by silica gel column
chromatography (developing solvent, toluene:hexane:ethyl
acetate=1:8:1). The obtained fraction was concentrated, and
methanol was added thereto. The mixture was irradiated with
supersonic and then recrystallized to obtain 3.0 g of an objective
white powder at a yield of 20%.
Step 3: Synthesis of
4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)-triphenylamine
(Abbreviation: PCBANB)
[0369] A synthetic scheme of
4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)-triphenylamine in
Step 3 is shown in the following (J-3).
##STR00144##
[0370] In a 50-mL three-neck flask, 1.2 g (3.0 mmol) of
3-(4-bromophenyl)-9-phenyl-9H-carbazole, 0.9 g (3.0 mmol) of
4-(1-naphthyl)diphenylamine, 0.5 g (5.0 mmol) of sodium
tert-butoxide, and 6.0 mg (0.01 mmol) of
bis(dibenzylideneacetone)palladium(0) were put, and 15 mL of
dehydrated xylene was added to this mixture. This mixture was
deaerated while being stirred under low pressure. After the
deaeration, 0.06 mL (0.03 mmol) of tri(tert-butyl)phosphine (10 wt
% hexane solution) was added thereto. This mixture was stirred
under a nitrogen atmosphere at 120.degree. C. for 4.5 hours to be
reacted.
[0371] After the reaction, 250 mL of toluene was added to this
reaction mixture, and this suspension was filtrated through
Florisil, silica gel, alumina, and then Celite. The obtained
filtrate was washed with water. Then, magnesium sulfate was added
to remove moisture. This suspension was filtrated through Florisil,
alumina, silica gel, and then Celite to obtain filtrate. The
obtained filtrate was concentrated, and acetone and methanol were
added thereto. The mixture was irradiated with supersonic and then
recrystallized to obtain 1.5 g of an objective white powder at a
yield of 82%.
[0372] An Rf value of the objective substance by a silica gel thin
layer chromatography (TLC) (developing solvent, ethyl
acetate:hexane 1:10) was 0.34, that of
3-(4-bromophenyl)-9-phenyl-9H-carbazole was 0.46, and that of
4-(1-naphthyl)diphenylamine was 0.25.
[0373] A compound which was obtained through the above Step 3 was
measured by a nuclear magnetic resonance method (.sup.1H NMR). The
measurement result is described below, and the .sup.1H NMR chart is
shown in FIGS. 47A and 47B. It was found from the measurement
result that the carbazole derivative of the present invention,
PCBANB (abbreviation) represented by the above structural formula
(343), was obtained. .sup.1H NMR (CDCl.sub.3, 300 MHz): .delta.
(ppm)=7.07 (t, J=6.6 Hz, 1H), 7.25-7.67 (m, 26H), 7.84 (d, J=7.8
Hz, 1H), 7.89-7.92 (m, 1H), 8.03-8.07 (m, 1H), 8.18 (d, J=7.8 Hz,
1H), 8.35 (d, J=0.9 Hz, 1H).
[0374] In addition, an absorption spectrum of PCBANB (abbreviation)
(measurement range: 200 nm to 800 nm) was measured. In the case of
the toluene solution, an absorption peak on a long wavelength side
was observed at around 335 nm, and in the case of the thin film, an
absorption peak on a long wavelength side was observed at around
341 nm.
[0375] In addition, an emission spectrum of PCBANB (abbreviation)
(measurement range: 370 nm to 550 nm) was measured. In the case of
the toluene solution, a maximum emission wavelength was 410 nm
(excitation wavelength: 345 nm), and in the case of the thin film,
a maximum emission wavelength was 433 nm (excitation wavelength:
341 nm).
[0376] Since the measurement method of an absorption spectrum and
an emission spectrum is similar to that of Embodiment 1, the
description is omitted.
[0377] The result of measuring the thin film using a photoelectron
spectrometer (AC-2, manufactured by Riken Keiki Co., Ltd.) under
the atmosphere indicated that the HOMO level of PCBANB
(abbreviation) was -5.44 eV. The Tauc plot of the absorption
spectrum of the thin film revealed that the absorption edge was
3.25 eV. Thus, the energy gap in the solid state was estimated to
be 3.25 eV, which means that the LUMO level of PCBANB
(abbreviation) is -2.19 eV.
[0378] An oxidation-reduction reaction characteristic of PCBANB
(abbreviation) was examined by a cyclic voltammetry (CV)
measurement. Since the measurement method is similar to that of
Embodiment 1, the description is omitted.
[0379] According to the calculation similar to that of Embodiment
1, the HOMO level of PCBANB (abbreviation) was found to be=-5.44
[eV]. In addition, the oxidation peak took a similar value even
after the 100 cycles. Accordingly, it was found that repetition of
the oxidation reduction between an oxidation state and a neutral
state had favorable characteristics.
[0380] In addition, the glass transition temperature of PCBANB
(abbreviation) was examined with a differential scanning
calorimetry (Pyris 1 DSC, manufactured by Perkin Elmer Co., Ltd.).
According to the measurement results, it was found that the glass
transition temperature was 115.degree. C. In this manner, PCBANB
(abbreviation) has a high glass transition temperature and
favorable heat resistance. In addition, the crystallization peak
does not exist; thus, it was found that PCBANB (abbreviation) is a
substance which is hard to be crystallized.
[0381] In addition, FIGS. 56 to 59 show the measurement results in
element characteristics of the light-emitting element 6 which was
formed using, for a hole-transporting layer, PCBANB (abbreviation)
which is the carbazole derivative of the present invention that was
synthesized in Embodiment 8 in a manner similar to that of
Embodiment 5. It was found that the hole-transporting material of
the present invention which was used for the light-emitting element
6 showed higher luminance, even when the hole-transporting material
of the present invention which was used for the light-emitting
element 6 was compared to NPB of the light-emitting element 1. Note
that the light-emitting element 1 which is a comparative
light-emitting element was formed using
4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB)
for the hole-transporting layer 151 in a manner similar to that of
Embodiment 5.
[0382] In addition, in the light-emitting element 6, an emission
wavelength derived from PCBAPA which is a blue light-emitting
material was observed but an emission wavelength derived from the
hole-transporting material was not observed from emission spectrum
shown in FIG. 59. Thus, it was found that the hole-transporting
material of the present invention realizes favorable carrier
balance in the structure of the light-emitting element 6.
[0383] FIG. 60 shows the result of a continuous lighting test in
which the light-emitting element 6 was continuously lit by constant
current driving with the initial luminance set at 1000 cd/m.sup.2
(the vertical axis indicates the relative luminance on the
assumption that 1000 cd/m.sup.2 is 100%). From the results in FIG.
60, the light-emitting element 6 was found to have a longer
lifetime, as compared to the light-emitting element 1. Thus, a long
lifetime light-emitting element can be obtained by applying the
present invention.
Embodiment 9
[0384] In Embodiment 9, a synthetic method of a carbazole
derivative of the present invention,
4,4'-di(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)-triphenylamine
(abbreviation: PCBNBB) represented by a structural formula (229),
will be specifically described.
##STR00145##
Step 1: Synthesis of 4,4'-dibromotriphenylamine
[0385] A synthetic scheme of 4,4'-dibromotriphenylamine in Step 1
is shown in the following (K-1).
##STR00146##
[0386] After 12 g (50 mmol) of triphenylamine was dissolved in a
mixture solvent of 250 mL of ethyl acetate in a 500-mL conical
flask, 18 g (100 mmol) of N-bromo succinimide (abbreviation: NBS)
was added to this solution. After that, this mixture was stirred at
room temperature for 24 hours. After completion of the reaction,
this mixture solution was washed with water, and magnesium sulfate
was added thereto to remove moisture. This mixture solution was
filtrated and the obtained filtrate was concentrated and dried to
obtain 20 g of an objective white solid at a yield of 99%.
Step 2: Synthesis of 4,4'-di(1-naphthyl)triphenylamine
[0387] A synthetic scheme of 4,4'-di(1-naphthyl)triphenylamine in
Step 2 is shown in the following (K-2).
##STR00147##
[0388] In a 100-mL three-neck flask, 6.0 g (15 mmol) of
4,4'-dibromotriphenylamine, 5.2 g (30 mmol) of 1-naphthaleneboronic
acid, 2.0 mg (0.01 mmol) of palladium(II) acetate, and 6.0 mg (0.02
mmol) of tri(o-tolyl)phosphine were put, and 20 mL of toluene, 5 mL
of ethanol, and 20 mL of a potassium carbonate solution (2 mol/L)
were added to this mixture. This mixture was deaerated while being
stirred under low pressure. After the deaeration, the mixture was
stirred under a nitrogen atmosphere at 90.degree. C. for 4.5 hours
to be reacted.
[0389] After the reaction, 150 mL of toluene was added to this
reaction mixture, and on this suspension was filtrated through
Florisil and then Celite. The obtained filtrate was washed with
water. Then, magnesium sulfate was added to remove moisture. This
suspension was filtrated through Florisil, alumina, silica gel, and
then Celite to obtain filtrate. The obtained filtrate was
concentrated, and methanol was added thereto. The mixture was
irradiated with supersonic and then recrystallized to obtain 6.4 g
of an objective white powder at a yield of 86%.
[0390] An Rf value of the objective substance by a silica gel thin
layer chromatography (TLC) (developing solvent, ethyl
acetate:hexane=1:10) was 0.53 and that of
4,4'-dibromotriphenylamine was 0.69.
Step 3: Synthesis of
4-bromo-4',4''-di(1-naphthyl)triphenylamine
[0391] A synthetic scheme of
4-bromo-4',4''-di(1-naphthyl)triphenylamine in Step 3 is shown in
the following (K-3).
##STR00148##
[0392] After 6.4 g (13 mmol) of 4,4'-di(1-naphthyl)triphenylamine
was dissolved in 150 mL of ethyl acetate in a 300-mL conical flask,
2.3 g (13 mmol) of N-bromo succinimide (abbreviation: NBS) was
added to this solution. After that, this mixture was stirred at
room temperature for 24 hours. After completion of the reaction,
this mixture solution was washed with water, and magnesium sulfate
was added thereto to remove moisture. This mixture solution was
filtrated, the obtained filtrate was concentrated, and methanol was
added thereto. The mixture was irradiated with supersonic and then
recrystallized to be purified by silica gel column chromatography
(developing solvent, toluene:hexane=1:5). Accordingly, 1.6 g of an
objective white powder was obtained at a yield of 22%.
Step 4: Synthesis of
4,4'-di(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)-triphenylamine
(Abbreviation: PCBNBB)
[0393] A synthetic scheme of
4,4'-di(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)-triphenylamine
in Step 4 is shown in the following (K-4).
##STR00149##
[0394] In a 50-mL three-neck flask, 1.4 g (2.5 mmol) of
4-bromo-4',4''-di(1-naphthyl)triphenylamine, 0.7 g (2.5 mmol) of
9-phenyl-9H-carbazol-3-yl-boronic acid, 4.0 mg (0.02 mmol) of
palladium(II) acetate, and 6.0 mg (0.02 mmol) of
tri(o-tolyl)phosphine were put, and 20 mL of toluene, 5 mL of
ethanol, and 2.5 mL of a potassium carbonate solution (2 mol/L)
were added to this mixture. This mixture was deaerated while being
stirred under low pressure. After the deaeration, the mixture was
stirred under a nitrogen atmosphere at 90.degree. C. for 6.5 hours
to be reacted.
[0395] After the reaction, 150 mL of toluene was added to this
reaction mixture, and this suspension was filtrated through
Florisil and then Celite. The obtained filtrate was washed with
water. Then, magnesium sulfate was added to remove moisture. This
suspension was filtrated through Florisil, alumina, silica gel, and
then Celite to obtain filtrate. The obtained filtrate was
concentrated and purified by silica gel column chromatography
(developing solvent, toluene:hexane=1:4). The obtained fraction was
concentrated, and methanol was added thereto. The mixture was
irradiated with supersonic and then recrystallized to obtain 0.4 g
of an objective white powder at a yield of 22%.
[0396] A compound which was obtained through the above Step 4 was
measured by a nuclear magnetic resonance method (.sup.1H NMR). The
measurement result is described below, and the .sup.1H NMR chart is
shown in FIGS. 48A and 48B. It was found from the measurement
result that the carbazole derivative of the present invention,
PCBNBB (abbreviation) represented by the above structural formula
(229), was obtained. .sup.1H NMR (CDCl.sub.3, 300 MHz): .delta.
(ppm)=7.28-7.72 (m, 30H), 7.85 (d, J=7.8 Hz, 2H), 7.90-7.93 (m,
2H), 8.06-8.09 (m, 2H), 8.19 (d, J=7.5 Hz, 1H), 8.38 (d, J=1.5 Hz,
1H).
[0397] In addition, an absorption spectrum of PCBNBB (abbreviation)
(measurement range: 200 nm to 800 nm) was measured. In the case of
the toluene solution, an absorption peak on a long wavelength side
was observed at around 345 nm, and in the case of the thin film, an
absorption peak on a long wavelength side was observed at around
355 nm.
[0398] In addition, an emission spectrum of PCBNBB (abbreviation)
(measurement range: 370 nm to 550 nm) was measured. In the case of
the toluene solution, a maximum emission wavelength was 413 nm
(excitation wavelength: 355 nm), and in the case of the thin film,
a maximum emission wavelength was 428 nm (excitation wavelength:
370 nm).
[0399] Since the measurement method of an absorption spectrum and
an emission spectrum is similar to that of Embodiment 1, the
description is omitted.
[0400] The result of measuring the thin film using a photoelectron
spectrometer (AC-2, manufactured by Riken Keiki Co., Ltd.) under
the atmosphere indicated that the HOMO level of PCBNBB
(abbreviation) was -5.46 eV. The Tauc plot of the absorption
spectrum of the thin film revealed that the absorption edge was
3.15 eV. Thus, the energy gap in the solid state was estimated to
be 3.15 eV, which means that the LUMO level of PCBNBB
(abbreviation) is -2.31 eV.
[0401] An oxidation-reduction reaction characteristic of PCBNBB
(abbreviation) was examined by a cyclic voltammetry (CV)
measurement. Since the measurement method is similar to that of
Embodiment 1, the description is omitted. According to the
calculation similar to that of Embodiment 1, the HOMO level of
PCBNBB (abbreviation) was found to be=-5.43 [eV]. In addition, the
oxidation peak took a similar value even after the 100 cycles.
Accordingly, it was found that repetition of the oxidation
reduction between an oxidation state and a neutral state had
favorable characteristics.
[0402] In addition, the glass transition temperature of PCBNBB
(abbreviation) was examined with a differential scanning
calorimetry (Pyris 1 DSC, manufactured by Perkin Elmer Co., Ltd.).
According to the measurement results, it was found that the glass
transition temperature was 136.degree. C. In this manner, PCBNBB
(abbreviation) has a high glass transition temperature and
favorable heat resistance. In addition, the crystallization peak
does not exist; thus, it was found that PCBNBB (abbreviation) is a
substance which is hard to be crystallized.
[0403] In addition, FIGS. 56 to 59 show the measurement results in
element characteristics of the light-emitting element 7 which was
formed using, for a hole-transporting layer, PCBNBB (abbreviation)
which is the carbazole derivative of the present invention that was
synthesized in Embodiment 9 in a manner similar to that of
Embodiment 5. It was found that the hole-transporting material of
the present invention which was used for the light-emitting element
7 showed higher luminance, even when the hole-transporting material
of the present invention which was used for the light-emitting
element 7 was compared to NPB of the light-emitting element 1. Note
that the light-emitting element 1 which is a comparative
light-emitting element was formed using
4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB)
for the hole-transporting layer 151 in a manner similar to that of
Embodiment 5.
[0404] In addition, in the light-emitting element 7, an emission
wavelength derived from PCBAPA which is a blue light-emitting
material was observed but an emission wavelength derived from the
hole-transporting material was not observed from emission spectrum
shown in FIG. 59. Thus, it was found that the hole-transporting
material of the present invention realizes favorable carrier
balance in the structure of the light-emitting element 7.
[0405] FIG. 60 shows the result of a continuous lighting test in
which the light-emitting element 7 was continuously lit by constant
current driving with the initial luminance set at 1000 cd/m.sup.2
(the vertical axis indicates the relative luminance on the
assumption that 1000 cd/m.sup.2 is 100%). From the results in FIG.
60, the light-emitting element 7 was found to have a longer
lifetime, as compared to the light-emitting element 1.
Embodiment 10
[0406] In Embodiment 10, a synthetic method of a carbazole
derivative of the present invention,
4-(1-naphthyl)-4'-phenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine
(abbreviation: PCBBiNB) represented by a structural formula (220),
will be specifically described.
