U.S. patent application number 09/768503 was filed with the patent office on 2002-06-27 for organic luminescence device.
Invention is credited to Hashimoto, Yuichi, Senoo, Akihiro, Suzuki, Koichi, Ueno, Kazunori.
Application Number | 20020081454 09/768503 |
Document ID | / |
Family ID | 18545974 |
Filed Date | 2002-06-27 |
United States Patent
Application |
20020081454 |
Kind Code |
A1 |
Suzuki, Koichi ; et
al. |
June 27, 2002 |
Organic luminescence device
Abstract
An organic luminescence device is formed by disposing a layer of
organic compound between a pair of an anode and a cathode. An
organic luminescence device exhibiting orange to red luminescence
at a good durability is provided by including an organic compound
layer containing a spiro compound selected from a specific class,
e.g., one represented by the following structural formula: 1
Inventors: |
Suzuki, Koichi;
(Yokohama-shi, JP) ; Hashimoto, Yuichi; (Toyko,
JP) ; Senoo, Akihiro; (Kawasaki-shi, JP) ;
Ueno, Kazunori; (Ebina-shi, JP) |
Correspondence
Address: |
FITZPATRICK CELLA HARPER & SCINTO
30 ROCKEFELLER PLAZA
NEW YORK
NY
10112
US
|
Family ID: |
18545974 |
Appl. No.: |
09/768503 |
Filed: |
January 25, 2001 |
Current U.S.
Class: |
428/690 ; 257/40;
313/504; 313/506; 428/448; 428/917 |
Current CPC
Class: |
H01L 51/5012 20130101;
C09K 11/06 20130101; H01L 51/0094 20130101; H01L 51/0036 20130101;
Y10S 428/917 20130101 |
Class at
Publication: |
428/690 ;
428/917; 428/448; 313/504; 313/506; 257/40 |
International
Class: |
H05B 033/12 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 27, 2000 |
JP |
019241/2000 |
Claims
What is claimed is:
1. An organic luminescence device, comprising: a pair of electrodes
comprising an anode and a cathode, and a layer of organic compound
disposed between the electrodes; wherein the organic compound layer
contains at least one species of spiro compounds represented by
formulae [I], [II] and [III] shown below: 31wherein R.sub.1,
R.sub.2, R.sub.3 and R.sub.4 independently denote a hydrogen atom,
an alkyl group, a substituted or unsubstituted aralkyl group, a
substituted or unsubstituted aryl group, a substituted or
unsubstituted heterocyclic group or a nitro group; Y denotes --O--,
--S--, 32or --CH.dbd.CH-- wherein R.sub.5 denotes a hydrogen atom,
an alkyl group, a substituted or unsubstituted aralkyl group, a
substituted or unsubstituted aryl group, or a substituted or
unsubstituted heterocyclic group; and X.sub.1 and X.sub.2
independently denote a hydrogen atom, an alkyl group, a substituted
or unsubstituted aralkyl group, a substituted or unsubstituted aryl
group, a substituted or unsubstituted heterocyclic group, a nitro
group, a substituted or unsubstituted amino group, or a group
selected from those represented by structural formulae (IV)-(XIII)
shown below with the proviso that at least one of X.sub.1 and
X.sub.2 is selected from groups represented by the formulae
(IV)-(XIII): 33wherein R.sub.6 to R.sub.14 independently denote a
hydrogen atom, an alkyl group, a substituted or unsubstituted
aralkyl group, a substituted or unsubstituted aryl group, a
substituted or unsubstituted heterocyclic group, an alkoxyl group,
or a nitro group; Z.sub.1 and Z.sub.2 independently denote --S--,
34 35wherein R.sub.15 denotes a hydrogen atom, an alkyl group, a
substituted or unsubstituted aralkyl group, a substituted or
unsubstituted aryl group or a substituted or unsubstituted
heterocyclic group; R.sub.16 and R.sub.17 independently denote an
alkyl group, a substituted or unsubstituted aralkyl group, a
substituted or unsubstituted aryl group or a substituted or
unsubstituted heterocyclic group; and L denotes an integer of 0-20,
m denotes an integer of 0-20 with the proviso that L+m makes an
integer of 1-20, and n is an integer of 1-20.
2. An organic luminescence device according to claim 1, wherein the
organic compound layer contains a spiro compound selected from
those represented by the formulae [I] to [III] wherein both X.sub.1
and X.sub.2 are groups selected from those of the formulae (IV) to
(XIII).
3. An organic luminescence device according to claim 1, wherein the
organic compound layer contains a spiro compound selected from
those represented by the formulae [I] to [III] wherein both X.sub.1
and X.sub.2 are groups selected from those of the formulae (IV) to
(XIII) wherein L+m and n are integers of 2-8.
4. An organic luminescence device according to claim 1, wherein the
organic compound layer comprises laminated layers including an
electron-transporting layer and a luminescence layer, at least oe
of which contains at least one species of the spiro compounds
represented by the formulae [I] to [III].
