JP2012084415A - Method for manufacturing organic electroluminescent element and organic electroluminescent element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing an organic electroluminescent element less in luminance unevenness while securing characteristics of high luminous efficiency and long life of the element itself.SOLUTION: In an organic electroluminescent element, an anode, a cathode and a luminous layer are formed on a substrate, and the luminous layer is interposed between the anode and the cathode and contains a light emitting host and a light emitting dopant. A method for manufacturing the organic electroluminescent element according to the present invention includes a step of laminating two or more kinds of coating liquids having different dopant concentrations by means of a die coating method to form the luminous layer. In the step of forming the luminous layer, a dopant concentration gradient is formed in the thickness direction of the luminous layer.

Description

  The present invention relates to a method for manufacturing an organic electroluminescence device and organic electroluminescence, and is particularly capable of being manufactured by a simple process, improving the light emission efficiency and lifetime, and reducing the luminance unevenness, and the method thereof. The present invention relates to a manufactured organic electroluminescence device.

As a light-emitting electronic display device, there is an electroluminescence display (hereinafter abbreviated as ELD). As an ELD component, an inorganic electroluminescence element (hereinafter also referred to as an inorganic EL element) and an organic electroluminescence element (hereinafter also referred to as an organic EL element) can be given. Inorganic EL elements have been used as planar light sources, but an alternating high voltage is required to drive the light emitting elements.
On the other hand, an organic electroluminescence device has a structure in which a light emitting layer containing a compound that emits light is sandwiched between a cathode and an anode, and excitons (excitons) by injecting electrons and holes into the light emitting layer and recombining them. Is a device that emits light by using light emission (fluorescence / phosphorescence) when this exciton is deactivated, and can emit light at a voltage of several V to several tens of V, and further self-emission. Since it is a type, it has a wide viewing angle, high visibility, and since it is a thin-film type completely solid element, it has attracted attention from the viewpoints of space saving, portability, and the like.
Another major feature of the organic electroluminescence element is that it is a surface light source, unlike main light sources that have been put to practical use, such as light-emitting diodes and cold-cathode tubes. Applications that can effectively utilize this characteristic include illumination light sources and various display backlights. In particular, it is also suitable to be used as a backlight of a liquid crystal full color display whose demand has been increasing in recent years.

Improvement of luminous efficiency is mentioned as a subject for using an organic electroluminescent element as such a light source for illumination, or a backlight of a display. In order to improve luminous efficiency, it is common to incorporate a so-called host / guest structure in which a part of the organic functional layer constituting the organic electroluminescence element is composed of a mixture of materials having different functions. It is becoming.
Specifically, a combination of a host material / a light emitting dopant in the light emitting layer can be given. The ratio of the light-emitting dopant to the light-emitting host in the light-emitting layer is continuously changed in the light-emitting layer, indicating that the lifetime is improved (for example, see Patent Documents 1 and 2). What is clearly shown as the means for changing to is only the control of the deposition rate in the vacuum deposition method, and cannot be said to be a proposal of means suitable for productivity.

On the other hand, as a method for producing these organic electroluminescence elements, there are a vapor deposition method, a wet process (spin coating method, cast method, ink jet method, spray method, printing method), etc., but a vacuum process is not required and continuous production is possible. In recent years, a manufacturing method in a wet process has attracted attention because of its simplicity.
As a method of providing a concentration gradient by continuously changing the concentration of the light-emitting dopant in the wet process, the application of two or more types of light-emitting layer solutions having different light-emitting dopant concentrations is performed. A method is disclosed in which the ratio is made higher than the light emitting dopant / light emitting host ratio of the solution coated on the cathode side, and then dried (see, for example, Patent Document 3).

Japanese Patent Laid-Open No. 2004-6102 JP 2003-229272 A International Publication No. 2009/084413

However, in this method, since the light emitting layer solution is applied by the ink jet method, the time from the formation of the liquid film after the application to the drying varies in time within the substrate surface, and the dopant concentration gradient varies depending on the location. Further, luminance unevenness occurs in the light emitting surface, and since the time from the formation of the coating liquid film to the drying is slow, the diffusion of the dopant in the film thickness direction proceeds excessively, and it is difficult to form a sufficient concentration gradient.
Accordingly, a main object of the present invention is to provide a method for manufacturing an organic electroluminescence element with less luminance unevenness while ensuring the characteristics of the element itself with high luminous efficiency and long life.

In order to solve the above problems, according to the present invention,
In the method for producing an organic electroluminescence device, an anode, a cathode and a light emitting layer are formed on a substrate, the light emitting layer is interposed between the anode and the cathode, and the light emitting host and the light emitting dopant are contained.
A step of forming the light emitting layer by laminating two or more kinds of coating liquids having different dopant concentrations by a die coating method;
In the step of forming the light emitting layer, a dopant concentration gradient is formed in the thickness direction of the light emitting layer, and a method for manufacturing an organic electroluminescent element is provided.

  ADVANTAGE OF THE INVENTION According to this invention, an organic electroluminescent element with few brightness irregularities can be stably manufactured with a wet process, ensuring the characteristic of the element itself of high luminous efficiency and long lifetime.

  Hereinafter, embodiments for carrying out the present invention will be described in detail.

According to a preferred embodiment of the present invention, there is provided a method of manufacturing an organic electroluminescence device comprising: an anode, a cathode, and a light emitting layer formed on a substrate; the light emitting layer interposed between the anode and the cathode; And a method for producing an organic electroluminescence device containing a light emitting dopant, comprising a step of forming the light emitting layer by laminating two or more coating solutions having different dopant concentrations by a die coating method, and forming the light emitting layer In this step, a dopant concentration gradient is formed in the thickness direction of the light emitting layer.
For example, when two types of coating liquids are used, the step of forming the light emitting layer includes a step of discharging the first coating liquid to form the first layer, and the first coating liquid has a dopant concentration. A step of forming and laminating a second layer on the first layer by discharging a different second coating liquid, and the thickness direction of the light emitting layer from the first layer toward the second layer To form a dopant concentration gradient.
The die coating method is a method of forming a coating film by discharging a coating liquid from a slit of a die head and moving the die head or the substrate in the coating direction.

