WO2013161468A1 - Organic electroluminescent element - Google Patents

Abstract

The present invention addresses the problem of providing an organic electroluminescent element which has high luminous efficiency and improved service life in cases where the element is caused to emit light with high luminance. An organic electroluminescent element of the present invention comprises an organic layer that is held between the positive electrode and the negative electrode and includes a light emitting layer. The organic electroluminescent element is characterized in that: the light emitting layer contains a host compound and a phosphorescent dopant represented by general formula (1); and the content of the phosphorescent dopant in the light emitting layer is within the range of 8-35% by volume relative to the content of the host compound.

Description

Organic electroluminescence device

The present invention relates to an organic electroluminescence element.

An organic electroluminescence element (hereinafter also referred to as an organic EL element) has a configuration in which a light emitting layer containing a light emitting compound is sandwiched between a cathode and an anode, and is injected from the anode by applying an electric field. A light emitting device using excitons (excitons) by recombining electrons injected from holes and cathodes in the light emitting layer, and using light emission (fluorescence or phosphorescence) when the excitons are deactivated It is. An organic EL element is an all-solid-state element composed of an organic material film having a thickness of only a submicron between electrodes, and can emit light at a voltage in the range of several volts to several tens of volts. Therefore, it is expected to be used for next-generation flat display and lighting.

As for development of organic EL elements for practical use, Princeton University has reported organic EL elements that use phosphorescence emission from excited triplets (see, for example, Non-Patent Document 1), and since then phosphorescence at room temperature. Research on materials exhibiting the above has become active (see, for example, Non-Patent Document 2).

Furthermore, organic EL elements that utilize phosphorescence emission can in principle achieve a light emission efficiency that is approximately four times that of organic EL elements that utilize previous fluorescence emission. Research and development of device layer configurations and electrodes are performed all over the world. For example, many compounds have been studied focusing on heavy metal complexes such as iridium complexes (see Non-Patent Document 3, for example).

As described above, the phosphorescence emission method is a method having a very high potential. However, an organic EL element using phosphorescence emission is greatly different from an organic EL element using fluorescence emission, and the position of the emission center is controlled. The method, particularly how to recombine within the light emitting layer and how to stably emit light, is an important technical issue in improving the efficiency and lifetime of the device.

Therefore, in recent years, a multi-layered element having a hole transport layer located on the anode side of the light emitting layer and an electron transport layer located on the cathode side of the light emitting layer in a form adjacent to the light emitting layer is well known. . In addition, a mixed layer using a host compound and a phosphorescent compound as a dopant is often used for the light emitting layer.

On the other hand, from the viewpoint of materials, high carrier transportability and thermally and electrically stable materials are demanded. In particular, when utilizing blue phosphorescence, since the blue phosphorescent compound itself has high triplet excited state energy (T1), the development of applicable peripheral materials and the precise emission center There is a strong demand for control.

As a method for reducing power consumption and improving luminous efficiency, improving carrier transport in the light emitting layer can be mentioned. Since the host compound, which is an electron transport medium, exists in the light emitting layer at a high concentration, electrons can easily move. However, the light emitting dopant, which is a hole transport medium, has a low concentration, and carriers are likely to stagnate, causing a voltage increase. It has become. Although the hole transportability can be improved by increasing the concentration of the luminescent dopant, it is very difficult to obtain high luminescent properties at low power by quenching the concentration due to aggregation / association of the luminescent dopant itself. There is a problem that the lifetime is shortened by increasing the concentration of.

Recently, Patent Documents 1 and 2 disclose that the emission lifetime of an organic EL element is improved by using a metal complex having a specific ligand as a blue phosphorescent dopant having a high potential.

However, in the techniques described in Patent Documents 1 and 2, the light emission lifetime of the organic EL element when emitting light with low luminance is improved, but the life of the organic EL element when emitting light with high luminance is improved. Short was the problem.

US Patent Application Publication No. 2011/0057559 US Patent Application Publication No. 2011/0204333

The present invention has been made in view of the above problems and situations, and a solution to the problem is to provide an organic electroluminescence device having high luminous efficiency and improved lifetime when emitting light with high luminance. It is.

In order to improve the hole transportability in the process of studying the cause of the above problems, etc., in order to solve the above problems, the present inventor relates to the present invention even if a phosphorescent dopant is contained in the light emitting layer at a high concentration. In the case of using a phosphorescent dopant, concentration quenching was suppressed, and it was found that the lifetime was long when lit with high luminance, and the present invention was achieved.

That is, the said subject which concerns on this invention is solved by the following means.
1. In an organic electroluminescence device in which an organic layer including a light emitting layer is sandwiched between an anode and a cathode, the light emitting layer contains a host compound and a phosphorescent dopant represented by the following general formula (1), and the light emission An organic electroluminescence device, wherein the content of the phosphorescent dopant in the layer is in the range of 8 to 35% by volume with respect to the content of the host compound.

[In General Formula (1), Ring Am, Ring An, Ring Bm and Ring Bn represent a 5-membered or 6-membered aromatic hydrocarbon ring or aromatic heterocycle. Ar represents an aromatic hydrocarbon ring, an aromatic heterocycle, a non-aromatic hydrocarbon ring or a non-aromatic heterocycle. R1m, R2m, R1n and R2n each independently represents an alkyl group having 2 or more carbon atoms, an aromatic hydrocarbon ring group, an aromatic heterocyclic group, a non-aromatic hydrocarbon ring group or a non-aromatic heterocyclic group, Furthermore, you may have a substituent. Each Ra is independently a hydrogen atom, halogen atom, cyano group, alkyl group, alkenyl group, alkynyl group, alkoxy group, amino group, silyl group, arylalkyl group, aryl group, heteroaryl group, non-aromatic hydrocarbon ring Represents a linking group that forms a ring with a group, a non-aromatic heterocyclic group or Ar. Rb and Rc are each independently a hydrogen atom, halogen atom, cyano group, alkyl group, alkenyl group, alkynyl group, alkoxy group, amino group, silyl group, arylalkyl group, aryl group, heteroaryl group, non-aromatic carbonization Represents a hydrogen ring group or a non-aromatic heterocyclic group. Ra, Rb and Rc may further have a substituent. na and nc represent 1 or 2, and nb represents an integer of 1 to 4. m represents 1 or 2. n represents 1 or 2. m + n is 3. Note that the structures of the three ligands coordinated to Ir are not all the same. ]
2. 2. The organic electroluminescence device according to claim 1, wherein the content of the phosphorescent dopant in the light emitting layer is in the range of 16 to 30% by volume with respect to the content of the host compound.
3. The phosphorescent dopant represented by the general formula (1) is a phosphorescent dopant represented by the following general formula (2), wherein the organic electroluminescent element according to the first or second item is characterized.

[In General Formula (2), Ar represents an aromatic hydrocarbon ring, an aromatic heterocyclic ring, a non-aromatic hydrocarbon ring or a non-aromatic heterocyclic ring. R1m, R2m, R1n and R2n each independently represents an alkyl group having 2 or more carbon atoms, an aromatic hydrocarbon ring group, an aromatic heterocyclic group, a non-aromatic hydrocarbon ring group or a non-aromatic heterocyclic group, Furthermore, you may have a substituent. Each Ra is independently a hydrogen atom, halogen atom, cyano group, alkyl group, alkenyl group, alkynyl group, alkoxy group, amino group, silyl group, arylalkyl group, aryl group, heteroaryl group, non-aromatic hydrocarbon ring Represents a linking group that forms a ring with a group, a non-aromatic heterocyclic group or Ar. Rc each independently represents a hydrogen atom, halogen atom, cyano group, alkyl group, alkenyl group, alkynyl group, alkoxy group, amino group, silyl group, arylalkyl group, aryl group, heteroaryl group, non-aromatic hydrocarbon ring Represents a group or a non-aromatic heterocyclic group. Ra and Rc may further have a substituent. na and nc represent 1 or 2. m represents 1 or 2. n represents 1 or 2. m + n is 3. Note that the structures of the three ligands coordinated to Ir are not all the same. ]
4). The phosphorescent dopant represented by the general formula (1) is a phosphorescent dopant represented by the following general formula (3), The organic electroluminescent element according to the first or second item.

[In General Formula (3), R1m, R2m, R1n and R2n are each independently an alkyl group having 2 or more carbon atoms, an aromatic hydrocarbon ring group, an aromatic heterocyclic group, a non-aromatic hydrocarbon ring group or It represents a non-aromatic heterocyclic group and may further have a substituent. Ra, Rc and Ra ₃ are each independently a hydrogen atom, halogen atom, cyano group, alkyl group, alkenyl group, alkynyl group, alkoxy group, amino group, silyl group, arylalkyl group, aryl group, heteroaryl group, non- Represents an aromatic hydrocarbon ring group or a non-aromatic heterocyclic group; Ra, Ra ₃ and Rc may further have a substituent. na and nc represent 1 or 2. nR3 represents an integer of 1 to 5. m represents 1 or 2. n represents 1 or 2. m + n is 3. Note that the structures of the three ligands coordinated to Ir are not all the same. ]
5. The phosphorescent dopant represented by the general formula (1) is a phosphorescent dopant represented by the following general formula (4), The organic electroluminescent element according to the first or second item.

[In General Formula (4), R1m, R2m, R1n and R2n each independently represents an alkyl group having 2 or more carbon atoms, an aromatic hydrocarbon ring group, an aromatic heterocyclic group, a non-aromatic hydrocarbon ring group or a non-aromatic group. Represents an aromatic heterocyclic group and may further have a substituent. Ra, Rc and Ra ₃ are each independently a hydrogen atom, halogen atom, cyano group, alkyl group, alkenyl group, alkynyl group, alkoxy group, amino group, silyl group, arylalkyl group, aryl group, heteroaryl group, non- It represents an aromatic hydrocarbon ring group or a non-aromatic heterocyclic group, and may further have a substituent. na and nc represent 1 or 2. nR3 represents an integer of 1 to 4. X represents O, S, SiRz1Rz2, NRz1 or CRz1Rz2. Rz1 and Rz2 represent an alkyl group, an aromatic hydrocarbon ring group, an aromatic heterocyclic group, a non-aromatic hydrocarbon ring group, or a non-aromatic heterocyclic group. m represents 1 or 2. n represents 1 or 2. m + n is 3. ]
6). The phosphorescent dopant represented by the general formula (1) is a phosphorescent dopant represented by the following general formula (5), wherein the organic electroluminescent element according to the first or second item is characterized.

[In General Formula (5), R1m, R2m, R1n and R2n each independently represents an alkyl group having 2 or more carbon atoms, an aromatic hydrocarbon ring group, an aromatic heterocyclic group, a non-aromatic hydrocarbon ring group or a non-aromatic group. Represents an aromatic heterocyclic group and may further have a substituent. Ra, Rc and Ra ₃ are each independently a hydrogen atom, halogen atom, cyano group, alkyl group, alkenyl group, alkynyl group, alkoxy group, amino group, silyl group, arylalkyl group, aryl group, heteroaryl group, non- It represents an aromatic hydrocarbon ring group or a non-aromatic heterocyclic group, and may further have a substituent. na and nc represent 1 or 2. nR3 represents an integer of 1 to 4. X represents O, S, SiRz1Rz2, NRz1 or CRz1Rz2. Rz1 and Rz2 represent an alkyl group, an aromatic hydrocarbon ring group, an aromatic heterocyclic group, a non-aromatic hydrocarbon ring group, or a non-aromatic heterocyclic group. m represents 1 or 2. n represents 1 or 2. m + n is 3. ]

By the above means of the present invention, it is possible to provide an organic electroluminescence device having high emission efficiency and a long lifetime when emitting light with high luminance.

The expression mechanism or action mechanism of the effect of the present invention is not clear, but is presumed as follows.

When an organic electroluminescence device emits light with high luminance, the lifetime of the device is drastically reduced. One reason is that the device becomes high temperature due to high luminance light emission and the phosphorescent dopant is deteriorated by heat. . Initially, the phosphorescent dopant that was in an amorphous state tends to become fine crystals by heating.

The phosphorescent dopant according to the present invention has a substituent large enough to interfere with the imidazole ring in the ring bonded to the nitrogen atom of the imidazole ring. Therefore, it is considered that crystallization is suppressed and the lifetime is improved even when exposed to a high-temperature environment when emitting light with high brightness.

Also, it is considered that concentration quenching is unlikely to occur because it is difficult to crystallize.

