JP2011029118A - Method of manufacturing organic el element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing an organic EL element, which can be manufactured simply and easily and can improve element characteristics. <P>SOLUTION: The method of manufacturing an organic EL element, in which the organic EL element having a pair of electrodes and a luminous layer installed between the electrodes is fabricated on a supporting substrate, includes a step in which a thin film including a wire and resin showing conductivity is formed on the supporting substrate and one electrode toward the supporting substrate out of the pair of electrodes is formed, a step in which ink containing a material to become the luminous layer is coated and formed on the one of electrodes and the luminous layer is formed by solidifying this, and a step in which the other electrode out of the pair of electrodes is formed in this order. After forming one of the electrodes and until the step of forming the luminous layer is completed, the oxygen concentration and moisture concentration in the atmosphere surrounding the supporting substrate are maintained at less than the atmospheric concentrations in volume ratio. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a light emitting device.

  An organic EL (electroluminescence) element is a light-emitting element using an organic material as a light-emitting material, and includes a pair of electrodes including an anode and a cathode, and a light-emitting layer provided between the electrodes. When a voltage is applied to the organic EL element, holes are injected from the anode and electrons are injected from the cathode, and light is emitted by combining these holes and electrons in the light emitting layer.

  An organic EL element has an advantage in a manufacturing process in which a light emitting layer can be formed using a coating method having a relatively simple process as a film forming method (see, for example, Patent Document 1).

JP 2007-265680 A

  In the organic EL element, light emitted from the light emitting layer is emitted to the outside through the electrode, and therefore one electrode of the pair of electrodes is configured by an electrode exhibiting light transmittance. At present, a thin film made of indium tin oxide (abbreviated as ITO) is often used as an electrode exhibiting light transmittance from the viewpoint of characteristics as an electrode having relatively high light transmittance and conductivity. Yes. However, since this ITO is formed by the sputtering method, the process is complicated as compared with the coating method. In order to simplify the manufacturing process, the present inventors have studied to form a conductive thin film containing conductive wires and resin as an electrode replacing the ITO thin film. Furthermore, in the manufacturing method of an element when such a conductive thin film is adopted as an electrode, a method capable of improving element characteristics is being sought.

  Accordingly, an object of the present invention is to provide a method for manufacturing an organic EL element that can be easily manufactured and can improve element characteristics.

The present invention is a method for producing an organic EL element, which comprises producing an organic EL element comprising a pair of electrodes and a light emitting layer provided between the electrodes on a support substrate,
Forming a thin film containing a conductive wire and resin on the support substrate to form one of the pair of electrodes closer to the support substrate; and
A step of forming a light emitting layer by coating and forming an ink containing a material to be a light emitting layer on the one electrode, and further solidifying it;
Forming the other electrode of the pair of electrodes in this order,
The oxygen concentration and water concentration in the atmosphere around the support substrate are each kept below the atmospheric concentration by volume until the step of forming the light emitting layer is completed after forming the one electrode. The present invention relates to a method for manufacturing an organic EL element.

In the present invention, the step of forming an adjacent layer provided between and in contact with the light emitting layer between the one electrode and the light emitting layer is performed after the step of forming one electrode and before the step of forming the light emitting layer. Further including
In the step of forming the adjacent layer, an ink including a material that becomes the adjacent layer is applied on the one electrode, and the adjacent layer is formed by solidifying the ink. It relates to a manufacturing method.

  According to the present invention, after the formation of the one electrode, until the step of forming the light emitting layer is completed, the oxygen concentration and the moisture concentration in the atmosphere around the support substrate are each kept at 1000 ppm or less by volume ratio. The present invention relates to a manufacturing method of a characteristic organic EL element.

  The present invention relates to a method for producing an organic electroluminescent element, wherein in the step of forming the light emitting layer, the light emitting layer is solidified by heating at 50 ° C. to 250 ° C.

  In the present invention, in the step of forming the one electrode, the refractive index is 1.8 or less, the absolute value of the difference in refractive index from the support substrate is less than 0.4, and exhibits light transmittance. The present invention relates to a method for manufacturing an organic EL element, wherein the one electrode is formed.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the organic EL element which an element characteristic improves with a simple manufacturing method can be provided.

It is a side view which shows typically the organic EL element 1 of this embodiment.

  The organic EL element produced on a support substrate by the manufacturing method of the organic EL element of this embodiment includes a pair of electrodes and a light emitting layer provided between the electrodes. The organic EL element includes an anode and a cathode as a pair of electrodes. The organic EL element may further include a predetermined layer different from the light emitting layer between the pair of electrodes as necessary in consideration of required characteristics and process simplicity, and two or more light emitting layers. May be provided between a pair of electrodes.

  In the present embodiment, one of the pair of electrodes closer to the support substrate is made of a thin film containing conductive wires and resin (hereinafter sometimes referred to as a conductive resin thin film).

