JPH11283748A - Organic electroluminescent element material, manufacture of organic electroluminescent element material and organic electroluminescent element using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a material that is excellent in reliability and luminous efficiency and has a variety of luminescent colors by using a compound that has a three-rotational symmetry, does not have a two-rotational symmetry and has a cyclic partial structure. SOLUTION: A compound to be used is a compound that preferably has a tribenzo[c, i, o]triphenylene carbon skeleton and is expressed by a formula. In the formula, R1-R3 each represent a hydrogen atom, halogen atom, cyano group, nitro group, alkyl group, alkoxy group, aryloxy group, cycloalkylalkyl group, alkenyloxyalkyl group, cyanoalkyl group, phenyl group, cycloalkyl group or amide group. 1,7,13-trimethyltribenzo[c, i, o]triphenylene or 1,7,13- triphenyltribenzo[c, i, o] triphenylene is suitable. An organic luminescence element using the compound expressed by the formula hardly causes the aggregation of molecules, and allows the energy level of electrons to be brought into a suitable condition, so that its luminous efficiency and service life are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electroluminescence (EL) device utilizing an electroluminescence (EL) phenomenon of an organic substance, and more particularly to a light emitting device which applies an electric field to a laminated thin film made of an organic compound. And a device that emits light.

[0002]

2. Description of the Related Art An organic EL device has a structure in which a thin film containing a fluorescent organic compound is sandwiched between a cathode and an anode. It is an element that generates an excited state such as exciton, and emits light by utilizing light emission (fluorescence, phosphorescence, delayed fluorescence, etc.) when the excited state is deactivated.

[0003] Features of the organic EL device, any are possible surface emission of high luminance of about 100~10000cd / m ² at about 10V low voltage and blue by selecting the kind of the fluorescent substance to red It is possible to emit light in the colors described above.

On the other hand, the problems of the organic EL device are that the device life during continuous light emission is short, storage durability and reliability are low. This is because (1) physical change in the organic compound. This causes non-uniformity of the interface due to the growth of the crystal domain, for example, which causes deterioration of the charge injection capability of the device, short-circuiting and dielectric breakdown. In particular, when a low-molecular compound having a molecular weight of 300 g / mol or less is used, crystal grains may appear or grow, and a phenomenon that the film properties may be significantly reduced may occur. Further, even if the interface of ITO or the like is rough, remarkable crystal grains appear and grow, which causes a decrease in luminous efficiency and a current leak, thereby causing no light emission. Also,
It also causes a partial non-light emitting part (dark spot),
(2) Oxidation and peeling of the cathode, specifically, simple metals such as Li, Mg, and Al and alloys thereof have been used as metals having a small work function to facilitate electron injection. In some cases, these metals react with moisture or oxygen in the atmosphere, or the organic compound layer and the cathode are separated from each other, so that a phenomenon that charge injection cannot be performed may occur. In particular, when a film is formed by spin coating or the like using a polymer compound or the like, a residual solvent or a decomposition product at the time of film formation promotes an oxidation reaction of the electrode, peeling of the electrode occurs, and a partial non-light emitting portion is generated. (3) When the luminous efficiency is low, the calorific value increases, and the heat causes the degradation or destruction of the element due to melting, crystallization, thermal decomposition, etc. of the organic compound, and (4) the organic compound layer Photochemical change or electrochemical change of the polymer.

In particular, in order to solve the above problem (1), low molecular weight amorphous compounds and high molecular weight compounds have been studied.

However, low-molecular compounds can be deposited but have poor heat resistance. In addition, high molecular compounds have heat resistance,
Since vapor deposition cannot be performed, a laminated structure cannot be obtained, and there is a serious problem in the process such as mixing of a residual solvent and impurities due to film formation by spin coating or the like, and significant deterioration of electrodes and organic substances. Therefore, application of an organic compound capable of solving these problems is desired.

On the other hand, recently, for the purpose of improving device performance, various EL devices having a mixed layer in which two or more compounds having different functions are mixed have been proposed.

For example, JP-A-2-250292 discloses a laminated structure of an organic compound having a hole-transporting ability and a light-emitting function and an organic compound having an electron-transporting ability for the purpose of improving luminance and durability. Japanese Patent Application Laid-Open No. 2-291696 discloses that a thin film of
In Japanese Patent Application Laid-Open Publication No. H11-163, it is proposed that a thin film of a mixture of an organic compound having a hole transport function and a fluorescent organic compound having an electron transport ability is used for the light emitting layer.

Further, JP-A-4-178487 and JP-A-5-78655 disclose a thin film layer in which the components of the organic luminescent thin film layer are composed of a mixture of an organic charge transporting material and an organic luminescent material. It has been proposed that the light emitting material can be selected in a wide range by preventing the occurrence of light, and a high-luminance full-color element can be obtained.

Further, rubrene (ie, 5,
6,11,12-Tetraphenylnaphth
acene) has been proposed. The structure of the rubrene molecule is represented by the chemical formula 5 in JP-A-8-231951.
(Corresponding to FIG. 6 (j) in the present application).

The structure of the rubrene molecule has twice rotational symmetry from the viewpoint of neglecting the twist of the phenyl group, but has rotational symmetry other than double rotational symmetry such as triple rotational symmetry. Not.

Here, that a molecule has n-fold rotational symmetry, where n is a natural number of 2 or more, means that a certain straight line is used as an axis of rotation, while maintaining the arrangement between the atoms constituting the molecule and the angle. When rotated by (2π / n) radians,
Before and after rotation, the arrangement of each atom matches, that is, the congruence (co
ngr.). The axis of rotation when the molecule has n-fold rotational symmetry is called the n-fold rotational symmetry axis.

The symmetric axis of the two-fold rotational symmetry of the rubrene molecule includes a two-fold rotational symmetry axis in the direction of the major axis of the naphthacene skeleton on a plane formed by the naphthacene skeleton of the rubrene molecule;
There are two types of axes: a two-fold rotational symmetry axis that is orthogonal to the plane that the naphthacene skeleton constitutes and that passes through the center of gravity of the naphthacene skeleton.
Thus, the structure of the rubrene molecule is characterized by having high symmetry.

The intermolecular attractive force acting between the molecules changes depending on the shape of the molecule, but it is generally known that a stronger intermolecular attractive force acts when the molecules can come close to each other.

It is also known that the higher the symmetry of the molecular structure, the closer the molecules can be approached to each other, and the stronger the intermolecular attractive force tends to act.

Due to the high symmetry of the atomic arrangement of rubrene, a plurality of rubrene molecules can be aggregated in close proximity to each other, so that rubrene easily forms a coherent aggregate. Also, once such aggregates are formed,
It is considered that a strong intermolecular attraction acts between the molecules, and the phenomenon that the aggregate is decomposed and dispersed into a single molecule is unlikely to occur.

As the organic compound layer doped with rubrene, an organic EL device having a hole transport layer composed of a mixed film of hydrazine derivatives and a light emitting layer of tris (8-quinolinolato) aluminum as the organic compound layer,
A hole transport layer doped with rubrene, or a hole transport layer in which half of the organic interface side of the hole transport layer and the entire light emitting layer are doped with rubrene has been proposed.

In the case where the hole transport layer is doped, light emission occurs from both tris (8-quinolinolato) aluminum and rubrene. In the case where the hole transport layer and the light emitting layer are doped, light emission occurs. It has been reported that the efficiency is improved and that the increase of dark spots during storage can be suppressed [Kanai, Yajima, Sato,
Proceedings of the 39th JSAP Lecture Meeting, 28p
-Q-8 (1992): Sato, Kanai, Workshop on Organic Electronics Materials (JOEM) Workshop 92, 31 (1992)].