Schematic diagram showing an example of a display device composed of organic EL elements Schematic diagram of display part A Schematic diagram of pixels Schematic diagram of passive matrix type full color display device Schematic of lighting device Schematic diagram of lighting device Relationship between doping rate and life when initially lit at 1000 cd / m ² Relationship between doping rate and life when initially lit at 3000 cd / m ²

In the organic electroluminescence device of the present invention, an organic layer including a light emitting layer is sandwiched between an anode and a cathode, and the light emitting layer contains a host compound and a phosphorescent dopant represented by the general formula (1). The phosphorescent dopant content in the light emitting layer is in the range of 8 to 35% by volume with respect to the host compound content. This feature is a technical feature common to the inventions according to claims 1 to 6.

In an embodiment of the present invention, since the lifetime reduction due to high-luminance emission can be further suppressed, the content of the phosphorescent dopant is in the range of 16 to 30% by volume with respect to the content of the host compound. Is preferred. Moreover, it is preferable from a viewpoint of the effect expression of this invention that the phosphorescence dopant represented by the said General formula (1) is a phosphorescence dopant represented by the said General formula (2).

Furthermore, in the present invention, the phosphorescent dopant represented by the general formula (1) is preferably a phosphorescent dopant represented by the general formula (3), (4) or (5). Thereby, the further effect of this invention is acquired.

The organic electroluminescence element of the present invention can be suitably included in display devices, displays, and various light emission sources.

Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In the present application, “˜” is used to mean that the numerical values described before and after it are included as a lower limit value and an upper limit value.

<< Constituent layers of organic EL elements >>
The constituent layers of the organic EL element of the present invention will be described. In the organic EL device of the present invention, preferred specific examples of the layer structure of various organic layers sandwiched between the anode and the cathode are shown below, but the present invention is not limited thereto.

(I) Anode / light emitting layer unit / electron transport layer / cathode (ii) Anode / hole transport layer / light emitting layer unit / electron transport layer / cathode (iii) Anode / hole transport layer / light emitting layer unit / hole blocking Layer / electron transport layer / cathode (iv) anode / hole transport layer / light emitting layer unit / hole blocking layer / electron transport layer / cathode buffer layer / cathode (v) anode / anode buffer layer / hole transport layer / light emission Layer unit / hole blocking layer / electron transport layer / cathode buffer layer / cathode Further, the light emitting layer unit may have a non-light emitting intermediate layer between a plurality of light emitting layers, and the intermediate layer is charged. A multi-photon unit configuration that is a generation layer may be used. In this case, as the charge generation layer, ITO (indium tin oxide), IZO (indium zinc oxide), ZnO ₂ , TiN, ZrN, HfN, TiO _x , VO _x , CuI, InN, GaN, CuAlO _{2 are used.} , CuGaO ₂ , SrCu ₂ O ₂ , LaB ₆ , RuO _{2 and} other conductive inorganic compound layers, Au / Bi ₂ O _{3 and} other two-layer films, SnO ₂ / Ag / SnO ₂ , ZnO / Ag / ZnO, Bi ₂ O ₃ / Au / Bi ₂ O ₃ , TiO ₂ / TiN / TiO ₂ , TiO ₂ / ZrN / TiO _{2 and} other multilayer films, C60 and other fullerenes, conductive organic layers such as oligothiophene, metal phthalocyanine , Conductive organic compound layers such as metal-free phthalocyanines, metal porphyrins, metal-free porphyrins, and the like.

The light emitting layer in the organic EL element of the present invention is preferably a white light emitting layer, and an illumination device using these is preferable.

Each layer constituting the organic EL element of the present invention will be described below.

<Light emitting layer>
The light emitting layer according to the present invention is a layer that emits light by recombination of electrons and holes injected from the electrode or the electron transport layer and the hole transport layer, and the light emitting portion is in the layer of the light emitting layer. May be the interface between the light emitting layer and the adjacent layer.

The total thickness of the light emitting layer is not particularly limited, but from the viewpoint of improving the uniformity of the film, preventing application of unnecessary high voltage during light emission, and improving the stability of the emission color with respect to the drive current. It is preferably adjusted in the range of 2 nm to 5 μm, more preferably adjusted in the range of 2 to 200 nm, particularly preferably in the range of 5 to 100 nm.

For the production of the light-emitting layer, a light-emitting dopant or a host compound, which will be described later, is used. And the like can be formed by a method, an inkjet method, a printing method, a spray coating method, a curtain coating method, an LB method (Langmuir Brodgett method, etc.).

The light emitting layer of the organic EL device of the present invention contains a phosphorescent dopant (also referred to as a phosphorescent dopant) and a light emitting host compound.

(Phosphorescent dopant)
The phosphorescent dopant according to the present invention will be described.

The phosphorescent dopant according to the present invention is a compound in which light emission from an excited triplet is observed, specifically, a compound that emits phosphorescence at room temperature (25 ° C.), and a phosphorescence quantum yield is 25 ° C. The phosphorescence quantum yield is preferably 0.1 or more.

The phosphorescent quantum yield can be measured by the method described in Spectroscopic II, page 398 (1992 edition, Maruzen) of the Fourth Edition Experimental Chemistry Course 7. Although the phosphorescence quantum yield in a solution can be measured using various solvents, the phosphorescence dopant according to the present invention achieves the phosphorescence quantum yield (0.01 or more) in any solvent. That's fine.

In the light emitting layer, the content of the phosphorescent dopant represented by the general formula (1) according to the present invention is in the range of 8 to 35% by volume with respect to the content of the host compound.

The content of the phosphorescent dopant in the light emitting layer is within the range of 8 to 35% by volume with respect to the content of the host compound. This means that when the light emitting layer is formed by co-evaporation of both, Under these conditions, the ratio of the film thickness increase rate when the phosphorescent dopant is vapor-deposited alone to the film thickness increase rate when the host compound is vapor-deposited alone (also referred to as vapor deposition rate) is 8 to 35% by volume. It means to be within the range.

Also, when the light emitting layer is produced by a wet process, the specific gravity is obtained from the mass and thickness of the layer formed by vapor-depositing the phosphorescent dopant and the host compound individually. The value obtained by dividing the value of the ratio of the phosphorescent dopant mass to the mass of the host compound added to the wet process coating liquid by the ratio of the specific gravity of the phosphorescent dopant to the specific gravity of the host compound is the value of the phosphorescent dopant relative to the host compound. The volume ratio.

There are two types of light emission of the phosphorescent dopant in principle. One is the recombination of carriers on the host compound to which carriers are transported to generate the excited state of the luminescent host compound, and this energy is used as the phosphorescent dopant. It is an energy transfer type in which light emission from a phosphorescent dopant is obtained by moving to. The other is a carrier trap type in which a phosphorescent dopant becomes a carrier trap, and carrier recombination occurs on the phosphorescent dopant, and light emission from the phosphorescent dopant is obtained. In any case, it is a condition that the excited state energy of the phosphorescent dopant is lower than the excited state energy of the host compound.

Here, as a result of intensive studies in order to achieve the object of the present invention, the present inventors have added the phosphorescent dopant represented by the general formula (1) as a host compound to the organic layer of the organic EL element. In contrast, it has been clarified that the light emission efficiency of the organic EL device and the lifetime when emitting light with high luminance can be improved by adding the content in the range of 8 to 35% by volume.

The improvement of the luminous efficiency and the lifetime is achieved by making any one of a plurality of ligands coordinated to an iridium atom different from each other and changing R1m, R2m, R1n and R2n in the general formula (1) to 2 carbon atoms. By using the above substituents, the interaction between iridium complexes is relaxed and aggregation and association are suppressed even at high concentrations, improving concentration quenching and preventing deterioration due to heat generated by high-intensity luminescence. It is surmised that this was achieved. Thereby, the luminous efficiency of the organic EL element was able to be improved. Furthermore, it discovered that the improvement in the light emission lifetime in the high-intensity light emission of an organic EL element was achieved because the said phosphorescence dopant was contained in the organic EL element.

Therefore, the organic EL device of the present invention is configured such that the phosphorescent dopant represented by the general formula (1) is contained in the light emitting layer in the range of 8 to 35% by volume with respect to the host compound. Preferably, it is contained within the range of 16 to 30% by volume.

(1) Phosphorescent dopant represented by general formula (1) The phosphorescent dopant contained as an organic EL element material in the organic EL element of the present invention will be described. The phosphorescent dopant according to the present invention is represented by the following general formula (1).

In general formula (1), ring An, ring Am, ring Bn, and ring Bm represent a 5-membered or 6-membered aromatic hydrocarbon ring or aromatic heterocycle.

In the general formula (1), examples of the 5-membered or 6-membered aromatic hydrocarbon ring represented by the ring An, the ring Am, the ring Bn, and the ring Bm include a benzene ring.

In the general formula (1), examples of the 5-membered or 6-membered aromatic heterocycle represented by ring An, ring Am, ring Bn and ring Bm include a furan ring, a thiophene ring, an oxazole ring, a pyrrole ring, and a pyridine. A ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, a triazine ring, an oxadiazole ring, a triazole ring, an imidazole ring, a pyrazole ring, a thiazole ring, and the like.

Preferably, at least one of rings Bn and Bm is a benzene ring, more preferably at least one of rings An and Am is a benzene ring.

In the general formula (1), Ar represents an aromatic hydrocarbon ring, an aromatic heterocycle, a non-aromatic hydrocarbon ring or a non-aromatic heterocycle.

In the general formula (1), examples of the aromatic hydrocarbon ring represented by Ar include a benzene ring, biphenyl ring, naphthalene ring, azulene ring, anthracene ring, phenanthrene ring, pyrene ring, chrysene ring, naphthacene ring, and triphenylene. Ring, o-terphenyl ring, m-terphenyl ring, p-terphenyl ring, acenaphthene ring, coronene ring, fluorene ring, fluoranthrene ring, naphthacene ring, pentacene ring, perylene ring, pentaphen ring, picene ring, pyrene Ring, pyranthrene ring, anthraanthrene ring and the like.

In the general formula (1), examples of the aromatic heterocycle represented by Ar include a silole ring, a furan ring, a thiophene ring, an oxazole ring, a pyrrole ring, a pyridine ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, and a triazine ring. , Oxadiazole ring, triazole ring, imidazole ring, pyrazole ring, thiazole ring, indole ring, benzimidazole ring, benzthiazole ring, benzoxazole ring, quinoxaline ring, quinazoline ring, phthalazine ring, thienothiophene ring, carbazole ring, aza Carbazole ring (represents any one or more of the carbon atoms constituting the carbazole ring replaced by a nitrogen atom), dibenzosilole ring, dibenzofuran ring, dibenzothiophene ring, benzothiophene ring or dibenzofuran ring Any one Rings substituted with nitrogen atom, benzodifuran ring, benzodithiophene ring, acridine ring, benzoquinoline ring, phenazine ring, phenanthridine ring, phenanthroline ring, cyclazine ring, kindrin ring, tepenidine ring, quinindrine ring, triphenodithia Gin ring, triphenodioxazine ring, phenanthrazine ring, anthrazine ring, perimidine ring, naphthofuran ring, naphthothiophene ring, naphthodifuran ring, naphthodithiophene ring, anthrafuran ring, anthradifuran ring, anthrathiophene ring, anthradithiophene Ring, thianthrene ring, phenoxathiin ring, dibenzocarbazole ring, indolocarbazole ring, dithienobenzene ring and the like.

In the general formula (1), examples of the non-aromatic hydrocarbon ring represented by Ar include cycloalkane (eg, cyclopentane ring, cyclohexane ring, etc.), cycloalkoxy group (eg, cyclopentyloxy group, cyclohexyloxy group). Etc.), a cycloalkylthio group (for example, a cyclopentylthio group, a cyclohexylthio group, etc.), a cyclohexylaminosulfonyl group, a tetrahydronaphthalene ring, a 9,10-dihydroanthracene ring, a biphenylene ring and the like.

In the general formula (1), examples of the non-aromatic heterocycle represented by Ar include an epoxy ring, an aziridine ring, a thiirane ring, an oxetane ring, an azetidine ring, a thietane ring, a tetrahydrofuran ring, a dioxolane ring, a pyrrolidine ring, and a pyrazolidine. Ring, imidazolidine ring, oxazolidine ring, tetrahydrothiophene ring, sulfolane ring, thiazolidine ring, ε-caprolactone ring, ε-caprolactam ring, piperidine ring, hexahydropyridazine ring, hexahydropyrimidine ring, piperazine ring, morpholine ring, tetrahydropyran Ring, 1,3-dioxane ring, 1,4-dioxane ring, trioxane ring, tetrahydrothiopyran ring, thiomorpholine ring, thiomorpholine-1,1-dioxide ring, pyranose ring, diazabicyclo [2,2,2]- Octane ring Examples include enoxazine ring, phenothiazine ring, oxanthrene ring, thioxanthene ring, phenoxathiin ring and the like.

