JP7173145B2 - thin film, electronic device, organic electroluminescence element, organic electroluminescence material, display device, and lighting device - Google Patents

Description

The present invention relates to a thin film, an electronic device, an organic electroluminescence element, an organic electroluminescence material, a display device, and a lighting device.

Electronic devices are widely used in general, and typical examples thereof include solar panels and organic electroluminescence elements. An organic electroluminescence device (hereinafter referred to as an organic EL device) has electrodes (anode and cathode) and a light-emitting layer. Holes injected from the anode and electrons injected from the cathode recombine within the light-emitting layer. to generate excitons. Emission of light when this exciton is deactivated is utilized.

In recent years, from the viewpoint of power saving, etc., there is a demand for improving the performance of these electronic devices. For example, an organic EL element is one example of an electronic device that is in widespread use, and various organic EL materials have been developed to improve the performance of the organic EL element. Examples thereof include organic EL materials described in Patent Document 1 and Patent Document 2. In these examples, a pyrimidine compound is used as an organic EL material to improve the performance of the organic EL device.
However, there is a demand for further improvement in the performance of electronic devices, and there is a demand for electronic devices with a lower drive voltage and an increase in drive voltage when stored for a certain period of time, that is, with improved storage stability.

WO2004/39786 U.S. Patent Application Publication No. 2007/190355

In view of the above problems, in order to improve the performance of electronic devices, the present invention provides a thin film that contributes to reducing the driving voltage of the electronic device and improving the stability during storage, an electronic device using the thin film, and an organic film using the thin film. An object of the present invention is to provide an electroluminescence element, an organic electroluminescence material used for the organic electroluminescence element, a display device, and a lighting device.

The above problems related to the present invention are solved by the following means.

1. A thin film containing a compound having a structure represented by the following general formula (1).

(In the general formula (1), Ar ₁ to Ar ₃ each independently represent a hydrogen atom, an aromatic hydrocarbon ring or a heterocyclic ring, and at least one is a pyridine ring, a pyrazine ring, a pyrimidine ring, or a quinazoline Each of Ar ₄ to Ar ₆ independently represents a hydrogen atom, an aromatic hydrocarbon ring or a heterocyclic ring, and at least one represents a pyridine ring, pyrazine ring, pyrimidine ring or quinazoline ring. n represents an integer of 3 or more and 5 or less, and each L independently represents a phenyl ring, a pyridine ring or a pyrimidine ring .)
2. 2. The thin film of claim 1, which is used adjacent to a silver thin film containing silver.

3 . 3. A thin film according to claim 1 or claim 2 , further comprising an electron injection material.

4 . An organic electroluminescent element having an electrode and a plurality of organic functional layers including a light-emitting layer,
4. An organic electroluminescence device, wherein at least one layer of the organic functional layer is the thin film according to any one of items 1 to 3 .

5 . 5. The organic electroluminescence device according to Item 4 , wherein the thin film, the electron injection layer, and the electrode are laminated in this order.

6 . The electrode is mainly composed of silver,
6. The organic electroluminescence device according to item 4 or 5 , wherein the organic functional layer is provided adjacent to the electrode.

7 . 7. The organic electroluminescence device according to any one of items 4 to 6 , wherein the electrode has a film thickness of 15 nm or less and is transparent.

8 . An organic electroluminescence material containing a compound having a structure represented by the following general formula (1).

(In the general formula (1), Ar ₁ to Ar ₃ each independently represent a hydrogen atom, an aromatic hydrocarbon ring or a heterocyclic ring, and at least one is a pyridine ring, a pyrazine ring, a pyrimidine ring, or a quinazoline Each of Ar ₄ to Ar ₆ independently represents a hydrogen atom, an aromatic hydrocarbon ring or a heterocyclic ring, and at least one represents a pyridine ring, pyrazine ring, pyrimidine ring or quinazoline ring. n represents an integer of 3 or more and 5 or less, and each L independently represents a phenyl ring, a pyridine ring or a pyrimidine ring .)

9 . A display device comprising the organic electroluminescence element according to any one of items 4 to 7 .

10 . A lighting device comprising the organic electroluminescence device according to any one of items 4 to 7 .

11 . An electronic device comprising an electrode and the thin film according to any one of items 1 to 3 .

According to the present invention, it is possible to provide an organic electroluminescence device with improved driving voltage and stability during high-temperature storage, and an organic electroluminescence material used for the organic electroluminescence device. Further, it is possible to provide a display device and a lighting device with improved drive voltage and improved stability during high-temperature storage.

Schematic diagram showing an example of a display device composed of organic EL elements Schematic diagram of display part A pixel circuit diagram Schematic diagram of a passive matrix full-color display device Schematic diagram of the lighting system Schematic diagram showing a cross section of the lighting device

The thin film of the present invention is characterized by containing a compound having a structure represented by the following general formula (1). This feature is a technical feature common to the inventions according to claims 1 to 4. Moreover, the thin film of the present invention may contain other compounds besides the compound having the structure represented by the following general formula (1).

<<Compound having a structure represented by the general formula (1)>>

In general formula (1), Ar ₁ to Ar ₃ each independently represent a hydrogen atom, an aromatic hydrocarbon ring or a heterocyclic ring, may further have a substituent, and at least one is a pyridine ring or a pyrazine ring, a pyrimidine ring, or a quinazoline ring. That is, Ar ₁ to Ar ₃ each independently represent a hydrogen atom, a substituted or unsubstituted aromatic hydrocarbon ring, or a substituted or unsubstituted heterocyclic ring, and at least one is a pyridine ring or pyrazine ring or pyrimidine ring or quinazoline ring. Specific examples of the aromatic hydrocarbon ring include, but are not limited to, benzene ring, naphthyl ring, anthracene ring, pyrene ring, and the like. Specific examples of the heterocyclic ring are not particularly limited, but some of the carbon atoms in the above aromatic hydrocarbon ring are substituted with a heteroatom (oxygen atom, nitrogen atom or sulfur atom), such as , pyridine ring, pyrrole ring, furan ring, pyran ring, imidazole ring, pyrazole ring, oxazole ring, pyridazine ring, pyrimidine ring, purine ring, triazine ring, triazole ring, quinoline ring, isoquinoline ring and the like.

In general formula (1), Ar ₄ to Ar ₆ each independently represent a hydrogen atom, an aromatic hydrocarbon ring or a heterocyclic ring, may further have a substituent, and at least one is a pyridine ring or a pyrazine ring, a pyrimidine ring, or a quinazoline ring. That is, Ar ₄ to Ar ₆ each independently represent a hydrogen atom, a substituted or unsubstituted aromatic hydrocarbon ring, or a substituted or unsubstituted heterocyclic ring, and at least one is a pyridine ring or pyrazine ring or pyrimidine ring or quinazoline ring. Specific examples of the aromatic hydrocarbon ring include, but are not limited to, benzene ring, naphthyl ring, anthracene ring, pyrene ring, and the like. Specific examples of the heterocyclic ring are not particularly limited, but some of the carbon atoms in the above aromatic hydrocarbon ring are substituted with a heteroatom (oxygen atom, nitrogen atom or sulfur atom), such as , pyridine ring, pyrrole ring, furan ring, pyran ring, imidazole ring, pyrazole ring, oxazole ring, pyridazine ring, pyrimidine ring, purine ring, triazine ring, triazole ring, quinoline ring, isoquinoline ring and the like.

In general formula (1) , n is 3 or more and 5 or less, and L each independently represents a phenyl ring, a pyridine ring , or a pyrimidine ring . These may have a substituent.

Substituents used in general formula (1) are not particularly limited, and examples thereof include alkyl groups (e.g., methyl group, ethyl group, trifluoromethyl group, isopropyl group, etc.), aryl groups (e.g., phenyl group, etc.). , a heteroaryl group (e.g., pyridyl group, carbazolyl group, etc.), a halogen atom (e.g., fluorine atom, etc.), a cyano group, or a fluorinated alkyl group, etc., and those used in the exemplary compounds described later are also preferred. .

<<Synthesis Example of Compound Having Structure Represented by General Formula (1)>>
<Synthesis Example 1>
Synthesis of compound (1) of the present invention

1.8 g (4.64 mmol) of compound (1-1), 0.84 g (2.55 mmol) of compound (1-2), 1.28 g (9.28 mmol) of potassium carbonate, and 5 mL of pure water in a 200 mL four-head Kolben , and THF 43 mL were added, and the mixture was stirred at room temperature for 30 minutes while nitrogen gas was introduced. Then, 0.575 g (0.348 mmol) of tris(dibenzylideneacetone) dipalladium (0) and 0.142 g (0.348 mmol) of 2-dicyclohexylphosphino-2',6'-dimethoxybiphenyl were added and stirred. The mixture was heated under reflux for 7 hours. After completion of the reaction, the mixture was cooled to room temperature, water was added, and the mixture was stirred and filtered. THF was added to the resulting crude crystals, and the suspension was stirred under heating under reflux, cooled to room temperature, filtered, and dried to obtain 1.56 g of solid. The resulting solid was purified by sublimation to obtain 1.04 g of compound (1) (yield 65%). The structure was confirmed by ¹ H-NMR.

<Synthesis Example 2>
Synthesis of compound (49) of the present invention

1.7 g (4.34 mmol) of compound (49-1), 0.82 g (2.48 mmol) of compound (49-2), 0.92 g (6.68 mmol) of potassium carbonate, and 4 mL of pure water in a 200 mL four-head Kolben , and 40 mL of THF were added, and the mixture was stirred at room temperature for 30 minutes while introducing nitrogen gas. Then, 0.144 g (0.25 mmol) of tris(dibenzylideneacetone) dipalladium (0) and 0.102 g (0.25 mmol) of 2-dicyclohexylphosphino-2',6'-dimethoxybiphenyl were added and stirred. It was heated to reflux for 7 hours. After completion of the reaction, the mixture was cooled to room temperature, water was added, and the mixture was stirred and filtered. THF was added to the obtained crude crystals, and the suspension was stirred under heating under reflux, then cooled to room temperature, filtered and dried to obtain 1.02 g of a solid. The resulting solid was purified by sublimation to obtain 0.90 g of compound (49) (yield 60%). The structure was confirmed by ¹ H-NMR.

<<Specific examples and reference examples of compounds having a structure represented by general formula (1)>>
Specific examples and reference examples of the compound having the structure represented by formula (1) are shown below. These compounds are examples, and the present invention is not limited to them.