Further, a triphenyldiamine derivative (TP
A device which emits yellow light in which the hole transport layer of D) is doped with rubrene has been proposed, and it has been reported that the luminance half-life is greatly improved [Fujii, Sano, Fujita, Hamada, Shibata, 59th edition] Proceedings of the Conference of JSAP, 29p
-ZC-7 (1993)].

Japanese Patent Application Laid-Open No. 2-207488 proposes a device provided with a p-type inorganic semiconductor thin film layer and an organic compound thin film layer comprising a layer mainly composed of rubrene. It is described that stability of emission luminance can be obtained.

However, none of these EL devices is completely satisfactory in terms of the life of the device during continuous light emission and the heat resistance.

The inventor of the present invention has found that, in these EL devices using rubrene, the property that rubrene is apt to form aggregates has an adverse effect. In particular, in a device in which rubrene is doped into another charge transporting material, It was thought that rubrene was not necessarily dispersed in the charge transport material to a single molecular state, and that rubrene did not provide sufficient properties due to the presence of rubrene aggregates. . Then, the inventors proceeded with a study on the possibility that an EL element having excellent characteristics could be obtained by designing a molecule while paying attention to the symmetry of the molecule.

In general, the symmetry of a molecule not only affects the strength of the intermolecular force acting between the molecules, but also affects the energy level of the electrons contained in the molecule. As a result, the symmetry of the molecule is closely related to the emission spectrum of the molecule. It is known that there is. Therefore, if the symmetry of the molecule is extremely increased or decreased, an appropriate emission color may not be obtained. Therefore, when designing a molecule, it is necessary to give the molecule an appropriate symmetry.

JP-A-5-70773 and JP-A-9-1997
176630 discloses an element doped with a quinacridone compound as a light emitting material. The general structure of the molecule of the quinacridone compound is described in JP-A-9-1766.
It is shown in Chemical Formula 1 of Japanese Patent Publication No. 30.

The structure of the quinacridone compound has two-fold rotational symmetry from the viewpoint of the skeleton structure ignoring the arrangement of substituents, but has a higher rotational symmetry such as three-fold rotational symmetry. I haven't. As the symmetry axis of the two-fold rotational symmetry of the skeleton of the quinacridone compound, there is only one kind of the two-fold rotational symmetry axis that passes through the center of gravity of the quinacridone compound and is orthogonal to the plane that is formed by the aromatic ring including the center of gravity. And also in an EL element using a quinacridone compound,
As disclosed in Example 6 of JP-A-9-176630, in a light-emitting element doped with unsubstituted quinacridone at a concentration of 0.80%, the initial luminous efficiency is 8.3c.
d / A, and the luminance half time in AC driving from the initial luminance of 1657 cd / m ² is only about 400 hours. In general, it is known that the luminance half-life is shorter when performing DC current driving than AC current driving, so when performing DC current driving in the above example, the luminance half-life is even shorter than 400 hours. This is not satisfactory in terms of improving the life of the element during continuous light emission and improving the luminous efficiency.

Further, in Example 11 of JP-A-8-231951, an element doped with decacyclene as a light emitting material is disclosed. The structure of the dekacyclene molecule is
This is shown in Chemical Formula 6 of JP-A-8-231951.

The structure of the decacyclene molecule has a two-fold rotational symmetry and a three-fold rotational symmetry, but has a higher rotational symmetry such as a four-fold rotational symmetry. Not. As the symmetry axes of the two-fold rotational symmetry of the decacyclene molecule, there are three types of two-fold rotational symmetry axes passing through the center of gravity of the decacyclene molecule and each of the centers of gravity of the three naphthalene substituents. In addition, the axis of symmetry of the two-fold rotational symmetry of the decacyclene molecule is one kind of two-axis orthogonal to the plane formed by the center benzene ring passing through the center of gravity of the decacyclene molecule.
Only the axis of rotational symmetry exists.

As described above, the dekacyclene molecule is characterized by having a very high symmetry. Due to the high symmetry of the atomic arrangement of decacyclene, a plurality of decacyclene molecules can be closely aggregated similarly to the case of the rubrene molecule, and it is considered that the decacyclene has a property of easily forming a coherent aggregate.

Then, an EL element using decacyclene is used.
Also, in Example 11 of JP-A-8-231951,
Luminous efficiency in the initial state, as disclosed in
Is 8.0 lumens per watt (lm / W)
, Initial luminance 500 cd / m ^TwoDC constant current drive from
Has a luminance half-life of about 900 hours,
In terms of device life and luminous efficiency
Not something.

Further, JP-A-5-331458, elements doped fullerenes C ₆₀ such as a light emitting material is disclosed. The structure of the C ₆₀ molecule is icosahedral and has two-fold, three-fold, five-fold, and six-fold rotational symmetries. I do not have. The axes of symmetry of the two-fold and three-fold rotational symmetries of the C ₆₀ molecule are identical to the axes of the six-fold rotational symmetry.

There are four types of six-fold rotational symmetry axes passing through the center of gravity of the C ₆₀ molecule and each of the centers of gravity of the eight six-membered rings formed by carbon. Furthermore, 5-fold rotational symmetry axis of the C ₆₀ molecules, and the center of gravity of the C ₆₀ molecules, carbon constitutes 12
There are six types that pass through each of the centers of gravity of each of the five five-membered rings.

As described above, the C ₆₀ molecule is characterized by having extremely high symmetry. In addition, fullerenes include C
Higher fullerenes, such as ₇₀ molecules, are included.
Chiba et al., Mat. Res. Symp. Pro
c. 359, 3 (1995); Achiba
"The Chemical Physics F
ullerene 10 (and 5) years
Later, "ed. By W. Andreoni, Kl
lower Academic Printed (199
6), p. 139 ", all known fullerenes have the property of always having a two-fold rotational symmetry axis (C2 rotational symmetry axis).

[0033] Then, as disclosed in JP-A 5-331458 discloses a mixture of C ₆₀ and C ₇₀ (C ₆₀ 8
(0%) at a molar concentration of 0.80%, the initial luminous efficiency is 1.01 at a luminance of 100 cd / m ² .
48 lm / W, and the luminance half-life is not disclosed. It is said that the voltage rise after 50 hours in DC constant current driving at a current density of 5 mA / cm ² is 1 V or less, and the brightness decrease is not a practical problem. It is estimated to be before and after. Therefore, EL using fullerene such as C ₆₀
Also in the element, it is not satisfactory in terms of the life of the element at the time of continuous light emission and improvement of luminous efficiency.

As described above, various compounds having a two-fold rotational symmetry and / or a three-fold rotational symmetry have been studied, but they are satisfactory in terms of improvement of the lifetime and luminous efficiency of the device during continuous light emission. Not something you can do.

[0035]

SUMMARY OF THE INVENTION It is an object of the present invention to use, as a charge transporting material or a light emitting material, an organic material having an optoelectronic function with little physical change, photochemical change and electrochemical change, and to improve reliability and light emission. An object of the present invention is to realize an EL element using organic materials having various luminescent colors with high efficiency. In particular, using an organic thin film formed by vapor deposition of a compound with a relatively high molecular weight, high reliability and high luminance by suppressing voltage rise and current leakage during operation of the device, and the appearance and growth of partial non-light emitting portions It is to realize an organic light emitting device.

It is still another object of the present invention to provide an organic light-emitting device in which the life of the device during continuous light emission is improved, and in particular, a decrease in luminance during driving over a long period of time is suppressed.