Description
FIELD OF THE INVENTION AND RELATED ART
[0001] The present invention relates to an organic
(electro-)luminescence device and particularly to an organic
luminescence device for emitting light by applying an electric
field to a film of an organic compound (organic compound
layer).
[0002] An organic luminescence device generally comprises a pair of
electrodes (comprising an anode and a cathode) and a film
comprising a fluorescent organic compound disposed between the
electrodes. Into the organic compound layer (film), holes and
electrons are injected from the anode and the cathode,
respectively, thus forming excitons of the fluorescent organic
compound. When the excitons are returned to ground state, the
organic luminescence device emits light or causes luminescence.
[0003] According to a study by Eastman Kodak Co. ("Appl. Phys.
Lett.", vol. 51, pp. 913-(1987)), it has been reported that a
function-separation type organic luminescence layer comprising
mutually laminated two layers including a layer of an aluminum
quinolinol complex (as an electron transporting and luminescent
material) and a layer of a triphenylamine derivative (as a hole
transporting material) causes luminescence at a luminance
(brightness) of ca. 1,000 cd/m.sup.2 under application of a voltage
of ca. 10 volts. This is also reported in, e.g., U.S. Pat. Nos.
4,539,507; 4,720,432 and 4,885,211.
[0004] Further, by changing species of the fluorescent organic
compound, it is possible to effect luminescence over broad
wavelength regions ranging from an ultraviolet region to an
infrared region. In this regard, various compounds have been
extensively studied in recent years. Such compounds have been
proposed in, e.g., U.S. Pat. Nos. 5,151,629, 5,409,783 and
5,382,477, and Japanese Laid-Open Patent Applications (JP-A)
2-247278, JP-A 3-255190, JP-A 5-202356, JP-A 9-202878 and JP-A
9-227576.
[0005] In addition to the above-mentioned organic luminescence
devices using low-molecular weight materials, an organic
luminescence device using a conjugated polymer has been reported by
a research group of Cambridge University ("Nature", vol. 347, pp.
539-(1990)). According to this report, a signal layer of
polyphenylenevinylene (PPV) is formed through a wet-coating process
and luminescence from the single layer is confirmed. Such an
organic luminescence device using a conjugated polymer has also
been proposed by, e.g., U.S. Pat. Nos. 5,247,190, 5,514,878 and
5,672,678, JP-A 4-145192, and JP-A 5-247460.
[0006] As described above, recent progress in organic luminescence
device is noticeable, and the resultant organic luminescence
devices are characterized by high luminance (brightness) under
application of a low voltage, various (light-)emission wavelengths,
high-speed responsiveness, small thickness and light weight, thus
suggesting possibility of wide applications.
[0007] However, the above-described organic luminescence devices
are still required to effect light output (emission) at a higher
luminance and/or a higher conversion efficiency in the present
state. These organic luminescence devices are also still
insufficient in terms of durability such that the devices are
liable to be changed in their properties with time when used for a
long period or liable to be deteriorated by the influence of
ambient air containing oxygen or of humidity. Further, in the case
of using the organic luminescence devices for full-color display,
it is necessary to effect luminescences of blue, green and red with
good color purities. However, a satisfactory solution to the
problem has not been realized yet, and particularly a red
luminescence with a good color purity has not been satisfactorily
provided.
[0008] On the other hand, spiro compounds having a unique
three-dimensional structure and unique material properties have
been noted as an organic functional material (J. Am. Chem. Soc.
110, p. 5687-(1988)). A proposal of using a spiro compound in an
organic luminescence device has been reported (JP-A 7-278537) but
has failed to provide an electron-transporting layer or a
luminescence layer exhibiting sufficient luminescence
performance.
SUMMARY OF THE INVENTION
[0009] A generic object of the present invention is to provide
improvements to problems an mentioned above encountered in organic
luminescence devices proposed heretofore.
[0010] A more specific object of the present invention is to
provide an organic (electro-) luminescence device capable of
effecting light output (emission) at high efficiency and luminance
while realizing a prolonged life.
[0011] Another object of the present invention is to provide an
organic luminescence device capable of providing a wide variety of
emission wavelengths and emission hues, inclusive of particularly
orange and red hues, and a good durability.
[0012] A further object of the present invention is to provide an
organic luminescence device which can be produced easily and
relatively inexpensively.