In the general formula (1), these rings represented by Ar may have a substituent, and the substituents may be bonded to each other to form a ring.

In the general formula (1), Ar is preferably an aromatic hydrocarbon ring or an aromatic heterocyclic ring, more preferably an aromatic hydrocarbon ring, and still more preferably a benzene ring.

In general formula (1), R1m and R2m are each independently an alkyl group having 2 or more carbon atoms, an aromatic hydrocarbon ring group, an aromatic heterocyclic group, a non-aromatic hydrocarbon ring group, or a non-aromatic heterocyclic ring. Represents a group, and may further have a substituent.

In the general formula (1), examples of the alkyl group represented by R1m and R2m include an ethyl group, an isopropyl group, an n-butyl group, a t-butyl group, an n-hexyl group, a 2-methylhexyl group, and a pentyl group. Adamantyl group, n-decyl group, n-dodecyl group and the like.

In the general formula (1), the aromatic hydrocarbon ring group, aromatic heterocyclic group, non-aromatic hydrocarbon ring group or non-aromatic heterocyclic group represented by R1m and R2m is the above-described general formula (1 ), A monovalent group derived from an aromatic hydrocarbon ring, an aromatic heterocyclic ring, a non-aromatic hydrocarbon ring or a non-aromatic heterocyclic ring represented by Ar.

In the general formula (1), an alkyl group having 2 or more carbon atoms, an aromatic hydrocarbon ring group, an aromatic heterocyclic group, a non-aromatic hydrocarbon ring group or a non-aromatic heterocyclic group represented by R1m and R2m Further, examples of the substituent that may be included include a halogen atom, a cyano group, an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an amino group, a silyl group, an arylalkyl group, an aryl group, a heteroaryl group, a non-aryl group, An aromatic hydrocarbon ring group or a non-aromatic heterocyclic group is exemplified.

In the general formula (1), it is preferable that R1m and R2m are both an alkyl group or a cycloalkyl group having 2 or more carbon atoms, and one of R1m and R2m is a branched alkyl group having 3 or more carbon atoms. It is also preferable. More preferably, both R1m and R2m are branched alkyl groups having 3 or more carbon atoms.

In the general formula (1), R1n and R2n have the same meanings as R1m and R2m in the general formula (1).

In the general formula (1), each Ra is independently a hydrogen atom, halogen atom, cyano group, alkyl group, alkenyl group, alkynyl group, alkoxy group, amino group, silyl group, arylalkyl group, aryl group, heteroaryl group , A non-aromatic hydrocarbon ring group, a non-aromatic heterocyclic group or a linking group that forms a ring with Ar. Rb and Rc are each independently a hydrogen atom, halogen atom, cyano group, alkyl group, alkenyl group, alkynyl group, alkoxy group, amino group, silyl group, arylalkyl group, aryl group, heteroaryl group, non-aromatic Represents a hydrocarbon ring group or a non-aromatic heterocyclic group. Ra, Rb and Rc may further have a substituent. In addition, a substituent here means what may have in the range which does not inhibit the function of the compound based on this invention. The same applies to the following.

In the general formula (1), the aryl group and heteroaryl group represented by Ra, Rb and Rc are derived from the aromatic hydrocarbon ring and aromatic heterocycle represented by Ar in the above general formula (1). And a monovalent group.

In the general formula (1), as the non-aromatic hydrocarbon ring group and non-aromatic heterocyclic group represented by Ra, Rb and Rc, the non-aromatic carbon represented by Ar in the above-mentioned general formula (1) And monovalent groups derived from a hydrogen ring and a non-aromatic heterocyclic ring.

In the general formula (1), Ra preferably represents a linking group that forms a ring together with an alkyl group, a hydrogen atom, a halogen atom, a cyano group, an aryl group, or Ar, and when Ra represents a linking group, , Ra represents O, S, SiRz1Rz2, NRz1 or CRz1Rz2. Rb and Rc preferably represent an alkyl group, a hydrogen atom, a halogen atom, a cyano group or an aryl group, and particularly preferably represent a methyl group, a hydrogen atom, a fluorine atom, a cyano group or a phenyl group. Rz1 and Rz2 represent an alkyl group, an aromatic hydrocarbon ring group, an aromatic heterocyclic group, a non-aromatic hydrocarbon ring group, or a non-aromatic heterocyclic group.

In the general formula (1), na and nc represent 1 or 2, and nb represents an integer of 1 to 4.

In the general formula (1), m represents 1 or 2, n represents 1 or 2, and m + n is 3. Since a longer lifetime can be achieved as the phosphorescent dopant according to the present invention, it is preferable to use a phosphorescent dopant in which m represents 1 and n represents 2 in the general formula (1).

In the general formula (1), the structures of the three ligands coordinated to Ir are not all the same.

(2) The phosphorescent dopant represented by the general formula (2) The phosphorescent dopant represented by the general formula (1) is preferably represented by the following general formula (2).

In the general formula (2), Ar, R1m, R2m, R1n, R2n, Ra, Rc, na, nc, m, and n are Ar, R1m, R2m, R1n, R2n, Ra, Rc, It is synonymous with na, nc, m and n.

In the general formula (2), the structures of the three ligands coordinated to Ir are not all the same.

The phosphorescent dopants represented by the general formulas (1) and (2) according to the present invention can be synthesized by referring to known methods described in International Publication No. 2006/121811, etc.

(3) The phosphorescent dopant represented by the general formula (3) The phosphorescent dopant represented by the above general formula (1) or (2) is preferably represented by the following general formula (3).

In the general formula (3), R1m, R2m, R1n, R2n, Rc, na, nc, m, and n are R1m, R2m, R1n, R2n, Rc, na, nc, m, and n in the general formula (1). It is synonymous. In General formula (3), Ra is synonymous with Rc in General formula (1).

In the general formula (3), Ra ₃ has the same meaning as Rb and Rc in the general formula (1).

In the general formula (3), nR3 represents an integer of 1 to 5.

In the general formula (3), the structures of the three ligands coordinated to Ir are not all the same.

(4) The phosphorescent dopant represented by the general formula (4) The phosphorescent dopant represented by the above general formula (1) is preferably represented by the following general formula (4).

In the general formula (4), R1m, R2m, R1n, R2n, Ra, Rc, na, nc, m and n are R1m, R2m, R1n, R2n, Ra, Rc, na, nc, general formula (3). It is synonymous with m and n.

In the general formula (4), Ra ₃ has the same meaning as Rb and Rc in the general formula (1).

In the general formula (4), nR3 represents an integer of 1 to 4.

In the general formula (4), X represents O, S, SiRz1Rz2, NRz1, CRz1Rz2, and Rz1 and Rz2 are an alkyl group, an aromatic hydrocarbon ring group, an aromatic heterocyclic group, a non-aromatic hydrocarbon ring group, or Represents a non-aromatic heterocyclic group.

The aromatic hydrocarbon ring group, aromatic heterocyclic group, non-aromatic hydrocarbon ring group or non-aromatic heterocyclic group represented by Rz1 and Rz2 is represented by Ar in the above general formula (1). And monovalent groups derived from an aromatic hydrocarbon ring, an aromatic heterocycle, a non-aromatic hydrocarbon ring, or a non-aromatic hydrocarbon ring.

(5) The phosphorescent dopant represented by the general formula (5) The phosphorescent dopant represented by the above general formula (1) is preferably represented by the following general formula (5).

In the general formula (5), R1m, R2m, R1n, R2n, Ra, Rc, na, nc, m, and n are R1m, R2m, R1n, R2n, Ra, Rc, na, nc, in the general formula (3). It is synonymous with m and n.

In the general formula (5), Ra ₃ have the same meanings as Rb and Rc in formula (1).

In general formula (5), nR3 and X are synonymous with nR3 and X in general formula (4).

In general formulas (1) to (5), a phosphorescent dopant in which m is 1 and n is 2 is particularly preferable because a long lifetime can be obtained.

(6) Specific Examples Specific examples of phosphorescent dopants represented by the general formulas (1) to (5) are shown below, but the present invention is not limited thereto.

(7) Synthesis Example Hereinafter, synthesis examples of the compounds represented by the general formulas (1) to (5) will be described, but the present invention is not limited thereto. Of the specific examples described above, the DP-1 synthesis method will be described below as an example.

DP-1 can be synthesized according to the following scheme.

(Process 1)
A three-headed flask was charged with 5 g of intermediate A, 1.9 g of iridium chloride, 100 ml of ethoxyethanol, and 30 ml of water, and heated and stirred at 100 ° C. for 4 hours in a nitrogen atmosphere.

The precipitated crystals were collected by filtration, and the collected crystals were washed with methanol to obtain 4.5 g of Intermediate B.

(Process 2)
In a three-headed flask, 4.0 g of the intermediate B obtained in Step 1, 2.5 g of acetylacetone, 7 g of potassium carbonate, and 100 ml of ethoxyethanol were placed and heated and stirred at 80 ° C. for 5 hours under a nitrogen atmosphere.

The precipitated crystals were collected by filtration, and the collected crystals were washed with methanol and then washed with water to obtain 2.8 g of Intermediate C.

(Process 3)
In a three-headed flask, 2.8 g of intermediate C obtained in step 2, 1.6 g of intermediate D and 50 ml of ethylene glycol were placed, and the mixture was heated and stirred at 150 ° C. for 7 hours in a nitrogen atmosphere.

The precipitated crystals were collected by filtration, and the collected crystals were washed with methanol and separated and purified by silica gel chromatography to obtain 0.7 g of DP-1.

The structure of Compound Example DP-1 was confirmed by mass spectrum and ¹ H-NMR.

MASS spectrum (ESI): m / z = 1179 [M ⁺ ]
_{^{1 H-NMR (CD 2 Cl}} 2, 400MHz) δ: 7.71 (2H, d, J = 28.3Hz), 7.42 (1H, t, J = 28.3Hz), 7.33-7. 57 (6H, m), 7.34 (4H, t, J = 33.2 Hz), 6.96 (2H, S), 6.81-6.86 (6H, m), 6.69 (2H, d, J = 33.2 Hz), 6.56-6.60 (2H, m), 6.44 (1H, t, J = 23.4 Hz), 6.38 (2H, d, J = 17.6 Hz) ), 6.32 (1H, d, J = 23.4 Hz), 6.16 (2H, d, J = 44.9 Hz), 2.65-2.80 (3H, m, CH of iso-Pr) , 2.29-2.41 (3H, m, CH of iso-Pr), 1.26 (3H, d, J = 26.3Hz, CH 3 of iso-Pr), 1 _{21 (6H, d, J =} 20.5Hz, CH 3 of iso-Pr), 0.92-1.08 (m, 27H, CH 3 of iso-Pr)
(8) Combined use with conventionally known dopants Further, the phosphorescent dopant according to the present invention may be used in combination with a plurality of types of compounds, a combination of phosphorescent dopants having different structures, or a phosphorescent dopant and fluorescence. A combination of dopants may be used.

Here, as a luminescent dopant, the compound as described in the following literature is mentioned as a conventionally well-known luminescent dopant which may be used together with the phosphorescence dopant represented by General formula (1) which concerns on this invention.

Nature 395, 151 (1998), Appl. Phys. Lett. 78, 1622 (2001), Adv. Mater. 19, 739 (2007), Chern. Mater. 17, 3532 (2005), Adv. Mater. 17, 1059 (2005), International Publication No. 2009/100991, International Publication No. 2008/101842, International Publication No. 2003/040257, US Patent Publication No. 2006/835469, US Patent Publication No. 2006/020202194, United States of America. Patent Publication No. 2007/0087321, US Patent Publication No. 2005/0244673, Inorg. Chern. 40, 1704 (2001), Chern. Mater. 16, 2480 (2004), Adv. Mater. 16, 2003 (2004), Angew. Chern. lnt. Ed. 2006, 45, 7800, Appl. Phys. Lett. 86, 153505 (2005), Chern. Lett. 34, 592 (2005), Chern. Commun. 2906 (2005), Inorg. Chern. 42, 1248 (2003), International Publication No. 2009/050290, International Publication No. 2002/015645, International Publication No. 2009/000673, US Patent Publication No. 2002/0034656, US Patent No. 7332232, US Patent Publication No. 2009/0108737, US Patent Publication No. 2009/0039776, US Patent No. 6921915, US Patent No. 6,687,266, US Patent Publication No. 2007/0190359, US Patent Publication No. 2006/0008670, US Patent Publication No. 2009 / No. 065846, U.S. Patent Publication No. 2008/0015355, U.S. Pat. No. 7,250,226, U.S. Pat. No. 7,396,598, U.S. Pat. Publication No. 2006/0263635, U.S. Patent Publication No. 2003/0138657, U.S. Patent Publication. No. 2003/0152802, US Patent No. 7090928, Angew. Chern. lnt. Ed. 47, 1 (2008), Chern. Mater. 18, 5119 (2006), Inorg. Chern. 46, 4308 (2007), Organometallics 23, 3745 (2004), Appl. Phys. Lett. 74, 1361 (1999), International Publication No. 2002/002714, International Publication No. 2006/009024, International Publication No. 2006/056418, International Publication No. 2005/019373, International Publication No. 2005/123873, International Publication No. 200/5123873, International Publication No. 2007/004380, International Publication No. 2006/082742, US Patent Publication No. 2006/0251923, US Publication No. 2005/0260441, US Pat. No. 7,393,599, US Pat. No. 7,534,505. U.S. Patent No. 7,445,855, U.S. Patent Publication No. 2007/0190359, U.S. Patent Publication No. 2008/0297033, U.S. Patent No. 7,338,722, U.S. Patent Publication No. 2002/0134984, U.S. Patent No. 7,279,704, National Patent Publication No. 2006/098120, US Patent Publication No. 2006/103874, International Publication No. 2005/076380, International Publication No. 2010/032663, International Publication No. 2008/140115, International Publication No. 2007/052431; International Publication No. 2011/134013, International Publication No. 2011/157339, International Publication No. 2010/086089, International Publication No. 2009/113646, International Publication No. 2012/020327, International Publication No. 2011/051404, International Publication No. 2011/004639, WO 2011/073149, JP 2012-069737, JP 2011-181303, JP 2009-1114086, JP 2003-81988, JP 2002-302671, JP Open 2 Such as No. 02-363552.