[0037]

The above objects can be attained by the present invention of the following (1) to (14). (1) The material for an organic light-emitting device according to claim 1 of the present invention comprises at least one compound having a cyclic partial structure, and the compound having the cyclic partial structure has three-fold rotational symmetry; It is characterized by having a structure that does not have two-fold rotational symmetry. (2) The material for an organic light-emitting device according to claim 2 of the present invention, wherein the compound having a cyclic partial structure comprises a skeleton structure having aromaticity at least in part thereof and a substituent bonded to the skeleton structure; The skeletal structure is characterized by having a structure having three-fold rotational symmetry and not having two-fold rotational symmetry. (3) The compound of claim 3 of the present invention is characterized in that it has a planar skeleton structure in its partial structure. (4) The compound of claim 4 of the present invention is characterized by having a triphenylene carbon skeleton in its partial structure. (5) In the material for an organic light-emitting device according to claim 5 of the present invention, the compound having a cyclic partial structure is tribenzo [c,
[i, o] triphenylene carbon skeleton in its partial structure. For example, it contains at least one or more compounds having the structure shown in FIG. 5 (e) [in the chemical formula shown in FIG. 5 (e),
The substituents R1 to R3 may be the same or different,
A hydrogen atom; a halogen atom such as a fluorine atom and a chlorine atom; a hydroxyl group; a cyano group; a nitro group; an alkyl group having an arbitrary number of carbon atoms such as a methyl group and an ethyl group; an alkoxy group such as a methoxy group and an ethoxy group; Alkoxyalkyl groups such as ethoxyethyl group; aryloxy groups such as phenyloxy group and naphthyloxy group; aryloxyalkyl groups such as phenyloxyethyl group, naphthyloxyethyl group and p-chlorophenyloxyethyl group; benzyl group and phenethyl group And arylalkyl groups such as p-chlorobenzyl group and p-nitrobenzyl group; cycloalkylalkyl groups such as cyclohexylmethyl group, cyclohexylethyl group and cyclopentylethyl group; allyloxyethyl group and 3-bromoallyloxyethyl group Alkenyloxyalkyl A cyanoalkyl group such as a cyanoethyl group or a cyanomethyl group; a hydroxyalkyl group such as a hydroxyethyl group or a hydroxymethyl group; a substituted or unsubstituted alkyl group such as a tetrahydrofurylalkyl group such as a tetrahydrofuryl group or a tetrahydrofurylethyl group A substituted or unsubstituted alkenyl group such as a 2-chloroallyl group; a phenyl group, a p-methylphenyl group,
Substituted or unsubstituted aryl groups such as naphthyl group and m-methoxyphenyl group; cycloalkyl groups such as cyclohexyl group and cyclobentyl group; alkoxycarbonyl groups such as methoxycarbonyl group and ethoxycarbonyl group; acyl groups; siloxy groups; A substituted or unsubstituted amino group; a substituted or unsubstituted amide group; a substituted or unsubstituted aromatic hydrocarbon ring; a substituted or unsubstituted aromatic heterocycle. ]. The number and position of the substituents are arbitrary. (6) The compound according to claim 6 of the present invention comprises tribenzo [c,
i, o] having a triphenylene carbon skeleton in its partial structure, wherein the 1-position, the 7-position,
A substituent other than a hydrogen atom is bonded to the 13-position. That is, it is characterized by containing at least one or more compounds having the structure shown in FIG. 5 (e), and in the chemical formula shown in FIG.
1 to R3 are substituents other than a hydrogen atom, and may be the same or different. (7) The compound of claim 7 of the present invention is characterized in that it is 1,7,13-trimethyltribenzo [c, i, o] triphenylene. (8) The compound according to claim 8 of the present invention comprises 1,7,13-triphenyltribenzo [c, i, o] triphenylene,
Or a derivative thereof. (9) The compound of claim 9 of the present invention is 1,7,13-tris (1,1′-biphenyl-4-yl) tribenzo [c, i, o] triphenylene or a derivative thereof. And (10) The compound of claim 10 of the present invention is 1,3,5-
Tris (ortho-methylstyryl) benzene or a derivative thereof. (11) The compound according to claim 11 of the present invention comprises: benzyltriphenylphosphonium bromide or a derivative thereof;
A step of generating 1,3,5-tristyrylbenzene or a derivative thereof by a carbon-carbon bond formation reaction with 3,5-triformylbenzene. (12) The compound according to claim 12 of the present invention is 1,3,5-
By the photocyclization reaction of tris styrylbenzene or a derivative thereof, tribenzo [c, i, o] triphenylene,
Or a step of producing a derivative thereof. (13) An organic light-emitting device according to claim 13 of the present invention, wherein the light-emitting layer contains the material for an organic light-emitting device according to any one of claims 1 to 10 and a derivative of an aromatic amine. It is characterized by being. (14) An organic light-emitting device according to a fourteenth aspect of the present invention is that the light-emitting layer contains the material for an organic light-emitting device according to any one of the first to tenth aspects and a metal complex. Features.

[0038]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, specific embodiments of the present invention will be described together with comparative examples, and the present invention will be described in more detail. <First Embodiment> 1,7,13-trimethyltribenzo
[C, i, o] triphenylene (FIG. 4 (a)
As a first step, a mixture of 50 mmol of 2-methylbenzyltriphenylphosphonium bromide (see FIG. 4D) and 80 cm ^{3 of} tetrahydrofuran (THF) from which water had been removed was cooled to −78 ° C. , Butyl lithium 45mm
ol was added and stirred for 15 minutes, 15 mmol of 1,3,5-triformylbenzene (see FIG. 4 (c)) dispersed in 20 cm ³ of THF was added, and the mixture was stirred at 30 ° C. for 5 hours. Thus, a first reaction product mixture was obtained.

The first reaction product mixture is purified by removing the impurities by adsorption through a silica gel column, eluting with a normal hexane solvent containing 1% by volume of ethyl acetate, and recrystallizing from a normal hexane solution. ,
2.6 g of 1,3,5-tris (ortho-methylstyryl) benzene (see FIG. 4 (b)) was obtained at a yield of 50%. Figure 4
The compound of (b) is a mixture of the Z-isomer and the E-isomer in geometrical isomerism, which is a configuration around a double bond.

Next, as a second step, 1 g (2.3 mmol) of the compound shown in FIG. 4 (b) is dissolved in cyclohexane from which water has been removed, and dissolved through nitrogen gas to remove the existing oxygen. Then, a small amount of iodine was added as a catalyst, and photoirradiation was caused by irradiating light with a medium pressure mercury lamp for 90 minutes to obtain a second reaction product mixture.

The second reaction product mixture is purified by removing impurities by adsorption through a silica gel column, eluting with a normal hexane solvent containing 1% by volume of ethyl acetate, and recrystallizing from a normal hexane solution. Then, 80 mg of the compound shown in FIG. 4 (a) was obtained in a yield of 8%. <Second embodiment> 1,7,13-triphenyltribenzo
Synthesis of [c, i, o] triphenylene As a first step, instead of 50 mmol of 2-methylbenzyltriphenylphosphonium bromide (see FIG. 4 (d)) in the first embodiment, FIG. Substituents R1 to R3 in the chemical formula of FIG. 5 (f) were the same as in the first embodiment except that 50 mmol of 2-phenylbenzyltriphenylphosphonium bromide in which the substituent R in the chemical formula was a phenyl group was used. 1, a phenyl group
3,5-Tris (ortho-phenylstyryl) benzene was obtained in a yield of 45%. The compound shown in FIG. 5 (f) is a mixture of the Z-isomer and the E-isomer in geometrical isomerism in the configuration around the double bond.

