WO2011114833A1

WO2011114833A1 - Method for producing organic electroluminescence element

Info

Publication number: WO2011114833A1
Application number: PCT/JP2011/053425
Authority: WO
Inventors: 直之林; 郁雄木下; 隆志加藤; 浩二高久
Original assignee: 富士フイルム株式会社
Priority date: 2010-03-15
Filing date: 2011-02-17
Publication date: 2011-09-22
Also published as: JP2011216455A; TW201241148A; JP5567407B2

Abstract

Provided is a method for producing an organic electroluminescence element, said organic electroluminescence element having an organic layer which contains a light-emitting layer between an anode and a cathode. The method for producing the organic electroluminescence element involves forming the light-emitting layer by applying a coating solution in which a light-emitting material, and a host material, which is represented by general formula (1) and/or general formula (2) below, have been dissolved or dispersed in a solvent, and heating the coating solution at a temperature higher than the glass transition temperature of the host material, and higher than the boiling point of the solvent.

Description

Method for manufacturing organic electroluminescent device

The present invention relates to a method for manufacturing an organic electroluminescent element.

Organic electroluminescence devices have features such as self-emission and high-speed response, and are expected to be applied to flat panel displays. In particular, organic thin films (hole transport layer) that have a hole transport property and organic materials that have an electron transport property. Since a two-layer type (laminated type) in which a thin film (electron transport layer) is laminated is reported, it has attracted attention as a large-area light-emitting element that emits light at a low voltage of 10 V or less. The stacked organic electroluminescent element has a basic configuration of positive electrode / hole transport layer / light emitting layer / electron transport layer / negative electrode.

In such an organic electroluminescent device, in order to achieve homogenization of the film, for example, a dicarbazole derivative (CBP) is used as a host material, toluene is used as a solvent, and the glass transition temperature of the light emitting layer is −30 ° C. A method of performing heat treatment by the backside heat transfer method at a temperature not exceeding the decomposition temperature of the organic compound constituting the light emitting layer (see Patent Document 1), and a functional ink when the organic light emitting medium layer is dried There has been proposed a method of heating above the boiling point of the organic solvent that constitutes and heating around the glass transition temperature (Tg) (see Patent Document 2).
However, although these methods can realize the homogenization of the film, the organic electroluminescence device manufactured by these methods has a problem that the rate of change in luminance attenuation immediately after the start of driving is large.
Further, in order to realize a long lifetime, for example, there is a method in which a light emitting layer composition containing a host compound, a dopant compound and a solvent is heat-treated at a temperature higher than the glass transition temperature of the host compound and higher than the boiling point of the solvent. It has been proposed (see Patent Document 3).
However, the organic electroluminescent device manufactured by this method has a problem that the rate of change in luminance attenuation immediately after the start of driving is large.

Therefore, at present, there is a strong demand for rapid development of a method for manufacturing an organic electroluminescent element having a small rate of change in luminance attenuation immediately after the start of driving.

JP 2009-163889 A JP 2009-129567 A JP 2009-164033 A

An object of the present invention is to provide a method for manufacturing an organic electroluminescent element having a small change rate of luminance attenuation immediately after the start of driving.

Means for solving the problems are as follows. That is,
<1> A method for producing an organic electroluminescent device comprising an organic layer including a light emitting layer between an anode and a cathode,
The light emitting layer is coated with a coating solution prepared by dissolving or dispersing a light emitting material and a host material represented by at least one of the following general formula (1) and the following general formula (2) in a solvent, It is formed by heating at a temperature higher than the glass transition temperature and higher than the boiling point of the solvent.

In the general formula (1), R represents any one of t-butyl group, t-amyl group, trimethylsilyl group, triphenylsilyl group and phenyl group, and R ₁ to R ₂₃ each represents a hydrogen atom. , T-butyl group, t-amyl group, trimethylsilyl group, triphenylsilyl group, phenyl group, cyano group and alkyl group having 1 to 5 carbon atoms.

However, in said general formula (2), R represents arbitrary substituents.
<2> The method for producing an organic electroluminescent element according to <1>, wherein the molecular weight of the light emitting material is 1,500 or less, and the molecular weight of the host material is 1,500 or less.
<3> Any of <1> to <2>, wherein the host material represented by the general formula (1) is a compound represented by any one of the following structural formulas (1) to (6) and (11) It is a manufacturing method of the organic electroluminescent element as described in above.

<4> The organic electroluminescent element according to any one of <1> to <3>, wherein the host material represented by the general formula (2) is a compound represented by any one of the following structural formulas C and E: It is a manufacturing method.

<5> The organic electroluminescent element according to any one of <1> to <4>, wherein the solvent is at least one selected from 2-butanone, xylene, toluene, 2-methyltetrahydrofuran, and methyl isobutyl ketone. It is a manufacturing method.
<6> The organic electroluminescence according to any one of <1> to <5>, wherein the luminescent material is a compound represented by any one of the following structural formulas (7), (8), (12) and D: It is a manufacturing method of an element.

<7> The organic electroluminescence device according to any one of <1> to <6>, wherein the heating temperature is 10 ° C. or more higher than the glass transition temperature of the host material and 45 ° C. or more higher than the boiling point of the solvent. It is a manufacturing method.

According to the present invention, it is possible to provide a method for manufacturing an organic electroluminescent element that can solve the above-described problems and achieve the above-described object and has a small change rate of luminance attenuation immediately after the start of driving.

FIG. 1 is a schematic view showing an example of the layer structure of the organic electroluminescent element of the present invention. FIG. 2 is a graph showing an example of a change in luminance attenuation immediately after the start of driving of the organic electroluminescent element manufactured by the method of manufacturing an organic electroluminescent element of the present invention.

(Method for manufacturing organic electroluminescent device)
The manufacturing method of the organic electroluminescent element of the present invention includes at least a light emitting layer forming step, and further includes other steps appropriately selected as necessary.

<Light emitting layer forming step>
The light emitting layer forming step is a step of applying a coating solution in which a light emitting material and a host material are dissolved or dispersed in a solvent, and heating to form a light emitting layer.

<< Luminescent Material >>
There is no restriction | limiting in particular as said luminescent material, Although it can select suitably according to the objective, The compound whose molecular weight is 1,500 or less is preferable.
The molecular weight of the light emitting material means the molecular weight of the compound having the highest molecular weight when the light emitting material is a mixture containing a plurality of compounds.

Generally, examples of the light emitting material include complexes containing transition metal atoms or lanthanoid atoms. Preferred examples of the transition metal atom include ruthenium, rhodium, palladium, tungsten, rhenium, osmium, iridium, and platinum. Among these, rhenium, iridium, and platinum are preferable, and iridium and platinum are more preferable.

Examples of the lanthanoid atom include lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium. Among these lanthanoid atoms, neodymium, europium, and gadolinium are preferable.
Examples of the ligand of the complex include G.I. Wilkinson et al., Comprehensive Coordination Chemistry, Pergamon Press, 1987, H.C. Listed by Yersin, “Photochemistry and Photophysics of Coordination Compounds”, published by Springer-Verlag, 1987, Akio Yamamoto, “Organic Metal Chemistry-Fundamentals and Applications,” published by Soukabo, 1982, etc. It is done.
The specific ligand is preferably a halogen ligand (preferably a chlorine ligand), an aromatic carbocyclic ligand (for example, a cyclopentadienyl anion, a benzene anion, or a naphthyl anion), Nitrogen-containing heterocyclic ligand (eg, phenylpyridine, benzoquinoline, quinolinol, bipyridyl, or phenanthroline), diketone ligand (eg, acetylacetone), carboxylic acid ligand (eg, acetic acid ligand) , Alcoholate ligands (eg, phenolate ligands), carbon monoxide ligands, isonitrile ligands, and cyano ligands, more preferably nitrogen-containing heterocyclic ligands.