##STR00150##
Step 1: Synthesis of 4-phenyltriphenylamine
[0407] A synthetic scheme of 4-phenyltriphenylamine in Step 1 is
shown in the following (L-1).
##STR00151##
[0408] In a 300-mL three-neck flask, 9.3 g (40 mmol) of
4-bromophenyl, 6.8 g (40 mmol) of diphenylamine, 5.0 g (50 mol) of
sodium tert-butoxide, and 10 mg of
bis(dibenzylideneacetone)palladium(0) were put, and the atmosphere
in the flask was substituted by nitrogen. Then, 100 mL of xylene
and 0.6 mL of tri(tert-butyl)phosphine (10 wt % hexane solution)
were added to this mixture.
[0409] This mixture was deaerated while being stirred under low
pressure. After the atmosphere was substituted by nitrogen, the
mixture was stirred at 130.degree. C. for 3.5 hours. After the
stirring, 250 mL of toluene was added to the reaction mixture, and
this suspension was filtrated through Celite, alumina, and then
Florisil. The obtained filtrate was washed with water and dried,
and magnesium sulfate was added thereto. This mixture was filtrated
through Celite, alumina, and then Florisil to obtain filtrate. The
obtained filtrate was concentrated, and methanol was added thereto.
The mixture was irradiated with supersonic and then recrystallized
to obtain 11 g of an objective white powder at a yield of 89%.
Step 2: Synthesis of 4-bromo-4'-phenyltriphenylamine
[0410] A synthetic scheme of 4-bromo-4'-phenyltriphenylamine in
Step 2 is shown in the following (L-2).
##STR00152##
[0411] In a 500-mL conical flask, 6.4 g (20 mmol) of
4-phenyltriphenylamine, 250 mL of ethyl acetate, and 150 mL of
toluene were added and the mixture was stirred, and then 3.6 g (20
mmol) of N-bromo succinimide (abbreviation: NBS) was added to this
solution. After that, this mixture was stirred for 27.5 hours.
After the obtained suspension was washed with water, moisture was
removed by magnesium sulfate. This suspension was concentrated and
dried to obtain 7.7 g of an objective white powder at a yield of
96%.
Step 3: Synthesis of 4-(1-naphthyl)-4'-phenyltriphenylamine
[0412] A synthetic scheme of 4-(1-naphthyl)-4'-phenyltriphenylamine
in Step 3 is shown in the following (L-3).
##STR00153##
[0413] In a 100-mL three-neck flask, 8.0 g (20 mmol) of
4-bromo-4'-phenyltriphenylamine, 3.4 g (20 mmol) of
1-naphthaleneboronic acid, 44 mg (0.2 mmol) of palladium(II)
acetate, and 60 mg (0.4 mmol) of tri(o-tolyl)phosphine were put,
and 20 mL of toluene, 10 mL of ethanol, and 15 mL of a potassium
carbonate solution (2 mol/L) were added to this mixture. This
mixture was deaerated while being stirred under low pressure. After
the deaeration, the mixture was stirred under a nitrogen atmosphere
at 90.degree. C. for 6.5 hours to be reacted.
[0414] After the reaction, 150 mL of toluene was added to this
reaction mixture, and this suspension was filtrated through
Florisil, silica gel, and then Celite. The obtained filtrate was
washed with water. Then, magnesium sulfate was added to remove
moisture. This suspension was filtrated through Florisil, alumina,
silica gel, and then Celite to obtain filtrate. The obtained
filtrate was concentrated, and methanol was added thereto. The
mixture was irradiated with supersonic and then recrystallized to
obtain 8.6 g of an objective white powder at a yield of 97%.
[0415] An Rf value of the objective substance by a silica gel thin
layer chromatography (TLC) (developing solvent, ethyl
acetate:hexane=1:10) was 0.43 and that of
4-bromo-4'-phenyltriphenylamine was 0.50.
Step 4: Synthesis of
4-bromo-4'-(1-naphthyl)-4''-phenyl-triphenylamine
[0416] A synthetic scheme of
4-bromo-4'-(1-naphthyl)-4''-phenyl-triphenylamine in Step 4 is
shown in the following (L-4).
##STR00154##
[0417] After 8.6 g (19 mmol) of
4-(1-naphthyl)-4'-phenyltriphenylamine was dissolved in 150 mL of
ethyl acetate in a 300-mL conical flask, 3.4 g (19 mmol) of N-bromo
succinimide (abbreviation: NBS) was added to this solution. After
that, this mixture was stirred at room temperature for 24 hours.
After completion of the reaction, this mixture solution was washed
with water, and magnesium sulfate was added thereto to remove
moisture. This mixture solution was filtrated. The obtained
filtrate was concentrated and purified by silica gel column
chromatography (developing solvent, toluene:hexane=1:4). The
obtained fraction was concentrated, and methanol was added thereto.
The mixture was irradiated with supersonic and then recrystallized
to obtain 8.1 g of an objective white powder at a yield of 80%.
Step 5: Synthesis of
4-(1-naphthyl)-4'-phenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine
(Abbreviation: PCBBiNB)
[0418] A synthetic scheme of
4-(1-naphthyl)-4'-phenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine
in Step 5 is shown in the following (L-5).
##STR00155##
[0419] In a 50-mL three-neck flask, 1.6 g (3.0 mmol) of
4-bromo-4'-(1-naphthyl)-4''-phenyl-triphenylamine, 0.9 g (30 mmol)
of 9-phenyl-9H-carbazol-3-yl-boronic acid, 12 mg (0.06 mmol) of
palladium(II) acetate, and 36 mg (0.12 mmol) of
tri(o-tolyl)phosphine were put, and 15 mL of toluene, 15 mL of
ethanol, and 3 mL of a potassium carbonate solution (2 mol/L) were
added to this mixture. This mixture was deaerated while being
stirred under low pressure. After the deaeration, the mixture was
stirred under a nitrogen atmosphere at 90.degree. C. for 2 hours to
be reacted.
[0420] After the reaction, 150 mL of toluene was added to this
reaction mixture, and this suspension was filtrated through
Florisil, silica gel, and then Celite. The obtained filtrate was
washed with water. Then, magnesium sulfate was added to remove
moisture. This suspension was filtrated through Florisil, alumina,
silica gel, and then Celite to obtain filtrate. The obtained
filtrate was concentrated and purified by silica gel column
chromatography (developing solvent, toluene:hexane=1:4). The
obtained fraction was concentrated, acetone and methanol were added
thereto. The mixture was irradiated with supersonic and then
recrystallized to obtain 0.9 g of an objective white powder at a
yield of 44%.
[0421] An Rf value of the objective substance by a silica gel thin
layer chromatography (TLC) (developing solvent, ethyl
acetate:hexane=1:10) was 0.26 and that of
4-bromo-4'-(1-naphthyl)-4''-phenyl-triphenylamine was 0.45.
[0422] A compound which was obtained through the above Step 5 was
measured by a nuclear magnetic resonance method (.sup.1H NMR). The
measurement result is described below, and the .sup.1H NMR chart is
shown in FIGS. 49A and 49B. It was found from the measurement
result that the carbazole derivative of the present invention,
PCBBiNB (abbreviation) represented by the above structural formula
(220), was obtained. .sup.1H NMR (CDCl.sub.3, 300 MHz): .delta.
(ppm)=7.27-7.69 (m, 31H), 7.84 (d, J=7.8 Hz, 1H), 7.89-7.92 (m,
1H), 8.04-8.08 (m, 1H), 8.18 (d, J=7.8 Hz, 1H), 8.36 (d, J=1.5 Hz,
1H).
[0423] In addition, an absorption spectrum of PCBBiNB
(abbreviation) (measurement range: 200 nm to 800 nm) was measured.
In the case of the toluene solution, an absorption peak on a long
wavelength side was observed at around 342 nm, and in the case of
the thin film, an absorption peak on a long wavelength side was
observed at around 351 nm.
[0424] In addition, an emission spectrum of PCBBiNB (abbreviation)
(measurement range: 370 nm to 550 nm) was measured. In the case of
the toluene solution, a maximum emission wavelength was 409 nm
(excitation wavelength: 355 nm), and in the case of the thin film,
a maximum emission wavelength was 433 nm (excitation wavelength:
336 nm).
[0425] Since the measurement method of an absorption spectrum and
an emission spectrum is similar to that of Embodiment 1, the
description is omitted.
[0426] The result of measuring the thin film using a photoelectron
spectrometer (AC-2, manufactured by Riken Keiki Co., Ltd.) under
the atmosphere indicated that the HOMO level of PCBBiNB
(abbreviation) was -5.35 eV. The Tauc plot of the absorption
spectrum of the thin film revealed that the absorption edge was
3.18 eV Thus, the energy gap in the solid state was estimated to be
3.18 eV, which means that the LUMO level of PCBBiNB (abbreviation)
is -2.17 eV.
[0427] An oxidation-reduction reaction characteristic of PCBBiNB
(abbreviation) was examined by a cyclic voltammetry (CV)
measurement. Since the measurement method is similar to that of
Embodiment 1, the description is omitted.
[0428] According to the calculation similar to that of Embodiment
1, the HOMO level of PCBBiNB (abbreviation) was found to be=-5.42
[eV]. In addition, the oxidation peak took a similar value even
after the 100 cycles. Accordingly, it was found that repetition of
the oxidation reduction between an oxidation state and a neutral
state had favorable characteristics.
[0429] In addition, the glass transition temperature of PCBBiNB
(abbreviation) was examined with a differential scanning
calorimetry (Pyris 1 DSC, manufactured by Perkin Elmer Co., Ltd.).
According to the measurement results, it was found that the glass
transition temperature was 143.degree. C. In this manner, PCBBiNB
(abbreviation) has a high glass transition temperature and
favorable heat resistance. In addition, the crystallization peak
does not exist; thus, it was found that PCBBiNB (abbreviation) is a
substance which is hard to be crystallized.
[0430] In addition, FIGS. 56 to 59 show the measurement results in
element characteristics of the light-emitting element 8 which was
formed using, for a hole-transporting layer, PCBBiNB (abbreviation)
which is the carbazole derivative of the present invention that was
synthesized in Embodiment 10 in a manner similar to that of
Embodiment 5. It was found that the hole-transporting material of
the present invention which was used for the light-emitting element
8 showed higher luminance, even when the hole-transporting material
of the present invention which was used for the light-emitting
element 8 was compared to NPB of the light-emitting element 1. Note
that the light-emitting element 1 which is a comparative
light-emitting element was formed using
4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB)
for the hole-transporting layer 151 in a manner similar to that of
Embodiment 5.
[0431] In addition, in the light-emitting element 8, an emission
wavelength derived from PCBAPA which is a blue light-emitting
material was observed but an emission wavelength derived from the
hole-transporting material was not observed from emission spectrum
shown in FIG. 59. Thus, it was found that the hole-transporting
material of the present invention realizes favorable carrier
balance in the structure of the light-emitting element 8.
[0432] FIG. 60 shows the result of a continuous lighting test in
which the light-emitting element 8 was continuously lit by constant
current driving with the initial luminance set at 1000 cd/m.sup.2
(the vertical axis indicates the relative luminance on the
assumption that 1000 cd/m.sup.2 is 100%). From the results in FIG.
60, the light-emitting element 8 was found to have a longer
lifetime, as compared to the light-emitting element 1. Thus, a long
lifetime light-emitting element can be obtained by applying the
present invention.
[0433] In addition, as another structure of the light-emitting
element 8 shown in Embodiment 10, PCBBiNB (abbreviation) was used
instead of NPB (abbreviation), which was used at the time of
forming the first layer 1511, and was co-evaporated with
molybdenum(VI) oxide to form the first layer 1511. With the
efficiency, the drive voltage at a luminance of about 1000
cd/m.sup.2, and the reliability of such a light-emitting element 8,
favorable values equivalent to those of the light-emitting element
8 were obtained. The light-emitting element 8 was formed in
Embodiment 10 by using a co-evaporation film of NPB and
molybdenum(VI) oxide for a hole-injecting layer and using PCBBiNB
(abbreviation) for a hole-transporting layer. When the drive
voltage of the light-emitting element 8 was 4.2 V, the luminance
and the current value were 1062 cd/m.sup.2 and 0.75 mA,
respectively, and the light-emitting element 8 exhibited 81% of the
initial luminance when driven for 350 hours.
[0434] As thus described, it was found that PCBBiNB (abbreviation)
was a favorable material which can be used for both the first layer
1511 which is a hole-injecting layer and the second layer 1512
which is a hole-transporting layer at the same time. Accordingly,
an element could be manufactured easily and material use efficiency
could also be improved.
Embodiment 11
[0435] In Embodiment 11, a synthetic method of a carbazole
derivative of the present invention, [0436]
[4'-(1-naphthyl)biphenyl-4-yl](phenyl)[4-(9-phenyl-9H-carbazol-3-yl)pheny-
l]amine (abbreviation: PCBANT) represented by a structural formula
(355), will be specifically described.
##STR00156##
[0436] Step 1: Synthesis of
4-(4-bromophenyl)-4'-phenyl-triphenylamine
[0437] A synthetic scheme of
4-(4-bromophenyl)-4'-phenyl-triphenylamine in Step 1 is shown in
the following (M-1).
##STR00157##
[0438] In a 500-mL three-neck flask, 22 g (70 mmol) of
4,4'-dibromobiphenyl, 8.5 g (50 mmol) of diphenylamine, 1.9 g (10
mmol) of copper(I) iodide, 2.6 g (10 mmol) of 18-crown-6-ether, 6.9
g (50 mmol) of potassium carbonate, and 50 mL of
1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)pyrimidinone (abbreviation:
DMPU) were put, and the mixture was stirred under a nitrogen
atmosphere at 180.degree. C. for 37 hours.
[0439] After the reaction, 500 mL of toluene was added to this
reaction mixture, and this suspension was filtrated through
Florisil, silica gel, and then Celite. The obtained filtrate was
washed with water. Then, magnesium sulfate was added to remove
moisture. This suspension was filtrated through Florisil, alumina,
silica gel, and then Celite to obtain filtrate. The obtained
filtrate was concentrated and purified by silica gel column
chromatography (developing solvent, toluene:hexane=1:4). The
obtained fraction was concentrated, and hexane and methanol were
added thereto. The mixture was irradiated with supersonic and then
recrystallized to obtain 5.3 g of an objective white powder at a
yield of 27%.
[0440] An Rf value of the objective substance by a silica gel thin
layer chromatography (TLC) (developing solvent, ethyl
acetate:hexane=1:10) was 0.5 and that of 4,4'-dibromobiphenyl was
0.59.
Step 2: Synthesis of
[4'-(1-naphthyl)biphenyl-4-yl]diphenylamine
[0441] A synthetic scheme of
[4'-(1-naphthyl)biphenyl-4-yl]diphenylamine in Step 2 is shown in
the following (M-2).
##STR00158##
[0442] In a 100-mL three-neck flask, 4.0 g (10 mmol) of
4-(4-bromophenyl)-4'-phenyl-triphenylamine, 1.7 g (10 mmol) of
1-naphthaleneboronic acid, 11 mg (0.05 mmol) of palladium(II)
acetate, and 15 mg (0.05 mmol) of tri(o-tolyl)phosphine were put,
and 20 mL of toluene, 5 mL of ethanol, and 10 mL of a potassium
carbonate solution (2 mol/L) were added to this mixture. This
mixture was deaerated while being stirred under low pressure. After
the deaeration, the mixture was stirred under a nitrogen atmosphere
at 90.degree. C. for 7 hours to be reacted.
[0443] After the reaction, 150 mL of toluene was added to this
reaction mixture, and this suspension was filtrated through silica
gel, alumina, and then Celite. The obtained filtrate was washed
with water. Then, magnesium sulfate was added to remove moisture.
This suspension was filtrated through silica gel, alumina, and then
Celite to obtain filtrate. The obtained filtrate was concentrated,
and methanol was added thereto. The mixture was irradiated with
supersonic and then recrystallized to obtain 3.6 g of an objective
white powder at a yield of 80%.
[0444] An Rf value of the objective substance by a silica gel thin
layer chromatography (TLC) (developing solvent, ethyl
acetate:hexane=1:10) was 0.58 and that of
4-bromophenyl-4'-phenyl-triphenylamine was 0.65.
Step 3: Synthesis of
(4-bromophenyl)[4'-(1-naphthyl)biphenyl-4-yl]phenylamine
[0445] A synthetic scheme of
(4-bromophenyl)[4'-(1-naphthyl)biphenyl-4-yl]phenylamine in Step 3
is shown in the following (M-3).
