JP5463701B2 - Method for producing composition for organic electroluminescent device, composition for organic electroluminescent device, organic electroluminescent device, organic EL display and organic EL lighting - Google Patents

Description

The present invention relates to a method for producing a composition for organic electroluminescent elements, and a composition for organic electroluminescent elements produced by the production method.
The present invention also relates to an organic electroluminescent device having an organic layer formed using the above composition, an organic EL display including the organic electroluminescent device, and organic EL lighting.

The demand for high-visibility and high-quality display elements is increasing ahead of the full transition to digital broadcasting. At present, organic electroluminescence (EL) is abbreviated as “EL” as the next generation display element. The device is drawing attention.
Although it is an organic electroluminescent device that has advantages such as thin, low voltage, high contrast, high-speed response, and wide viewing angle, its practical application to small and medium-sized displays is progressing, and it is used as a display for mobile phones and portable music players. There are more opportunities to see in town. Currently, development is underway for practical use in large displays such as televisions.

In many cases, the organic layer of an organic electroluminescence device put into practical use is formed by laminating a low molecular weight dye or the like by vacuum deposition. However, it is difficult to form a uniform film over a large area by the vacuum deposition method, and there is a problem in manufacturing a large-area display. On the other hand, a manufacturing method has been proposed in which a plurality of organic layers of a stacked organic electroluminescent element are formed by a wet film forming method such as a spin coating method, an ink jet method, or various printing methods.
However, organic light-emitting device manufactured by a wet film forming method, compared to the organic electroluminescent device fabricated by vacuum deposition tends to light emission efficiency and driving lifetime is lowered, there is a problem that .

Japanese Patent No. 3069139 Japanese Patent Laid-Open No. 11-238359

  The present invention relates to a composition for an organic electroluminescent device comprising a low molecular weight compound and a solvent, and the durability of the organic electroluminescent device having an organic layer formed by using the composition is improved and the lifetime is increased. Composition for organic electroluminescence device that can be achieved, method for producing the same, organic electroluminescent device having high durability and long life having an organic layer formed using the composition, method for producing the same, and organic It is an object to provide an EL display and organic EL lighting.

The present inventors have a result of intensive studies, the wet film formation method The organic electroluminescent device manufactured by tends to be compared to the organic electroluminescent device fabricated by vacuum deposition light emission efficiency and driving lifetime decreases The cause was found as follows.
First, it is conceivable that the structural form formed by the components contained in the organic layer formed by the wet film forming method is different from the structural form in the organic layer formed by the vacuum deposition method.

That is, when the same material is used, it is estimated that the density of the organic layer formed by the wet film forming method is lower than the density of the organic layer formed by the vacuum deposition method.
This is considered to be due to the fact that the components in the organic layer formed by the wet film forming method are in an aggregated state, and the density in the organic layer is unevenly distributed. Furthermore, when an organic layer is formed by a wet film-forming method using a composition containing a solvent, segregation of each component is presumed to be one of the above causes.

As a result of further examination based on these findings, using a composition produced by a production method comprising a step of heating at a specific temperature condition after mixing the low molecular compound component and the solvent component of the composition, The inventors have found that the above problems can be solved by forming an organic layer, and have reached the present invention.
That is, the present invention provides a composition for organic electroluminescence element containing a solvent emitting low molecular compound, after mixing a part or the whole of the light-emitting low molecular weight material and a solvent component, 100 ° C. or higher in, and characterized in that it comprises a step of heating the lower temperature range 10 ° C. or higher than the boiling point of the most boiling lower solvent component contained in the mixture, that Sons the manufacturing method of the organic electroluminescence element composition .

The present invention also resides in an organic electroluminescent element composition, an organic electroluminescent element, an organic EL display, and an organic EL illumination manufactured by the method for manufacturing an organic electroluminescent element composition.

  An organic electroluminescence device having an organic layer formed by a wet film-forming method using the composition produced by the method for producing a composition for an organic electroluminescence device of the present invention has a high luminance and a driving life. A long organic electroluminescent element is obtained.

It is sectional drawing which shows typically an example of the structure of the organic electroluminescent element of this invention.

Embodiments of the present invention will be described in detail below. However, the description of the constituent elements described below is an example (representative example) of an embodiment of the present invention, and the present invention is not limited to these contents. Not.
The first method for producing a composition for an organic electroluminescent device of the present invention is a method for producing a composition for an organic electroluminescent device containing a low molecular compound and a solvent, the low molecular compound and the solvent of the composition. And a step of heating the mixture in a temperature range of 60 ° C. or more and 10 ° C. or more lower than the boiling point of the solvent having the lowest boiling point contained in the mixture. It is a manufacturing method of a thing.

  The second method for producing a composition for an organic electroluminescent element of the present invention is a method for producing a composition for an organic electroluminescent element containing a low molecular compound and a solvent, and the low molecular compound of the composition It is a manufacturing method of the composition for organic electroluminescent elements characterized by including the process of ultrasonically vibrating the mixture which mixed the solvent with the solvent.

<Configuration>
The composition for organic electroluminescent elements of the present invention is a composition containing a low molecular compound and a solvent.
[Low molecular compounds]
The low molecular weight compound in the present invention refers to a compound defined by a single molecular weight.
The low molecular weight compound is preferably the following light emitting low molecular weight compound and / or charge transporting low molecular weight compound.
[Luminescent low molecular weight compound]
The composition for organic electroluminescent elements of the present invention preferably contains a light-emitting low molecular compound as the low molecular compound.

The light emitting low molecular compound is not particularly limited as long as it is a compound having a light emitting property defined by a single molecular weight, and a known material can be applied. For example, it may be a fluorescent low molecular weight compound or a phosphorescent low molecular weight compound, but from the viewpoint of internal quantum efficiency, it is preferably a phosphorescent low molecular weight compound.
In order to improve the solubility in a solvent, it is preferable to reduce the symmetry and rigidity of the molecule of the light-emitting low molecular weight compound or to introduce a lipophilic substituent such as an alkyl group.

Hereinafter, examples of the fluorescent light-emitting low molecular compound among the light-emitting low molecular compounds will be described, but the fluorescent light-emitting low molecular compound is not limited to the following examples.
Although the example of a fluorescent light-emitting material is given among light-emitting materials, a fluorescent light-emitting material is not limited to the following illustrations.
Examples of the fluorescent light-emitting material that gives blue light emission (blue fluorescent light-emitting material) include naphthalene, perylene, pyrene, anthracene, coumarin, chrysene, p-bis (2-phenylethenyl) benzene, and derivatives thereof.

Examples of the fluorescent light emitting material that gives green light emission (green fluorescent light emitting material) include quinacridone derivatives, coumarin derivatives, aluminum complexes such as Al (C ₉ H ₆ NO) _3, and the like.
Examples of the fluorescent light-emitting material that gives yellow light (yellow fluorescent light-emitting material) include rubrene and perimidone derivatives.

  Examples of fluorescent light-emitting materials (red fluorescent light-emitting materials) that emit red light include, for example, DCM (4- (dicyanomethylene) -2-methyl-6- (p-dimethylaminostyryl) -4H-pyran) -based compounds, benzopyran derivatives, rhodamine derivatives. Benzothioxanthene derivatives, azabenzothioxanthene and the like.

As the phosphorescent material, for example, a long-period type periodic table (hereinafter referred to as a long-period type periodic table when referred to as “periodic table” unless otherwise specified) is selected from the seventh to eleventh groups. And an organometallic complex containing a metal.
Preferred examples of the metal selected from Groups 7 to 11 of the periodic table include ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum, and gold.

  As the ligand of the complex, a ligand in which a (hetero) aryl group such as a (hetero) arylpyridine ligand or a (hetero) arylpyrazole ligand and a pyridine, pyrazole, phenanthroline, or the like is connected is preferable. A pyridine ligand and a phenylpyrazole ligand are preferable. Here, (hetero) aryl represents an aryl group or a heteroaryl group.

  Specific examples of the phosphorescent material include tris (2-phenylpyridine) iridium, tris (2-phenylpyridine) ruthenium, tris (2-phenylpyridine) palladium, bis (2-phenylpyridine) platinum, tris (2- Phenylpyridine) osmium, tris (2-phenylpyridine) rhenium, octaethyl platinum porphyrin, octaphenyl platinum porphyrin, octaethyl palladium porphyrin, octaphenyl palladium porphyrin, and the like.

  The molecular weight of the compound used as the light emitting material is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 10,000 or less, preferably 5000 or less, more preferably 4000 or less, still more preferably 3000 or less, and usually 100 or more, Preferably it is 200 or more, More preferably, it is 300 or more, More preferably, it is the range of 400 or more. If the molecular weight of the luminescent material is too small, the heat resistance will be significantly reduced, gas generation will be caused, the film quality will be reduced when the film is formed, or the morphology of the organic electroluminescent element will be changed due to migration, etc. Sometimes come. On the other hand, if the molecular weight of the luminescent material is too large, it tends to be difficult to purify the luminescent material, or it may take time to dissolve in the solvent.

In addition, any 1 type may be used for the luminescent material mentioned above, and 2 or more types may be used together by arbitrary combinations and a ratio.
Specific examples of the light emitting low molecular weight compound are shown below, but the present invention is not limited to these. Hex represents a hexyl group.
<Examples of luminescent low molecular weight compounds>

[Charge transporting low molecular weight compounds]
The composition for organic electroluminescent elements of the present invention preferably contains a charge transporting low molecular weight compound as the low molecular weight compound.
In the present invention, only one kind of charge transporting low molecular weight compound may be used, or two or more kinds may be used in any combination and ratio.