(Host compound (also referred to as light-emitting host or light-emitting host compound)
In the present invention, among the compounds contained in the light emitting layer, the host compound has a mass ratio of 20% or more in the layer, and the phosphorescence quantum yield of phosphorescence emission is 0 at room temperature (25 ° C.). Defined as less than 1 compound. The phosphorescence quantum yield is preferably less than 0.01. Moreover, it is preferable that the mass ratio in the layer is 20% or more among the compounds contained in a light emitting layer.

The light-emitting host that can be used in the present invention is not particularly limited, and compounds conventionally used in organic EL devices can be used. Typically, a carbazole derivative, a triarylamine derivative, an aromatic derivative, a nitrogen-containing heterocyclic compound, a thiophene derivative, a furan derivative, an oligoarylene compound or the like having a basic skeleton, or a carboline derivative or a diazacarbazole derivative (here And the diazacarbazole derivative represents one in which at least one carbon atom of the hydrocarbon ring constituting the carboline ring of the carboline derivative is substituted with a nitrogen atom.

As the known light-emitting host that can be used in the present invention, a compound that has a hole transporting ability and an electron transporting ability, prevents the emission of light from being long-wavelength, and has a high Tg (glass transition temperature) is preferable. .

In the present invention, a conventionally known light emitting host may be used alone, or a plurality of types may be used in combination. By using a plurality of types of light-emitting hosts, the movement of charges can be adjusted, and the organic EL element can be made highly efficient. Moreover, it becomes possible to mix different light emission by using multiple types of the metal complex of this invention used as the said phosphorescence dopant, and / or a conventionally well-known compound, and, thereby, arbitrary luminescent colors can be obtained.

The light emitting host used in the present invention may be a low molecular compound, a high molecular compound having a repeating unit, or a low molecular compound having a polymerizable group such as a vinyl group or an epoxy group (polymerizable light emitting host). Of course, one or more of such compounds may be used. Specific examples of the known light-emitting host include compounds described in the following documents.

JP-A-2001-257076, 2002-308855, 2001-313179, 2002-319491, 2001-357777, 2002-334786, 2002-8860, 2002-334787, 2002-15871, 2002-334788, 2002-43056, 2002-334789, 2002-75645, 2002-338579, 2002-105445, 2002-343568, 2002-141173, 2002-352957, 2002-203683, 2002-363227, 2002-231453, 2003-3165, 2002-234888, 2003-27048, 2002-255934, 2002-260861, 2002-280183, 2002-299060, 2002 -302516, 2002-305083, 2002-305084, 2002-308837, US Patent Publication No. 2003/0175553, US Patent Publication No. 2006/0280965, US Patent Publication No. 2005 / 0112407, US Patent Publication No. 2009/0017330, US Patent Publication No. 2009/0030202, US Patent Publication No. 2005/0238919, International Publication No. 2001/039234, International Publication No. 2009/021126. International Publication No. 2008/056746, International Publication No. 2004/093207, International Publication No. 2005/089025, International Publication No. 2007/063796, International Publication No. 2007/063754, International Publication No. 2004/107822, International Publication No. JP 2005/030900 A, JP 2007-254297 A, EP 2034538, and the like.

Preferred as the light emitting host of the light emitting layer of the organic EL device of the present invention is a compound represented by the following general formula (B) or general formula (E).

In the general formulas (B) and (E), Xa represents O or S, Xb, Xc, Xd and Xe each represents a hydrogen atom, a substituent or a group represented by the following general formula (C), At least one of Xb, Xc, Xd and Xe represents a group represented by the following general formula (C), and at least one of the groups represented by the following general formula (C) is substituted with Ar. A carbazolyl group which may have

General formula (C)
Ar- (L ₄ ) _n- *
In General Formula (C), L ₄ represents a divalent linking group derived from an aromatic hydrocarbon ring or an aromatic heterocyclic ring. n represents an integer of 0 to 3, and when n is 2 or more, the plurality of L ₄ may be the same or different. * Represents a linking site with the general formula (B) or (E). Ar represents a group represented by the following general formula (D).

In the general formula (D), Xf represents N (R ″), O or S, E ₁ to E ₈ represent C (R ″ ₁ ) or N, R ″ and R ″ ₁ are hydrogen atoms, substituents or it represents a linking site with L ₄ in formula (C). * Represents a linking site with L ₄ in the general formula (C).

In the compound represented by the general formula (B), preferably, at least two of Xb, Xc, Xd and Xe are represented by the general formula (C), and more preferably Xc is represented by the general formula (C). And Ar in the general formula (C) represents a carbazolyl group which may have a substituent.

In addition, a compound represented by the following general formula (B ′) is particularly preferably used as a light emitting host of the light emitting layer of the organic EL device of the present invention.

In general formula (B ′), Xa represents O or S, and Xb and Xc each represents a substituent or a group represented by general formula (C).

At least one of Xb and Xc represents the group represented by the general formula (C), and at least one of the groups represented by the general formula (C) has a substituent. Represents a good carbazolyl group.

In the compound represented by the general formula (B ′), preferably, Ar in the general formula (C) represents a carbazolyl group linked to L ₄ in the general formula (C) at the N position.

As a compound represented by the general formula (B) or the general formula (B ′) preferably used as a host compound (also referred to as a light emitting host) of the light emitting layer of the organic EL device of the present invention, International Publication No. 2006/114966. , International Publication No. 2009/086028, International Publication No. 2009/003898, International Publication No. 2012/023947, Japanese Unexamined Patent Publication No. 2008-74939, Japanese Unexamined Patent Publication No. 2012-231146, Japanese Unexamined Patent Publication No. 2007-288035, etc. Compounds.

Hereinafter, specific examples of the compound represented by the general formula (B) or the general formula (B ′) that are preferably used as the light-emitting host of the light-emitting layer of the organic EL device of the present invention will be given, but the present invention is not limited thereto.

《Electron transport layer》
The electron transport layer is made of a material having a function of transporting electrons, and in a broad sense, an electron injection layer and a hole blocking layer are also included in the electron transport layer. The electron transport layer can be provided with a single layer or a plurality of layers.

The electron transport layer only needs to have a function of transmitting electrons injected from the cathode to the light emitting layer, and as a constituent material of the electron transport layer, any one of conventionally known compounds may be selected and used in combination. Is also possible.

Examples of conventionally known materials used for the electron transport layer (hereinafter referred to as electron transport materials) include polycyclic aromatic hydrocarbons such as nitro-substituted fluorene derivatives, diphenylquinone derivatives, thiopyran dioxide derivatives, naphthalene perylene, Heterocyclic tetracarboxylic anhydride, carbodiimide, fluorenylidenemethane derivative, anthraquinodimethane and anthrone derivative, oxadiazole derivative, carboline derivative, or carbon atom of the hydrocarbon ring constituting the carboline ring of the carboline derivative Derivatives having a ring structure in which at least one is substituted with a nitrogen atom, hexaazatriphenylene derivatives, and the like can be mentioned.

Furthermore, in the oxadiazole derivative, a thiadiazole derivative in which the oxygen atom of the oxadiazole ring is substituted with a sulfur atom, and a quinoxaline derivative having a quinoxaline ring known as an electron-withdrawing group can also be used as an electron transport material.

It is also possible to use a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain.

In addition, metal complexes of 8-quinolinol derivatives such as tris (8-quinolinol) aluminum (Alq), tris (5,7-dichloro-8-quinolinol) aluminum, tris (5,7-dibromo-8-quinolinol) aluminum Tris (2-methyl-8-quinolinol) aluminum, tris (5-methyl-8-quinolinol) aluminum, bis (8-quinolinol) zinc (Znq), and the like, and the central metals of these metal complexes are In, Mg, Metal complexes replaced with Cu, Ca, Sn, Ga, or Pb can also be used as the electron transport material.

In addition, metal-free or metal phthalocyanine, or those in which the terminal is substituted with an alkyl group or a sulfonic acid group can also be used as the electron transport material.

Further, inorganic semiconductors such as n-type-Si and n-type-SiC can also be used as the electron transport material.

The thickness of the electron transport layer is not particularly limited, but is usually in the range of 5 nm to 5000 nm, preferably in the range of 5 nm to 200 nm. The electron transport layer may have a single layer structure composed of one or more of the above materials.

Further, an n-type dopant such as a metal compound such as a metal complex or a metal halide may be doped.

Hereinafter, specific examples of conventionally known compounds (electron transport materials) preferably used for forming the electron transport layer of the organic EL device of the present invention include compounds described in the following documents.

US Pat. No. 6,528,187, US Pat. No. 7,230,107, US Patent Publication No. 2005/0025993, US Patent Publication No. 2004/0036077, US Patent Publication No. 2009/0115316, US Patent Publication No. 2009/01101870, US Patent Publication No. 2009/0179554, International Publication No. 2003/060956, International Publication No. 2008/132805, Appl. Phys. Lett. 75, 4 (1999), Appl. Phys. Lett. 79, 449 (2001), Appl. Phys. Lett. 81, 162 (2002), Appl. Phys. Lett. 79,156 (2001), U.S. Patent No. 7964293, U.S. Patent Publication No. 2009/030202, International Publication No. 2004/080975, International Publication No. 2004/063159, International Publication No. 2005/085387, International Publication No. 2006. No. 067931, International Publication No. 2007/085652, International Publication No. 2008/114690, International Publication No. 2009/066942, International Publication No. 2009/066779, International Publication No. 2009/054253, International Publication No. 2011/086935. No., International Publication No. 2010/150593, International Publication No. 2010/047707, EP23111826, JP2010-251675A, JP2009-209133A, JP2009-124114A, JP2008-277810A. Japanese Unexamined Patent Publication No. 2006-156445, Japanese Unexamined Patent Publication No. 2005-340122, Japanese Unexamined Patent Publication No. 2003-45662, Japanese Unexamined Patent Publication No. 2003-31367, Japanese Unexamined Patent Publication No. 2003-282270, International Publication No. WO 2012/115034.

"cathode"
On the other hand, as the cathode, a material having a low work function (4 eV or less) metal (referred to as an electron injecting metal), an alloy, an electrically conductive compound, and a mixture thereof as an electrode material is used. Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, aluminum, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al ₂ O ₃ ) mixtures, indium, lithium / aluminum mixtures, rare earth metals and the like. Among these, from the point of durability against electron injection and oxidation, etc., a mixture of an electron injecting metal and a second metal which is a stable metal having a larger work function than this, for example, a magnesium / silver mixture, A magnesium / aluminum mixture, a magnesium / indium mixture, an aluminum / aluminum oxide (Al ₂ O ₃ ) mixture, a lithium / aluminum mixture and the like are suitable.

The cathode can be produced by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering. The sheet resistance as the cathode is preferably several hundred Ω / □ or less, and the film thickness is usually selected within the range of 10 nm to 5 μm, preferably within the range of 50 to 200 nm.

In addition, in order to transmit the emitted light, if either one of the anode or the cathode of the organic EL element is transparent or translucent, the emission luminance is improved, which is convenient.