  In the present invention, a desired dopant concentration gradient can be formed by appropriately adjusting the dopant concentrations of the two or more light emitting layer coating solutions and applying them by a die coating method. That is, two or more types of light emitting layer coating liquids having different dopant concentrations are formed by die coating to form a coating liquid film, and the dopant is appropriately dissolved and diffused while the liquid film is held, whereby the film thickness of the light emitting layer is obtained. It is possible to form a concentration gradient that is inclined in the direction.

In the present invention, when two or more kinds of coating liquids having different dopant concentrations are applied by the die coating method, two or more kinds of coating liquids having different dopant concentrations may be applied by simultaneously discharging from two or more discharge ports. You may discharge a liquid separately for every layer.
In the present invention, it is preferable to discharge the coating liquid separately for each layer from the viewpoint that the diffusion of the dopant can be further controlled. When multilayer coating is simultaneously applied from two or more discharge ports, it is preferable that two or more different coating liquids are the same solvent in order to diffuse the dopant of the light emitting layer.

  In addition, when two or more kinds of coating liquids having different dopant concentrations are applied to each layer by the die coating method, the second and subsequent coating liquids are applied at a coating speed of 1 m / min or more, and the second and subsequent layers are applied. The coating solution is blown within 5 seconds immediately after coating, or the coating solution is heated within 5 seconds immediately after coating to evaporate the solvent of the coating solution. A film thickness of 1 to 10 μm is preferable for producing a device with little luminance unevenness on the entire coated surface (light emitting surface) and high luminous efficiency and long life.

In the present invention, the dopant concentration gradient is preferably decreased from the anode side toward the cathode side in order to obtain an organic EL device having higher luminous efficiency and longer life.
In this case, among the two or more kinds of coating liquids having different dopant concentrations, the coating liquid that is applied to the anode side is made higher than the dopant concentration of the coating liquid that is applied to the cathode side. it can.
In the present invention, among the two or more kinds of light emitting layer coating liquids having different light emitting dopant concentrations, the light emitting dopant / light emitting host ratio of the coating liquid coated on the most anode side is 100 to 30%, and the coating liquid coated on the most cathode side. The luminescent dopant / luminescent host ratio is preferably 20 to 0%.
When the dopant is a phosphorescent dopant containing a heavy atom metal, the dopant concentration distribution in the light emitting layer formed in the present invention is determined by TOF-SIMS (time-of-flight secondary ion mass spectrometry) in the film thickness direction. It can be detected by analyzing the metal atom distribution.

  Hereinafter, details of each component of the organic electroluminescence element manufactured by the process of the present invention (hereinafter, also referred to as the organic EL element of the present invention) will be sequentially described.

<< Layer structure of organic EL element >>
Next, although the preferable specific example of the layer structure of the organic EL element of this invention is shown below, this invention is not limited to these.
(I) anode / light emitting layer / electron transport layer / cathode (ii) anode / hole injection layer / light emitting layer / electron injection layer / cathode (iii) anode / hole injection layer / hole transport layer / light emitting layer / electron Injection layer / cathode (iv) anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode

<Light emitting layer>
The light emitting layer according to the present invention is a layer that emits light by recombination of electrons and holes injected from the electrode, the electron transport layer, or the hole transport layer, and the light emitting portion is in the layer of the light emitting layer. May be the interface between the light emitting layer and the adjacent layer.
The thickness of the light emitting layer is not particularly limited, but from the viewpoint of improving the uniformity of the film to be formed and applying an unnecessary high voltage during light emission, and improving the stability of the emission color with respect to the driving current. It is preferable to adjust to a range of 200 nm, more preferably to a range of 5 nm or more and 100 nm or less.

  Hereinafter, the light emitting dopant and the light emitting host contained in the light emitting layer will be described.

(1) Luminescent Host As the host compound contained in the light emitting layer of the organic EL device of the present invention, a compound having a phosphorescence quantum yield of phosphorescence emission at room temperature (25 ° C.) of less than 0.1 is preferable. More preferably, the phosphorescence quantum yield is less than 0.01. Moreover, it is preferable that the volume ratio in the layer is 50% or more among the compounds contained in a light emitting layer.
As the host compound, known host compounds may be used alone or in combination of two or more. By using a plurality of types of host compounds, it is possible to adjust the movement of charges, and the organic EL element can be made highly efficient. Moreover, it becomes possible to mix different light emission by using multiple types of luminescent material mentioned later, and can thereby obtain arbitrary luminescent colors.
The host compound used in the present invention may be a conventionally known low molecular compound or a high molecular compound having a repeating unit, and a low molecular compound having a polymerizable group such as a vinyl group or an epoxy group (evaporation polymerizable light emitting host). )
As the known host compound, a compound having a hole transporting ability and an electron transporting ability, preventing an increase in the wavelength of light emission, and having a high Tg (glass transition temperature) is preferable. Here, the glass transition point (Tg) is a value obtained by a method based on JIS-K-7121 using DSC (Differential Scanning Colorimetry).

Specific examples of known host compounds include compounds described in the following documents. For example, Japanese Patent Application Laid-Open Nos. 2001-257076, 2002-308855, 2001-313179, 2002-319491, 2001-357777, 2002-334786, 2002-8860 Gazette, 2002-334787 gazette, 2002-15871 gazette, 2002-334788 gazette, 2002-43056 gazette, 2002-334789 gazette, 2002-75645 gazette, 2002-338579 gazette. No. 2002-105445, No. 2002-343568, No. 2002-141173, No. 2002-352957, No. 2002-203683, No. 2002-363227, No. 2002-231453. No. 2003-3165, No. 2002-234888, No. 2003-27048, No. 2002-255934, No. 2002-286061, No. 2002-280183, No. 2002-299060. 2002-302516, 2002-305083, 2002-305084, 2002-308837, and the like.
The host compound used in the present invention is preferably a carbazole derivative, more preferably a carbazole derivative and a dibenzofuran compound.

(2) Luminescent dopant As the luminescent dopant according to the present invention, a fluorescent dopant or a phosphorescent dopant can be used. From the viewpoint of obtaining an organic EL element with higher luminous efficiency, the luminescent layer of the organic EL element of the present invention. As a light-emitting dopant used in the light-emitting unit, it is preferable to contain a phosphorescent dopant at the same time as containing the light-emitting host.