The organic electroluminescent element of the present invention has a light emitting layer formed using the composition, and in the light emitting layer, a light emitting material is used as a dopant material, and a charge transporting low molecular weight compound is used as a host material. Is preferred.
The charge transporting low molecular weight compound may be a compound that has been conventionally used in a light emitting layer of an organic electroluminescence device, and particularly a compound that is used as a host material of the light emitting layer.

  Specific examples of charge transporting low molecular weight compounds include aromatic amine compounds, phthalocyanine compounds, porphyrin compounds, oligothiophene compounds, polythiophene compounds, benzylphenyl compounds, and compounds in which tertiary amines are linked by a fluorene group. , Hydrazone compounds, silazane compounds, silanamine compounds, phosphamine compounds, quinacridone compounds, anthracene compounds, pyrene compounds, carbazole compounds, pyridine compounds, phenanthroline compounds, oxadiazole compounds, silole compounds Etc.

For example, two or more condensed aromatic rings including two or more tertiary amines represented by 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl are substituted with nitrogen atoms. Aromatic amine compounds having a starburst structure (J. Lumin, etc.) such as aromatic diamines (Japanese Patent Laid-Open No. 5-234681), 4,4 ′, 4 ″ -tris (1-naphthylphenylamino) triphenylamine, etc. , 72-74, 985, 1997), an aromatic amine compound comprising a tetramer of triphenylamine (Chem. Commun., 2175, 1996), 2, 2 ′, 7, 7 ′. -Fluorene compounds such as tetrakis- (diphenylamino) -9,9'-spirobifluorene (Synth. Metals, 91, 209, 1997), 4,4'-N, N'- Carbazole compounds such as carbazole biphenyl, 2- (4-biphenylyl) -5- (p-tertiarybutylphenyl) -1,3,4-oxadiazole (tBu-PBD), 2,5-bis (1- Oxadiazole compounds such as naphthyl) -1,3,4-oxadiazole (BND), 2,5-bis (6 ′-(2 ′, 2 ″ -bipyridyl))-1,1-dimethyl-3 Silole compounds such as 1,4-diphenylsilole (PyPySPyPy), phenanthroline compounds such as bathophenanthroline (BPhen), 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP, bathocuproin), etc. It is done.

Specific examples of the charge transporting low molecular weight compound are shown below, but the present invention is not limited thereto. In the formula, Bu represents a butyl group, and Et represents an ethyl group.
<Examples of charge transporting low molecular weight compounds>

[solvent]
Moreover, a solvent will not be specifically limited if it is a solvent in which a luminescent low molecular weight compound and a charge transporting low molecular weight compound dissolve favorably.
The solubility of the solvent is usually 0.01% by weight or more, preferably 0.05% by weight or more, and more preferably 0% of the light-emitting low molecular weight compound and the charge transporting low molecular weight compound at normal temperature and normal pressure, respectively. It is preferable to dissolve 1% by weight or more.

Although the specific example of a solvent is given to the following, as long as the effect of this invention is not impaired, it is not limited to these.
For example, alkanes such as n-decane, cyclohexane, ethylcyclohexane, decalin, and bicyclohexane; aromatic hydrocarbons such as toluene, xylene, methicylene, cyclohexylbenzene, and tetralin; halogenated fragrances such as chlorobenzene, dichlorobenzene, and trichlorobenzene Group hydrocarbons: 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, anisole, phenetole, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole, 2,4-dimethyl Aromatic ethers such as anisole and diphenyl ether; aromatic esters such as phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, ethyl benzoate, propyl benzoate, and n-butyl benzoate; Alicyclic ketones such as Sanone, Cyclooctanone and Fencon; Alicyclic alcohols such as cyclohexanol and cyclooctanol; Aliphatic ketones such as methyl ethyl ketone and dibutyl ketone; Aliphatic alcohols such as butanol and hexanol; Ethylene And aliphatic ethers such as glycol dimethyl ether, ethylene glycol diethyl ether, and propylene glycol-1-monomethyl ether acetate (PGMEA).

Of these, alkanes and aromatic hydrocarbons are preferable. One of these solvents may be used alone, or two or more thereof may be used in any combination and ratio.
In order to obtain a more uniform film, it is preferable that the solvent evaporates from the liquid film immediately after the film formation at an appropriate rate. For this reason, the boiling point of the solvent is usually 80 ° C. or higher, preferably 100 ° C. or higher, more preferably 120 ° C. or higher, and usually 270 ° C. or lower, preferably 250 ° C. or lower, more preferably 230 ° C. or lower.

The amount of the solvent used is arbitrary as long as the effect of the present invention is not significantly impaired, but is preferably 10 parts by weight or more, more preferably 50 parts by weight or more, particularly preferably 100 parts by weight or more with respect to 100 parts by weight of the organic electroluminescent element composition. The amount is preferably 80 parts by weight or more, preferably 99.95 parts by weight or less, more preferably 99.9 parts by weight or less, and particularly preferably 99.8 parts by weight or less. When the content is lower than the lower limit, the viscosity becomes too high, and the film forming workability may be lowered. On the other hand, when the value exceeds the upper limit, the film thickness obtained by removing the solvent after film formation cannot be obtained, so that film formation tends to be difficult. In addition, when mixing 2 or more types of solvents as a composition for organic electroluminescent elements, it is made for the sum total of these solvents to satisfy | fill this range.
Moreover, the composition for organic electroluminescent elements in this invention may contain various additives, such as a leveling agent and an antifoamer, for the purpose of improving film forming property.

(Others may be included)
The composition for organic electroluminescent elements of the present invention may contain a surfactant, a viscosity adjusting agent, filler particles and the like in addition to the low molecular compound.
As the surfactant, various types such as anionic, cationic, nonionic, and amphoteric surfactants can be used, but nonionic is preferable in that it has a low possibility of adversely affecting electrical characteristics. It is preferable to use a surfactant.
Examples of the anionic surfactant include alkyl sulfate ester surfactants such as “Emar 10” (manufactured by Kao Corporation), alkyl naphthalene sulfonate surfactants such as “Perex NB-L”, and the like. Special polymeric surfactants such as “Homogenol L-18”, “Homogenol L-100” and the like can be mentioned. Of these, special polymer surfactants are preferred, and special polycarboxylic acid type polymer surfactants are more preferred.

Examples of the cationic surfactant include alkylamine salt surfactants such as “Acetamine 24” (manufactured by Kao Corporation), and quaternary ammonium salt interfaces such as “Cotamine 24P” and “Cotamine 86W”. Examples include activators. Of these, quaternary ammonium salt surfactants are preferred, and stearyltrimethylammonium salt surfactants are more preferred.

  Examples of the nonionic surfactant include silicone surfactants such as “SH8400” (manufactured by Torre Silicone), “KP341” (manufactured by Silicone), “FC430” (manufactured by Sumitomo 3M), Fluorine surfactants such as “F470” (Dainippon Ink Chemical Co., Ltd.), “DFX-18” (Neos), etc., “Emulgen 104P” (Kao Corporation), polyoxyethylene such as “Emulgen A60” And surface active agents. Of these, silicone surfactants are preferable, and so-called polyether-modified or aralkyl-modified silicone surfactants having a structure in which a side chain of a polyether group or an aralkyl group is added to polydimethylsiloxane are more preferable.

  Two or more kinds of surfactants may be combined. Silicone surfactant / fluorine surfactant, silicone surfactant / special polymer surfactant, fluorine surfactant / special polymer surfactant Examples include combinations of agents. Of these, silicone surfactants / fluorine surfactants are preferred. Examples of the silicone surfactant / fluorine surfactant combination include polyether-modified silicone surfactant / oligomer-type fluorine surfactant. Specifically, for example, “TSF4460” (manufactured by GE Toshiba Silicone) / “DFX-18” (manufactured by Neos), “BYK-300” (manufactured by BYK Chemie) / “S-393” (manufactured by Seimi Chemical) ), “KP340” (manufactured by Shin-Etsu Silicone) / “F-478” (manufactured by Dainippon Ink & Co.), “SH7PA” (manufactured by Tore Silicone) / “DS-401” (manufactured by Daikin), “L-77” (Nihon Unicar Co., Ltd.) / "FC4430" (Sumitomo 3M Co., Ltd.).

The content of the surfactant in the composition for organic electroluminescent elements of the present invention is usually 0.01% by weight or more, preferably 0.05% by weight or more, and usually 1% by weight or less, preferably 0.2% by weight. It is as follows.
Moreover, in order to adjust a viscosity, the viscosity modifier may be contained. Examples of the viscosity modifier include polymer thickeners such as polystyrene, polyurethane, and polyamide, and solvent-type diluents such as high-boiling aromatics, ketones, and esters.

The content of the viscosity modifier in the organic electroluminescent device composition of the present invention is usually 0.01% by weight or more, preferably 0.05% by weight or more, and usually 1% by weight or less, preferably 0.2% by weight. It is as follows.
In addition, filler particles may be included for adjusting the coating thickness and electrical characteristics. Examples of the filler particles include organic pigments such as phthalocyanine and anthraquinone, and inorganic pigments such as silica and titanium oxide.
The content of the filler particles in the composition for organic electroluminescent elements of the present invention is usually 0.01% by weight or more, preferably 0.05% by weight or more, and usually 1% by weight or less, preferably 0.5% by weight or less. It is.