The complex may have one transition metal atom in the compound, or may be a so-called binuclear complex having two or more. Different metal atoms may be contained at the same time.
Specific examples of the light emitting material containing platinum include, but are not limited to, the following.

The light emitting material containing iridium is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include compounds represented by the following structural formulas.

-Host material-
The host material is not particularly limited as long as it is represented by at least one of the following general formula (1) and the following general formula (2), but a compound having a molecular weight of 1,500 or less is preferable.

In the general formula (1), R represents any one of a t-butyl group, a t-amyl group, a trimethylsilyl group, a triphenylsilyl group, and a phenyl group, and R ₁ to R ₂₃ are a hydrogen atom, t -Represents any one of a butyl group, a t-amyl group, a trimethylsilyl group, a triphenylsilyl group, a phenyl group, a cyano group, and an alkyl group having 1 to 5 carbon atoms.

In the general formula (2), R represents an arbitrary substituent. R is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a methyl group and a phenyl group.

The molecular weight of the host material means the molecular weight of the compound having the largest molecular weight when the host material is a mixture containing a plurality of compounds.

The compound represented by the general formula (1) is not particularly limited and may be appropriately selected depending on the intended purpose. For example, the compound represented by any one of the following structural formulas (1) to (19) Etc.

There is no restriction | limiting in particular as a compound represented by the said General formula (2), According to the objective, it can select suitably, For example, the compound etc. which are represented by either of the following structural formula C and E are mentioned. .

The glass transition temperature Tg of the host material means a temperature at which the supercooled liquid transitions to the glass state, and can be measured as follows.

<Measuring method of glass transition temperature Tg>
The glass transition temperature Tg can be measured for the temperature of the endothermic peak by differential thermal analysis (DTA).
The glass transition temperature Tg of the host material means the glass transition temperature Tg of the compound having the highest glass transition temperature Tg when the host material is a mixture containing a plurality of compounds.

-solvent-
The solvent is not particularly limited and may be appropriately selected depending on the intended purpose. For example, 2-butanone, methyl isobutyl ketone as the ketone solvent, xylene, toluene, cumene, trimethylbenzene as the aromatic solvent Examples of ether solvents include tetrahydrofuran and 2-methyltetrahydrofuran. These may be used individually by 1 type and may use 2 or more types together.
Among these, xylene, toluene, 2-butanone, and methyl isobutyl ketone are preferable from the viewpoint of ease of film formation.

The boiling point of the solvent means the boiling point of the solvent having the highest boiling point when the solvent is a mixed solvent containing a plurality of solvents.

The content of the solid content (the host material and the light emitting material) in the coating solution is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 0.001% by mass to 20% by mass. 0.01 mass% to 15 mass% is more preferable, and 0.1 mass% to 10 mass% is particularly preferable.
If the solid content is less than 0.001% by mass, the tact time is long, that is, the time required for coating may be long. If the content exceeds 20% by mass, clogging of the ink jet or spray may occur. May occur. On the other hand, when the content of the solid content is within the particularly preferable range, it is advantageous in that the tact time is short and the maintenance of the apparatus becomes unnecessary.
The mass ratio between the light emitting material and the host material is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 1:99 to 30:70, more preferably 2:98 to 20:80. A ratio of 4:96 to 15:75 is particularly preferable.
If the ratio of the light emitting material to the host material is less than 1 and more than 99, EL light emission may not be performed. If it is more than 30 and less than 70, EL light emission efficiency may be lowered due to concentration quenching. On the other hand, when the ratio of the light emitting material to the host material is within the particularly preferable range, it is advantageous in that the light emission efficiency is high.

<< Application >>
The application method is not particularly limited as long as the light emitting material and the host material can be applied with a coating solution in which the light emitting material and the host material are dissolved or dispersed in the solvent, and can be appropriately selected according to the purpose. Examples thereof include mist spraying such as coating, ink jet coating and spray coating.

<< Heating >>
The heating temperature in the heating is not particularly limited as long as it is higher than the glass transition temperature of the host material and higher than the boiling point of the solvent, and can be appropriately selected according to the purpose. However, the temperature is preferably 10 ° C. or higher than the glass transition temperature of the host material and 45 ° C. or higher than the boiling point of the solvent.
When the heating temperature is equal to or lower than the glass transition temperature of the host material, the orientation of the host material becomes random, and in the continuous driving of the organic electroluminescence device, the brightness may be drastically reduced at an early stage, If it is below the boiling point, it may remain in the organic solvent in the organic layer, and the durability and EL luminous efficiency of the organic electroluminescent device may be lowered. On the other hand, when the heating temperature is within the preferred range, it is advantageous in that the initial luminance drop in the continuous driving test is small.
When the host material is a mixture containing a plurality of compounds, the heating temperature needs to be higher than the glass transition temperature of each compound in the mixture, that is, the heating temperature is equal to the glass transition temperature of the compound in the mixture. Of these, it must be higher than the highest glass transition temperature.
When the solvent is a mixed solvent containing a plurality of solvents, the heating temperature needs to be higher than the boiling point of each solvent in the mixed solvent, that is, the heating temperature is the highest among the boiling points of the solvents in the mixed solvent. Must be higher than the high boiling point.

The heating time in the heating is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 1 minute to 5 hours, more preferably 5 minutes to 1 hour, and 5 minutes to 30 minutes. Is particularly preferred.
When the heating time is less than 1 minute, the solvent remains in the light emitting layer, the EL light emission efficiency and the durability of the organic electroluminescent element are lowered, the orientation of the host material cannot be changed, and the continuous driving test is performed. An initial luminance drop may occur, and if it exceeds 5 hours, decomposition due to oxidation or peeling of the film may occur. On the other hand, when the heating time is within the particularly preferable range, since there is no residual solvent, the efficiency of the organic electroluminescent element is high, the degree of orientation of the host material is high, and the initial luminance reduction of the continuous driving test is reduced. This is advantageous in that becomes smaller.

The number of times of heating is not particularly limited and may be appropriately selected depending on the purpose, and may be one or more times. In addition, when the frequency | count of the said heating is multiple times, heating temperature and heating time may be the same in each heating, or may differ.

<Hole injection layer forming step>
The hole injection layer forming step is a step of forming the hole injection layer.
The method for forming the hole injection layer is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a dry film forming method such as a vapor deposition method or a sputtering method, a wet coating method, a transfer method, or a printing method. , Inkjet method, and the like.

<Hole transport layer forming step>
The hole transport layer forming step is a step of forming the hole transport layer.
The method for forming the hole transport layer is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a dry film forming method such as a vapor deposition method or a sputtering method, a wet coating method, a transfer method, or a printing method. , Inkjet method, and the like.

<Other processes>
The other steps are not particularly limited and may be appropriately selected depending on the purpose. For example, an electron transport layer forming step, an electron injection layer forming step, a hole blocking layer forming step, an electron block layer forming step, Etc.

<Organic electroluminescent device>
The organic electroluminescent element has an organic layer between a pair of electrodes (anode and cathode), and may further have other layers appropriately selected as necessary.
The organic layer has at least a light emitting layer, and further includes a hole transport layer, an electron transport layer, a hole block layer, an electron block layer, a hole injection layer, an electron injection layer, and the like as necessary. May be.