[0013] According to the present invention, there is provided an
organic luminescence device, comprising: a pair of electrodes
comprising an anode and a cathode, and a layer of organic compound
disposed between the electrodes; wherein the organic compound layer
contains at least one species of spiro compounds represented by
formulae [I], [II] and [III] shown below: 2
[0014] wherein R.sub.1, R.sub.2, R.sub.3 and R.sub.4 independently
denote a hydrogen atom, an alkyl group, a substituted or
unsubstituted aralkyl group, a substituted or unsubstituted aryl
group, a substituted or unsubstituted heterocyclic grbup or a nitro
group;
[0015] Y denotes --O--, --S--, 3
[0016] or --CH.dbd.CH-- wherein R.sub.5 denotes a hydrogen atom, an
alkyl group, a substituted or unsubstituted aralkyl group, a
substituted or unsubstituted aryl group, or a substituted or
unsubstituted heterocyclic group; and
[0017] X.sub.1 and X.sub.2 independently denote a hydrogen atom, an
alkyl group, a substituted or unsubstituted aralkyl group, a
substituted or unsubstituted aryl group, a substituted or
unsubstituted heterocyclic group, a nitro group, a substituted or
unsubstituted amino group, or a group selected from those
represented by structural formulae (IV)-(XIII) shown below with the
proviso that at least one of X.sub.1 and X.sub.2 is selected from
groups represented by the formulae (IV)-(XIII): 4
[0018] wherein R.sub.6 to R.sub.14 independently denote a hydrogen
atom, an alkyl group, a substituted or unsubstituted aralkyl group,
a substituted or unsubstituted aryl group, a substituted or
unsubstituted heterocyclic group, an alkoxyl group, or a nitro
group;
[0019] Z.sub.1 and Z.sub.2 independently denote --S--, 5
[0020] or 6
[0021] wherein R.sub.15 denotes a hydrogen atom, an alkyl group, a
substituted or unsubstituted aralkyl group, a substituted or
unsubstituted aryl group or a substituted or unsubstituted
heterocyclic group; R.sub.16 and R.sub.17 independently denote an
alkyl group, a substituted or unsubstituted aralkyl group, a
substituted or unsubstituted aryl group or a substituted or
unsubstituted heterocyclic group; and
[0022] L denotes an integer of 0-20, m denotes an integer of 0-20
with the proviso that L+m makes an integer of 1-20, and n is an
integer of 1-20.
[0023] By using the spiro compound represented by the
above-mentioned formula [I], [II] or [III] in the organic
luminescence device, it becomes possible to effect luminescence at
a very high luminance under application of a lower voltage and
provide an excellent durability.
[0024] Particularly, the organic compound layer comprising the
spiro compound of the formula [I], [II] or [III] used in the
present invention is useful as an electron-transporting layer, and
also as a luminscence layer.
[0025] Further, the organic compound layer can be prepared through
vacuum deposition, casting, wet-coating, etc., thus readily
realizing a larger size thereof relatively inexpensively.
[0026] These and other objects, features and advantages of the
present invention will become more apparent upon a consideration of
the following description of the preferred embodiments of the
present invention taken in conjunction with the accompanying
drawing.
BRIEF DESCRIPTION OF THE DRAWING
[0027] FIGS. 1 to 3 are schematic sectional views each illustrating
a basic structure of an organic luminescence device according to an
embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0028] The organic luminescence device according to the present
invention is characterized in that the organic compound layer
disposed between the pair of electrodes (anode and cathode)
contains at least one species of spiro compounds represented by the
above-mentioned formulae [I] to [III].
[0029] Specific examples of the substituents represented by
R.sub.1-R.sub.17 and X.sub.1 and X.sub.2 in the above-mentioned
formulae [I] to [III] and formulae (IV) to (XIII) are enumerated
hereinbelow.
[0030] Specific examples of the alkyl group may include: methyl,
ethyl, n-propyl, iso-propyl, n-butyl, tert-butyl, and octyl.
[0031] Specific examples of the aralkyl group may include: benzyl
and phenethyl.
[0032] Specific examples of the aryl group may include: phenyl,
biphenyl, terphenyl, naphthyl, anthryl and phenanthryl.
[0033] Specific examples of heterocyclic group may include:
thienyl, pyrrolyl, imidazolyl, furyl, pyridyl, indolyl, quinolinyl,
and carbazolyl.
[0034] Specific examples of the amino group may include:
dimethylamino, diethylamino, dibenzylamino, and diphenylamino.
[0035] Specific examples of the alkoxyl group may include:
methoxyl, ethoxyl, propoxyl, and phenoxyl.
[0036] Specific examples of the substituents which may be possessed
by the above-mentioned substituents may include: alkyl groups, such
as methyl, ethyl and propyl; aralkyl groups, such as benzyl and
phenethyl; aryl groups, such as phenyl, nephthyl and anthryl;
heterocyclic groups, such as thienyl, pyrrolyl, pyridyl and
quinolinyl; and amino groups, such as dimethylamino, diethylamino,
dibenzylamino and diphenylamino.
[0037] In view of the easiness of production and capability of
providing a longer luminescent wavelength, it is preferred to use a
spiro compound of the formula [I], [II] or [III] wherein both
X.sub.1 and X.sub.2 are groups represented by any of the
above-mentioned structural formulae (IV)-(XIII) and including a
thiophene skeleton.