<The 1st manufacturing method of the composition for organic electroluminescent elements>
The first composition for an organic electroluminescent device of the present invention is a mixture obtained by mixing the above-described blending components blended in the composition at 60 ° C. or higher, and 10 ° C. lower than the lowest boiling point of the solvent mixed in the mixture. Manufactured by including a heating step at a lower temperature or lower.
The heating step may be carried out in such a state that the low molecular compound is dissolved in the solvent so as to be invisible or can be visually confirmed.
The heating temperature in the present invention is usually 60 ° C. or higher, preferably 100 ° C. or higher, more preferably 130 ° C. or higher, and usually 10 ° C. or lower, preferably 30 ° C. lower than the lowest boiling point of the solvents contained in the mixture. Below, it is 50 degrees C or less more preferably.

Within the above range, the movement of solvent molecules becomes intense due to heat, so the effect of dispersing low molecular compound molecules in the solvent is high, and the solvent does not boil, and has an effect on low molecular compound molecules. It is preferable at the point which can suppress as much as possible.
The heating temperature may be constant or may be varied within the above range.

The heating time in the present invention is usually 5 minutes, preferably 30 minutes or more, more preferably 1 hour or more, and usually 10 hours or less, preferably 5 hours or less, more preferably 2 hours or less.
Within the above range, it is preferable in that it is a time sufficient to uniformly disperse low molecular compound molecules in a solvent and can be produced with high productivity in as short a time as possible.

The heating means is not particularly limited, but a hot plate or an oil bath that can control the temperature can be used for heating the composition.
In the heating atmosphere, it is preferable to keep the oxygen concentration in the atmosphere in the container containing the composition at 100 ppm or less in order to prevent oxidation of the composition when heating. Moreover, since the mixing of moisture into the composition may cause a decrease in performance, the moisture concentration in the atmosphere in the container containing the composition is preferably set to 100 ppm or less.

<Additional solvent>
A solvent having a function other than dissolving the low-molecular compound can be added to the solvent of the composition for organic electroluminescent elements of the present invention. For example, in order to increase the evaporation rate of the solvent, a solvent having a lower boiling point may be added. Thus, when the boiling point of the added solvent is lower than the boiling point of the main solvent that dissolves the low-molecular compound, the heating temperature can be maintained at a high temperature by adding after the completion of the heating.
Examples of the additional solvent include tridecane, dodecane, 3-methylundecane, 2,2,4,6,6-pentamethylheptane, decane, 2-methylnonane, 3-methylnonane, 4-methylnonane, 5-methylnonane, and the like. Is mentioned.

<The 2nd manufacturing method of the composition for organic electroluminescent elements>
The second method for producing a composition for an organic electroluminescent device of the present invention is a method for producing a composition for an organic electroluminescent device containing a low molecular compound and a solvent, the low molecular compound and the solvent of the composition. And a step of ultrasonically vibrating the mixture.
The ultrasonic vibration means in the present invention is not particularly limited, but an ultrasonic generator such as an ultrasonic cleaner can be used.
The vibration conditions in the present invention are usually 15 kHz or more, preferably 20 kHz or more, more preferably 28 kHz or more, and usually 400 kHz or less, preferably 200 kHz or less, more preferably 100 kHz or less, while varying within this range. It is more preferable to apply ultrasonic waves.

At low frequencies, large structures can be made finer by shock waves generated by bursting bubbles generated in the solvent, and at higher frequencies, they can act on finer structures. By varying the frequency, it is possible to act on structures in a wide range of sizes.
The vibration time in the present invention is usually 1 minute or longer, preferably 5 minutes or longer, more preferably 10 minutes or longer, and usually 1 hour or shorter, preferably 30 minutes or shorter, more preferably 15 minutes or shorter.

Within the above range, it is preferable in that it is a time sufficient to uniformly disperse low molecular compound molecules in a solvent and can be produced with high productivity in as short a time as possible.
In the vibration atmosphere of the present invention, since the ultrasonic irradiation is performed by immersing the container containing the composition in water, the composition is put in a tightly sealed container in order to prevent moisture from entering the composition. It is preferable to keep it. Furthermore, it is preferable to keep the atmosphere in the container at a moisture concentration of 100 ppm or less and an oxygen concentration of 100 ppm or less.

<Organic electroluminescent device>
Below, the layer structure of the organic electroluminescent element manufactured by the method of the present invention, its general formation method and the like will be described with reference to FIG.
FIG. 1 is a schematic cross-sectional view showing a structural example of an organic electroluminescent device according to the present invention. In FIG. 1, 1 is a substrate, 2 is an anode, 3 is a hole injection layer, 4 is a hole transport layer, 5 Represents a light-emitting layer, 6 represents a hole blocking layer, 7 represents an electron transport layer, 8 represents an electron injection layer, and 9 represents a cathode.
In the present invention, the wet film forming method includes, for example, spin coating method, dip coating method, die coating method, bar coating method, blade coating method, roll coating method, spray coating method, capillary coating method, ink jet method, nozzle printing. A method of forming a film by a wet method such as a printing method, a screen printing method, a gravure printing method, or a flexographic printing method. Among these film forming methods, a spin coating method, a spray coating method, a nozzle printing method, and an ink jet method are preferable, and among these, a nozzle printing method and an ink jet method are particularly preferable. This is because the liquid property specific to the coating composition used for the organic electroluminescent element is matched.

(substrate)
The substrate 1 serves as a support for the organic electroluminescent element, and a quartz or glass plate, a metal plate or a metal foil, a plastic film, a sheet, or the like is used. In particular, a glass plate or a transparent synthetic resin plate such as polyester, polymethacrylate, polycarbonate, polysulfone or the like is preferable. When using a synthetic resin substrate, it is necessary to pay attention to gas barrier properties. If the gas barrier property of the substrate is too small, the organic electroluminescent element may be deteriorated by the outside air that has passed through the substrate, which is not preferable. For this reason, a method of providing a gas barrier property by providing a dense silicon oxide film or the like on at least one surface of the synthetic resin substrate is also a preferable method.

(anode)
The anode 2 serves to inject holes into the layer on the light emitting layer side.
This anode 2 is usually a metal such as aluminum, gold, silver, nickel, palladium, platinum, a metal oxide such as an oxide of indium and / or tin, a metal halide such as copper iodide,
It is composed of carbon black or a conductive polymer such as poly (3-methylthiophene), polypyrrole, or polyaniline.
In general, the anode 2 is often formed by a sputtering method, a vacuum deposition method, or the like. In addition, when forming the anode 2 using fine metal particles such as silver, fine particles such as copper iodide, carbon black, conductive metal oxide fine particles, and conductive polymer fine powder, an appropriate binder resin solution It is also possible to form the anode 2 by dispersing it and applying it onto the substrate 1. Furthermore, in the case of a conductive polymer, a thin film can be directly formed on the substrate 1 by electrolytic polymerization, or the anode 2 can be formed by applying a conductive polymer on the substrate 1 (Appl. Phys. Lett. 60, 2711, 1992).

The anode 2 usually has a single-layer structure, but it can also have a laminated structure made of a plurality of materials if desired.
The thickness of the anode 2 varies depending on the required transparency. When transparency is required, the visible light transmittance is usually 60% or more, preferably 80% or more. In this case, the thickness of the anode 2 is usually 5 nm or more, preferably 10 nm or more, and is usually 1000 nm or less, preferably about 500 nm or less. When it may be opaque, the thickness of the anode 2 is arbitrary, and the anode 2 may be the same as the substrate 1. Furthermore, it is also possible to laminate different conductive materials on the anode 2 described above.

  For the purpose of removing impurities adhering to the anode 2 and adjusting the ionization potential to improve the hole injection property, the surface of the anode 2 is treated with ultraviolet (UV) / ozone, or with oxygen plasma or argon plasma. It is preferable to do.

(Hole injection layer)
The hole injection layer 3 is a layer that transports holes from the anode 2 to the light emitting layer 5, and is usually formed on the anode 2.
The method for forming the hole injection layer 3 according to the present invention may be a vacuum deposition method or a wet film formation method, and is not particularly limited, but the hole injection layer 3 is formed by a wet film formation method from the viewpoint of reducing dark spots. It is preferable.
The thickness of the hole injection layer 3 is usually 5 nm or more, preferably 10 nm or more, and usually 1000 nm or less, preferably 500 nm or less.

<Formation of hole injection layer by wet film formation method>
When forming the hole injection layer 3 by wet film formation, the material for forming the hole injection layer 3 is usually mixed with an appropriate solvent (hole injection layer solvent) to form a film-forming composition (positive A composition for forming a hole injection layer), and applying the composition for forming a hole injection layer on a layer (usually an anode) corresponding to the lower layer of the hole injection layer 3 by an appropriate technique. The hole injection layer 3 is formed by coating and drying.

(Hole transporting compound)
The composition for forming a hole injection layer usually contains a hole transporting compound and a solvent as a constituent material of the hole injection layer.
The hole transporting compound is a compound having a hole transporting property that is usually used in a hole injection layer of an organic electroluminescence device, and may be a polymer compound or the like, a monomer or the like. Although it may be a low molecular weight compound, it is preferably a high molecular weight compound.
The hole transporting compound is preferably a compound having an ionization potential of 4.5 eV to 6.0 eV from the viewpoint of a charge injection barrier from the anode 2 to the hole injection layer 3. Examples of hole transporting compounds include aromatic amine derivatives, phthalocyanine derivatives, porphyrin derivatives, oligothiophene derivatives, polythiophene derivatives, benzylphenyl derivatives, compounds in which tertiary amines are linked by a fluorene group, hydrazone derivatives, silazane derivatives, silanamines Derivatives, phosphamine derivatives, quinacridone derivatives, polyaniline derivatives, polypyrrole derivatives, polyphenylene vinylene derivatives, polythienylene vinylene derivatives, polyquinoline derivatives, polyquinoxaline derivatives, carbon and the like.