<< Light emitting layer >>
The light-emitting layer contains the light-emitting material and the host material, and receives holes from the anode, hole injection layer, or hole transport layer when an electric field is applied, and receives the cathode, electron injection layer, or electron transport layer. It is a layer having a function of receiving electrons from and providing a field for recombination of holes and electrons to emit light.

The thickness of the light emitting layer is not particularly limited and may be appropriately selected according to the purpose. The thickness is preferably 2 nm to 500 nm, more preferably 3 nm to 200 nm, and particularly preferably 10 nm to 200 nm from the viewpoint of external quantum efficiency. Moreover, the said light emitting layer may be 1 layer, or may be two or more layers, and each layer may light-emit with a different luminescent color.

<< Hole injection layer, hole transport layer >>
The hole injection layer and the hole transport layer are layers having a function of receiving holes from the anode or the anode side and transporting them to the cathode side. The hole injection layer and the hole transport layer may have a single layer structure or a multilayer structure composed of a plurality of layers having the same composition or different compositions.

-Hole injection material, hole transport material-
The hole injection material or hole transport material used for the hole injection layer and the hole transport layer may be a low molecular compound or a high molecular compound.
The hole injection material or hole transport material is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include pyrrole derivatives, carbazole derivatives, triazole derivatives, oxazole derivatives, oxadiazole derivatives, imidazoles. Derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aromatic tertiary amine compounds, Examples include styrylamine compounds, aromatic dimethylidin compounds, phthalocyanine compounds, porphyrin compounds, thiophene derivatives, organic silane derivatives, and carbon. These may be used individually by 1 type and may use 2 or more types together.

The hole injection layer and the hole transport layer may contain an electron accepting dopant.
As the electron-accepting dopant, an inorganic compound or an organic compound can be used as long as it has an electron-accepting property and oxidizes an organic compound.
The inorganic compound is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include metal halides such as ferric chloride, aluminum chloride, gallium chloride, indium chloride and antimony pentachloride; vanadium pentoxide And metal oxides such as molybdenum trioxide.
The organic compound is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a compound having a nitro group, a halogen, a cyano group, a trifluoromethyl group or the like as a substituent; a quinone compound, an acid anhydride And physical compounds, fullerenes, and the like.
These electron-accepting dopants may be used alone or in combination of two or more.
The amount of the electron-accepting dopant used varies depending on the type of material, but is preferably 0.01% by mass to 50% by mass, and 0.05% by mass to 20% by mass with respect to the hole transport layer material or the hole injection material. % Is more preferable, and 0.1% by mass to 10% by mass is particularly preferable.

The thickness of the hole injection layer and the hole transport layer is preferably 1 nm to 500 nm, more preferably 5 nm to 200 nm, and particularly preferably 10 nm to 100 nm.

<< Electron transport layer, electron injection layer >>
The electron injection layer and the electron transport layer are layers having a function of receiving electrons from the cathode or the cathode side and transporting them to the anode side.

The electron injection layer and the electron transport layer preferably contain a reducing dopant.
The reducing dopant is not particularly limited and may be appropriately selected depending on the intended purpose. Examples of the reducing dopant include alkali metals, alkaline earth metals, rare earth metals, alkali metal oxides, alkali metal halides, alkaline earths. Selected from metal oxides, alkaline earth metal halides, rare earth metal oxides, rare earth metal halides, alkali metal organic complexes, alkaline earth metal organic complexes, and rare earth metal organic complexes It is preferable that there is at least one.
The amount of the reducing dopant used varies depending on the type of material, but is preferably 0.1% by mass to 99% by mass, more preferably 0.3% by mass to 80% by mass with respect to the electron transport layer material or the electron injection material. 0.5% by mass to 50% by mass is particularly preferable.

The electron transport layer and the electron injection layer can be formed according to a known method. For example, a vapor deposition method, a wet film forming method, an MBE (molecular beam epitaxy) method, a cluster ion beam method, a molecular stacking method, and an LB method. It can be suitably formed by a printing method, a transfer method, or the like.
The thickness of the electron transport layer is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 1 nm to 200 nm, more preferably 1 nm to 100 nm, and particularly preferably 1 nm to 50 nm.
The thickness of the electron injection layer is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 1 nm to 200 nm, more preferably 1 nm to 100 nm, and particularly preferably 1 nm to 50 nm.

<< Hole Block Layer, Electron Block Layer >>
The hole blocking layer is a layer having a function of preventing holes transported from the anode side to the light emitting layer from passing through to the cathode side, and is usually provided as an organic compound layer adjacent to the light emitting layer on the cathode side. .
The electron blocking layer is a layer having a function of preventing electrons transported from the cathode side to the light emitting layer from passing through to the anode side, and is usually provided as an organic compound layer adjacent to the light emitting layer on the anode side.
Examples of the compound constituting the hole blocking layer include aluminum complexes such as BAlq, triazole derivatives, phenanthroline derivatives such as BCP, and the like.
As examples of the compound constituting the electron blocking layer, for example, those mentioned as the hole transporting material can be used.

The electron block layer and the hole block layer are not particularly limited and can be formed according to a known method, for example, a dry film forming method such as a vapor deposition method and a sputtering method, a wet coating method, a transfer method, and a printing method. It can be suitably formed by an inkjet method or the like.
The thickness of the hole blocking layer and the electron blocking layer is preferably 1 nm to 200 nm, more preferably 1 nm to 50 nm, and particularly preferably 3 nm to 10 nm. In addition, the hole blocking layer and the electron blocking layer may have a single layer structure composed of one or more of the above-described materials, or may have a multilayer structure composed of a plurality of layers having the same composition or different compositions. .

<< Electrode >>
The organic electroluminescent element includes a pair of electrodes, that is, an anode and a cathode. In view of the nature of the organic electroluminescence device, at least one of the anode and the cathode is preferably transparent. Usually, the anode only needs to have a function as an electrode for supplying holes to the organic compound layer, and the cathode only needs to have a function as an electrode for injecting electrons into the organic compound layer.
There is no restriction | limiting in particular about the shape, a structure, a magnitude | size, etc. as said electrode, According to the use and objective of an organic electroluminescent element, it can select suitably from well-known electrode materials.
As a material which comprises the said electrode, a metal, an alloy, a metal oxide, a conductive compound, or a mixture thereof etc. are mentioned suitably, for example.

-anode-
Examples of the material constituting the anode include tin oxide doped with antimony and fluorine (ATO, FTO), tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), and indium zinc oxide (IZO). Conductive metal oxides; metals such as gold, silver, chromium and nickel; mixtures or laminates of these metals and conductive metal oxides; inorganic conductive materials such as copper iodide and copper sulfide; polyaniline, polythiophene, Examples thereof include organic conductive materials such as polypyrrole, and laminates of these with ITO. Among these, conductive metal oxides are preferable, and ITO is particularly preferable in terms of productivity, high conductivity, transparency, and the like.

-cathode-
Examples of the material constituting the cathode include alkali metals such as Li, Na, K, and Cs, alkaline earth metals such as Mg and Ca, gold, silver, lead, aluminum, sodium-potassium alloy, and lithium-aluminum alloy. , Magnesium-silver alloys, rare earth metals such as indium and ytterbium. These may be used alone, but two or more can be suitably used in combination from the viewpoint of achieving both stability and electron injection.
Among these, an alkali metal and an alkaline earth metal are preferable from the viewpoint of electron injection properties, and a material mainly composed of aluminum is preferable from the viewpoint of excellent storage stability.
The material mainly composed of aluminum is aluminum alone, an alloy of aluminum and 0.01% by mass to 10% by mass of alkali metal or alkaline earth metal, or a mixture thereof (for example, lithium-aluminum alloy, magnesium-aluminum). Alloy).