The thin film of the present invention described above is not particularly limited in its usage, and can be used in various products. Examples of products using the thin film of the present invention include various electronic devices such as solar panels and organic EL devices. These electronic devices have an electrode made of metal or the like and the thin film.

Further, the organic electroluminescence material of the present invention is characterized by containing a compound having a structure represented by the general formula (1). General formula (1) is as described above.

In addition, the plurality of nitrogen-containing heterocycles in the compound having the structure represented by the general formula (1) interacts with silver, reduces the diffusion distance of silver atoms, and can suppress aggregation of silver. can. It is also possible thereby to achieve a uniform film of an electrode based on silver. Details of the electrodes will be described later. In addition, since the compound of the present invention can suppress the crystallinity, it can be easily laminated during film formation and the smoothness can be improved. Furthermore, by suppressing aggregation of silver, it is possible to suppress an increase in grain boundaries of silver atoms, so that it is possible to suppress a decrease in driving voltage and an increase in driving voltage over time.

In addition, the heteroatom in the compound having the structure represented by the general formula (1) interacts with alkali metals, alkaline earth metals, and rare earths used as electron injection materials, and the alkali metals used as electron injection materials It is possible to suppress diffusion of each atom of a metal, an alkaline earth metal, and a rare earth element into the light-emitting layer, thereby suppressing a decrease in driving voltage and an increase in driving voltage over time.

<<Constituent layer of organic EL element>>
Constituent layers of the organic EL element of the present invention will be described. In the organic EL device of the present invention, the electrodes mean an anode and a cathode. Preferable specific examples of the layer structure of various organic functional layers sandwiched between the anode and the cathode are shown below, but the present invention is not limited thereto.
(i) anode/emissive layer unit/electron transport layer/cathode (ii) anode/hole transport layer/emissive layer unit/electron transport layer/cathode (iii) anode/hole transport layer/emissive layer unit/hole blocking layer/electron-transporting layer/cathode (iv) anode/hole-transporting layer/emissive layer unit/hole-blocking layer/electron-transporting layer/cathode buffer layer/cathode (v) anode/anode buffer layer/hole-transporting layer/cathode Layer unit/hole blocking layer/electron transport layer/cathode buffer layer/cathode

Furthermore, the light-emitting layer unit may have a non-light-emitting intermediate layer between multiple light-emitting layers, and may have a multi-photon unit structure in which the intermediate layer is a charge generating layer. In this case, the charge generation layer may be made of ITO (indium tin oxide), IZO (indium zinc oxide), ZnO ₂ , TiN, ZrN, HfN, TiOx, VOx, CuI, InN, GaN, CuAlO ₂ , 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 Multilayer films such as O3/Au/Bi2O3 _{, TiO2} /TiN/ _{TiO2 , TiO2} /ZrN/ _TiO2 , fullerenes such as C60, _{oligothiophenes} , metal phthalocyanines, metal _- free phthalocyanines , metal porphyrins, metal-free porphyrins and other conductive organic compound layers. Moreover, the charge generation layer has a function of promoting electron transfer between the plurality of light emitting layers, and preferably contains an alkali metal such as lithium, an alkaline earth metal, a rare earth element, or the like. In addition, the function and configuration of the charge generation layer may be the same as those of the electron injection layer described later.
Each layer constituting the organic EL element of the present invention will be described below.

《Organic functional layer》
The organic EL device of the present invention has an anode, a plurality of organic functional layers including a light-emitting layer, and a cathode in this order. That is, the organic functional layer according to the present invention is characterized by being positioned between the anode and the cathode.
The organic EL device of the present invention has a plurality of organic functional layers, and the organic functional layers include a light-emitting layer and the thin film of the present invention described above. In addition, the number of light emitting layers may be one or plural.

Moreover, it is preferable to have a layer containing a compound having a structure represented by the general formula (1) and an electron injection material as the organic functional layer. That is, it is preferable that the thin film as the organic functional layer contains an electron injection material, or that an organic functional layer containing an electron injection material (an electron injection layer to be described later) is provided separately from the thin film.
Moreover, when an electron injection layer, which will be described later, is present, it is also preferable that the thin film, the electron injection layer, and the cathode are laminated in this order.

《Light emitting layer》
The light-emitting layer used in the present invention is a layer in which electrons and holes injected from an electrode or an electron-transporting layer and a hole-transporting layer recombine to emit light. may also 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 uniformity of the film, prevention of application of unnecessary high voltage during light emission, and improvement of the stability of the emission color with respect to the driving current, It is preferably adjusted in the range of 2 nm to 5 μm. The total layer thickness of the light-emitting layer is more preferably adjusted in the range of 2 to 200 nm, particularly preferably in the range of 5 to 100 nm.

The light-emitting layer can be formed by using a light-emitting dopant or a host compound, which will be described later, and forming a film by, for example, a vacuum deposition method, a wet method, or the like. The wet method is also called a wet process, and examples thereof include spin coating, casting, die coating, blade coating, roll coating, inkjet, printing, spray coating, curtain coating, LB (Langmuir-Blodgett (Langmuir Blodgett method)).
The light-emitting layer of the organic EL device of the present invention preferably contains a light-emitting dopant (phosphorescent dopant, fluorescent light-emitting dopant, etc.) compound and a host compound.

(1) Luminescent Dopant A luminescent dopant (also referred to as a luminescent dopant, a dopant compound, or simply a dopant) will be described.
Examples of luminescent dopants include phosphorescent dopants (also referred to as phosphorescent dopants, phosphorescent compounds, and phosphorescent compounds), fluorescent dopants (also referred to as fluorescent dopants, fluorescent compounds, and fluorescent compounds). ) can be used.

(1.1) Phosphorescent dopant A phosphorescent dopant is a compound that can be observed to emit light from excited triplet, specifically a compound that emits phosphorescence at room temperature (25° C.). A phosphorescent dopant is defined as a compound having a phosphorescent quantum yield of 0.01 or higher at 25° C., preferably 0.1 or higher.
The phosphorescence quantum yield can be measured by the method described in Experimental Chemistry Course 7, 4th Edition, Spectroscopy II, page 398 (1992 edition, Maruzen). Phosphorescence quantum yield in solution can be measured using various solvents. However, the phosphorescent dopant used in the present invention may achieve the phosphorescent quantum yield (0.01 or more) in any solvent.

There are two types of light emission principle of the phosphorescent dopant. One is an energy transfer type. In the energy transfer type, recombination of carriers occurs on the host compound to which the carriers are transported to generate an excited state of the light-emitting host compound, and this energy is transferred to the phosphorescent dopant to obtain light emission from the phosphorescent dopant. It is. The other is a carrier trap type. In the carrier trap type, the phosphorescent dopant becomes a carrier trap, recombination of carriers occurs on the phosphorescent dopant, and light emission from the phosphorescent dopant is obtained. In either case, the condition is that the excited state energy of the phosphorescent dopant is lower than the excited state energy of the host compound.

(1.2) Fluorescent dopants Fluorescent dopants include coumarin-based dyes, pyran-based dyes, cyanine-based dyes, croconium-based dyes, squarium-based dyes, oxobenzanthracene-based dyes, fluorescein-based dyes, rhodamine-based dyes, pyrylium-based dyes, Examples include perylene-based dyes, stilbene-based dyes, polythiophene-based dyes, rare-earth complex-based phosphors, and compounds with high fluorescence quantum yields typified by laser dyes.

[Combination with conventionally known dopants]
Moreover, the light-emitting dopant used in the present invention may be used in combination with a plurality of types of compounds, or may be used in combination of phosphorescent dopants having different structures, or in combination of a phosphorescent dopant and a fluorescent dopant.
Here, as the light-emitting dopant, the conventionally known compound described in International Publication No. 2013/061850 can be suitably used, but the present invention is not limited thereto.

[Host compound]
A host compound (also referred to as a light-emitting host or light-emitting host compound) that can be used in the present invention has a mass ratio of 20% or more in the layer among the compounds contained in the light-emitting layer, and is at room temperature ( 25° C.) is defined as a compound having a phosphorescence quantum yield of phosphorescence emission of less than 0.1. Preferably the phosphorescence quantum yield is less than 0.01. Moreover, it is preferable that the mass ratio in the layer is 20% or more among the compounds contained in the light-emitting layer.

The host compound that can be used in the present invention is not particularly limited, and compounds that are conventionally used in organic EL devices can be used. Representative examples are those having a basic skeleton such as carbazole derivatives, triarylamine derivatives, aromatic derivatives, nitrogen-containing heterocyclic compounds, thiophene derivatives, furan derivatives, oligoarylene compounds, etc., or carboline derivatives and diazacarbazole derivatives (here and the diazacarbazole derivative means that at least one carbon atom of the hydrocarbon ring constituting the carboline ring of the carboline derivative is substituted with a nitrogen atom.) and the like.

A known host compound that can be used in the present invention is preferably a compound that has a hole-transporting ability and an electron-transporting ability, prevents emission from becoming longer in wavelength, and has a high Tg (glass transition temperature).
Moreover, in the present invention, a conventionally known host compound may be used alone, or a plurality of types may be used in combination. By using a plurality of types of host compounds, it is possible to adjust the movement of electric charges, and to improve the efficiency of the organic EL device. In addition, by using a plurality of conventionally known compounds, it is possible to mix different luminescence, thereby obtaining an arbitrary luminescence color.

The host compound used in the present invention may be a low-molecular-weight compound, a high-molecular-weight compound having a repeating unit, or a low-molecular-weight compound (polymerizable host compound) having a polymerizable group such as a vinyl group or an epoxy group. good. One or a plurality of such compounds may be used as the host compound used in the present invention.

Specific examples of known host compounds include compounds described in the following documents.
JP 2001-257076, 2002-308855, 2001-313179, 2002-319491, 2001-357977, 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 and the like.

