U.S. patent application number 13/132141 was filed with the patent office on 2011-11-24 for indenofluorenedione derivative, material for organic electroluminescent element, and organic electroluminescent element.
This patent application is currently assigned to IDEMITSU KOSAN CO., LTD.. Invention is credited to Jun Endo, Yuichiro Kawamura, Hironobu Morishita.
Application Number | 20110284827 13/132141 |
Document ID | / |
Family ID | 42233302 |
Filed Date | 2011-11-24 |
United States Patent
Application |
20110284827 |
Kind Code |
A1 |
Morishita; Hironobu ; et
al. |
November 24, 2011 |
INDENOFLUORENEDIONE DERIVATIVE, MATERIAL FOR ORGANIC
ELECTROLUMINESCENT ELEMENT, AND ORGANIC ELECTROLUMINESCENT
ELEMENT
Abstract
An indenofluorenedione derivative having a specific structure,
which is useful as a material for organic electroluminescence
devices because the derivative is excellent in heat resistance and
can be vapor-deposited on a substrate at moderate temperature. An
organic electroluminescence device including an anode, a cathode,
and an organic thin layer between the anode and the cathode, which
contains the material for organic electroluminescence devices in
the organic thin layer, is driven at a low driving voltage and has
a long lifetime.
Inventors: |
Morishita; Hironobu; (Chiba,
JP) ; Kawamura; Yuichiro; (Chiba, JP) ; Endo;
Jun; (Chiba, JP) |
Assignee: |
IDEMITSU KOSAN CO., LTD.
Tokyo
JP
|
Family ID: |
42233302 |
Appl. No.: |
13/132141 |
Filed: |
December 2, 2009 |
PCT Filed: |
December 2, 2009 |
PCT NO: |
PCT/JP2009/070243 |
371 Date: |
August 3, 2011 |
Current U.S.
Class: |
257/40 ;
257/E51.018; 558/427 |
Current CPC
Class: |
H01L 51/0052 20130101;
C09K 2211/1011 20130101; C07C 255/37 20130101; H01L 51/0055
20130101; C07C 255/35 20130101; H01L 51/0056 20130101; H01L 51/0073
20130101; C07C 2603/52 20170501; H01L 51/0059 20130101; C07C 261/04
20130101; H01L 51/0069 20130101; H01L 51/0058 20130101; H05B 33/14
20130101; C09K 11/06 20130101; H01L 51/0072 20130101; H01L 51/5048
20130101 |
Class at
Publication: |
257/40 ; 558/427;
257/E51.018 |
International
Class: |
H01L 51/54 20060101
H01L051/54; C07C 255/61 20060101 C07C255/61; C07C 255/35 20060101
C07C255/35 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 3, 2008 |
JP |
2008-308963 |
Claims
1. An indenofluorenedione derivative represented by formula (I):
##STR00055## wherein Ar.sup.1 is a condensed ring having 6 to 24
nuclear carbon atoms or a heteroring having 6 to 24 nuclear atoms,
ar.sup.1 and ar.sup.2 may be the same or different and each
independently represent a structure represented by formula (i) or
(ii): ##STR00056## wherein X.sup.1 and X.sup.2 may be the same or
different and selected from the following divalent groups
represented by formulae (a) to (g): ##STR00057## wherein R.sup.21
to R.sup.24 may be the same or different and each independently
represent a hydrogen atom, a substituted or unsubstituted
fluoroalkyl group, a substituted or unsubstituted alkyl group, a
substituted or unsubstituted cycloalkyl group, a substituted or
unsubstituted aryl group, or a substituted or unsubstituted
heterocyclic group, and R.sup.22 and R.sup.23 may bond to each
other to form a ring, R.sup.1 to R.sup.4 may be the same or
different and each independently represent a hydrogen atom, a
substituted or unsubstituted alkyl group, a substituted or
unsubstituted cycloalkyl group, a substituted or unsubstituted
alkenyl group, a substituted or unsubstituted aryl group, a
substituted or unsubstituted heterocyclic group, a halogen atom, a
substituted or unsubstituted fluoroalkyl group, a substituted or
unsubstituted alkoxyl group, a substituted or unsubstituted
fluoroalkoxyl group, a substituted or unsubstituted aryloxy group,
a substituted or unsubstituted aralkyloxy group, a substituted or
unsubstituted amino group, or cyano group, and R.sup.1 and R.sup.2,
and R.sup.3 and R.sup.4 may bond to each other to form a saturated
or unsaturated divalent group completing a ring, and Y.sup.1 and
Y.sup.4 may be the same or different and each represent --N.dbd.,
--CH.dbd., or --C(R.sup.5).dbd., wherein R.sup.5 is defined in the
same manner as in R.sup.1 to R.sup.4, and adjacent groups of
R.sup.1 to R.sup.5 may bond to each other to form a saturated or
unsaturated divalent group completing a ring, wherein the
indenofluorenedione derivative represented by formula (I) does not
include a compound represented by formula (iii), (iv), or (v):
##STR00058## wherein X.sup.1 and X.sup.2 are defined in the same
manner as in formula (I); R.sup.1 to R.sup.4 and R.sup.8 to
R.sup.17 are defined in the same manner as in R.sup.1 to R.sup.4 of
formula (I), and Y.sup.5 to Y.sup.14 are defined in the same manner
as in Y.sup.1 to Y.sup.4 of formula (I).
2. The indenofluorenedione derivative according to claim 1, which
is represented by any one of formulae (II) to (VII): ##STR00059##
wherein X.sup.1, X.sup.2, and R.sup.1 to R.sup.4 are defined in the
same manner as in formula (I) and Y.sup.21 to Y.sup.26 and Y.sup.31
to Y.sup.38 are defined in the same manner as in Y.sup.1 to Y.sup.4
of formula (I).
3. The indenofluorenedione derivative according to claim 1, wherein
at least one of Y.sup.1 to Y.sup.4, Y.sup.21 to Y.sup.26, and
Y.sup.31 to Y.sup.38 of formulae (I) to (VII) is a nitrogen
atom.
4. The indenofluorenedione derivative according to claim 1, wherein
at least one of R.sup.1 to R.sup.4 of formulae (I) to (VII) is
selected from the group consisting of a fluorine atom, a
fluoroalkyl group, a fluoroalkoxyl group, a cyano group, an aryl
group and a heterocyclic group each having at least one substituent
selected from the group consisting of fluorine, a fluoroalkyl
group, a fluoroalkoxyl group, and a cyano group.
5. A material for organic electroluminescence devices comprising
the indenofluorenedione derivative as defined in claim 1.
6. The material for organic electroluminescence devices according
to claim 5, which has a reduction potential of -1.0 V vs.
Fc.sup.+/Fc, wherein Fc is ferrocene, when measured in an
acetonitrile solution.
7. The material for organic electroluminescence devices according
to claim 5, which is a hole injecting material.
8. An organic electroluminescence device comprising an anode, a
cathode, and an organic thin layer between the anode and the
cathode, wherein the organic thin layer comprises the material for
organic electroluminescence devices as defined in claim 5.
9. The organic electroluminescence device according to claim 8,
wherein the organic thin layer is a laminate comprising a hole
injecting layer, a hole transporting layer, a light emitting layer,
and an electron transporting layer in that order from a side of the
anode.
Description
TECHNICAL FIELD BACKGROUND ART
[0001] The present invention relates to a novel indenofluorenedione
derivative, a material for organic electroluminescence device, and
an organic electroluminescence device employing the material.
BACKGROUND ART
[0002] The organic electroluminescence device
("electroluminescence" may be referred to as "EL") is a spontaneous
luminescence device in which a fluorescent material emits light by
the energy of recombination of holes injected from an anode and
electrons injected from cathode each being injected by the action
of electric field.
[0003] A two-layered structure having a hole transporting
(injecting) layer and an electron transporting, light emitting
layer and a three-layered structure having a hole transporting
(injecting) layer, a light emitting layer, and an electron
transporting (injecting) layer are well known as the laminated
structure of organic EL devices. To improve the efficiency of
recombination of injected holes and electrons of organic EL devices
of laminated structure type, the structure of device and the
production method thereof have been studied.
[0004] An aromatic diamine derivative and a diamine derivative
having an aromatic condensed ring have been used as the hole
transporting material for known organic EL devices.
[0005] However, the organic EL device containing such aromatic
diamine derivative as the hole transporting material involves the
problems of reducing the lifetime of device and increasing the
electric power to be consumed, because a high voltage is required
to obtain sufficient luminance.
[0006] To solve the above problems, it has been proposed to dope an
electron accepting compound such as Lewis acid to the hole
injecting layer or use the electron accepting compound alone (for
example, Patent Documents 1 to 4). However, the electron accepting
compounds proposed in Patent Documents 1 to 4 involve the problems,
because they are instable and difficult to handle in the production
of organic EL devices, and the stability such as heat resistance is
insufficient during the driving of organic EL devices, to reduce
the lifetime.
[0007] Tetrafluorotetracyanoquinodimethane (TCNQF.sub.4)
exemplified in Patent Documents 3, 4, etc. is highly sublimable
because of its low molecular weight and the fluorine substitution.
Therefore, this compound diffuses throughout the apparatus during
the production of organic EL device by a vacuum vapor deposition,
thereby likely contaminating the apparatus and devices being
produced (for example, Patent Document 5). [0008] Patent Document
1: JP 2003-031365A [0009] Patent Document 2: JP2001-297883A [0010]
Patent Document 3: JP2004-514257A [0011] Patent Document 4: US
2005/0255334A1 [0012] Patent Document 5: JP2008-244430A
DISCLOSURE OF THE INVENTION
[0013] The present invention has been made to solve the above
problems and an object of the present invention is to provide an
indenofluorenedione derivative which is excellent in the heat
resistance and can be vapor deposited on a substrate at moderate
temperature and a material for organic electroluminescence devices
containing the indenofluorenedione derivative. A further object is
to provide an organic electroluminescence device which is driven at
a low driving voltage and has a long lifetime.
[0014] As a result of extensive research on the skeletons of
various compounds, the inventors have paid attention to the
skeleton of indenofluorenedione. The indenofluorenedione has in one
molecule two quinone moieties (for example, .dbd.X.sup.1 and
.dbd.X.sup.2 in formula (I) described below are both .dbd.O). By
converting two quinone moieties to dicyanomethylene group,
cyanoimino group, etc., the electron accepting property is enhanced
as compared with a fluorenone derivative. The sublimation
temperature of the fluorenone derivative is low because it has a
small molecular weight and only one quinone moiety. This may result
in the contamination of apparatus during the vapor deposition for
film forming. In contrast, the indenofluorenedione derivative has
good heat resistance and moderate deposition temperature because it
has 5 or more aromatic rings or heterorings each being fused to
each other, enabling a successful production of organic EL device
by vapor deposition. In addition, the crystallization can be
reduced by the conversion of two quinone moieties to
dicyanomethylene group or cyanoimino group.
[0015] Further, the electron accepting property can be further
enhanced and the crystallinity can be further reduced by
introducing a specific substituent to the terminal rings.
[0016] The inventors have found that organic EL devices having a
low driving voltage and a long lifetime are realized by producing
the devices using the indenofluorenedione derivative having such
properties as the material for organic EL devices, particularly by
forming a hole injecting layer using the indenofluorenedione
derivative.
[0017] Namely, the present invention relates to
(1) an indenofluorenedione derivative represented by formula
(I):
##STR00001##
[0018] In formula (I), Ar.sup.1 is a condensed ring having 6 to 24
nuclear carbon atoms or a heteroring having 6 to 24 nuclear atoms,
and ar.sup.1 and ar.sup.2 are may be the same or different and each
independently represent a structure represented by formula (i) or
(ii):
##STR00002##
[0019] In formulae (i) and (ii), X.sup.1 and X.sup.2 may be the
same or different and selected from the following divalent groups
represented by formulae (a) to (g):
##STR00003##
[0020] In formulae (d) to (f), R.sup.21 to R.sup.24 may be the same
or different and each represent a hydrogen atom, a substituted or
unsubstituted fluoroalkyl group, a substituted or unsubstituted
alkyl group, a substituted or unsubstituted cycloalkyl group, a
substituted or unsubstituted aryl group, or a substituted or
unsubstituted heterocyclic group, and R.sup.22 and R.sup.23 may
bond to each other to form a ring.