The method for forming the electrode is not particularly limited and can be performed according to a known method, for example, a wet method such as a printing method or a coating method; a physical method such as a vacuum deposition method, a sputtering method, or an ion plating method. And chemical methods such as CVD and plasma CVD. Among these, it can be formed on the substrate in accordance with an appropriately selected method in consideration of suitability with the material constituting the electrode. For example, when ITO is selected as the anode material, it can be formed according to a direct current or high frequency sputtering method, a vacuum deposition method, an ion plating method, or the like. When a metal or the like is selected as the cathode material, one or more of them can be formed simultaneously or sequentially according to a sputtering method or the like.

In addition, when patterning is performed when forming the electrode, it may be performed by chemical etching such as photolithography, or may be performed by physical etching using a laser or the like. It may be performed by sputtering or the like, or may be performed by a lift-off method or a printing method.

<< Board >>
The organic electroluminescent element is preferably provided on a substrate, and may be provided in such a manner that the electrode and the substrate are in direct contact with each other, or may be provided with an intermediate layer interposed therebetween.
There is no restriction | limiting in particular as a material of the said board | substrate, According to the objective, it can select suitably, For example, inorganic materials, such as a yttria stabilized zirconia (YSZ) and glass (an alkali free glass, soda-lime glass, etc.); Polyethylene Examples thereof include polyesters such as terephthalate, polybutylene phthalate, and polyethylene naphthalate; organic materials such as polystyrene, polycarbonate, polyethersulfone, polyarylate, polyimide, polycycloolefin, norbornene resin, and poly (chlorotrifluoroethylene).

The shape, structure, size and the like of the substrate are not particularly limited, and can be appropriately selected according to the use, purpose, etc. of the light emitting element. In general, the shape of the substrate is preferably a plate shape. The structure of the substrate may be a single layer structure, a laminated structure, may be formed of a single member, or may be formed of two or more members. The substrate may be transparent or opaque, and if transparent, it may be colorless and transparent or colored and transparent.

The substrate may be provided with a moisture permeation preventing layer (gas barrier layer) on the front surface or the back surface.
Examples of the material of the moisture permeation preventing layer (gas barrier layer) include inorganic substances such as silicon nitride and silicon oxide.
The moisture permeation preventing layer (gas barrier layer) can be formed by, for example, a high frequency sputtering method.

<< Protective layer >>
The entire organic electroluminescent element may be protected by a protective layer.
The material contained in the protective layer is not particularly limited as long as it has a function of suppressing the entry of elements that promote element deterioration such as moisture and oxygen into the element. For example, metals such as In, Sn, Pb, Au, Cu, Ag, Al, Ti, Ni; MgO, SiO, SiO ₂ , Al ₂ O ₃ , GeO, NiO, CaO, BaO, Fe Metal oxides such as ₂ O ₃ , Y ₂ O ₃ and TiO ₂ ; Metal nitrides such as SiNx and SiNxOy; Metal fluorides such as MgF ₂ , LiF, AlF ₃ and CaF ₂ ; polyethylene, polypropylene, polymethyl methacrylate, Polyimide, polyurea, polytetrafluoroethylene, polychlorotrifluoroethylene, polydichlorodifluoroethylene, chlorotrifluoroethylene And a copolymer of dichlorodifluoroethylene, a copolymer obtained by copolymerizing a monomer mixture containing tetrafluoroethylene and at least one comonomer, a fluorine-containing copolymer having a cyclic structure in the copolymer main chain, Examples thereof include a water-absorbing substance having a water absorption of 1% or more, a moisture-proof substance having a water absorption of 0.1% or less, and the like.

There is no restriction | limiting in particular as a formation method of the said protective layer, According to the objective, it can select suitably, For example, a vacuum evaporation method, sputtering method, reactive sputtering method, MBE (molecular beam epitaxy) method, cluster ion beam Examples thereof include an ion plating method, a plasma polymerization method (high frequency excitation ion plating method), a plasma CVD method, a laser CVD method, a thermal CVD method, a gas source CVD method, a coating method, a printing method, and a transfer method.

<< sealing container >>
The organic electroluminescent element may be entirely sealed using a sealing container. Furthermore, a water absorbent or an inert liquid may be sealed in the space between the sealing container and the organic electroluminescent element.
The moisture absorbent is not particularly limited and may be appropriately selected depending on the purpose. For example, barium oxide, sodium oxide, potassium oxide, calcium oxide, sodium sulfate, calcium sulfate, magnesium sulfate, phosphorus pentoxide, Examples include calcium chloride, magnesium chloride, copper chloride, cesium fluoride, niobium fluoride, calcium bromide, vanadium bromide, molecular sieve, zeolite, magnesium oxide, and the like.
The inert liquid is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include paraffins, liquid paraffins; fluorinated solvents such as perfluoroalkane, perfluoroamine, and perfluoroether; chlorine System solvents, silicone oils, and the like.

<< Resin sealing layer >>
The organic electroluminescent element is preferably suppressed by sealing the element performance deterioration due to oxygen or moisture from the atmosphere with a resin sealing layer.
The resin material of the resin sealing layer is not particularly limited and may be appropriately selected depending on the purpose. For example, acrylic resin, epoxy resin, fluorine resin, silicone resin, rubber resin, ester resin , Etc. Among these, an epoxy resin is particularly preferable from the viewpoint of moisture prevention function. Among the epoxy resins, a thermosetting epoxy resin or a photocurable epoxy resin is preferable.

There is no restriction | limiting in particular as a preparation method of the said resin sealing layer, According to the objective, it can select suitably, For example, the method of apply | coating a resin solution, the method of crimping | bonding or thermocompressing a resin sheet, vapor deposition, sputtering, etc. And a dry polymerization method.

<< Sealing adhesive >>
The sealing adhesive used in the present invention has a function of preventing intrusion of moisture and oxygen from the end portion.
As the material of the sealing adhesive, the same material as that used for the resin sealing layer can be used. Among these, an epoxy adhesive is preferable from the viewpoint of moisture prevention, and a photocurable adhesive or a thermosetting adhesive is more preferable.
It is also preferable to add a filler to the sealing adhesive. As the filler, for _example, SiO 2, SiO (silicon oxide), SiON (silicon oxynitride), an inorganic material such as SiN (silicon nitride) are preferred. Addition of the filler increases the viscosity of the sealing adhesive, improves processing suitability, and improves moisture resistance.
The sealing adhesive may contain a desiccant. Examples of the desiccant include barium oxide, calcium oxide, and strontium oxide. The addition amount of the desiccant is preferably 0.01% by mass to 20% by mass and more preferably 0.05% by mass to 15% by mass with respect to the sealing adhesive. When the addition amount is less than 0.01% by mass, the effect of adding the desiccant is diminished, and when it exceeds 20% by mass, it is difficult to uniformly disperse the desiccant in the sealing adhesive. Sometimes.
In the present invention, the sealing adhesive containing the desiccant can be applied by applying an arbitrary amount with a dispenser or the like, and the second substrate can be overlaid after application and cured.