##STR00159##
[0446] After 3.6 g (8.0 mmol) of
[4'-(1-naphthyl)biphenyl-4-yl]diphenylamine was dissolved in 100 mL
of ethyl acetate in a 200-mL conical flask, 1.4 g (8.0 mmol) of
N-bromo succinimide (abbreviation: NBS) was added to this solution.
After that, this mixture was stirred at room temperature for 72
hours. After completion of the reaction, this mixture solution was
washed with water, and magnesium sulfate was added thereto to
remove moisture. This mixture solution was filtrated, the obtained
filtrate was concentrated, and methanol was added thereto. The
mixture was irradiated with supersonic and then recrystallized to
obtain 3.9 g of an objective white powder at a yield of 93%.
Step 4: Synthesis of
[4'-(1-naphthyl)biphenyl-4-yl](phenyl)[4-(9-phenyl-9H-carbazol-3-yl)pheny-
l]amine (Abbreviation: PCBANT)
[0447] A synthetic scheme of
[4'-(1-naphthyl)biphenyl-4-yl](phenyl)[4-(9-phenyl-9H-carbazol-3-yl)pheny-
l]amine in Step 4 is shown in the following (M-4).
##STR00160##
[0448] In a 100-mL three-neck flask, 1.6 g (3 mmol) of
(4-bromophenyl)[4'-(1-naphthyl)biphenyl-4-yl]phenylamine, 0.8 g (3
mmol) of 9-phenyl-9H-carbazol-3-boronic acid, 6.0 mg (0.03 mmol) of
palladium(II) acetate, and 18 mg (0.03 mmol) of
tri(o-tolyl)phosphine were put, and 20 mL of toluene, 5 mL of
ethanol, and 3 mL of a potassium carbonate solution (2 mol/L) were
added to this mixture. This mixture was deaerated while being
stirred under low pressure. After the deaeration, the mixture was
stirred under a nitrogen atmosphere at 80.degree. C. for 6.5 hours
to be reacted.
[0449] After the reaction, 150 mL of toluene was added to this
reaction mixture, and this suspension was filtrated through
Florisil, silica gel, and then Celite. The obtained filtrate was
washed with water. Then, magnesium sulfate was added to remove
moisture. This suspension was filtrated through Florisil, alumina,
and then Celite to obtain filtrate. The obtained filtrate was
concentrated and purified by silica gel column chromatography
(developing solvent, toluene:hexane=1:4). The obtained fraction was
concentrated, and methanol was added thereto. The mixture was
irradiated with supersonic and then recrystallized to obtain 1.2 g
of an objective white powder at a yield of 60%.
[0450] An Rf value of the objective substance by a silica gel thin
layer chromatography (TLC) (developing solvent, ethyl
acetate:hexane=1:10) was 0.28 and that of
(4-bromophenyl)[4'-(1-naphthyl)biphenyl-4-yl]phenylamine was
0.42.
[0451] A compound which was obtained through the above Step 4 was
measured by a nuclear magnetic resonance method (.sup.1H NMR). The
measurement result is described below, and the .sup.1H NMR chart is
shown in FIGS. 50A and 50B. It was found from the measurement
result that the carbazole derivative of the present invention,
PCBANT (abbreviation) represented by the above structural formula
(355), was obtained. .sup.1H NMR (CDCl.sub.3, 300 MHz): .delta.
(ppm)=7.08 (t, J=7.5 Hz, 1H), 7.20-7.73 (m, 30H), 7.87 (d, J=8.1
Hz, 1H), 7.92 (d, J=7.2 Hz, 1H), 8.00 (d, J=8.4 Hz, 1H), 8.19 (d,
J=7.8 Hz, 1H), 8.35 (d, J=1.8 Hz, 1H).
[0452] Molecular weight of the above compound was measured by a
TOF-MS detector (Waters Micromass LCT Premier, manufactured by
Waters). A mixture solution containing acetonitrile and 0.1% of a
formic acid solution (mixture rate of acetonitrile and the formic
acid solution, 80/20 vol/vol) was used as a solvent. Accordingly, a
main peak with a molecular weight of 689.30 (mode is ES+) was
detected, and it was confirmed that an objective PCBANT
(abbreviation) was obtained.
[0453] In addition, an absorption spectrum of PCBANT (abbreviation)
(measurement range: 200 nm to 800 nm) was measured. In the case of
the toluene solution, an absorption peak on a long wavelength side
was observed at around 342 nm, and in the case of the thin film, an
absorption peak on a long wavelength side was observed at around
351 nm.
[0454] In addition, an emission spectrum of PCBANT (abbreviation)
(measurement range: 370 nm to 550 nm) was measured. In the case of
the toluene solution, a maximum emission wavelength was 414 nm
(excitation wavelength: 355 nm), and in the case of the thin film,
a maximum emission wavelength was 342 nm (excitation wavelength:
365 nm). Since the measurement method of an absorption spectrum and
an emission spectrum is similar to that of Embodiment 1, the
description is omitted.
[0455] The result of measuring the thin film using a photoelectron
spectrometer (AC-2, manufactured by Riken Keiki Co., Ltd.) under
the atmosphere indicated that the HOMO level of PCBANT
(abbreviation) was -5.38 eV. The Tauc plot of the absorption
spectrum of the thin film revealed that the absorption edge was
3.11 eV. Thus, the energy gap in the solid state was estimated to
be 3.11 eV, which means that the LUMO level of PCBANT
(abbreviation) is -2.27 eV.
[0456] An oxidation-reduction reaction characteristic of PCBANT
(abbreviation) was examined by a cyclic voltammetry (CV)
measurement. Since the measurement method is similar to that of
Embodiment 1, the description is omitted.
[0457] According to the calculation similar to that of Embodiment
1, the HOMO level of PCBANT (abbreviation) was found to be=-5.43
[eV]. In addition, the oxidation peak took a similar value even
after the 100 cycles. Accordingly, it was found that repetition of
the oxidation reduction between an oxidation state and a neutral
state had favorable characteristics.
[0458] In addition, the glass transition temperature of PCBANT
(abbreviation) was examined with a differential scanning
calorimetry (Pyris 1 DSC, manufactured by Perkin Elmer Co., Ltd.).
According to the measurement results, it was found that the glass
transition temperature was 131.degree. C. In this manner, PCBANT
(abbreviation) has a high glass transition temperature and
favorable heat resistance. In addition, the crystallization peak
does not exist; thus, it was found that PCBANT (abbreviation) is a
substance which is hard to be crystallized.
[0459] Note that the efficiency, the drive voltage at a luminance
of about 1000 cd/m.sup.2, and the reliability of a light-emitting
element formed using PCBANT (abbreviation) which was synthesized in
Embodiment 11 in a manner similar to that of Embodiment 5 for a
hole-transporting layer, favorable values equivalent to those of
the light-emitting element 8 which was formed using PCBBiNB in
Embodiment 10 were obtained. When the drive voltage of the
light-emitting element was 4.0 V, the luminance and the current
value were 1186 cd/m.sup.2 and 0.73 mA, respectively, and the
light-emitting element exhibited 65% of the initial luminance when
driven for 180 hours.
Embodiment 12
[0460] In Embodiment 12, a synthetic method of a carbazole
derivative of the present invention,
4-[9-(biphenyl-4-yl)-9H-carbazol-3-yl)-4'-phenyl-triphenylamine
(abbreviation: BCBA1BP) represented by a structural formula (63),
will be specifically described.
##STR00161##
Step 1: Synthesis of 9-(biphenyl-4-yl)-9H-carbazole
[0461] A synthetic scheme of 9-(biphenyl-4-yl)-9H-carbazole in Step
1 is shown in the following (N-1).
##STR00162##
[0462] In a 200-mL three-neck flask, 12 g. (50 mmol) of
4-bromobiphenyl, 8.4 g (50 mmol) of carbazole, 230 mg (1 mmol) of
palladium acetate (abbreviation: Pd(OAc)(II)), 1.8 g (3.0 mmol) of
1,1-bis(diphenylphosphino)ferrocene (abbreviation: DPPF), and 13 g
(180 mmol) of sodium tert-butoxide were put, and the atmosphere of
the flask was substituted by nitrogen. Then, 80 mL of dehydrated
xylene was added to this mixture. This mixture was deaerated while
being stirred under low pressure, and the mixture was stirred under
a nitrogen atmosphere at 120.degree. C. for 7.5 hours to be
reacted.
[0463] After completion of the reaction, about 600 mL of heated
toluene was added to this suspension, and filtrated twice through
Florisil, alumina, and then Celite. The obtained filtrate was
concentrated, and hexane was added thereto. The mixture was
recrystallized to obtain 14 g of an objective white powder at a
yield of 87%.
Step 2: Synthesis of 9-(biphenyl-4-yl)-3-bromo-9H-carbazole
[0464] A synthetic scheme of 9-(biphenyl-4-yl)-3-bromo-9H-carbazole
in Step 2 is shown in the following (N-2).
##STR00163##
[0465] After 3.1 g (10 mmol) of 9-(biphenyl-4-yl)-9H-carbazole was
dissolved in 100 mL of chloroform in a 200-mL conical flask, 1.8 g
(10 mmol) of N-bromo succinimide (abbreviation: NBS) was added to
this solution. After that, this mixture was stirred at room
temperature for 24 hours. After completion of the reaction, this
mixture solution was washed with water, and magnesium sulfate was
added thereto to remove moisture. This mixture solution was
filtrated, and the obtained filtrate was concentrated and dried to
obtain 3.7 g of an objective white powder at a yield of 95%.
Step 3: Synthesis of [9-(biphenyl-4-yl)-9H-carbazol-3-yl]boronic
Acid
[0466] A synthetic scheme of
[9-(biphenyl-4-yl)-9H-carbazol-3-yl]boronic acid in Step 3 is shown
in the following (N-3).
##STR00164##
[0467] In a 500-mL three-neck flask, 8.0 g (20 mmol) of
9-(4-biphenyl)-3-bromo-9H-carbazole was put, and the atmosphere in
the flask was substituted by nitrogen. Then, 200 mL of
tetrahydrofuran (abbreviation: THF) was added thereto to reach
-78.degree. C. After that, 16 mL (24 mmol) of an n-butyllithium
hexane solution (1.6 mol/L) was dropped onto this mixture solution,
and the solution was stirred for 2 hours. Then, 4.0 mL (40 mmol) of
trimethyl borate was added to this reaction mixture, and the
mixture was stirred at -78.degree. C. for 2 hours and at room
temperature for 18 hours. After the reaction, 50 mL of 1M dilute
hydrochloric acid was added to this reaction solution, and the
mixture was stirred for 3 hours. This mixture was extracted with
toluene, and the obtained organic layer was washed with a saturated
saline solution. After the washing, magnesium sulfate was added to
the organic layer to remove moisture. This suspension was
filtrated, the obtained filtrate was concentrated, and hexane was
added thereto. The mixture was irradiated with supersonic and then
recrystallized to obtain 6.6 g of an objective white powder at a
yield of 91%.
Step 4: Synthesis of
4-[9-(biphenyl-4-yl)-9H-carbazol-3-yl)-4'-phenyl-triphenylamine
(Abbreviation: BCBA1BP)
[0468] A synthetic scheme of
4-[9-(biphenyl-4-yl)-9H-carbazol-3-yl)-4'-phenyl-triphenylamine in
Step 4 is shown in the following (N-4).
##STR00165##
[0469] In a 50-mL three-neck flask, 1.2 g (3.0 mmol) of
4-bromo-4'-phenyl-triphenylamine, 1.1 g (3.0 mmol) of
[9-(biphenyl-4-yl)-9H-carbazol-3-yl]boronic acid, 6.0 mg (0.03
mmol) of palladium(II) acetate, and 18 mg (0.06 mmol) of
tri(o-tolyl)phosphine were put, and 20 mL of toluene, mL of
ethanol, and 3 mL of a potassium carbonate solution (2 mol/L) were
added to this mixture. This mixture was deaerated while being
stirred under low pressure. After the deaeration, the mixture was
stirred under a nitrogen atmosphere at 90.degree. C. for 6.5 hours
to be reacted.
[0470] After the reaction, 150 mL of toluene was added to this
reaction mixture, and this suspension was filtrated through
Florisil and then Celite. The obtained filtrate was washed with
water. Then, magnesium sulfate was added to remove moisture. This
suspension was filtrated through Florisil, alumina, silica gel, and
then Celite to obtain filtrate. The obtained filtrate was
concentrated, and acetone and methanol were added thereto. The
mixture was irradiated with supersonic and then recrystallized to
obtain 1.5 g of an objective white powder at a yield of 79%.
[0471] An Rf value of the objective substance by a silica gel thin
layer chromatography (TLC) (developing solvent, ethyl
acetate:hexane=1:10) was 0.45 and that of
4-bromo-4'-phenyl-triphenylamine was 0.68.
[0472] A compound which was obtained through the above Step 4 was
measured by a nuclear magnetic resonance method (.sup.1H NMR). The
measurement result is described below, and the .sup.1H NMR chart is
shown in FIGS. 51A and 51B. It was found from the measurement
result that the carbazole derivative of the present invention,
BCBA1BP (abbreviation) represented by the above structural formula
(63), was obtained. .sup.1H NMR (CDCl.sub.3, 300 MHz): .delta.
(ppm)=7.06 (t, J=7.2 Hz, 1H), 7.20-7.72 (m, 29H), 7.83 (d, J=8.4
Hz, 2H), 8.19 (d, J=7.8 Hz, 1H), 8.35 (s, 1H).
[0473] Molecular weight of the above compound was measured by a
TOF-MS detector (Waters Micromass LCT Premier, manufactured by
Waters). A mixture solution containing acetonitrile and 0.1% of a
formic acid solution (mixture rate of acetonitrile and the formic
acid solution, 80/20 vol/vol) was used as a solvent. Accordingly, a
main peak with a molecular weight of 638.27 (mode is ES+) was
detected, and it was confirmed that an objective BCBA1BP
(abbreviation) was obtained.
[0474] In addition, an absorption spectrum of PCBA1BP
(abbreviation) (measurement range: 200 nm to 800 nm) was measured.
In the case of the toluene solution, an absorption peak on a long
wavelength side was observed at around 336 nm, and in the case of
the thin film, an absorption peak on a long wavelength side was
observed at around 342 nm.
[0475] In addition, an emission spectrum of PCBA1BP (abbreviation)
(measurement range: 370 nm to 550 nm) was measured. In the case of
the toluene solution, a maximum emission wavelength was 394 nm
(excitation wavelength: 350 nm), and in the case of the thin film,
a maximum emission wavelength was 408 nm (excitation wavelength:
301 nm). Since the measurement method of an absorption spectrum and
an emission spectrum is similar to that of Embodiment 1, the
description is omitted.
[0476] The result of measuring the thin film using a photoelectron
spectrometer (AC-2, manufactured by Riken Keiki Co., Ltd.) under
the atmosphere indicated that the HOMO level of PCBA1BP
(abbreviation) was -5.48 eV. The Tauc plot of the absorption
spectrum of the thin film revealed that the absorption edge was
3.19 eV. Thus, the energy gap in the solid state was estimated to
be 3.19 eV, which means that the LUMO level of PCBA1BP
(abbreviation) is -2.29 eV.
[0477] An oxidation-reduction reaction characteristic of PCBA1BP
(abbreviation) was examined by a cyclic voltammetry (CV)
measurement. Since the measurement method is similar to that of
Embodiment 1, the description is omitted.
[0478] According to the calculation similar to that of Embodiment
1, the HOMO level of PCBA1BP (abbreviation) was found to be=-5.43
[eV]. In addition, the oxidation peak took a similar value even
after the 100 cycles. Accordingly, it was found that repetition of
the oxidation reduction between an oxidation state and a neutral
state had favorable characteristics.
[0479] In addition, the glass transition temperature of PCBA1BP
(abbreviation) was examined with a differential scanning
calorimetry (Pyris 1 DSC, manufactured by Perkin Elmer Co., Ltd.).
According to the measurement results, it was found that the glass
transition temperature was 122.degree. C. In this manner, PCBA1BP
(abbreviation) has a high glass transition temperature and
favorable heat resistance. In addition, the crystallization peak
does not exist; thus, it was found that PCBA1BP (abbreviation) is a
substance which is hard to be crystallized.
[0480] Note that the efficiency, the drive voltage at a luminance
of about 1000 cd/m.sup.2, and the reliability of a light-emitting
element formed using PCBA1BP (abbreviation) which was synthesized
in Embodiment 12 in a manner similar to that of Embodiment 5 for a
hole-transporting layer, favorable values equivalent to those of
the light-emitting element 8 which was formed using PCBBiNB in
Embodiment 10 were obtained. When the drive voltage of the
light-emitting element was 4.0 V, the luminance and the current
value were 1031 cd/m.sup.2 and 0.72 mA, respectively, and the
light-emitting element exhibited 89% of the initial luminance when
driven for 180 hours.