[0021] In formula (I), R.sup.1 to R.sup.4 may be the same or
different and independently represent a hydrogen atom, a
substituted or unsubstituted alkyl group, a substituted or
unsubstituted cycloalkyl group, a substituted or unsubstituted
alkenyl group, a substituted or unsubstituted aryl group, a
substituted or unsubstituted heterocyclic group, a halogen atom, a
substituted or unsubstituted fluoroalkyl group, a substituted or
unsubstituted alkoxyl group, a substituted or unsubstituted
fluoroalkoxyl group, a substituted or unsubstituted aryloxy group,
a substituted or unsubstituted aralkyloxy group, a substituted or
unsubstituted amino group, or cyano group. R.sup.1 and R.sup.2, and
R.sup.3 and R.sup.4 may bond to each other to form a saturated or
unsaturated divalent group completing a ring. Y.sup.1 and Y.sup.4
may be the same or different and represent --N.dbd., --CH.dbd., or
--C(R.sup.5).dbd., wherein R.sup.5 is defined in the same manner as
in R.sup.1 to R.sup.4. Adjacent groups of R.sup.1 to R.sup.5 may
bond to each other to form a saturated or unsaturated divalent
group completing a ring.
[0022] However, the indenofluorenedione derivative represented by
formula (I) does not include the compound represented by formula
(iii), (iv), or (v).
##STR00004##
[0023] In formulae (iii), (iv), and (v), X.sup.1 and X.sup.2 are
defined in the same manner as in formula (I); R.sup.1 to R.sup.4
and R.sup.8 to R.sup.17 are defined in the same manner as in
R.sup.1 to R.sup.4 of formula (I), and Y.sup.5 to Y.sup.14 are
defined in the same manner as in Y.sup.1 to Y.sup.4 of formula
(I).
[0024] The present invention further relates to
(2) a material for organic electroluminescence devices comprising
the indenofluorenedione derivative represented by formula (I); and
(3) an organic electroluminescence device comprising an anode, a
cathode, and an organic thin layer between the anode and the
cathode, wherein the organic thin layer comprises the material for
organic electroluminescence device.
[0025] According to the present invention, an indenofluorenedione
derivative which is excellent in the heat resistance and can be
vapor-deposited on a substrate at moderate temperature and a
material for organic electroluminescence devices comprising the
indenofluorenedione derivative are provided. In addition, an
organic electroluminescence device with a long lifetime which is
driven at a low driving voltage is provided.
BRIEF DESCRIPTION OF DRAWINGS
[0026] FIG. 1 is a schematic cross-sectional view of an example of
the organic EL device of the invention.
BEST MODE FOR CARRYING OUT THE INVENTION
Indenofluorenedione Derivative
[0027] The indenofluorenedione derivative of the invention is
represented by the following formula (I):
##STR00005##
[0028] In formula (I), Ar.sup.1 is a condensed ring having 6 to 24
nuclear carbon atoms or a heteroring having 6 to 24 nuclear atoms,
preferably a condensed ring having 6 to 14 nuclear carbon atoms or
a heteroring having 6 to 14 nuclear atoms. Examples of the
condensed ring include benzene ring, naphthalene ring, fluorene
ring, 9,9-dimethylfluorene ring, and 9,9-dioctylfluorene ring.
Examples of the heteroring include pyrazine ring, pyridine ring,
quinoxaline ring, thiophene ring, benzothiophene ring,
dibenzothiophene ring, furan ring, benzofuran ring, dibenzofuran
ring, phenanthroline ring, and naphthyridine ring. The condensed
ring and the heteroring may be substituted by a substituted or
unsubstituted alkyl group, a substituted or unsubstituted
cycloalkyl group, a substituted or unsubstituted alkenyl group, a
substituted or unsubstituted aryl group, a substituted or
unsubstituted heterocyclic group, a halogen atom, a substituted or
unsubstituted fluoroalkyl group, a substituted or unsubstituted
alkoxyl group, a substituted or unsubstituted fluoroalkoxyl group,
a substituted or unsubstituted aryloxy group, a substituted or
unsubstituted aralkyloxy group, a substituted or unsubstituted
amino group, or cyano group, which are also defined as R.sup.1 to
R.sup.4 below.
[0029] In the present invention, "nuclear carbon atoms" means the
carbon atoms forming a saturated ring, an unsaturated ring, or an
aromatic ring, and "nuclear atoms" means the carbon atom(s) and the
nitrogen atom(s) which form a heteroring (inclusive of a saturated
ring, an unsaturated ring and an aromatic ring).
[0030] In formula (I), R.sup.1 to R.sup.4 may be the same or
different and each independently represent hydrogen atom, a
substituted or unsubstituted alkyl group, a substituted or
unsubstituted cycloalkyl group, a substituted or unsubstituted
alkenyl group, a substituted or unsubstituted aryl group, a
substituted or unsubstituted heterocyclic group, a halogen atom, a
substituted or unsubstituted fluoroalkyl group, a substituted or
unsubstituted alkoxyl group, a substituted or unsubstituted
fluoroalkoxyl group, a substituted or unsubstituted aryloxy group,
a substituted or unsubstituted aralkyloxy group, a substituted or
unsubstituted amino group, or cyano group. R.sup.1 and R.sup.2, and
R.sup.3 and R.sup.4 may bond to each other to form a saturated or
unsaturated divalent group which completes a ring.
[0031] Examples of the alkyl group include methyl group, ethyl
group, n-propyl group, isopropyl group, n-butyl group, isobutyl
group, tert-butyl group, and octyl group.
[0032] Examples of the cycloalkyl group include cyclopentyl group
and cyclohexyl group.
[0033] Examples of the alkenyl group include vinyl group, propenyl
group (inclusive of position isomers with respect to double bond),
butenyl group (inclusive of position isomers with respect to double
bond), and pentenyl group (inclusive of position isomers with
respect to double bond).
[0034] Examples of the (substituted) aryl group include phenyl
group, biphenyl group, naphthyl group, fluorophenyl group,
trifluoromethylphenyl group, (trifluoromethyl)fluorophenyl group,
trifluorophenyl group, bis(trifluoromethyl)phenyl group,
(trifluoromethyl)difluorophenyl group, trifluoromethoxyphenyl
group, and trifluoromethoxyfluorophenyl group.
[0035] Examples of the heterocyclic group include the residues of
pyridine, pyrazine, furan, imidazole, benzimidazole, and
thiophene.
[0036] Examples of the halogen atom include fluorine atom, chlorine
atom, bromine atom, and iodine atom.
[0037] Examples of the fluoroalkyl group include trifluoromethyl
group, pentafluoroethyl group, perfluorocyclohexyl group, and
perfluoroadamantyl group.
[0038] Examples of the alkoxyl group include methoxy group and
ethoxy group.
[0039] Examples of the fluoroalkoxyl group include trifluoromethoxy
group, pentafluoroethoxy group, 2,2,2-trifluoroethoxy group,
2,2,3,3,3-pentafluoropropoxy group, 2,2,3,3-tetrafluoropropoxy
group, and 1,1,1,3,3,3-hexafluoropropane-2-yloxy group
[0040] Examples of the (substituted) aryloxy group include
phenyloxy group, pentafluorophenyloxy group, and
4-trifluorophenyloxy group.
[0041] Examples of the (substituted) aralkyloxy group include
benzyloxy group, pentafluorobenzyloxy group, and
4-trifluoromethylbenzyloxy group.
[0042] Examples of the (substituted) amino group include amino
group, mono- or dimethylamino group, mono- or diethylamino group,
and mono- or diphenylamino group.
[0043] The optional substituent of R.sup.1 to R.sup.4 may include
the halogen atom, cyano group, the alkyl group, the aryl group, the
fluoroalkyl group, the fluoroalkoxyl group, and the heterocyclic
group, each mentioned above.
[0044] Unless otherwise noted, the optional substituent referred to
herein by "substituted or unsubstituted" may include the halogen
atom, cyano group, the alkyl group, the aryl group, the fluoroalkyl
group, the fluoroalkoxyl group, and the heterocyclic group, each
mentioned above.
[0045] As mentioned above, R.sup.1 and R.sup.2, and R.sup.3 and
R.sup.4 may bond to each other to form a saturated or unsaturated
divalent group which completes a ring, for example, benzene ring,
naphthalene ring, pyrazine ring, pyridine ring, and furan ring.
[0046] At least one of R.sup.1 to R.sup.4 is preferably fluorine
atom, a fluoroalkyl group, a fluoroalkoxyl group, cyano group, or
an aryl group or heterocyclic group each having at least one group
selected from fluorine, a fluoroalkyl group, a fluoroalkoxyl group,
and cyano group. These substituents can enhance the electron
accepting property, make the sublimation temperature moderate, or
prevent the crystallization.
[0047] In formula (I), ar.sup.1 and ar.sup.2 are may be the same or
different and are independently represented by formula (i) or
(ii):
##STR00006##
[0048] In the above formulae, X.sup.1 and X.sup.2 may be the same
or different and each represent any of the divalent groups (a) to
(g). The groups (a) to (c) are particularly preferred in view of
good heat resistance or easiness of synthesis.
##STR00007##
[0049] In the above formulae, R.sup.21 to R.sup.24 may be the same
or different and each represent hydrogen atom, a substituted or
unsubstituted fluoroalkyl group, a substituted or unsubstituted
alkyl group, a substituted or unsubstituted cycloalkyl group, a
substituted or unsubstituted aryl group, or a substituted or
unsubstituted heterocyclic group. R.sup.22 and R.sup.23 may bond to
each other to form a ring. Examples of the fluoroalkyl group, the
alkyl group, the cycloalkyl group, the aryl group, and the
heterocyclic group are the same as those for R.sup.1 to R.sup.4
mentioned above.
[0050] In formula (I), Y.sup.1 to Y.sup.4 may be the same or
different and each represent --N.dbd., --CH.dbd., or
--C(R.sup.5).dbd., wherein R.sup.5 is defined in the same manner as
R.sup.1 to R.sup.4. The adjacent groups of R.sup.1 to R.sup.5 may
bond to each other to form a saturated or unsaturated divalent
group which completes a ring.
[0051] At least one of Y.sup.1 to Y.sup.4 is preferably nitrogen
atom (the same applies to Y.sup.21 to Y.sup.26 and Y.sup.31 to
Y.sup.38 mentioned below). If at least one of Y.sup.1 to Y.sup.4 is
nitrogen atom, the electron accepting property is enhanced, the
heat resistance is high, or the crystallization is prevented.
[0052] The compounds represented by formulae (iii), (iv), and (v)
are excluded from the compound represented by formula (I).
##STR00008##
[0053] In formulae (iii), (iv), and (v), X.sup.1 and X.sup.2 are as
defined in X.sup.1 and X.sup.2 of formula (I). R.sup.1 to R.sup.4
and R.sup.8 to R.sup.17 are as defined in R.sup.1 to R.sup.4 of
formula (I). Y.sup.5 to Y.sup.14 are as defined in Y.sup.1 to
Y.sup.4 of formula (I).
[0054] The indenofluorenedione derivative of formula (I) is
preferably represented by the following formula (I-A) or (I-B):
##STR00009##
[0055] In formula (I-A), each of Ar.sup.1, etc. is as defined in
the corresponding variable of formula (I). In formula (I-B),
Ar.sup.2 is as defined in Ar.sup.1 of formula (I), X.sup.3 and
X.sup.4 are as defined in X.sup.1 and X.sup.2 of formula (I),
Y.sup.5 to Y.sup.8 are as defined in Y.sup.1 to Y.sup.4 of formula
(I), and R.sup.1 to R.sup.4 are as defined in R.sup.1 to R.sup.4 of
formula (I).