"cathode"
As the cathode, an electrode material having a small work function (4 eV or less) (referred to as an electron-injecting metal), an alloy, an electrically conductive compound, or a mixture thereof is also used. Specific examples of such electrode materials include aluminum, sodium, sodium-potassium alloys, magnesium, lithium, magnesium/copper mixtures, magnesium/silver mixtures, magnesium/aluminum mixtures, magnesium/indium mixtures, aluminum/aluminum oxide (Al ₂ O ₃ ) mixtures, indium, lithium/aluminum mixtures, rare earth metals, and the like. Among these, mixtures of electron-injecting metals and second metals, which are stable metals having a higher work function value, such as magnesium/silver mixtures, from the viewpoint of electron-injecting properties and durability against oxidation, Magnesium/aluminum mixtures, magnesium/indium mixtures, aluminum/aluminum oxide (Al ₂ O ₃ ) mixtures, lithium/aluminum mixtures, aluminum and the like are suitable.
The cathode is particularly preferably composed mainly of silver. Examples of alloys containing silver as a main component include silver magnesium (AgMg), silver copper (AgCu), silver palladium (AgPd), silver palladium copper (AgPdCu), and silver indium (AgIn).
In addition, the “main component” in the present invention means that it is contained in the film or layer in an amount of 50% by mass or more, preferably 80% by mass or more, and more preferably 90% by mass or more. .

A cathode using an alloy containing silver as a main component may have a structure in which a plurality of layers are laminated as necessary.
The film thickness of the cathode is usually selected in the range of 10 nm to 5 μm, preferably 50 to 200 nm. When using an alloy containing silver as a main component, the film thickness is preferably 15 nm or less, more preferably 12 nm or less. Moreover, when using an alloy containing silver as a main component, the film thickness is preferably 4 nm or more. That is, when an alloy containing silver as a main component is used, the film thickness is more preferably within the range of 4 to 12 nm. When the film thickness is within this range, the component of light absorbed or reflected by the film can be further reduced, the light transmittance can be more maintained, and the conductivity of the layer can be more ensured.

As described above, when the cathode contains silver as a main component, the cathode is preferably adjacent to the organic functional layer containing the compound having the structure represented by the general formula (1), that is, the thin film.
The thin film is preferably adjacent to the cathode, and even when the cathode is formed on the thin film, the thin film may be formed on the cathode. Furthermore, a cathode may be formed on the thin film, the thin film may be further formed on the cathode, and the cathode may be sandwiched between two layers of the thin films.

When a cathode containing silver as a main component is formed on the thin film, the silver atoms constituting the cathode interact with the compound having the structure represented by the general formula (1) contained in the thin film. do. As a result, the diffusion distance of silver atoms on the surface of the thin film is reduced, and aggregation (migration) of silver at specific sites can be suppressed.
That is, silver atoms first form two-dimensional nuclei on the surface of the thin film having atoms that have an affinity with silver atoms, and then form a two-dimensional single crystal layer around the nuclei (a layered growth type (Frank)). -van der Merwe: FM type).

In general, an island-like growth type (Volume-type) is used in which silver atoms adhering to the surface of the thin film combine while diffusing on the surface to form a three-dimensional nucleus and grow in a three-dimensional island shape. Weber: VW type) is believed to facilitate film formation in an island shape.
However, in the present invention, it is presumed that the compound having the structure represented by the general formula (1) contained in the thin film suppresses the island-like growth and promotes the layer-like growth.
Therefore, it is possible to obtain a cathode having a thin film thickness and a uniform film thickness. As a result, it is possible to obtain a transparent electrode in which electrical conductivity is ensured while maintaining light transmittance due to the thin film thickness.

Furthermore, as described above, by suppressing aggregation of silver at specific sites, it is possible to suppress the increase of grain boundaries of silver atoms at the interface between the cathode and the thin film. Therefore, it is possible to suppress a dramatic increase in drive voltage.

In addition, when the thin film is formed on the cathode, the silver atoms forming the cathode interact with the atoms contained in the thin film that have an affinity for the silver atoms, and it is thought that the motility is suppressed. be done. As a result, irregular reflection can be suppressed by improving the surface smoothness of the cathode, and the light transmittance can be improved.
We presume that such an interaction suppresses changes in the film quality of the cathode against physical stimuli such as heat and temperature, and improves durability.

The cathode can be produced by forming a thin film of an alloy containing silver as a main component or a general electrode material by a method such as vapor deposition or sputtering. In addition, from the viewpoint of lowering the drive voltage and further improving the luminous efficiency, device life, etc., the sheet resistance value as the cathode is several hundred Ω/sq. (Ω/□) or less, preferably 50Ω/sq. The following is more preferable, especially 25Ω/sq. The following are preferable. Although the lower limit is not particularly defined, for example, 1Ω/sq. It can be as above.
In order to allow the emitted light to pass therethrough, if either the anode or the cathode of the organic EL element is transparent or translucent, the luminance of the emitted light is improved, which is convenient. The light transmittance of the cathode is preferably 30% or more, more preferably 50% or more. More preferably, it is 70% or more. Although the upper limit is not particularly defined, it can be, for example, 95% or less.
In addition, a transparent or translucent cathode can be produced by forming the above-mentioned metal in a thickness of 1 to 20 nm on the cathode and then forming thereon a conductive transparent material mentioned in the explanation of the anode which will be described later. . By applying this, it is possible to fabricate a device in which both the anode and the cathode are transparent.

《Electron transport layer》
The electron transport layer is made of a material having a function of transporting electrons, and as described above, preferably contains a compound having a structure represented by the general formula (1). That is, the electron transport layer is preferably the thin film described above. 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 multiple layers. Furthermore, an electron injection transport layer may be provided which also contains the material contained in the electron injection layer described later.
The electron-transporting layer may have a function of transferring electrons injected from the cathode to the light-emitting layer, and as a constituent material of the electron-transporting layer, any one of conventionally known compounds may be selected and used together. is also possible.

Examples of conventionally known materials used for the electron transport layer (hereinafter referred to as electron transport materials) include nitro-substituted fluorene derivatives, diphenylquinone derivatives, thiopyran dioxide derivatives, polycyclic aromatic hydrocarbons such as naphthalene perylene, Heterocyclic tetracarboxylic acid anhydride, carbodiimide, frelenylidenemethane derivative, anthraquinodimethane and anthrone derivative, oxadiazole derivative, carboline derivative, or the number of carbon atoms in 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.
Furthermore, among the above oxadiazole derivatives, a thiadiazole derivative in which an oxygen atom in the oxadiazole ring is substituted with a sulfur atom, and a quinoxaline derivative having a quinoxaline ring, which is known as an electron-withdrawing group, can also be used as the electron-transporting material.
Polymeric materials in which these materials are introduced into the polymer chain or in which these materials are used as the main chain of the polymer can also be used.

Also, metal complexes of 8-quinolinol derivatives such as tris(8-quinolinol)aluminum (Alq) ₃ , 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), etc., and the central metals of these metal complexes are In and Mg , Cu, Ca, Sn, Ga or Pb can also be used as electron transport materials.
In addition, metal-free or metal phthalocyanines, or those whose terminals are substituted with alkyl groups, sulfonic acid groups, or the like can also be used as electron transport materials.
Inorganic semiconductors such as n-type Si and n-type SiC can also be used as electron transport materials.

The electron transport layer is preferably formed by thinning an electron transport material by, for example, a vacuum deposition method, a wet method, or the like. The wet method is also called a wet process, and examples thereof include spin coating, casting, die coating, blade coating, roll coating, inkjet, printing, spray coating, curtain coating, LB (Langmuir-Blodgett (Langmuir Blodgett method)).

The layer thickness of the electron-transporting layer is not particularly limited, but is usually about 5 to 5000 nm, preferably 5 to 200 nm. The electron transport layer may have a one-layer structure composed of one or more of the above materials.
Further, it may be used by doping with an n-type dopant such as a metal compound such as a metal complex or a metal halide.

As an example of a conventionally known electron-transporting material preferably used for forming the electron-transporting layer of the organic EL device of the present invention, the compounds described in International Publication No. WO 2013/061850 can be suitably used. is not limited to

<<Injection layer: electron injection layer (cathode buffer layer), hole injection layer>>
An injection layer is optionally provided, and includes an electron injection layer and a hole injection layer, and may be present between the anode and the light-emitting layer or the hole-transporting layer and between the cathode and the light-emitting layer or the electron-transporting layer. .
An injection layer is a layer provided between an electrode and an organic functional layer in order to reduce driving voltage and improve luminance. The injection layer is described in detail in "Organic EL element and its industrial front" (published by NTS on November 30, 1998), Part 2, Chapter 2, "Electrode materials" (pp. 123-166). It 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 also described in JP-A-9-45479, JP-A-9-260062 and JP-A-8-288069. Specific examples of the anode buffer layer include a phthalocyanine buffer layer typified by copper phthalocyanine, a hexaazatriphenylene derivative buffer layer as described in JP-A-2003-519432, JP-A-2006-135145, etc. Oxide buffer layers typified by vanadium oxide, amorphous carbon buffer layers, polymer buffer layers using conductive polymers such as polyaniline (emeraldine) and polythiophene, and tris(2-phenylpyridine) iridium complexes. and an ortho-metalated complex layer.

The details of the cathode buffer layer (electron injection layer) are also described in JP-A-6-325871, JP-A-9-17574 and JP-A-10-74586. Specifically, the cathode buffer layer includes a metal buffer layer typified by strontium and aluminum, an alkali metal compound buffer layer typified by lithium, lithium fluoride, sodium fluoride, and potassium fluoride, magnesium fluoride, and fluoride. Alkaline earth metal compound buffer layers typified by cesium chloride, rare earth metal compound buffer layers typified by ytterbium and scandium, oxide buffer layers typified by aluminum oxide, and the like can be used. The buffer layer (injection layer) is desirably a very thin film, and although it depends on the material, the film thickness is preferably in the range of 0.1 nm to 5 μm.

Moreover, as described above, the organic functional layer preferably contains a compound having a structure represented by the general formula (1).

For example, when the electron-transporting layer and the cathode are adjacent to each other and no electron-injecting layer is provided, the electron-transporting layer contains an electron-injecting material in addition to the compound having the structure represented by the general formula (1). is also preferred (ie an electron injection transport layer is provided). In such a case, and when silver is used as the main component of the cathode, as described above, by suppressing the aggregation of silver at the specific site, the driving voltage decreases and the driving voltage increases over time. can be suppressed.