FIG. 1 is a schematic view showing an example of a layer structure of the organic electroluminescent element. The organic electroluminescent element 10 includes an anode 2 (for example, an ITO electrode) formed on the glass substrate 1, a hole injection layer 3, a hole transport layer 4, a light emitting layer 5, an electron transport layer 6, It has a layer structure in which an electron injection layer 7 (for example, a lithium fluoride-containing layer) and a cathode 8 (for example, an Al—Li electrode) are stacked in this order. The anode 2 (for example, ITO electrode) and the cathode 8 (for example, Al—Li electrode) are connected to each other via a power source.

-Drive-
The organic electroluminescence device obtains light emission by applying a direct current (which may include an alternating current component as necessary) voltage (usually 2 to 15 volts) or a direct current between the anode and the cathode. Can do.
The organic electroluminescence device can be applied to an active matrix by a thin film transistor (TFT). As the active layer of the thin film transistor, amorphous silicon, high temperature polysilicon, low temperature polysilicon, microcrystalline silicon, oxide semiconductor, organic semiconductor, carbon nanotube, or the like can be used.
As the organic electroluminescent element, for example, a thin film transistor described in International Publication No. 2005/088726, Japanese Patent Application Laid-Open No. 2006-165529, US Patent Application Publication No. 2008 / 0237598A1, and the like can be applied.

The organic electroluminescent element is not particularly limited, and the light extraction efficiency can be improved by various known devices. For example, by processing the substrate surface shape (for example, forming a fine uneven pattern), controlling the refractive index of the substrate, ITO layer, organic layer, controlling the thickness of the substrate, ITO layer, organic layer, etc. It is possible to improve light extraction efficiency and external quantum efficiency.
The light extraction method from the organic electroluminescent element may be a top emission method or a bottom emission method.

The organic electroluminescent device may have a resonator structure. For example, a multilayer film mirror made of a plurality of laminated films having different refractive indexes, a transparent or translucent electrode, a light emitting layer, and a metal electrode are superimposed on a transparent substrate. The light generated in the light emitting layer resonates repeatedly with the multilayer mirror and the metal electrode as a reflection plate.
In another preferred embodiment, a transparent or translucent electrode and a metal electrode each function as a reflecting plate on a transparent substrate, and light generated in the light emitting layer repeats reflection and resonates between them.
In order to form a resonant structure, the optical path length determined from the effective refractive index of the two reflectors and the refractive index and thickness of each layer between the reflectors is adjusted to an optimum value to obtain the desired resonant wavelength. Is done. The calculation formula in the case of the first aspect is described in JP-A-9-180883. The calculation formula in the case of the second aspect is described in Japanese Patent Application Laid-Open No. 2004-127795.

-Applications-
The use of the organic electroluminescent element is not particularly limited and may be appropriately selected according to the purpose. Display element, display, backlight, electrophotography, illumination light source, recording light source, exposure light source, reading light source, It can be suitably used for signs, signboards, interiors, optical communications, and the like.
For example, as described in “Monthly Display”, September 2000, pages 33 to 37, the method using the organic electroluminescence device as a full color type is described in the three primary colors ( Three-color light emission method in which organic EL elements that emit light corresponding to blue (B), green (G), and red (R) are arranged on a substrate, and white light emitted by an organic electroluminescent element for white light emission is colored There are known a white method that divides three primary colors through a filter, a color conversion method that converts blue light emitted by an organic electroluminescent element for blue light emission into red (R) and green (G) through a fluorescent dye layer. Moreover, the planar light source of a desired luminescent color can be obtained by using combining the organic electroluminescent element of the different luminescent color obtained by the said method. For example, a white light-emitting light source combining blue and yellow light-emitting elements, a white light-emitting light source combining blue, green, and red light-emitting elements can be used.

Examples of the present invention will be described below, but the present invention is not limited to these examples.

Example 1
-Fabrication of organic electroluminescent elements-
A 0.7 mm thick, 25 mm square glass substrate was placed in a cleaning container, subjected to ultrasonic cleaning in 2-propanol, and then subjected to UV-ozone treatment for 30 minutes. The following layers were formed on this glass substrate. In addition, the vapor deposition rate in the following examples and comparative examples is 0.2 nm / second unless otherwise specified. The deposition rate was measured using a quartz resonator. The following layer thicknesses were measured using a stylus profilometer (XP-200, manufactured by AMBiOS Technology. Inc.). Moreover, the glass transition temperature Tg of each substance was measured with the following measuring method.

<Measuring method of glass transition temperature Tg>
The glass transition temperature Tg was measured from the endothermic change using a differential thermal thermogravimetric simultaneous measurement apparatus (EXSTAR TG / DTA6000, manufactured by Seiko Instruments Inc.).

First, ITO (Indium Tin Oxide) as a positive electrode was sputter-deposited on a glass substrate to a thickness of 150 nm. The obtained transparent support substrate was etched and washed.
Next, on the anode (ITO), 2 parts by mass of an arylamine derivative (trade name: PTPDES-2, manufactured by Chemipro Kasei, Tg = 205 ° C.) are dissolved in 98 parts by mass of cyclohexanone for electronics industry (manufactured by Kanto Chemical Co., Ltd.). The dispersed coating solution was spin-coated, dried at 120 ° C. for 30 minutes, and annealed at 160 ° C. for 10 minutes to form a hole injection layer having a thickness of about 40 nm.
Next, a compound represented by the following structural formula (9) as an arylamine derivative (Mw = 8,000, where the weight average molecular weight was calculated in terms of standard polystyrene using GPC (gel permeation chromatograph). .) 19 parts by mass and 1 part by mass of the compound represented by the following structural formula (10) were dissolved or dispersed in 2,000 parts by mass of xylene for electronic industry (manufactured by Kanto Chemical Co., Ltd.) and stirred for 1 hour. A hole transport layer coating solution was prepared. The hole transport layer coating solution is spin-coated on the hole injection layer, dried at 120 ° C. for 30 minutes, and annealed at 150 ° C. for 10 minutes to obtain a thickness of about 15 nm and a glass transition temperature (Tg) = 160. A hole transport layer having a temperature of at least ° C. was formed. The weight average molecular weight of the structural formula (9) was measured as follows, and the spin injection of the hole injection layer and the hole transport layer was performed in a glove box (dew point −70 ° C., oxygen concentration 8 ppm). .

Next, on the hole transport layer, 9 parts by mass of a compound (Tg = 115 ° C.) represented by the following structural formula (1) as a host material and the following structural formula (7) as a phosphorescent material are represented. 1 part by mass of a compound (trade name: Ir (ppy) 3, manufactured by Chemipro Kasei Co., Ltd.) is dissolved or dispersed in 990 parts by mass of 2-butanone (boiling point: 79.5 ° C., manufactured by Kanto Chemical Co., Ltd.) for electronic industry. A light emitting layer coating solution prepared by adding molecular sieve (trade name: Molecular sieve 5A 1/16, manufactured by Wako Pure Chemical Industries, Ltd.) and filtering with a syringe filter having a pore diameter of 0.22 μm in a glove box, A light emitting layer having a thickness of 30 nm was formed by spin coating in a glove box and drying at 125 ° C. for 30 minutes.

Next, BAlq (Bis- (2-methyl-8-quinolinolato) -4- (phenyl-phenolate) -aluminum- (III)) was deposited on the light-emitting layer by a vacuum deposition method, thereby forming an electron having a thickness of 40 nm. A transport layer was formed.
Next, lithium fluoride (LiF) was deposited on the electron transport layer to form an electron injection layer having a thickness of 1 nm.
Next, metal aluminum was vapor-deposited on the electron injection layer to form a cathode having a thickness of 70 nm.
The produced laminate was put in a glove box substituted with argon gas, and sealed with a stainless steel sealing can and an ultraviolet curable adhesive (XNR5516HV, manufactured by Nagase Ciba Co., Ltd.).