[0056] The indenofluorenedione derivative of formula (I) is more
preferably represented by the following formulae (II) to (VII).
##STR00010## ##STR00011##
[0057] In the above formulae, X.sup.1, X.sup.2, and R.sup.1 to
R.sup.4 are as defined in X.sup.1, X.sup.2, and R.sup.1 to R.sup.4
of formula (I), respectively. Y.sup.21 to Y.sup.26 and Y.sup.31 to
Y.sup.38 are as defined in Y.sup.1 to Y.sup.4 of formula (I).
[0058] The indenofluorenedione derivative of formula (I) is
particularly preferably represented by the following formulae (I-a)
to (I-l). The compounds represented by formulae (I-b), (I-d),
(I-f), (I-h), (I-j), and (I-l) include isomers with respect to the
orientations of the cyano groups in two cyanoimino groups. The
compound of the invention is not limited to a specific isomer.
##STR00012## ##STR00013## ##STR00014##
[0059] In the above formulae, R.sup.31 to R.sup.52 are as defined
in R.sup.1 to R.sup.4 of formula (I). The adjacent groups of
R.sup.31 to R.sup.52 may bond to each other to form a saturated or
unsaturated divalent group which completes a ring. Particularly, at
least one of R.sup.31 to R.sup.52 is preferably fluorine atom, a
fluoroalkyl group, a fluoroalkoxyl group, cyano group, or an aryl
group or heterocyclic group each having at least one group selected
from fluorine, a fluoroalkyl group, a fluoroalkoxyl group, and
cyano group.
[0060] With the structures described above, the indenofluorenedione
derivative of the invention has electron accepting property and
good heat resistance, and further has a sublimation temperature of
about 200.degree. C. or higher to enable the purification by
sublimation, giving a highly pure compound. In addition, an organic
EL device employing the indenofluorenedione derivative can be
driven at a lower voltage and has an improved lifetime. Since the
sublimation temperature is about 200.degree. C. or higher, the
indenofluorenedione derivative does not scatter into a film-forming
apparatus for vapor deposition during the production of devices,
and therefore, does not contaminate the film-forming apparatus and
the organic EL devices being produced. Therefore, the
indenofluorenedione derivative of the invention is suitable as a
material for organic EL devices, particularly, a hole injecting
material.
[0061] Examples of the indenofluorenedione derivative are described
below, although not limited thereto.
##STR00015## ##STR00016## ##STR00017## ##STR00018## ##STR00019##
##STR00020## ##STR00021## ##STR00022## ##STR00023##
[0062] In the production of the indenofluorenedione derivative of
the invention, an indenofluorenedione (I) is first synthesized
according to Scheme 1 with reference to the synthesis methods
described in Chemische Berichte, 1956, vol. 89, p 2799, Journal of
Organic Chemistry, 2001, vol. 66, p 7666, and Japanese Patent
3098330. The indenofluorenedione (I) is converted to a
corresponding dicyanomethylene derivative or cyanoimino derivative
(II) by a method shown in Scheme 2 (details of synthesis
conditions, etc. are found, for example, in Liebigs Ann. Chem.
1986, p 142). The obtained crystals are sublimed for purification
to remove impurities, thereby providing good performance for
improving lifetime, etc. of an organic EL device employing the
resulting compound.
##STR00024##
##STR00025##
[0063] In the above structural formulae, the valuables are as
defined in formula (I).
Material for Organic Electroluminescence Devices
[0064] The material for organic EL devices of the invention
contains at least one kind of the indenofluorenedione derivative of
the invention and has a reduction potential of preferably -1.0 V or
more (vs Fc.sup.+/Fc), more preferably -0.8 V or more (vs
Fc.sup.+/Fc) when measured in an acetonitrile solution, wherein Fc
is ferrocene.
[0065] If the reduction potential is -1.0 V or more, the electron
accepting property is increased. Increased electron accepting
property makes the electron transfer between the material and the
anode made of ITO or other material having a work function lower
than that of ITO easier and makes the HOMO level of a hole
transporting material and the LUMO level of an electron accepting
compound close, thereby making the injection of holes easier.
Organic Electroluminescence Device
[0066] The organic EL device of the invention will be described
below.
[0067] The organic EL device comprises an anode, a cathode and an
organic thin layer between the anode and the cathode. The organic
thin layer contains the material for organic electroluminescence
device of the invention.
[0068] FIG. 1 is a schematic cross-sectional view of an embodiment
of the organic EL devices according to the invention.
[0069] The organic EL device 1 is composed of a substrate (not
shown) and an anode 10, a hole injecting layer 20, a hole
transporting layer 30, a light emitting layer 40, an electron
transporting layer 50, and a cathode 60 which are laminated on the
substrate in this order. The organic thin layer (also referred to
as "organic layer") has a laminated structure composed of the hole
injecting layer 20, the hole transporting layer 30, the light
emitting layer 40, and the electron transporting layer 50. In the
organic EL device having such a layered structure, it is preferred
that at least the hole injecting layer 20 contains the material for
organic EL devices of the invention. With such a structure, the
organic EL device can be driven at lower voltage and a long
lifetime is achieved.
[0070] An organic layer other than the hole injecting layer may
contain the material for organic EL devices of the invention alone
or in combination with the material for each layer which will be
described below.
[0071] The content of the material for organic EL devices in the
hole injecting layer is preferably 1 to 100 mol % and more
preferably 3 to 100 mol %.
[0072] The material for organic EL devices of the invention can be
applied to devices having a layered structure different from that
of the above embodiment. For example, the material for organic EL
devices may be included in each organic layer, such as the light
emitting layer, of the devices having the following layered
structures (1) to (15):
(1) anode/light emitting layer/cathode, (2) anode/hole transporting
layer/light emitting layer/cathode, (3) anode/light emitting
layer/electron transporting layer/cathode, (4) anode/hole
transporting layer/light emitting layer/electron transporting
layer/cathode, (5) anode/hole transporting layer/light emitting
layer/adhesion improving layer/cathode, (6) anode/hole injecting
layer/hole transporting layer/light emitting layer/electron
transporting layer/cathode (FIG. 1), (7) anode/hole transporting
layer/light emitting layer/electron transporting layer/electron
injecting layer/cathode, (8) anode/hole injecting layer/hole
transporting layer/light emitting layer/electron transporting
layer/electron injecting layer/cathode, (9) anode/insulating
layer/hole transporting layer/light emitting layer/electron
transporting layer/cathode, (10) anode/hole transporting
layer/light emitting layer/electron transporting layer/insulating
layer/cathode, (11) anode/inorganic semiconductor layer/insulating
layer/hole transporting layer/light emitting layer/insulating
layer/cathode, (12) anode/insulating layer/hole transporting
layer/light emitting layer/electron transporting layer/insulating
layer/cathode, (13) anode/hole injecting layer/hole transporting
layer/light emitting layer/electron transporting layer/insulating
layer/cathode, (14) anode/insulating layer/hole injecting
layer/hole transporting layer/light emitting layer/electron
transporting layer/electron injecting layer/cathode, and (15)
anode/insulating layer/hole injecting layer/hole transporting
layer/light emitting layer/electron transporting layer/electron
injecting layer/insulating layer/cathode.
[0073] Of the above, preferred are the layered structures (4), (6),
(7), (8), (12), (13), and (15).
[0074] The members for constituting the organic EL device of the
invention will be described below.
Substrate
[0075] The organic EL device of the invention is formed on a
light-transmissive substrate. The light-transmissive substrate
serves as a support for the organic EL device and preferably a flat
substrate having a transmittance of 50% or more to 400 to 700 nm
visible light.
[0076] Examples of the substrate include a plate of glass, such as
soda-lime glass, barium-strontium-containing glass, lead glass,
aluminosilicate glass, borosilicate glass, barium borosilicate
glass, and quartz; and a plate of polymer, such as polycarbonate,
acrylic resin, polyethylene terephthalate, polyether sulfide, and
polysulfone.
[0077] When getting the emitted light from the side opposite to the
substrate, the substrate is not needed to be
light-transmissive.
Anode
[0078] The anode of the organic EL device injects holes to the hole
transporting layer or the light emitting layer. If needed to be
transparent, the anode is made from indium tin oxide alloy (ITO),
tin oxide (NESA), indium zinc oxide alloy (IZO), gold, silver,
platinum, or copper. If a reflective electrode which is not needed
to be transparent is intended, the anode can be made from, in
addition to the materials mentioned above, metal or alloy of
aluminum, molybdenum, chromium and nickel.
[0079] Even when the hole injecting layer comprising the material
for organic EL devices of the invention is combined with an anode
of low work function (for example, 5.0 eV or less), the electron
transfer occurs and the injection property is good.
[0080] The above materials may be used alone. Alloys of the above
materials and the material added with other elements are also
usable.
[0081] The anode is formed by making the electrode material into a
thin film by a vapor deposition method or a sputtering method. When
getting the emitted light from the light emitting layer through the
anode, the transmittance of anode to emitted light is preferably
10% or more. The sheet resistance of anode is preferably several
hundreds .OMEGA./.quadrature. or less. The film thickness of anode
depends upon the kind of material and generally 10 nm to 1 .mu.m,
preferably 10 to 200 nm.
Light Emitting Layer
[0082] The light emitting layer of organic EL device combines the
following functions (1) to (3):
(i) Injection function: allowing holes to be injected from the
anode or hole injecting layer, and allowing electrons to be
injected from the cathode or electron injecting layer, by the
action of electric field; (ii) Transporting function: transporting
the injected charges (holes and electrons) by the force of electric
field; and (iii) Emission function: providing a zone for
recombination of electrons and holes to cause emission.
[0083] The light emitting layer may be different in the hole
injection ability and the electron injection ability, and also may
be different in the hole transporting ability and the electron
transporting ability each being expressed by mobility, although it
is preferred to transport either of hole or electron
dominantly.
[0084] For example, a known process such as a vapor deposition
process, a spin coating process, or LB process is applicable to the
formation of the light emitting layer. The light emitting layer is
particularly preferably a molecular deposit film. The molecular
deposit film is a thin film formed by depositing a vaporized
material or a film formed by solidifying a material in the state of
solution or liquid. The molecular deposit film can be distinguished
from a thin film formed by LB process (molecular build-up film) by
the differences in the assembly structures and higher order
structures and the functional difference due to the structural
differences.
[0085] In addition, the light emitting layer can be also formed by
making a solution of a binder, such as a resin, and its material in
a solvent into a thin film by a spin coating method.
[0086] The light emitting materials usable in the light emitting
layer includes, for example, anthracene, naphthalene, phenanthrene,
pyrene, tetracene, coronene, chrysene, fluorescein, perylene,
phthaloperylene, naphthaloperylene, perinone, phthaloperinone,
naphthaloperinone, diphenylbutadiene, tetraphenylbutadiene,
coumarin, oxadiazole, aldazine, bisbenzoxazoline, bisstyryl,
pyrazine, cyclopentadiene, quinoline metal complex, aminoquinoline
metal complex, benzoquinoline metal complex, imine,
diphenylethylene, vinylanthracene, diaminecarbazol, pyran,
thiopyran, polymethyne, merocyanine, imidazol chelate oxinoid
compound, quinacridone, rubrene and fluorescent dye, although not
limited thereto.
[0087] Examples of the host material for use in the light emitting
layer include the compounds represented by the following formulae
(i) to (ix).