For example, when an electron-transporting layer, an electron-injecting layer, and a cathode are laminated in this order, the electron-transporting layer contains a compound having a structure represented by the general formula (1) (the electron-transporting layer corresponds to the thin film). ), it is also preferable to contain an electron injection material in the electron injection layer. In this case, the compound having the structure represented by the general formula (1) interacts with the alkali metal, alkaline earth metal, rare earth metal, etc. used as the electron injection material, and the electron injection material diffuses into the light emitting layer. Therefore, it is considered possible to suppress the decrease in the drive voltage and the increase in the drive voltage over time.

<<Blocking Layer: Hole Blocking Layer, Electron Blocking Layer>>
The blocking layer is provided as necessary in addition to the basic constituent layers of the organic compound thin film as described above. For example, JP-A-11-204258, JP-A-11-204359, and page 237 of "Organic EL element and its industrial front (published by NTS on November 30, 1998)". There is a hole blocking (hole blocking) layer.

The hole-blocking layer has the function of an electron-transporting layer in a broad sense, and is made of a hole-blocking material that has a function of transporting electrons but has a very low ability to transport holes. The hole-blocking layer transports electrons and blocks holes, thereby improving the recombination probability of electrons and holes.
Moreover, the structure of the electron transport layer mentioned above can be used as a hole blocking layer as needed.
The hole-blocking layer of the organic EL device of the present invention is preferably provided adjacent to the light-emitting layer.
In the hole-blocking layer, the carbazole derivative, carboline derivative, and diazacarbazole derivative (here, the diazacarbazole derivative means that any one of the carbon atoms constituting the carboline ring is a nitrogen atom). is replaced with.) is preferably contained.

On the other hand, the electron-blocking layer has the function of a hole-transporting layer in a broad sense, and is made of a material that has a function of transporting holes but has a remarkably low ability to transport electrons. The electron blocking layer can improve the recombination probability of electrons and holes by blocking electrons while transporting holes.
Moreover, the structure of the hole transport layer described later can be used as an electron blocking layer as needed. The layer thickness of the hole-blocking layer and the electron-transporting layer according to the invention is preferably 3 to 100 nm, more preferably 5 to 30 nm.

<<Hole transport layer>>
The hole-transporting layer is made of a hole-transporting material having a function of transporting holes, and in a broad sense includes a hole-injecting layer and an electron-blocking layer. The hole transport layer can be provided as a single layer or multiple layers.
The hole transport material has either hole injection or transport or electron blocking 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 include stilbene derivatives, silazane derivatives, aniline copolymers, conductive polymer oligomers, especially thiophene oligomers.
Azatriphenylene derivatives as described in JP-A-2003-519432, JP-A-2006-135145, etc. can also be used as the hole transport material.

Although the above materials can be used as the hole transport material, it is preferable to use porphyrin compounds, aromatic tertiary amine compounds and styrylamine compounds, particularly aromatic tertiary amine compounds.
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'-diaminodiphenylether;4,4'-bis(diphenylamino) quadri Phenyl; N,N,N-tri(p-tolyl)amine; 4-(di-p-tolylamino)-4'-[4-(di-p-tolylamino)styryl]stilbene; 4-N,N-diphenyl amino-(2-diphenylvinyl)benzene; 3-methoxy-4'-N,N-diphenylaminostilbene; N-phenylcarbazole, as well as two fused aromatics described in US Pat. No. 5,061,569. Those having a ring in the molecule, for example, 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (NPD), triphenylamine described in JP-A-4-308688 Examples include 4,4',4''-tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine (MTDATA) in which three units are linked in a starburst configuration.

Furthermore, polymer materials in which these materials are introduced into the polymer chain or these materials are used as the main chain of the polymer can also be used.
Inorganic compounds such as p-type-Si and p-type-SiC can also be used as hole-injecting materials and hole-transporting materials.

Also, Japanese Patent Application Laid-Open No. 11-251067, J. Am. Huang et. al. A so-called p-type hole transport material, as described in Applied Physics Letters 80 (2002), p.139, can also be used. In the present invention, it is preferable to use these materials because a light-emitting device with higher efficiency can be obtained.

The hole-transporting layer can be formed by thinning the hole-transporting material by a known method such as a vacuum vapor deposition method, a spin coating method, a casting method, a printing method including an inkjet method, or an LB method. can.
The layer thickness of the hole transport layer is not particularly limited, but is usually about 5 nm to 5 μm, preferably 5 to 200 nm. The hole transport layer may have a one-layer structure composed of one or more of the above materials.

Alternatively, a hole transport layer doped with an impurity and having a high p property may be used. Examples thereof include JP-A-4-297076, JP-A-2000-196140, and JP-A-2001-102175; Appl. Phys. , 95, 5773 (2004).
In the present invention, it is preferable to use such a hole-transporting layer with high p-property, because it is possible to produce an element with lower power consumption.

"anode"
As the anode in the organic EL element, an electrode material having a large work function (4 eV or more), a metal, an alloy, an electrically conductive compound, or a mixture thereof is preferably used. Specific examples of such electrode materials include metals such as Au, and conductive transparent materials such as CuI, ITO, SnO ₂ and ZnO.
A material such as IDIXO (In ₂ O ₃ —ZnO) that is amorphous and capable of forming a transparent conductive film may also be used. The anode may be formed by forming a thin film of these electrode substances by a method such as vapor deposition or sputtering, and forming a pattern of a desired shape by photolithography. Alternatively, if the pattern accuracy is not so required (approximately 100 μm or more), the pattern may be formed through a mask having a desired shape during vapor deposition or sputtering of the electrode material.

Alternatively, when a coatable substance such as a conductive organic compound is used, a wet film formation method such as a printing method or a coating method can be used. When light is extracted from this anode, it is desirable that the light transmittance is greater than 10%, and the sheet resistance value of the anode is several hundred Ω/sq. The following are preferred. Furthermore, although the film thickness depends on the material, it is usually selected in the range of 10 to 1000 nm, preferably 10 to 200 nm.

《Support substrate》
Supporting substrates (hereinafter also referred to as bases, substrates, substrates, supports, etc.) that can be used in the organic EL element of the present invention are not particularly limited in type, such as glass and plastic, and can be transparent. It can be transparent or opaque. When light is extracted from the support substrate side, the support substrate is preferably transparent. Glass, quartz, and a transparent resin film can be mentioned as a transparent support substrate that is preferably used. A particularly preferable support substrate is a resin film capable of imparting flexibility to the organic EL element.

Examples of resin films include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyethylene, polypropylene, cellophane, cellulose diacetate, cellulose triacetate (TAC), cellulose acetate butyrate, cellulose acetate propionate ( CAP), cellulose esters such as 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, polysulfones, polyetherimide, polyetherketoneimide, polyamide, fluororesin, nylon, polymethyl methacrylate, acrylic or polyarylates, Arton (trade name manufactured by JSR) or APEL (trade name, manufactured by Mitsui Chemicals, Inc.).

An inorganic coating, an organic coating, or a hybrid coating of both may be formed on the surface of the resin film. The hybrid coating has a water vapor permeability (25 ± 0.5°C, relative humidity (90 ± 2)%) measured by a method in accordance with JIS K ^7129-1992 . A barrier film is preferred. Furthermore, the hybrid coating has an oxygen permeability of 1×10 ⁻³ mL/m ² ·24 h·atm or less and a water vapor permeability of 1×10 ⁻⁵ as measured by a method based on JIS K 7126-1987. It is preferably a high gas barrier film of g/m ² ·24h or less.

As the material for forming the gas barrier layer, any material can be used as long as it has a function of suppressing the infiltration of substances that cause deterioration of the device, such as moisture and oxygen. For example, silicon oxide, silicon dioxide, silicon nitride, etc. can be used. . Furthermore, in order to improve the fragility of the film, it is more preferable to have a laminated structure of these inorganic layers and layers made of organic materials. The order of lamination of the inorganic layer and the organic functional layer is not particularly limited, but it is preferable to alternately laminate the two multiple times.

The method for forming the gas barrier layer is not particularly limited. A method, a plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, or the like can be used. However, the atmospheric pressure plasma polymerization method as described in JP-A-2004-68143 is particularly preferable.
Examples of opaque support substrates include metal plates such as aluminum and stainless steel, films, opaque resin substrates, ceramic substrates, and the like.

The external extraction yield at room temperature of light emitted from the organic EL device of the present invention is preferably 1% or more, more preferably 5% or more.
Here, external extraction quantum yield (%)=number of photons emitted outside the organic EL element/number of electrons passed through the organic EL element×100.
Further, a hue improving filter such as a color filter may be used in combination, or a color conversion filter for converting the emission color from the organic EL element into multiple colors using a phosphor may be used in combination. When using a color conversion filter, the λmax of light emitted from 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 element, a method for producing an element 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 explained.
First, a thin film of a desired electrode material, for example, an anode material is formed on a suitable substrate to a thickness of 1 μm or less, preferably 10 to 200 nm, to prepare 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, a cathode buffer layer, etc., which is an element material, is formed thereon.

As a method for forming a thin film, for example, a film can be formed by a vacuum evaporation 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. However, as the wet method, a die coating method, a roll coating method, an inkjet method, a spray coating method, and the like, which are highly suitable for a roll-to-roll system, are preferable from the viewpoint of high productivity and the ability to form a precise thin film. . Also, a different film formation method may be applied for each layer.

Examples of the liquid medium for dissolving or dispersing the organic EL material such as the light-emitting dopant used in the present invention include ketones such as methyl ethyl ketone and cyclohexanone, fatty acid esters such as ethyl acetate, halogenated hydrocarbons such as dichlorobenzene, Aromatic hydrocarbons such as toluene, xylene, mesitylene and cyclohexylbenzene, aliphatic hydrocarbons such as cyclohexane, decalin and dodecane, and organic solvents such as dimethylformamide (DMF) and DMSO can be used.
Moreover, as a dispersion method, it can be dispersed by a dispersion method such as ultrasonic wave, high shear force dispersion, media dispersion, or the like.

After these layers are formed, a thin film made of a cathode material is formed thereon to a thickness of 1 μm or less, preferably in the range of 50 to 200 nm, and a cathode is provided to obtain a desired organic EL element. .
Alternatively, the order can be reversed to produce the cathode, the cathode buffer layer, the electron transport layer, the hole blocking layer, the light emitting layer, the hole transport layer, the hole injection layer, and the anode in this order.
It is preferable that the organic EL device of the present invention is produced from the hole injection layer to the cathode by one evacuation, but the device may be taken out in the middle and subjected to a different film formation method. At that time, it is preferable to carry out the work in a dry inert gas atmosphere.