Next, as a second stage, instead of 2.3 mmol of the compound of FIG. 4B in the first embodiment,
In the same manner as in the first embodiment except that 2.3 mmol of 1,3,5-tris (ortho-phenylstyryl) benzene in which the substituents R1 to R3 in the chemical formula of FIG. Then, 1,7,13-triphenyltribenzo [c, i, o] triphenylene in which the substituents R1 to R3 in the chemical formula of FIG. 5E were phenyl groups was obtained at a yield of about 7%. <Third Embodiment> 1,7,13-tris (1,1′-biphenyl)
-4-yl) tribenzo [c, i, o] trip
Synthesis of henylene As the first step, 2-methylbenzyltriphenylphosphonium bromide in the first example (see FIG. 4 (d))
2- (1,1′-biphenyl-4-yl) benzyl bromide in which the substituent R in the chemical formula of FIG. 5 (g) is replaced by (1,1′-biphenyl-4-yl) group instead of 50 mmol Except that 50 mmol of triphenylphosphonium was used, the substituents R1 to R3 in the chemical formula of FIG. 5 (f) were replaced with (1,1′-biphenyl-4) in the same manner as in the first example.
-Yl) -based 1,3,5-tris-ortho-
(1,1′-biphenyl-4-yl) styryl @ benzene was obtained in a yield of 35%. The compound shown in FIG. 5 (f) is a mixture of the Z-isomer and the E-isomer in geometrical isomerism in the configuration around the double bond.

Next, as a second step, the substituents R1 to R3 in the chemical formula of FIG. 5F are replaced with (1, 1) instead of the compound 2.3 mmol of FIG. 4B in the first embodiment. '-Biphenyl-4-yl) group,
3,5-tris-ortho- (1,1′-biphenyl-4
-Yl) styryl｝ benzene in the same manner as in the first embodiment except that 2.3 mmol was used, and the substituents R1 to R3 in the chemical formula of FIG. 5E were replaced with 1,1′-biphenyl-.
1,7,13-tris (1,1′-
Biphenyl-4-yl) tribenzo [c, i, o] triphenylene was obtained in a yield of about 6%. <Fourth Embodiment> Next, 1,7,13-trimethyltribenzo [c, i, o] triphenylene (FIG. 4A)
To produce an organic light-emitting device which is used by doping the compound with an aromatic amine derivative.

FIG. 1 is a sectional view of an organic light emitting device according to a fourth embodiment of the present invention.

As a first step, a plurality of transparent electrodes 2 are formed on a glass substrate 1 in a band shape (in a direction perpendicular to the plane of FIG. 1).
Are patterned in parallel with each other. The film thickness of the transparent electrode 2 at this time is d. d is, for example, 200 nm (8
It can be changed in the range of 0 nm to 3 μm, and preferably in the range of 100 nm to 1 μm).

When the transparent electrode 2 is used as an anode, indium tin oxide (ITO), tin oxide (SnO)
₂ ) A conductive material having a large work function such as gold (Au) can be used.

When gold is used as the electrode material, the electrode becomes translucent. In this embodiment, the transparent electrode 2 was formed using indium tin oxide (ITO).
As the patterning method, a known method can be used in addition to a wet etching method using an aqueous hydrochloric acid solution containing FeCl ₃ .

Next, as a second step, the transparent electrode 2 is cleaned by ultraviolet irradiation in an atmosphere containing oxygen until a clean surface of the transparent electrode 2 appears. Here, in the above-mentioned cleaning, the temperature of the glass substrate 1 is set to 60 ° C. (can be changed in a range of 0 ° C. to 200 ° C., and preferably in a range of 40 ° C. to 110 ° C.), and pure oxygen is supplied at a flow rate of 40 ° C. Wavelength using two low-pressure mercury lamps of 300 W input power as light sources in an oxygen atmosphere containing ozone (O ₃ ) obtained by supplying a surface discharge type ozone generator at a constant flow rate of 3 liters per minute. 185
The irradiation was performed by irradiating ultraviolet rays having main peak components at nm and 254 nm.

The time required until a clean surface of the transparent electrode 2 appeared was about 10 minutes. At this time, the distance between the tube wall of the lamp and the uppermost part of the substrate surface was 5 mm, but the distance is arbitrary as long as ultraviolet light of sufficient intensity can be obtained on the substrate surface.

At this time, the ozone concentration in the vicinity of the insulator layer 8 was 9.8 g / m ^3. However, if the ozone concentration is 0.01 g / m ³ or more, the ozone concentration adheres to the surface of the transparent electrode 2 by adding ozone. Or the effect of promoting the oxidative decomposition of the adsorbed impurities can be expected, preferably at a concentration of 0.1 g / m ³ or more, more preferably at a concentration of 1 g / m ³ or more, and particularly preferably at a concentration of 5 g / m ^3. m ³ or more is sufficient.

Subsequently, after forming an organic electroluminescent layer 7 on the transparent electrode 2 as a third step, a back electrode 6 crosses the transparent electrode 2 on the organic electroluminescent layer 7 as a fourth step. It is formed by a vacuum evaporation method. Here, the back electrode 6 has a layer thickness of 100 nm (50 nm to 500 n).
m) and an alloy in which Mg and In are co-evaporated at a weight ratio of 9: 1 (In content is 0.1 wt.
It can be changed in the range of 01% to 99%, preferably in the range of 1% to 75%, and more preferably in the range of 5% to 25%.

As necessary, a protective film 8 is formed to cover the organic electroluminescent layer 7 and the back electrode 6 as a fifth step. The protective film 8 is made of silicon oxide (SiO) having a thickness of 15
A material formed by a vacuum vapor deposition method so as to have a thickness of 0 nm (the thickness can be changed within a range of 50 nm to 500 nm, and an arbitrary layer thickness may be used when another material is used). An insulating material having low property can be used.

The protective film 8 is provided for the purpose of suppressing a phenomenon that the back electrode 6 and the organic electroluminescent layer 7 are deteriorated by moisture, oxygen, or the like, and may be omitted.

Next, a method of forming the organic electroluminescent layer 7 composed of three layers will be described as a third step.

On the transparent electrode 2, an organic hole injecting and transporting layer 3, a light emitting layer 4, and an organic electron injecting and transporting layer 5 are formed in this order by a vacuum evaporation method. The organic hole injecting and transporting layer 3 is a derivative of the aromatic amine shown in FIG. 6 (h) having a layer thickness of 35 nm (can be changed in the range of 10 nm to 80 nm), and 4,4 ′, 4 ″ -tris (3-methylph).
(enylphenylamino) triphenyl
Amine (commonly known as MTDATA). MTDAT
The molar mass of the molecule of A is 753 g / mol.

The light emitting layer 4 is composed of N, N'-Diphenyl-N, N 'which is a derivative of the aromatic amine shown in FIG.
-(3-methylphenyl) -1,1'-b
iphenyl-4,4'-diamine (commonly known as TP
D) as the main component and 1,7,13-trimethyltribenzo [c, i, o] triphenylene (see FIG. 4 (a))
Can be changed in a weight ratio of 3% (in the range of 0.05% to 75%, preferably in the range of 0.7% to 12%, and more preferably in the range of 1.5% to 6%. The thickness of the mixture layer containing 10 nm (5 n
m which can be changed in the range of m to 45 nm). Here, the molar mass of the molecule of TPD is 5
It is 16.7 g / mol, and the molar mass of the molecule in FIG. 4 (a) is 420.6 g / mol.