Asymmetric anthracene represented by formula (i):
##STR00026##
wherein Ar.sup.001 is a substituted or unsubstituted condensed
aromatic group having 10 to 50 nuclear carbon atoms; Ar.sup.002 is
a substituted or unsubstituted aromatic group having 6 to 50
nuclear carbon atoms; X.sup.001 to X.sup.003 are each independently
a substituted or unsubstituted aromatic group having 6 to 50
nuclear carbon atoms, a substituted or unsubstituted aromatic
heterocyclic group having 5 to 50 nuclear atoms, a substituted or
unsubstituted alkyl group having 1 to 50 carbon atoms, a
substituted or unsubstituted alkoxy group having 1 to 50 carbon
atoms, a substituted or unsubstituted aralkyl group having 6 to 50
carbon atoms, a substituted or unsubstituted aryloxy group having 5
to 50 nuclear atoms, a substituted or unsubstituted arylthio group
having 5 to 50 nuclear atoms, a substituted or unsubstituted
alkoxycarbonyl group having 1 to 50 carbon atoms, carboxyl group, a
halogen atom, cyano group, nitro group, or hydroxy group; a, b and
c are each an integer of 0 to 4; n is an integer of 1 to 3, and
when n is 2 or more, the anthracene structures in [ ] may be the
same or different. Asymmetric monoanthracene derivative represented
by formula (ii):
##STR00027##
wherein Ar.sup.003 and Ar.sup.004 are each independently a
substituted or unsubstituted aromatic ring group having 6 to 50
nuclear carbon atoms; m and n are each an integer of 1 to 4, with
the proviso that when m=n=1 and the bonding positions of Ar.sup.003
and Ar.sup.004 to the benzene rings are bilaterally symmetric to
each other, Ar.sup.003 is different from Ar.sup.004, and when m or
n is an integer of 2 to 4, m is different from n; and R.sup.001 to
R.sup.010 are each independently hydrogen atom, a substituted or
unsubstituted aromatic ring group having 6 to 50 nuclear carbon
atoms, a substituted or unsubstituted aromatic heterocyclic group
having 5 to 50 nuclear atoms, a substituted or unsubstituted alkyl
group having 1 to 50 carbon atoms, a substituted or unsubstituted
cycloalkyl group, a substituted or unsubstituted alkoxy group
having 1 to 50 carbon atoms, a substituted or unsubstituted aralkyl
group having 6 to 50 carbon atoms, a substituted or unsubstituted
aryloxy group having 5 to 50 nuclear atoms, a substituted or
unsubstituted arylthio group having 5 to 50 nuclear atoms, a
substituted or unsubstituted alkoxycarbonyl group having 1 to 50
carbon atoms, a substituted or unsubstituted silyl group, carboxyl
group, a halogen atom, cyano group, nitro group, or hydroxy group.
Asymmetric pyrene derivative represented by formula (iii):
##STR00028##
wherein Ar.sup.005 and Ar.sup.006 are each a substituted or
unsubstituted aromatic group having 6 to 50 nuclear carbon atoms;
L.sup.001 and L.sup.002 are each a substituted or unsubstituted
phenylene group, a substituted or unsubstituted naphthalenylene
group, a substituted or unsubstituted fluorenylene group, or a
substituted or unsubstituted dibenzosilolylene group; and m is an
integer of 0 to 2, n is an integer of 1 to 4, s is an integer of 0
to 2, and t is an integer of 0 to 4. L.sup.001 and Ar.sup.005 bond
to pyrene at any of 1- to 5-positions, and L.sup.002 and Ar.sup.006
bond to pyrene at any of 6- to 10-positions. Asymmetric anthracene
derivative represented by formula (iv):
##STR00029##
wherein A.sup.001 and A.sup.002 are each independently a
substituted or unsubstituted condensed aromatic ring group having
10 to 20 nuclear carbon atoms; Ar.sup.007 and Ar.sup.008 are each
independently hydrogen atom or a substituted or unsubstituted
aromatic ring group having 6 to 50 nuclear carbon atoms; R.sup.011
to R.sup.020 are each independently hydrogen atom, a substituted or
unsubstituted aromatic ring group having 6 to 50 nuclear carbon
atoms, a substituted or unsubstituted aromatic heterocyclic group
having 5 to 50 nuclear atoms, a substituted or unsubstituted alkyl
group having 1 to 50 carbon atoms, a substituted or unsubstituted
cycloalkyl group, a substituted or unsubstituted alkoxy group
having 1 to 50 carbon atoms, a substituted or unsubstituted aralkyl
group having 6 to 50 carbon atoms, a substituted or unsubstituted
aryloxy group having 5 to 50 nuclear atoms, a substituted or
unsubstituted arylthio group having 5 to 50 nuclear atoms, a
substituted or unsubstituted alkoxycarbonyl group having 1 to 50
carbon atoms, a substituted or unsubstituted silyl group, carboxyl
group, a halogen atom, cyano group, nitro group, or hydroxy group;
and each of Ar.sup.007, Ar.sup.008, R.sup.019 and R.sup.020 may
represent two or more groups and adjacent pair of groups may form a
saturated or unsaturated ring structure, with the proviso that the
groups bonding to 9- and 10-positions of the central anthracene
ring are not bilaterally symmetric with respect to the axis X-Y.
Anthracene derivative represented by formula (v):
##STR00030##
wherein R.sup.021 to R.sup.030 are each independently hydrogen
atom, an alkyl group, a cycloalkyl group, a substituted or
unsubstituted aryl group, an alkoxyl group, an aryloxy group, an
alkylamino group, an alkenyl group, an arylamino group, or a
substituted or unsubstituted heterocyclic group; a and b are each
an integer of 1 to 5, when a and b are 2 or more, R.sup.021 groups
and R.sup.022 groups may be the same or different, respectively,
and R.sup.021 groups and R.sup.022 groups may bond to each other to
form a ring, and R.sup.023 and R.sup.024, R.sup.025 and R.sup.026,
R.sup.027 and R.sup.028, and R.sup.029 and R.sup.030 may bond to
each other to form a ring; L.sup.003 is a single bond, --O--,
--S--, --N(R)-- wherein R is an alkyl group or a substituted or
unsubstituted aryl group, an alkylene group, or an arylene group.
Anthracene derivative represented by formula (vi):
##STR00031##
wherein R.sup.031 to R.sup.040 are each independently hydrogen
atom, an alkyl group, a cycloalkyl group, an aryl group, an alkoxyl
group, an aryloxy group, an alkylamino group, an arylamino group,
or a substituted or unsubstituted heterocyclic group; c, d, e and f
are each an integer of 1 to 5, when c, d, e and f are 2 or more,
R.sup.031 groups, R.sup.032 groups, R.sup.036 groups and R.sup.037
groups may be the same or different, respectively, and R.sup.031
groups, R.sup.032 groups, R.sup.033 groups and R.sup.037 groups may
bond to each other to form a ring, and R.sup.033 and R.sup.034 and
R.sup.038 and R.sup.040 may bond to each other to form a ring; and
L.sup.004 is a single bond, --O--, --S--, --N(R)-- wherein R is an
alkyl group or a substituted or unsubstituted aryl group, an
alkylene group, or an arylene group. Spirofluorene derivative
represented by formula (vii):
##STR00032##
wherein A.sup.005 to A.sup.008 are each independently a substituted
or unsubstituted biphenylyl group or a substituted or unsubstituted
naphthyl group. Condensed ring-containing compound represented by
formula (viii):
##STR00033##
wherein A.sup.001 to A.sup.013 are each independently a substituted
or unsubstituted arylene group having 6 to 50 nuclear carbon atoms;
A.sup.014 to A.sup.016 are each independently hydrogen atom or a
substituted or unsubstituted aryl group having 6 to 50 nuclear
carbon atoms; R.sup.041 to R.sup.043 are each independently
hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a
cycloalkyl group having 3 to 6 carbon atoms, an alkoxyl group
having 1 to 6 carbon atoms, an aryloxy group having 5 to 18 carbon
atoms, an aralkyloxy group having 7 to 18 carbon atoms, an
arylamino group having 5 to 16 carbon atoms, nitro group, cyano
group, an ester group having 1 to 6 carbon atoms, or a halogen
atom; and at least one of A.sup.011 to A.sup.016 is a tri- or more
cyclic condensed aromatic group. Fluorene compound represented by
formula (ix);
##STR00034##
wherein R.sup.051 and R.sup.052 are each hydrogen atom, a
substituted or unsubstituted alkyl group, a substituted or
unsubstituted aralkyl group, a substituted or unsubstituted aryl
group, a substituted or unsubstituted heterocyclic group, a
substituted amino group, cyano group, or a halogen atom; R.sup.051
groups and R.sup.052 groups each bonding to different fluorene
groups may be the same or different; R.sup.051 and R.sup.052
bonding to the same fluorene group may be the same or different;
R.sup.053 and R.sup.054 are each hydrogen atom, a substituted or
unsubstituted alkyl group, a substituted or unsubstituted aralkyl
group, a substituted or unsubstituted aryl group, or a substituted
or unsubstituted heterocyclic group; R.sup.053 groups and R.sup.054
groups each bonding to different fluorene groups may be the same or
different; R.sup.053 and R.sup.054 bonding to the same fluorene
group may be the same or different; Ar.sup.011 and Ar.sup.012 are
each a substituted or unsubstituted condensed polycyclic aromatic
group having 3 or more benzene rings or a substituted or
unsubstituted condensed polyheterocyclic group having a benzene
ring and a hetero ring three or more in total and bonding to the
fluorene group via carbon; Ar.sup.011 and Ar.sup.012 may be the
same or different; and n is an integer of 1 to 10.
[0088] Of the above host materials, preferred are the anthracene
derivatives, more preferred are the monoanthracene derivatives, and
particularly preferred are the asymmetric anthracenes.
[0089] In addition, a phosphorescent compound may be used as the
light emitting material. When the phosphorescent compound is used,
the host material is preferably a compound containing a carbazole
ring. A compound capable of emitting light from triplet exciton is
used as the dopant. The dopant is not particularly limited as long
as it emits light from triplet exciton, and preferably a metal
complex containing at least one metal selected from the group
consisting of Ir, Ru, Pd, Pt, Os and Re, more preferably a
porphyrin metal complex or an orthometalated complex.
[0090] A host suitable for phosphorescence, which comprises a
compound containing a carbazole ring, is a compound capable of
causing the emission of phosphorescent compound by transferring
energy from its excited state to the phosphorescent compound. The
host compound is not limited as long as it is capable of
transferring the exciton energy to the phosphorescent compound and
may be appropriately selected according to the purpose. The host
compound may have any group such as a hetero ring in addition to
the carbazole ring.
[0091] Specific examples of the host compound include a carbazole
derivative, a triazole derivative, an oxazole derivative, an
oxadiazole derivative, an imidazole derivative, a polyarylalkane
derivative, a pyrazoline derivative, a pyrazolone derivative, a
phenylenediamine derivative, an arylamine derivative, an
amino-substituted chalcone derivative, a styrylanthracene
derivative, a fluorenone derivative, a hydrazone derivative, a
stilbene derivative, a silazane derivative, an aromatic tertiary
amine compound, a styrylamine compound, an aromatic dimethylidene
compound, a porphyrin-based compound, an anthraquinodimethane
derivative, an anthrone derivative, a diphenylquinone derivative, a
thiopyran dioxide derivative, a carbodiimide derivative, a
fluorenylidene methane derivative, a distyrylpyrazine derivative, a
heterocyclic tetracarboxylic anhydride such as a
naphthaleneperylene, a phthalocyanine derivative, a metal complex
polysilane compound such as a metal complex of 8-quinolinol
derivative and a metal complex having a ligand such as
metallophthalocyanine, benzoxazole or benzothiazole, an
electrically conductive high-molecular weight oligomer such as a
poly(N-vinylcarbazole) derivative, an aniline copolymer, a
thiophene oligomer and a polythiophene, a high-molecular weight
compound such as a polythiophene derivative, a polyphenylene
derivative, a polyphenylenevinylene derivative and a polyfluorene
derivative. The host compound may be used alone or in combination
of two or more.
[0092] More specific examples are shown below.
##STR00035## ##STR00036##
[0093] The phosphorescent dopant is a compound capable of emitting
light from the triplet exciton. The phosphorescent dopant is not
restricted as long as it emits light from the triplet exciton, and
preferably a metal complex containing at least one metal selected
from the group consisting of Ir, Ru, Pd, Pt, Os and Re, more
preferably a porphyrin metal complex or an orthometalated metal
complex. As the porphyrin metal complex, a porphyrin platinum
complex is preferable. The phosphorescent compound may be used
alone or in combination of two more.