《Seal》
As a sealing means used in the present invention, for example, a method of adhering a sealing member, an electrode, and a supporting substrate with an adhesive can be mentioned.
The sealing member may be arranged so as to cover the display area of the organic EL element, and may be in the form of a concave plate or a flat plate. Moreover, transparency and electrical insulation are not critical.

Specifically, glass plates, polymer plates/films, metal plates/films, and the like can be mentioned. Examples of glass plates include soda-lime glass, barium-strontium-containing glass, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass, and quartz.
Further, as the polymer plate, those made of polycarbonate, acryl, polyethylene terephthalate, polyether sulfide, polysulfone, etc. can be mentioned.
The metal plate includes 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 or a metal film can be preferably used because the device can be made thinner.
Furthermore, the polymer film has an oxygen permeability of 1×10 ⁻³ mL/m ² ·24h·atm or less measured by a method in accordance with JIS K 7126-1987, and measured by a method in accordance with JIS K 7129-1992. It is preferable that the water vapor transmission rate (25±0.5° C., relative humidity (90±2)%) is 1×10 ⁻³ g/m ² ·24 h or less.
Sandblasting, chemical etching, or the like is used to process the sealing member into a concave shape.

Specific examples of adhesives include photocurable and thermosetting adhesives having reactive vinyl groups of acrylic acid-based oligomers and methacrylic acid-based oligomers, and moisture-curable adhesives such as 2-cyanoacrylic acid esters. be able to. Thermal and chemical curing types (two-liquid mixture) such as epoxy systems can also be mentioned. Hot-melt type polyamides, polyesters and polyolefins can also be mentioned. Further, a cationic curing type ultraviolet curing type epoxy resin adhesive can be mentioned.

Since the organic EL element may be deteriorated by heat treatment, it is preferable to use a material that can be adhesively cured from room temperature to 80°C. Also, a desiccant may be dispersed in the adhesive. A commercially available dispenser may be used to apply the adhesive to the sealing portion, or printing such as screen printing may be used.

It is also preferable to coat the electrode and the organic functional layer on the outside of the electrode on the side facing the support substrate with the organic functional layer sandwiched therebetween, and form a layer of an inorganic substance or an organic substance in contact with the support substrate to form a sealing film. can be done. In this case, the material for forming the film may be any material that has a function of suppressing the infiltration of substances that cause deterioration of the device, such as moisture and oxygen. For example, silicon oxide, silicon dioxide, silicon nitride, and the like can be used. can.
Furthermore, in order to improve the fragility of the film, it is preferable to have a laminated structure of these inorganic layers and layers made of organic material. Methods for forming these films are not particularly limited, and examples include vacuum deposition, sputtering, reactive sputtering, molecular beam epitaxy, cluster ion beam, ion plating, plasma polymerization, and atmospheric pressure plasma. A polymerization method, a plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, or the like can be used.

An inert gas such as nitrogen or argon or an inert liquid such as fluorocarbon or silicone oil can be injected into the gap between the sealing member and the display area of the organic EL element in the gas phase and the liquid phase. preferable. A vacuum is also possible. Also, a hygroscopic compound can be sealed inside.
Examples of hygroscopic compounds include metal oxides (e.g. sodium oxide, potassium oxide, calcium oxide, barium oxide, magnesium oxide, aluminum oxide, etc.), sulfates (e.g. sodium sulfate, calcium sulfate, magnesium sulfate, cobalt sulfate etc.), metal halides (e.g., calcium chloride, magnesium chloride, cesium fluoride, tantalum fluoride, cerium bromide, magnesium bromide, barium iodide, magnesium iodide, etc.), perchlorates (e.g., perchloric acid barium, magnesium perchlorate, etc.), and anhydrous salts are preferably used for sulfates, metal halides and perchlorates.

<Protective film, protective plate>
A protective film or a protective plate may be provided on the outside of the sealing film or the sealing film on the side facing the support substrate with the organic functional layer interposed therebetween in order to increase the mechanical strength of the element. In particular, when the sealing is performed by the sealing film, the mechanical strength is not necessarily high, so it is preferable to provide such a protective film and protective plate. As a material that can be used for this, the same glass plate, polymer plate/film, metal plate/film, etc. used for sealing can be used. is preferably used.

《Light Extraction》
An organic EL element emits light inside a layer with a higher refractive index than air (refractive index is about 1.7 to 2.1), and only about 15 to 20% of the light generated in the light emitting layer can be extracted. is commonly said. This is because the light incident on the interface (the interface between the transparent substrate and the air) at an angle θ greater than the critical angle is totally reflected and cannot be taken out of the device. Another reason is that the light is totally reflected between the transparent electrode or the light-emitting layer and the transparent substrate, the light is guided through the transparent electrode or the light-emitting layer, and as a result, the light escapes in the lateral direction of the device.

Methods for improving the efficiency of light extraction include, for example, a method of forming unevenness on the surface of a transparent substrate to prevent total reflection at the interface between the transparent substrate and the air (U.S. Pat. No. 4,774,435); A method of improving efficiency by imparting a property (JP-A-63-314795), a method of forming a reflective surface on the side surface of the element (JP-A-1-220394), 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. 172691/1987), and introducing a flat layer having a lower refractive index than the substrate between the substrate and the light emitter. method (Japanese Unexamined Patent Publication No. 2001-202827), a method of forming a diffraction grating between any of the substrate, the transparent electrode layer, and the light-emitting layer (including between the substrate and the outside world) (Japanese Unexamined Patent Publication No. 11-283751), etc. There is

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 that of the substrate between the substrate and the light emitter, or a method of introducing a diffraction grating between any of the substrate, the transparent electrode layer, and the light emitting layer (including between the substrate and the outside world). can be suitably used.
By combining these means, the present invention can obtain an element with even higher luminance or excellent durability.

When a medium with a low refractive index is formed with a thickness longer than the wavelength of light between the transparent electrode and the transparent substrate, the efficiency of extracting the light emitted from the transparent electrode to the outside increases as the refractive index of the medium becomes lower. .
Examples of the low refractive index layer include airgel, porous silica, magnesium fluoride, fluorine-based polymer, and the like. Since the refractive index of the transparent substrate is generally about 1.5 to 1.7, the low refractive index layer preferably has a refractive index of about 1.5 or less. Moreover, it is preferable that it is 1.35 or less.
Also, it is desirable that the thickness of the low refractive index medium is at least twice the wavelength in the medium. This is because when the thickness of the low-refractive-index medium is about the wavelength of light and the film thickness is such that the electromagnetic wave seeped out by evanescence penetrates into the substrate, the effect of the low-refractive-index layer is weakened.

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 the light extraction efficiency. This method utilizes the property that a 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 and second-order diffraction. In this method, a diffraction grating is introduced between any of the layers or in the medium (inside the transparent substrate or in the transparent electrode) for the light generated from the light-emitting layer that cannot escape due to total reflection between layers. By doing so, it diffracts the light and tries to extract it to the outside.

The diffraction grating to be introduced preferably has a two-dimensional periodic refractive index. This is because the light emitted from the light-emitting layer is generated randomly in all directions, so a general one-dimensional diffraction grating that has a periodic refractive index distribution only in one direction diffracts only light traveling in a specific direction. Therefore, the light extraction efficiency does not increase so much.
However, by making the refractive index distribution a two-dimensional distribution, light traveling in all directions is diffracted and the light extraction efficiency is increased.

As described above, the diffraction grating may be introduced between any layers or in the medium (inside the transparent substrate or in the transparent electrode), but it is preferably near the organic light-emitting layer where light is generated.
At this time, the period of the diffraction grating is preferably about 1/2 to 3 times the wavelength of light in the medium.
The arrangement of the diffraction gratings is preferably two-dimensionally repeated, such as a square lattice, a triangular lattice, or a honeycomb lattice.

《Condensing sheet》
The organic EL element of the present invention can be processed to provide a microlens array structure on the light extraction side of the substrate, or combined with a so-called light-condensing sheet, so that it can be directed in a specific direction, such as the light emitting surface Condensing light in the front direction can increase the luminance in a specific direction.
As an example of the microlens array, square pyramids each having a side of 30 μm and an apex angle of 90 degrees are arranged two-dimensionally on the light extraction side of the substrate. One side is preferably 10 to 100 μm. If it is smaller than this, the effect of diffraction will occur and coloring will occur.

As the light-condensing sheet, for example, it is possible to use one that has been put to practical use in LED backlights of liquid crystal display devices. As such a sheet, for example, a brightness enhancement film (BEF) manufactured by Sumitomo 3M Co., Ltd. can be used.
The shape of the prism sheet may be, for example, a triangular stripe with an apex angle of 90 degrees and a pitch of 50 μm formed on the base material, or a shape with rounded apex angles and a randomly varying pitch. It may be a curved shape or other shape.
Moreover, in order to control the light radiation angle from the light emitting element, a light diffusing plate/film may be used together with the light collecting sheet. For example, a diffusion film (light up) manufactured by Kimoto Co., Ltd. can be used.

《Application》
The organic EL device of the present invention can be used for display devices, displays, various light-emitting devices, and the like. Examples of light-emitting devices include lighting devices (home lighting, vehicle interior lighting), backlights for clocks and liquid crystals, billboard advertisements, traffic lights, light sources for optical storage media, light sources for electrophotographic copiers, light sources for optical communication processors, and light sources. Examples include, but are not limited to, the light source of the sensor. In particular, it can be effectively used as a backlight for a liquid crystal display device and a light source for illumination.

In the organic EL element of the present invention, patterning may be performed by a metal mask, an inkjet printing method, or the like during film formation, if necessary. When patterning, only the electrodes may be patterned, or the electrodes and the light-emitting layer may be patterned. All layers of the element may be patterned, and a conventionally known method can be used to fabricate the element.

The color emitted by the organic EL element of the present invention and the compound according to the present invention is shown in FIG. The color is determined by applying the results of measurement with a total CS-1000 (manufactured by Konica Minolta, Inc.) to the CIE chromaticity coordinates.
In addition, when the organic EL device of the present invention is a white device, white means that the chromaticity in the CIE 1931 color system at 1000 cd/m ² is X when the 2 degree viewing angle front luminance is measured by the above method. =0.33±0.07 and Y=0.33±0.1.