In addition, after forming the above metal on the cathode with a film thickness in the range of 1 to 20 nm, a transparent transparent or semi-transparent cathode is prepared by forming a conductive transparent material mentioned in the description of the anode described later on the cathode. By applying this, an element in which both the anode and the cathode are transmissive can be manufactured.

<< Injection layer: electron injection layer (cathode buffer layer), hole injection layer >>
The injection layer is provided as necessary, and there are an electron injection layer and a hole injection layer, and as described above, it exists between the anode and the light emitting layer or the hole transport layer and between the cathode and the light emitting layer or the electron transport layer. May be.

An injection layer is a layer provided between an electrode and an organic layer in order to reduce drive voltage and improve light emission luminance. “Organic EL element and its forefront of industrialization (issued by NTT Corporation on November 30, 1998) ) ”, Chapter 2,“ Electrode Materials ”(pages 123 to 166), which has a hole injection layer (anode buffer layer) and an electron injection layer (cathode buffer layer).

The details of the anode buffer layer (hole injection layer) are described in JP-A-9-45479, JP-A-9-260062, JP-A-8-288069 and the like. As a specific example, copper phthalocyanine is used. Representative phthalocyanine buffer layer, hexaazatriphenylene derivative buffer layer, oxide buffer layer typified by vanadium oxide, amorphous carbon buffer layer, polyaniline as described in JP-T-2003-519432 and JP-A-2006-135145 Examples thereof include a polymer buffer layer using a conductive polymer such as (emeraldine) and polythiophene, and an orthometalated complex layer typified by a tris (2-phenylpyridine) iridium complex.

The details of the cathode buffer layer (electron injection layer) are described in JP-A-6-325871, JP-A-9-17574, JP-A-10-74586, and the like. Specifically, strontium, aluminum, etc. Metal buffer layer typified by, alkali metal compound buffer layer typified by lithium fluoride and potassium fluoride, alkaline earth metal compound buffer layer typified by magnesium fluoride and cesium fluoride, typified by aluminum oxide Examples thereof include an oxide buffer layer. The buffer layer (injection layer) is preferably a very thin film, and the film thickness is preferably in the range of 0.1 nm to 5 μm, although it depends on the material.

<Blocking layer: hole blocking layer, electron blocking layer>
As described above, the blocking layer is provided as necessary in addition to the basic constituent layer of the organic compound thin film. For example, it is described in JP-A Nos. 11-204258 and 11-204359, and “Organic EL elements and the forefront of industrialization (published by NTT Corporation on November 30, 1998)” on page 237. There is a hole blocking (hole blocking) layer.

The hole blocking layer has a function of an electron transport layer in a broad sense, and is made of a hole blocking material having a function of transporting electrons and a very small ability to transport holes. By blocking the holes, the probability of recombination of electrons and holes can be improved.

Moreover, the structure of the electron transport layer described above can be used as a hole blocking layer according to the present invention, if necessary.

The hole blocking layer of the organic EL device of the present invention is preferably provided adjacent to the light emitting layer.

The hole blocking layer includes a carbazole derivative, a carboline derivative, a diazacarbazole derivative (the diazacarbazole derivative is a nitrogen atom in which any one of carbon atoms constituting the carboline ring is mentioned as the host compound described above. It is preferable to contain (represented by).

In the present invention, when a plurality of light emitting layers having different light emission colors are provided, the light emitting layer having the shortest wavelength of light emission is preferably closest to the anode among all the light emitting layers. In this case, it is preferable to additionally provide a hole blocking layer between the shortest wave layer and the light emitting layer next to the anode next to the anode. Furthermore, it is preferable that 50% by mass or more of the compound contained in the hole blocking layer provided at the position has an ionization potential of 0.3 eV or more larger than the host compound of the shortest wave emitting layer.

The ionization potential is defined by the energy required to emit electrons at the HOMO (highest occupied orbital) level of the compound to the vacuum level, and can be determined by, for example, the following method.

(1) Using Gaussian 98 (Gaussian 98, Revision A.11.4, MJ Frisch, et al, Gaussian, Inc., Pittsburgh PA, 2002.), a molecular orbital calculation software manufactured by Gaussian, USA As a value (eV unit converted value) calculated by performing structure optimization using B3LYP / 6-31G *. This calculation value is effective because the correlation between the calculation value obtained by this method and the experimental value is high.

(2) The ionization potential can also be obtained by a method of directly measuring by photoelectron spectroscopy. For example, a low energy electron spectrometer “Model AC-1” manufactured by Riken Keiki Co., Ltd. or a method known as ultraviolet photoelectron spectroscopy can be suitably used.

On the other hand, the electron blocking layer has a function of a hole transport layer in a broad sense, and is made of a material having a function of transporting holes while having a remarkably small ability to transport electrons. The probability of recombination of electrons and holes can be improved by blocking.

Moreover, the structure of the hole transport layer described later can be used as an electron blocking layer as necessary. The film thickness of the hole blocking layer and the electron transport layer is preferably in the range of 3 to 100 nm, more preferably in the range of 5 to 30 nm.

《Hole transport layer》
The hole transport layer is made of a hole transport material having a function of transporting holes, and in a broad sense, a hole injection layer and an electron blocking layer are also included in the hole transport layer. The hole transport layer can be provided as a single layer or a plurality of layers.

The hole transport material has any of hole injection or transport and electron barrier properties, and may be either organic or inorganic. For example, triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives and pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, Examples thereof include stilbene derivatives, silazane derivatives, aniline copolymers, and conductive polymer oligomers, particularly thiophene oligomers.

Further, azatriphenylene derivatives as described in JP-T-2003-519432 and JP-A-2006-135145 can also be used as the hole transport material.

As the hole transport material, those described above can be used, but it is preferable to use a porphyrin compound, an aromatic tertiary amine compound and a styrylamine compound, particularly an aromatic tertiary amine compound.

Representative examples of aromatic tertiary amine compounds and styrylamine compounds include N, N, N ′, N′-tetraphenyl-4,4′-diaminophenyl; N, N′-diphenyl-N, N′— Bis (3-methylphenyl)-[1,1′-biphenyl] -4,4′-diamine (TPD); 2,2-bis (4-di-p-tolylaminophenyl) propane; 1,1-bis (4-di-p-tolylaminophenyl) cyclohexane; N, N, N ′, N′-tetra-p-tolyl-4,4′-diaminobiphenyl; 1,1-bis (4-di-p-tolyl) Aminophenyl) -4-phenylcyclohexane; bis (4-dimethylamino-2-methylphenyl) phenylmethane; bis (4-di-p-tolylaminophenyl) phenylmethane; N, N'-diphenyl-N, N ' Di (4-methoxyphenyl) -4,4'-diaminobiphenyl; N, N, N ', N'-tetraphenyl-4,4'-diaminodiphenyl ether; 4,4'-bis (diphenylamino) quadriphenyl N, N, N-tri (p-tolyl) amine; 4- (di-p-tolylamino) -4 '-[4- (di-p-tolylamino) styryl] stilbene; 4-N, N-diphenylamino -(2-diphenylvinyl) benzene; 3-methoxy-4'-N, N-diphenylaminostilbene; N-phenylcarbazole, and also two fused aromatic rings described in US Pat. No. 5,061,569 In the molecule, for example, 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (α-NPD), JP-A-4-308688 4,4 ', 4 "-tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine (MTDATA ) And the like.

Further, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used.

Also, inorganic compounds such as p-type-Si and p-type-SiC can be used as the hole injection material and the hole transport material.

Also, JP-A-11-251067, J. Org. Huang et. al. A so-called p-type hole transport material as described in a book (Applied Physics Letters 80 (2002), p. 139) can also be used. In the present invention, these materials are preferably used because a light-emitting element with higher efficiency can be obtained.

The hole transport layer is formed by thinning the hole transport material by a known method such as a vacuum deposition method, a spin coating method, a casting method, a printing method including an ink jet method, or an LB method. Can do.

The thickness of the hole transport layer is not particularly limited, but is usually in the range of 5 nm to 5 μm, preferably in the range of 5 nm to 200 nm. This hole transport layer may have a single layer structure composed of one or more of the above materials.

It is also possible to use a hole transport layer having a high p property doped with impurities. Examples thereof include JP-A-4-297076, JP-A-2000-196140, and JP-A-2001-102175. Appl. Phys. 95, 5773 (2004), and the like.

In the present invention, it is preferable to use a hole transport layer having such a high p property because a device with lower power consumption can be produced.

"anode"
As the anode in the organic EL element, an electrode material made of a metal, an alloy, an electrically conductive compound, or a mixture thereof having a high work function (4 eV or more) is preferably used. Specific examples of such electrode substances include metals such as Au, and conductive transparent materials such as CuI, indium tin oxide (ITO), SnO ₂ , and ZnO.

Alternatively, an amorphous material such as IDIXO (In ₂ O ₃ —ZnO) capable of forming a transparent conductive film may be used. For the anode, a thin film may be formed by depositing these electrode materials by a method such as vapor deposition or sputtering, and a pattern having a desired shape may be formed by a photolithography method, or when pattern accuracy is not required (about 100 μm or more) ), A pattern may be formed through a mask having a desired shape when the electrode material is deposited or sputtered.

Alternatively, when a material that can be applied such as an organic conductive compound is used, a wet film forming method such as a printing method or a coating method can be used. When light emission is extracted from the anode, it is desirable that the transmittance be greater than 10%, and the sheet resistance as the anode is preferably several hundred Ω / □ or less. Further, although depending on the material, the film thickness is usually selected within the range of 10 nm to 1000 nm, preferably within the range of 10 nm to 200 nm.

《Support substrate》
The support substrate (hereinafter also referred to as a substrate, substrate, substrate, support, etc.) that can be used in the organic EL device of the present invention is not particularly limited in the type of glass, plastic, etc., and is transparent. Or opaque. When extracting light from the support substrate side, the support substrate is preferably transparent. Examples of the material of the transparent support substrate that is preferably used include glass, quartz, and a transparent resin film. A particularly preferable support substrate is a resin film capable of giving flexibility to the organic EL element.

Examples of the resin for the resin film include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyethylene, polypropylene, cellophane, cellulose diacetate, cellulose triacetate (TAC), cellulose acetate butyrate, and cellulose acetate propio. Cellulose esters such as nate (CAP), cellulose acetate phthalate, cellulose nitrate or derivatives thereof, polyvinylidene chloride, polyvinyl alcohol, polyethylene vinyl alcohol, syndiotactic polystyrene, polycarbonate, norbornene resin, polymethylpentene, polyether ketone , Polyimide, polyethersulfone (PES), polyphenylene sulfide, polysulfur Cycloolefins such as amines, polyetherimide, polyetherketoneimide, polyamide, fluororesin, nylon, polymethylmethacrylate, acrylic or polyarylate, arton (trade name, manufactured by JSR) or appel (trade name, manufactured by Mitsui Chemicals) Based resins and the like.

The surface of the resin film may be formed with an inorganic film, an organic film, or a hybrid film of both, and the water vapor permeability (25 ± 0.5 ° C.) measured by a method according to JIS K 7129-1992. oxygen relative humidity (90 ± 2)% RH) is preferably a barrier film of 0.01g ^/ (m 2 · 24h) or less, and still more, as measured by the method based on JIS K 7126-1987 A high barrier film having a permeability of 10 ⁻³ ml / (m ² · 24 h · atm) or less and a water vapor permeability of 10 ⁻⁵ g / (m ² · 24 h) or less is preferable.

The material for forming the barrier film may be any material that has a function of suppressing the entry of elements that cause deterioration of elements such as moisture and oxygen. For example, silicon oxide, silicon dioxide, silicon nitride, and the like can be used. Further, in order to improve the brittleness of the film, it is more preferable to have a laminated structure of these inorganic layers and organic material layers. Although there is no restriction | limiting in particular about the lamination | stacking order of an inorganic layer and an organic layer, It is preferable to laminate | stack both alternately several times.

The method for forming the barrier film is not particularly limited. For example, vacuum deposition, sputtering, reactive sputtering, molecular beam epitaxy, cluster ion beam, ion plating, plasma polymerization, atmospheric pressure plasma polymerization A plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, or the like can be used, but an atmospheric pressure plasma polymerization method as described in JP-A-2004-68143 is particularly preferable.

Examples of the opaque support substrate include metal plates such as aluminum and stainless steel, films, opaque resin substrates, ceramic substrates, and the like.

The luminous efficiency of the organic EL device of the present invention at room temperature (also referred to as external extraction quantum efficiency) is preferably 1% or more, and more preferably 5% or more.

Here, the external extraction quantum efficiency (%) = the number of photons emitted to the outside of the organic EL element / the number of electrons sent to the organic EL element × 100.