The organic electron injection / transport layer 5 has a thickness of 30 nm.
FIG. 6 (can be changed in the range of 10 nm to 80 nm)
Aluminum tris (quino) shown in (k)
line-8-late) (commonly known as Alq3). The molar mass of the molecule of Alq3 is 459.4 g / mol.
It is. Next, the light emitting characteristics of the organic light emitting device manufactured as described above were evaluated. The width of the plurality of transparent electrodes 2 as band-shaped first electrodes and the number of back electrodes 6 as second electrodes formed so as to intersect the transparent electrodes 2 is 1 mm, and the area of the light emitting portion per pixel is 1 mm. The evaluation was performed on an experimental organic light emitting device in which was set to 1 mm ^2, and green light emission with a luminance of 1 cd / m ² was obtained at an applied voltage of 3 V.

The luminance increases as the applied voltage increases.
And a luminance of 90 cd / m when 5 V is applied. ^TwoBecomes 10V mark
Brightness 5500 cd / m when added^TwoAnd when 12 V is applied
Brightness 27000 cd / m^TwoReached. Immediately after production
Brightness 100 cd / m^TwoThe luminous efficiency at the time is 3.7 lm /
W and 5.9 cd / A. JP-A-5-33145
No. 8 discloses the C₆₀And C₇₀Mixture of (C₆₀But
80%) with a molar concentration of 0.80%
Initial luminance of 100 cd / m^TwoLuminous efficiency value at the time
It was much better than 1.48 lm / W.

Further, the initial luminance is 500 cd / m.^TwoFrom, straight
Using a constant current power supply, about 9 mA / cm^TwoConstant power
DC voltage is continuously applied to achieve the current density.
When a luminescence test is performed, the luminance is reduced by half to 250 cd / m^TwoTo
The luminance half-life, which is the time to reach, is 1500 hours
And disclosed in Example 11 of JP-A-8-231951.
The first EL device using decacyclene shown
Initial luminance 500 cd / m ^TwoDC constant current drive from
Far superior to the luminance half-life time of about 900 hours
I was <Fifth Embodiment> 1,7,13-Trimethyltribe
Nzo [c, i, o] triphenylene (see Fig. 4 (a))
Of organic light-emitting device using dope with metal complex
You.

The light emitting layer 4 in the fourth embodiment is TP
D alone, and the organic electron injecting and transporting layer 5 can be changed to a compound of FIG. 4 (a) containing Alq3 as a main component at a weight ratio of 3% (0.05% to 75%, Preferably, it can be changed in the range of 0.7% to 12%, and more preferably, it can be changed in the range of 1.5% to 6%.) A modified fifth embodiment is shown.

The thickness of each layer is the same as in the fourth embodiment. Then, in the same manner as in the fourth embodiment, when an experimental organic light emitting device in which the area of the light emitting portion per pixel was 1 mm ² was evaluated, when the applied voltage was 3 V, the organic electron injecting and transporting layer was evaluated. From 5, brightness 0.8 cd / m
² green luminescence was obtained. Brightness as the applied voltage is increased also increases, luminance 70 cd / m ² becomes at 5V is applied, the brightness 2100cd / m ² becomes at 10V is applied, 1
The luminance reached 15000 cd / m ² when 2 V was applied.

Brightness 100 cd / m immediately after manufacturing^TwoTime
Have luminous efficiencies of 3.0 lm / W and 5.4 cd / A.
Yes, slightly inferior to the fourth embodiment,
C ₆₀And C₇₀Compared with light-emitting devices doped with a mixture of
It was much better.

From the initial luminance of 500 cd / m ² , a continuous light emission test is performed by continuously applying a DC voltage to a constant current density of about 10 mA / cm ² using a DC constant current power supply. And the luminance is reduced by half to 250 cd / m ²
The luminance half-life, which is the time required to reach, was 1000 hours, which was slightly inferior to that of the fourth embodiment, but was superior to that of the light-emitting element using decacyclene. Sixth Embodiment 1,7,13-Triphenyltribenzo [c, i, o] triphenylene (a compound in which the substituents R1 to R3 in the chemical formula of FIG. 5E are phenyl groups) is aromatic. An organic light-emitting device used by doping an amine derivative is manufactured.

A sixth embodiment in which only the compound of FIG. 4A in the fourth embodiment is changed to 1,7,13-triphenyltribenzo [c, i, o] triphenylene is shown.

An evaluation was made on an experimental organic light emitting device in which the area of the light emitting portion per pixel was 1 mm ^{2 in the same} manner as in the fourth embodiment. When the applied voltage was 3 V, the luminance was 0.8 cd / cm 2. m ² orange emission was obtained. As the applied voltage is increased, the luminance also increases, and becomes 80 cd / m ² when 5 V is applied, and becomes 4900 when 10 V is applied.
cd / m ² , and a luminance of 24,000 cd when 12 V is applied.
/ M ² .

The luminous efficiency at a luminance of 100 cd / m ² immediately after production was 3.3 lm / W and 5.4 cd / A, which were slightly inferior to those of the fourth embodiment.
It was excellent in far a mixture of ₆₀ and C ₇₀ as compared to the light-emitting device doped. Also, from an initial luminance of 500 cd / m ² ,
Using a DC constant current power supply, a DC voltage is continuously applied so as to have a constant current density of about 10 mA / cm ² ,
When a continuous light emission test is performed, the luminance is reduced by half to 250 cd / m
^The luminance half-life, which is the time to reach ² , was 1200 hours, which was slightly inferior to that of the fourth embodiment, but superior to the light-emitting element using decacyclene. <Seventh Embodiment> 1,7,13-Tris (1,1 ′
-Biphenyl-4-yl) tribenzo [c, i, o] triphenylene (substituent R1 in the chemical formula of FIG. 5 (e))
Or a compound in which R3 is 1,1′-biphenyl-4-yl) doped with an aromatic amine derivative to produce an organic light emitting device.

Only the material of FIG. 4A in the fourth embodiment is changed to 1,7,13-tris (1,1′-biphenyl-4-yl) tribenzo [c, i, o] triphenylene. A seventh embodiment will be described.

An evaluation was performed on an experimental organic light emitting device in which the area of a light emitting portion per pixel was 1 mm ^{2 in the same} manner as in the fourth embodiment. When the applied voltage was 3 V, the luminance was 0.6 cd / cm 2. m ² red emission was obtained.

The luminance increases as the applied voltage increases.
And a luminance of 65 cd / m when 5 V is applied. ^TwoBecomes 10V mark
Brightness 3900 cd / m when added^TwoAnd when 12 V is applied
Brightness 19000 cd / m^TwoReached.

The luminous efficiency at a luminance of 100 cd / m ² immediately after the production was 2.6 lm / W and 4.9 cd / A, which were slightly inferior to those of the fourth embodiment.
It was excellent in far a mixture of ₆₀ and C ₇₀ as compared to the light-emitting device doped.

Further, a continuous light emission test is performed by continuously applying a DC voltage from an initial luminance of 500 cd / m ² to a constant current density of about 11 mA / cm ² using a DC constant current power supply. And the luminance is reduced by half to 250 cd / m ²
The luminance half-life, which is the time required to reach, was 1000 hours, which was slightly inferior to that of the fourth embodiment, but was superior to that of the light-emitting element using decacyclene. <Comparative Example 1> Next, FIG.
Comparative Example 1 is shown in which the light emitting layer 4 is changed to be composed only of TPD without using the material of (a). In the same manner as in the fourth embodiment, when an experimental organic light emitting device in which the area of the light emitting portion per pixel was 1 mm ² was evaluated, when the applied voltage was 4 V, the organic electron injecting and transporting layer 5 Green light with a luminance of 0.8 cd / m ² was obtained. As the applied voltage is increased, the luminance also increases, and becomes 60 cd / m ² when 5 V is applied, and becomes 900 when 10 V is applied.
cd / m ² , and a luminance of 3200 cd /
m ² .