Embodiment 13
[0481] In Embodiment 13, a synthetic method of a carbazole
derivative of the present invention,
4-[9-(biphenyl-4-yl)-9H-carbazol-3-yl)-4'-(1-naphthyl)triphenylamine
(abbreviation: BCBANB) represented by a structural formula (364),
will be specifically described.
##STR00166##
Step 1: Synthesis of 4-bromotriphenylamine
[0482] A synthetic scheme of 4-bromotriphenylamine in Step 1 is
shown in the following (O-1).
##STR00167##
[0483] To 1.5 L of an ethyl acetate solution containing 54.0 g (220
mmol) of triphenylamine, 35.6 g (200 mmol) of N-bromo succinimide
(abbreviation: NBS) was added. Then, the mixture was stirred for 24
hours. After the obtained suspension was concentrated to 1 L, the
concentrated suspension was washed with 1 L of an aqueous solution
containing 5% of sodium acetate. After the washing, this solution
was further concentrated to about 50 mL. Then, methanol was added
to the concentrated solution and the solution was precipitated. The
obtained precipitate was filtered and dried to obtain 46.5 g of an
objective white powder at a yield of 73%.
Step 2: Synthesis of 4-(1-naphthyl)triphenylamine
[0484] A synthetic scheme of 4-(1-naphthyl)triphenylamine in Step 2
is shown in the following (0-2).
##STR00168##
[0485] In a 20 mL three-neck flask, 9.7 g (30 mmol) of
4-bromotriphenylamine, 5.7 g (33 mmol) of 1-naphthaleneboronic
acid, 67 mg (0.3 mmol) of palladium(II) acetate, and 91 g (0.3
mmol) of tri(o-tolyl)phosphine were put, and 20 mL of toluene, 20
mL of ethanol, and 20 mL of a potassium carbonate solution (2
mol/L) were added to this mixture. This mixture was deaerated while
being stirred under low pressure. After the deaeration, the mixture
was stirred under a nitrogen atmosphere at 90.degree. C. for 2
hours to be reacted.
[0486] After the reaction, 150 mL of toluene was added to this
reaction mixture, and this suspension was filtrated through
Florisil, silica gel, and then Celite. The obtained filtrate was
washed with sodium hydrogen carbonate solution and water in this
order, and magnesium sulfate was added thereto to dry the filtrate.
After the drying, this suspension was filtrated through Florisil,
alumina, silica gel, and then Celite to obtain filtrate. The
obtained filtrate was concentrated and dried to obtain 11 g of an
objective light-yellow solid at a yield of 99%.
[0487] An Rf value of the objective substance by a silica gel thin
layer chromatography (TLC) (developing solvent, ethyl
acetate:hexane=1:10) was 0.48 and that of 4-bromotriphenylamine was
0.55.
[0488] A compound which was obtained through the above Step 2 was
measured by a nuclear magnetic resonance method (.sup.1H NMR). It
was found from the measurement result that the compound of the
present invention represented by the above structural formula (364)
was obtained. .sup.1H NMR (CDCl.sub.3, 300 MHz): .delta. (ppm)=7.07
(t, J=7.5 Hz, 1H), 7.22-7.61 (m, 21H), 7.83 (d, J=7.8 Hz, 1H),
7.88-7.91 (m, 1H), 8.02-8.05 (m, 1H).
Step 3: Synthesis of 4-bromo-4'-(1-naphthyl)triphenylamine
[0489] A synthetic scheme of 4-bromo-4'-(1-naphthyl)triphenylamine
in Step 3 is shown in the following (0-3).
##STR00169##
[0490] After 11 g (30 mmol) of 4-(1-naphthyl)triphenylamine was
dissolved in 300 mL of ethyl acetate in a 500-mL recovery flask,
5.3 g (30 mmol) of N-bromo succinimide (abbreviation: NBS) was
added to this solution. After that, this mixture was stirred at
room temperature for 168 hours. After completion of the reaction,
this mixture solution was washed with water, and magnesium sulfate
was added thereto to remove moisture. This mixture solution was
filtrated, and the obtained filtrate was concentrated and purified
by silica gel column chromatography (developing solvent,
toluene:hexane=1:4). The obtained fraction was concentrated, and
methanol was added thereto. The mixture was irradiated with
supersonic and then recrystallized to obtain 7.8 g of an objective
white powder at a yield of 43%.
Step 4: Synthesis of
4-[9-(biphenyl-4-yl)-9H-carabazol-3-yl]-4'-(1-naphthyl)triphenylamine
(Abbreviation: BCBANB)
[0491] A synthetic scheme of
4-[9-(biphenyl-4-yl)-9H-carabazol-3-yl]-4'-(1-naphthyl)triphenylamine
in Step 4 is shown in the following (0-4).
##STR00170##
[0492] In a 100-mL three-neck flask, 1.35 g (3.0 mmol) of
4-bromo-4'-(1-naphthyl)triphenylamine, 1.1 g (3.0 mmol) of
[9-(biphenyl-4-yl)-9H-carbazol-3-yl]boronic acid, 6.0 mg (0.02
mmol) of palladium(II) acetate, and 9.0 mg (0.06 mmol) of
tri(o-tolyl)phosphine were put, and 20 mL of toluene, 5 mL of
ethanol, and 3 mL of a potassium carbonate solution (2 mol/L) were
added to this mixture. This mixture was deaerated while being
stirred under low pressure. After the deaeration, the mixture was
stirred under a nitrogen atmosphere at 90.degree. C. for 3 hours to
be reacted.
[0493] After the reaction, 150 mL of toluene was added to this
reaction mixture, and this suspension was filtrated through
Florisil, silica gel, and then Celite. The obtained filtrate was
washed with water. Then, magnesium sulfate was added to remove
moisture. This suspension was filtrated through Florisil, alumina,
silica gel, and then Celite to obtain filtrate. The obtained
filtrate was concentrated and purified by silica gel column
chromatography (developing solvent, toluene:hexane=1:4). The
obtained fraction was concentrated, and acetone and methanol were
added thereto. The mixture was irradiated with supersonic and then
recrystallized to obtain 1.0 g of an objective white powder at a
yield of 50%.
[0494] An Rf value of the objective substance by a silica gel thin
layer chromatography (TLC) (developing solvent, ethyl
acetate:hexane=1:10) was 0.45 and that of
4-bromo-4'-(1-naphthyl)triphenylamine was 0.66.
[0495] A compound which was obtained through the above Step 4 was
measured by a nuclear magnetic resonance method (.sup.1H NMR). The
measurement result is described below, and the .sup.1H NMR chart is
shown in FIGS. 52A and 52B. It was found from the measurement
result that the carbazole derivative of the present invention,
BCBANB (abbreviation) represented by the above structural formula
(364), was obtained. .sup.1H NMR (CDCl.sub.3, 300 MHz): .delta.
(ppm)=7.08 (t, J=6.9 Hz, 1H), 7.28-7.71 (m, 28H), 7.82-7.86 (m,
3H), 7.89-7.92 (m, 1H), 8.04-8.07 (m, 1H), 8.20 (d, J=7.8 Hz, 1H),
8.37 (d, J=1.2 Hz, 1H).
[0496] Molecular weight of the above compound was measured by a
TOF-MS detector (Waters Micromass LCT Premier, manufactured by
Waters). A mixture solution containing acetonitrile and 0.1% of a
formic acid solution (mixture rate of acetonitrile and the forminc
acid solution, 80/20 vol/vol) was used as a solvent. Accordingly, a
main peak with a molecular weight of 556.52 (mode is ES+) was
detected, and it was confirmed that an objective BCBANB
(abbreviation) was obtained.
[0497] In addition, an absorption spectrum of BCBANB (abbreviation)
(measurement range: 200 nm to 800 nm) was measured. In the case of
the toluene solution, an absorption peak on a long wavelength side
was observed at around 335 nm, and in the case of the thin film, an
absorption peak on a long wavelength side was observed at around
344 nm.
[0498] In addition, an emission spectrum of BCBANB (abbreviation)
(measurement range: 370 nm to 550 nm) was measured. In the case of
the toluene solution, a maximum emission wavelength was 410 nm
(excitation wavelength: 345 nm), and in the case of the thin film,
a maximum emission wavelength was 422 nm (excitation wavelength:
328 nm).
[0499] Since the measurement method of an absorption spectrum and
an emission spectrum is similar to that of Embodiment 1, the
description is omitted.
[0500] The result of measuring the thin film using a photoelectron
spectrometer (AC-2, manufactured by Riken Keiki Co., Ltd.) under
the atmosphere indicated that the HOMO level of BCBANB
(abbreviation) was -5.42 eV. The Tauc plot of the absorption
spectrum of the thin film revealed that the absorption edge was
3.19 eV. Thus, the energy gap in the solid state was estimated to
be 3.19 eV, which means that the LUMO level of BCBANB
(abbreviation) is -2.23 eV
[0501] An oxidation-reduction reaction characteristic of BCBANB
(abbreviation) was examined by a cyclic voltammetry (CV)
measurement. Since the measurement method is similar to that of
Embodiment 1, the description is omitted.
[0502] According to the calculation similar to that of Embodiment
1, the HOMO level of BCBANB (abbreviation) was found to be=-5.45
[eV]. In addition, the oxidation peak took a similar value even
after the 100 cycles. Accordingly, it was found that repetition of
the oxidation reduction between an oxidation state and a neutral
state had favorable characteristics.
[0503] In addition, the glass transition temperature of BCBANB
(abbreviation) was examined with a differential scanning
calorimetry (Pyris 1 DSC, manufactured by Perkin Elmer Co., Ltd.).
According to the measurement results, it was found that the glass
transition temperature was 130.degree. C. In this manner, BCBANB
(abbreviation) has a high glass transition temperature and
favorable heat resistance. In addition, the crystallization peak
does not exist; thus, it was found that BCBANB (abbreviation) is a
substance which is hard to be crystallized.
[0504] Note that the efficiency, the drive voltage at a luminance
of about 1000 cd/m.sup.2, and the reliability of a light-emitting
element formed using BCBANB (abbreviation) which was synthesized in
Embodiment 13 in a manner similar to that of Embodiment 5 for a
hole-transporting layer, favorable values equivalent to those of
the light-emitting element 8 which was formed using PCBBiNB in
Embodiment 10 were obtained. When the drive voltage of the
light-emitting element was 4.0 V, the luminance and the current
value were 848 cd/m.sup.2 and 0.52 mA, respectively.
Embodiment 14
[0505] In Embodiment 14, a synthetic method of a carbazole
derivative of the present invention,
4-[9-(biphenyl-4-yl)-9H-carbazol-3-yl)-4'-(1-naphthyl).sub.4''-phenyl-tri-
phenylamine (abbreviation: BCBBiNB) represented by a structural
formula (366), will be specifically described.
##STR00171##
Step 1: Synthesis of
4-[9-(biphenyl-4-yl)-9H-carbazol-3-yl)-4'-(1-naphthyl)-4''-phenyl-triphen-
ylamine (Abbreviation: BCBBiNB)
[0506] A synthetic scheme of
4-[9-(biphenyl-4-yl)-9H-carbazol-3-yl)-4'-(1-naphthyl).sub.4''-phenyl-tri-
phenylamine in Step 1 is shown in the following (P-1).
##STR00172##
[0507] In a 100-mL three-neck flask, 1.6 g (3.0 mmol) of
4-bromo-4'-(1-naphthyl)-4''-phenyl-triphenylamine, 1.1 g (3.0 mmol)
of [9-(biphenyl-4-yl)-9H-carbazol-3-yl]boronic acid, 6.0 mg (0.03
mmol) of palladium(II) acetate, and 18 mg (0.03 mmol) of
tri(o-tolyl)phosphine were put, and 20 mL of toluene, mL of
ethanol, and 3 mL of a potassium carbonate solution (2 mol/L) were
added to this mixture. This mixture was deaerated while being
stirred under low pressure. After the deaeration, the mixture was
stirred under a nitrogen atmosphere at 90.degree. C. for 6.5 hours
to be reacted.
[0508] After the reaction, 150 mL of toluene was added to this
reaction mixture, and this suspension was filtrated through
Florisil, silica gel, and then Celite. The obtained filtrate was
washed with water. Then, magnesium sulfate was added to remove
moisture. This suspension was filtrated through Florisil, alumina,
silica gel, and then Celite to obtain filtrate. The obtained
filtrate was concentrated and purified by silica gel column
chromatography (developing solvent, toluene:hexane=1:4). The
obtained fraction was concentrated, and acetone and methanol were
added thereto. The mixture was irradiated with supersonic and then
recrystallized to obtain 1.4 g of an objective white powder at a
yield of 60%.
[0509] An Rf value of the objective substance by a silica gel thin
layer chromatography (TLC) (developing solvent, ethyl
acetate:hexane=1:10) was 0.26 and that of
4-bromo-4'-(1-naphthyl)-4''-phenyl-triphenylamine was 0.46.
[0510] A compound which was obtained through the above Step 1 was
measured by a nuclear magnetic resonance method (.sup.1H NMR). The
measurement result is described below, and the .sup.1H NMR chart is
shown in FIGS. 53A and 53B. It was found from the measurement
result that the carbazole derivative of the present invention,
BCBBiNB (abbreviation) represented by the above structural formula
(366), was obtained. .sup.1H NMR (CDCl.sub.3, 300 MHz): .delta.
(ppm)=7.30-7.71 (m, 33H), 7.82-7.86 (m, 3H), 7.90-7.93 (m, 1H),
8.05-8.08 (m, 1H), 8.20 (d, J=7.8 Hz, 1H), 8.38 (d, J=1.5 Hz,
1H).
[0511] Molecular weight of the above compound was measured by a
TOF-MS detector (Waters Micromass LCT Premier, manufactured by
Waters). A mixture solution containing acetonitrile and 0.1% of a
formic acid solution (mixture rate of acetonitrile and the forminc
acid solution, 80/20 vol/vol) was used as a solvent. Accordingly, a
main peak with a molecular weight of 765.32 (mode is ES+) was
detected, and it was confirmed that an objective BCBBiNB
(abbreviation) was obtained.
[0512] In addition, an absorption spectrum of BCBBiNB
(abbreviation) (measurement range: 200 nm to 800 nm) was measured.
In the case of the toluene solution, an absorption peak on a long
wavelength side was observed at around 342 nm, and in the case of
the thin film, an absorption peak on a long wavelength side was
observed at around 351 nm.
[0513] In addition, an emission spectrum of BCBBiNB (abbreviation)
(measurement range: 370 nm to 550 nm) was measured. In the case of
the toluene solution, a maximum emission wavelength was 409 nm
(excitation wavelength: 355 nm), and in the case of the thin film,
a maximum emission wavelength was 433 nm (excitation wavelength:
336 nm).
[0514] Since the measurement method of an absorption spectrum and
an emission spectrum is similar to that of Embodiment 1, the
description is omitted.
[0515] The result of measuring the thin film using a photoelectron
spectrometer (AC-2, manufactured by Riken Keiki Co., Ltd.) under
the atmosphere indicated that the HOMO level of BCBBiNB
(abbreviation) was -5.35 eV. The Tauc plot of the absorption
spectrum of the thin film revealed that the absorption edge was
3.18 eV Thus, the energy gap in the solid state was estimated to be
3.18 eV, which means that the LUMO level of BCBBiNB (abbreviation)
is -2.17 eV.
[0516] An oxidation-reduction reaction characteristic of BCBBiNB
(abbreviation) was examined by a cyclic voltammetry (CV)
measurement. Since the measurement method is similar to that of
Embodiment 1, the description is omitted.
[0517] According to the calculation similar to that of Embodiment
1, the HOMO level of BCBBiNB (abbreviation) was found to be=-5.42
[eV]. In addition, the oxidation peak took a similar value even
after the 100 cycles. Accordingly, it was found that repetition of
the oxidation reduction between an oxidation state and a neutral
state had favorable characteristics.
[0518] In addition, the glass transition temperature of BCBBiNB
(abbreviation) was examined with a differential scanning
calorimetry (Pyris 1 DSC, manufactured by Perkin Elmer Co., Ltd.).
According to the measurement results, it was found that the glass
transition temperature was 143.degree. C. In this manner, BCBBiNB
(abbreviation) has a high glass transition temperature and
favorable heat resistance. In addition, the crystallization peak
does not exist; thus, it was found that BCBBiNB (abbreviation) is a
substance which is hard to be crystallized.