In the present invention, the derivative includes, for example, an aromatic amine derivative, and includes an aromatic amine itself and a compound having an aromatic amine as a main skeleton. It may be a mer.
The hole transporting compound used as the material for the hole injection layer 3 may contain any one of these compounds alone, or may contain two or more. In the case of containing two or more kinds of hole transporting compounds, the combination is arbitrary, but one or more kinds of aromatic tertiary amine polymer compounds and one or two kinds of other hole transporting compounds. It is preferable to use the above in combination.

Among the above examples, an aromatic amine compound is preferable from the viewpoint of amorphousness and visible light transmittance, and an aromatic tertiary amine compound is particularly preferable. Here, the aromatic tertiary amine compound is a compound having an aromatic tertiary amine structure, and includes a compound having a group derived from an aromatic tertiary amine.
The type of the aromatic tertiary amine compound is not particularly limited, but from the viewpoint of uniform light emission due to the surface smoothing effect, a polymer compound having a weight average molecular weight of 1,000 or more and 1,000,000 or less (a polymerizable compound in which repeating units are linked) is further included. preferable. Preferable examples of the aromatic tertiary amine polymer compound include a polymer compound having a repeating unit represented by the following formula (I).

(In formula (I), Ar ¹ and Ar ² each independently represent an aromatic hydrocarbon group which may have a substituent or an aromatic heterocyclic group which may have a substituent. Ar ^{3 to} Ar ⁵ each independently represents an aromatic hydrocarbon group which may have a substituent or an aromatic heterocyclic group which may have a substituent. Represents a linking group selected from the group of linking groups, and among Ar ^{1 to} Ar ⁵ , two groups bonded to the same N atom may be bonded to each other to form a ring.

(In said each formula, Ar < ⁶ > -Ar < ¹⁶ > represents the aromatic heterocyclic group which may have a substituent or the aromatic hydrocarbon group which may have a substituent each independently. R ¹ and R ² each independently represents a hydrogen atom or an arbitrary substituent.))
As the aromatic hydrocarbon group and aromatic heterocyclic group of Ar ^{1 to} Ar ¹⁶ , a benzene ring, a naphthalene ring, a phenanthrene ring, a thiophene from the viewpoint of the solubility, heat resistance, hole injection / transport property of the polymer compound A group derived from a ring or a pyridine ring is preferred, and a group derived from a benzene ring or a naphthalene ring is more preferred.

The aromatic hydrocarbon group and aromatic heterocyclic group of Ar ^{1 to} Ar ¹⁶ may further have a substituent. The molecular weight of the substituent is usually 400 or less, preferably about 250 or less. As the substituent, an alkyl group, an alkenyl group, an alkoxy group, an aromatic hydrocarbon group, an aromatic heterocyclic group and the like are preferable.
When R ¹ and R ² are optional substituents, examples of the substituent include alkyl groups, alkenyl groups, alkoxy groups, silyl groups, siloxy groups, aromatic hydrocarbon groups, aromatic heterocyclic groups, and the like. .

Specific examples of the aromatic tertiary amine polymer compound having a repeating unit represented by the formula (I) include those described in International Publication No. 2005/089024.
In addition, as a hole transporting compound, a conductive polymer (PEDOT / PSS) obtained by polymerizing 3,4-ethylenedioxythiophene (3,4-ethylenedioxythiophene), a polythiophene derivative, in high molecular weight polystyrene sulfonic acid. Is also preferred. Moreover, the end of this polymer may be capped with methacrylate or the like.

  The concentration of the hole transporting compound in the composition for forming a hole injection layer is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.01% by weight or more, preferably in terms of film thickness uniformity. Is 0.1% by weight or more, more preferably 0.5% by weight or more, and usually 70% by weight or less, preferably 60% by weight or less, more preferably 50% by weight or less. If this concentration is too high, film thickness unevenness may occur, and if it is too low, defects may occur in the formed hole injection layer.

(Electron-accepting compound)
The composition for forming a hole injection layer preferably contains an electron accepting compound as a constituent material of the hole injection layer.
The electron-accepting compound is preferably a compound having an oxidizing power and the ability to accept one electron from the above-described hole transporting compound, specifically, a compound having an electron affinity of 4 eV or more is preferable, and 5 eV or more. The compound which is the compound of these is further more preferable.
Examples of such electron-accepting compounds include triarylboron compounds, metal halides, Lewis acids, organic acids, onium salts, salts of arylamines and metal halides, and salts of arylamines and Lewis acids. Examples thereof include one or more compounds selected from the group. More specifically, an onium salt substituted with an organic group such as 4-isopropyl-4′-methyldiphenyliodonium tetrakis (pentafluorophenyl) borate and triphenylsulfonium tetrafluoroborate (International Publication No. WO 2005/089024); High valent inorganic compounds such as iron (III) chloride (Japanese Patent Laid-Open No. 11-251067), ammonium peroxodisulfate; cyano compounds such as tetracyanoethylene, tris (pendafluorophenyl) borane (Japanese Patent Laid-Open No. 2003-31365) Aromatic boron compounds such as); fullerene derivatives; iodine; sulfonate ions such as polystyrene sulfonate ions, alkylbenzene sulfonate ions, camphor sulfonate ions, and the like.

These electron accepting compounds can improve the conductivity of the hole injection layer by oxidizing the hole transporting compound.
The content of the electron-accepting compound in the hole-injecting layer or the composition for forming a hole-injecting layer with respect to the hole-transporting compound is usually 0.1 mol% or more, preferably 1 mol% or more. However, it is usually 100 mol% or less, preferably 40 mol% or less.

(Other components)
As a material for the hole injection layer, other components may be further contained in addition to the above-described hole transporting compound and electron accepting compound as long as the effects of the present invention are not significantly impaired. Examples of other components include various light emitting materials, electron transporting compounds, binder resins, and coating property improving agents. In addition, only 1 type may be used for another component and it may use 2 or more types together by arbitrary combinations and ratios.

(solvent)
At least one of the solvents of the composition for forming a hole injection layer used in the wet film formation method is preferably a compound that can dissolve the constituent material of the hole injection layer. The boiling point of this solvent is usually 110 ° C. or higher, preferably 140 ° C. or higher, particularly 200 ° C. or higher, usually 400 ° C. or lower, and preferably 300 ° C. or lower. If the boiling point of the solvent is too low, the drying speed is too high and the film quality may be deteriorated. Further, if the boiling point of the solvent is too high, it is necessary to increase the temperature of the drying step, which may adversely affect other layers and the substrate.

Examples of the solvent include ether solvents, ester solvents, aromatic hydrocarbon solvents, amide solvents, and the like.
Examples of ether solvents include aliphatic ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and propylene glycol-1-monomethyl ether acetate (PGMEA); 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, anisole , Phenetole, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole, aromatic ethers such as 2,4-dimethylanisole, and the like.

Examples of the ester solvents, such as phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, propyl benzoate, aromatic ester le such as benzoic acid n- butyl.
The aromatic hydrocarbon solvent, for example, toluene, xylene, cyclohexylbenzene, 3-Gray propyl biphenyl, 1,2,3,4-tetramethyl benzene, 1,4-diisopropylbenzene, methylation naphthalene is .
Examples of the amide solvents, e.g., N, N-dimethylformamide, N, N-dimethyl acetamidine de like.
Other, can be used dimethyl sulfoxide.
These solvent may use only 1 type and may use 2 or more types by arbitrary combinations and a ratio.

(Film formation method)
After preparing the composition for forming the hole injection layer, the composition is applied on the layer corresponding to the lower layer of the hole injection layer 3 (usually the anode 2) by wet film formation, and dried. The hole injection layer 3 is formed.
The temperature in the film forming step is preferably 10 ° C. or higher, and preferably 50 ° C. or lower, in order to prevent film loss due to the formation of crystals in the composition.
Although the relative humidity in a film-forming process is not limited unless the effect of this invention is impaired remarkably, it is 0.01 ppm or more normally and 80% or less normally.
After the film formation, the film of the composition for forming a hole injection layer is usually dried by heating or the like. Examples of the heating means used in the heating step include a clean oven, a hot plate, infrared rays, a halogen heater, microwave irradiation and the like. Among them, a clean oven and a hot plate are preferable in order to uniformly apply heat to the entire film.

  The heating temperature in the heating step is preferably heated at a temperature equal to or higher than the boiling point of the solvent used in the composition for forming a hole injection layer as long as the effects of the present invention are not significantly impaired. In the case of a mixed solvent containing two or more types of solvents used in the hole injection layer, at least one type is preferably heated at a temperature equal to or higher than the boiling point of the solvent. In consideration of an increase in the boiling point of the solvent, the heating step is preferably performed at 120 ° C. or higher, preferably 410 ° C. or lower.

  In the heating step, the heating time is not limited as long as the heating temperature is not lower than the boiling point of the solvent of the composition for forming a hole injection layer and sufficient insolubilization of the coating film does not occur. Is less than a minute. If the heating time is too long, the components of the other layers tend to diffuse, and if it is too short, the hole injection layer tends to be inhomogeneous. Heating may be performed in two steps.

<Formation of hole injection layer by vacuum deposition>
When the hole injection layer 3 is formed by vacuum deposition, one or more of the constituent materials of the hole injection layer 3 (the aforementioned hole transporting compound, electron accepting compound, etc.) are placed in a vacuum vessel. Put in crucibles installed (in case of using two or more materials, put them in each crucible), evacuate the inside of the vacuum vessel to about 10 ⁻⁴ Pa with a suitable vacuum pump, and then heat the crucible (two types When using the above materials, heat each crucible) and evaporate by controlling the amount of evaporation (when using two or more materials, evaporate by independently controlling the amount of evaporation) and face the crucible Then, the hole injection layer 3 is formed on the anode 2 of the substrate placed on the substrate. In addition, when using 2 or more types of materials, the hole injection layer 3 can also be formed by putting those mixtures into a crucible, heating and evaporating.