《Display device》
The organic EL device of the present invention can also be used in display devices.
A display device of the present invention comprises the organic EL element of the present invention. Although the display may be monochromatic or multicolor, a multicolor display will be described here.
In the case of a multicolor display device, a shadow mask is provided only when forming a light-emitting layer, and a film can be formed on one surface by vapor deposition, casting, spin coating, inkjet, printing, or the like.
When only the light-emitting layer is patterned, the method is not particularly limited, but vapor deposition, inkjet, spin coating, and printing are preferred.

The configuration of the organic EL element provided in the display device is selected from the above configuration examples of the organic EL element as required.
Moreover, the manufacturing method of the organic EL element is as shown in the aspect of manufacturing the organic EL element of the present invention.
When a DC voltage is applied to the thus obtained multicolor display device, light emission can be observed by applying a voltage of about 2 to 40 V with positive polarity to the anode and negative polarity to the cathode. Also, even if a voltage is applied with the opposite polarity, no current flows and no light is emitted. Furthermore, when an AC voltage is applied, light is emitted only when the anode is in the + state and the cathode is in the - state. Note that the AC waveform to be applied may be arbitrary.

A multicolor display device can be used as a display device, a display, and various light emission sources. In display devices and displays, full-color display is possible by using three kinds of organic EL elements emitting blue, red, and green light.
Examples of 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 or moving images. When used as a display device for reproducing moving images, the driving method may be either a passive matrix method or an active matrix method.
Light sources include home lighting, vehicle interior lighting, backlights for clocks and liquid crystal displays, billboard advertisements, traffic lights, light sources for optical storage media, light sources for electrophotographic copiers, light sources for optical communication processors, and light sources for optical sensors. However, the present invention is not limited to these.

An example of a display device having the organic EL element of the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic diagram showing an example of a display device composed of organic EL elements. 1 is a schematic diagram of a display of, for example, a mobile phone that displays image information by light emission of an organic EL element; FIG.

The display 1 has a display section A having a plurality of pixels, a control section B for performing image scanning of the display section A based on image information, a wiring section C for electrically connecting the display section A and the control section B, and the like.
The control section B is electrically connected to the display section A through the wiring section C, and sends scanning signals and image data signals to each of the plurality of pixels based on image information from the outside. Then, the pixels of each scanning line sequentially emit light according to the image data signal by the scanning signal to perform image scanning and display the image information on the display section A. FIG.

FIG. 2 is a schematic diagram of a display device using an active matrix system, and is a schematic diagram of a display section A. As shown in FIG.
The display portion A has a wiring portion C including a plurality of scanning lines 5 and data lines 6, a plurality of pixels 3, and the like on a substrate. Main members of the display portion A will be described below.
FIG. 2 shows the case where the light emitted from the pixel 3 (light emission L) is taken out in the direction of the white arrow (downward).

The scanning lines 5 and the plurality of data lines 6 of 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 connected to the pixels 3 at the orthogonal positions (details are not shown). not).
When a scanning signal is applied from the scanning line 5, the pixel 3 receives an image data signal from the data line 6 and emits light according to the received image data.
A full-color display can be realized by appropriately arranging pixels emitting red light, pixels emitting green light, and pixels emitting blue light on the same substrate.

Next, the light emitting process of the pixel will be described. FIG. 3 is a schematic diagram showing the circuit of a pixel.
A pixel includes an organic EL element 10, a switching transistor 11, a driving transistor 12, a capacitor 13, and the like. By using organic EL elements emitting red, green, and blue light as the organic EL elements 10 in a plurality of pixels and arranging these on the same substrate, full-color display can be performed.

In FIG. 3, an image data signal is applied to the drain of the switching transistor 11 from the control section B through the data line 6 . Then, when a scanning signal is applied to the gate of the switching transistor 11 from the control section B through the scanning line 5, the driving of the switching transistor 11 is turned on. The image data signal applied to the drain is transmitted to the capacitor 13 and the gate of the driving transistor 12 .

Due to the transmission of 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 driving 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. A voltage is applied from the power supply line 7 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 shifts to the next scanning line 5 by the sequential scanning of the control section B, the driving of the switching transistor 11 is turned off. However, even when the switching transistor 11 is turned off, the capacitor 13 retains the charged potential of the image data signal, so the drive transistor 12 is kept on. The organic EL element 10 continues to emit light until the next scanning signal is applied. When a scanning signal is applied next by sequential scanning, the drive 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 obtained by providing the switching transistor 11 and the driving transistor 12, which are active elements, for the organic EL element 10 of each of the plurality of pixels 3. It is carried out. Such a light emission 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 based on a multi-valued image data signal having a plurality of gradation potentials, or may be a predetermined amount of light emission on or off based on 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.
The present invention is not limited to the active matrix method described above, and may be a passive matrix method of light emission driving in which the organic EL elements emit light according to the data signal only when the scanning signal is scanned.

FIG. 4 is a schematic diagram 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 grid pattern facing each other with pixels 3 interposed therebetween.
When a scanning signal is applied to the scanning line 5 by sequential scanning, the pixels 3 connected to the applied scanning line 5 emit light according to the image data signal.
In the passive matrix method, the pixel 3 does not have an active element, and the manufacturing cost can be reduced.
A display device with improved luminous efficiency was obtained by using the organic EL element of the present invention.

《Lighting device》
The organic EL device of the present invention can also be used in lighting devices.
A lighting device of the present invention comprises the organic EL element of the present invention.
The organic EL element of the present invention may be used as an organic EL element having a resonator structure. The organic EL element having such a resonator structure may be used as a light source for optical storage media, a light source for electrophotographic copiers, a light source for optical communication processors, a light source for optical sensors, and the like. Not limited. In addition, it may be used for the above applications by causing laser oscillation.
Further, the organic EL device of the present invention may be used as a kind of lamp such as a light source for illumination or exposure, a projection device for projecting an image, or a type for directly viewing a still image or a moving image. It may be used as a display device (display).
When used as a display device for reproducing moving images, the driving method may be either a passive matrix method or an active matrix method. Alternatively, a full-color display device can be produced by using two or more kinds of the organic EL elements of the present invention having different emission colors.

For example, when a plurality of light-emitting materials are used, white light emission can be obtained by emitting light of a plurality of colors at the same time and mixing the colors. Combinations of a plurality of luminescent colors may include three emission maximum wavelengths of the three primary colors of red, green, and blue, or two luminescent colors, such as blue and yellow, and blue-green and orange, which utilize complementary colors. It may contain the maximum wavelength.

In the method of forming the organic EL device of the present invention, a mask may be provided only when forming the light-emitting layer, the hole transport layer, the electron transport layer, or the like, and the layers may be simply arranged, for example, separately by using the mask. Since other layers are common, patterning such as a mask is unnecessary, and an electrode film can be formed on one surface by vapor deposition, casting, spin coating, ink jet, printing, etc., and productivity is improved.
According to this method, unlike a white organic EL device in which light emitting elements of a plurality of colors are arranged side by side in an array, the element itself emits white light.

[One Mode of Lighting Device]
The non-light-emitting surface of the organic EL element of the present invention is covered with a glass case, and a glass substrate having a thickness of 300 μm is used as a sealing substrate. An epoxy-based photocurable adhesive (Luxtrack LC0629B manufactured by Toagosei Co., Ltd.) is applied as a sealing material around the periphery, and this is placed on the cathode and adhered to the transparent support substrate. Then, UV light is irradiated from the glass substrate side, cured, and sealed to form a lighting device as shown in FIGS.
FIG. 5 shows a schematic diagram of an illumination device, in which the organic EL element of the present invention (organic EL element 101 in the illumination device) is covered with a glass cover 102 (the sealing operation with the glass cover is The measurement was performed in a glove box under a nitrogen atmosphere (in an atmosphere of high-purity nitrogen gas with a purity of 99.999% or more) without exposing the organic EL element 101 in the apparatus to the atmosphere.
FIG. 6 shows a cross-sectional view of the lighting device, in which 105 denotes a cathode, 106 denotes an organic functional layer, and 107 denotes a glass substrate with a transparent electrode. The inside of the glass cover 102 is filled with nitrogen gas 108 and a water capturing agent 109 is provided.
A lighting device with improved luminous efficiency was obtained by using the organic EL element of the present invention.

EXAMPLES The present invention will be described in detail below with reference to Examples, but the present invention is not limited to these. In the examples, "parts" or "%" are used, but "mass parts" or "mass%" are indicated unless otherwise specified.

Although an organic EL element is used as an example in this embodiment, the thin film of the present invention is not limited to this, and can be used for various electronic devices other than the organic EL element.

[Example 1]
(Production of organic EL element)
<Production of organic EL device 1-1>
A 150 nm-thick film of ITO (indium tin oxide) was formed as an anode on a glass substrate of 50 mm×50 mm and 0.7 mm thick. After patterning, the transparent substrate with the ITO transparent electrode was ultrasonically cleaned with isopropyl alcohol. Then, it was dried with dry nitrogen gas and UV ozone cleaning was performed for 5 minutes. After that, this transparent substrate was fixed to a substrate holder of a commercially available vacuum vapor deposition apparatus.

Each crucible for vapor deposition in the vacuum vapor deposition apparatus was filled with the constituent material of each layer in the optimum amount for device fabrication. A vapor deposition crucible was made of molybdenum or tungsten resistance heating material.
After reducing the pressure to a degree of vacuum of 1×10 ⁻⁴ Pa, the vapor deposition crucible containing HAT-CN (1,4,5,8,9,12-hexaazatriphenylene hexacarbonitrile) was heated by energization. Then, it was vapor-deposited on the ITO transparent electrode at a vapor deposition rate of 0.1 nm/sec to form a hole injection layer with a layer thickness of 10 nm.

Then, α-NPD (4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl) was deposited on the hole injection layer at a deposition rate of 0.1 nm/sec to obtain a layer thickness of 40 nm. of the hole transport layer was formed. CBP (4,4′-Bis(carbazol-9-yl)biphenyl) as a host compound and Ir(ppy) ₃ (Tris(2-phenylpyridinato)iridium(III)) as a light-emitting dopant were added at 90% and 10%, respectively. A light-emitting layer having a layer thickness of 30 nm was formed by co-depositing at a deposition rate of 0.1 nm/sec so as to be vol %.