The luminous efficiency at a luminance of 100 cd / m ² immediately after the production was 2.4 lm / W and 4.8 cd / A, which were considerably inferior to those of the fourth embodiment.

Further, a continuous light emission test is performed by applying a DC voltage continuously from an initial luminance of 500 cd / m ² to a constant current density of about 12 mA / cm ² using a DC constant current power supply. And the luminance is reduced by half to 250 cd / m ²
The luminance half-life, which is the time required to reach, is 19 hours, which is far inferior to the fourth embodiment. <Comparative Example 2> Next, FIG.
Only the material of (a) was used as shown in FIG.
12-Tetraphenylnaphthacene
(Comparative Example 2) changed to (Rubrene).

The molecular mass of the molecule of Rubrene is 53
2.7 g / mol. In the same manner as in the fourth embodiment, evaluation was performed on an experimental organic light-emitting element in which the area of a light-emitting portion per pixel was 1 mm ^{2. When} the applied voltage was 3 V, the luminance was 0.6 cd / m ² . Yellow luminescence was obtained. As the applied voltage increases, the luminance also increases,
The luminance becomes 80 cd / m ² when V is applied, becomes 5000 cd / m ² when 10 V is applied, and becomes 5 when 15 V is applied.
It reached 2000 cd / m ² .

The luminous efficiency at a luminance of 100 cd / m ² immediately after the production was 6.2 lm / W and 8.4 cd / A, which was superior to the fourth embodiment.

From the initial luminance of 500 cd / m ² , a continuous light emission test is performed by continuously applying a DC voltage to a constant current density of about 6 mA / cm ² using a DC constant current power supply. The luminance half-life, which is the time required for the luminance to decrease by half to reach 250 cd / m ² , was 1200 hours, which was inferior to that of the fourth embodiment.

<Other Embodiments> In the above-described embodiment, the material constituting the organic electron injecting and transporting layer 5 is Al.
q3 was used instead of, for example, bis (10-hydroxybenzo [h] quinolinato) beryllium (FIG. 7).
(L)) can be used. Further, the following materials can be used, but are not limited thereto. For example, magnesium bisoxin [a. k. a. Bis (8-quinolinol) magnesium], bis [benzo {f} -8-quinolinol] zinc, bis (2-methyl-
8-quinolinolate) aluminum, indium trisoxine [a. k. a. Tris (8-quinolinol) indium], aluminum tris (5-methyloxin) [a. k. a. Tris (5-methyl-8-quinolinol) aluminum], lithium oxine [a. k.
a. 8-quinolinol lithium], gallium tris (5-chlorooxin) [a. k. a. Tris (5-chloro-8-quinolinol) gallium], calcium bis (5-chlorooxin) [a. k. a. Tris (5-chloro-8-quinolinol) calcium], poly [zinc (I
I) -Bis (8-hydroxy-5-quinolinyl) methene], dilithium epindolidion
e) 1,4-diphenylbutadiene, 1,1,4,4-
Tetraphenylbutadiene, 4,4'-bis [5,7-
Di (t-pentyl-2-benzoxazolyl] stilbene, 2,5-bis [5,7-di (t-pentyl-2-
Benzoxazolyl] thiophene, 2,2 ′-(1,4-
Phenylenedivinylene) bisbenzothiazole, 4,4 '
-(2,2'-bisthiazolyl) biphenyl, 2,5
-Bis [5- (α, α-dimethylbenzyl) -2-benzoxazolyl] thiophene, 2,5-bis [5,7-di (t-pentyl) -2-benzoxazolyl] 3,4-
Diphenylthiophene, trans-stilbene.

In the above-described embodiment, TPD which is a derivative of aromatic amine is used as a material constituting the light emitting layer 4, but the following materials may be used instead. But,
It is not limited to these. For example, 1,1'-
Bis (4-di-p-tolylaminophenyl) cyclohexane, 4,4′-bis (diphenylamino) quadrophenyl, phthalocyanine compound, naphthalocyanine compound, porphyrin compound, oxadiazole, triazole, imidazole, imidazolone, Imidazolethione, pyrazoline, pyrazolone, tetrahydroimidazole, oxazole, oxadiazole, hydrazone, acylhydrazone, polyarylalkane, stilbene, butadiene, benzidine triphenylamine,
Examples thereof include styrylamine-type triphenylamine, diamine-type triphenylamine, and derivatives thereof, and polymer materials such as polyvinylcarbazole, polysilane, and a conductive polymer.

In the above embodiment, only the organic electroluminescent layer 7 having a so-called three-layer structure is described. However, the organic electroluminescent layer 7 may have a two-layer structure including the organic hole injection / transport layer 3 and the light emitting layer 4. It may have a two-layer structure composed of the light emitting layer 4 and the organic electron injection / transport layer 5, or may have a multilayer structure of four or more layers.

In the above-described embodiment, the light emitting device is manufactured by using the transparent electrode 2 formed on the glass substrate 1. Instead, the light emitting device is manufactured by using the substrate on which the thin film transistor is formed. You may do so. As the structure and the forming method of the thin film transistor, known materials such as those disclosed in JP-A-8-54836 and JP-A-8-234683 can be used. It is preferable to use a bottom gate type thin film transistor to be used.

[0081]

According to the organic light-emitting device using the material for an organic light-emitting device of the present invention, aggregation of molecules hardly occurs, and the energy level of electrons in the material is easily brought into an appropriate state. When used in the charge transport layer or the light emitting layer of the device, the light emitting efficiency is improved and the life of the device during continuous light emission is improved.

Further, according to the method for producing a material for an organic light emitting device of the present invention, there is an effect that the material can be produced with a high yield. Specifically, (1) The material for an organic light-emitting device according to claim 1 of the present invention comprises at least one compound having a cyclic partial structure, and the compound having the cyclic partial structure is three-fold rotationally symmetric. Agglomeration of molecules that are problematic in rubrene and decacyclene, which have two-fold rotational symmetry, and quinacridone compounds, whose skeleton structure has two-fold rotational symmetry, because they have a structure that does not have two-fold rotational symmetry Is unlikely to occur.
Further, since the compound has three-fold rotational symmetry, the energy level of electrons of the compound having the cyclic partial structure tends to be in an appropriate state. Can be improved. In addition, when used in the light-emitting layer of an organic light-emitting element, it has three-fold rotational symmetry, so that the peak position of the light-emitting spectrum does not become too long, and the peak width of the light-emitting spectrum does not become too wide. It is easy to obtain a luminescent color, and the quantum yield of luminescence is further improved. (2) The material for an organic light-emitting device according to claim 2 of the present invention, wherein the compound having a cyclic partial structure comprises a skeleton structure having aromaticity at least in part thereof and a substituent bonded to the skeleton structure; 2. The cyclic partial structure according to claim 1, wherein the skeleton structure has a structure having three-fold rotational symmetry and no structure having two-fold rotational symmetry. Has a property similar to the property of the compound having, and the aggregation of molecules is less likely to occur.