The synthesis scheme of the compound represented by the structural formula (1) is as follows.

(Comparative Example 1A)
In Example 1, instead of spin-coating the luminescent layer coating solution in a glove box and drying at 125 ° C. for 30 minutes to form the luminescent layer, the luminescent layer coating solution was spin-coated in the glove box at 85 ° C. An organic electroluminescent element was produced in the same manner as in Example 1 except that the light emitting layer was formed by drying for 30 minutes.

(Comparative Example 1B)
In Example 1, instead of forming the light emitting layer by spin coating the light emitting layer coating solution in a glove box and drying at 125 ° C. for 30 minutes, the light emitting layer coating solution was spin coated in a glove box at 100 ° C. The organic electroluminescence device was produced in the same manner as in Example 1 except that the light emitting layer was formed by drying for 30 minutes.

(Example 2)
In Example 1, in the formation of the light emitting layer, instead of using a compound represented by the following structural formula (7) as a phosphorescent material and using 2-butanone for electronics industry as a solvent and drying at 125 ° C. for 30 minutes In addition, a compound represented by the following structural formula (8) is used as a phosphorescent material, and xylene for electronic industry (boiling point 144 ° C., manufactured by Kanto Chemical Co.) and dehydrated toluene (boiling point 110 ° C., Wako Pure Chemical Industries, Ltd.) are used as solvents. An organic electroluminescent device was prepared in the same manner as in Example 1 except that the mixture was dried at 125 ° C. for 30 minutes and further annealed at 150 ° C. for 10 minutes using a mixed solvent (mixed ratio of 2/8). did.

(Comparative Example 2)
In Example 2, an organic electroluminescent element was produced in the same manner as in Example 2 except that the annealing process was not performed at 150 ° C. for 10 minutes in forming the light emitting layer.

(Example 3)
In Example 1, instead of using the compound represented by the structural formula (1) as a host material in the formation of the light emitting layer, a compound represented by the following structural formula (2) (glass transition temperature (Tg) = 102 ° C.), and in Example 1, in the formation of the light emitting layer, instead of drying at 125 ° C. for 30 minutes, instead of drying at 120 ° C. for 30 minutes, the same as in Example 1, An organic electroluminescent element was produced.

(Comparative Example 3)
In Example 3, an organic electroluminescent element was produced in the same manner as in Example 3 except that, in the formation of the light emitting layer, instead of drying at 120 ° C. for 30 minutes, drying was performed at 85 ° C. for 30 minutes.

Example 4
In Example 1, instead of using the compound represented by the structural formula (1) as a host material in forming the light emitting layer, the compound represented by the following structural formula (3) (glass transition temperature) was used as the host material. (Tg) = 122 ° C.) and in Example 1, except that in the formation of the light emitting layer, drying was performed at 130 ° C. for 30 minutes instead of drying at 125 ° C. for 30 minutes. In the same manner as in Example 1, an organic electroluminescent element was produced.

The synthesis scheme of the compound represented by the structural formula (3) is as follows.
<Synthesis Scheme of Compound Represented by Structural Formula (3)>

(Comparative Example 4)
In Example 4, an organic electroluminescent device was produced in the same manner as in Example 4 except that, in the formation of the light emitting layer, instead of drying at 130 ° C. for 30 minutes, drying was performed at 85 ° C. for 30 minutes.

(Example 5)
In Example 1, instead of using the compound represented by the structural formula (1) as a host material in forming the light emitting layer, the compound represented by the following structural formula (4) (glass transition temperature) was used as the host material. (Tg) = 105 ° C.) In Example 1, except that, in the formation of the light emitting layer, instead of drying at 125 ° C. for 30 minutes, drying was performed at 120 ° C. for 30 minutes. In the same manner as in Example 1, an organic electroluminescent element was produced.

(Comparative Example 5)
In Example 5, an organic electroluminescent element was produced in the same manner as in Example 5 except that, in the formation of the light emitting layer, instead of drying at 120 ° C. for 30 minutes, drying was performed at 85 ° C. for 30 minutes.

(Example 6)
-Fabrication of organic electroluminescent elements-
A 0.7 mm thick, 25 mm square glass substrate was placed in a cleaning container, subjected to ultrasonic cleaning in 2-propanol, and then subjected to UV-ozone treatment for 30 minutes. The following layers were formed on this glass substrate. In addition, the vapor deposition rate in the following examples and comparative examples is 0.2 nm / second unless otherwise specified. The deposition rate was measured using a quartz resonator. The following layer thicknesses were measured using a stylus profilometer (XP-200, manufactured by AMBiOS Technology. Inc.).

First, ITO (Indium Tin Oxide) as a positive electrode was sputter-deposited on a glass substrate to a thickness of 150 nm. The obtained transparent support substrate was etched and washed.
Next, 90 parts by mass of a hole injection material (trade name: CLEVIOS P AI4083, manufactured by HC Stack, Tg = 190 ° C.) and 10 parts by mass of ethanol were prepared on the anode (ITO). After spin-coating the coating solution, it was dried at 100 ° C. for 10 minutes and vacuum dried at 160 ° C. for 120 minutes to form a 40 nm thick hole injection layer.

Next, on the hole injection layer, 9 parts by mass of a compound (Tg = 124 ° C.) represented by the following structural formula (5) as a host material and the above structural formula (7) as a phosphorescent material are represented. 1 part by mass of a compound (trade name: Ir (ppy) 3, manufactured by Chemipro Chemical Co., Ltd.) is dissolved or dispersed in 990 parts by mass of 2-methyltetrahydrofuran (boiling point 78 ° C., manufactured by Tokyo Chemical Industry Co., Ltd.) for electronic industry. A light-emitting layer coating solution prepared by adding a sieve (trade name: Molecular sieve 5A 1/16, manufactured by Wako Pure Chemical Industries, Ltd.) and filtering with a syringe filter having a pore size of 0.22 μm in a glove box It spin-coated in the box, and it dried for 30 minutes at 160 degreeC, and formed the light emitting layer with a thickness of 30 nm.

The synthesis scheme of the compound represented by the structural formula (5) is as follows.
<Synthesis Scheme of Compound Represented by Structural Formula (5)>

(Comparative Example 6)
In Example 6, an organic electroluminescent device was produced in the same manner as in Example 6 except that, in the formation of the light emitting layer, instead of drying at 160 ° C. for 30 minutes, drying was performed at 80 ° C. for 30 minutes.