[0038] It is also preferred that L+m and n in the structural
formulae (IV)-(XIII) are integers of 2-8.
[0039] It is preferred that the spiro compound of the formula [I],
[II] or [III] is contained in a single luminescence layer
constituting the organic compound layer, or more preferably in a
luminescence layer and/or an electron-transporting layer
constituting the organic compound layer of a laminated structure
for achieving better luminescence performances in a longer
wavelength region.
[0040] Specific examples of the spiro compounds of the formulae
[I]. [II] and [III] are enumerated hereinafter separately for the
respective formulae wherein some representative structures for the
groups X.sub.1 and X.sub.2 are identified by symbols A-1 to A-45
(i.e., Example groups A-1 to A-45) shown below.
[0041] Incidentally, the spiro compounds used in the present
invention inclusive of those enumerated below are synthesized by,
e.g., a method as reported by James M, Tour; Journal of Organic
Chemistry, Vol. 61, pp. 6906-(1996).
[0042] [Structural Examples for the Groups X.sub.1 and X.sub.2]
7
[0043] [Compound Examples] 8
[0044] Specific examples (Compounds Nos. I-1 to I-24) represented
by Formula [I] above wherein substituent positions are indicated by
numbers, are enumerated hereinbelow in Table 1 listing the examples
of groups for R.sub.1-R.sub.4 and X.sub.1 and X.sub.2.
1TABLE 1 Compound No. R.sub.1 R.sub.2 R.sub.3 R.sub.4 X.sub.1
X.sub.2 I-1 H H H H --CH.sub.3 A-3 I-2 H H H H 9 A-5 I-3 H H H H 10
A-15 1-4 H H H H A-2 A-2 1-5 H H H H A-3 A-3 1-6 H H H H A-4 A-4
1-7 H H H H A-6 A-6 1-8 H H H H A-7 A-7 I-9 H H H H A-11 A-11 I-10
4-CH.sub.3 5-CH.sub.3 4'-CH.sub.3 5'-CH.sub.3 A-14 A1-4 I-11 H H H
H A-17 A-17 1-12 H H H H A-23 A-23 1-13 H H H H A-25 A-25 1-14 H H
H H A-32 A-32 1-15 H H H H A-34 A-34 1-16 H H H H A-35 A-35 1-17 H
H H H A-38 A-38 I-18 H H H H A-40 A-40 I-19 H H H H A-42 A-42 I-20
H H H H A-43 A-43 I-21 H H H H A-45 A-45 I-22 11 12 13 14 A-1 A-4
I-23 H H H H A-2 A-14 I-24 H H H H A-30 A-41
[0045] 15
[0046] Specific examples (Compounds Nos. II-1 to II-30) represented
by Formula [II] above, are enumerated in Table 2 below listing the
examples of groups for X.sub.1 and X.sub.2.
2TABLE Compound No. Y X.sub.1 X.sub.2 II-1 --O-- 16 A-5 II-2 --O--
A-3 A-3 II-3 --O-- A-8 A-8 II-4 --O-- A-14 A-14 II-5 --O-- A-25
A-25 II-6 --O-- A-32 A-32 II-7 --O-- A-42 A-42 II-8 --S-- A-1 A-1
II-9 --S-- A-2 A-2 II-10 --S-- A-7 A-7 II-11 --S-- A-11 A-11 II-12
--S-- A-15 A-15 II-13 --S-- A-25 A-25 II-14 --S-- A-27 A-27 II-15
--S-- A-32 A-32 II-16 --S-- A-36 A-36 II-17 --S-- A-38 A-38 II-18
--S-- A-44 A-44 II-19 --S-- A-1 A-5 II-20 --S-- A-2 A-6 II-21 17
A-4 A-4 II-22 18 A-12 A-12 II-23 19 A-15 A-15 II-24 20 A-22 A-22
II-25 21 A-41 A-41 II-26 22 A-45 A-45 II-27 --CH.dbd.CH-- A-3 A-3
II-28 --CH.dbd.CH-- A-16 A-16 II-29 --CH.dbd.CH-- A-27 A-27 II-30
--CH.dbd.CH-- A-43 A-43
[0047] 23
[0048] Specific examples (Compounds Nos. III-1 to III-24)
represented by Formula [III] above wherein substituent positions
ate indicated by numbers, ate enumerated hereinbelow in Table 3
listing the examples of groups for R.sub.1-R.sub.4 and X.sub.1 and
X.sub.2.