Further, the state of the electron energy level of the compound having the cyclic partial structure is determined by the skeleton structure having aromaticity at least in part, and is determined by the substituent bonded to the skeleton structure. Since it is modified, the energy level of the electrons of the compound having the cyclic partial structure is in an appropriate state in its essence, and the state of the energy level can be adjusted by further modifying with a substituent. When used for a light emitting element, the performance of the organic light emitting element can be further improved. In addition, by performing the modification with the substituent, the peak width and the peak wavelength of the emission spectrum can be adjusted, and when used for the light-emitting layer of the organic light-emitting element, a suitable emission color can be more easily obtained. (3) In the material for an organic light-emitting device according to claim 3 of the present invention, the compound having the cyclic partial structure has a planar skeleton structure in the partial structure. The molecule of the compound having the partial structure and another molecule or the molecule of the compound having the cyclic partial structure are easily subjected to a suitable intermolecular interaction, and / or the compound having the cyclic partial structure, and / or Alternatively, the energy level of the electrons of the other molecule is likely to be in an appropriate state, and when used for an organic light-emitting element, the performance of the organic light-emitting element can be further improved. Examples of the preferred intermolecular interaction include a shift of the peak position of the emission spectrum to a longer wavelength side due to an increase in the Stokes shift, and an excimer which is a dimer of the same kind of molecules in an excited state.
The shift of the peak position of the emission spectrum to the longer wavelength side due to the generation of er and the shift of the peak position of the emission spectrum to the longer wavelength side due to the generation of an exciplex, which is a complex of different molecules in the excited state. it can. Therefore, the material for the organic light emitting device of claim 3 is
It is suitable not only as a material for a blue or yellow organic light emitting device, but also particularly as a material for a red organic light emitting device. (4) In the material for an organic light-emitting device according to claim 4 of the present invention, the compound having a cyclic partial structure has a triphenylene carbon skeleton having a stable structure having three-fold rotational symmetry in the partial structure. The energy level of the compound tends to be in an appropriate state, the compound having the cyclic partial structure is hardly subjected to a physical change or a chemical change, and the reliability of an organic light emitting device using the compound is improved. In the case of triphenylene having no substituent, the peak of the emission spectrum has a wavelength of 3
Since there are a plurality of light emission wavelengths in the range of 50 nm to 400 nm, the state of the energy level is adjusted by binding a substituent to the triphenylene carbon skeleton, and in particular, by increasing the peak of the emission spectrum to a longer wavelength, any light emission from blue to red can be obtained. It can be used as a material for an organic light emitting device to be performed. Further, since a compound having a triphenylene carbon skeleton easily generates a triplet excited state, light emission due to a long-lived emission process such as phosphorescence or delayed fluorescence is based on a mechanism of radiation inactivation via the triplet excited state. The phenomenon occurs, and the organic light-emitting device is compared with an organic light-emitting device using a short-lived fluorescence phenomenon based on a mechanism of radiation deactivation via only a singlet excited state, which is generally used conventionally. When a dynamic driving method for intermittently emitting light is applied, flickering of light emission can be suppressed. (5) The material for an organic light-emitting device according to claim 5 of the present invention, wherein the compound having a cyclic partial structure has a three-fold rotational symmetry and does not have a two-fold rotational symmetry. Since the [c, i, o] triphenylene carbon skeleton is included in the partial structure, the energy level of electrons is likely to be in an appropriate state, and the compound having the cyclic partial structure and the material containing the compound are likely to undergo physical changes or It is less susceptible to chemical changes, and the organic light-emitting device using the same improves reliability. Tribenzo [c, i, o] having no substituent
In triphenylene, since the emission spectrum peak exists near the wavelength of about 520 nm, tribenzo [c,
i, o] for organic light-emitting devices that adjust the state of energy level by bonding a substituent to the carbon skeleton of triphenylene, and that emit light of any color from green to red by increasing the peak of the emission spectrum. It can be used as a material. (6) The material for an organic light-emitting device according to claim 6 of the present invention is characterized in that the compound having a cyclic partial structure has a three-fold rotational symmetry and does not have a two-fold rotational symmetry. [C, i, o] a triphenylene carbon skeleton in its partial structure, wherein the 1-position of the triphenylene carbon skeleton and 7
Since a substituent other than a hydrogen atom is bonded to the -position and the 13-position, when the three substituents are the same, the entire molecule has three-fold rotational symmetry and two-fold rotational symmetry. And the energy level of the electrons is more likely to be in an appropriate state, and the compound having the cyclic partial structure and the material containing the compound are more difficult to undergo a physical change or a chemical change. The reliability is further improved in the organic light-emitting device using. Further, when the compound having the cyclic partial structure is synthesized by the method for producing a material for an organic light-emitting device according to claim 12 of the present invention, the substituent is bonded to the ortho position of the styryl group. When the derivative of 5-tristyrylbenzene undergoes a photocyclization reaction, the generation of isomers having different bonding positions of the substituents can be suppressed by the bonding of the substituents to the ortho position, and the yield of synthesis can be reduced. Can be improved. (7) In the material for an organic light-emitting device according to claim 7 of the present invention, since the compound having a cyclic partial structure is 1,7,13-trimethyltribenzo [c, i, o] triphenylene, The emitted light becomes green, and can be used as a material for an organic light-emitting device that emits green light. (8) The material for an organic light emitting device according to claim 8 of the present invention, wherein the compound having the cyclic partial structure is 1,7,13-triphenyltribenzo [c, i, o] triphenylene or a derivative thereof. Accordingly, light emission from the compound becomes orange to red, and the compound can be used as a material for an organic light-emitting element which emits orange to red light. (9) The material for an organic light-emitting device according to claim 9 of the present invention, wherein the compound having the cyclic partial structure is 1,7,13-tris (1,1′-biphenyl-4-yl) tribenzo [c, Since i, o] triphenylene or a derivative thereof is used, the compound emits red light, and can be used as a material for an organic light-emitting element that emits red light. (10) In the material for an organic light-emitting device according to claim 10 of the present invention, the compound having a cyclic partial structure is 1,3,5-tris (ortho-methylstyryl) benzene or a derivative thereof. Light emission from the compound becomes blue to green, and the compound can be used as a material for an organic light-emitting element which emits blue to green light. In addition, the material of FIG. 4B or a derivative thereof may be a mixture of a Z-isomer and an E-isomer in geometrical isomerism, which is a configuration around a double bond. good. (11) A method for producing a material for an organic light-emitting device according to claim 11 of the present invention, comprising the steps of:
Or a derivative thereof (see FIG. 5 (g) or FIG. 4 (d))
And 1,3,5-triformylbenzene (see FIG. 5 (c)) to form a 1,3,5-
Tris styryl benzene or its derivative (Fig. 5 (f)
5), so that the compound of FIG. 5 (f) can be produced with high yield. (12) The method for producing a material for an organic light-emitting device according to claim 12 of the present invention provides a method for producing tribenzo [by the photocyclization reaction of 1,3,5-tristyrylbenzene or a derivative thereof (see FIG. [c, i, o] triphenylene or a derivative thereof (see FIG. 5 (e)) is included, so that the material of FIG. 5 (e) can be produced with high yield. (13) An organic light-emitting device according to claim 13 of the present invention, wherein the material for an organic light-emitting device according to any one of claims 1 to 10 is provided in a light-emitting layer;
Since an aromatic amine derivative is contained, generation of an excited state which is a source of light emission can be caused by the following three types of excitation processes.