The degree of vacuum at the time of vapor deposition is not limited as long as the effect of the present invention is not significantly impaired, but is usually 0.1 × 10 ⁻⁶ Torr (0.13 × 10 ⁻⁴ Pa) or more, usually 9.0 × 10 ⁻⁶ Torr. (12.0 × 10 ⁻⁴ Pa) or less. The deposition rate is not limited as long as the effect of the present invention is not significantly impaired, but is usually 0.1 Å / second or more and usually 5.0 Å / second or less. The film forming temperature at the time of vapor deposition is not limited as long as the effect of the present invention is not significantly impaired, but is preferably 10 ° C. or higher, preferably 50 ° C. or lower.

[Hole transport layer]
The hole transport layer of the present invention is formed on the hole injection layer.
When the hole transporting compound is a monomer, the molecular weight is usually 5000 or less, preferably 2500 or less, preferably 300 or more, more preferably 500 or more. If the molecular weight exceeds this upper limit, purification may be difficult due to the high molecular weight of impurities, and if the molecular weight is lower than this lower limit, the glass transition temperature, melting point, vaporization temperature, etc. will decrease, so heat resistance will be reduced. It may be severely damaged.

  When the hole transporting compound is an oligomer or a polymer, its weight average molecular weight is usually 3,000,000 or less, preferably 1,000,000 or less, more preferably 500,000 or less, and usually 1 5,000 or more, preferably 2,500 or more, more preferably 5,000 or more. If the molecular weight exceeds this upper limit, purification may be difficult due to the high molecular weight of impurities, and if the molecular weight is lower than this lower limit, film formability may be reduced, and the glass transition temperature, melting point, and vaporization temperature. , The heat resistance may be significantly impaired.

  When the hole transporting compound is an oligomer or a polymer, its dispersity Mw / Mn (Mw: weight average molecular weight, Mn: number average molecular weight) is usually 3.0 or less, preferably 2.5 or less, more preferably. Is 2.0 or less, preferably 1.0 or more, more preferably 1.1 or more, and particularly preferably 1.2 or more. If the degree of dispersion exceeds this upper limit, purification may become difficult, solvent solubility may decrease, and film formability may decrease.

  In addition, the weight average molecular weight (and number average molecular weight) in this invention is determined by SEC (size exclusion chromatography) measurement. In SEC measurement, the elution time is shorter for higher molecular weight components and the elution time is longer for lower molecular weight components, but using the calibration curve calculated from the elution time of polystyrene (standard sample) with a known molecular weight, the elution time of the sample is changed to the molecular weight. By converting, the weight average molecular weight (and number average molecular weight) is calculated.

(Structure)
The material for forming the hole transport layer is preferably a material having a high hole transport capability and capable of efficiently transporting the injected holes. Therefore, it is preferable that the ionization potential is small, the transparency to visible light is high, the hole mobility is large, the stability is high, and impurities that become traps are not easily generated during manufacturing or use. In many cases, since it is in contact with the light emitting layer, it is preferable not to quench the light emitted from the light emitting layer or to reduce the efficiency by forming an exciplex with the light emitting layer.

  As a material of such a hole transport layer, any material that has been conventionally used as a constituent material of a hole transport layer may be used. For example, as a hole transport compound used in the above-described hole injection layer What was illustrated is mentioned. Also, nitrogen-containing aromatic compound derivatives such as pyridine derivatives, pyrazine derivatives, pyrimidine derivatives, triazine derivatives, quinoline derivatives, phenanthroline derivatives, carbazole derivatives, phthalocyanine derivatives, porphyrin derivatives; triphenylamine derivatives; silole derivatives; oligothiophene derivatives, condensation Examples include polycyclic aromatic derivatives and metal complexes. Among them, nitrogen-containing aromatic derivatives such as pyridine derivatives, pyrazine derivatives, pyrimidine derivatives, triazine derivatives, quinoline derivatives, phenanthroline derivatives, carbazole derivatives; triphenylamine derivatives, silole derivatives, condensed polycyclic aromatic derivatives, metal complexes, etc. Particularly preferred are triphenylamine derivatives.

  In addition, for example, polyvinylcarbazole derivatives, polyarylamine derivatives, polyvinyltriphenylamine derivatives, polyfluorene derivatives, polyarylene derivatives, polyarylene ether sulfone derivatives containing tetraphenylbenzidine, polyarylene vinylene derivatives, polysiloxane derivatives, polythiophenes Derivatives, poly (p-phenylene vinylene) derivatives, and the like. These may be any of alternating copolymer compounds, random polymer compounds, block polymer compounds, and graft copolymer compounds. Further, it may be a polymer having a branched main chain and three or more terminal portions, or a so-called dendrimer.

Of these, polyarylamine derivatives and polyarylene derivatives are preferred.
The polyarylamine derivative is preferably a polymer compound containing a repeating unit represented by the following formula (II). In particular, it is preferably a polymer compound composed of a repeating unit represented by the following formula (II). In this case, Ar ^a or Ar ^b may be different in each repeating unit.

(In formula (II), Ar ^a and Ar ^b each independently represent an aromatic hydrocarbon group or an aromatic heterocyclic group which may have a substituent.)
Examples of the aromatic hydrocarbon group which may have a substituent include, for example, a benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetracene ring, pyrene ring, benzpyrene ring, chrysene ring, triphenylene ring, and acenaphthene. Examples include a group derived from a 6-membered monocyclic ring or a 2-5 condensed ring, such as a ring, a fluoranthene ring, a fluorene ring, and a group in which these rings are linked by a direct bond.

  Examples of the aromatic heterocyclic group which may have a substituent include a furan ring, a benzofuran ring, a thiophene ring, a benzothiophene ring, a pyrrole ring, a pyrazole ring, an imidazole ring, an oxadiazole ring, an indole ring, and a carbazole ring. , Pyrroloimidazole ring, pyrrolopyrazole ring, pyrrolopyrrole ring, thienopyrrole ring, thienothiophene ring, furopyrrole ring, furofuran ring, thienofuran ring, benzoisoxazole ring, benzoisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring, pyridazine Ring, pyrimidine ring, triazine ring, quinoline ring, isoquinoline ring, sinoline ring, quinoxaline ring, phenanthridine ring, benzimidazole ring, perimidine ring, quinazoline ring, quinazolinone ring, azulene ring, etc. ring Are those groups group and the rings of from 2-4 fused ring is linked by a direct bond or two or more rings.

From the viewpoints of solubility and heat resistance, Ar ^a and Ar ^b are each independently selected from the group consisting of a benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, triphenylene ring, pyrene ring, thiophene ring, pyridine ring, and fluorene ring. A group derived from a selected ring or a group formed by linking two or more benzene rings (for example, a biphenyl group or a terphenyl group) is preferable.
Among these, a group derived from a benzene ring (phenyl group), a group formed by connecting two benzene rings (biphenyl group), and a group derived from a fluorene ring (fluorenyl group) are preferable.

Examples of the substituent that the aromatic hydrocarbon group and aromatic heterocyclic group in Ar ^a and Ar ^b may have include an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an aryloxy group, an alkoxycarbonyl group, and a dialkyl. Examples thereof include an amino group, a diarylamino group, an acyl group, a halogen atom, a haloalkyl group, an alkylthio group, an arylthio group, a silyl group, a siloxy group, a cyano group, an aromatic hydrocarbon ring group, and an aromatic heterocyclic group.

As the polyarylene derivative, an arylene group such as an aromatic hydrocarbon group or an aromatic heterocyclic group which may have a substituent exemplified as Ar ^a or Ar ^b in the formula (II) is used as ^a repeating unit. The high molecular compound which has is mentioned.
As the polyarylene derivative, a polymer compound having a repeating unit consisting of the following formula (III-1) and / or the following formula (III-2) is preferable.

(In the formula (III-1), R ^a , R ^b , R ^c and R ^d are each independently an alkyl group, an alkoxy group, a phenylalkyl group, a phenylalkoxy group, a phenyl group, a phenoxy group, an alkylphenyl group, Represents an alkoxyphenyl group, an alkylcarbonyl group, an alkoxycarbonyl group, or a carboxy group, and t and s each independently represent an integer of 0 to 3. When t or s is 2 or more, they are contained in one molecule. A plurality of R ^a or R ^b may be the same or different, and adjacent R ^a or R ^b may form a ring.)

(In formula (III-2), R ^e and R ^f are each independently synonymous with R ^a , R ^b , R ^c or R ^d in formula (III-1) above. Independently represents an integer of 0 to 3. When r or u is 2 or more, a plurality of R ^e and R ^f contained in one molecule may be the same or different, and adjacent R ^e or A ring may be formed by R ^f, and X represents an atom or a group of atoms constituting a 5-membered ring or a 6-membered ring.)
Specific examples of X include an oxygen atom, a boron atom which may have a substituent, a nitrogen atom which may have a substituent, a silicon atom which may have a substituent, and a substituent. A phosphorus atom which may be substituted, a sulfur atom which may have a substituent, a carbon atom which may have a substituent, or a group formed by bonding these.

As the polyarylene derivative, in addition to the repeating unit composed of the above following formula (III-1) and / or on following formula (III-2), a further recurring unit represented by the following formula (III-3) It is preferable to have.