(2.1) Phosphorescent dopant The phosphorescent dopant according to the present invention is a compound in which light emission from an excited triplet is observed, specifically, a compound that emits phosphorescence at room temperature (25 ° C.). The phosphorescence quantum yield is defined as a compound of 0.01 or more at 25 ° C., but the preferred phosphorescence quantum yield is 0.1 or more.
The phosphorescence quantum yield can be measured by the method described in Spectroscopic II, page 398 (1992 edition, Maruzen) of Experimental Chemistry Course 4 of the 4th edition. Although the phosphorescence quantum yield in a solution can be measured using various solvents, the phosphorescence dopant according to the present invention achieves the phosphorescence quantum yield (0.01 or more) in any solvent. That's fine.
There are two types of emission of phosphorescent dopants in principle. One is the recombination of carriers on the light-emitting host on which carriers are transported to generate the excited state of the light-emitting host, and this energy is transferred to the phosphorescent dopant. Energy transfer type to obtain light emission from the phosphorescent dopant, another is that the phosphorescent dopant becomes a carrier trap, carrier recombination occurs on the phosphorescent dopant, and light emission from the phosphorescent dopant is obtained Although it is a carrier trap type, in any case, it is a condition that the excited state energy of the phosphorescent dopant is lower than the excited state energy of the light emitting host.
The phosphorescent dopant can be appropriately selected from known materials used for the light emitting layer of the organic EL device.
Although the specific example of the compound used as a phosphorescence dopant below is shown, this invention is not limited to these. These compounds are described, for example, in Inorg. Chem. 40, 1704-1711, etc.

  In the present invention, the light emitting dopant contained in the light emitting layer may be one kind, or may contain two or more kinds of light emitting dopants having different light emission maximum wavelengths. When two or more kinds of light emitting dopants are contained, a concentration gradient may be formed in the thickness direction of the light emitting layer for all the light emitting dopants, but only one kind of light emitting dopant may be formed. When the concentration gradient is formed only for one kind of light emitting dopant, it is preferable to form the concentration gradient for the light emitting dopant having the shortest wavelength of the light emission maximum wavelength.

<< Injection layer: electron injection layer, hole injection layer >>
In the organic EL device of the present invention, the injection layer can be provided as necessary. The injection layer includes an electron injection layer and a hole injection layer, and may be present between the anode and the light emitting layer or the hole transport layer and between the cathode and the light emitting layer or the electron transport layer as described above.
The injection layer referred to in the present invention is a layer provided between the electrode and the organic layer in order to lower the driving voltage and improve the light emission luminance. “The organic EL element and its forefront of industrialization (November 30, 1998, NTS) (Published by the company) "Chapter 2 Chapter 2" Electrode Material "(pages 123-166) in detail, there are a hole injection layer and an electron injection layer.
The details of the hole injection layer are described, for example, in JP-A-9-45479, JP-A-9-260062, and JP-A-8-288069. Injection materials include triazole derivatives, oxadiazole derivatives, imidazole derivatives, pyrazoline derivatives and pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives. , Polymers containing silazane derivatives, aniline copolymers, polyarylalkane derivatives, or conductive polymers, preferably polythiophene derivatives, polyaniline derivatives, polypyrrole derivatives, more preferably It is a thiophene derivative.
Details of the electron injection layer are described in, for example, JP-A-6-325871, JP-A-9-17574, and JP-A-10-74586, and specifically, strontium, aluminum and the like are representative. A metal buffer layer, an alkali metal compound buffer layer typified by lithium fluoride, an alkaline earth metal compound buffer layer typified by magnesium fluoride, and an oxide buffer layer typified by aluminum oxide. In the present invention, the buffer layer (injection layer) is desirably a very thin film, and potassium fluoride and sodium fluoride are preferable. The film thickness is about 0.1 nm to 5 μm, preferably 0.1 to 100 nm, more preferably 0.5 to 10 nm, and most preferably 0.5 to 4 nm.

《Hole transport layer》
As the hole transport material constituting the hole transport layer, the same compounds as those applied in the hole injection layer can be used, and further, porphyrin compounds, aromatic tertiary amine compounds, and styryl. It is preferable to use an amine compound, particularly an aromatic tertiary amine compound.
Representative examples of aromatic tertiary amine compounds and styrylamine compounds include N, N, N ', N'-tetraphenyl-4,4'-diaminophenyl; N, N'-diphenyl-N, N'- Bis (3-methylphenyl)-[1,1′-biphenyl] -4,4′-diamine (TPD); 2,2-bis (4-di-p-tolylaminophenyl) propane; 1,1-bis (4-di-p-tolylaminophenyl) cyclohexane; N, N, N ′, N′-tetra-p-tolyl-4,4′-diaminobiphenyl; 1,1-bis (4-di-p-tolyl) Aminophenyl) -4-phenylcyclohexane; bis (4-dimethylamino-2-methylphenyl) phenylmethane; bis (4-di-p-tolylaminophenyl) phenylmethane; N, N'-diphenyl-N, N ' − (4-methoxyphenyl) -4,4'-diaminobiphenyl; N, N, N ', N'-tetraphenyl-4,4'-diaminodiphenyl ether; 4,4'-bis (diphenylamino) quadriphenyl; N, N, N-tri (p-tolyl) amine; 4- (di-p-tolylamino) -4 '-[4- (di-p-tolylamino) styryl] stilbene; 4-N, N-diphenylamino- (2-diphenylvinyl) benzene; 3-methoxy-4′-N, N-diphenylaminostilbenzene; N-phenylcarbazole, and two more described in US Pat. No. 5,061,569 Having a condensed aromatic ring of, for example, 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (NPD), JP-A-4-30 4,4 ', 4 "-tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine in which three triphenylamine units described in Japanese Patent No. 688 are linked in a starburst type ( MTDATA) and the like.
Furthermore, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used. In addition, inorganic compounds such as p-type-Si and p-type-SiC can also be used as the hole injection material and the hole transport material.
JP-A-4-297076, JP-A-2000-196140, JP-A-2001-102175, J. Pat. Appl. Phys. , 95, 5773 (2004), JP-A-11-251067, J. MoI. Huang et. al. It is also possible to use a hole transport material that has a so-called p-type semiconducting property as described in the literature (Applied Physics Letters 80 (2002), p. 139), JP 2003-519432 A. it can.
Although there is no restriction | limiting in particular about the film thickness of a positive hole transport layer, Usually, 5 nm-about 5 micrometers, Preferably it is 5-200 nm. The hole transport layer may have a single layer structure composed of one or more of the above materials.