In the first type of excitation process, the excited state of the aromatic amine derivative is first generated by the recombination of electrons and holes in the aromatic amine derivative, and subsequently, the excited state of the aromatic amine derivative is excited. The excited state of the material for the organic light emitting device is generated by the energy transfer from the state to the material for the organic light emitting device. The condition for the first type of excitation process to occur is that the energy gap, which is the energy difference between the excited state and the ground state, of the aromatic amine derivative is larger than the energy gap of the material for the organic light emitting device. It is.

The second type of excitation process is as shown in FIG.
Holes are injected into the molecule (B) of the derivative of the aromatic amine to produce a cation radical-like molecular state (B +.), And electrons are injected into the molecule (A) of the material for the organic light emitting device. It is an anion radical-like molecular state (A
−. ) Occurs, and the electron transfer from (A−.) To (B +.) Causes the excited state of the molecule (A) or the excited state of the molecule (B), or a complex of two molecules of A and B in the excited state. Is generated by the exciplex. FIG. 3 shows the concept of the change in electron configuration on the molecular orbital at this time. Regarding the second type of excitation process, for example, B. Sc
Huster et al., J. Am. Chem. So.
c. , 100 (14), 4496-4503 (197
8)).

In the third type of excitation process, electrons and holes are injected into the material for the organic light-emitting device, and recombination of electrons and holes in the material for the organic light-emitting device causes The excited state of the material is directly generated. The condition for the third type of excitation process to occur is that electrons are injected into the material for the organic light-emitting device, so that the lowest unoccupied orbital of the material for the organic light-emitting device, that is, the energy level of LUMO, Not more than 0.5 electron volts (eV) higher than the LUMO energy level of the electron transport layer provided on the cathode side in contact with the electrode (or the cathode if no electron transport layer is provided) (more preferably Is not higher than 0.2 eV) is the first necessary condition, and
Since holes are injected into the material for the organic light-emitting element, the highest occupied orbital of the material for the organic light-emitting element, that is, the energy level of HOMO, is determined by the hole transport provided on the anode side in contact with the light-emitting layer. Second, the energy level of the HOMO of the layer (of the anode if the hole transport layer is not provided) should not be lower than 0.5 eV (more preferably not lower than 0.2 eV). This is a necessary condition. Third
See, for example, Fujii et al.
romol. Symp. 125, 77-82 (199
7)).

If the above two conditions are satisfied, the third type of excitation process may occur in parallel with the third type of excitation process or in addition to the first and / or second type of excitation process. This allows the excited state to be generated efficiently,
An organic light-emitting device having excellent luminous efficiency and having a long lifetime during continuous light emission can be obtained. (14) The organic light-emitting device according to claim 14 of the present invention, wherein the light-emitting layer includes the material for an organic light-emitting device according to any one of claims 1 to 10;
Since the metal complex and the metal complex are contained, the generation of the excited state which is the source of light emission can be caused by three kinds of excitation processes as in the case of claim 13, and the two conditions are satisfied. In this case, the excited state is efficiently generated by the third type of excitation process or by the third type of excitation process occurring in addition to the first and / or second type of excitation process. As a result, an organic light-emitting device having excellent luminous efficiency and a long lifetime of the device during continuous light emission can be obtained. However, in the first type of excitation process in this case, the excited state of the metal complex is first generated by recombination of electrons and holes in the metal complex, and subsequently, the excited state of the metal complex is converted from the excited state of the metal complex to the organic light emitting device. The excited state of the material for the organic light emitting device is generated by the energy transfer to the material. In the second type of excitation process in this case, electrons are injected into the metal complex (C) to generate an anion radical-like molecular state (C−.), And the molecule (M−) of the material for the organic light emitting device ( Holes are injected into (A) to produce (A +.), Which is a cation radical-like molecular state, and (C)
−. ) From (A +.) To the excited state of molecule (A), or the excited state of complex (C), or exc, which is a complex of two molecules of A and C in the excited state.
generated by the iplex.

[Brief description of the drawings]

FIG. 1 is a sectional view of an organic light emitting device according to a fourth embodiment of the present invention.

FIG. 2 is an explanatory diagram of a second type of excitation process according to claim 13 of the present invention.

FIG. 3 is a conceptual diagram showing a change in electron configuration on a molecular orbit according to a thirteenth aspect of the present invention.

FIG. 4 is a view showing a chemical formula according to the present invention.

FIG. 5 is a view showing a chemical formula according to the present invention.

FIG. 6 is a view showing a chemical formula according to the present invention.

FIG. 7 is a view showing a chemical formula according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Glass substrate 2 ... Transparent electrode 3 ... Organic hole injection / transport layer 4 ... Light emitting layer 5 ... Organic electron injection / transport layer 6 ... Back electrode 7 ... Organic electroluminescent layer 8 ... Protective film

Claims (14)

[Claims] 1. A compound comprising at least one compound having a cyclic partial structure, the compound having a structure having three-fold rotational symmetry as a whole and having no structure having two-fold rotational symmetry. Characteristic materials for organic light emitting devices. 2. A compound comprising at least one compound having a cyclic partial structure, the compound comprising at least a part of a skeleton structure having aromaticity and a substituent bonded to the skeleton structure. A material for an organic light-emitting device, wherein the skeletal structure has a structure having three-fold rotational symmetry and not having two-fold rotational symmetry. 3. The material for an organic light emitting device according to claim 1, wherein the compound has a planar skeleton structure in a partial structure thereof. 4. The material for an organic light emitting device according to claim 1, wherein said compound has a triphenylene carbon skeleton in its partial structure. 5. The compound according to claim 1, wherein the compound is tribenzo [c, i,
o] The material for an organic light emitting device according to any one of claims 1 to 4, wherein the material has a triphenylene carbon skeleton in its partial structure. 6. The compound according to claim 1, wherein the compound is tribenzo [c, i,
o] having a triphenylene carbon skeleton in its partial structure, wherein the 1-position, 7-position, and 13-position of the triphenylene carbon skeleton are
6. The material for an organic light emitting device according to claim 5, wherein a substituent other than a hydrogen atom is bonded to the position. 7. The material for an organic light-emitting device according to claim 6, wherein the compound is 1,7,13-trimethyltribenzo [c, i, o] triphenylene. 8. The material for an organic light emitting device according to claim 6, wherein said compound is 1,7,13-triphenyltribenzo [c, i, o] triphenylene or a derivative thereof. 9. The compound according to claim 1, wherein the compound is 1,7,13-tris (1,1′-biphenyl-4-yl) tribenzo [c,
7. The material for an organic light-emitting device according to claim 6, wherein the material is [i, o] triphenylene or a derivative thereof. 10. The material for an organic light emitting device according to claim 2, wherein the compound is 1,3,5-tris (ortho-methylstyryl) benzene or a derivative thereof. 11. The compound is obtained by a carbon-carbon bond forming reaction between benzyltriphenylphosphonium bromide or a derivative thereof and 1,3,5-triformylbenzene, and 1,3,5-tristyrylbenzene, Or a step of producing a derivative thereof.
11. The method for producing a material for an organic light-emitting device according to any one of items 10 to 10. 12. The method according to claim 1, wherein the compound includes a step of generating tribenzo [c, i, o] triphenylene or a derivative thereof by a photocyclization reaction of 1,3,5-tristyrylbenzene or a derivative thereof. The method for producing a material for an organic light-emitting device according to claim 5. 13. An organic light emitting device, wherein the light emitting layer contains the material for an organic light emitting device according to claim 1 and a derivative of an aromatic amine. 14. An organic light-emitting device, wherein the light-emitting layer contains the material for an organic light-emitting device according to claim 1 and a metal complex.