[0094] Various ligands form the orthometalated metal complex, and
preferred examples thereof include 2-phenylpyridine derivatives,
7,8-benzoquinoline derivatives, 2-(2-thienyl)pyridine derivatives,
2-(1-naphthyl)pyridine derivatives, and 2-phenylquinoline
derivatives. These derivatives may be substituted, if necessary. In
particular, a dopant introduced with fluorine atom or
trifluoromethyl group is preferable as the blue-emitting dopant. In
addition, a ligand other than the above ligands such as
acetylacetonate and picric acid may be introduced as a
co-ligand.
[0095] The amount of the phosphorescent dopant in the light
emitting layer may be appropriately selected without particular
limitation, for example, it may be 0.1 to 70% by mass, preferably 1
to 30% by mass. If being 0.1% by mass or more, the light emission
is prevented from being excessively lowered and the effect of using
it is sufficient. If being 70% by mass or less, the concentration
quenching is prevented and consequently the device performance is
prevented from being deteriorated.
[0096] The light emitting layer may contain a hole transporting
material, an electron transporting material or a polymer binder, if
necessary.
[0097] The thickness of the light emitting layer is preferably 5 to
50 nm, more preferably 7 to 50 nm, and most preferably 10 to 50 nm.
If being 5 nm or more, the light emitting layer is easily formed
and the control of color is easy. If being 50 nm or less, the
driving voltage is prevented from increasing.
[0098] The light emitting layer may be included, if necessary, a
known light emitting material other than the compound of the
invention in an amount not adversely affecting the object of the
invention. Alternatively, a light emitting layer containing a known
light emitting material may be laminated on a light emitting layer
containing the compound of the invention.
Hole Transporting Layer and Hole Injecting Layer
[0099] The hole transporting layer is a layer which facilitates the
injection of holes into the light emitting layer and transports
holes to the light emitting region. The layer has a large hole
mobility and an ionization energy generally as small as 5.5 eV or
lower. The hole transporting layer is preferably made from a
material capable of transporting holes to the light emitting layer
at a low electric field strength. The hole mobility of the hole
transporting layer is preferably at least 10.sup.-4 cm.sup.2/Vsec
under an electric field of 10.sup.4 to 10.sup.6 V/cm.
[0100] Examples of the material for the hole transporting layer
include triazole derivative, oxadiazole derivative, imidazole
derivative, polyarylalkane derivative, pyrazoline derivative,
pyrazolone derivative, phenylenediamine derivative, arylamine
derivative, amino-substituted chalcone derivative, oxazole
derivative, styrylanthracene derivative, fluorenone derivative,
hydrazone derivative, stilbene derivative, silazane derivative,
polysilane-based copolymer, aniline-based copolymer, and
electrically conductive high-molecular oligomer (particularly,
thiophene oligomer).
[0101] The hole injecting layer is used to facilitate the injection
of holes. The material for organic EL devices of the invention may
be used as the material for the hole injecting layer alone or in
combination with another material, for example, the materials
mentioned with respect to the hole transporting layer. In addition,
a porphyrin compound, an aromatic tertiary amine compound, and a
styryl amine compound are also usable.
[0102] Also usable are a compound having two fused aromatic rings,
for example, 4,4'-bis(N-(1-naphthyl)-N-phenylamino)biphenyl (NPD),
and a compound having three triphenylamine units connected in star
burst configuration, for example,
4,4',4''-tris(N-(3-methylphenyl)-N-phenylamino)triphenylamine
(MTDATA).
[0103] An aromatic dimethylidene compound, a inorganic compound of
p-type Si, and an inorganic compound of p-type SiC are also usable
as the material for the hole injecting layer.
[0104] The hole injecting layer and the hole transporting layer may
be formed by making the compound mentioned above into a thin film
by a known method, such as a vacuum vapor deposition method, a spin
coating method, a casting method, and LB method. The thickness of
the hole injecting layer and the hole transporting layer is
generally 1 nm to 5 .mu.m, although not particularly limited
thereto.
[0105] The hole injecting, transporting layer may be a single layer
made of one or more kinds of the materials mentioned above or may
be laminated with a different hole injecting, transporting layer,
as long as the hole injecting, transporting layer contains the
compound of the present invention in the hole transporting
region.
[0106] An organic semiconductor layer serves as a part of the hole
transporting layer and assists the injection of holes or electrons
into the light emitting layer. The electrical conductivity thereof
is preferably 10.sup.-10 S/cm or more. Examples of the material for
the organic semiconductor layer include an electrically conductive
oligomer, such as an oligomer having thiophene and an oligomer
having arylamine disclosed in JP 8-193191A, and an electrically
conductive dendrimer, such as a dendrimer having an arylamine.
Electron Injecting/Transporting Layer
[0107] The electron injecting/transporting layer is a layer having
a large electron mobility, which facilitates the injection of
electrons into the light emitting layer and transports them to a
light emitting region.
[0108] The film thickness of the electron transporting layer is
selected from several meters to several micrometers. When the film
thickness is large, the electron mobility is preferably at least
10.sup.-5 cm.sup.2/Vs under an electric field of 10.sup.4 to
10.sup.6 V/cm to avoid the increase of driving voltage.
[0109] As the material for the electron injecting layer, metal
complexes of 8-hydroxyquinoline or derivatives thereof and
oxadiazole derivatives are preferable. Examples of the metal
complexes of 8-hydroxyquinoline and derivatives thereof include
metal chelate oxinoid compounds including chelates of oxine (in
general, 8-quinolinol or 8-hydroxyquinoline), for example,
tris(8-quinolinol)aluminum.
[0110] Examples of the oxadiazole derivatives include an electron
transfer compound represented by the following formulae:
##STR00037##
[0111] In the above formulae, Ar.sup.301, Ar.sup.302, Ar.sup.303,
Ar.sup.305, Ar.sup.306, and Ar.sup.309 each independently represent
a substituted or unsubstituted aryl group. Ar.sup.304, Ar.sup.307,
and Ar.sup.308 each independently represent a substituted or
unsubstituted arylene group.
[0112] Examples of the aryl group include phenyl group, biphenyl
group, anthranyl group, perilenyl group, and pyrenyl group.
Examples of the arylene group include phenylene group, naphthylene
group, biphenylene group, anthranylene group, perilenylene group,
and pyrenylene group. Examples of the substituent include an alkyl
group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10
carbon atoms and cyano group. The electron transporting compound is
preferably a thin-film forming compound.
[0113] Specific examples of the electron transporting compounds
are:
##STR00038##
wherein Me is methyl group and t-Bu is t-butyl group.
[0114] The compounds represented by the following formulae (A) to
(F) may be also used as the material for the electron injecting
layer and the electron transporting layer.
[0115] A nitrogen-containing heteroring derivative represented by
formula (A) or (B):
##STR00039##
wherein A.sup.311 to A.sup.313 each independently represent a
nitrogen atom or a carbon atom; Ar.sup.311 represents a substituted
or unsubstituted aryl group having 6 to 60 nuclear carbon atoms or
a substituted or unsubstituted heteroaryl group having 3 to 60
nuclear carbon atoms; Ar.sup.311' represents a substituted or
unsubstituted arylene group having 6 to 60 nuclear carbon atoms or
a substituted or unsubstituted heteroarylene group having 3 to 60
nuclear atoms; Ar.sup.312 represents a hydrogen atom, a substituted
or unsubstituted aryl group having 6 to 60 nuclear carbon atoms, a
substituted or unsubstituted heteroaryl group having 3 to 60
nuclear atoms, a substituted or unsubstituted alkyl group having 1
to 20 carbon atoms, or a substituted or unsubstituted alkoxy group
having 1 to 20 carbon atoms, with the proviso that at least one of
Ar.sup.311 and Ar.sup.312 is a substituted or unsubstituted
condensed ring group having 10 to 60 nuclear carbon atoms or a
substituted or unsubstituted monohetero condensed ring group having
3 to 60 nuclear atoms.
[0116] L.sup.311, L.sup.312, and L.sup.313 each independently
represents a single bond, a substituted or unsubstituted arylene
group having 6 to 60 nuclear carbon atoms, a substituted or
unsubstituted heteroarylene group having 3 to 60 nuclear atoms, or
a substituted or unsubstituted fluorenylene group.
[0117] R and R.sup.311 each independently represent a hydrogen
atom, a substituted or unsubstituted aryl group having 6 to 60
nuclear carbon atoms, a substituted or unsubstituted heteroaryl
group having 3 to 60 nuclear atoms, a substituted or unsubstituted
alkyl group having 1 to 20 carbon atoms, or a substituted or
unsubstituted alkoxy group having 1 to 20 carbon atoms; n
represents an integer of 0 to 5; when n is 2 or more, R groups may
be the same or different and adjacent R groups may bond to each
other to form an aliphatic ring or an aromatic ring.
[0118] A nitrogen-containing heteroring derivative represented by
formula (C):
HAr-L.sup.314-Ar.sup.321--Ar.sup.322 (C)
wherein HAr represents a nitrogen-containing heterocyclic group
having 3 to 40 carbon atoms which may be substituted; L.sup.314
represents a single bond, an arylene group having 6 to 60 carbon
atoms which may be substituted, a heteroarylene group having 3 to
60 carbon atoms which may be substituted or a fluorenylene group
which may be substituted; Ar.sup.321 represents a divalent aromatic
hydrocarbon group having 6 to 60 carbon atoms which may be
substituted; and Ar.sup.322 represents an aryl group having 6 to 60
carbon atoms which may be substituted or a heteroaryl group having
3 to 60 carbon atoms which may be substituted.
[0119] A silacyclopentadiene derivative represented by formula
(D):
##STR00040##
wherein X.sup.301 and Y.sup.301 each independently represent a
saturated or unsaturated hydrocarbon group having 1 to 6 carbon
atoms, an alkoxy group, an alkenyloxy group, an alkynyloxy group, a
hydroxy group, a substituted or unsubstituted aryl group, or a
substituted or unsubstituted heteroring, or X.sup.301 and Y.sup.301
represent a saturated or unsaturated ring by bonding to each other;
R.sup.301 to R.sup.304 each independently represents a hydrogen
atom, a halogen atom, a substituted or unsubstituted alkyl group,
an alkoxy group, an aryloxy group, a perfluoroalkyl group, a
perfluoroalkoxy group, an amino group, an alkylcarbonyl group, an
arylcarbonyl group, an alkoxycarbonyl group, an aryloxycarbonyl
group, an azo group, an alkylcarbonyloxy group, an arylcarbonyloxy
group, an alkoxycarbonyloxy group, an aryloxycarbonyloxy group, a
sulfinyl group, a sulfonyl group, a sulfanyl group, a silyl group,
a carbamoyl group, an aryl group, a heteroring group, an alkenyl
group, an alkynyl group, a nitro group, a formyl group, a nitroso
group, a formyloxy group, an isocyano group, a cyanate group, an
isocyanate group, a thiocyanate group, an isothiocyanate group, or
a cyano group. These groups may be substituted and adjacent groups
may form a substituted or unsubstituted condensed ring.
[0120] A borane derivative represented by formula (E):
##STR00041##
wherein R.sup.321 to R.sup.328 and Z.sup.322 each independently
represent a hydrogen atom, a saturated or unsaturated hydrocarbon
group, an aromatic hydrocarbon group, a heteroring group, a
substituted amino group, a substituted boryl group, an alkoxy
group, or an aryloxy group; X.sup.302, Y.sup.302 and Z.sup.321 each
independently represent a saturated or unsaturated hydrocarbon
group, an aromatic hydrocarbon group, a heteroring group, a
substituted amino group, an alkoxy group, or an aryloxy group;
Z.sup.321 and Z.sup.322 may bond to each other to form a condensed
ring; n represents an integer of 1 to 3; and when n or (3-n) is 2
or more, R.sup.321 groups to R.sup.328 groups, X.sup.302 groups,
Y.sup.302 groups, Z.sup.322 groups, and Z.sup.321 groups may be the
same or different.