《Electron transport layer》
The electron transport layer is made of a material having a function of transporting electrons, and in a broad sense, an electron injection layer and a hole blocking layer are also included in the electron transport layer. The electron transport layer can be provided as a single layer or a plurality of layers.
Conventionally, in the case of a single electron transport layer and a plurality of layers, an electron transport material (also serving as a hole blocking material) used for an electron transport layer adjacent to the light emitting layer on the cathode side is injected from the cathode. As long as it has a function of transmitting electrons to the light-emitting layer, any material can be selected and used from among conventionally known compounds. For example, fluorene derivatives, carbazole derivatives, azacarbazole Examples thereof include metal complexes such as derivatives, oxadiazole derivatives, trizole derivatives, silole derivatives, pyridine derivatives, pyrimidine derivatives, and 8-quinolinol derivatives.
In addition, metal-free or metal phthalocyanine, or those having terminal ends substituted with an alkyl group or a sulfonic acid group can be preferably used as the electron transporting material.
Among these, carbazole derivatives, azacarbazole derivatives, pyridine derivatives and the like are preferable in the present invention, and carbazole derivatives and more preferably dibenzofuran compounds according to the present invention.
Although there is no restriction | limiting in particular about the film thickness of an electron carrying layer, Usually, 5 nm-about 5 micrometers, Preferably it is 5-200 nm. The electron transport layer may have a single layer structure composed of one or more of the above materials.
Alternatively, an electron transport layer with high n property doped with impurities as a guest material can be used. Examples thereof include JP-A-4-297076, JP-A-10-270172, JP-A-2000-196140, 2001-102175, J.A. Appl. Phys. 95, 5773 (2004), and the like.

The electron transport layer in the present invention preferably contains an organic alkali metal salt. There are no particular restrictions on the type of organic substance, but formate, acetate, propionic acid, butyrate, valerate, caproate, enanthate, caprylate, oxalate, malonate, succinate Benzoate, phthalate, isophthalate, terephthalate, salicylate, pyruvate, lactate, malate, adipate, mesylate, tosylate, benzenesulfonate , Preferably formate, acetate, propionate, butyrate, valerate, caprate, enanthate, caprylate, oxalate, malonate, succinate, benzoate, more preferably Is preferably an alkali metal salt of an aliphatic carboxylic acid such as formate, acetate, propionate or butyrate, and the aliphatic carboxylic acid preferably has 4 or less carbon atoms. Most preferred is acetate.
The type of alkali metal of the alkali metal salt of the organic substance is not particularly limited, and examples thereof include Na, K, and Cs, preferably K, Cs, and more preferably Cs. Examples of the alkali metal salt of the organic substance include a combination of the organic substance and the alkali metal, preferably, formic acid Li, formic acid K, formic acid Na, formic acid Cs, acetic acid Li, acetic acid K, Na acetate, acetic acid Cs, propionic acid Li, Propionic acid Na, propionic acid K, propionic acid Cs, oxalic acid Li, oxalic acid Na, oxalic acid K, oxalic acid Cs, malonic acid Li, malonic acid Na, malonic acid K, malonic acid Cs, succinic acid Li, succinic acid Na, succinic acid K, succinic acid Cs, benzoic acid Li, benzoic acid Na, benzoic acid K, benzoic acid Cs, more preferably Li acetate, K acetate, Na acetate, Cs acetate, most preferably Cs acetate.
The content of these dope materials is preferably 1.5 to 35% by mass, more preferably 3 to 25% by mass, and most preferably 5 to 15% by mass with respect to the electron transport layer to be added.

"anode"
As the anode constituting the organic EL device, an electrode material made of a metal, an alloy, an electrically conductive compound or a mixture thereof having a high work function (4 eV or more) is preferably used. Specific examples of such an electrode material include metals such as Au, and conductive transparent materials such as CuI, indium tin oxide (ITO), SnO2, and ZnO. Alternatively, an amorphous material such as IDIXO (In2O3-ZnO) that can form a transparent conductive film may be used. For the anode, these electrode materials may be formed into a thin film by a method such as vapor deposition or sputtering, and a desired shape pattern may be formed by a photolithography method, or when pattern accuracy is not so high (about 100 μm or more) A pattern may be formed through a mask having a desired shape at the time of vapor deposition or sputtering of the electrode material. Or when using the substance which can be apply | coated like an organic electroconductivity compound, wet film-forming methods, such as a printing system and a coating system, can also be used. When light emission is extracted from the anode, it is desirable that the transmittance be greater than 10%, and the sheet resistance as the anode is preferably several hundred Ω / □ or less. Further, although the film thickness depends on the material, it is usually in the range of 10 to 1000 nm, preferably in the range of 10 to 200 nm.

"cathode"
As the cathode, a material having a work function (4 eV or less) metal (referred to as an electron injecting metal), an alloy, an electrically conductive compound and a mixture thereof as an electrode material is used. Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al2O3) mixture. , Indium, lithium / aluminum mixtures, rare earth metals and the like. Among these, from the point of durability against electron injection and oxidation, etc., a mixture of an electron injecting metal and a second metal which is a stable metal having a larger work function than this, for example, a magnesium / silver mixture, Magnesium / aluminum mixtures, magnesium / indium mixtures, aluminum / aluminum oxide (Al2O3) mixtures, lithium / aluminum mixtures, aluminum and the like are preferred. The cathode can be produced by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering. The sheet resistance as the cathode is preferably several hundred Ω / □ or less, and the film thickness is usually selected in the range of 10 nm to 5 μm, preferably 50 to 200 nm. In order to transmit the emitted light, if either one of the anode or the cathode of the organic EL element is transparent or translucent, the light emission luminance is improved, which is convenient.
Moreover, after producing the metal with a film thickness of 1 to 20 nm on the cathode, a transparent or translucent cathode can be produced by forming the conductive transparent material mentioned in the description of the anode thereon. By applying this, an organic EL element in which both the anode and the cathode are transmissive can be produced.