3TABLE 3 Compound No. R.sub.1 R.sub.2 R.sub.3 R.sub.4 Y X.sub.1
X.sub.2 III H H H H --O-- --NO.sub.2 A-5 -1 III H H H H --O-- A-7
A-7 -2 III H H H H --S-- A-2 A-2 -3 III H H H H --S-- A-10 A-10 -4
III H H H H --S-- A-21 A-21 -5 III H H H H --S-- A-38 A-38 -6 III H
H H H H A-14 A-14 -7 --N-- III H H H H H A-26 A-26 -8 --N-- III H H
H H CH.sub.3 A-32 A-32 -9 --N-- III 3-CH.sub.3 6-CH.sub.3
3'-CH.sub.3 6'-CH.sub.3 --CH.dbd.CH-- A-28 A-28 -10
[0049] In the organic luminescence device of the present invention,
the organic compound layer comprising the above-mentioned Spiro
compound of the formula [I], [II] or [III] may be formed between
the pair of anode and cathode (electrodes) by vacuum deposition or
wet-coating process. The organic compound layer may preferably be
formed in a thickness of at most 10 .mu.m, more preferably at most
0.5 .mu.m, further preferably 0.01-0.5 .mu.m.
[0050] The organic compound layer constituting the organic
luminescence device of the present invention may have a
single-layer structure as shown in FIG. 1 or a laminate structure
of two or more layers as shown in FIGS. 2 and 3.
[0051] More specifically, FIG. 1 is a schematic sectional view
illustrating an embodiment of the organic luminescence device of
the present invention. Referring to FIG. 1, the organic
luminescence device includes a substrate 1, and an anode 2, a
luminescence layer 3 and a cathode disposed in this order on the
substrate 1 so as to form a laminate structure. The luminescence
layer 3 may comprise a single species of luminescent material
exhibiting a hole-transporting function, an electron-transporting
function and a luminescence function in combination or a mixture of
plural compounds exhibiting these functions, respectively. The
luminescence layer 3 may have a thickness of 5 nm to 1 .mu.m,
preferably 10-500 nm.
[0052] FIG. 2 is a sectional view showing a laminate structure of
another embodiment of the organic luminescence device. Referring to
FIG. 2, the organic luminescence device includes a substrate 1, and
an anode 2, a hole-transporting layer 5, an electron-transporting
layer 6 and a cathode 4 disposed successively in this order on the
substrate 1 so as to form a laminate structure, either one or both
of the hole-transporting layer 5 and the electron-transporting
layer 6 may contain a luminescent material also having a
hole-transporting function and/or an electron-transporting
function, respectively, for constituting a luminescence layer 3 in
combination. One of the layers 6 and 5 may contain a material
having no luminescent function but having a good
electron-transporting or hole-transporting function. Each of the
hole-transporting layer 5 and the electron-transporting layer 6 may
have a thickness of 5 nm to 1 .mu.m, preferably 10-500 nm.
[0053] FIG. 3 is a sectional view showing still another embodiment
of the organic luminescence device of the present invention.
Referring to FIG. 3, the organic luminescence device includes a
substrate 1, and an anode 2, a hole-transporting layer 5, a
luminescence layer 3, an electron-transporting layer 6 and a
cathode 4 disposed successively in this order on the substrate 1 to
form a laminate structure. In this embodiment, the carrier
transporting functions and the luminescent function of the organic
compound layer are separated and assigned to the respective layers.
Each of the hole-transporting layer 5, the luminescence layer 3 and
the electron-transporting layer 6 may contain a single species or
plural species of compounds showing respectively expected functions
so as to exhibit desired performances. More specifically, in the
case of using plural species of compounds in combination, a lot of
latitude is provided in selection of materials for each layer, and
various compounds having different emission wavelengths can be used
to provide a variety of luminescence hues.
[0054] Further, as the carriers and excitons are effectively
confined in the central luminescence layer 3, it is possible to
increase the luminescence efficiency.
[0055] In the embodiment of FIG. 3, each of the hole-transporting
layer 5, the luminescence layer 3 and the electron-transporting
layer 6 may have a thickness of 5 nm-1 .mu.m, preferably 10-500
nm.
[0056] It is to be understood however that FIGS. 1 -3 described
above merely show basic structures of the organic luminescence
device according to the present invention, and various
modifications thereof are possible. For example, between the
organic compound layer(s) and the electrodes (anode and cathode),
it is possible to dispose an electron injection layer (on the
cathode side), a hole injection layer (on the anode side), an
insulating layer, an adhesive layer, or an interference layer.
Further, the hole-transporting layer 5 can be divided into two
layers with different ionization potentials.
[0057] The Spiro compound represented by the formula [I], [II] or
[III] have better electron-transporting performance, luminescence
performance and durability than conventional compounds and can be
adopted in any of the device structures shown in FIGS. 1 to 3.
[0058] The organic compound layer containing the spiro compound is
particularly useful as an electron-transporting layer and/or a
luminescence layer. A layer thereof may be formed by vacuum
deposition or solution coating in a form which is not liable to
crystallize and is excellent in stability with time.