  Hereinafter, a conductive resin thin film functioning as an anode is provided as one of the electrodes near the support substrate, and an organic layer having one adjacent layer between the conductive resin thin film and the light emitting layer is provided. The EL element 1 will be described as an embodiment of the present invention. This adjacent layer is provided in contact with the light emitting layer and functions as, for example, a hole injection layer or a hole transport layer described later.

  FIG. 1 is a side view schematically showing an organic EL element 1 of the present embodiment. The organic EL element 1 of the present embodiment is provided on the support substrate 2. The organic EL element 1 is produced by laminating one electrode 3, the adjacent layer 4, the light emitting layer 5, and the other electrode 6 in this order from the support substrate 2 side. Here, of the pair of electrodes, one electrode 3 disposed closer to the support substrate 2 corresponds to a conductive resin thin film.

  In the present embodiment, one electrode 3 is provided as an anode, and the other electrode 6 is provided as a cathode. In another embodiment, an organic EL element having one electrode 3 as a cathode and the other electrode 6 as an anode may be configured.

  Hereinafter, the manufacturing method of the organic EL element of this embodiment is demonstrated. The manufacturing method of the organic EL element of this embodiment forms one electrode close to the support substrate of the pair of electrodes by forming a thin film containing conductive wires and resin on the support substrate. A step of forming a light emitting layer by coating and forming an ink containing a material to be a light emitting layer on the one electrode, and further solidifying the ink; and forming the other electrode of the pair of electrodes Steps in this order, and after the formation of the one electrode, until the step of forming the light emitting layer is completed, the oxygen concentration and the moisture concentration in the atmosphere around the support substrate are each expressed as an atmospheric concentration by volume ratio. Keep it below.

  In this embodiment, an adjacent layer adjacent to the light emitting layer is provided as a preferred embodiment. Therefore, the adjacent layer is formed after the step of forming one electrode and before the step of forming the light emitting layer. In the step of forming the adjacent layer, an ink containing a material to be the adjacent layer is applied on the one electrode, and the adjacent layer is formed by solidifying the ink.

<One electrode forming step>
In this step, a thin film containing conductive wires and resin is formed on the support substrate 2 as one electrode. The conductive resin thin film includes an electrode film main body made of a resin and a wire exhibiting conductivity dispersed in the electrode film main body. Such a conductive resin thin film can be formed by, for example, a coating method.

  As the electrode film body, one having a high light transmittance in the visible light region is preferably used, and may further contain an inorganic polymer, an inorganic-organic hybrid compound, or the like in addition to the resin. As the electrode film body, a conductive resin is preferably used. Thus, in addition to the wire which has electroconductivity, the electrical resistance of a conductive resin thin film can be lowered | hung by using the electrode film main body which has electroconductivity. The film thickness of the conductive resin thin film is appropriately set depending on the electrical resistance, the visible light transmittance, and the like, and is, for example, 0.02 μm to 2 μm, and preferably 0.02 to 1 μm.

  The diameter of the wire is preferably smaller, for example, 400 nm or less, preferably 200 nm or less, and more preferably 100 nm or less. The wire disposed in the electrode film body diffracts or scatters the light passing through the electrode, so that the haze value is increased and the light transmittance is reduced, but it is about the wavelength of visible light or smaller than the wavelength of visible light. By using a wire having a diameter, a haze value with respect to visible light can be suppressed to a low level and a decrease in light transmittance can be suppressed. Moreover, since resistance will become high if the diameter of a wire is too small, 10 nm or more is preferable.

  One wire or a plurality of wires may be disposed in a dispersed manner in the electrode film main body, and it is preferable that a network structure is formed in the electrode film main body. For example, in the electrode film main body, it is preferable that one or a plurality of wires are arranged in an intricately intertwined manner throughout the electrode film main body to form a network structure. For example, a structure in which one wire is intertwined in a complicated manner or a plurality of wires are arranged in contact with each other may be spread in two or three dimensions to form a network structure. The volume resistivity of the conductive resin thin film can be lowered by the wires constituting the network structure.

  The wire may be, for example, curved or needle-shaped, and may be tubular. An electrode having a low volume resistivity can be realized by forming a network structure in which curved and needle-shaped wires come into contact with each other.

(Wire)
The wire is preferably made of a metal or carbon nanotube with low electrical resistance. Examples of the wire material include Ag, Au, Cu, Al, and alloys thereof. For example, the wire is obtained by the method by NRJana, L. Gearheart and CJMurphy (Chm. Commun., 2001, p617-p618), the method by C. Ducamp-Sanguesa, R. Herrera-Urbina, and M. Figlarz, etc. (J. Solid State Chem., Vol. 100, 1992, p272-p280). For example, a silver nanowire (major axis average length 1 μm, minor axis average length 10 nm) whose surface is protected with an amino group-containing polymer dispersant (product name “Solsperse 24000SC” manufactured by IC Japan Ltd.) Can be used as a wire.

  Examples of the carbon nanotube used as the linear conductor include single-walled carbon nanotubes, double-walled carbon nanotubes, multi-walled carbon nanotubes, and rope-like carbon nanotubes, and those having high conductivity are preferable.