[0519] Note that the efficiency, the drive voltage at a luminance
of about 1000 cd/m.sup.2, and the reliability of a light-emitting
element formed using BCBBiNB (abbreviation) which was synthesized
in Embodiment 14 in a manner similar to that of Embodiment 5 for a
hole-transporting layer, favorable values equivalent to those of
the light-emitting element 8 which was formed using PCBBiNB in
Embodiment 10 were obtained. When the drive voltage of the
light-emitting element was 4.0 V, the luminance and the current
value were 996 cd/m.sup.2 and 0.59 mA, respectively, and the
light-emitting element exhibited 84% of the initial luminance when
driven for 180 hours.
Embodiment 15
[0520] In Embodiment 15, a synthetic method of a carbazole
derivative of the present invention,
4-{9-[4-(1-naphthyl)phenyl]-9H-carbazol-3-yl}-4'-phenyl-triphenylamine
(abbreviation: NBCBA1BP) represented by a structural formula (386),
will be specifically described.
##STR00173##
Step 1: Synthesis of 9-(4-bromophenyl)-9H-carbazole
[0521] A synthetic scheme of 9-(4-bromophenyl)-9H-carbazole in Step
1 is shown in the following (Q-1).
##STR00174##
[0522] In a 300-mL three-neck flask, 56 g (240 mmol) of
1,4-dibromobenzene, 31 g (180 mmol) of 9H-carabazole, 4.6 g (24
mmol) of copper(I) iodide, 2.1 g (8.0 mmol) of 18-crown-6-ether, 66
g (480 mmol) of potassium carbonate, and 8 mL of
1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)pyrimidinone (abbreviation:
DMPU) were put, and the mixture was stirred under a nitrogen
atmosphere at 180.degree. C. for 6 hours.
[0523] After the reaction, this suspension was filtrated, and the
filtrate was washed with dilute hydrochloric acid, a saturated
sodium hydrogen carbonate solution, and a saturated saline solution
in this order. Then, moisture was removed by magnesium sulfate.
This suspension was filtrated, and the obtained filtrate was
concentrated and purified by silica gel column chromatography
(developing solvent, toluene:hexane=9:1). The obtained fraction was
concentrated, and chloroform and hexane were added thereto. The
mixture was irradiated with supersonic and then recrystallized to
obtain 21 g of an objective light brown plate-like crystal at a
yield of 35%.
Step 2: Synthesis of 9-[4-(1-naphthyl)phenyl]-9H-carbazole
[0524] A synthetic scheme of 9-[4-(1-naphthyl)phenyl]-9H-carbazole
in Step 2 is shown in the following (Q-2).
##STR00175##
[0525] In a 100-mL three-neck flask, 4.8 g (15 mmol) of
9-(4-bromophenyl)-9H-carbazole, 2.6 g (15 mmol) of
1-naphthaleneboronic acid, 2.0 mg (0.01 mmol) of palladium(II)
acetate, and 6.0 mg (0.02 mmol) of tri(o-tolyl)phosphine were put,
and 20 mL of toluene, 10 mL of ethanol, and 10 mL of a potassium
carbonate solution (2 mol/L) were added to this mixture. This
mixture was deaerated while being stirred under low pressure. After
the deaeration, the mixture was stirred under a nitrogen atmosphere
at 90.degree. C. for 9 hours to be reacted.
[0526] After the reaction, 150 mL of toluene was added to this
reaction mixture, and this suspension was filtrated through
Florisil and then Celite. The obtained filtrate was washed with
water. Then, magnesium sulfate was added to remove moisture. This
suspension was filtrated through Florisil, alumina, silica gel, and
then Celite to obtain filtrate. The obtained filtrate was
concentrated, and acetone and methanol were added thereto. The
mixture was irradiated with supersonic and then recrystallized to
obtain 5.0 g of an objective white powder at a yield of 90%.
[0527] An Rf value of the objective substance by a silica gel thin
layer chromatography (TLC) (developing solvent, ethyl
acetate:hexane=1:10) was 0.46 and that of
9-(4-bromophenyl)-9H-carbazole was 0.54.
Step 3: Synthesis of
3-bromo-9-[4-(1-naphthyl)phenyl]-9H-carbazole
[0528] A synthetic scheme of
3-bromo-9-[4-(1-naphthyl)phenyl]-9H-carbazole in Step 3 is shown in
the following (Q-3).
##STR00176##
[0529] After 5.0 g (14 mmol) of
9-[4-(1-naphthyl)phenyl]-9H-carbazole was dissolved in a mixture
solvent of 50 mL of toluene and 250 mL of ethyl acetate in a 300-mL
conical flask, 2.5 g (14 mmol) of N-bromo succinimide
(abbreviation: NBS) was added to this solution. After that, this
mixture was stirred at room temperature for 168 hours. After
completion of the reaction, this mixture solution was filtrated
through Florisil and then Celite. Then, the obtained filtrate was
washed with water, and magnesium sulfate was added thereto to
remove moisture. This mixture solution was filtrated, the obtained
filtrate was concentrated, and hexane was added thereto. Then, the
mixture was irradiated with supersonic to obtain 6.1 g of an
objective white powder at a yield of 99%.
Step 4: Synthesis of 9-[4-(1-naphthyl)phenyl]-9H-carbazol-3-boronic
acid
[0530] A synthetic scheme of
9-[4-(1-naphthyl)phenyl]-9H-carbazol-3-boronic acid in Step 4 is
shown in the following (Q-4).
##STR00177##
[0531] In a 500-mL three-neck flask, 5.0 g (14 mmol) of
3-bromo-9-[4-(1-naphthyl)phenyl]-9H-carbazole was put, and the
atmosphere in the flask was substituted by nitrogen. Then, 200 mL
of tetrahydrofuran (abbreviation: THF) was added thereto to reach
-78.degree. C. 11 mL (17 mmol) of an n-butyllithium hexane solution
(1.6 mol/L) was dropped onto this mixture solution, and the
solution was stirred for 4 hours. After that, 2.7 mL (27 mmol) of
trimethyl borate was added to this reaction mixture, and the
mixture was stirred at -78.degree. C. for 2 hours and at room
temperature for 16 hours. After the reaction, 50 mL of 1M dilute
hydrochloric acid was added to this reaction solution, and the
mixture was stirred for 4 hours. This mixture was extracted with
toluene, and the obtained organic layer was washed with a saturated
saline solution. After the washing, magnesium sulfate was added to
the organic layer to remove moisture. This suspension was
filtrated, the obtained filtrate was concentrated, and chloroform
and hexane were added thereto. The mixture was irradiated with
supersonic and then recrystallized to obtain 3.5 g of an objective
white powder at a yield of 63%.
Step 5: Synthesis of
4-{9-[4(1-naphthyl)phenyl]-9H-carbazol-3-yl}-4'-phenyl-triphenylamine
(Abbreviation: NBCBA1BP)
[0532] A synthetic scheme of
4-{9-[4(1-naphthyl)phenyl]-9H-carbazol-3-yl}-4'-phenyl-triphenylamine
in Step 5 is shown in the following (Q-5).
##STR00178##
[0533] In a 50-mL three-neck flask, 1.0 g (2.5 mmol) of
4-bromo-4'-phenyl-triphenylamine, 1.0 g (2.5 mmol) of
9-[4-(1-naphthyl)phenyl]-9H-carbazol-3-boronic acid, 4.0 mg (0.02
mmol) of palladium(II) acetate, and 6.0 mg (0.02 mmol) of
tri(o-tolyl)phosphine were put, and 20 mL of toluene, 5 mL of
ethanol, and 2.5 mL of a potassium carbonate solution (2 mol/L)
were added to this mixture. This mixture was deaerated while being
stirred under low pressure. After the deaeration, the mixture was
stirred under a nitrogen atmosphere at 90.degree. C. for 13 hours
to be reacted.
[0534] After the reaction, 150 mL of toluene was added to this
reaction mixture, and this suspension was filtrated through
Florisil, silica gel, and then Celite. The obtained filtrate was
washed with water. Then, magnesium sulfate was added to remove
moisture. This suspension was filtrated through Florisil, alumina,
silica gel, and then Celite to obtain filtrate. The obtained
filtrate was concentrated, and acetone and methanol were added
thereto. The mixture was irradiated with supersonic and then
recrystallized to obtain 1.2 g of an objective white powder at a
yield of 70%.
[0535] An Rf value of the objective substance by a silica gel thin
layer chromatography (TLC) (developing solvent, ethyl
acetate:hexane=1:10) was 0.41 and that of
4-bromo-4'-phenyl-triphenylamine was 0.62.
[0536] A compound which was obtained through the above Step 5 was
measured by a nuclear magnetic resonance method (.sup.1H NMR). The
measurement result is described below, and the .sup.1H NMR chart is
shown in FIGS. 54A and 54B. It was found from the measurement
result that the carbazole derivative of the present invention,
NBCBA1BP (abbreviation) represented by the above structural formula
(386), was obtained. .sup.1H NMR (CDCl.sub.3, 300 MHz): .delta.
(ppm)=7.06 (t, J=6.6 Hz, 1H), 7.21-7.77 (m, 30H), 7.92-7.98 (m,
2H), 8.04-8.08 (m, 1H), 8.22 (d, J=7.8 Hz, 1H), 8.37 (d, J=1.5 Hz,
1H).
[0537] In addition, an absorption spectrum of NBCBA1BP
(abbreviation) (measurement range: 200 nm to 800 nm) was measured.
In the case of the toluene solution, an absorption peak on a long
wavelength side was observed at around 333 nm, and in the case of
the thin film, an absorption peak on a long wavelength side was
observed at around 340 nm.
[0538] In addition, an emission spectrum of NBCBA1BP (abbreviation)
(measurement range: 370 nm to 550 nm) was measured. In the case of
the toluene solution, a maximum emission wavelength was 393 nm
(excitation wavelength: 350 nm), and in the case of the thin film,
a maximum emission wavelength was 488 nm (excitation wavelength:
302 nm).
[0539] Since the measurement method of an absorption spectrum and
an emission spectrum is similar to that of Embodiment 1, the
description is omitted.
[0540] The result of measuring the thin film using a photoelectron
spectrometer (AC-2, manufactured by Riken Keiki Co., Ltd.) under
the atmosphere indicated that the HOMO level of NBCBA1BP
(abbreviation) was -5.53 eV. The Tauc plot of the absorption
spectrum of the thin film revealed that the absorption edge was
3.22 eV. Thus, the energy gap in the solid state was estimated to
be 3.22 eV, which means that the LUMO level of NBCBA1BP
(abbreviation) is -2.31 eV.
[0541] An oxidation-reduction reaction characteristic of NBCBA1BP
(abbreviation) was examined by a cyclic voltammetry (CV)
measurement. Since the measurement method is similar to that of
Embodiment 1, the description is omitted.
[0542] According to the calculation similar to that of Embodiment
1, the HOMO level of NBCBA1BP (abbreviation) was found to be=-5.43
[eV]. In addition, the oxidation peak took a similar value even
after the 100 cycles. Accordingly, it was found that repetition of
the oxidation reduction between an oxidation state and a neutral
state had favorable characteristics.
[0543] In addition, the glass transition temperature of NBCBA1BP
(abbreviation) was examined with a differential scanning
calorimetry (Pyris 1 DSC, manufactured by Perkin Elmer Co., Ltd.).
According to the measurement results, it was found that the glass
transition temperature was 132.degree. C. In this manner, NBCBA1BP
(abbreviation) has a high glass transition temperature and
favorable heat resistance. In addition, the crystallization peak
does not exist; thus, it was found that NBCBA1BP (abbreviation) is
a substance which is hard to be crystallized.
[0544] Note that the efficiency, the drive voltage at a luminance
of about 1000 cd/m.sup.2, and the reliability of a light-emitting
element formed using NBCBA1BP (abbreviation) which was synthesized
in Embodiment 15 in a manner similar to that of Embodiment 5 for a
hole-transporting layer, favorable values equivalent to those of
the light-emitting element 8 which was formed using PCBBiNB in
Embodiment 10 were obtained. When the drive voltage of the
light-emitting element was 3.6 V, the luminance and the current
value were 773 cd/m.sup.2 and 0.47 mA, respectively.
Embodiment 16
[0545] In Embodiment 16, a synthetic method of a carbazole
derivative of the present invention,
4-[9-(1-naphthyl)-9H-carbazol-3-yl]-4'-phenyl-triphenylamine
(abbreviation: NCBA1BP) represented by a structural formula (395),
will be specifically described.
##STR00179##
Step 1: Synthesis of 9-(1-naphthyl)-9H-carbazole
[0546] A synthetic scheme of 9-(1-naphthyl)-9H-carbazole in Step 1
is shown in the following (R-1).
##STR00180##
[0547] In a 500-mL three-neck flask, 21 g (100 mmol) of
1-bromonaphthalene, 17 g (100 mmol) of carabazole, 0.1 g (5.0 mmol)
of copper(I) iodide, 0.7 g (2.5 mmol) of 18-crown-6-ether, 33 g
(240 mmol) of potassium carbonate, and 80 mL of
1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)pyrimidinone (abbreviation:
DMPU) were put, and the mixture was stirred under a nitrogen
atmosphere at 170.degree. C. for 6 hours. Then, 10 g (50 mmol) of
1-bromonaphthalene, 2.0 g (10 mmol) of copper(I) iodide, and 2.6 g
(10 mmol) of 18-crown-6-ether were further added to this reaction
mixture, and the mixture was further stirred at 170.degree. C. for
7.5 hours. After that, 10 g (50 mmol) of 1-bromonaphthalene was
further added to this reaction mixture, and the mixture was further
stirred at 180.degree. C. for 6 hours.
[0548] After the reaction, about 200 mL of toluene and about 100 mL
of hydrochloric acid (1 mol/L) were added to this reaction mixture,
and the mixture was filtered through Celite. The obtained filtrate
was filtrated through Florisil and Celite. The obtained filtrate
was separated into an organic layer and an aqueous layer. After
this organic layer was washed with hydrochloric acid (1 mol/L) and
water in this order, magnesium sulfate was added to remove
moisture. This suspension was filtered through Florisil and Celite.
Then, hexane was added to the oily substance obtained by
concentrating the obtained filtrate, and the mixture was irradiated
with supersonic and then recrystallized to obtain 22 g of an
objective white powder at a yield of 75%.
[0549] An Rf value of the objective substance by a silica gel thin
layer chromatography (TLC) (developing solvent, ethyl
acetate:hexane=1:10) was 0.61, that of 1-bromonaphthalene was 0.74,
and that of carbazole was 0.24.
Step 2: Synthesis of 3-bromo-9-(1-naphthyl)-9H-carbazole
[0550] A synthetic scheme of 3-bromo-9-(1-naphthyl)-9H-carbazole in
Step 2 is shown in the following (R-2).
##STR00181##
[0551] After 5.9 g (20 mmol) of 9-(1-naphthyl)-9H-carbazole was
dissolved in a mixture solvent of 50 mL of toluene and 50 mL of
ethyl acetate in a 500-mL conical flask, 3.6 g (20 mmol) of N-bromo
succinimide (abbreviation: NBS) was added to this solution. After
that, this mixture was stirred at room temperature for 170 hours.
After completion of the reaction, this mixture solution was washed
with water, and magnesium sulfate was added thereto to remove
moisture. This mixture solution was filtrated, and the obtained
filtrate was concentrated and dried to obtain 7.4 g of an objective
white powder at a yield of 99%.
[0552] An Rf value of the objective substance by a silica gel thin
layer chromatography (TLC) (developing solvent, ethyl
acetate:hexane=1:10) was 0.43 and that of
9-(1-naphthyl).sub.9H-carbazole was 0.35.
Step 3: Synthesis of 9-(1-naphthyl)9H-carbazol-3-boronic Acid
[0553] A synthetic scheme of 9-(1-naphthyl)9H-carbazol-3-boronic
acid in Step 3 is shown in the following (R-3).
##STR00182##
[0554] In a 500-mL three-neck flask, 3.7 g (10 mmol) of
9-(1-naphthyl)9H-carbazole was put, and the atmosphere in the flask
was substituted by nitrogen. Then, 200 mL of tetrahydrofuran
(abbreviation: THF) was added thereto, and the mixture was stirred
at -78.degree. C. Then, 7 mL (13 mmol) of an n-butyllithium hexane
solution (1.6 mol/L) was dropped onto this mixture solution, and
the solution was stirred for 2 hours. After that, 2 mL (20 mmol) of
trimethyl borate was added to this reaction mixture, and the
mixture was stirred at -78.degree. C. for 3 hours and at room
temperature for 16 hours. After the reaction, 50 mL of 1M dilute
hydrochloric acid wes added to this reaction solution, and the
mixture was stirred for 4 hours. This mixture was extracted with
ethyl acetate, and the obtained organic layer was washed with a
saturated saline solution. After the washing, magnesium sulfate was
added to the organic layer to remove moisture. This suspension was
filtrated, the obtained filtrate was concentrated, and chloroform
and hexane were added thereto. The mixture was irradiated with
supersonic and then recrystallized to obtain 2.6 g of an objective
yellow powder at a yield of 78%.