[0059] In the present invention, the spiro compound of the formula
[I], [II] or [III] can be used to constitute an
electron-transporting layer and/or a luminescence layer, as
desired, in combination with a known hole-transporting compound,
luminescent compound or electron-transporting compound, examples of
which are enumerated hereinbelow. 24 25 26 27 28
[0060] As mentioned above, the organic compound layer containing
the Spiro compound of the formula [I], [II] or [III] or other
organic compound layers may be formed into film by vacuum
deposition or coating of a solution of the relevant compound in an
appropriate solvent. In the case of the solution coating, the
organic compound can be used in mixture with an appropriate binder
resin to form a film. In this case, the organic compound, inclusive
of the spiro compound of the formula [I], [II] or [III], may for
example be used in 0.1-10 wt. parts per 100 wt. parts of the binder
resin.
[0061] The binder resin used for the above purpose may be selected
from a wide variety of scope. Examples thereof may include:
polyvinyl carbazole resin, polycarbonate resin, polyester resin,
polyarylate resin, polystyrene resin, acrylic resin, methacrylic
resin, butyral resin, polyvinyl acetal resin, diallyl phthalate
resin, phenolic resin, epoxy resin, silicone resin, polysulfone
resin, and urea resin. These resins may be used singly or in
combination of two or more species or in the form of
copolymers.
[0062] As a material for the anode (2 shown in FIGS. 1-3), it is
preferred to use one having as large a work function as possible,
examples of which may include: metals, such as gold, platinum,
nickel, palladium, cobalt, selenium and vanadium, and their alloys;
metal oxides, such as tin oxide, zinc oxide, indium tin oxide
(ITO), and indium zinc oxide; and electroconductive polymers, such
as polyaniline, polypyrrole, polythiophene, and polyphenylene
sulfide. These compounds may be used singly or in combination of
two or more species.
[0063] On the other hand, as a material for the cathode 4 shown in
FIGS. 1-3, it is preferred to use one having a small work function,
examples of which may include: metals, such as lithium, sodium,
potassium, calcium, magnesium, aluminum, indium, silver, lead, tin
and chromium, and their alloys. It is also possible to use metal
oxide, such as indium tin oxide (ITO). The cathode may be formed in
a single layer or a lamination of plural layers.
[0064] The substrate 1 shown in FIGS. 1-3 for the organic
luminescence device of the present invention may include an opaque
substrate of metal, ceramics, etc., and a transparent substrate of
glass, quartz, plastics, etc. It is possible to form the substrate
with a color filter film, a fluorescent color conversion film, a
dielectric reflection film, etc., thus controlling emitted
luminescent light.
[0065] In order to prevent contact with oxygen and/or moisture, the
organic luminescence device of the present invention may further
include a protective layer or a sealing layer. Examples of the
protective layer may include: an inorganic film of diamond, metal
oxide, metal nitride, etc.; a polymer film of fluorine-containing
resin, polyparaxylene, polyethylene, silicone resin, polystyrene,
etc., and a film of light-curable resin. It is also possible to
effect packaging of the organic luminescence device per se with a
sealing resin while covering the organic luminescence device with
glass, gas-impermeable film, metal, etc.
[0066] Hereinbelow, the present invention will be described more
specifically based on Examples.
EXAMPLE 1
[0067] An electroluminescence device of a structure as shown in
FIG. 2 was prepared in the following manner.
[0068] A 1.1 mm-thick glass substrate coated with a 120 nm-thick
film of ITO (indium tin oxide) formed by sputtering was
successively washed with acetone and isopropyl alcohol (IPA) under
application of ultrasonic wave and then washed with IPA under
boiling, followed by cleaning by UV/ozone (i.e., irradiation with
ultraviolet rays in the ozone-containing atmosphere), to obtain a
transparent conductive substrate (including a substrate 1 and an
ITO anode 2 formed thereon).
[0069] The transparent conductive substrate was coated by vacuum
deposition of a compound (TPD) represented by a structural formula
shown below: 29
[0070] to form a 60 nm-thick hole-transporting layer 5 and then by
vacuum deposition of a spiro compound (Compound No. I-5 listed in
Table 1) to form a 60 nm-thick electron-transporting layer 6. The
vacuum deposition was respectively performed in a vacuum of
1.0.times.10.sup.-4 Pa and at a film thickness growth rate of
0.2-0.3 nm/sec.
[0071] Then, the electron-transporting layer was further coated by
vacuum deposition of Al--Li alloy (Li content: 1 atom %) to form a
150 nm-thick metal film 4 under a vacuum of 1.0.times.10.sup.-4 Pa
and at a film thickness growth rate of 1.0-1.2 nm/sec, thereby
forming an organic luminescence device of a structure shown in FIG.
2.
[0072] The thus-obtained device was then supplied with a DC voltage
of 8 volts between the ITO electrode 2 as an anode and the Al--Li
alloy electrode as a cathods, whereby a current flowed at a density
of 8.8 mA/cm.sup.2 and red luminescence was observed at a luminance
of 620 cd/m.sup.2. The device was further subjected to 100 hours of
continuous voltage application at a constant current density of 7.0
mA/cm.sup.2 in a nitrogen atmosphere, whereby the device initially
exhibited a luminance of 550 cd/m.sup.2, which was lowered to 490
cd/m.sup.2 after 100 hours, thus showing only a small luminance
deterioration.