Also, a hue improvement filter such as a color filter may be used in combination, or a color conversion filter that converts the emission color from the organic EL element into multiple colors using a phosphor may be used in combination. In the case of using a color conversion filter, the λmax of light emission of the organic EL element is preferably 480 nm or less.

<< Method for producing organic EL element >>
As an example of a method for producing an organic EL device, a device comprising an anode / hole injection layer / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode buffer layer (electron injection layer) / cathode Will be described.

First, a thin film made of a desired electrode material, for example, an anode material, is formed on a suitable substrate so as to have a film thickness of 1 μm or less, preferably in the range of 10 to 200 nm, thereby producing an anode.

Next, a thin film containing an organic compound such as a hole injection layer, a hole transport layer, a light emitting layer, a hole blocking layer, an electron transport layer, or a cathode buffer layer, which is an element material, is formed thereon.

As a method for forming a thin film, for example, a thin film can be formed by a vacuum deposition method, a wet method (also referred to as a wet process), or the like.

Wet methods include spin coating, casting, die coating, blade coating, roll coating, ink jet, printing, spray coating, curtain coating, and LB, but precise thin films can be formed. In view of high productivity, a method having high suitability for a roll-to-roll method such as a die coating method, a roll coating method, an ink jet method, or a spray coating method is preferable. Different film formation methods may be applied for each layer.

Examples of the liquid medium for dissolving or dispersing the organic EL material according to the present invention include ketones such as methyl ethyl ketone and cyclohexanone, fatty acid esters such as ethyl acetate, halogenated hydrocarbons such as dichlorobenzene, toluene, xylene, and mesitylene. Aromatic hydrocarbons such as cyclohexylbenzene, aliphatic hydrocarbons such as cyclohexane, decalin, and dodecane, and organic solvents such as DMF and DMSO can be used.

Further, as a dispersion method, it can be dispersed by a dispersion method such as ultrasonic wave, high shearing force dispersion or media dispersion.

After these layers are formed, a thin film made of a cathode material is formed thereon so as to have a thickness of 1 μm or less, preferably in the range of 50 to 200 nm, and a desired organic EL device can be obtained by providing a cathode. .

Also, the cathode, cathode buffer layer, electron transport layer, hole blocking layer, light emitting layer, hole transport layer, hole injection layer, and anode can be formed in the reverse order.

When the organic EL device of the present invention is produced by a vacuum deposition method, it is preferable to produce from the hole injection layer to the cathode consistently by a single vacuum drawing, but even if it is taken out halfway and subjected to different film formation methods. I do not care. At that time, it is preferable to perform the work in a dry inert gas atmosphere.

<Sealing>
As a sealing means used in the present invention, for example, a sealing member such as a glass cover as shown in FIG. 6 and a glass substrate for sealing or a support substrate for an organic EL element are bonded with an adhesive. Can be mentioned.

The sealing member may be disposed so as to cover the display area of the organic EL element, and may be a concave plate shape or a flat plate shape. Further, transparency and electrical insulation are not particularly limited.

Specific examples include a glass plate, a polymer plate / film, and a metal plate / film. Examples of the glass plate include soda-lime glass, barium / strontium-containing glass, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass, and quartz.

Also, examples of the polymer plate include those formed from polycarbonate, acrylic, polyethylene terephthalate, polyether sulfide, polysulfone and the like.

Examples of the metal plate include those made of one or more metals or alloys selected from the group consisting of stainless steel, iron, copper, aluminum, magnesium, nickel, zinc, chromium, titanium, molybdenum, silicon, germanium, and tantalum.

In the present invention, a polymer film and a metal film can be preferably used because the element can be thinned.

Furthermore, the polymer film has an oxygen permeability measured by a method according to JIS K 7126-1987 of 1 × 10 ⁻³ ml / (m ² · 24 h · atm) or less, and a method according to JIS K 7129-1992. It is preferable that the water vapor permeability (25 ± 0.5 ° C., relative humidity (90 ± 2)% RH) measured in (1) is 1 × 10 ⁻³ g / (m ² · 24 h) or less.

For processing the sealing member into a concave shape, sandblasting, chemical etching, or the like is used.

Specific examples of the adhesive include photocuring and thermosetting adhesives having reactive vinyl groups of acrylic acid oligomers and methacrylic acid oligomers, and moisture curing adhesives such as 2-cyanoacrylates. be able to. Moreover, heat | fever and chemical curing types (two-component mixing), such as an epoxy type, can be mentioned. Moreover, hot-melt type polyamide, polyester, and polyolefin can be mentioned. Moreover, a cationic curing type ultraviolet curing epoxy resin adhesive can be mentioned.

In addition, since an organic EL element may deteriorate by heat processing, what can be adhesively cured from room temperature to 80 ° C. is preferable. A desiccant may be dispersed in the adhesive. Application | coating of the adhesive agent to a sealing part may use commercially available dispenser, and may print like screen printing.

In addition, it is also preferable that the electrode and the organic layer are coated on the outside of the electrode facing the support substrate with the organic layer interposed therebetween, and an inorganic or organic layer is formed in contact with the support substrate to form a sealing film. . In this case, the material for forming the film may be any material that has a function of suppressing intrusion of elements that cause deterioration of elements such as moisture and oxygen. For example, silicon oxide, silicon dioxide, silicon nitride, or the like may be used. it can.

Furthermore, in order to improve the brittleness of the film, it is preferable to have a laminated structure of these inorganic layers and layers made of organic materials. The method for forming these films is not particularly limited. For example, vacuum deposition, sputtering, reactive sputtering, molecular beam epitaxy, cluster ion beam, ion plating, plasma polymerization, atmospheric pressure plasma A combination method, a plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, or the like can be used.

In the gap between the sealing member and the display area of the organic EL element, an inert gas such as nitrogen or argon, or an inert liquid such as fluorinated hydrocarbon or silicon oil can be injected in the gas phase and liquid phase. preferable. A vacuum is also possible. Moreover, a hygroscopic compound can also be enclosed inside.

Examples of the hygroscopic compound include metal oxides (for example, sodium oxide, potassium oxide, calcium oxide, barium oxide, magnesium oxide, aluminum oxide) and sulfates (for example, sodium sulfate, calcium sulfate, magnesium sulfate, cobalt sulfate). Etc.), metal halides (eg calcium chloride, magnesium chloride, cesium fluoride, tantalum fluoride, cerium bromide, magnesium bromide, barium iodide, magnesium iodide etc.), perchloric acids (eg perchloric acid) Barium, magnesium perchlorate, and the like), and anhydrous salts are preferably used in sulfates, metal halides, and perchloric acids.

《Protective film, protective plate》
In order to increase the mechanical strength of the element, a protective film or a protective plate may be provided on the outer side of the sealing film on the side facing the support substrate with the organic layer interposed therebetween or on the sealing film. In particular, when the sealing is performed by the sealing film, the mechanical strength is not necessarily high, and thus it is preferable to provide such a protective film and a protective plate. As a material that can be used for this, the glass plate, polymer plate / film, metal plate / film, etc., mentioned as specific examples of the sealing member can be used, but the polymer film is light and thin. Is preferably used.

《Light extraction》
The organic EL element emits light inside a layer having a refractive index higher than that of air (refractive index is about 1.7 to 2.1) and can extract only about 15% to 20% of the light generated in the light emitting layer. It is generally said. This is because light incident on the interface (interface between the transparent substrate and air) at an angle θ greater than the critical angle causes total reflection and cannot be taken out of the device, or between the transparent electrode or light emitting layer and the transparent substrate. This is because the light undergoes total reflection between the light and the light, and the light is guided through the transparent electrode or the light emitting layer.

As a technique for improving the light extraction efficiency, for example, a method of forming irregularities on the surface of the transparent substrate to prevent total reflection at the interface between the transparent substrate and the air (US Pat. No. 4,774,435), condensing on the substrate. A method of improving the efficiency by imparting a property (Japanese Patent Laid-Open No. 63-314795), a method of forming a reflective surface on the side surface of the element (Japanese Patent Laid-Open No. 1-220394), and between the substrate and the light emitter A method of forming an antireflection film by introducing a flat layer having an intermediate refractive index (Japanese Patent Laid-Open No. 62-172691), and introducing a flat layer having a lower refractive index than the substrate between the substrate and the light emitter. A method (Japanese Patent Laid-Open No. 2001-202827), a method of forming a diffraction grating between any one of the substrate, the transparent electrode layer and the light emitting layer (including between the substrate and the outside) (Japanese Patent Laid-Open No. 11-283951), and the like. is there.

In the present invention, these methods can be used in combination with the organic EL device of the present invention. However, a method of introducing a flat layer having a lower refractive index than the substrate between the substrate and the light emitter, or a substrate, transparent A method of forming a diffraction grating between any layers of the electrode layer and the light emitting layer (including between the substrate and the outside) can be suitably used.

In the present invention, by combining these means, it is possible to obtain an element having higher brightness or durability.

When a medium with a low refractive index is formed between the transparent electrode and the transparent substrate with a thickness longer than the wavelength of light, the light extracted from the transparent electrode has a higher extraction efficiency to the outside as the refractive index of the medium is lower. .

Examples of the low refractive index layer include aerogel, porous silica, magnesium fluoride, and a fluorine-based polymer. Since the refractive index of the transparent substrate is generally in the range of 1.5 to 1.7, the low refractive index layer preferably has a refractive index of about 1.5 or less. Further, it is preferably 1.35 or less.

Also, the thickness of the low refractive index medium is preferably at least twice the wavelength in the medium. This is because the effect of the low refractive index layer is diminished when the thickness of the low refractive index medium is about the wavelength of light and the electromagnetic wave that has exuded by evanescent enters the substrate.

The method of introducing a diffraction grating into an interface or any medium that causes total reflection is characterized by a high effect of improving light extraction efficiency. This method uses the property that the diffraction grating can change the direction of light to a specific direction different from refraction by so-called Bragg diffraction such as first-order diffraction or second-order diffraction. Light that cannot be emitted due to total internal reflection, etc. is diffracted by introducing a diffraction grating in any layer or medium (in the transparent substrate or transparent electrode), and the light is emitted outside. I want to take it out.

It is desirable that the diffraction grating to be introduced has a two-dimensional periodic refractive index. This is because light emitted from the light-emitting layer is randomly generated in all directions, so in a general one-dimensional diffraction grating having a periodic refractive index distribution only in a certain direction, only light traveling in a specific direction is diffracted. Therefore, the light extraction efficiency does not increase so much.

By making the refractive index distribution a two-dimensional distribution, the light traveling in all directions is diffracted, and the light extraction efficiency increases.

As described above, the position where the diffraction grating is introduced may be in any interlayer or medium (in the transparent substrate or in the transparent electrode), but is preferably in the vicinity of the organic light emitting layer where light is generated.

At this time, the period of the diffraction grating is preferably in the range of about 1/2 to 3 times the wavelength of light in the medium.

The arrangement of the diffraction grating is preferably two-dimensionally repeated such as a square lattice, a triangular lattice, or a honeycomb lattice.

<Condenser sheet>
The organic EL device of the present invention can be processed on the light extraction side of the substrate, for example, by providing a microlens array-like structure, or combined with a so-called condensing sheet, for example, in a specific direction, for example, the device light emitting surface. On the other hand, the brightness | luminance in a specific direction can be raised by condensing in a front direction.

As an example of the microlens array, a quadrangular pyramid having a side of 30 μm and an apex angle of 90 degrees is arranged two-dimensionally on the light extraction side of the substrate. One side is preferably within a range of 10 μm to 100 μm. If it becomes smaller than this, the effect of diffraction will generate | occur | produce and color, and when too large, an organic EL element will become thick and is unpreferable.

As the condensing sheet, it is possible to use, for example, a sheet that has been put to practical use in an LED backlight of a liquid crystal display device. As such a sheet, for example, a brightness enhancement film (BEF) manufactured by Sumitomo 3M Limited can be used.

As the shape of the prism sheet, for example, the base material may be formed by forming a △ -shaped stripe having a vertex angle of 90 degrees and a pitch of 50 μm, or the vertex angle is rounded and the pitch is changed randomly. Other shapes may be used.

Further, in order to control the light emission angle from the light emitting element, a light diffusion plate / film may be used in combination with the light collecting sheet. For example, a diffusion film (light-up) manufactured by Kimoto Co., Ltd. can be used.

<Application>
The organic EL element of the present invention can be used as a display device, a display, and various light emission sources. For example, lighting devices (home lighting, interior lighting), clock and liquid crystal backlights, billboard advertisements, traffic lights, light sources of optical storage media, light sources of electrophotographic copying machines, light sources of optical communication processors, light Although the light source of a sensor etc. are mentioned, It is not limited to this, It can use effectively for the use as a backlight of a liquid crystal display device, and an illumination light source especially.