《Support substrate》
The support substrate (hereinafter also referred to as a substrate, substrate, substrate, support, etc.) that can be used in the organic EL device of the present invention is not particularly limited in the type of glass, plastic, etc., and is transparent. May be opaque. When extracting light from the support substrate side, the support substrate is preferably transparent. Examples of the transparent support substrate preferably used include glass, quartz, and a transparent resin film. Since the effect of suppressing high-temperature storage stability and chromaticity variation appears greatly in a flexible substrate than a rigid substrate, a particularly preferable support substrate has flexibility that can give flexibility to an organic EL element. Resin film.
Examples of the resin film include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyethylene, polypropylene, cellophane, cellulose diacetate, cellulose triacetate, cellulose acetate butyrate, cellulose acetate propionate (CAP), Cellulose esters such as cellulose acetate phthalate (TAC) and cellulose nitrate or derivatives thereof, polyvinylidene chloride, polyvinyl alcohol, polyethylene vinyl alcohol, syndiotactic polystyrene, polycarbonate, norbornene resin, polymethylpentene, polyether ketone, polyimide , Polyethersulfone (PES), polyphenylene sulfide, polysulfones Cycloolefin resins such as polyetherimide, polyetherketoneimide, polyamide, fluororesin, nylon, polymethylmethacrylate, acrylic or polyarylate, Arton (trade name, manufactured by JSR) or Appel (trade name, manufactured by Mitsui Chemicals) Can be mentioned.

On the surface of the resin film, an inorganic film, an organic film, or a hybrid film of both may be formed. Water vapor permeability (25 ± 0.5 ° C.) measured by a method according to JIS K 7129-1992. , Relative humidity (90 ± 2)% RH) is preferably 0.01 g / (m 2 · 24 h) or less, and further, oxygen permeability measured by a method based on JIS K 7126-1987. Is preferably a high-barrier film having a water vapor transmission rate of 10 −3 g 3 / (m 2 · 24 h · atm) or less and a water vapor transmission rate of 10 −3 g / (m 2 · 24 h) or less. More preferably (m2 · 24h) or less.
As a material for forming the barrier film, any material may be used as long as it has a function of suppressing entry of factors that cause deterioration of the organic EL element such as moisture and oxygen. For example, silicon oxide, silicon dioxide, silicon nitride, or the like is used. Can do. Further, in order to improve the brittleness of the film, it is more preferable to have a laminated structure of these inorganic layers and organic material layers. Although there is no restriction | limiting in particular about the lamination | stacking order of an inorganic layer and an organic layer, It is preferable to laminate | stack both alternately several times.
The method for forming the barrier film is not particularly limited. For example, the vacuum deposition method, the sputtering method, the reactive sputtering method, the molecular beam epitaxy method, the cluster ion beam method, the ion plating method, the plasma polymerization method, the atmospheric pressure plasma. A polymerization method, a plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, or the like can be used, but an atmospheric pressure plasma polymerization method as described in JP-A-2004-68143 is particularly preferable.
Examples of the opaque support substrate include metal plates such as aluminum and stainless steel, films, opaque resin substrates, and ceramic substrates.
In the organic EL device of the present invention, the external extraction efficiency of light emission at room temperature is preferably 1% or more, more preferably 5% or more. Here, the external extraction quantum efficiency (%) = the number of photons emitted to the outside of the organic EL element / the number of electrons sent to the organic EL element × 100.

<Sealing>
As a sealing means applicable to the organic EL element of the present invention, for example, a method of adhering a sealing member, an electrode, and a support substrate with an adhesive can be mentioned.
As a sealing member, it should just be arrange | positioned so that the display area | region of an organic EL element may be covered, and concave plate shape or flat plate shape may be sufficient. Further, transparency and electrical insulation are not particularly limited.
Specific examples include a glass plate, a polymer plate / film, and a metal plate / film. Examples of the glass plate include soda-lime glass, barium / strontium-containing glass, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass, and quartz. Examples of the polymer plate include polycarbonate, acrylic, polyethylene terephthalate, polyether sulfide, and polysulfone. Examples of the metal plate include those made of one or more metals or alloys selected from the group consisting of stainless steel, iron, copper, aluminum, magnesium, nickel, zinc, chromium, titanium, molybdenum, silicone, germanium, and tantalum.
In the present invention, a polymer film and a metal film can be preferably used because the element can be thinned. Further, the polymer film has an oxygen permeability measured by a method according to JIS K 7126-1987 of 1 × 10 −3 cm 3 / (m 2 · 24 h · atm) or less and a method according to JIS K 7129-1992. The measured water vapor permeability (25 ± 0.5 ° C., relative humidity (90 ± 2)% RH) is preferably 1 × 10 −3 g / (m 2 · 24 h) or less.
For processing the sealing member into a concave shape, sandblasting, chemical etching, or the like is used.

Specific examples of the adhesive include photo-curing and thermosetting adhesives having reactive vinyl groups such as acrylic acid oligomers and methacrylic acid oligomers, and moisture curing adhesives such as 2-cyanoacrylates. Can be mentioned. Moreover, heat | fever and chemical curing types (two-component mixing), such as an epoxy type, can be mentioned. Moreover, hot-melt type polyamide, polyester, and polyolefin can be mentioned. Moreover, a cationic curing type ultraviolet curing epoxy resin adhesive can be mentioned.
In addition, since an organic EL element may deteriorate by heat processing, what can be adhesive-hardened from room temperature to 80 degreeC is preferable. Further, a desiccant may be dispersed in the adhesive. Application | coating of the adhesive agent to a sealing part may use commercially available dispenser, and may print like screen printing.
In addition, it is also preferable that the electrode and the organic layer are coated on the outside of the electrode facing the support substrate with the organic layer interposed therebetween, and an inorganic or organic layer is formed in contact with the support substrate to form a sealing film. . In this case, the material for forming the film may be any material that has a function of suppressing intrusion of elements that cause deterioration of elements such as moisture and oxygen. For example, silicon oxide, silicon dioxide, silicon nitride, or the like may be used. it can. Further, in order to improve the brittleness of the film, it is preferable to have a laminated structure of these inorganic layers and layers made of organic materials. The method for forming these films is not particularly limited. For example, vacuum deposition, sputtering, reactive sputtering, molecular beam epitaxy, cluster-ion beam method, ion plating method, plasma polymerization method, atmospheric pressure plasma A polymerization method, a plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, or the like can be used.