After that, comparative compound 1 (electron transport layer (1)) and LiQ (8-hydroxyquinolinato lithium) (electron transport layer (2)) were deposited at 50% and 50% by volume, respectively, at a deposition rate of 0.1 nm/sec. was co-evaporated to form an electron transport layer having a layer thickness of 30 nm. In addition, the electron transport layer (the combined layer of the electron transport layer (1) and the electron transport layer (2)) corresponds to the thin film in the present invention.
Further, LiQ was vapor-deposited at a vapor deposition rate of 0.1 nm/sec to form an electron injection layer with a film thickness of 2 nm, and then aluminum was vapor-deposited at a vapor deposition rate of 0.1 nm/sec to form a cathode with a layer thickness of 100 nm.
The non-light-emitting surface side of the device was covered with a can-shaped glass case in an atmosphere of high-purity nitrogen gas with a purity of 99.999% or more, and an electrode extraction wiring was installed to prepare an organic EL device 1-1.

<Production of organic EL elements 1-2 to 1-35>
Organic EL devices 1-2 to 1-1 were prepared in the same manner as organic EL device 1-1, except that the compounds contained in the electron transport layers (1) and (2) and the electron injection layer were changed as shown in Table I. 35 was made.
In addition, in Table I, "-" indicates that the component is not contained.

(evaluation)
(1) Measurement of Relative Driving Voltage For each organic EL element produced, the front luminance was measured on both the transparent electrode side (that is, transparent substrate side) and the counter electrode side (that is, cathode side) of each organic EL element. , and the voltage at which the sum was 1000 cd/m ² was measured as the drive voltage (V). A spectral radiance meter CS-1000 (manufactured by Konica Minolta) was used to measure luminance.
The drive voltage obtained above was applied to the following formula to obtain the relative drive voltage of each organic EL element with respect to the drive voltage of the organic EL element 1-1.
Relative driving voltage (%)=(driving voltage of each organic EL element/driving voltage of organic EL element 1-1)×100
A smaller value indicates a more favorable result.

(2) Measurement of relative drive voltage change under high-temperature storage The organic EL element produced above is caused to emit light at a temperature of 80° C. under a constant current condition of 2.5 mA/cm ² , and the drive voltage immediately after the start of light emission, The drive voltage was measured 100 hours after the start.
The obtained drive voltages before and after high-temperature storage were compared to determine the amount of change in drive voltage (the value obtained by subtracting the drive voltage after high-temperature storage from the drive voltage before high-temperature storage).
The amount of change in the drive voltage obtained above is applied to the following formula, and the relative value of the amount of change in the drive voltage of each organic EL element with respect to the amount of change in the drive voltage of the organic EL element 1-1 is calculated as relative driving under high temperature storage. It was obtained as a voltage change.
Relative drive voltage change rate (%) under high temperature storage=(drive voltage change amount of each organic EL element/drive voltage change amount of organic EL element 1-1)×100
A smaller value indicates a more favorable result.

[Example 2]
(Production of organic EL element)
<Production of organic EL device 2-1>
A 150 nm thick film of ITO (indium tin oxide) was formed as an anode on a glass substrate of 50 mm x 50 mm and a thickness of 0.7 mm. After patterning, the ITO transparent electrode was attached to the transparent substrate. was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and UV-ozone cleaned for 5 minutes.

Each crucible for vapor deposition in the vacuum vapor deposition apparatus was filled with the constituent material of each layer in the optimum amount for device fabrication. A vapor deposition crucible was made of molybdenum or tungsten resistance heating material.
After reducing the pressure to a degree of vacuum of 1×10 ⁻⁴ Pa, a crucible for vapor deposition containing HAT-CN (1,4,5,8,9,12-hexaazatriphenylene hexacarbonitrile) is energized to heat and vapor deposition. It was vapor-deposited on the ITO transparent electrode at a rate of 0.1 nm/sec to form a hole injection layer with a layer thickness of 10 nm.

Then, α-NPD (4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl) was deposited on the hole injection layer at a deposition rate of 0.1 nm/sec to obtain a layer thickness of 40 nm. of the hole transport layer was formed.
CBP as a host compound and Ir(ppy) ₃ as a light-emitting dopant were co-deposited at a deposition rate of 0.1 nm/sec so as to have volume percentages of 90% and 10%, respectively, to form a light-emitting layer having a layer thickness of 30 nm.

Thereafter, comparative compound 2 and KF were co-deposited at a deposition rate of 0.1 nm/sec so as to have a volume % of 85% and 15%, respectively, to form an electron transport layer having a layer thickness of 30 nm. Note that the electron transport layer corresponds to the thin film in the present invention.
After that, silver and magnesium were co-deposited at a deposition rate of 0.1 nm/sec so that the volume percentages of silver and magnesium were 90% and 10%, respectively, to form a cathode with a film thickness of 15 nm.
The non-light-emitting surface side of the device was covered with a can-shaped glass case in an atmosphere of high-purity nitrogen gas with a purity of 99.999% or more, and an electrode extraction wiring was installed to prepare an organic EL device 2-1.

<Production of organic EL elements 2-2 to 2-18>
Organic EL devices 2-2 to 2-18 were produced in the same manner as organic EL device 2-1, except that the electron-transporting layer compound and the cathode silver and magnesium component ratios were changed as shown in Table II. .
In addition, in the organic EL devices 2-1 to 2-18, the electron transport layer contains 15% KF, but the notation of KF is omitted in Table II.

(evaluation)
(1) Measurement of Relative Driving Voltage For each organic EL element produced, the front luminance was measured on both the transparent electrode side (that is, transparent substrate side) and the counter electrode side (that is, cathode side) of each organic EL element. , and the voltage at which the sum was 1000 cd/m ² was measured as the driving voltage (V). A spectral radiance meter CS-1000 (manufactured by Konica Minolta) was used to measure luminance.
The driving voltages obtained above were applied to the following formula to obtain the relative driving voltage of each organic EL element with respect to the driving voltage of the organic EL element 2-1.
Relative driving voltage (%)=(driving voltage of each organic EL element/driving voltage of organic EL element 2-1)×100
A smaller value indicates a more favorable result.

(2) Measurement of relative drive voltage change under high-temperature storage The organic EL element produced above is caused to emit light at a temperature of 80° C. under a constant current condition of 2.5 mA/cm ² , and the drive voltage immediately after the start of light emission, The drive voltage was measured 100 hours after the start.
The obtained drive voltages before and after high-temperature storage were compared to determine the amount of change in drive voltage (the value obtained by subtracting the drive voltage after high-temperature storage from the drive voltage before high-temperature storage).
The amount of change in the drive voltage obtained above is applied to the following formula, and the relative value of the amount of change in the drive voltage of each organic EL element with respect to the amount of change in the drive voltage of the organic EL element 2-1 is calculated as relative driving under high temperature storage. It was obtained as a voltage change.
Relative drive voltage change rate (%) under high temperature storage=(drive voltage change amount of each organic EL element/drive voltage change amount of organic EL element 2-1)×100
A smaller value indicates a more favorable result.

[Example 3]
(Production of organic EL element)
<Production of organic EL element 3-1>
A glass substrate having a size of 50 mm×50 mm and a thickness of 0.7 mm was ultrasonically cleaned with isopropyl alcohol. Then, after drying with dry nitrogen gas, this glass substrate was fixed to a substrate holder of a commercially available vacuum vapor deposition apparatus.

Each crucible for vapor deposition in the vacuum vapor deposition apparatus was filled with the constituent material of each layer in the optimum amount for device fabrication. A vapor deposition crucible was made of molybdenum or tungsten resistance heating material.
After reducing the pressure to a degree of vacuum of 1×10 ⁻⁴ Pa, a vapor deposition mask was attached to the glass substrate, and a vapor deposition crucible containing Al as an anode was energized and heated. Then, it was deposited on a glass substrate at a deposition rate of 0.1 nm/sec to form a patterned anode with a layer thickness of 100 nm.
Then, HAT-CN (1,4,5,8,9,12-hexaazatriphenylene hexacarbonitrile) was deposited on the anode at a deposition rate of 0.1 nm/sec to form a hole injection layer with a layer thickness of 10 nm. did.

Furthermore, α-NPD (4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl) was vapor-deposited on the hole injection layer at a vapor deposition rate of 0.1 nm/sec to obtain a layer thickness of 40 nm. of the hole transport layer was formed.
CBP as a host compound and Ir(ppy) ₃ as a light-emitting dopant were co-deposited at a deposition rate of 0.1 nm/sec so as to have volume percentages of 90% and 10%, respectively, to form a light-emitting layer having a layer thickness of 30 nm.

Thereafter, as an electron transport layer, Alq ₃ was deposited at a deposition rate of 0.1 nm/sec to form an electron transport layer having a layer thickness of 30 nm.
After that, comparative compound 3 and LiQ were co-deposited at a deposition rate of 0.1 nm/sec so as to have volume percentages of 50% and 50%, respectively, to form an electron injection layer having a layer thickness of 2 nm. Note that the electron injection layer corresponds to the thin film in the present invention.
Thereafter, silver was deposited at a deposition rate of 0.1 nm/sec to form a cathode with a film thickness of 15 nm.
The non-light-emitting surface side of the device was covered with a can-shaped glass case in an atmosphere of high-purity nitrogen gas with a purity of 99.999% or more, and an electrode extraction wiring was installed to prepare an organic EL device 3-1.

<Production of organic EL elements 3-2 to 3-21>
Organic EL devices 3-2 to 3- were prepared in the same manner as organic EL device 3-1 except that the compound of the electron injection layer, the ratio of silver and magnesium in the cathode, and the film thickness of the cathode were changed as shown in Table III. 21 was made.
In the organic EL devices 3-1 to 3-21, the electron injection layer contains 50% LiQ, but the notation of LiQ is omitted in Table III.

(evaluation)
(1) Measurement of Relative Driving Voltage For each organic EL element produced, the front luminance was measured on both the transparent electrode side (that is, transparent substrate side) and the counter electrode side (that is, cathode side) of each organic EL element. , and the voltage at which the sum was 1000 cd/m ² was measured as the driving voltage (V). A spectral radiance meter CS-1000 (manufactured by Konica Minolta) was used to measure luminance.
The drive voltage obtained above was applied to the following formula to obtain the relative drive voltage of each organic EL element with respect to the drive voltage of the organic EL element 3-1.
Relative driving voltage (%)=(driving voltage of each organic EL element/driving voltage of organic EL element 3-1)×100
A smaller value indicates a more favorable result.