(In the formula (III-3), Ar ^{c to} Ar ^j each independently represents an aromatic hydrocarbon group or an aromatic heterocyclic group which may have a substituent. Independently represents 0 or 1.)
Specific examples of Ar ^{c to} Ar ^j are the same as Ar ^a and Ar ^b in the formula (II).

Specific examples of the above formulas (III-1) to (III-3) and specific examples of polyarylene derivatives include those described in JP-A-2008-98619.
In addition, as a hole transporting compound, a conductive polymer (PEDOT / PSS) obtained by polymerizing 3,4-ethylenedioxythiophene (3,4-ethylenedioxythiophene), a polythiophene derivative, in high molecular weight polystyrene sulfonic acid. Is also preferred. Moreover, the end of this polymer may be capped with methacrylate or the like.

(Non-solubilizing group)
The hole transporting compound according to the present invention is preferably a compound having an insolubilizing group in the above structure. That is, the hole transport layer is preferably a layer obtained by insolubilizing a compound having an insolubilizing group.
The insolubilizing group is a group that reacts by irradiation with heat and / or active energy rays, and is a group having an effect of lowering solubility in an organic solvent or water after the reaction than before the reaction.
In the present invention, the insolubilizing group is preferably a leaving group or a crosslinkable group.

(Cross-linking group)
In addition, the hole transporting compound according to the present invention has a crosslinkable group as an insolubilizing group, and the reaction with respect to the solvent before and after the reaction (insolubilizing reaction) caused by irradiation with heat and / or active energy rays. It is preferable at the point which can make a big difference in solubility.
Here, the crosslinkable group refers to a group that reacts with the same or different groups of other molecules located nearby by irradiation with heat and / or active energy rays to form a new chemical bond.
Examples of the crosslinkable group include groups shown in the crosslinkable group group T in that it is easily insolubilized.

  [Crosslinkable group T]

(In formula, R < ¹ > -R < ⁵ > represents a hydrogen atom or an alkyl group each independently. Ar < ³¹ > may have the aromatic hydrocarbon group or substituent which may have a substituent. Represents an aromatic heterocyclic group.)
Groups that are insolubilized by cationic polymerization, such as cyclic ether groups such as epoxy groups and oxetane groups, and vinyl ether groups are preferred because they are highly reactive and easily insolubilized. Among these, an oxetane group is particularly preferable from the viewpoint that the rate of cationic polymerization can be easily controlled, and a vinyl ether group is preferable from the viewpoint that a hydroxyl group that may cause deterioration of the device during the cationic polymerization is hardly generated.

A group that undergoes a cycloaddition reaction, such as an arylvinylcarbonyl group such as a cinnamoyl group, or a group derived from a benzocyclobutene ring, is preferred from the viewpoint of further improving electrochemical stability.
Among the crosslinkable groups, a group derived from a benzocyclobutene ring is particularly preferable in that the structure after insolubilization is particularly stable.
The crosslinkable group may be directly bonded to the aromatic hydrocarbon group or aromatic heterocyclic group in the molecule, but may be bonded via a divalent group. As the divalent group, a group selected from an —O— group, a —C (═O) — group, or an (optionally substituted) —CH ₂ — group may be selected from 1 to 30 in any order. It is preferable to bind to an aromatic hydrocarbon group or an aromatic heterocyclic group via a divalent group formed by connecting them individually.

(Leaving group)
The hole transport material according to the present invention preferably has a leaving group as an insolubilizing group in terms of excellent charge transporting ability after insolubilization (after dissociation reaction).
Here, the leaving group refers to a group that dissociates from a bonded aromatic hydrocarbon ring at 70 ° C. or more and is soluble in a solvent. Here, being soluble in a solvent means that the compound is dissolved in toluene at 0.1% by weight or more at room temperature in a state before reacting by irradiation with heat and / or active energy rays. The solubility in toluene is preferably 0.5% by weight or more, more preferably 1% by weight or more.

Such a leaving group is preferably a group that is thermally dissociated without forming a polar group on the aromatic hydrocarbon ring side, and more preferably a group that is thermally dissociated by a reverse Diels-Alder reaction.
Furthermore, it is preferably a group that thermally dissociates at 100 ° C. or higher, and preferably a group that thermally dissociates at 300 ° C. or lower.

Specific examples of the leaving group are as follows, but the present invention is not limited thereto.
Specific examples in the case where the leaving group is a divalent group are as shown in <Divalent leaving group group A> below.
<Divalent leaving group A>

Specific examples in the case where the leaving group is a monovalent group are as shown in <Monovalent leaving group group B> below.
<Monovalent leaving group B>

The compound having an insolubilizing group may be any of a monomer, an oligomer and a polymer, but is preferably a polymer in terms of excellent film formability. Compounds having an insolubilizing group may be used alone, or two or more may be used in any combination and in any ratio.
Examples of the compound having an insolubilizing group, it is preferable to use a hole-transporting compound having insolubilizing groups. Examples of the hole transporting compound include those exemplified above, and those in which an insolubilizing group is bonded to the main chain or side chain with respect to these hole transporting compounds. In particular, the insolubilizing group is preferably bonded to the main chain via a linking group such as an alkylene group. In particular, the hole transporting compound is preferably a polymer compound containing a repeating unit having an insolubilizing group, and the insolubilizing group is represented by the above formula (II) or formulas (III-1) to (III-3). A polymer compound having a repeating unit bonded directly or via a linking group is preferred.

When forming the hole transport layer 4 by a wet film formation method, in the same manner as the formation of the hole injection layer 3,
After preparing the composition for forming a hole transport layer, it is heated and dried after wet film formation.
The composition for forming a hole transport layer contains a solvent in addition to the above hole transport compound. The solvent used is the same as that used for the composition for forming a hole injection layer. The film forming conditions, heat drying conditions, and the like are the same as in the case of forming the hole injection layer 3.

In the case where the hole transport layer is formed by the vacuum deposition method, the film forming conditions are the same as those in the case of forming the hole injection layer 3.
The hole transport layer 4 may contain various light emitting materials, electron transport compounds, binder resins, coating property improving agents, and the like in addition to the hole transport compound.
The hole transport layer 4 may also be a layer formed by crosslinking a crosslinkable compound. The crosslinkable compound is a compound having a crosslinkable group, and forms a network polymer compound by crosslinking.

Examples of this crosslinkable group include groups derived from cyclic ethers such as oxetane and epoxy; groups derived from unsaturated double bonds such as vinyl, trifluorovinyl, styryl, acrylic, methacryloyl and cinnamoyl; benzo Examples include groups derived from cyclobutene.
The crosslinkable compound may be any of a monomer, an oligomer, and a polymer. The crosslinkable compound may have only 1 type, and may have 2 or more types by arbitrary combinations and ratios.

  As the crosslinkable compound, a hole transporting compound having a crosslinkable group is preferably used. Examples of the hole transporting compound include those exemplified above, and those having a crosslinkable group bonded to the main chain or side chain with respect to these hole transporting compounds. In particular, the crosslinkable group is preferably bonded to the main chain via a linking group such as an alkylene group. In particular, the hole transporting compound is preferably a polymer containing a repeating unit having a crosslinkable group, and the above formula (II) and formulas (III-1) to (III-3) can be used as a crosslinkable group. Is preferably a polymer having a repeating unit bonded directly or via a linking group.

In order to form a hole transport layer 4 by crosslinking a crosslinkable compound, a composition for forming a hole transport layer in which a crosslinkable compound is dissolved or dispersed in a solvent is usually prepared and deposited by wet film formation. To crosslink.
The composition for forming a hole transport layer may contain an additive for promoting a crosslinking reaction in addition to the crosslinking compound. Examples of additives that promote the crosslinking reaction include polymerization initiators and polymerization accelerators such as alkylphenone compounds, acylphosphine oxide compounds, metallocene compounds, oxime ester compounds, azo compounds, onium salts; condensed polycyclic hydrocarbons, And photosensitizers such as porphyrin compounds and diaryl ketone compounds.

Further, it may contain a coating property improving agent such as a leveling agent and an antifoaming agent; an electron accepting compound; a binder resin;
In the composition for forming a hole transport layer, the crosslinkable compound is usually 0.01% by weight or more, preferably 0.05% by weight or more, more preferably 0.1% by weight or more, usually 50% by weight or less, preferably 20%. It is contained in an amount of not more than wt%, more preferably not more than 10 wt%.

After forming a composition for forming a hole transport layer containing a crosslinkable compound at such a concentration on the lower layer (usually the hole injection layer 3), the composition is crosslinked by heating and / or irradiation with electromagnetic energy such as light. Are crosslinked to form a network polymer compound.
Conditions such as temperature and humidity during film formation are the same as those during the wet film formation of the hole injection layer 3.
The heating method after film formation is not particularly limited. As heating temperature conditions, it is 120 degreeC or more normally, Preferably it is 400 degrees C or less.

The heating time is usually 1 minute or longer, preferably 24 hours or shorter. The heating means is not particularly limited, and means such as placing a laminated body having a deposited layer on a hot plate or heating in an oven is used. For example, conditions such as heating on a hot plate at 120 ° C. or more for 1 minute or more can be used.
In the case of irradiation with electromagnetic energy such as light, a method of irradiating directly using an ultraviolet / visible / infrared light source such as an ultra-high pressure mercury lamp, a high-pressure mercury lamp, a halogen lamp or an infrared lamp, or the above-mentioned light source is incorporated. Examples include a mask aligner and a method of irradiation using a conveyor type light irradiation device. In electromagnetic energy irradiation other than light, for example, there is a method of irradiation using a device that irradiates a microwave generated by a magnetron, a so-called microwave oven. As the irradiation time, it is preferable to set conditions necessary for reducing the solubility of the film, but irradiation is usually performed for 0.1 seconds or longer, preferably 10 hours or shorter.