In order to form a gas phase and a liquid phase in the gap between the sealing member and the display area of the organic EL element, an inert gas such as nitrogen or argon, an inert gas such as fluorinated hydrocarbon or silicon oil is used. It is preferable to inject a liquid. A vacuum is also possible. Moreover, a hygroscopic compound can also be enclosed inside.
Examples of the hygroscopic compound include metal oxides (for example, sodium oxide, potassium oxide, calcium oxide, barium oxide, magnesium oxide, aluminum oxide) and sulfates (for example, sodium sulfate, calcium sulfate, magnesium sulfate, cobalt sulfate). Etc.), metal halides (eg calcium chloride, magnesium chloride, cesium fluoride, tantalum fluoride, cerium bromide, magnesium bromide, barium iodide, magnesium iodide etc.), perchloric acids (eg perchloric acid) Barium, magnesium perchlorate, and the like), and anhydrous salts are preferably used in sulfates, metal halides, and perchloric acids.
Sealing includes casing type sealing (can sealing) and close contact type sealing (solid sealing), but solid sealing is preferable from the viewpoint of thinning. Moreover, when producing a flexible organic EL element, since sealing is also required for the sealing member, solid sealing is preferable.

《Protective film, protective plate》
In order to increase the mechanical strength of the organic EL element, a protective film or a protective plate may be provided outside the sealing film on the side facing the support substrate with the organic layer interposed therebetween or on the outer side of the sealing film. In particular, when sealing is performed with a sealing film, the mechanical strength is not necessarily high, and thus it is preferable to provide such a protective film and a protective plate. As a material that can be used for this, the same glass plate, polymer plate / film, metal plate / film, etc. used for the sealing can be used. Is preferably used.
In the present invention, it is preferable to have a light extraction member between the flexible support substrate and the anode, or at any location on the light emission side from the flexible support substrate.
Examples of the light extraction member include a prism sheet, a lens sheet, and a diffusion sheet. Further, a diffraction grating or a diffusion structure introduced into an interface or any medium that causes total reflection can be used.
In general, in an organic electroluminescence element that emits light from a substrate, a part of the light emitted from the light emitting layer causes total reflection at the interface between the substrate and air, causing a problem of loss of light. In order to solve this problem, prismatic or lens-like processing is applied to the surface of the substrate, or prism sheets, lens sheets, and diffusion sheets are affixed to the surface of the substrate, thereby suppressing total reflection and light extraction efficiency. To improve.
In order to increase the light extraction efficiency, a method of introducing a diffraction grating or a method of introducing a diffusion structure in an interface or any medium that causes total reflection is known.

<< Method for Manufacturing Organic EL Element >>
As an example of the method for producing an organic EL device of the present invention, a method for producing an organic EL device comprising an anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode will be described.

  First, on a suitable substrate (support substrate), a thin film made of a desired electrode material, for example, an anode material is formed by a thin film forming method such as vapor deposition or sputtering so that the film thickness is 1 μm or less, preferably 10 to 200 nm. An anode is produced by forming the anode.

Next, organic layers such as a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, and an electron injection layer, which are organic EL element materials, are formed thereon.
As a method for forming each of these layers, a wet process by a die coating method is preferable for the light emitting layer as described above, but a wet process (for example, a spin coating method, a casting method, a die coating method, a blade coating method) is also performed for other organic layers. , A roll coating method, an ink jet method, a printing method, a spray coating method, a curtain coating method, an LB method (Langmuir Brodgett method and the like can be mentioned), and from the viewpoint of productivity, a light emitting layer. Similarly, formation by a die coating method is more preferable.
Examples of the liquid medium for dissolving or dispersing the organic EL material according to the present invention include ketones such as methyl ethyl ketone and cyclohexanone, fatty acid esters such as ethyl acetate and butyl acetate, halogenated hydrocarbons such as dichlorobenzene, toluene, Aromatic hydrocarbons such as xylene, mesitylene, and cyclohexylbenzene, aliphatic hydrocarbons such as cyclohexane, decalin, and dodecane, and organic solvents such as dimethylformamide (DMF) and dimethylsulfoxide (DMSO) can be used. Moreover, as a dispersion method, it can disperse | distribute by dispersion methods, such as an ultrasonic wave, high shear force dispersion | distribution, and media dispersion | distribution.

  After these layers are formed, a thin film made of a cathode material is formed thereon by 1 μm or less, preferably by a method such as vapor deposition or sputtering so that the film thickness is in the range of 50 nm to 200 nm. By providing, a desired organic EL element can be obtained.

In the present invention, it is preferable to heat-treat the organic EL device in the range of 40 to 200 ° C. after providing the cathode because the effect of suppressing high-temperature storage stability and chromaticity variation is remarkable. When using a resin film, 40-150 degreeC, especially 40-120 degreeC are preferable. The heat treatment time is preferably in the range of 10 seconds to 30 minutes.
After the heat treatment, an organic EL element is produced by closely sealing or adhering the sealing member, the electrode, and the support substrate with an adhesive.

<Application>
The organic EL element of the present invention can be used as a display device, a display, and various light emission sources. Examples of light sources include home lighting, interior lighting, clock and liquid crystal backlights, billboard advertisements, traffic lights, light sources for optical storage media, light sources for electrophotographic copying machines, light sources for optical communication processors, and light sources for optical sensors. Furthermore, it can be used in a wide range of applications such as general household appliances that require a display device, but it can be used effectively as a backlight for a liquid crystal display device combined with a color filter, and as a light source for illumination. it can.
In the organic EL element of the present invention, patterning may be performed by a metal mask, an ink jet printing method, or the like as needed during film formation. In the case of patterning, only the electrode may be patterned, the electrode and the light emitting layer may be patterned, or the entire layer of the element may be patterned. In the fabrication of the element, a conventionally known method is used. Can do.

Hereinafter, the present invention will be specifically described with reference to Examples 1 to 4, but the present invention is not limited thereto.
In Examples 1 to 4, “part” or “%” is used, but “part by mass” or “% by mass” is indicated unless otherwise specified.

<Production of sample>
(1) Preparation of sample 101 After patterning on a substrate (NH45 made of NH Techno Glass) with 150 nm of ITO (indium tin oxide) formed on a 150 mm × 150 mm × 1.1 mm glass substrate as an anode, this ITO The substrate provided with the transparent electrode was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and subjected to UV ozone cleaning for 5 minutes. A solution obtained by diluting poly (3,4-ethylenedioxythiophene) -polystyrene sulfonate (PEDOT / PSS, Bayer, Baytron P Al 4083) to 70% with pure water on this substrate was spin-coated at 3000 rpm for 30 seconds. After film formation by the method, the film was dried at 200 ° C. for 1 hour to provide a first hole transport layer having a thickness of 30 nm.
This substrate was transferred to a nitrogen atmosphere using nitrogen gas (grade G1), and a solution obtained by dissolving 0.5% of the HT-1 compound (Mw = 80,000) as the hole transport material in chlorobenzene was obtained at 1500 rpm. After forming the film by spin coating in 30 seconds, the film was held at 160 ° C. for 30 minutes to form a second hole transport layer having a thickness of 30 nm.