[0121] A gallium complex represented by formula (F):
##STR00042##
wherein Q.sup.301 and Q.sup.302 each independently represent a
ligand represented by the following formula (K), L.sup.315
represents a halogen atom, a substituted or unsubstituted alkyl
group, a substituted or unsubstituted cycloalkyl group, a
substituted or unsubstituted aryl group, a substituted or
unsubstituted heterocyclic group, --OR (wherein R represents a
hydrogen atom, a substituted or unsubstituted alkyl group, a
substituted or unsubstituted cycloalkyl group, a substituted or
unsubstituted aryl group, or a substituted or unsubstituted
heterocyclic group), or a ligand represented by
--O--Ga-Q.sup.303(Q.sup.304) wherein Q.sup.303 and Q.sup.304 are as
defined in Q.sup.301 and Q.sup.302.
##STR00043##
wherein rings A.sup.301 and A.sup.302 each represent a condensed
six-membered aryl ring which may be substituted.
[0122] This metal complex strongly exhibits a character of n-type
semiconductor and has a large electron injection ability. Since the
energy of forming complex is small, the metal and the ligand in
resulting metal complex bond strongly to each other, to increase
the fluorescence quantum efficiency of light emitting material.
[0123] Specific examples of the substituents of rings A.sup.301 and
A.sup.302 each forming the ligand represented by formula (K)
include a halogen atom, such as chlorine, bromine, iodine, and
fluorine; a substituted or unsubstituted alkyl group, such as
methyl group, ethyl group, propyl group, butyl group, s-butyl
group, t-butyl group, pentyl group, hexyl group, heptyl group,
octyl group, stearyl group, and trichloromethyl group; a
substituted or unsubstituted aryl group, such as phenyl group,
naphthyl group, biphenyl group, anthranyl group, phenanthryl group,
fluorenyl group, pyrenyl group, 3-methylphenyl group,
3-methoxyphenyl group, 3-fluorophenyl group,
3-trichloromethylphenyl group, 3-trifluoromethylphenyl group, and
3-nitrophenyl group; a substituted or unsubstituted alkoxyl group,
such as methoxy group, n-butoxy group, t-butoxy group,
trichloromethoxy group, trifluoroethoxy group, pentafluoropropoxy
group, 2,2,3,3-tetrafluoropropoxy group,
1,1,1,3,3,3-hexafluoro-2-propoxy group, and
6-(perfluoroethyl)hexyloxy group; a substituted or unsubstituted
aryloxy group, such as phenoxy group, p-nitrophenoxy group,
p-t-butylphenoxy group, 3-fluorophenoxy group, pentafluorophenyl
group, and 3-trifluoromethylphenoxy group; a substituted or
unsubstituted alkylthio group, such as methylthio group, ethylthio
group, t-butylthio group, hexylthio group, octylthio group, and
trifluoromethylthio group; a substituted or unsubstituted arylthio
group, such as phenylthio group, p-nitrophenylthio group,
p-t-butylphenylthio group, 3-fluorophenylthio group,
pentafluorophenylthio group, and 3-trifluoromethylphenylthio group;
cyano group; nitro group; amino group; a mono- or di-substituted
amino group, such as methylamino group, diethylamino group,
ethylamino group, diethylamino group, dipropylamino group, dibutyl
amino group, and diphenylamino group; an acylamino group, such as
bis(acetoxymethyl)amino group, bis(acetoxyethyl)amino group,
bis(acetoxypropyl)amino group, and bis(acetoxybutyl)amino group;
hydroxyl group; siloxy group; acyl group; a substituted or
unsubstituted carbamoyl group, such as carbamoyl group,
methylcarbamoyl group, dimethylcarbamoyl group, ethylcarbamoyl
group, diethylcarbamoyl group, propylcarbamoyl group,
butylcarbamoyl group, and phenylcarbamoyl group; carboxyl group;
sulfonic acid group; imido group; a cycloalkyl group, such as
cyclopentyl group and cyclohexyl group; and a heterocyclic group,
such as pyridinyl group, pyrazinyl group, pyrimidinyl group,
pyridazinyl group, triazinyl group, indolinyl group, quinolinyl
group, acridinyl group, pyrrolidinyl group, dioxanyl group,
piperidinyl group, morpholidinyl group, piperazinyl group,
carbazolyl group, furanyl group, thiophenyl group, oxazolyl group,
oxadiazolyl group, benzoxazolyl group, thiazolyl group,
thiadiazolyl group, benzothiazolyl group, triazolyl group,
imidazolyl group, and benzimidazolyl group. The above substituents
may bond to each other to form a six-membered aryl ring or
heteroring.
[0124] In a preferred embodiment of the organic EL device, a
reductive dopant is included in an electron transporting region or
an interfacial region between a cathode and an organic layer. The
reductive dopant is defined as a substance capable of reducing an
electron transporting compound. Therefore, various compounds having
a certain level of reducing property may be used as the reductive
dopant. Examples thereof include at least one compound selected
from alkali metals, alkaline earth metals, rare earth metals,
alkali metal oxides, alkali metal halides, alkaline earth metal
oxides, alkaline earth metal halides, rare earth metal oxides, rare
earth metal halides, alkali metal carbonates, alkaline earth metal
carbonates, rare earth metal carbonates, organic complexes of
alkali metals, organic complexes of alkaline earth metals, and
organic complexes of rare earth metals.
[0125] Examples of the preferred reductive dopant include at least
one alkali metal selected from the group consisting of Li (work
function: 2.9 eV), Na (work function: 2.36 eV), K (work function:
2.28 eV), Rb (work function: 2.16 eV), and Cs (work function: 1.95
eV) or at least one alkaline earth metal selected from the group
consisting of Ca (work function: 2.9 eV), Sr (work function: 2.0 to
2.5 eV) and Ba (work function: 2.52 eV). A reductive dopant having
a work function of 2.9 eV or less is particularly preferred.
[0126] Of the above, at least one alkali metal selected from the
group consisting of K, Rb and Cs is more preferred, with Rb and Cs
being still more preferred and Cs being most preferred.
[0127] Since these alkali metals have a particularly high reducing
ability, the luminance and lifetime of the organic EL device are
improved by the addition thereof into an electron injection region
in a relatively small amount. A combination of two or more alkali
metals is also preferably used as the reductive dopant having a
work function of 2.9 eV or smaller. A combination containing Cs,
for example, Cs and Na, Cs and K, Cs and Rb, and Cs, Na and K, is
particularly preferred. By combinedly containing Cs, the reductive
dopant exhibits an effective reducing ability and the luminance and
lifetime of the organic EL device are improved by the addition
thereof into the electron injection region.
[0128] In the organic EL device of the present invention, an
electron injecting layer made of an insulating material or a
semiconductor may be further disposed between the cathode and the
organic layer. The electron injecting layer effectively prevents a
leak of electric current, to improve the electron injection
property.
[0129] The insulating material is preferably at least one metal
compound selected from the group consisting of alkali metal
chalcogenide, alkaline earth metal chalcogenide, alkali metal
halide, and alkaline earth metal halide. When the electron
injecting layer is made of these alkali metal chalcogenides, the
electron injection property is further improved.
[0130] Specific examples of preferred alkali metal chalcogenide
include Li.sub.2O, LiO, Na.sub.2S, Na.sub.2Se, and NaO. Specific
examples of preferred alkaline earth metal chalcogenide include
CaO, BaO, SrO, BeO, BaS, and CaSe. Specific examples of preferred
alkali metal halide include LiF, NaF, KF, CsF, LiCl, KCl, and NaCl.
Specific examples of preferred alkaline earth metal halide include
fluorides, such as CaF.sub.2, BaF.sub.2, SrF.sub.2, MgF.sub.2, and
BeF.sub.2, and halides other than fluorides.
[0131] Examples of the semiconductor for forming the electron
transporting layer include oxides, nitrides and oxynitrides, alone
or in combination of two or more, each containing at least one
element selected from Ba, Ca, Sr, Yb, Al, Ga, In, Li, Na, Cd, Mg,
Si, Ta, Sb, and Zn.
[0132] The electron transporting layer is preferably a crystallitic
or amorphous, insulating thin film of an inorganic compound. Since
the electron transporting layer is made more uniform by forming it
from such an insulating thin film, the pixel defects, such as dark
spots, can be decreased.
[0133] Examples of the inorganic compound include the alkali metal
chalcogenides, the alkaline earth metal chalcogenides, the alkali
metal halides and the alkaline earth metal halides which are
described above.
Cathode
[0134] The cathode is formed from an electrode material, such as
metal, alloy, electrically conductive compound and a mixture
thereof, each having a small work function (4 eV or smaller).
Examples of the electrode material include sodium, sodium-potassium
alloy, magnesium, lithium, magnesium-silver alloy,
aluminum/aluminum oxide, aluminum-lithium alloy, indium, and rare
earth metal.
[0135] The cathode is formed by making the electrode material
described above into a thin film by a process, such as a vapor
deposition process and a sputtering process.
[0136] When the light emitted from the light emitting layer is
taken out of the cathode, the transmittance of the cathode to the
emitted light is preferably 10% or more. The sheet resistivity of
the cathode is preferably several hundreds .OMEGA./.quadrature. or
less and the thickness of the cathode is generally 10 nm to 1 .mu.m
and preferably from 50 to 200 nm.
Insulating Layer
[0137] Since the ultra-thin films of organic EL devices are
affected by the action of electric field, the pixel defects due to
leak and short circuit tends to occur. To prevent the defects, an
insulating thin film layer (insulating layer) is preferably
interposed between the pair of electrodes.
[0138] Examples of the material for the insulating layer include
aluminum oxide, lithium fluoride, lithium oxide, cesium fluoride,
cesium oxide, magnesium oxide, magnesium fluoride, calcium oxide,
calcium fluoride, cesium fluoride, cesium carbonate, aluminum
nitride, titanium oxide, silicon oxide, germanium oxide, silicon
nitride, boron nitride, molybdenum oxide, ruthenium oxide, and
vanadium oxide. These materials may be used in combination or may
be made into laminated layers.
[0139] Production of Organic EL Device
[0140] The organic EL device is produced, for example, by forming
an anode, a hole injecting layer, a hole transporting layer, a
light emitting layer, an electron injecting layer, and other
layers, and then forming a cathode, using the materials mentioned
above. Alternatively, the organic EL device is produced by forming
each layer in a reverse order from the cathode to the anode.
[0141] Example of the production of an organic EL device having a
layered structure of anode/hole injecting layer/hole transporting
layer/light emitting layer/electron transporting layer/cathode on a
light-transmissive substrate will be described below.
[0142] First, on a suitable light-transmissive substrate, an anode
is formed by making the anode material into a thin film having a
thickness of 1 .mu.m or less, preferably 10 to 200 nm by a method,
such as vapor deposition and sputtering.
[0143] Then, a hole injecting layer and a hole transporting layer
are formed on the anode. These layers may be formed by a vacuum
vapor deposition method, a spin coating method, a casting method or
LB method, with the vacuum vapor deposition method being preferred
because a uniform film is easily obtained and pinholes are hardly
formed.
[0144] The conditions of the vacuum vapor deposition method for
forming the hole injecting layer and the hole transporting layer
depend upon the crystalline structure, the recombination structure,
and other factors of the intended hole injecting layer and hole
transporting layer, and the vacuum vapor deposition is conducted
preferably under the conditions: a deposition source temperature of
50 to 450.degree. C., a vacuum degree of 10.sup.-7 to 10.sup.-3
torr, a deposition speed of 0.01 to 50 nm/s, a substrate
temperature of -50 to 300.degree. C., and a film thickness of 1 nm
to 5 .mu.m.
[0145] Then, a light emitting layer is formed on the hole
transporting layer. The light emitting layer is formed by making an
organic light emitting material into a thin film by a vacuum vapor
deposition method, a spin coating method, or a casting method, with
the vacuum vapor deposition method being preferred because a
uniform film is easily obtained and pinholes are hardly formed. The
conditions of the vacuum vapor deposition method for forming the
light emitting layer depend upon the kind of the compound to be
used, and generally selected from those mentioned with respect to
the hole transporting layer.