(2) Measurement of relative drive voltage change under high-temperature storage The organic EL element produced above is caused to emit light at a temperature of 80° C. under a constant current condition of 2.5 mA/cm ² , and the drive voltage immediately after the start of light emission, The drive voltage was measured 100 hours after the start.
The obtained drive voltages before and after high-temperature storage were compared to determine the amount of change in drive voltage (the value obtained by subtracting the drive voltage after high-temperature storage from the drive voltage before high-temperature storage).
The amount of change in the drive voltage obtained above is applied to the following formula, and the relative value of the amount of change in the drive voltage of each organic EL element with respect to the amount of change in the drive voltage of the organic EL element 3-1 is calculated as relative driving under high temperature storage. It was obtained as a voltage change.
Relative drive voltage change rate (%) under high temperature storage=(drive voltage change amount of each organic EL element/drive voltage change amount of organic EL element 3-1)×100
A smaller value indicates a more favorable result.

[Example 4]
(Production of organic EL element)
<Production of organic EL element 4-1>
A 150 nm-thick film of ITO (indium tin oxide) was formed as an anode on a glass substrate of 50 mm×50 mm and 0.7 mm thick. After patterning, the transparent substrate with the ITO transparent electrode was ultrasonically cleaned with isopropyl alcohol. Then, it was dried with dry nitrogen gas and UV ozone cleaning was performed for 5 minutes. After that, this transparent substrate was fixed to a substrate holder of a commercially available vacuum vapor deposition apparatus.

Each crucible for vapor deposition in the vacuum vapor deposition apparatus was filled with the constituent material of each layer in the optimum amount for device fabrication. A vapor deposition crucible was made of molybdenum or tungsten resistance heating material.
After reducing the pressure to a degree of vacuum of 1×10 ⁻⁴ Pa, the vapor deposition crucible containing HAT-CN (1,4,5,8,9,12-hexaazatriphenylene hexacarbonitrile) was heated by energization. Then, it was vapor-deposited on the ITO transparent electrode at a vapor deposition rate of 0.1 nm/sec to form a first hole injection layer with a layer thickness of 20 nm.

Next, compound 4-A represented by the following structural formula was deposited on the first hole injection layer at a deposition rate of 0.1 nm/sec to form a first hole transport layer having a layer thickness of 50 nm.

Further, a compound 4-B represented by the following structural formula was deposited on the first hole transport layer at a deposition rate of 0.1 nm/sec to form an electron blocking layer with a layer thickness of 10 nm.

Compound 4-C represented by the following structural formula as a host compound of the first light-emitting layer, and compound 4-D as a blue fluorescent light-emitting dopant were deposited at a vapor deposition rate of 0.1 nm/sec so as to have volume percentages of 95% and 5%, respectively. Co-evaporation was performed to form a first light-emitting layer having a layer thickness of 30 nm.

Thereafter, as a first electron transport layer, compound 4-E represented by the following structural formula was deposited at a deposition rate of 0.1 nm/sec to form a first electron transport layer having a layer thickness of 30 nm.

Through the above steps, a first light-emitting unit composed of a first hole-transporting layer, an electron-blocking layer, a first light-emitting layer, and a first electron-transporting layer was produced.

Next, comparative compound 1 and Li were co-deposited at a deposition rate of 0.1 nm/sec so as to have a volume % of 95% and 5%, respectively, to form a charge generation layer having a layer thickness of 20 nm on the first electron transport layer. did. Note that the charge generation layer corresponds to the thin film in the present invention.

After that, HAT-CN (1,4,5,8,9,12-hexaazatriphenylene hexacarbonitrile) was deposited on the charge generation layer at a deposition rate of 0.1 nm/sec in the same manner as the first hole transport layer. vapor deposition to form a second hole injection layer with a thickness of 20 nm. Then, compound 4-A was deposited on the second hole injection layer at a deposition rate of 0.1 nm/sec to form a second hole transport layer having a layer thickness of 60 nm.
Compound 4-F represented by the following structural formula as a host compound of the second emitting layer, Ir(ppy) ₃ as a green phosphorescent dopant, and Ir(piq) ₃ (Tris[1-phenylisoquinoline-C ² ) as a red phosphorescent dopant , N]iridium(III)) were co-deposited at a deposition rate of 0.1 nm/sec to a volume percentage of 79%, 20%, and 1%, respectively, to form a second light-emitting layer having a layer thickness of 20 nm.

Thereafter, compound 4-E was vapor-deposited at a vapor deposition rate of 0.1 nm/sec in the same manner as for the first electron-transporting layer to form a second electron-transporting layer having a layer thickness of 30 nm.
Further, LiQ was vapor-deposited at a vapor deposition rate of 0.1 nm/sec to form an electron injection layer with a film thickness of 2 nm, and then aluminum was vapor-deposited at a vapor deposition rate of 0.1 nm/sec to form a cathode with a layer thickness of 100 nm. The non-light-emitting surface side of was covered with a can-shaped glass case in an atmosphere of high-purity nitrogen gas with a purity of 99.999% or more, and an electrode extraction wiring was installed to prepare an organic EL device 4-1.

<Production of organic EL elements 4-2 to 4-11>
Organic EL devices 4-2 to 4-11 were produced in the same manner as organic EL device 4-1, except that the compounds in the charge generation layer were changed as shown in Table IV.
In the organic EL elements 4-1 to 4-11, the charge generation layer contains 5% Li, but the notation of Li is omitted in Table IV.

(evaluation)
(1) Measurement of Relative Driving Voltage For each organic EL element produced, the front luminance was measured on both the transparent electrode side (that is, transparent substrate side) and the counter electrode side (that is, cathode side) of each organic EL element. , and the voltage at which the sum was 1000 cd/m ² was measured as the driving voltage (V). A spectral radiance meter CS-1000 (manufactured by Konica Minolta) was used to measure luminance.
The drive voltage obtained above was applied to the following formula to obtain the relative drive voltage of each organic EL element with respect to the drive voltage of the organic EL element 4-1.
Relative driving voltage (%)=(driving voltage of each organic EL element/driving voltage of organic EL element 4-1)×100
A smaller value indicates a more favorable result.

(2) Measurement of relative drive voltage change under high-temperature storage The organic EL element produced above is caused to emit light at a temperature of 80° C. under a constant current condition of 2.5 mA/cm ² , and the drive voltage immediately after the start of light emission, The drive voltage was measured 100 hours after the start.
The obtained drive voltages before and after high-temperature storage were compared to determine the amount of change in drive voltage (the value obtained by subtracting the drive voltage after high-temperature storage from the drive voltage before high-temperature storage).
The amount of change in the drive voltage obtained above is applied to the following formula, and the relative value of the amount of change in the drive voltage of each organic EL element with respect to the amount of change in the drive voltage of the organic EL element 4-1 is calculated as relative driving under high temperature storage. It was obtained as a voltage change.
Relative drive voltage change rate (%) under high temperature storage=(drive voltage change amount of each organic EL element/drive voltage change amount of organic EL element 4-1)×100
A smaller value indicates a more favorable result.

As described above, the organic EL element of the present invention has a lower relative driving voltage than the organic EL element of the comparative example, and a small change in relative driving voltage under high temperature storage, so it is excellent in stability during high temperature storage and has excellent durability. It turned out to be excellent.

In order to improve the performance of electronic devices, the present invention provides a thin film, an electronic device, an organic electroluminescent element, an organic electroluminescent material, a display device, and, It can be used for lighting devices.

1 Display 3 Pixel 5 Scanning Line 6 Data Line 7 Power Supply Line 10 Organic EL Element 11 Switching Transistor 12 Drive Transistor 13 Capacitor 101 Organic EL Element in Lighting Device 102 Glass Cover 105 Cathode 106 Organic Functional Layer 107 Glass Substrate with Transparent Electrode 108 Nitrogen Gas 109 Water capturing agent A Display unit B Control unit C Wiring unit L Emitted light

Claims (11)

A thin film containing a compound having a structure represented by the following general formula (1).

(In the general formula (1), Ar ₁ to Ar ₃ each independently represent a hydrogen atom, an aromatic hydrocarbon ring or a heterocyclic ring, and at least one is a pyridine ring, a pyrazine ring, a pyrimidine ring, or a quinazoline Each of Ar ₄ to Ar ₆ independently represents a hydrogen atom, an aromatic hydrocarbon ring or a heterocyclic ring, and at least one represents a pyridine ring, pyrazine ring, pyrimidine ring or quinazoline ring. n represents an integer of 3 or more and 5 or less, and each L independently represents a phenyl ring, a pyridine ring or a pyrimidine ring .) 2. The thin film of claim 1, which is used adjacent to a silver thin film containing silver. 3. The thin film of claim 1 or 2 , further comprising an electron injection material. An organic electroluminescent element having an electrode and a plurality of organic functional layers including a light-emitting layer,
An organic electroluminescence device, wherein at least one layer of the organic functional layer is the thin film according to any one of claims 1 to 3 . 5. The organic electroluminescence device according to claim 4 , wherein the thin film, the electron injection layer, and the electrode are laminated in this order. The electrode is mainly composed of silver,
6. The organic electroluminescence device according to claim 4 , wherein said organic functional layer is provided adjacent to said electrode. 7. The organic electroluminescence element according to any one of claims 4 to 6 , wherein the electrode has a film thickness of 15 nm or less and is transparent. An organic electroluminescence material containing a compound having a structure represented by the following general formula (1).

(In the general formula (1), Ar ₁ to Ar ₃ each independently represent a hydrogen atom, an aromatic hydrocarbon ring or a heterocyclic ring, and at least one is a pyridine ring, a pyrazine ring, a pyrimidine ring, or a quinazoline Each of Ar ₄ to Ar ₆ independently represents a hydrogen atom, an aromatic hydrocarbon ring or a heterocyclic ring, and at least one represents a pyridine ring, pyrazine ring, pyrimidine ring or quinazoline ring. n represents an integer of 3 or more and 5 or less, and each L independently represents a phenyl ring, a pyridine ring or a pyrimidine ring .) A display device comprising the organic electroluminescence element according to any one of claims 4 to 7 . A lighting device comprising the organic electroluminescence element according to any one of claims 4 to 7 . An electronic device comprising an electrode and a thin film according to any one of claims 1 to 3 .

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