Irradiation of electromagnetic energy such as heating and light may be performed individually or in combination. When combined, the order of implementation is not particularly limited.
The film thickness of the hole transport layer 4 thus formed is usually 5 nm or more, preferably 10 nm or more, and usually 300 nm or less, preferably 100 nm or less.

{Light emitting layer}
The light emitting layer is formed on the hole transport layer when the hole transport layer is present, and on the hole injection layer when there is no hole transport layer.
Regarding the light emitting layer, the material and the film forming method are the same as the material and the film forming method described in the above section [Low molecular compound]. The same applies to preferred specific examples and conditions.
That is, the organic electroluminescent device of the present invention has a layer formed by wet coating using an ink jet method or a nozzle printing method using the composition for organic electroluminescent device prepared by the above-described manufacturing method. In addition, the layer is preferably a light emitting layer.

{Hole blocking layer}
A hole blocking layer 6 may be provided between the light emitting layer 5 and an electron injection layer 8 described later. The hole blocking layer 6 is a layer laminated on the light emitting layer 5 so as to be in contact with the interface of the light emitting layer 5 on the cathode 9 side.
The hole blocking layer 6 has a role of blocking holes moving from the anode 2 from reaching the cathode 9 and a role of efficiently transporting electrons injected from the cathode 9 toward the light emitting layer 5. Have

  The physical properties required for the material constituting the hole blocking layer 6 include high electron mobility, low hole mobility, a large energy gap (difference between HOMO and LUMO), and excited triplet level (T1). Is high. Examples of the material for the hole blocking layer satisfying such conditions include bis (2-methyl-8-quinolinolato) (phenolato) aluminum, bis (2-methyl-8-quinolinolato) (triphenylsilanolato) aluminum, and the like. Mixed metal complexes such as bis (2-methyl-8-quinolato) aluminum-μ-oxo-bis- (2-methyl-8-quinolinato) aluminum binuclear metal complexes, distyrylbiphenyl derivatives, etc. Triazole derivatives such as styryl compounds (JP-A-11-242996), 3- (4-biphenylyl) -4-phenyl-5 (4-tert-butylphenyl) -1,2,4-triazole (JP-A-7 -41759), phenanthroline derivatives such as bathocuproine (JP-A-10-79297), and the like. That. Further, a compound having at least one pyridine ring substituted at positions 2, 4, and 6 described in International Publication No. 2005-022962 is also preferable as a material for the hole blocking layer 6.

In addition, the material of the hole-blocking layer 6 may use only 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.
There is no restriction | limiting in the formation method of the hole-blocking layer 6. FIG. Therefore, it can be formed by a wet film forming method, a vapor deposition method, or other methods.
The thickness of the hole blocking layer 6 is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.3 nm or more, preferably 0.5 nm or more, and usually 100 nm or less, preferably 50 nm or less.

{Electron transport layer}
An electron transport layer 7 may be provided between the light emitting layer 5 and an electron injection layer 8 described later.
The electron transport layer 7 is provided for the purpose of further improving the light emission efficiency of the device, and efficiently transports electrons injected from the cathode 9 between the electrodes to which an electric field is applied in the direction of the light emitting layer 5. Formed from a compound capable of
As an electron transporting compound used for the electron transport layer 7, usually, the electron injection efficiency from the cathode 9 or the electron injection layer 8 is high, and the injected electrons having high electron mobility are efficiently transported. The compound which can be used is used. Examples of the compound satisfying such conditions include metal complexes such as aluminum complexes of 8-hydroxyquinoline (Japanese Patent Laid-Open No. 59-194393), metal complexes of 10-hydroxybenzo [h] quinoline, and oxadiazole derivatives. , Distyrylbiphenyl derivatives, silole derivatives, 3-hydroxyflavone metal complexes, 5-hydroxyflavone metal complexes, benzoxazole metal complexes, benzothiazole metal complexes, trisbenzimidazolylbenzene (US Pat. No. 5,645,948), quinoxaline compounds ( JP-A-6-207169), phenanthroline derivative (JP-A-5-331459), 2-t-butyl-9,10-N, N'-dicyanoanthraquinonediimine, n-type hydrogenated amorphous silicon carbide , N-type zinc sulfide, n-type Sele Zinc oxide and the like.

In addition, the material of the electron carrying layer 7 may use only 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.
There is no restriction | limiting in the formation method of the electron carrying layer 7. FIG. Therefore, it can be formed by a wet film forming method, a vapor deposition method, or other methods.
The thickness of the electron transport layer 7 is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 1 nm or more, preferably 5 nm or more, and usually 300 nm or less, preferably 100 nm or less.

{Electron injection layer}
The electron injection layer 8 plays a role of efficiently injecting electrons injected from the cathode 9 into the light emitting layer 5. In order to perform electron injection efficiently, the material for forming the electron injection layer 8 is preferably a metal having a low work function. Examples include alkali metals such as sodium and cesium, alkaline earth metals such as barium and calcium, and the film thickness is preferably from 0.1 nm to 5 nm.
Furthermore, an organic electron transport compound represented by a metal complex such as a nitrogen-containing heterocyclic compound such as bathophenanthroline or an aluminum complex of 8-hydroxyquinoline is doped with an alkali metal such as sodium, potassium, cesium, lithium, or rubidium ( (As described in JP-A-10-270171, JP-A-2002-1000047, JP-A-2002-1000048, etc.), it is possible to improve the electron injection / transport properties and achieve excellent film quality. preferable. In this case, the film thickness is usually 5 nm or more, preferably 10 nm or more, and is usually 200 nm or less, preferably 100 nm or less.

In addition, the material of the electron injection layer 8 may use only 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.
There is no restriction | limiting in the formation method of the electron injection layer 8. FIG. Therefore, it can be formed by a wet film forming method, a vapor deposition method, or other methods.

{cathode}
The cathode 9 plays a role of injecting electrons into a layer on the light emitting layer 5 side (such as the electron injection layer 8 or the light emitting layer 5).
As the material of the cathode 9, the material used for the anode 2 can be used. However, in order to perform electron injection efficiently, a metal having a low work function is preferable. For example, tin, magnesium, indium, A suitable metal such as calcium, aluminum, silver, or an alloy thereof is used. Specific examples include low work function alloy electrodes such as magnesium-silver alloy, magnesium-indium alloy, and aluminum-lithium alloy.

In addition, the material of the cathode 9 may use only 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.
The film thickness of the cathode 9 is usually the same as that of the anode 2.
Further, for the purpose of protecting the cathode 9 made of a low work function metal, it is preferable to further stack a metal layer having a high work function and stable to the atmosphere because the stability of the device is increased. For this purpose, for example, metals such as aluminum, silver, copper, nickel, chromium, gold and platinum are used. In addition, these materials may be used only by 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

{Other layers}
The organic electroluminescent element according to the present invention may have another configuration without departing from the gist thereof. For example, as long as the performance is not impaired, an arbitrary layer may be provided between the anode 2 and the cathode 9 in addition to the layers described above, and an arbitrary layer may be omitted. .

<Electron blocking layer>
Examples of the layer that may be included include an electron blocking layer.
The electron blocking layer is provided between the hole injection layer 3 or the hole transport layer 4 and the light emitting layer 5 and prevents electrons moving from the light emitting layer 5 from reaching the hole injection layer 3. Thus, the probability of recombination of holes and electrons in the light emitting layer 5 is increased, the excitons generated are confined in the light emitting layer 5, and the holes injected from the hole injection layer 3 are efficiently collected. There is a role to transport in the direction of. In particular, when a phosphorescent material or a blue light emitting material is used as the light emitting material, it is effective to provide an electron blocking layer.

  The characteristics required for the electron blocking layer include high hole transportability, a large energy gap (difference between HOMO and LUMO), and a high excited triplet level (T1). Furthermore, in the present invention, when the light emitting layer 5 is formed as an organic layer according to the present invention by a wet film formation method, the electron blocking layer is also required to be compatible with the wet film formation. Examples of the material used for such an electron blocking layer include a copolymer of dioctylfluorene and triphenylamine typified by F8-TFB (International Publication No. 2004/084260).

In addition, the material of an electron blocking layer may use only 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.
There is no restriction | limiting in the formation method of an electron blocking layer. Therefore, it can be formed by a wet film forming method, a vapor deposition method, or other methods.

Further, at the interface between the cathode 9 and the light emitting layer 5 or the electron transport layer 7, for example, lithium fluoride (LiF), magnesium fluoride (MgF ₂ ), lithium oxide (Li ₂ O), cesium carbonate (II) (CsCO ₃ ). Inserting an ultrathin insulating film (0.1 to 5 nm) formed by the above method is also an effective method for improving the efficiency of the device (Applied Physics Letters, 1997, Vol. 70, pp. 152; (Kaihei 10-74586; IEEE Transactions on Electron Devices, 1997, Vol. 44, pp. 1245; SID 04 Digest, pp. 154, etc.).

Moreover, in the layer structure demonstrated above, it is also possible to laminate | stack components other than a board | substrate in reverse order. For example, in the case of the layer configuration of FIG. 1, the other components on the substrate 1 are the cathode 9, the electron injection layer 8, the electron transport layer 7, the hole blocking layer 6, the light emitting layer 5, the hole transport layer 4, The hole injection layer 3 and the anode 2 may be provided in this order.
Furthermore, it is also possible to constitute the organic electroluminescent element according to the present invention by laminating components other than the substrate between two substrates, at least one of which is transparent.