(Example 7)
In Example 6, 90 parts by mass of a hole injection material (trade name: CLEVIOS P AI4083, manufactured by HC Stack, glass transition temperature (Tg) = 190 ° C.) and 10 parts by mass of ethanol were mixed on the anode. After spin coating the prepared coating solution, it was dried at 100 ° C. for 10 minutes and vacuum dried at 160 ° C. for 120 minutes to form a hole injection layer having a thickness of about 40 nm. Compound represented by the above structural formula (9) as an amine derivative (weight average molecular weight (Mw) = 8,000, glass transition temperature 140 ° C., where the weight average molecular weight is determined using GPC (gel permeation chromatograph). 2 parts by mass of a mixed solvent of dehydrated tetrahydrofuran (manufactured by Kanto Chemical Co., Inc.) and dehydrated toluene (manufactured by Kanto Chemical Co., Ltd.) Mixing ratio 7: 3) Spin coating the coating solution dissolved or dispersed in 98 parts by mass, followed by drying at 120 ° C. for 30 minutes and annealing at 130 ° C. for 10 minutes to form a hole injection layer having a thickness of about 40 nm. (In Example 6, 9 parts by mass of the compound represented by the structural formula (5) as a host material and the structural formula (7) as a phosphorescent material are formed on the hole injection layer. A light emitting layer coating solution prepared by dissolving and dispersing 1 part by mass of the compound represented by the formula in 990 parts by mass of 2-methyltetrahydrofuran for electronics industry is spin-coated in a glove box and dried at 160 ° C. for 30 minutes. Instead of forming a light emitting layer having a thickness of 30 nm, a compound represented by the following structural formula (6) as a host material (glass transition temperature (Tg) = 112 ° C.) 4.5 mass on the hole injection layer And phosphorescence Luminescent layer coating prepared by dissolving or dispersing 0.5 parts by mass of the compound represented by the structural formula (7) as an optical material in 995 parts by mass of methyl isobutyl ketone (boiling point 116 ° C., manufactured by Kanto Chemical Co., Inc.). An organic electroluminescent element was produced in the same manner as in Example 6 except that the liquid was spray-coated and dried at 125 ° C. for 30 minutes to form a 30 nm thick light emitting layer.

The synthesis scheme of the compound represented by the structural formula (6) is as follows.
<Synthesis Scheme of Compound Represented by Structural Formula (6)>

(Example 8)
In Example 7, in the formation of the light emitting layer, instead of drying at 125 ° C. for 30 minutes, instead of drying at 125 ° C. for 30 minutes and further annealing at 160 ° C. for 10 minutes, the same as in Example 7, An organic electroluminescent element was produced.

(Comparative Example 7)
In Example 7, an organic electroluminescence device was produced in the same manner as in Example 7 except that, in the formation of the light emitting layer, instead of drying at 125 ° C. for 30 minutes, drying was performed at 100 ° C. for 30 minutes.

(Comparative Example 8)
In Example 6, 9 parts by mass of the compound represented by the structural formula (5) as the host material and 1 mass of the compound represented by the structural formula (7) as the phosphorescent material on the hole injection layer. A luminescent layer coating solution prepared by dissolving or dispersing in 990 parts by mass of 2-methyltetrahydrofuran for electronics industry, spin-coated in a glove box, and dried at 160 ° C. for 30 minutes to give a luminescent layer having a thickness of 30 nm On the hole injection layer, 4.5 parts by mass of a dicarbazole derivative (CBP) as a host material and 0.5 parts by mass of the compound represented by the structural formula (7) as a phosphorescent material are used. A luminescent layer coating solution prepared by dissolving or dispersing in 995 parts by mass of xylene (boiling point 144 ° C., manufactured by Kanto Chemical Co., Ltd.), spray-dried, dried at 155 ° C. for 30 minutes, and luminescent layer having a thickness of 30 nm The Except that none, in the same manner as in Example 6, to manufacture an organic electroluminescence device.
As a result, the light emitting layer became cloudy. This white turbidity of the light emitting layer is considered to have occurred because the dicarbazole derivative (CBP) was crystallized by heating.

Example 9
In Example 1, in the formation of the light emitting layer, the compound represented by the structural formula (1) is used as the host material, and the phosphorescent light emitting material is replaced with the structural formula (7). Using the compound represented by the structural formula (11) (glass transition temperature (Tg) = 125 ° C.), using the following structural formula (12) as the phosphorescent material, and in Example 1, in forming the light emitting layer An organic electroluminescence device was produced in the same manner as in Example 1 except that drying at 140 ° C. for 30 minutes was performed instead of drying at 125 ° C. for 30 minutes.

(Comparative Example 9)
In Example 9, an organic electroluminescence device was produced in the same manner as in Example 9 except that, in the formation of the light emitting layer, instead of drying at 140 ° C. for 30 minutes, drying was performed at 85 ° C. for 30 minutes.

(Comparative Example 10)
In Example 1, in the formation of the light emitting layer, an organic electric field was obtained in the same manner as in Example 1 except that the compound of the structural formula (12) was used as the phosphorescent light emitting material and was dried at 115 ° C. for 30 minutes. A light emitting element was manufactured.
When this element was energized, red EL light emission was observed.

(Example 10)
-Fabrication of organic electroluminescent elements-
A 0.7 mm thick, 25 mm square glass substrate was placed in a cleaning container, subjected to ultrasonic cleaning in 2-propanol, and then subjected to UV-ozone treatment for 30 minutes. The following layers were formed on this glass substrate. The deposition rate was measured using a quartz resonator.

First, ITO (Indium Tin Oxide) as a positive electrode was sputter-deposited on a glass substrate to a thickness of 150 nm. The obtained transparent support substrate was etched and washed.
Next, on the anode (ITO), a hole injection layer coating solution in which 5 parts by mass of a compound of the following structural formula A was dissolved or dispersed in 995 parts by mass of cyclohexanone for electronics industry (manufactured by Kanto Chemical Co., Inc.) was spin coated. Then, it dried at 200 degreeC for 30 minute (s), and formed the 5-nm-thick hole injection layer.

Next, 10 parts by mass of the compound of the following structural formula B was dissolved in 990 parts by mass of toluene (dehydrated) (manufactured by Wako Pure Chemical Industries, Ltd.) to prepare a hole transport layer coating solution. This hole transport layer coating solution was spin-coated on the hole injection layer and dried at 200 ° C. for 30 minutes to form a hole transport layer having a thickness of 18 nm.

Next, 9 parts by mass of a compound (glass transition temperature (Tg) = 141 ° C.) represented by the following structural formula C (Exemplary Compound 22 described in JP-A No. 2001-33576) as a host material on the hole transport layer; In addition, 1 part by mass of a compound represented by the following structural formula D as a phosphorescent material is dissolved or dispersed in 990 parts by mass of 2-butanone (boiling point 88 ° C., manufactured by Kanto Chemical Co., Inc.) for electronic industry. Name: Molecular sieve 3A 1/16, manufactured by Wako Pure Chemical Industries, Ltd.) was added, and the luminous layer coating solution prepared by filtration using a syringe filter with a pore size of 0.22 μm in the glove box was used in the glove box. It spin-coated and dried for 30 minutes at 150 degreeC, and formed the light emitting layer with a thickness of 30 nm.

(Comparative Example 11)
In Example 10, an organic electroluminescent element was produced in the same manner as in Example 10 except that the drying temperature was changed from 150 ° C to 120 ° C.

(Example 11)
In Example 10, instead of using the compound represented by the above structural formula C (glass transition temperature (Tg) = 141 ° C.) as the host material, Exemplified Compound 26 described in the following structural formula E (Japanese Patent Application Laid-Open No. 2001-335776) The organic electroluminescence device was produced in the same manner as in Example 10 except that the drying temperature was changed from 150 ° C. to 145 ° C. using the compound represented by (). (Glass transition temperature (Tg) = 136 ° C.) .

(Comparative Example 12)
In Example 11, an organic electroluminescent element was produced in the same manner as in Example 11 except that the drying temperature was changed from 145 ° C. to 120 ° C.