Step 4: Synthesis of
4-[9-(1-naphthyl)-9H-carbazol-3-yl]-4'-phenyl-triphenylamine
Abbreviation: NCBA1BP)
[0555] A synthetic scheme of
4-[9-(1-naphthyl)-9H-carbazol-3-yl]-4'-phenyl-triphenylamine
(abbreviation: NCBA1BP) in Step 4 is shown in the following
(R-4).
##STR00183##
[0556] In a 50-mL three-neck flask, 1.2 g (3.0 mmol) of
4-bromo-4'-phenyl-triphenylamine, 1.0 g (3.0 mmol) of
9-(1-naphthyl)9H-carbazol-3-boronic acid, 6.0 mg (0.03 mmol) of
palladium(II) acetate, and 0.03 mg (18 mmol) of
tri(o-tolyl)phosphine were put, and 15 mL of toluene, 5 mL of
ethanol, and 3 mL of a potassium carbonate solution (2 mol/L) were
added to this mixture. This mixture was deaerated while being
stirred under low pressure. After the deaeration, the mixture was
stirred under a nitrogen atmosphere at 90.degree. C. for 6.5 hours
to be reacted.
[0557] After the reaction, 150 mL of toluene was added to this
reaction mixture, and this suspension was filtrated through
Florisil, silica gel, and then Celite. The obtained filtrate was
washed with water. Then, magnesium sulfate was added to remove
moisture. This suspension was filtrated through Florisil, alumina,
silica gel, and then Celite to obtain filtrate. The obtained
filtrate was concentrated and purified by silica gel column
chromatography (developing solvent, toluene:hexane=1:3). The
obtained fraction was concentrated, and methanol was added thereto.
The mixture was irradiated with supersonic and then recrystallized
to obtain 0.5 g of an objective white powder at a yield of 25%.
[0558] An Rf value of the objective substance by a silica gel thin
layer chromatography (TLC) (developing solvent, ethyl
acetate:hexane=1:10) was 0.34 and that of
4-bromo-4'-phenyl-triphenylamine was 0.54.
[0559] A compound which was obtained through the above Step 4 was
measured by a nuclear magnetic resonance method (.sup.1H NMR). The
measurement result is described below, and the .sup.1H NMR chart is
shown in FIGS. 55A and 55B. It was found from the measurement
result that the carbazole derivative of the present invention,
NCBA1BP (abbreviation) represented by the above structural formula
(395), was obtained. .sup.1H NMR (CDCl.sub.3, 300 MHz): .delta.
(ppm)=7.00-7.07 (m, 3H), 7.19-8.00 (m, 25H), 8.03-8.07 (m, 2H),
8.22-8.25 (m, 1H), 8.40 (d, J=1.5, 1H).
[0560] In addition, an absorption spectrum of NCBA1BP
(abbreviation) (measurement range: 200 nm to 800 nm) was measured.
In the case of the toluene solution, an absorption peak on a long
wavelength side was observed at around 333 nm, and in the case of
the thin film, an absorption peak on a long wavelength side was
observed at around 340 nm.
[0561] In addition, an emission spectrum of NCBA1BP (abbreviation)
(measurement range: 370 nm to 550 nm) was measured. In the case of
the toluene solution, a maximum emission wavelength was 392 nm
(excitation wavelength: 345 nm), and in the case of the thin film,
a maximum emission wavelength was 426 nm (excitation wavelength:
328 nm). Since the measurement method of an absorption spectrum and
an emission spectrum is similar to that of Embodiment 1, the
description is omitted.
[0562] The result of measuring the thin film using a photoelectron
spectrometer (AC-2, manufactured by Riken Keiki Co., Ltd.) under
the atmosphere indicated that the HOMO level of NCBA1BP
(abbreviation) was -5.44 eV The Tauc plot of the absorption
spectrum of the thin film revealed that the absorption edge was
3.19 eV. Thus, the energy gap in the solid state was estimated to
be 3.19 eV, which means that the LUMO level of NCBA1BP
(abbreviation) is -2.25 eV.
[0563] An oxidation-reduction reaction characteristic of NCBA1BP
(abbreviation) was examined by a cyclic voltammetry (CV)
measurement. Since the measurement method is similar to that of
Embodiment 1, the description is omitted. According to the
calculation similar to that of Embodiment 1, the HOMO level of
NCBA1BP (abbreviation) was found to be=-5.43 [eV]. In addition, the
oxidation peak took a similar value even after the 100 cycles.
Accordingly, it was found that repetition of the oxidation
reduction between an oxidation state and a neutral state had
favorable characteristics.
[0564] In addition, the glass transition temperature of NCBA1BP
(abbreviation) was examined with a differential scanning
calorimetry (Pyris 1 DSC, manufactured by Perkin Elmer Co., Ltd.).
According to the measurement results, it was found that the glass
transition temperature was 128.degree. C. In this manner, NCBA1BP
(abbreviation) has a high glass transition temperature and
favorable heat resistance. In addition, the crystallization peak
does not exist; thus, it was found that NCBA1BP (abbreviation) is a
substance which is hard to be crystallized.
[0565] Note that the efficiency, the drive voltage at a luminance
of about 1000 cd/m.sup.2, and the reliability of a light-emitting
element formed using NCBA1BP (abbreviation) which was synthesized
in Embodiment 16 in a manner similar to that of Embodiment 5 for a
hole-transporting layer, favorable values equivalent to those of
the light-emitting element 8 which was formed using PCBBiNB in
Embodiment 10 were obtained. When the drive voltage of the
light-emitting element was 4.0 V, the luminance and the current
value were 1198 cd/m.sup.2 and 0.82 mA, respectively.
Embodiment 17
[0566] In Embodiment 17, a synthetic method of a carbazole
derivative of the present invention,
4,4'-diphenyl-4''-(6,9-diphenyl-9H-carbazol-3-yl)triphenylamine
(abbreviation: PCBBi1BPIII) represented by a structural formula
(422), will be specifically described.
##STR00184##
Step 1: Synthesis of 3-bromo-6,9-diphenyl-9H-carbazole
[0567] A synthetic scheme of 3-bromo-6,9-diphenyl-9H-carbazole in
Step 1 is shown in the following (S-1).
##STR00185##
[0568] In a 300-mL erlenmayer flask, 4.8 g (15 mmol) of
3,9-diphenyl-9H-carbazole was put, and 250 mL of a mixture solvent
(ethyl acetate: toluene=4:1) was added to this solution. After
that, this mixture was stirred for 30 minutes. Then, 2.7 g (15
mmol) of N-bromo succinimide (abbreviation: NBS) was added to this
solution little by little, and the solution was stirred for 48
hours.
[0569] After the stirring, this mixture was washed with a saturated
sodium hydrogen carbonate solution and a saturated saline solution
in this order. After the washing, moisture of the obtained organic
layer was removed by magnesium sulfate. Then, suction filtration
was performed on this mixture and the magnesium sulfate was removed
to obtain filtrate. A small amount of ethanol was added to an oily
substance which was obtained by concentrating the obtained
filtrate. Then, the mixture was irradiated with supersonic to
precipitate a solid. The precipitated solid was collected by
suction filtration to obtain 5.4 g of a white powder-like solid at
a yield of 90%.
Step 2: Synthesis of
4,4'-diphenyl-4''-(6,9-diphenyl-9H-carbazol-3-yl)triphenylamine
(Abbreviation: PCBBi1BPIII)
[0570] A synthetic scheme of
4,4'-diphenyl-4''-(6,9-diphenyl-9H-carbazol-3-yl)triphenylamine in
Step 2 is shown in the following (S-2).
##STR00186##
[0571] In a 100-mL three-neck flask, 1.7 g (3.8 mmol) of
N,N-bis(biphenyl-4-yl)aminophenyl-4-boronic acid, 1.5 g (3.8 mmol)
of 3-bromo-6,9-diphenyl-9H-carbazole, 8.4 mg (0.038 mmol) of
palladium(II) acetate, and 0.080 mg (0.26 mmol) of
tri(o-tolyl)phosphine were put. Then, 10 mL of toluene, 2 mL of
ethanol, and 10 mL of a 2M potassium carbonate solution were added
to this mixture. After this mixture was deaerated under low
pressure, the atmosphere in the flask was substituted by nitrogen.
This mixture was stirred at 100.degree. C. for 3 hours.
[0572] After the stirring, toluene was added to this reaction
mixture, and this mixture was heated at 50.degree. C. and stirred.
After this suspension was brought back to room temperature, the
suspension was separated into an organic layer and an aqueous
layer. The obtained organic layer was washed with a saturated
sodium carbonate solution and a saturated saline solution in this
order. After the washing, magnesium sulfate was added to the
obtained organic layer to remove moisture. Suction filtration was
performed on this mixture to obtain filtrate. Suction filtration
was performed on the obtained filtrate through Celite (Wako Pure
Chemical Industries, Ltd., catalog No.: 531-16855), Florisil (Wako
Pure Chemical Industries, Ltd., catalog No.: 540-00135), and
alumina to obtain filtrate. The obtained filtrate was concentrated
and purified by silica gel column chromatography. The silica gel
column chromatography was performed by, first, using a mixture
solvent of toluene:hexane=1:4 as a developing solvent, and then
using a mixture solvent of toluene:hexane=1:1 as another developing
solvent. A solid which was obtained by concentrating the obtained
fraction was recrystallized with a mixture solvent of chloroform
and hexane to obtain 2.3 g of a white powder-like solid at a yield
of 87%.
[0573] Sublimation purification of 2.3 g of the obtained white
solid was performed by a train sublimation method. The sublimation
purification was performed under a reduced pressure of 7.0 Pa, with
a flow rate of argon at 4 mL/min, at 320.degree. C. for 18 hours to
obtain 1.8 g of the white solid at a yield of 78%.
[0574] A compound which was obtained through the above Step 2 was
measured by a nuclear magnetic resonance method (.sup.1H NMR). The
measurement result is described below, and the .sup.1H NMR chart is
shown in FIGS. 61A and 61B. It was found from the measurement
result that the carbazole derivative of the present invention,
PCBBi1BPIII (abbreviation) represented by the above structural
formula (422), was obtained. .sup.1H NMR (CDCl.sub.3, 300 MHz):
.delta. (ppm)=7.22-7.77 (m, 36H), 8.38-8.42 (m, 2H).
[0575] Molecular weight of the above compound was measured by a
TOF-MS detector (Waters Micromass LCT Premier, manufactured by
Waters). A mixture solution containing acetonitrile and 0.1% of a
formic acid solution (mixture rate of acetonitrile and the forminc
acid solution, 80/20 vol/vol) was used as a solvent. Accordingly, a
main peak with a molecular weight of 714.30 (mode is ES+) was
detected, and it was confirmed that an objective PCBBi1BPIII
(abbreviation) was obtained.
[0576] In addition, various physical properties of PCBBi1BPIII
(abbreviation) were measured as described below.
[0577] In addition, an absorption spectrum of PCBBi1BPIII
(abbreviation) (measurement range: 200 nm to 800 nm) was measured.
In the case of the toluene solution, an absorption peak on a long
wavelength side was observed at around 348 nm, and in the case of
the thin film, an absorption peak on a long wavelength side was
observed at around 352 nm. In addition, an emission spectrum of
PCBBi1BPIII (abbreviation) (measurement range: 390 nm to 550 nm)
was measured. In the case of the toluene solution, a maximum
emission wavelength was 397 nm (excitation wavelength: 358 nm), and
in the case of the thin film, a maximum emission wavelength was 439
nm (excitation wavelength: 369 nm).
[0578] The result of measuring the thin film using a photoelectron
spectrometer (AC-2, manufactured by Riken Keiki Co., Ltd.) under
the atmosphere indicated that the HOMO level of PCBBi1BPIII
(abbreviation) was -5.46 eV. The Tauc plot of the absorption
spectrum of the thin film revealed that the absorption edge was
3.21 eV Thus, the energy gap in the solid state was estimated to be
3.21 eV, which means that the LUMO level of PCBBi1BPIII
(abbreviation) is -2.25 eV.
[0579] An oxidation-reduction reaction characteristic of
PCBBi1BPIII (abbreviation) was examined by a cyclic voltammetry
(CV) measurement. Since the measurement method is similar to that
of Embodiment 1, the description is omitted. According to the
calculation similar to that of Embodiment 1, the HOMO level of
PCBBi1BPIII (abbreviation) was found to be=-41 [eV]. In addition,
the oxidation peak took a similar value even after the 100 cycles.
Accordingly, it was found that repetition of the oxidation
reduction between an oxidation state and a neutral state had
favorable characteristics.
[0580] In addition, the glass transition temperature of PCBBi1BPIII
(abbreviation) was examined with a differential scanning
calorimetry (Pyris 1 DSC, manufactured by Perkin Elmer Co., Ltd.).
According to the measurement results, it was found that the glass
transition temperature was 138.degree. C. In this manner,
PCBBi1BPIII (abbreviation) has a high glass transition temperature
and favorable heat resistance. In addition, the crystallization
peak does not exist; thus, it was found that PCBBi1BPIII
(abbreviation) is a substance which is hard to be crystallized.
[0581] Note that the efficiency, the drive voltage at a luminance
of about 1000 cd/m.sup.2, and the reliability of a light-emitting
element formed using PCBBi1BPIII (abbreviation) which was
synthesized in Embodiment 17 in a manner similar to that of
Embodiment 5 for a hole-transporting layer, favorable values
equivalent to those of the light-emitting element 8 which was
formed using PCBBiNB in Embodiment 10 were obtained. When the drive
voltage of the light-emitting element was 4.2 V, the luminance and
the current value were 1070 cd/m.sup.2 and 0.75 mA, respectively,
and the light-emitting element exhibited 74% of the initial
luminance when driven for 360 hours.
Embodiment 18
[0582] In Embodiment 18, a synthetic method of a carbazole
derivative of the present invention,
3,3'-dimethyl-4''-phenyl-4-(9-phenyl-9H-carbazol-3-yl)-triphenylamine
(abbreviation: PCBA1BPIV) represented by a structural formula
(423), will be specifically described.
##STR00187##
Step 1: Synthesis of 3,3'-dimethyl-4''-phenyl-triphenylamine
[0583] A synthetic scheme of
3,3'-dimethyl-4''-phenyl-triphenylamine in Step 1 is shown in the
following (T-1).
##STR00188##
[0584] In a 100-mL three-neck flask, 5.8 g (25 mmol) of
4-bromobiphenyl, 4.9 g (25 mmol) of m,m'-Ditolylamine, 3.0 (30
mmol) of sodium tert-butoxide, and 140 mg (0.25 mmol) of
bis(dibenzylideneacetone)palladium(0) were put, and the atmosphere
of the flask was substituted by nitrogen. Then, 50 mL of dehydrated
xylene was added to this mixture. This mixture was deaerated while
being stirred under low pressure. After the deaeration, 1.0 mL (0.5
mmol) of tri(tert-butyl)phosphine (10 wt % hexane solution) was
added thereto. This mixture was stirred under a nitrogen atmosphere
at 130.degree. C. for 1.5 hours to be reacted.
[0585] After the reaction, 80 mL of toluene and 420 mL of hexane
were added to this reaction mixture, and this suspension was
filtrated through Florisil, silica gel, and then Celite. The
obtained filtrate was washed with water. Then, magnesium sulfate
was added to remove moisture. This suspension was filtrated through
Florisil and then Celite to obtain filtrate. The obtained filtrate
was concentrated, and methanol was added thereto. The mixture was
irradiated with supersonic and then recrystallized to obtain 8.5 g
of an objective white powder at a yield of 97%.
[0586] A compound which was obtained through the above Step 1 was
measured by a nuclear magnetic resonance method (.sup.1H NMR).
.sup.1H NMR (CDCl.sub.3, 300 MHz): .delta. (ppm)=2.28 (s, 6H), 6.85
(d, J=6.9, 2H), 6.91-6.95 (m, 4H), 7.09-7.18 (m, 4H), 7.29 (t,
J=7.5, 1H), 7.38-7.48 (m, 4H), 7.56-7.59 (m, 2H).
Step 2: Synthesis of
4-bromo-3,3'-dimethyl-4''-phenyl-triphenylamine
[0587] A synthetic scheme of
4-bromo-3,3'-dimethyl-4''-phenyl-triphenylamine in Step 2 is shown
in the following (T-2).