Next, the following light emitting layer composition 1 was injected and injected using an inkjet head (manufactured by Epson; MJ800C) so that the coating liquid film thickness was 5.3 μm. This substrate was subjected to a drying treatment for 10 minutes in a 120 ° C. drying box to form a light emitting layer (first layer) having a thickness of 40 nm.
(Light emitting layer composition 1)
Host (HA) 0.69 parts by mass Blue dopant (D-66) 0.30 parts by mass Green dopant (D-67) 0.005 parts by mass Red dopant (D-80) 0.005 parts by mass Isopropyl acetate 100 Parts by mass

Furthermore, the following light emitting layer composition 2 was injected and injected using an inkjet head (manufactured by Epson; MJ800C) so that the coating liquid film thickness was 5.3 μm. This substrate was subjected to a drying treatment for 10 minutes in a 120 ° C. drying box to obtain a 40 nm light emitting layer (second layer).
(Light emitting layer composition 2)
Host (HA) 0.89 parts by weight Blue dopant (D-66) 0.10 parts by weight Green dopant (D-67) 0.005 parts by weight Red dopant (D-80) 0.005 parts by weight Isopropyl acetate 100 Parts by mass

Subsequently, a solution of 30 mg of ET-1 compound dissolved in 4 ml of tetrafluoropropanol (TFPO) was formed by spin coating at 1500 rpm for 30 seconds, and then kept at 120 ° C. for 30 minutes, It was set as the electron carrying layer.
Subsequently, the substrate was attached to a vacuum deposition apparatus without being exposed to the atmosphere. A molybdenum resistance heating boat containing sodium fluoride and potassium fluoride is attached to a vacuum deposition apparatus, and the vacuum chamber is depressurized to 4 × 10 ⁻⁵ Pa. A thin film having a thickness of 1 nm is formed on the electron transport layer at a rate of 0.02 nm / second with sodium fluoride, and then an electron with a thickness of 1.5 nm on the sodium fluoride at a rate of 0.02 nm / second in the same manner. An injection layer was formed.
Subsequently, 100 nm of aluminum was deposited to form a cathode, and “Sample 101 (organic EL element)” was produced.

(2) Production of Sample 102 In production of the sample 101, the first and second layers of the light emitting layer were produced by the following method. Otherwise, “Sample 102 (organic EL element)” was prepared in the same manner as Sample 101.
(2.1) First layer of light-emitting layer Using a die coater (manufactured by Chugai Furnace Co., Ltd.), the light-emitting layer composition 1 is coated at a coating speed of 1 m / min so that the coating film thickness becomes 5.3 μm. After discharging and 5 seconds after application, the film was dried by blowing nitrogen at 0.5 m / second, and then kept at 120 ° C. for 30 minutes to form a first light emitting layer having a thickness of 40 nm.
(2.2) Second layer of light-emitting layer The light-emitting layer composition 2 was discharged using a die coater so that the coating liquid film thickness became 5.3 μm at a coating speed of 1 m / min, and 5 seconds after coating. After drying with nitrogen blowing at 0.5 m / second, the mixture was kept at 120 ° C. for 30 minutes to form a second light emitting layer having a thickness of 40 nm.

(3) Preparation of Samples 103 and 104 In the preparation of Sample 102, the concentration ratio of the host material (HA) and the dopant (D-66) in the light-emitting layer composition 1 and the light-emitting layer composition 2 is shown in Table 1. It was changed as follows.
Other than that was carried out similarly to the sample 102, and produced "sample 103,104 (organic EL element)".

(4) Measurement of dopant concentration distribution The concentration distribution of the luminescent dopant contained in the luminescent layers of the samples 101 to 104 obtained as described above was analyzed by TOF-SIMS (time-of-flight secondary ion mass spectrometry). The Ir distribution in the film thickness direction was measured.
The obtained results are shown in Table 1. In Samples 101 to 103, the anode side has the highest dopant concentration and the dopant concentration continuously decreases toward the cathode side, whereas in Sample 104, the dopant concentration decreases. The concentration distribution was almost uniform from the anode side to the cathode side.

<Evaluation of sample>
About the produced sample, the external extraction quantum efficiency, the light emission lifetime, and the light emission in-plane luminance unevenness were evaluated as follows.
(1) External extraction quantum efficiency The external extraction quantum efficiency (%) when a ^2.5 mA / cm ² constant current was applied to the prepared sample was measured. A spectral radiance meter CS-1000 (manufactured by Konica Minolta Sensing) was used for the measurement.
The quantum efficiency was expressed as a relative value with respect to the measured value of the sample 101 as 100.

(2) Luminous lifetime A current that gives a front luminance of 1000 cd / m ² was applied to the prepared sample and continuously driven. The time required for the front luminance to reach the initial half value (500 cd / m ² ) (light emission lifetime) was determined. For the measurement, a spectral radiance meter CS-1000 (manufactured by Konica Minolta Sensing) was used.
The light emission lifetime was expressed as a relative value with respect to the measured value of the sample 101 as 100.

(3) Luminance unevenness The luminance distribution in the light-emitting surface when a ^2.5 mA / cm ² constant current was applied to the prepared sample was measured with Prometric (manufactured by Cybernet System).
The luminance distribution is represented by the standard deviation of each luminance when the light emitting surface is equally divided into 40. A lower numerical value indicates less luminance unevenness.

  Table 1 shows the results of quantum efficiency, emission lifetime, and luminance unevenness obtained as described above.

(4) Summary As is clear from the results shown in Table 1, in Samples 102 and 103 in which the light emitting layer was applied by a die coating method and a dopant concentration gradient was formed in the thickness direction of the light emitting layer, quantum efficiency and light emission lifetime characteristics were obtained. It can be seen that it is excellent as a light emitting device with little luminance unevenness in the light emitting area.