In addition, a structure in which a plurality of components (light emitting units) other than the substrate are stacked in a plurality of layers (a structure in which a plurality of light emitting units are stacked) may be employed. In that case, instead of the interface layer between the steps (between the light emitting units) (when the anode is ITO and the cathode is Al, these two layers), for example, a charge made of vanadium pentoxide (V ₂ O ₅ ) or the like. When a generation layer (Carrier Generation Layer: CGL) is provided, a barrier between steps is reduced, which is more preferable from the viewpoint of light emission efficiency and driving voltage.

Furthermore, the organic electroluminescent device according to the present invention may be configured as a single organic electroluminescent device, or may be applied to a configuration in which a plurality of organic electroluminescent devices are arranged in an array. You may apply to the structure by which the cathode is arrange | positioned at XY matrix form.
Each layer described above may contain components other than those described as materials unless the effects of the present invention are significantly impaired.

<Organic EL display and organic EL lighting>
The organic EL display and the organic EL illumination of the present invention use the organic electroluminescent element of the present invention as described above. There is no restriction | limiting in particular about the type and structure of the organic electroluminescent display of this invention, and organic electroluminescent illumination, It can assemble in accordance with a conventional method using the organic electroluminescent element of this invention.
For example, the organic EL display and the organic EL display of the present invention can be obtained by the method described in “Organic EL display” (Ohm, August 20, 2004, published by Shizushi Tokito, Chiba Adachi, Hideyuki Murata). EL illumination can be formed.

EXAMPLES Next, although an Example demonstrates this invention further more concretely, this invention is not limited to description of a following example, unless the summary is exceeded.
Example 1
The organic electroluminescent element shown in FIG. 1 was produced.
An indium tin oxide (ITO) transparent conductive film deposited on a glass substrate 1 with a thickness of 120 nm (manufactured by Sanyo Vacuum Co., Ltd., sputtered film product) using ordinary photolithography technology and hydrochloric acid etching Then, the anode 2 was formed by patterning into stripes having a width of 2 mm. The patterned ITO substrate is cleaned in the order of ultrasonic cleaning with an aqueous surfactant solution, water cleaning with ultrapure water, ultrasonic cleaning with ultrapure water, and water cleaning with ultrapure water, followed by drying with compressed air, and finally UV irradiation. Ozone cleaning was performed.

First, 2% by weight of a hole transporting polymer having a repeating structure represented by the following structural formula (P1) and 4-isopropyl-4′-methyldiphenyliodonium tetrakis (pentafluorophenyl) borate represented by the following structural formula (B1) After 0.8% by weight was dissolved in ethyl benzoate as a solvent, it was filtered using a PTFE (polytetrafluoroethylene) membrane filter having a pore size of 0.2 μm to prepare a coating composition. This coating composition was spin-coated on the glass substrate. The spin coating was performed in an air atmosphere at a temperature of 23 ° C. and a relative humidity of 58%, the spinner rotation speed was 1500 rpm, and the spinner time was 30 seconds. After spin coating, it was heated and dried on a hot plate at 80 ° C. for 1 minute, and then heated in an oven at 230 ° C. for 180 minutes in an atmospheric atmosphere. In this way, a hole injection layer 3 having a thickness of 30 nm was formed.

  Next, 0.4% by weight of a hole transporting polymer having a repeating structure represented by the following structural formula (P2) is dissolved in toluene as a solvent in a nitrogen atmosphere glove box, and then the pore diameter is 0.2 μm. It filtered using the membrane filter made from PTFE (polytetrafluoroethylene), and produced the coating composition. This coating composition was spin-coated on the previous hole injection layer 3. Spin coating was performed in a nitrogen atmosphere glove box, the spinner rotation speed was 1500 rpm, and the spinner time was 30 seconds. After spin coating, heating was performed at 130 ° C. for 60 minutes on a hot plate in a nitrogen glove box to form a 20 nm-thick hole transport layer 4.

  Next, 25 mg of a low molecular compound represented by the following structural formula (C1), 25 mg of a compound represented by the following structural formula (C2), and 2.5 mg of a compound represented by the following structural formula (C3) Then, 1 ml of cyclohexylbenzene as a solvent was added in a nitrogen atmosphere glove box, stirred gently, and then subjected to a heat treatment at 130 ° C. for 1 hour on a hot plate in the nitrogen atmosphere glove box. The organic electroluminescent element composition of the present invention was applied on the hole transport layer 4 to a thickness of 60 nm by spin coating to form the light emitting layer 5. The spin coating was performed in a nitrogen atmosphere glove box, the spinner rotation speed was 1500 rpm, and the spinner time was 120 seconds. Thereafter, the chamber was depressurized to a vacuum degree of 0.01 MPa on a hot plate in a chamber capable of depressurizing the inside, and dried by heating at 130 ° C. for 1 hour.

Next, after fixing the substrate on which the hole injection layer 3, the hole transport layer 4 and the light emitting layer 5 are coated and fixed to a substrate holder of a commercially available vacuum deposition apparatus, and performing rough evacuation of the apparatus with an oil rotary pump, It exhausted using the cryopump until the vacuum degree in an apparatus was set to 4.3x10 <^-4> Pa, and the compound represented by the following structural formula (C4) was laminated | stacked by the vacuum evaporation method. The degree of vacuum during deposition is 2.1 × 10 ^{−5 to} 3.6 × 10 ⁻⁵ Pa, the deposition rate is controlled in the range of 0.8 to 1.2 liters / second, and a film with a thickness of 5 nm is formed on the light emitting layer. The hole blocking layer 6 was formed by laminating on the top.

Next, deposition was performed by heating tris (8-hydroxyquinolinato) aluminum placed in a ceramic crucible disposed in the apparatus. The degree of vacuum during deposition is 2.7 × 10 ^{−5 to} 3.4 × 10 ⁻⁵ Pa, the deposition rate is controlled within the range of 0.8 to 1.2 liters / second, and a hole with a thickness of 30 nm is blocked. The electron transport layer 7 was formed by laminating on the layer 5.

Here, the element on which the electron transport layer 7 has been evaporated is taken out of the vapor deposition apparatus, and a 2 mm wide stripe shadow mask as a cathode vapor deposition mask is adhered to the element so as to be orthogonal to the ITO stripe of the anode 2. Then, it was installed in another vacuum vapor deposition apparatus and evacuated until the degree of vacuum in the apparatus was 6.3 × 10 ⁻⁵ Pa or less in the same manner as in the organic layer vapor deposition.
Lithium fluoride (LiF) is used as the electron injection layer 8 by using a molybdenum boat, a deposition rate of 0.09 to 0.15 liters / second, and a degree of vacuum of 4.1 × 10 ^{−5 to} 7.8 × 10 ⁻⁵ Pa. The film was formed on the electron transport layer with a film thickness of 0.5 nm. Next, aluminum was similarly heated by a molybdenum boat, and the deposition rate was controlled to 0.6 to 7.0 liters / second and the degree of vacuum 2.4 × 10 ^{−5 to} 12 × 10 ⁻⁵ Pa, and the film thickness was 80 nm. The aluminum layer was formed to form the cathode 9. The substrate temperature at the time of vapor deposition of the electron injection layer and the cathode was kept at room temperature.

Subsequently, in order to prevent the element from being deteriorated by moisture in the atmosphere during storage, a sealing process was performed by the method described below. In a nitrogen glove box, a photocurable resin 30Y-437 (manufactured by Three Bond) is applied to the outer periphery of a 23 mm × 23 mm size glass plate with a width of about 1 mm, and a moisture getter sheet (manufactured by Dynic) is applied to the center. Was installed. On this, the board | substrate which complete | finished cathode formation was bonded together so that the vapor-deposited surface might oppose a desiccant sheet. Then, only the area | region where the photocurable resin was apply | coated was irradiated with ultraviolet light, and resin was hardened. As described above, an organic electroluminescent element having a light emitting area portion having a size of 2 mm × 2 mm was obtained.

Table 1 shows the results of a life test when the obtained organic electroluminescent element was driven at a constant current at a current density with an initial luminance of 4,000 cd / m ² by a DC voltage. LT80 means the time until the luminance is reduced to 80% of the initial luminance.
As shown in Table 1, it can be seen that the organic electroluminescence device produced by the method for producing an organic electroluminescence device of the present invention has a short driving life (Comparative Example 1).
When preparing a low-molecular composition for forming the light-emitting layer 5, 1 ml of cyclohexylbenzene as a solvent is added to a vial bottle in which low-molecular compounds C1, C2, and C3 are separated, and then stirred without performing heat treatment. Table 1 shows the results of producing an organic electroluminescent element in the same manner as in Example 1 and conducting a driving life test in the same manner as in Example 1.

Claims (5)

A method for producing a composition for an organic electroluminescent device comprising a light-emitting low molecular weight compound and a solvent,
A mixture of a light-emitting low-molecular compound and a solvent,
The manufacturing method of the composition for organic electroluminescent elements characterized by including the process heated at 100 degreeC or more and 10 degreeC or more lower than the boiling point of the solvent with the lowest boiling point contained in this mixture.   The method for producing a composition for an organic electroluminescent element according to claim 1, wherein in the heating step, the heating time is 5 minutes or more.   The method for producing a composition for an organic electroluminescent element according to claim 1, wherein after completion of the heating step, a solvent having a boiling point satisfying a boiling point ≦ (maximum heating temperature + 10 ° C.) is mixed. . A method for producing an organic electroluminescent element, comprising performing wet film formation using the composition produced by the production method according to claim 3 . A method for producing an organic electroluminescent element, wherein the composition produced by the production method according to claim 3 is wet-coated by an ink jet method or a nozzle print method.

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