(Example 12)
In Example 10, instead of using the compound represented by the structural formula C (glass transition temperature (Tg) = 141 ° C.) as the host material, the compound represented by the structural formula (11) (glass transition temperature (Tg) ) = 125 ° C.) and an organic electroluminescence device was produced in the same manner as in Example 10 except that the drying temperature was changed from 150 ° C. to 140 ° C.

(Comparative Example 13)
In Example 12, an organic electroluminescent element was produced in the same manner as in Example 12 except that the drying temperature was changed from 140 ° C to 120 ° C.

Next, for the organic electroluminescent devices of Examples 1 to 12 and Comparative Examples 1 to 13, the external quantum efficiency and the rate of change in luminance attenuation (20% attenuation time) in each layer were measured as follows. .

<Measurement of external quantum efficiency>
Using a source measure unit 2400 manufactured by Toyo Technica Co., Ltd., a DC voltage was applied to each element at room temperature to drive continuously and emit light. The emission spectrum / luminance was measured using a spectrum analyzer SR-3 manufactured by Topcon Corporation, and the external quantum efficiency at a current of 10 mA / cm ² was calculated by the luminance conversion method based on these numerical values. The results are shown in Tables 1 to 11.

<Change rate of luminance decay (20% decay time)>
From the luminance data measured using the spectrum analyzer SR-3 manufactured by Topcon Corporation, as shown in FIG. 2, when the luminance 1,000 cd / m ² immediately after the start of driving is set to 100%, the luminance is attenuated by 20%. The time to 80% was used as an index of the rate of change in luminance attenuation. The results are shown in Tables 1 to 11.
In Table 1, Comparative Example 1B is used as a reference, in Table 2, Comparative Example 2 is used as a reference, in Table 3, Comparative Example 3 is used as a reference, in Table 4, Comparative Example 4 is used as a reference, and in Table 5, Based on Comparative Example 5, Table 6 uses Comparative Example 6 as a standard, Table 7 uses Comparative Example 7 as a standard, Table 8 uses Comparative Example 9 as a standard, and Table 9 uses Comparative Example 11 as a standard. In Table 10, Comparative Example 12 is used as a reference, and in Table 11, Comparative Example 13 is used as a reference. In Examples and Comparative Examples other than the reference, the external quantum efficiency and the luminance attenuation change rate (20% attenuation time) of the comparative example based on the reference were set to 1, and relative values were shown.

From Table 1, it was found that Example 1 has the same external quantum efficiency as Comparative Examples 1A and 1B, and the rate of change in luminance attenuation is smaller (20% attenuation time is longer) than Comparative Examples 1A and 1B.
Further, Table 2 shows that Example 2 has higher external quantum efficiency than Comparative Example 2, and has a smaller rate of change in luminance attenuation than Comparative Example 2 (20% attenuation time is longer).
In addition, Table 3 shows that Example 3 has the same external quantum efficiency as Comparative Example 3, and the rate of change in luminance attenuation is smaller than that of Comparative Example 3 (20% attenuation time is longer).
Table 4 also shows that Example 4 has the same external quantum efficiency as that of Comparative Example 4, and the rate of change in luminance attenuation is smaller than that of Comparative Example 4 (20% attenuation time is longer).
Table 5 also shows that Example 5 has the same external quantum efficiency as that of Comparative Example 5, and the rate of change in luminance attenuation is smaller than that of Comparative Example 5 (20% attenuation time is longer).
Table 6 also shows that Example 6 has the same external quantum efficiency as that of Comparative Example 6, and the rate of change in luminance attenuation is smaller than that of Comparative Example 6 (20% attenuation time is longer).
Table 7 also shows that Example 7 has the same external quantum efficiency as that of Comparative Example 7, and the rate of change in luminance attenuation is smaller than that of Comparative Example 7 (20% attenuation time is longer).
In addition, Table 7 shows that Example 8 has higher external quantum efficiency than Comparative Example 7, and the rate of change in luminance attenuation is smaller than that of Comparative Example 7 (20% attenuation time is longer).
Further, from Table 7, Example 8 heated at the glass transition temperature (140 ° C.) or higher of the hole injection layer is more positive than Example 7 not heated above the glass transition temperature of the hole injection layer. It was found that since the mixing of the interface between the hole injection layer and the light emitting layer occurs more, the external quantum efficiency is improved and the rate of change in luminance attenuation is increased (20% attenuation time is shortened).
Table 8 also shows that Example 9 has the same external quantum efficiency as that of Comparative Example 9, and the rate of change in luminance attenuation is smaller than that of Comparative Example 9 (20% attenuation time is longer).
Table 9 also shows that Example 10 has the same external quantum efficiency as Comparative Example 11 and a smaller change rate of luminance attenuation than that of Comparative Example 11 (20% attenuation time is longer).
Table 10 also shows that Example 11 has the same external quantum efficiency as that of Comparative Example 12, and the rate of change in luminance attenuation is smaller than that of Comparative Example 12 (20% attenuation time is longer).
Table 11 also shows that Example 12 has the same external quantum efficiency as that of Comparative Example 13, and the rate of change in luminance attenuation is smaller than that of Comparative Example 13 (20% attenuation time is longer).

Since the organic electroluminescent device produced by the method of the present invention can achieve both excellent luminous efficiency and luminous lifetime, for example, display device, display, backlight, electrophotography, illumination light source, recording light source, exposure light source It is suitably used for reading light sources, signs, signboards, interiors, optical communications, and the like.

DESCRIPTION OF SYMBOLS 1 Board | substrate 2 Anode 3 Hole injection layer 4 Hole transport layer 5 Light emitting layer 6 Electron transport layer 7 Electron injection layer 8 Cathode 10 Organic electroluminescent element

Claims

A method for producing an organic electroluminescent device comprising an organic layer including a light emitting layer between an anode and a cathode,
The light emitting layer is coated with a coating solution prepared by dissolving or dispersing a light emitting material and a host material represented by at least one of the following general formula (1) and the following general formula (2) in a solvent, A method for producing an organic electroluminescent element, wherein the organic electroluminescent element is formed by heating at a temperature higher than the glass transition temperature of the solvent and higher than the boiling point of the solvent.

In the general formula (1), R represents any one of t-butyl group, t-amyl group, trimethylsilyl group, triphenylsilyl group and phenyl group, and R 1 to R 23 each represents a hydrogen atom. , T-butyl group, t-amyl group, trimethylsilyl group, triphenylsilyl group, phenyl group, cyano group and alkyl group having 1 to 5 carbon atoms.

However, in said general formula (2), R represents arbitrary substituents.
The method for producing an organic electroluminescent element according to claim 1, wherein the molecular weight of the light emitting material is 1,500 or less and the molecular weight of the host material is 1,500 or less.
The organic electric field according to claim 1, wherein the host material represented by the general formula (1) is a compound represented by any one of the following structural formulas (1) to (6) and (11). Manufacturing method of light emitting element.
The method for producing an organic electroluminescent element according to any one of claims 1 to 3, wherein the host material represented by the general formula (2) is a compound represented by any one of the following structural formulas C and E.
5. The method for producing an organic electroluminescent element according to claim 1, wherein the solvent is at least one selected from 2-butanone, xylene, toluene, 2-methyltetrahydrofuran, and methyl isobutyl ketone.
The method for producing an organic electroluminescent element according to claim 1, wherein the luminescent material is a compound represented by any one of the following structural formulas (7), (8), (12) and D.
The method for producing an organic electroluminescent element according to any one of claims 1 to 6, wherein the heating temperature is 10 ° C or more higher than the glass transition temperature of the host material and 45 ° C or higher than the boiling point of the solvent.