##STR00189##
[0588] After 2.5 g (24 mmol) of
3,3'-dimethyl-4''-phenyl-triphenylamine was dissolved in 200 mL of
ethyl acetate in a 200-mL conical flask, 4.3 g (24 mmol) of N-bromo
succinimide (abbreviation: NBS) was added to this solution. After
that, this mixture was stirred at room temperature for 48 hours.
After completion of the reaction, this mixture solution was washed
with water, and magnesium sulfate was added thereto to remove
moisture. This mixture solution was filtrated and the obtained
filtrate was concentrated and dried to obtain 9.1 g of an objective
caramel-like solid at a yield of 88%.
Step 3: Synthesis of
3,3'-dimethyl-4''-phenyl-4-(9-phenyl-9H-carbazol-3-yl)-triphenylamine
(Abbreviation: PCBA1BPIV)
[0589] A synthetic scheme of
3,3'-dimethyl-4''-phenyl-4-(9-phenyl-9H-carbazol-3-yl)-triphenylamine
in Step 3 is shown in the following (T-3).
##STR00190##
[0590] In a 300-mL recovery flask, 1.7 g (4.0 mmol) of
4-bromo-3,3'-dimethyl-4''-phenyl-triphenylamine, 1.4 g (5.0 mmol)
of 9-phenyl-9H-carbazol-3-boronic acid, 5.0 mg (0.02 mmol) of
palladium(II) acetate, and 6.0 mg (0.02 mmol) of
tri(o-tolyl)phosphine were put, and 30 mL of toluene, 5 mL of
ethanol, and 3.5 mL of a potassium carbonate solution (2 mol/L)
were added to this mixture. This mixture was deaerated while being
stirred under low pressure. After the deaeration, the mixture was
stirred under a nitrogen atmosphere at 90.degree. C. for 3 hours to
be reacted.
[0591] After the reaction, 150 mL of toluene was added to this
reaction mixture, and this suspension was filtrated through
Florisil and then Celite. The obtained filtrate was washed with
water. Then, magnesium sulfate was added to remove moisture. This
suspension was filtrated through Florisil, alumina, silica gel, and
then Celite to obtain filtrate. The obtained filtrate was
concentrated and purified by silica gel column chromatography
(developing solvent, toluene:hexane=1:4). The obtained fraction was
concentrated, and hexane and acetone were added thereto. The
mixture was irradiated with supersonic and then recrystallized to
obtain 1.0 g of an objective white powder at a yield of 42%.
[0592] An Rf value of the objective substance by a silica gel thin
layer chromatography (TLC) (developing solvent, ethyl
acetate:hexane=1:10) was 0.51 and that of
4-bromo-3,3'-dimethyl-4''-phenyl-triphenylamine was 0.62.
[0593] A compound which was obtained through the above Step 3 was
measured by a nuclear magnetic resonance method (.sup.1H NMR). The
measurement result is described below, and the .sup.1H NMR chart is
shown in FIGS. 62A to 62C. It was found from the measurement result
that the carbazole derivative of the present invention, PCBA1BPIV
(abbreviation) represented by the above structural formula (423),
was obtained. .sup.1H NMR (CDCl.sub.3, 300 MHz): .delta. (ppm)=2.26
(s, 3H), 2.30 (s, 3H), 6.86 (d, J=7.8, 1H), 6.99-7.59 (m, 25H),
8.09-8.13 (m, 2H).
[0594] Molecular weight of the above compound was measured by a
TOF-MS detector (Waters Micromass LCT Premier, manufactured by
Waters). A mixture solution containing acetonitrile and 0.1% of a
formic acid solution (mixture rate of acetonitrile and the forminc
acid solution, 80/20 vol/vol) was used as a solvent. Accordingly, a
main peak with a molecular weight of 591.28 (mode is ES+) was
detected, and it was confirmed that an objective PCBA1BPIV
(abbreviation) was obtained.
[0595] In addition, various physical properties of PCBA1BPIV
(abbreviation) were measured as described below.
[0596] In addition, an absorption spectrum of PCBA1BPIV
(abbreviation) (measurement range: 200 nm to 800 nm) was measured.
In the case of the toluene solution, an absorption peak on a long
wavelength side was observed at around 325 nm, and in the case of
the thin film, an absorption peak on a long wavelength side was
observed at around 329 nm. In addition, an emission spectrum of
PCBA1BPIV (abbreviation) (measurement range: 370 nm to 550 nm) was
measured. In the case of the toluene solution, a maximum emission
wavelength was 393 nm (excitation wavelength: 330 nm), and in the
case of the thin film, a maximum emission wavelength was 422 nm
(excitation wavelength: 357 nm).
[0597] The result of measuring the thin film using a photoelectron
spectrometer (AC-2, manufactured by Riken Keiki Co., Ltd.) under
the atmosphere indicated that the HOMO level of PCBA1BPIV
(abbreviation) was -5.57 eV. The Tauc plot of the absorption
spectrum of the thin film revealed that the absorption edge was
3.36 eV. Thus, the energy gap in the solid state was estimated to
be 3.36 eV, which means that the LUMO level of PCBA1BPIV
(abbreviation) is -2.21 eV.
[0598] In addition, the glass transition temperature of PCBA1BPIV
(abbreviation) was examined with a differential scanning
calorimetry (Pyris 1 DSC, manufactured by Perkin Elmer Co., Ltd.).
According to the measurement results, it was found that the glass
transition temperature was 105.degree. C. In this manner, PCBA1BPIV
(abbreviation) has a high glass transition temperature and
favorable heat resistance. In addition, the crystallization peak
does not exist; thus, it was found that PCBA1BPIV (abbreviation) is
a substance which is hard to be crystallized.
[0599] Note that the efficiency, the drive voltage at a luminance
of about 1000 cd/m.sup.2, and the reliability of a light-emitting
element formed using PCBA1BPIV (abbreviation) which was synthesized
in Embodiment 18 in a manner similar to that of Embodiment 5 for a
hole-transporting layer, favorable values equivalent to those of
the light-emitting element 8 which was formed using PCBBiNB in
Embodiment 10 were obtained. When the drive voltage of the
light-emitting element was 4.0 V, the luminance and the current
value were 924 cd/m.sup.2 and 0.61 mA, respectively.
Embodiment 19
[0600] In Embodiment 19, a synthetic method of a carbazole
derivative of the present invention,
4,4'-di(2-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)-triphenylamine
(abbreviation: PCBNBB.beta.) represented by a structural formula
(345), will be specifically described.
##STR00191##
Step 1: Synthesis of 4,4'-di(2-naphthyl)-triphenylamine
[0601] A synthetic scheme of 4,4'-di(2-naphthyl)-triphenylamine in
Step 1 is shown in the following (U-1).
##STR00192##
[0602] in a 300-mL three-neck flask, 6.0 g (15 mmol) of
4,4'-dibromotriphenylamine, 6.2 g (36 mmol) of 2-naphthaleneboronic
acid, 16 mg (0.1 mmol) of palladium(II) acetate, and 21 mg (0.1
mmol) of tri(o-tolyl)phosphine were put, and 50 mL of toluene, 20
mL of ethanol, and 20 mL of a potassium carbonate solution (2
mol/L) were added to this mixture. This mixture was deaerated while
being stirred under low pressure. After the deaeration, the mixture
was stirred under a nitrogen atmosphere at 90.degree. C. for 4.5
hours to be reacted.
[0603] After the reaction, 150 mL of toluene was added to this
reaction mixture, and this suspension was filtrated through
Florisil, silica gel, and then Celite. The obtained filtrate was
washed with water. Then, magnesium sulfate was added to remove
moisture. This suspension was filtrated through Florisil, alumina,
silica gel, and then Celite to obtain filtrate. The obtained
filtrate was concentrated, and hexane was added thereto. The
mixture was irradiated with supersonic and then recrystallized to
obtain 5.6 g of an objective white powder at a yield of 75%.
[0604] An Rf value of the objective substance by a silica gel thin
layer chromatography (TLC) (developing solvent, ethyl
acetate:hexane=1:10) was 0.53 and that of
4,4'-dibromotriphenylamine was 0.78.
Step 2: Synthesis of
4-bromo-4',4''-di(2-naphthyl)-triphenylamine
[0605] A synthetic scheme of
4-bromo-4',4''-di(2-naphthyl)-triphenylamine in Step 2 is shown in
the following (U-2).
##STR00193##
[0606] After 4.0 g (8.0 mmol) of 4,4'-di(2-naphthyl)-triphenylamine
was dissolved in a mixture solvent of 200 mL of toluene and 250 mL
of ethyl acetate in a 500-mL conical flask, 1.4 g (8 mmol) of
N-bromo succinimide (abbreviation: NBS) was added to this solution.
After that, this mixture was stirred at room temperature for 96
hours. After completion of the reaction, this mixture solution was
washed with water, and magnesium sulfate was added thereto to
remove moisture. This suspension was filtrated through Florisil and
then Celite. The obtained filtrate was concentrated and purified by
silica gel column chromatography (developing solvent,
toluene:hexane=1:4). The obtained fraction was concentrated, and
acetone and hexane were added thereto. The mixture was irradiated
with supersonic and then recrystallized to obtain 3.4 g of an
objective white powder at a yield of 61%.
[0607] A compound which was obtained through the above Step 2 was
measured by a nuclear magnetic resonance method (.sup.1H NMR). The
measurement result is described below. .sup.1H NMR (CDCl.sub.3, 300
MHz): .delta. (ppm)=7.09 (d, J=8.4, 2H), 7.24 (d, J=7.8, 4H), 7.40
(d, J=8.4, 2H), 7.47-7.51 (m, 4H), 7.66 (d, J=8.1, 4H), 7.73-7.76
(m, 2H), 7.85-7.93 (m, 6H), 8.03 (s, 2H).
Step 3: Synthesis of
4,4'-di(2-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)-triphenylamine
(abbreviation: PCBNBB.beta.)
[0608] A synthetic scheme of
4,4'-di(2-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)-triphenylamine
in Step 3 is shown in the following (U-3).
##STR00194##
[0609] In a 50-mL three-neck flask, 1.0 g (1.7 mmol) of
4-bromo-4',4''-di(2-naphthyl)-triphenylamine, 0.6 g (2.0 mmol) of
9-phenyl-9H-carbazol-3-boronic acid, 2.2 mg (1.0 .mu.mol) of
palladium(II) acetate, and 3.0 mg (10 .mu.mol) of
tri(o-tolyl)phosphine were put, and 20 mL of toluene, 3 mL of
ethanol, and 2.0 mL of a potassium carbonate solution (2 mol/L)
were added to this mixture. This mixture was deaerated while being
stirred under low pressure. After the deaeration, the mixture was
stirred under a nitrogen atmosphere at 90.degree. C. for 14 hours
to be reacted.
[0610] After the reaction, 150 mL of toluene was added to this
reaction mixture, and this suspension was filtrated through
Florisil, silica gel, alumina, and then Celite. The obtained
filtrate was concentrated and purified by silica gel column
chromatography (developing solvent, toluene:hexane=1:4). The
obtained fraction was concentrated, and methanol, chloroform,
acetone, and hexane were added thereto. The mixture was irradiated
with supersonic and then recrystallized to obtain 1.5 g of an
objective light-yellow powder at a yield of 95%.
[0611] An Rf value of the objective substance by a silica gel thin
layer chromatography (TLC) (developing solvent, ethyl
acetate:hexane=1:10) was 0.31 and that of
4-bromo-4',4''-di(2-naphthyl)-triphenylamine was 0.56.
[0612] A compound which was obtained through the above Step 3 was
measured by a nuclear magnetic resonance method (.sup.1H NMR). The
measurement result is described below, and the .sup.1H NMR chart is
shown in FIGS. 63A and 63B. It was found from the measurement
result that the carbazole derivative of the present invention,
PCBNBB.beta. (abbreviation) represented by the above structural
formula (345), was obtained. .sup.1H NMR (CDCl.sub.3, 300 MHz):
.delta. (ppm)=7.29-7.90 (m, 34H), 8.03 (s, 2H), 8.16 (d, J=7.2,
1H), 8.34 (d, J=1.5, 1H).
[0613] Molecular weight of the above compound was measured by a
TOF-MS detector (Waters Micromass LCT Premier, manufactured by
Waters). A mixture solution containing acetonitrile and 0.1% of a
formic acid solution (mixture rate of acetonitrile and the formic
acid solution, 80/20 vol/vol) was used as a solvent. Accordingly, a
main peak with a molecular weight of 739.32 (mode is ES+) was
detected, and it was confirmed that an objective PCBNBB.beta.
(abbreviation) was obtained.
[0614] In addition, various physical properties of PCBNBB.beta.
(abbreviation) were measured as described below.
[0615] In addition, an absorption spectrum of PCBNBB.beta.
(abbreviation) (measurement range: 200 nm to 800 nm) was measured.
In the case of the toluene solution, an absorption peak on a long
wavelength side was observed at around 357 nm, and in the case of
the thin film, an absorption peak on a long wavelength side was
observed at around 366 nm. In addition, an emission spectrum of
PCBNBB.beta. (abbreviation) (measurement range: 390 nm to 550 nm)
was measured. In the case of the toluene solution, a maximum
emission wavelength was 415 nm (excitation wavelength: 360 nm), and
in the case of the thin film, a maximum emission wavelength was 449
nm (excitation wavelength: 376 nm).
[0616] The result of measuring the thin film using a photoelectron
spectrometer (AC-2, manufactured by Riken Keiki Co., Ltd.) under
the atmosphere indicated that the HOMO level of PCBNBB.beta.
(abbreviation) was -5.36 eV. The Tauc plot of the absorption
spectrum of the thin film revealed that the absorption edge was
3.06 eV. Thus, the energy gap in the solid state was estimated to
be 3.06 eV, which means that the LUMO level of PCBNBB.beta.
(abbreviation) is -2.30 eV.
[0617] An oxidation-reduction reaction characteristic of
PCBNBB.beta. (abbreviation) was examined by a cyclic voltammetry
(CV) measurement. Since the measurement method is similar to that
of Embodiment 1, the description is omitted. According to the
calculation similar to that of Embodiment 1, the HOMO level of
PCBNBB.beta. (abbreviation) was found to be=-5.41 [eV]. In
addition, the oxidation peak took a similar value even after the
100 cycles. Accordingly, it was found that repetition of the
oxidation reduction between an oxidation state and a neutral state
had favorable characteristics.
[0618] In addition, the glass transition temperature of
PCBNBB.beta. (abbreviation) was examined with a differential
scanning calorimetry (Pyris 1 DSC, manufactured by Perkin Elmer
Co., Ltd.). According to the measurement results, it was found that
the glass transition temperature was 129.degree. C. In this manner,
PCBNBB.beta. (abbreviation) has a high glass transition temperature
and favorable heat resistance. In addition, the crystallization
peak does not exist; thus, it was found that PCBNBB.beta.
(abbreviation) is a substance which is hard to be crystallized.
[0619] Note that the efficiency, the drive voltage at a luminance
of about 1000 cd/m.sup.2, and the reliability of a light-emitting
element formed using PCBNBB.beta. (abbreviation) which was
synthesized in Embodiment 19 in a manner similar to that of
Embodiment 5 for a hole-transporting layer, favorable values
equivalent to those of the light-emitting element 8 which was
formed using PCBBiNB in Embodiment 10 were obtained. When the drive
voltage of the light-emitting element was 4.4 V, the luminance and
the current value were 1104 cd/m.sup.2 and 0.74 mA, respectively,
and the light-emitting element exhibited 75% of the initial
luminance when driven for 650 hours.
Embodiment 20
[0620] In Embodiment 20, a synthetic method of a carbazole
derivative of the present invention,
4-pheny-4'-(9-phenyl-9H-carbazol-3-yl)-4''-(9-phenylfluoren-9-yl)-triphen-
ylamine (abbreviation: PCBBiFLP) represented by a structural
formula (424), will be specifically described. Note that the above
compound is the carbazole derivative represented by the general
formula (1) in which R.sup.1 is hydrogen, R.sup.2 is a phenyl
group, l is 0, m is 1, n is 0, .alpha..sup.2 is a 1,4-phenylene
group, .alpha..sup.4 is a 1,4-phenylene group, Ar.sup.1 is a
biphenyl-4-yl group, Ar.sup.2 is a fluoren-9-yl group, and the
ninth position of the fluoren-9-yl group is substituted by a phenyl
group.
##STR00195##
Step 1: Synthesis of 4-bromo-4'-phenyl-diphenylamine
[0621] A synthetic scheme of 4-bromo-4'-phenyl-diphenylamine in
Step 1 is shown in the following (V-1).