In the organic EL device of the present invention, patterning may be performed by a metal mask, an ink jet printing method, or the like during film formation, if necessary. In the case of patterning, only the electrode may be patterned, the electrode and the light emitting layer may be patterned, or the entire layer of the element may be patterned. In the fabrication of the element, a conventionally known method is used. Can do.

The light emission color of the organic EL device of the present invention and the compound according to the present invention is shown in FIG. 4.16 on page 108 of “New Color Science Handbook” (edited by the Japan Color Society, University of Tokyo Press, 1985). It is determined by the color when the result measured with a total of CS-1000 (manufactured by Konica Minolta Optics Co., Ltd.) is applied to the CIE chromaticity coordinates.

When the organic EL element of the present invention is a white element, white means that the chromaticity in the CIE1931 color system at 1000 cd / m ² is X when the 2 ° viewing angle front luminance is measured by the above method. = 0.33 ± 0.07 and Y = 0.33 ± 0.1.

<Display device>
A display device that can be manufactured using the organic EL element of the present invention will be described. The display device comprises the organic EL element of the present invention. The display device may be single color or multicolor, but here, the multicolor display device will be described.

In the case of a multicolor display device, a shadow mask is provided only at the time of forming a light emitting layer, and a film can be formed on one surface by a vapor deposition method, a cast method, a spin coat method, an inkjet method, a printing method, or the like.

In the case of patterning only the light emitting layer, the method is not limited, but is preferably a vapor deposition method, an inkjet method, a spin coating method, or a printing method.

The configuration of the organic EL element included in the display device is selected from the above-described configuration examples of the organic EL element as necessary.

Moreover, the manufacturing method of an organic EL element is as having shown in the one aspect | mode of manufacture of said organic EL element.

When a DC voltage is applied to the multicolor display device thus obtained, light emission can be observed by applying a voltage in the range of 2 to 40 V with the positive polarity of the anode and the negative polarity of the cathode. Further, even when a voltage is applied with the opposite polarity, no current flows and no light emission occurs. Further, when an AC voltage is applied, light is emitted only when the anode is in the + state and the cathode is in the-state. The alternating current waveform to be applied may be arbitrary.

The multicolor display device can be used as a display device, a display, and various light sources. In a display device or display, full-color display is possible by using three types of organic EL elements that emit blue, red, and green light.

Display devices and displays include televisions, personal computers, mobile devices, AV devices, teletext displays, information displays in automobiles, and the like. In particular, it may be used as a display device for reproducing still images and moving images, and the driving method when used as a display device for reproducing moving images may be either a simple matrix (passive matrix) method or an active matrix method.

Light sources include home lighting, interior lighting, clock and liquid crystal backlights, billboard advertisements, traffic lights, light sources for optical storage media, light sources for electrophotographic copying machines, light sources for optical communication processors, light sources for optical sensors, etc. The present invention is not limited to these examples.

Hereinafter, an example of a display device having the organic EL element of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic view showing an example of a display device composed of organic EL elements. It is a schematic diagram of a display such as a mobile phone that displays image information by light emission of an organic EL element.

The display 1 includes a display unit A having a plurality of pixels, a control unit B that performs image scanning of the display unit A based on image information, and the like.

The control unit B is electrically connected to the display unit A, and sends a scanning signal and an image data signal to each of a plurality of pixels based on image information from the outside, and the pixels for each scanning line respond to the image data signal by the scanning signal. The image information is sequentially emitted to scan the image and display the image information on the display unit A.

FIG. 2 is a schematic diagram of the display unit A.

The display unit A has a wiring unit including a plurality of scanning lines 5 and data lines 6 and a plurality of pixels 3 on the substrate. The main members of the display unit A will be described below.

FIG. 2 shows a case where the light emitted from the pixel 3 is extracted in the direction of the white arrow (downward).

The scanning line 5 and the plurality of data lines 6 in the wiring portion are each made of a conductive material, and the scanning lines 5 and the data lines 6 are orthogonal to each other in a grid pattern and are connected to the pixels 3 at the orthogonal positions (details are illustrated). Not)

When the scanning signal is applied from the scanning line 5, the pixel 3 receives the image data signal from the data line 6 and emits light according to the received image data.

A full color display can be achieved by appropriately arranging pixels in the red region, the green region, and the blue region on the same substrate.

Next, the light emission process of the pixel will be described. FIG. 3 is a schematic diagram of a pixel.

The pixel includes an organic EL element 10, a switching transistor 11, a driving transistor 12, a capacitor 13, and the like. A full color display can be performed by using red, green, and blue light emitting organic EL elements as the organic EL elements 10 in a plurality of pixels, and juxtaposing them on the same substrate.

3, an image data signal is applied from the control unit B to the drain of the switching transistor 11 via the data line 6. When a scanning signal is applied from the control unit B to the gate of the switching transistor 11 via the scanning line 5, the driving of the switching transistor 11 is turned on, and the image data signal applied to the drain is supplied to the capacitor 13 and the driving transistor 12. Is transmitted to the gate.

By transmitting the image data signal, the capacitor 13 is charged according to the potential of the image data signal, and the drive transistor 12 is turned on. The drive transistor 12 has a drain connected to the power supply line 7 and a source connected to the electrode of the organic EL element 10, and the power supply line 7 connects to the organic EL element 10 according to the potential of the image data signal applied to the gate. Current is supplied.

When the scanning signal moves to the next scanning line 5 by the sequential scanning of the control unit B, the driving of the switching transistor 11 is turned off. However, since the capacitor 13 holds the charged potential of the image data signal even if the driving of the switching transistor 11 is turned off, the driving of the driving transistor 12 is kept on and the next scanning signal is applied. Until then, the light emission of the organic EL element 10 continues. When the scanning signal is next applied by sequential scanning, the driving transistor 12 is driven according to the potential of the next image data signal synchronized with the scanning signal, and the organic EL element 10 emits light.

That is, the light emission of the organic EL element 10 is performed by providing the switching transistor 11 and the drive transistor 12 which are active elements with respect to the organic EL element 10 of each of the plurality of pixels. It is carried out. Such a light emitting method is called an active matrix method.

Here, the light emission of the organic EL element 10 may be light emission of a plurality of gradations by a multi-value image data signal having a plurality of gradation potentials, or by turning on / off a predetermined light emission amount by a binary image data signal. Good. The potential of the capacitor 13 may be held continuously until the next scanning signal is applied, or may be discharged immediately before the next scanning signal is applied.

In the present invention, not only the active matrix method described above, but also a passive matrix light emission drive in which an organic EL element emits light according to a data signal only when a scanning signal is scanned.

FIG. 4 is a schematic view of a passive matrix display device. In FIG. 4, a plurality of scanning lines 5 and a plurality of image data lines 6 are provided in a lattice shape so as to face each other with the pixel 3 interposed therebetween.

When the scanning signal of the scanning line 5 is applied by sequential scanning, the pixel 3 connected to the applied scanning line 5 emits light according to the image data signal.

In the passive matrix method, there is no active element in the pixel 3, and the manufacturing cost can be reduced.

《Lighting device》
The lighting device of the present invention will be described. The illuminating device of this invention has the said organic EL element.

The organic EL element of the present invention may be used as an organic EL element having a resonator structure. The purpose of use of the organic EL element having such a resonator structure is as follows. The light source of a machine, the light source of an optical communication processing machine, the light source of a photosensor, etc. are mentioned, However, It is not limited to these. Moreover, you may use for the said use by making a laser oscillation.

Further, the organic EL element of the present invention may be used as a kind of lamp for illumination or exposure light source, a projection device for projecting an image, or a display for directly viewing a still image or a moving image. It may be used as a device (display).

The drive method when used as a display device for moving image reproduction may be either a simple matrix (passive matrix) method or an active matrix method. Alternatively, it is possible to produce a full-color display device by using two or more organic EL elements of the present invention having different emission colors.

Also, the organic EL element of the present invention can be an organic EL element that emits substantially white light as a lighting device. An organic EL element has a plurality of light emitting materials, and a plurality of light emission colors can be emitted simultaneously to obtain white light emission by color mixing. As a combination of a plurality of emission colors, those containing the three emission maximum wavelengths of the three primary colors of red, green and blue may be used, or two emission using the complementary colors such as blue and yellow, blue green and orange, etc. It may contain a maximum wavelength.

In addition, a combination of light emitting materials for obtaining a plurality of emission colors is a combination of a plurality of phosphorescent or fluorescent light emitting materials, a phosphorescent light emitting material, and light from the light emitting material as excitation light. Any combination with a dye material that emits light may be used, but in the white organic EL device according to the present invention, it is only necessary to mix and mix a plurality of light-emitting dopants.

According to this method, unlike the white organic EL device in which light emitting elements of a plurality of colors are arranged in parallel in an array, the elements themselves are luminescent white.

There is no restriction | limiting in particular as a luminescent material used for a light emitting layer, For example, if it is a backlight in a liquid crystal display element, the phosphorescence dopant which concerns on this invention so that it may adapt to the wavelength range corresponding to CF (color filter) characteristic, and Any one of known luminescent materials may be selected and combined to whiten.

<< One aspect of lighting device >>
One mode of a lighting device including the organic EL element of the present invention will be described.

The non-light emitting surface of the organic EL device of the present invention is covered with a glass cover, a 300 μm thick glass substrate is used as a sealing substrate, and an epoxy photo-curing adhesive (LUX Track LC0629B) is applied, and this is overlaid on the cathode and brought into close contact with the transparent support substrate, irradiated with UV light from the glass substrate side, cured, sealed, and illuminated as shown in FIGS. A device can be formed.

FIG. 5 shows a schematic diagram of the lighting apparatus 101, and the organic EL element of the present invention is covered with a glass cover 102 (in addition, the sealing operation with the glass cover is performed without bringing the organic EL element into contact with the atmosphere. (This was performed in a glove box under a nitrogen atmosphere (in an atmosphere of high-purity nitrogen gas having a purity of 99.999% or more)).

6 shows a cross-sectional view of the lighting device shown in FIG. 5. In FIG. 6, 105 is a cathode, 106 is an organic layer (from the anode side, hole injection layer / hole transport layer / light emitting layer / hole blocking). Layer / electron transport layer / cathode buffer layer (electron injection layer)), 107 indicates a transparent glass substrate with an anode. The glass cover 102 is filled with nitrogen gas 108 and a water catching agent 109 is provided.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "part by mass" or "mass%" is represented.

<< Production of Organic EL Element 1 >>
After a 100 mm × 100 mm × 1.1 mm glass substrate was used as the support substrate, and a substrate (NA Techno Glass NA45) was formed on the glass substrate by depositing 100 nm of ITO (indium tin oxide) as the anode. The glass substrate provided with this ITO transparent electrode was subjected to ultrasonic cleaning with isopropyl alcohol, dried with dry nitrogen gas, and UV ozone cleaning was performed for 5 minutes.

A solution obtained by diluting poly (3,4-ethylenedioxythiophene) -polystyrene sulfonate (PEDOT / PSS, manufactured by HC Starck Co., Ltd., CLEVIO P VP AI 4083) with pure water on this transparent support substrate to 70%. A thin film was formed by spin coating under conditions of 3000 rpm and 30 seconds, and then dried at 200 ° C. for 1 hour to provide a hole injection layer having a thickness of 20 nm.

The transparent support substrate provided with the hole injection layer as described above was fixed to a substrate holder of a commercially available vacuum deposition apparatus, while 200 mg of α-NPD was added as a hole transport material to a resistance heating boat made of molybdenum, and another molybdenum 200 mg of OC-30 as a host compound is put into a resistance heating boat made of 200, 200 mg of ET-8 as an electron transport material is put into another resistance heating boat made of molybdenum, and 100 mg of Comparative 1 as a phosphorescent dopant is put into another resistance heating boat made of molybdenum. And attached to a vacuum deposition apparatus.

Next, the pressure in the vacuum chamber was reduced to 4 × 10 ⁻⁴ Pa, and the heating boat containing α-NPD was energized and heated, and deposited on the hole injection layer at a deposition rate of 0.1 nm / second. A 20 nm hole transport layer was provided.

Further, the heating boat containing OC-30 as the host compound and the heating boat containing Comparative 1 as the phosphorescent dopant were energized and heated, and the deposition rates were 0.1 nm / second and 0.004 nm / second, respectively. A 40 nm-thick luminescent layer was provided by co-evaporation on the hole transport layer. From the vapor deposition rate, the content of the phosphorescent dopant with respect to the content of the host compound is a volume ratio of 4% by volume.