[0146] Next, an electron transporting layer is formed on the light
emitting layer. Like the formation of the hole transporting layer
and the light emitting layer, the electron transporting layer is
formed preferably by the vacuum vapor deposition method because a
uniform thin film is needed. The conditions of the vacuum vapor
deposition are selected from those mentioned with respect to the
hole transporting layer and the light emitting layer.
[0147] Finally, a cathode is formed on the electron injecting
layer, to obtain an organic EL device.
[0148] The cathode is made of a metal and can be formed by the
vapor deposition method or the sputtering method, with the vacuum
vapor deposition method being preferred in view of preventing the
underlying organic layers from being damaged during the film
forming process.
[0149] In the production of organic EL device mentioned above, the
layers from the anode to the cathode are successively formed
preferably in a single evacuation operation.
[0150] The organic EL device emits light when a voltage is applied
between the electrodes, for example, when a direct voltage of 5 to
40 V is applied with the anode being +terminal and the cathode
being -terminal. If a voltage is applied in the reverse polarity,
no electric current flows and light is not emitted. When an
alternating voltage is applied, the uniform light emission is
observed only in the polarity where the anode is + and the cathode
is -. The wave shape of alternating voltage in not limited.
EXAMPLES
[0151] The present invention will be described in more detail with
reference to the examples. However, it should be noted that the
scope of the invention is not limited thereto.
[0152] The compounds synthesized or used in the following examples
are shown below.
##STR00044##
Example 1
Synthesis of Indenofluorenedione Derivative (A-1)
(1) Synthesis of Intermediate A
[0153] Intermediate A was synthesized according to the following
synthesis scheme:
##STR00045##
[0154] A mixture of 5.0 g of 1,5-diiodo-2,4-dimethylbenzene, 5.8 g
of 4-bromophenylboronic acid, 0.65 g of
tetrakis(triphenylphosphine)palladium(0), 44 ml of 2 M sodium
carbonate, and 40 ml of toluene was refluxed under stirring in
argon stream for 8 h. After cooling, the reaction product solution
was filtered, washed with water and then methanol, and purified on
a silica gel column (developer: methylene chloride), to obtain 4.5
g of white solids. Mass spectrometric measurement of the obtained
white solids showed a peak at M/Z=416.
[0155] Next, a mixture of 4.5 g of the white solids obtained above,
13.0 g of potassium permanganate, 15 ml of pyridine, and 25 ml of
water was heated under stirring at 100.degree. C. for 8 h. After
removing the solid matter by hot filtration, the filtrate was
neutralized by adding a 1 N hydrochloric acid dropwise. The
precipitated white solids separated by filtration was washed with a
diluted hydrochloric acid and then ion exchanged water and dried,
to obtain 2.7 g of white solids.
[0156] The white solids were added to 20 ml of concentrated
sulfuric acid, and the resultant mixture was heated under stirring
at 70.degree. C. for 12 h. The reaction product solution was
allowed to cool and poured into iced water. The orange solids were
collected by filtration, washed with ion exchanged water, and dried
to obtain 2.3 g of solids. Mass spectrometric measurement of the
obtained solids showed a peak at M/Z=440.
[0157] A mixture of 2.3 g of the obtained dibrominated compound,
3.0 g of 4-trifluoromethylphenylboronic acid, 0.24 g of
tetrakis(triphenylphosphine)palladium(0), 25 ml of 2 M sodium
carbonate and 110 ml of toluene was refluxed under stirring in
argon stream for 8 h. After cooling, the reaction product solution
was filtered and washed with water, methanol, and then toluene, to
obtain 2.1 g of orange solids (intermediate A).
[0158] A mass spectrometric measurement of the obtained solids
showed a peak at M/Z=570.
(2) Synthesis of Compound (A-1)
##STR00046##
[0160] A mixture of 1.5 g of the intermediate A, 0.41 g of
malononitrile, and 50 ml of pyridine was heated under stirring at
80.degree. C. for 8 h. After allowing the mixture to cool, the
precipitated solids were collected by filtration, washed with
water, methanol, and then toluene, and vacuum-dried. The dried
solids were purified by sublimation at 350.degree. C., to obtain
1.5 g of purple crystals. Through IR measurement of the obtained
compound, it was found that the absorption at 1730 cm.sup.-1
attributable to carbonyl group disappeared and the absorption
attributable to cyano group appeared at 2222 cm.sup.-1. Mass
spectrometric measurement showed a peak at M/Z=666.
[0161] The obtained compound was measured for the reduction
potential in acetonitrile by cyclic voltammetry using
tetrabutylammonium perchlorate (TBAP) as a supporting electrolyte
and a silver-silver chloride electrode as a reference electrode.
The reduction potential of compound (A-1) was -0.4 Vat a sweeping
speed of 0.1V/s.
[0162] The first oxidation potential of ferrocene (Fc) used as the
standard was 0.5 V when measured in the same manner as above. The
reduction potential of the compound (A-1) on the basis of the
oxidation potential of ferrocene (Fc) was -0.8 V (vs
Fc.sup.+/Fc).
Example 2
Synthesis of Indenofluorenedione Derivative (A-2)
##STR00047##
[0164] In a flask, 2.0 g of the intermediate A synthesized in
Example 1 was dissolved in 100 ml of methylene chloride under
stirring. After replacing the inside of the flask with argon, the
solution was cooled to -10.degree. C. on a sodium chloride/ice
cooling bath. To the solution, 2.7 g of titanium tetrachloride was
added and then a mixed liquid of 8.2 g of
bistrimethylsilylcarbodiimide and 40 ml of methylene chloride was
added dropwise. After the dropwise addition, the solution was
continuously cooled for 1 h, stirred for 4 h at room temperature,
and then refluxed under stirring for 2 h. The precipitated reddish
purple solids were collected by filtration and washed with
methanol.
[0165] Through sublimation at 320.degree. C., 1.2 g of the compound
of the invention was obtained. Through IR measurement of the
obtained compound, it was found that the absorption attributable to
carbonyl group disappeared and the absorption attributable to cyano
group appeared at 2180 cm.sup.-1. Mass spectrometric measurement
showed a peak at M/Z=618.
[0166] The obtained compound was measured for the reduction
potential by cyclic voltammetry in the same manner as in Example 1.
The reduction potential of the compound (A-2) on the basis of the
first oxidation potential of the standard ferrocene (Fc) was -0.95
V (vs Fc.sup.+/Fc).
Example 3
Synthesis of Indenofluorenedione Derivative (A-5)
##STR00048##
[0167] (1) Synthesis of Intermediate B
[0168] In the same manner as in the synthesis of intermediate A in
Example 1 except for using 4.0 g of
3,5-bistrifluoromethylphenylboronic acid in place of 3.0 g of
4-trifluoromethylphenylboronic acid, 2.9 g of the intermediate B
was obtained. The mass spectrometric measurement of the obtained
solids showed a peak at M/Z=706.
(2) Synthesis of Indenofluorenedione Derivative (A-5)
[0169] In the same manner as in the synthesis of compound (A-1) in
Example 1 except for changing 1.5 g intermediate A to 1.8 g of
intermediate B, solids were obtained, which were purified by
sublimation at 340.degree. C., to obtain 1.5 g of dark purple
crystals.
[0170] Through IR measurement of the obtained compound, it was
found that the absorption attributable to carbonyl group
disappeared and the absorption attributable to cyano group appeared
at 2220 cm.sup.-1. Mass spectrometric measurement showed a peak at
M/Z=802.
[0171] The reduction potential of the obtained compound was
measured by cyclic voltammetry in the same manner as in Example 1.
The reduction potential of the compound (A-5) on the basis of the
first oxidation potential of the standard ferrocene (Fc) was -0.88
V (vs Fc.sup.+/Fc).
Example 4
Synthesis of Indenofluorenedione Derivative (A-49)
(1) Synthesis of Intermediate C
[0172] Intermediate C was synthesized according to the following
scheme.
##STR00049##
[0173] In argon atmosphere, 17 g of
1,5-dibromo-2,7-dimethylnaphthalene, 35 g of bispinacolate diboron,
2.8 g of Pd(dppf)Cl.sub.2, 22 g of potassium acetate, and 400 ml of
DMF were charged into a flask. The mixture was heated under
stirring at 80.degree. C. for 65 h. After cooling, the precipitate
was collected by filtration, washed with water and then toluene,
and dried.
[0174] Then, a mixture of 15 g of the obtained boronic ester, 27 g
of bromoiodobenzene, 1.9 g of tetrakis(triphenylphosphine), 26 g of
sodium carbonate, 120 ml of water, and 420 ml of DME in a flask was
heated under stirring in argon atmosphere at 78.degree. C. for 665
h. After cooling, the precipitate was collected by filtration,
washed with water and then methanol, and recrystallized from
toluene.
[0175] Then, a mixture of 13 g of the obtained dibrominated
compound and 120 ml of pyridine in a flask was heated to 95.degree.
C. Thereafter, 10 g of potassium permanganate and 10 ml of ion
exchanged water were added to the mixture. Then, 13 portions of 2 g
of potassium permanganate and 2 ml of water were added to the
mixture every ten minutes. The reaction product solution was
hot-filtered and the filtrate was neutralized by a 2 N hydrochloric
acid. The precipitated white solids were collected by filtration
and washed with water.
[0176] Finally, a mixture of 15 g of the obtained dicarboxylic
compound and 300 ml of a concentrated sulfuric acid in a flask was
heated under stirring at 85.degree. C. for 3 h. After cooling, the
reaction product solution was slowly added to iced water, and the
precipitated solids were collected by filtration and washed with
ion exchanged water. The solids were further purified by
sublimation, to obtain 7 g of the intermediate C. Through IR
measurement of the obtained compound, it was found that the
absorption attributable to carbonyl group appeared at 1720
cm.sup.-1. Mass spectrometric measurement showed a peak at
M/Z=802.
(2) Synthesis of Intermediate D
##STR00050##
[0178] A mixture of 2.7 g of the intermediate C, 4.4 g of
3,5-bis(trifluoromethyl)phenylboronic acid, 0.26 g of
tetrakis(triphenylphosphine)palladium(0), 25 ml of 2 M sodium
carbonate, and 110 ml of toluene was refluxed under stirring in
argon stream for 8 h. After cooling, the reaction product solution
was filtered to collect the solids which were then washed with
water, methanol, and then toluene, to obtain 3.0 g of orange solids
(intermediate D).
[0179] Mass spectrometric measurement on the obtained solids showed
a peak at M/Z=756.
(3) Synthesis of Compound (A-49)
[0180] A mixture of 1.4 g of the intermediate D synthesized above,
0.5 g of malononitrile, and 55 ml of pyridine was heated under
stirring at 110.degree. C. for 8 h. After allowing the mixture to
cool, the solids were collected by filtration, washed with water,
methanol, and then toluene, and vacuum-dried. The solids were then
purified by sublimation at 360.degree. C., to obtain 1.3 g of dark
purple crystals. Through IR measurement of the obtained compound,
it was found that the absorption at 1720 cm.sup.-1 attributable to
carbonyl group disappeared and the absorption attributable to cyano
group appeared at 2220 cm.sup.-1. Mass spectrometric measurement
showed a peak at M/Z=852.
[0181] The obtained compound was measured for the reduction
potential by cyclic voltammetry in the same manner as in Example 1.
The reduction potential of the compound (A-49) on the basis of the
first oxidation potential of the standard ferrocene (Fc) was -0.65
V (vs Fc.sup.+/Fc).
Example 5
Synthesis of Indenofluorenedione Derivative (A-55)
[0182] The synthesis was conducted according to the following
scheme.
##STR00051##
[0183] A mixture of 3.0 g of 1,5-diiodo-2,4-dimethylbenzene, 3.6 g
of 4-trifluoromethoxyphenylboronic acid, 0.39 g of
tetrakis(triphenylphosphine)palladium(0), 26 ml of 2 M sodium
carbonate, and 21 ml of toluene was refluxed under stirring in
argon stream for 8 h. After cooling, the reaction product solution
was filtered, washed with water and then methanol, and purified on
a silica gel column (developer: methylene chloride), to obtain 3.7
g of white solids. Mass spectrometric measurement on the obtained
white solids showed a peak at M/Z=426.