<Production of sample>
In the formation of the second light emitting layer of the sample 102 of the sample 102 in Example 1, “Samples 201 to 203 (organic EL element)” were produced in the same manner except that the coating speed was set to the value shown in Table 2 and the coating was performed by die coating. . Further, the concentration distribution of the light-emitting dopant contained in the light-emitting layers of Samples 201 to 203 was measured by TOF-SIMS as in Example 1.

<Evaluation of sample>
(1) Contents of evaluation About the samples 201-203 produced as mentioned above, the external extraction quantum efficiency, the light emission lifetime, and the light emission in-plane brightness nonuniformity were evaluated similarly to Example 1.
The external extraction quantum efficiency and the light emission lifetime were expressed as relative values with respect to the measurement value of the sample 102 of Example 1 as 100. The results are shown in Table 2.

(2) Summary As is apparent from the results shown in Table 2, samples 202 and 203 (including sample 102) in which the concentration gradient of the dopant was formed by applying the coating speed of the second light emitting layer at 1 m / min or more. ) Shows that the external extraction quantum efficiency and the light emission lifetime are also good, and the luminance unevenness within the light emission area is more excellent.

<Production of sample>
(1) Production of Sample 301 In the formation of the second light-emitting layer of sample 102 in Example 1, the light-emitting layer composition 2 of Example 1 was coated at a coating speed of 1 m / min using a die coater. “Sample 301 (Organic EL device)” in the same manner except that the sample was discharged to 5.3 μm, dried one second after application with nitrogen blow at 0.5 m / second and then kept at 120 ° C. for 30 minutes. Was made.

(2) Production of Samples 302 and 303 In the formation of the second light emitting layer of Sample 102 of Example 1, the light emitting layer composition 2 of Example 1 was applied at a coating speed of 1 m / min using a die coater. “Samples 302 and 303 (organic EL elements)” were produced in the same manner except that the film was discharged to a thickness of 5.3 μm, dried with a mid-wavelength infrared heater after application, and held at 120 ° C. for 30 minutes. .
The drying of the medium wavelength infrared heater was performed under an output condition such that the substrate surface temperature was 100 ° C., and the time from application to drying of the medium wavelength infrared heater was set to the time shown in Table 3.

(3) Production of Sample 304 In the formation of the second light emitting layer of sample 102 in Example 1, the light emitting layer composition 2 of Example 1 was applied at a coating speed of 1 m / min using a die coater. The sample 304 (organic EL element) was produced in the same manner except that the sample was discharged so as to have a thickness of 5.3 μm and then naturally dried.

  As described above, the concentration distribution of the light-emitting dopant contained in the light-emitting layers of Samples 301 to 304 was measured by TOF-SIMS as in Example 1.

<Evaluation of sample>
(1) Evaluation content The produced samples 301 to 304 were evaluated for external extraction quantum efficiency, light emission lifetime, and light emission in-plane luminance unevenness in the same manner as in Example 1.
The external extraction quantum efficiency and the light emission lifetime were expressed as relative values with respect to the measurement value of the sample 102 of Example 1 as 100. The results are shown in Table 3.

(2) Summary As is apparent from the results shown in Table 3, a dopant concentration gradient is formed by blowing the coating liquid within 5 seconds or heating the coating liquid within 5 seconds immediately after the application of the second layer of the light emitting layer by die coating. It can be seen that the samples 301 to 303 (including the sample 102) have better external extraction quantum efficiency and light emission lifetime.

<Production of sample>
In the formation of the second layer of the light emitting layer of the sample 102 of Example 1, the “samples 401 to 405 (organic EL element) ".
Moreover, the density | concentration distribution of the light emission dopant contained in the light emitting layer of the samples 401-405 was measured by TOF-SIMS like Example 1. FIG.

<Evaluation of sample>
(1) Contents of evaluation About the produced samples 401-405, the external extraction quantum efficiency, the light emission lifetime, and the light emission in-plane brightness nonuniformity were evaluated similarly to Example 1.
The external extraction quantum efficiency and the light emission lifetime were expressed as relative values with respect to the measurement value of the sample 102 of Example 1 as 100. The results are shown in Table 4.

(2) Summary As is apparent from the results shown in Table 4, samples 403 to 405 (including sample 102) whose coating liquid film thickness by die coating application of the second layer of the light emitting layer is smaller than 10 μm are external extraction quantum efficiencies. It can be seen that the light emission life is also good and the luminance unevenness within the light emission area is more excellent.

Claims (6)

In the method for producing an organic electroluminescence device, an anode, a cathode and a light emitting layer are formed on a substrate, the light emitting layer is interposed between the anode and the cathode, and the light emitting host and the light emitting dopant are contained.
A step of forming the light emitting layer by laminating two or more kinds of coating liquids having different dopant concentrations by a die coating method;
In the step of forming the light emitting layer, a dopant concentration gradient is formed in the thickness direction of the light emitting layer. In the manufacturing method of the organic electroluminescent element of Claim 1,
In the step of forming the light emitting layer, among two or more kinds of coating liquids having different dopant concentrations, the dopant concentration of the coating liquid coated on the anode side is the dopant concentration of the coating liquid coated on the cathode side. The manufacturing method of the organic electroluminescent element characterized by making it higher. In the manufacturing method of the organic electroluminescent element of Claim 1 or Claim 2,
In the step of forming the light emitting layer, two or more kinds of coating liquids having different dopant concentrations are separately ejected for each layer, and the second and subsequent coating liquids are coated at a coating speed of 1 m / min or more. A method for producing an organic electroluminescence device characterized in that: In the manufacturing method of the organic electroluminescent element as described in any one of Claims 1-3,
In the step of forming the light emitting layer, whether two or more kinds of coating liquids having different dopant concentrations are discharged separately for each layer and blown to the second and subsequent coating liquids within 5 seconds immediately after coating. Or the manufacturing method of the organic electroluminescent element characterized by heating the coating liquid within 5 second immediately after application | coating. In the manufacturing method of the organic electroluminescent element as described in any one of Claims 1-4,
In the step of forming the light emitting layer, two or more kinds of coating liquids having different dopant concentrations are discharged separately for each layer, and the film thickness of the coating liquid after the second layer is set to 1 to 10 μm. A method for producing an organic electroluminescent element.   The organic electroluminescent element manufactured with the manufacturing method as described in any one of Claims 1-5.