In addition, the value of the volume ratio of the phosphorescent dopant to the host compound when the host compound and the phosphorescent dopant are co-evaporated is the deposition rate (thickness increase rate) when the host compound is vapor-deposited alone under the above-mentioned co-deposition conditions. It means the value of the ratio of the deposition rate (thickness increase rate) when the phosphorescent dopant is deposited alone. Moreover, the volume ratio of the phosphorescent dopant with respect to said host compound is also called a doping rate.

Furthermore, the heating boat containing ET-8 was energized and heated, and deposited on the light emitting layer at a deposition rate of 0.1 nm / second to provide an electron transport layer having a thickness of 30 nm.

Subsequently, lithium fluoride was vapor-deposited to form a cathode buffer layer having a thickness of 0.5 nm, and aluminum was further vapor-deposited to form a cathode having a thickness of 110 nm. Thus, an organic EL element 1 was produced.

In addition, the substrate temperature at the time of vapor deposition of the said positive hole transport layer, the said light emitting layer, the said electron carrying layer, the said cathode buffer layer, and the said cathode was room temperature.

<< Preparation of organic EL elements 2 to 117 >>
In the production of the organic EL element 1, the host compound and phosphorescent dopant in the light emitting layer are changed to the compounds shown in Tables 1, 2 and 3, and the volume ratio (volume%) of the light emitting dopant to the host compound (also referred to as the doping rate). As shown in Tables 1, 2 and 3, organic EL elements 2 to 117 were produced in the same manner except that the co-evaporation was carried out at different deposition rates.

The phosphorescent dopants described in the electron transport material ET-8 and Table 1 are shown below.

<< Evaluation of organic EL elements 1-117 >>
When evaluating the obtained organic EL elements 1 to 117, as shown in FIGS. 5 and 6, the non-light-emitting surface of each organic EL element after fabrication was covered with a glass cover 102, and the light-emitting surface was 300 μm thick. Cover with a glass substrate for sealing 103, apply an epoxy photo-curing adhesive (Luxtrac LC0629B, manufactured by Toagosei Co., Ltd.) as a sealing material, and cure by irradiating with UV light from the side of the glass substrate for sealing. Sealing was performed to manufacture each lighting device. Using the lighting device produced as described above, the organic EL elements 1 to 117 were evaluated by the following evaluation methods. The evaluation results are shown in Tables 1, 2 and 3.

"Evaluation methods"
(1) External extraction quantum efficiency (also referred to as light emission efficiency or efficiency)
The organic EL element is turned on at room temperature (within a range of about 23 to 25 ° C.) under a constant current condition of ^2.5 mA / cm ² , and the emission luminance (L) [cd / m ² ] immediately after the start of lighting is measured. Thus, the external extraction quantum efficiency (η) was calculated.

Here, the measurement of emission luminance was performed using CS-1000 (manufactured by Konica Minolta Optics), and the efficiency was expressed as a relative value where the organic EL element 1 was 100.

(2) Half-life In accordance with the measurement method shown below, half-life (also simply referred to as “life”) was evaluated.

Each organic EL device driven with a constant current at a current giving an initial luminance 1000 cd / ^{m 2,} obtains the time to be 1/2 (500cd / ^{m 2)} of the initial luminance, which was used as a measure of the half-life.

Further, the half life at an initial luminance of 3000 cd / m ² was also evaluated in the same manner.

The half-life was expressed as a relative value with the organic EL element 1 having an initial luminance of 1000 cd / m ² as 100.

The organic EL devices 1 to 13 using the phosphorescent dopant “Comparative 1” shown in Table 1, the organic EL devices 14 to 26 using the phosphorescent dopant “Comparative 2”, and the phosphorescent dopant DP-38 shown in Table 2 were used. The lifetimes of the organic EL elements 40 to 52 and the organic EL elements 53 to 65 using the phosphorescent dopant DP-1 when lighted at an initial luminance of 1000 cd / m ² were plotted against the phosphorescent dopant content. The results are shown in FIG. 7, and the results of plotting the lifetime when lighted at an initial luminance of 3000 cd / m ² against the phosphorescent dopant content are shown in FIG. 8.

From Tables 1 to 3 and FIGS. 7 and 8, the organic EL device of the present invention has significant improvements in both efficiency and half life from the region where the doping rate exceeds 8% by volume compared to the organic EL device of the comparative example. Is recognized. Further, in the organic EL element of the comparative example, when the doping rate is about 15% by volume or more, the light emission efficiency and the half life are significantly reduced, whereas the organic EL element of the present invention has a doping rate of about 35 volume. It can be seen that there is little decrease in power efficiency and half-life to 50%. Furthermore, compared with the organic EL element of the comparative example, in the organic EL element of the present invention, the difference between the half life when lighting at an initial luminance of 1000 cd / m ² and the half life when lighting at an initial luminance of 3000 cd / m ² is small. It can be seen that the lifetime is long even when light is emitted with high luminance.

As described above, an element in which the content of the phosphorescent dopant of the present invention is within the range of 8 to 35% by volume with respect to the host compound is high in luminous efficiency and excellent in luminous stability (lifetime) under high luminance. It turns out that it is an electroluminescent element.

Since the organic EL element of the present invention has a high luminous efficiency and a long lifetime, it can be used for a display device and a lighting device.

DESCRIPTION OF SYMBOLS 1 Display 3 Pixel 5 Scan line 6 Data line 7 Power line 10 Organic EL element 11 Switching transistor 12 Drive transistor 13 Capacitor 101 Illumination device 102 Glass cover 103 Glass substrate for sealing 105 Cathode 106 Organic layer 107 Glass substrate 108 with a transparent anode Nitrogen gas 109 Water trapping agent A Display part B Control part L Light

Claims (6)

1. An organic electroluminescence device in which an organic layer including a light emitting layer is sandwiched between an anode and a cathode, wherein the light emitting layer contains a host compound and a phosphorescent dopant represented by the following general formula (1), An organic electroluminescence device, wherein a content of the phosphorescent dopant in the light emitting layer is in a range of 8 to 35% by volume with respect to a content of the host compound.
   

   

   
   [In General Formula (1), Ring Am, Ring An, Ring Bm and Ring Bn represent a 5-membered or 6-membered aromatic hydrocarbon ring or aromatic heterocycle. Ar represents an aromatic hydrocarbon ring, an aromatic heterocycle, a non-aromatic hydrocarbon ring or a non-aromatic heterocycle. R1m, R2m, R1n and R2n each independently represents an alkyl group having 2 or more carbon atoms, an aromatic hydrocarbon ring group, an aromatic heterocyclic group, a non-aromatic hydrocarbon ring group or a non-aromatic heterocyclic group, Furthermore, you may have a substituent. Each Ra is independently a hydrogen atom, halogen atom, cyano group, alkyl group, alkenyl group, alkynyl group, alkoxy group, amino group, silyl group, arylalkyl group, aryl group, heteroaryl group, non-aromatic hydrocarbon ring Represents a linking group that forms a ring with a group, a non-aromatic heterocyclic group or Ar. Rb and Rc are each independently a hydrogen atom, halogen atom, cyano group, alkyl group, alkenyl group, alkynyl group, alkoxy group, amino group, silyl group, arylalkyl group, aryl group, heteroaryl group, non-aromatic carbonization Represents a hydrogen ring group or a non-aromatic heterocyclic group. Ra, Rb and Rc may further have a substituent. na and nc represent 1 or 2, and nb represents an integer of 1 to 4. m represents 1 or 2. n represents 1 or 2. m + n is 3. Note that the structures of the three ligands coordinated to Ir are not all the same. ]
2. 2. The organic electroluminescence device according to claim 1, wherein the content of the phosphorescent dopant in the light emitting layer is in the range of 16 to 30% by volume with respect to the content of the host compound.
3. 3. The organic electroluminescence device according to claim 1, wherein the phosphorescent dopant represented by the general formula (1) is a phosphorescent dopant represented by the following general formula (2).
   

   

   
   [In General Formula (2), Ar represents an aromatic hydrocarbon ring, an aromatic heterocyclic ring, a non-aromatic hydrocarbon ring or a non-aromatic heterocyclic ring. R1m, R2m, R1n and R2n each independently represents an alkyl group having 2 or more carbon atoms, an aromatic hydrocarbon ring group, an aromatic heterocyclic group, a non-aromatic hydrocarbon ring group or a non-aromatic heterocyclic group, Furthermore, you may have a substituent. Each Ra is independently a hydrogen atom, halogen atom, cyano group, alkyl group, alkenyl group, alkynyl group, alkoxy group, amino group, silyl group, arylalkyl group, aryl group, heteroaryl group, non-aromatic hydrocarbon ring Represents a linking group that forms a ring with a group, a non-aromatic heterocyclic group or Ar. Rc each independently represents a hydrogen atom, a halogen atom, a cyano group, an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an amino group, a silyl group, an arylalkyl group, an aryl group, a heteroaryl group, or a non-aromatic hydrocarbon ring. Represents a group or a non-aromatic heterocyclic group. Ra and Rc may further have a substituent. na and nc represent 1 or 2. m represents 1 or 2. n represents 1 or 2. m + n is 3. Note that the structures of the three ligands coordinated to Ir are not all the same. ]
4. 3. The organic electroluminescent device according to claim 1, wherein the phosphorescent dopant represented by the general formula (1) is a phosphorescent dopant represented by the following general formula (3).
   

   

   
   [In General Formula (3), R1m, R2m, R1n and R2n are each independently an alkyl group having 2 or more carbon atoms, an aromatic hydrocarbon ring group, an aromatic heterocyclic group, a non-aromatic hydrocarbon ring group or It represents a non-aromatic heterocyclic group and may further have a substituent. Ra, Rc and Ra ₃ are each independently a hydrogen atom, halogen atom, cyano group, alkyl group, alkenyl group, alkynyl group, alkoxy group, amino group, silyl group, arylalkyl group, aryl group, heteroaryl group, non- Represents an aromatic hydrocarbon ring group or a non-aromatic heterocyclic group; Ra, Ra ₃ and Rc may further have a substituent. na and nc represent 1 or 2. nR3 represents an integer of 1 to 5. m represents 1 or 2. n represents 1 or 2. m + n is 3. Note that the structures of the three ligands coordinated to Ir are not all the same. ]
5. 3. The organic electroluminescent device according to claim 1, wherein the phosphorescent dopant represented by the general formula (1) is a phosphorescent dopant represented by the following general formula (4).
   

   

   
   [In General Formula (4), R1m, R2m, R1n and R2n each independently represents an alkyl group having 2 or more carbon atoms, an aromatic hydrocarbon ring group, an aromatic heterocyclic group, a non-aromatic hydrocarbon ring group or a non-aromatic group. Represents an aromatic heterocyclic group and may further have a substituent. Ra, Rc and Ra ₃ are each independently a hydrogen atom, halogen atom, cyano group, alkyl group, alkenyl group, alkynyl group, alkoxy group, amino group, silyl group, arylalkyl group, aryl group, heteroaryl group, non- It represents an aromatic hydrocarbon ring group or a non-aromatic heterocyclic group, and may further have a substituent. na and nc represent 1 or 2. nR3 represents an integer of 1 to 4. X represents O, S, SiRz1Rz2, NRz1 or CRz1Rz2. Rz1 and Rz2 represent an alkyl group, an aromatic hydrocarbon ring group, an aromatic heterocyclic group, a non-aromatic hydrocarbon ring group, or a non-aromatic heterocyclic group. m represents 1 or 2. n represents 1 or 2. m + n is 3. ]
6. 3. The organic electroluminescent device according to claim 1, wherein the phosphorescent dopant represented by the general formula (1) is a phosphorescent dopant represented by the following general formula (5).
   

   

   
   [In General Formula (5), R1m, R2m, R1n and R2n each independently represents an alkyl group having 2 or more carbon atoms, an aromatic hydrocarbon ring group, an aromatic heterocyclic group, a non-aromatic hydrocarbon ring group or a non-aromatic group. Represents an aromatic heterocyclic group and may further have a substituent. Ra, Rc and Ra ₃ are each independently a hydrogen atom, halogen atom, cyano group, alkyl group, alkenyl group, alkynyl group, alkoxy group, amino group, silyl group, arylalkyl group, aryl group, heteroaryl group, non- It represents an aromatic hydrocarbon ring group or a non-aromatic heterocyclic group, and may further have a substituent. na and nc represent 1 or 2. nR3 represents an integer of 1 to 4. X represents O, S, SiRz1Rz2, NRz1 or CRz1Rz2. Rz1 and Rz2 represent an alkyl group, an aromatic hydrocarbon ring group, an aromatic heterocyclic group, a non-aromatic hydrocarbon ring group, or a non-aromatic heterocyclic group. m represents 1 or 2. n represents 1 or 2. m + n is 3. ]

Images