EXAMPLES 2-20
[0073] Organic luminescence devices were prepared and evaluated in
the same manner as in Example 1 except for replacing the spiro
compound of Compound No. I-5 with Compounds Nos. I-2, I-4, I-7,
I-9, I-13, I-17, I-20, I-23, II-1, II-3, II-8, II-9, II-14, II-20,
II-24, III-3, III-4, III-7 and III-10, respectively, listed in
Tables 1 to 3 set forth above.
[0074] The results are inclusively shown in Table 4 set forth
hereinafter.
COMPARATIVE EXAMPLES 1-3
[0075] Comparative organic luminescence devices were prepared and
evaluated in the same manner as in Example 1 except for using
Comparative Compound Nos. 1-3, respectively, shown below, instead
of Compound No. I-5. The results are also shown in Table 4. 30
4 TABLE 4 Luminance Initial (at 7.0 mA/cm.sup.2) Exam- Compound
Voltage Luminance Initial After 100 ple No. (V) (cd/m.sup.2)
(cd/m.sup.2) hrs. (cd/m.sup.2) 1 I-5 8 620 550 490 2 I-2 8 350 310
275 3 I-4 8 590 535 490 4 I-7 8 380 330 285 5 I-9 8 330 295 250 6
I-13 8 580 520 475 7 I-17 8 250 225 190 8 I-20 8 270 230 190 9 I-23
8 350 300 265 10 II-1 8 170 130 105 11 II-3 8 595 540 480 12 II-8 8
225 190 160 13 II-9 8 550 510 475 14 II-14 8 220 170 150 15 II-20 8
560 520 485 16 II-24 8 240 205 170 17 III-3 8 575 520 475 18 III-4
8 250 210 170 19 III-7 8 170 130 110 20 III-10 8 190 155 120 Comp.
Comp. 8 45 40 10 1 No. 1 Comp. Comp. 8 80 55 20 2 No. 2 Comp. Comp.
8 25 20 ** 3 No. 3 **: No luminescence
EXAMPLE 21
[0076] The procedure of Example 1 was repeated up to the formation
of the hole-transporting layer 5.
[0077] Then, the hole-transporting layer 5 was further coated by
vacuum deposition of a mixture of spiro compound (Compound No. I-6)
and aluminum tris(quinolinol) in a weight ratio of 1:20 to form a
60 nm-thick electron-transporting layer 6 under a vacuum of
1.0.times.10.sup.-4 Pa and at a film thickness growth rate of
0.2-0.3 nm/sec.
[0078] Then, the electron-transporting layer was further coated by
vacuum deposition of Al--Li alloy (Li content: 1 atom. %) to form a
150 nm-thick metal film 4 under a vacuum of 1.0.times.10.sup.-4 Pa
and at a film thickness growth rate of 1.0-1.2 nm/sec, thereby
forming an organic luminescence device of a structure shown in FIG.
2.
[0079] The thus-obtained device was then supplied with a DC voltage
of 8 volts between the ITO electrode 2 as an anode and the Al--Li
alloy electrode as a cathods, whereby a current flowed at a density
of 8.3 mA/cm.sup.2 and red luminescence was observed at a luminance
of 530 cd/m.sup.2. The device was further subjected to 100 hours of
continuous voltage application at a constant current density of 7.0
mA/cm.sup.2 in a nitrogen atmosphere, whereby the device initially
exhibited a luminance of 480 cd/m.sup.2, which was lowered to 450
cd/m.sup.2 after 100 hours, thus showing only a small luminance
deterioration.
EXAMPLES 22-29
[0080] Organic luminescence devices were prepared and evaluated in
the same manner as in Example 21 except for replacing the spiro
compound of Compound No. I-6 with Compounds Nos. I-11, I-14, I-19,
I-22, II-6, II-12, II-27 and III-8, respectively, listed in Tables
1 to 3 set forth above.
[0081] The results are inclusively shown in Table 5 set forth
hereinafter.
COMPARATIVE EXAMPLES 4-6
[0082] Comparative organic compound devices were prepared and
evaluated in the same manner as in Example 21 except for using
Comparative Compound Nos. 1-3, respectively, shown above, instead
of Compound No. I-6. The results are also shown in Table 5.
5 TABLE 5 Luminance Initial (at 7.0 mA/cm.sup.2) Exam- Compound
Voltage Luminance Initial After 100 ple No. (V) (cd/m.sup.2)
(cd/m.sup.2) hrs. (cd/m.sup.2) 21 I-6 8 530 480 450 22 I-11 8 660
605 560 23 I-14 8 460 425 385 24 I-19 8 355 320 290 25 I-22 8 595
540 490 26 II-6 8 645 600 560 27 II-12 8 430 390 350 28 II-27 8 570
525 475 29 III-8 8 480 435 390 Comp. Comp. 8 270 230 120 4 No. 1
Comp. Comp. 8 305 250 110 5 No. 2 Comp. Comp. 8 260 230 30 6 No.