[0184] Then, a mixture of 3.5 g of the white solids, 2.0 g of
potassium permanganate, 13 ml of pyridine, and 25 ml of water was
heated under stirring at 100.degree. C. Thereafter, 1.5-g portions
of potassium permanganate were added to the mixture every 30 min in
total amount of 18 g. After heating under stirring for 8 h from
starting the reaction, the solid matter was removed from the
mixture by hot filtration. The filtrate was neutralized by adding a
1 N hydrochloric acid dropwise. The precipitated white solids were
collected by filtration, washed with a diluted hydrochloric acid
and then ion exchanged water, and dried, to obtain 3.7 g of white
solids.
[0185] Then, a mixture of the white solids and 20 ml of a
concentrated sulfuric acid was heated under stirring at 50.degree.
C. for 12 h. The reaction product solution was allowed to stand for
cooling and poured into iced water. The orange solids were
collected by filtration, washed with ion exchanged water, and
dried, to obtain 3.1 g of solids. Mass spectrometric measurement on
the obtained solids showed a peak at M/Z=450.
[0186] Finally, a mixture of 1.7 g of the diquinone compound thus
synthesized, 1.25 g of malononitrile, and 76 ml of pyridine was
heated under stirring at 50.degree. C. for 8 h. After allowing the
mixture to cool, the solids were collected by filtration, washed
with water, methanol, and then toluene, and vacuum-dried. Then the
solids were purified by sublimation at 280.degree. C., to obtain
1.5 g of purple crystals. Through IR measurement of the obtained
compound, it was found that the absorption at 1730 cm.sup.-1
attributable to carbonyl group disappeared and the absorption
attributable to cyano group appeared at 2222 cm.sup.-1. Mass
spectrometric measurement showed a peak at M/Z=546.
[0187] The obtained compound was measured for the reduction
potential by cyclic voltammetry in the same manner as in Example 1.
The reduction potential of the compound (A-55) on the basis of the
first oxidation potential of the standard ferrocene (Fc) was -0.88
V (vs Fc.sup.+/Fc).
Example 6
Synthesis of Indenofluorenedione Derivative (A-64)
[0188] The synthesis was conducted according to the following
scheme.
##STR00052##
[0189] A mixture of 10 g of 1,5-diiodo-2,4-dimethylbenzene, 5.7 g
of 4-trifluoromethoxyphenylboronic acid, 1.29 g of
tetrakis(triphenylphosphine)palladium(0), 43 ml of 2 M sodium
carbonate, and 70 ml of toluene was refluxed under stirring in
argon stream for 6 h. After cooling, the reaction product solution
was filtered, washed with water and then methanol, and purified on
a silica gel column (developer: hexane), to obtain 3.0 g of white
solids. Mass spectrometric measurement on the obtained white solids
showed a peak at M/Z=392.
[0190] Next, a mixture of 2.9 g of the white solids, 1.8 g of
4-bromophenylboronic acid, 0.35 g of
tetrakis(triphenylphosphine)palladium(0), 17 ml of 2 M sodium
carbonate, and 19 ml of toluene was refluxed under stirring in
argon stream for 6 h. After cooling, the reaction product solution
was filtered, washed with water and then methanol, and purified on
a silica gel column (developer: hexane), to obtain 1.6 g of white
solids. Mass spectrometric measurement on the obtained white solids
showed a peak at M/Z=421.
[0191] Next, a mixture of 1.6 g of white solids, 1.0 g of potassium
permanganate, 6 ml of pyridine, and 10 ml of water was heated under
stirring at 100.degree. C. Thereafter, 1.5-g portions of potassium
permanganate were added to the mixture every 30 min in a total
amount of 13 g. After heating under stirring for 8 h from starting
the reaction, the solid matter was removed by hot filtration and
the filtrate was neutralized by adding a 1 N hydrochloric acid
dropwise. The precipitated white solids collected by filtration was
washed with a diluted hydrochloric acid and then ion exchanged
water and dried, to obtain 1.5 g of white solids.
[0192] Then, a mixture of the white solids and 20 ml of a
concentrated sulfuric acid was heated under stirring at 50.degree.
C. for 12 h. The reaction product solution was allowed to cool and
then poured into iced water. The orange solids were collected by
filtration, washed with ion exchanged water, and dried, to obtain
0.9 g of solids. Mass spectrometric measurement on the obtained
solids showed a peak at M/Z=445.
[0193] A mixture of 0.8 g of the diquinone compound thus obtained,
0.5 g of 4-fluoro-3-trifluoromethylphenylboronic acid, 0.08 g of
tetrakis(triphenylphosphine)palladium(0), 3 ml of 2 M sodium
carbonate, and 4 ml of toluene was refluxed under stirring in argon
stream for 8 h. After cooling, the reaction product solution was
filtered to collect the solids which were washed with water,
methanol, and then toluene, to obtain 0.7 g of range solids
(intermediate A). Mass spectrometric measurement on the obtained
solids showed a peak at M/Z=528.
[0194] Finally, a mixture of 0.7 g of the diquinone compound thus
synthesized, 0.5 g of malononitrile, and 30 ml of pyridine was
heated under stirring at 50.degree. C. for 8 h. After allowing the
mixture to cool, the solids were collected by filtration, washed
with water, methanol, and then toluene, and vacuum-dried. The
solids were then purified by sublimation at 320.degree. C., to
obtain 1.5 g of purple crystals. Through IR measurement of the
obtained compound, it was found that the absorption at 1725
cm.sup.-1 attributable to carbonyl group disappeared and the
absorption attributable to cyano group appeared at 2220 cm.sup.-1.
Mass spectrometric measurement showed a peak at M/Z=624.
[0195] The obtained compound was measured for the reduction
potential by cyclic voltammetry in the same manner as in Example 1.
The reduction potential of the compound (A-3) on the basis of the
first oxidation potential of the standard ferrocene (Fc) was -0.85
V (vs Fc.sup.+/Fc).
Example 7
Synthesis of Indenofluorenedione Derivative (A-23)
[0196] The synthesis was conducted according to the following
scheme.
##STR00053##
[0197] A mixture of 5.0 g of 1,5-diiodo-2,4-dimethylbenzene, 4.1 g
of 4-fluorophenylboronic acid, 0.65 g of
tetrakis(triphenylphosphine)palladium(0), 44 ml of 2 M sodium
carbonate, and 40 ml of toluene was refluxed under stirring in
argon stream for 8 h. After cooling, the reaction product solution
was filtered, washed with water and then methanol, and purified on
a silica gel column (developer: methylene chloride), to obtain 4.0
g of white solids. Mass spectrometric measurement on the obtained
white solids showed a peak at M/Z=294.
[0198] Next, a mixture of 3.4 g of the white solids, 2.0 g of
potassium permanganate, 13 ml of pyridine, and 25 ml of water was
heated under stirring at 100.degree. C. Thereafter, 1.5-g portions
of potassium permanganate were added to the mixture every 30 min in
a total amount of 18 g. After heating under stirring for 8 h from
starting the reaction, the solid matter was removed by hot
filtration and the filtrate was neutralized by adding a 1 N
hydrochloric acid dropwise. The precipitated white solids collected
by filtration were washed with a diluted hydrochloric acid and then
ion exchanged water and dried, to obtain 3.1 g of white solids.
[0199] Then, a mixture of the white solids and 30 ml of a
concentrated sulfuric acid was heated under stirring at 50.degree.
C. for 12 h. The reaction product solution was allowed to cool and
poured into iced water. The orange solids were collected by
filtration, washed with ion exchanged water, and dried, to obtain
2.8 g of solids. Mass spectrometric measurement on the obtained
solids showed a peak at M/Z=318.
[0200] Finally, a mixture of 2.8 g of the diquinone compound thus
synthesized, 2.9 g of malononitrile, and 120 ml of pyridine was
heated under stirring at 50.degree. C. for 8 h. After allowing the
mixture to cool, the solids were collected by filtration, washed
with water, methanol, and then toluene, vacuum-dried, and purified
by sublimation at 300.degree. C., to obtain 2.2 g of purple
crystals. Through IR measurement of the obtained compound, it was
found that the absorption at 1720 cm.sup.-1 attributable to
carbonyl group disappeared and the absorption attributable to cyano
group appeared at 2220 cm.sup.-1. Mass spectrometric measurement
showed a peak at M/Z=414.
[0201] The obtained compound was measured for the reduction
potential by cyclic voltammetry in the same manner as in Example 1.
The reduction potential of the compound (A-3) on the basis of the
first oxidation potential of the standard ferrocene (Fc) was -0.87
V (vs Fc.sup.+/Fc).
Example 8
Organic EL Device
[0202] A glass substrate of 25 mm.times.75 mm.times.1.1 mm
thickness having an ITO transparent electrode (product of Geomatec
Company) was cleaned by ultrasonic cleaning in isopropyl alcohol
for 5 min and then UV ozone cleaning for 30 min.
[0203] The cleaned glass substrate was mounted to a substrate
holder of a vacuum vapor deposition apparatus. The compound (A-1)
synthesized in Example 1 and the compound (C-1) shown below in a
molar ratio of 2:98 were deposited into a film of 60 nm thick so as
to cover the transparent electrode. The film of the mixture worked
as a hole injecting layer.
[0204] Successively, the compound (HTM-1) shown below was made into
a film of 20 nm thick on the mixed film. The obtained film worked
as a hole transporting layer.
[0205] The compound (EM1) and the amine compound (D1) having a
styryl group (light emitting molecule) were deposited into a film
of 40 nm thick in a weight ratio of EM1:D1=40:2. The obtained film
worked as a light emitting layer.
[0206] A 10-nm thick Alq film was further formed on the film thus
formed, which worked as an electron injecting layer. Thereafter, Li
serving as a reductive dopant (Li source: manufactured by SAES
Getters Co., Ltd.) and Alq were co-deposited, to form an Alq:Li
film (10 nm thick) as an electron injecting layer (cathode). Metal
Al is vapor-deposited on the Alq:Li film to form a metal cathode,
thereby obtaining an organic EL device.
##STR00054##
[0207] The organic EL device thus produced was measured for the
driving voltage at a current density of 10 mA/cm.sup.2 and the half
lifetime of light emission when driven by constant DC current at an
initial luminance of 1000 nit at room temperature. The results are
shown in Table 1.
Example 9 to 13
[0208] An organic EL device was produced in the same manner as in
Example 8 except for forming the hole injecting layer into a 10 nm
thick film of each material shown in Table 1 and changing the
thickness of the HTM-1 film (hole transporting layer) to 70 nm. The
results of evaluation are shown in Table 1.
Example 14
[0209] An organic EL device was produced in the same manner as in
Example 8 except for changing the compound (A-1) to the compound
(A-23). The results of evaluation are shown in Table 1.
Comparative Example 1
[0210] An organic EL device was produced in the same manner as in
Example 8 except for forming the hole injecting layer from the
compound (C-1) alone. The results of evaluation are shown in Table
1.
TABLE-US-00001 TABLE 1 Material of hole Driving voltage Half
lifetime injecting layer (V) (h) Examples 8 A-1 6.1 6,900 C-1 9 A-1
6.1 6,800 10 A-5 6.5 6,000 11 A-49 5.9 7,000 12 A-55 5.7 7,100 13
A-64 5.8 7,000 14 A-23 6.0 6,700 C-1 Comparative Example 1 C-1 6.6
5,000
INDUSTRIAL APPLICABILITY
[0211] The indenofluorenedione derivative of the invention is
useful as the material for organic EL devices.
[0212] The material for organic EL devices of the invention is
useful as a material forming the organic EL device, particularly,
as a material for a hole transporting layer and a hole injecting
layer.
[0213] The organic EL device of the invention is suitable as a
light source, such as a backlight of flat emitter and display, a
display of cellular phone, PDA, automotive navigation system, and
automotive instrument panel, and a lighting equipment.
* * * * *