##STR00196##
[0622] After 37 g (150 mmol) of 4-phenyl-diphenylamine was
dissolved in 400 mL of ethyl acetate in a 1000-mL conical flask, 27
g (150 mmol) of N-bromo succinimide (abbreviation: NBS) was added
to this solution. After that, this mixture was stirred at room
temperature for 24 hours.
[0623] After completion of the reaction, this mixture solution was
washed with water, and magnesium sulfate was added thereto to
remove moisture. This mixture solution was filtrated through
Florisil, silica gel, alumina, and then Celite, the obtained
filtrate was concentrated, and toluene and hexane were added
thereto. The mixture was irradiated with supersonic and then
recrystallized to obtain 4.0 g of an objective white powder. In
addition, the filtrate which was obtained at the time of this
recrystallization was purified by silica gel column chromatography
(developing solvent, toluene:hexane=1:4). The obtained fraction was
concentrated, and methanol was added thereto. The mixture was
irradiated with supersonic and then recrystallized to obtain 4.5 g
of an objective white powder. Thus, in total, 8.5 g of an objective
white powder was obtained at a yield of 73%.
Step 2: Synthesis of
4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)-diphenylamine
[0624] A synthetic scheme of
4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)-diphenylamine in Step 2 is
shown in the following (V-2).
##STR00197##
[0625] In a 200-mL three-neck flask, 16 g (50 mmol) of
4-bromo-4'-phenyl-diphenylamine, 16 g (55 mmol) of
9-phenyl-9H-carbazol-3-boronic acid, 110 mg (0.4 mmol) of
palladium(II) acetate, and 150 mg (0.4 mmol) of
tri(o-tolyl)phosphine were put, and 70 mL of toluene, 5 mL of
ethanol, and 23 mL of a potassium carbonate solution (2 mol/L) were
added to this mixture. This mixture was deaerated while being
stirred under low pressure. After the deaeration, the mixture was
stirred under a nitrogen atmosphere at 90.degree. C. for 7.5 hours
to be reacted.
[0626] After the reaction, 150 mL of toluene was added to this
reaction mixture, and this suspension was filtrated through
Florisil, silica gel, and then Celite. The obtained filtrate was
washed with water. Then, magnesium sulfate was added to remove
moisture. This suspension was filtrated through Florisil, alumina,
silica gel, and then Celite to obtain filtrate. The obtained
filtrate was concentrated and purified by silica gel column
chromatography (developing solvent, toluene:hexane=1:4). The
obtained fraction was concentrated, and chloroform and methanol
were added thereto. The mixture was irradiated with supersonic and
then recrystallized to obtain 10 g of an objective light-yellow
powder at a yield of 41%.
Step 3: Synthesis of 9-(4-bromophenyl)-9-phenylfluorene
[0627] A synthetic scheme of 9-(4-bromophenyl)-9-phenylfluorene in
Step 3 is shown in the following (V-3).
##STR00198##
[0628] In a 100-mL three-neck flask, 1.2 g (50 mmol) of magnesium
was put, the mixture was stirred under low pressure for 30 minutes,
and the magnesium was activated. After the flask was cooled to room
temperature and is made to have a nitrogen atmosphere, several
drops of dibromoethane were added, so that foam formation and heat
generation were confirmed. After 12 g (50 mmol) of 2-bromobiphenyl
dissolved in 10 mL of diethyl ether was slowly dropped into this
mixture, the mixture was stirred and heated under reflux for 2.5
hours and made into a Grignard reagent.
[0629] In a 500-mL three-neck flask, 10 g (40 mmol) of
4-bromobenzophenone and 100 mL of diethyl ether were put. After the
Grignard reagent which was synthesized in advance was slowly
dropped into this mixture, the mixture was stirred and heated under
reflux for 9 hours
[0630] After the reaction, this mixture was filtrated to obtain
filtrate. The obtained filtrate was dissolved in 150 mL of ethyl
acetate, a 1N-hydrochloric acid solution was added thereto, and the
mixture was stirred for 2 hours. An organic layer of this solution
was washed with water. Then, magnesium sulfate was added to remove
moisture. This suspension was filtrated and the obtained filtrate
was concentrated to obtain a candy-like substance.
[0631] In a 500-mL recovery flask, this candy-like substance, 50 mL
of glacial acetic acid, and 1.0 mL of hydrochloric acid were put,
and the mixture was stirred under a nitrogen atmosphere at
130.degree. C. for 1.5 hours to be reacted. After the reaction,
this reactiom mixture solution was filtrated to obtain filtrate.
The obtained filtrate was washed with water, a sodium hydroxide
aqueous solution, water, and methanol in this order to obtain 11 g
of an objective white power at a yield of 69%.
Step 4: Synthesis of
4-pheny-4'-(9-phenyl-9H-carbazol-3-yl)-4''-(9-phenylfluoren-9-yl)-triphen-
ylamine (Abbreviation: PCBBiFLP)
[0632] A synthetic scheme of
4-pheny-4'-(9-phenyl-9H-carbazol-3-yl)-4''-(9-phenylfluoren-9-yl)-triphen-
ylamine in Step 4 is shown in the following (V-4).
##STR00199##
[0633] In a 100-mL three-neck flask, 1.2 g (3.0 mmol) of
9-(4-bromophenyl)-9-phenylfluorene, 1.5 g (3.0 mmol) of
4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)-diphenylamine, 0.4 mg (4.0
mmol) of sodium tert-butoxide, and 17 mg (0.03 mmol) of
bis(dibenzylideneacetone)palladium(0) were put, and the atmosphere
of the flask was substituted by nitrogen. Then, 20 mL of dehydrated
xylene was added to this mixture. This mixture was deaerated while
being stirred under low pressure. After the deaeration, 0.2 mL (0.1
mmol) of tri(tert-butyl)phosphine (10 wt % hexane solution) was
added thereto. This mixture was stirred under a nitrogen atmosphere
at 130.degree. C. for 5.5 hours to be reacted.
[0634] After the reaction, 150 mL of toluene was added to this
reaction mixture, and this suspension was filtrated through
Florisil and then Celite. The obtained filtrate was concentrated
and purified by silica gel column chromatography (developing
solvent, toluene:hexane=1:4). The obtained fraction was
concentrated, and acetone and methanol were added thereto. The
mixture was irradiated with supersonic and then recrystallized to
obtain 1.8 g of an objective white powder at a yield of 76%.
[0635] An Rf value of the objective substance by a silica gel thin
layer chromatography (TLC) (developing solvent, ethyl
acetate:hexane=1:10) was 0.35, that of
9-(4-bromophenyl)-9-phenylfluorene was 0.65, and that of
4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)-diphenylamine was 0.19.
[0636] A compound which was obtained through the above Step 4 was
measured by a nuclear magnetic resonance method (.sup.1H NMR). The
measurement result is described below, and the .sup.1H NMR chart is
shown in FIGS. 64A and 64B. It was found from the measurement
result that the carbazole derivative of the present invention,
PCBBiFLP (abbreviation) represented by the above structural formula
(424), was obtained. .sup.1H NMR (CDCl.sub.3, 300 MHz): .delta.
(ppm)=7.02 (d, J=8.7, 2H), 7.12 (d, J=8.7, 2H), 7.17-7.64 (m, 36H),
7.77 (d, J=6.9, 2H).
[0637] In addition, various physical properties of PCBBiFLP
(abbreviation) were measured as described below.
[0638] In addition, an absorption spectrum of PCBBiFLP
(abbreviation) (measurement range: 200 nm to 800 nm) was measured.
In the case of the toluene solution, an absorption peak on a long
wavelength side was observed at around 337 nm, and in the case of
the thin film, an absorption peak on a long wavelength side was
observed at around 339 nm. In addition, an emission spectrum of
PCBBiFLP (abbreviation) (measurement range: 390 nm to 550 nm) was
measured. In the case of the toluene solution, a maximum emission
wavelength was 395 nm (excitation wavelength: 343 nm), and in the
case of the thin film, a maximum emission wavelength was 425 nm
(excitation wavelength: 361 nm).
[0639] The result of measuring the thin film using a photoelectron
spectrometer (AC-2, manufactured by Riken Keiki Co., Ltd.) under
the atmosphere indicated that the HOMO level of PCBBiFLP
(abbreviation) was -5.53 eV. The Tauc plot of the absorption
spectrum of the thin film revealed that the absorption edge was
3.28 eV. Thus, the energy gap in the solid state was estimated to
be 3.28 eV, which means that the LUMO level of PCBBiFLP
(abbreviation) is -2.25 eV.
[0640] An oxidation-reduction reaction characteristic of PCBBiFLP
(abbreviation) was examined by a cyclic voltammetry (CV)
measurement. Since the measurement method is similar to that of
Embodiment 1, the description is omitted. According to the
calculation similar to that of Embodiment 1, the HOMO level of
PCBBiFLP (abbreviation) was found to be=-5.42 [eV]. In addition,
the oxidation peak took a similar value even after the 100 cycles.
Accordingly, it was found that repetition of the oxidation
reduction between an oxidation state and a neutral state had
favorable characteristics.
[0641] In addition, the glass transition temperature of PCBBiFLP
(abbreviation) was examined with a differential scanning
calorimetry (Pyris 1 DSC, manufactured by Perkin Elmer Co., Ltd.).
According to the measurement results, it was found that the glass
transition temperature was 156.degree. C. In this manner, PCBBiFLP
(abbreviation) has a high glass transition temperature and
favorable heat resistance. In addition, the crystallization peak
does not exist; thus, it was found that PCBBiFLP (abbreviation) is
a substance which is hard to be crystallized.
[0642] Note that the efficiency, the drive voltage at a luminance
of about 1000 cd/m.sup.2, and the reliability of a light-emitting
element formed using PCBBiFLP (abbreviation) which was synthesized
in Embodiment 20 in a manner similar to that of Embodiment 5 for a
hole-transporting layer, favorable values equivalent to those of
the light-emitting element 8 which was formed using PCBBiNB in
Embodiment 10 were obtained. When the drive voltage of the
light-emitting element was 4.4 V, the luminance and the current
value were 1104 cd/m.sup.2 and 0.74 mA, respectively, and the
light-emitting element exhibited 75% of the initial luminance when
driven for 650 hours.
[0643] Note that the efficiency, the drive voltage at a luminance
of about 1000 cd/m.sup.2, and the reliability of a light-emitting
element formed using PCBBiFLP (abbreviation) which was synthesized
in Embodiment 20 in a manner similar to that of Embodiment 5 for a
hole-transporting layer, favorable values equivalent to those of
the light-emitting element 8 which was formed using PCBBiNB in
Embodiment 10 were obtained. When the drive voltage of the
light-emitting element was 4.0 V, the luminance and the current
value were 1171 cd/m.sup.2 and 0.65 mA, respectively, and the
light-emitting element exhibited 74% of the initial luminance when
driven for 360 hours.
Embodiment 21
[0644] In Embodiment 21, a synthetic method of a carbazole
derivative of the present invention,
4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)-triphenylamine
(abbreviation: PCBANB) represented by a structural formula (343),
which is different from that in Embodiment 8, will be specifically
described.
##STR00200##
Step 1: Synthesis of 1-(4-bromophenyl)-naphthalene
[0645] A synthetic scheme of 1-(4-bromophenyl)-naphthalene in Step
1 is shown in the following (W-1).
##STR00201##
[0646] In a 500-mL three-neck flask, 46 g (160 mmol) of
4-bromoiodobenzene, 24 g (140 mmol) of 1-naphthaleneboronic acid,
45 mg (0.2 mmol) of palladium(II) acetate, and 60 mg (0.2 mmol) of
tri(o-tolyl)phosphine were put, and 100 mL of toluene, 20 mL of
ethanol, and 11 mL of a potassium carbonate solution (2 mol/L) were
added to this mixture. This mixture was deaerated while being
stirred under low pressure. After the deaeration, the mixture was
stirred under a nitrogen atmosphere at 90.degree. C. for 4 hours to
be reacted.
[0647] After the reaction, 500 mL of toluene was added to this
reaction mixture, and this suspension was filtrated through
Florisil and then Celite. The obtained filtrate was washed with
water. Then, magnesium sulfate was added to remove moisture. This
suspension was filtrated through Florisil and then Celite to obtain
filtrate. The obtained filtrate was concentrated and purified by
silica gel column chromatography (developing solvent, hexane). The
obtained fraction was concentrated to obtain 25 g of an objective
colorless transparent liquid at a yield of 62%.
[0648] An Rf value of the objective substance by a silica gel thin
layer chromatography (TLC) (developing solvent, hexane) was 0.38
and that of 4-bromoiodobenzene was 0.57.
[0649] [Step 2: Synthesis of
4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)-triphenylamine
(abbreviation: PCBANB)]
[0650] A synthetic scheme of
4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)-triphenylamine in
Step 2 is shown in the following (W-2).
##STR00202##
[0651] In a 100-mL three-neck flask, 2.8 g (10 mmol) of
1-(4-bromophenyl)-naphthalene, 4.1 g (10 mmol) of
4-(9-phenyl-9H-carbazol-3-yl)-diphenylamine, 1.2 g (12 mmol) of
sodium tert-butoxide, and 11 mg (0.02 mmol) of
bis(dibenzylideneacetone)palladium(0) were put, and the atmosphere
of the flask was substituted by nitrogen. Then, 30 mL of dehydrated
xylene was added to this mixture. This mixture was deaerated while
being stirred under low pressure. After the deaeration, 0.1 mL
(0.06 mmol) of tri(tert-butyl)phosphine (10 wt % hexane solution)
was added thereto. This mixture was stirred under a nitrogen
atmosphere at 110.degree. C. for 6 hours to be reacted.
[0652] After the reaction, 150 mL of toluene was added to this
reaction mixture, and this suspension was filtrated through
Florisil, silica gel, and then Celite. The obtained filtrate was
concentrated and purified by silica gel column chromatography
(developing solvent, toluene:hexane=1:4). The obtained fraction was
concentrated, and acetone and methanol were added thereto. The
mixture was irradiated with supersonic and then recrystallized to
obtain 5.2 g of an objective white powder at a yield of 85%.
[0653] Note that unless otherwise specified, for the Florisil and
the Celite which are described in each sythesitic method of the
above embodiments of the present invention, Florisil (Wako Pure
Chemical Industries, Ltd., catalog No.: 540-00135) and Celite (Wako
Pure Chemical Industries, Ltd., catalog No.: 531-16855) are used,
respectively.
[0654] The present application is based on Japanese Patent
Application serial No. 2007-312509 and Japanese Patent Application
serial No. 2008-129917 which are filed with Japan Patent Office on
Dec. 3, 2007 and May 16, 2008, respectively, the entire contents of
which are hereby incorporated by reference.
EXPLANATION OF REFERENCE
[0655] 101: substrate, 102: first electrode, 103: EL layer, 104:
second electrode, 111: first layer (hole-injecting layer), 112:
second layer (hole-transporting layer), 113: third layer
(light-emitting layer), 114: fourth layer (electron-transporting
layer), 115: fifth layer (electron-injecting layer), 301: first
electrode, 302: second electrode, 303: first EL layer, 304: second
EL layer, 305: charge generation layer, 401: driver circuit portion
(source driver circuit), 402: pixel portion, 404: sealing
substrate, 405: sealant, 407: space, 408: lead wiring, 409: FPC
(flexible printed circuit), 410: element substrate, 411: switching
TFT, 412: current control TFT, 413: first electrode, 414:
insulator, 416: EL layer, 417: second electrode, 418:
light-emitting element, 423: n-channel TFT, 424: p-channel TFT,
501: substrate, 502: first electrode, 503: second electrode, 504:
EL layer, 505: insulating layer, 506: partition layer, 611:
housing, 612: supporting base, 613: display portion, 614: speaker
portion, 615: video input terminal, 621: main body, 622: housing,
623: display portion, 624: keyboard, 625: external connection port,
626: pointing device, 631: main body, 632: housing, 633: display
portion, 634: audio input portion, 635: audio input portion, 636:
operation key, 637: external connection port, 638: antenna, 641:
main body, 642: display portion, 643: housing, 644: external
connection port, 645: remote control receiving portion, 646: image
receiving portion, 647: battery, 648: audio input portion, 649:
operation key, 650: eyepiece portion, 701: housing, 702: liquid
crystal layer, 703: backlight, 704: housing, 705: driver IC, 706:
terminal, 801: housing, 802: light source, 901: lighting device,
902: television set, 1501: substrate, 1502: first electrode, 1503:
EL layer, 1504: second electrode, 1511: first layer, 1512: second
layer, 1513: third layer, 1514: fourth layer, 1515: fifth layer
* * * * *