3
EXAMPLE 30
[0083] The procedure of Example 1 was repeated up to the formation
of the hole-transporting layer 5.
[0084] Then, the hole-transporting layer 5 was further coated by
vacuum deposition of aluminum tris(quinolinol) to form a 25
nm-thick luminescence layer 3 and then by vacuum deposition of a
spiro compound (Compound No. I-4) to form a 40 nm-thick
electron-transporting layer 6, respectively under a vacuum of
1.0.times.10.sup.-4 Pa and at a film thickness growth rate of
0.2-0.3 nm/sec.
[0085] Then, the electron-transporting layer was further coated by
vacuum deposition of Al--Li alloy (Li content: 1 atom. %) to form a
150 nm-thick metal film 4 under a vacuum of 1.0.times.10.sup.-4 Pa
and at a film thickness growth rate of 1.0-1.2 nm/sec, thereby
forming an organic luminescence device of a structure shown in FIG.
3.
[0086] The thus-obtained device was then supplied with a DC voltage
of 10 volts between the ITO electrode 2 as an anode and the Al--Li
alloy electrode as a cathods, whereby a current flowed at a density
of 11.0 mA/cm.sup.2 and orange luminescence was observed at a
luminance of 1270 cd/m.sup.2. The device was further subjected to
100 hours of continuous voltage application at a constant current
density of 10.0 mA/cm.sup.2 in a nitrogen atmosphere, whereby the
device initially exhibited a luminance of 1100 cd/m.sup.2, which
was lowered to 1010 cd/m.sup.2 after 100 hours, thus showing only a
small luminance deterioration.
EXAMPLES 31-38
[0087] Organic luminescence devices were prepared and evaluated in
the same manner as in Example 30 except for replacing the spiro
compound of Compound No. I-4 with Compounds Nos. I-8, I-12, I-16,
I-21, II-6, II-18, III-1 and III-6, respectively, listed in Tables
1 to 3 set forth above.
[0088] The results are inclusively shown in Table 6 set forth
hereinafter.
COMPARATIVE EXAMPLES 7-9
[0089] Comparative organic luminescence devices were prepared and
evaluated in the same manner as in Example 30 except for using
Comparative Compound Nos. 1-3, respectively, shown above, instead
of Compound No. I-4. The results are also shown in Table 6.
6 TABLE 6 Luminance Initial (at 7.0 mA/cm.sup.2) Exam- Compound
Voltage Luminance Initial After 100 ple No. (V) (cd/m.sup.2)
(cd/m.sup.2) hrs. (cd/m.sup.2) 30 I-4 10 1270 1100 1010 31 I-8 10
950 820 740 32 I-12 10 1330 1190 1100 33 I-16 10 1280 1100 990 34
I-21 10 930 805 740 35 II-6 10 900 790 720 36 II-18 10 640 600 530
37 III-1 10 570 525 460 38 III-6 10 860 805 755 Comp. Comp. 10 130
100 35 7 No. 1 Comp. Comp. 10 160 125 40 8 No. 2 Comp. Comp. 10 55
40 ** 9 No. 3 **: No luminescence.
EXAMPLE 39
[0090] A transparent conductive substrate prepared and treated for
cleaning in the same manner as in Example 1 was coated with a
solution of 0.050 g of a Spiro compound (Compound No. I-5) and 1.00
g of poly-N-vinylcarbazole (weight-average molecular weight=63,000)
in 80 ml of chloroform by spin coating at a rate of 2000 rpm,
followed by drying, to form a 120 nm-thick organic layer
(luminescence layer) 3.
[0091] Then, the luminescence layer was further coated by vacuum
deposition of Al--Li alloy (Li content: 1 atom %) to form a 150
nm-thick metal film 4 under a vacuum of 1.0.times.10.sup.-4 Pa and
at a film thickness growth rate of 1.0-1.2 nm/sec, thereby forming
an organic luminescence device of a structure shown in FIG. 1.
[0092] The thus-obtained device was then supplied with a DC voltage
of 10 volts between the ITO electrode 2 as an anode and the Al--Li
alloy electrode as a cathode, whereby a current flowed at a density
of 8.7 mA/cm.sup.2 and red luminescence was observed at a luminance
of 320 cd/m.sup.2.
COMPARATIVE EXAMPLE 10
[0093] An organic luminescence device was prepared in the same
manner as in Example 39 except for using Comparative Compound No. 2
instead of Comparative Example No. I-5.
[0094] The resultant device was similarly supplied with a DC
voltage of 10 volts, whereby a current followed at a density of 8.1
mA/cm.sup.2 and yellow-green luminescence was observed at a
luminance of 25 cd/m.sup.2.
* * * * *