  As a method for forming a conductive resin thin film, for example, a method of dispersing a wire in a resin by kneading the wire into a resin, or forming a dispersion liquid in which a wire and a resin are dispersed in a dispersion medium by a predetermined coating method. And a method of coating the surface of a film made of resin with a wire and dispersing the wire in the film. In addition, you may add various additives, such as surfactant and antioxidant, to a dispersion liquid as needed. The type of resin is appropriately selected according to the characteristics required for the electrode, such as refractive index, light transmittance, and electrical resistance.

  In addition, the weight ratio of the wire in the conductive resin thin film affects the electrical resistance, haze value, translucency, and the like of the electrode, and thus is appropriately set according to the characteristics required for the conductive resin thin film.

  The conductive resin thin film can be obtained, for example, by coating a film of a dispersion in which a conductive wire is dispersed in a dispersion medium by a predetermined coating method and further curing the film.

  The dispersion is prepared by dispersing a wire and a resin in a dispersion medium. Any dispersion medium may be used as long as it dissolves or disperses the resin, for example, a chlorine solvent such as chloroform, methylene chloride or dichloroethane, an ether solvent such as tetrahydrofuran, an aromatic hydrocarbon solvent such as toluene or xylene, acetone, or the like. And ketone solvents such as methyl ethyl ketone, and ester solvents such as ethyl acetate, butyl acetate, and ethyl cellosolve acetate.

  Carbon nanotubes may aggregate in the dispersion medium, and the transmittance of one of the electrodes formed using the dispersion liquid in which the carbon nanotubes are aggregated may be reduced. Therefore, when carbon nanotubes are used as the linear conductor, it is particularly preferable to use a dispersion medium capable of uniformly dispersing the carbon nanotubes. Examples of such a dispersion medium include carboxylic acids such as formic acid and acetic acid. Compound: Epoxy compound such as propylene oxide, 1,2-epoxybutane, (cis, trans) 2,3-epoxybutane; n-propylamine, iso-propylamine, N-ethylmethylamine, n-butylamine, sec- Primary amine compounds such as butylamine, iso-butylamine, tert-butylamine, n-amylamine, tert-amylamine, isoamylamine, hexylamine; diethylamine, N-methylpropylamine, N-methylisopropylamine, N-ethylisopropylamine, 2-methylbutylamine, 2-methylbutylamine, N-methyl-tert-butylamine, diisopropylamine, dipropylamine, N-ethylbutylamine, N-methylpentylamine, N-tert-butylisopropylamine, N-propylbutylamine, etc. N, N-diethylmethylamine, 1,2-dimethylpropylamine, 1,3-dimethylbutylamine, 3,3-dimethylbutylamine, triethylamine, N-methyldiisopropylamine, N, N-diisopropylethylamine, N -Isopropyl-N-methyl-tert-butylamine, triisopropylamine, dimethylformamide (DMF), diethylformamide, dimethylacetamide (DMAc), N-methylpyrrolidone (NMP), etc. A tertiary amine compound is mentioned, N-methylpyrrolidone (NMP) is preferable.

  Further, as described above, a surfactant may be further added to the dispersion. Examples of such a surfactant include polyhydric alcohol and fatty acid ester-based or polyoxyethylene-based polyoxyethylene-based surfactant. Alternatively, nonionic surface activity having both systems can be raised, and polyoxyethylene-based nonionic surface activity is preferable. Examples of polyoxyethylene surfactants include fatty acid polyoxyethylene ethers, higher alcohol polyoxyethylene ethers, alkyl phenols polyoxyethylene ethers, sorbitan ester polyoxyethylene ethers, castors Examples include oil polyoxyethylene ether, polyoxypropylene polyoxyethylene ether, and fatty acid alkylol amide. Examples of polyhydric alcohol and fatty acid ester surfactants include monoglycerite surfactants, sorbitol surfactants, saltabine surfactants, and sugar ester surfactants.

  The carbon nanotubes can be uniformly dispersed in the dispersion liquid, for example, by dispersing the carbon nanotubes in the dispersion liquid while performing ultrasonic treatment. For example, by adding the above-described surfactant, the carbon nanotubes can be prevented from aggregating after being dispersed in the dispersion, and the dispersion state in the dispersion can be maintained.

  Examples of the resin include low density or high density polyethylene, ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-hexene copolymer, ethylene-octene copolymer, ethylene-norbornene copolymer, ethylene- Polyolefin resins such as dimethanooctahydronaphthalene copolymer, polypropylene, ethylene-vinyl acetate copolymer, ethylene-methyl methacrylate copolymer, ionomer resin; polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate Nylon-6, nylon-6,6, metaxylenediamine-adipic acid condensation polymer; amide resin such as polymethylmethacrylamide; acrylic resin such as polymethylmethacrylate; polystyrene, Styrene-acrylonitrile resins such as tylene-acrylonitrile copolymer, styrene-acrylonitrile butadiene copolymer, polyacrylonitrile; hydrophobized cellulose resins such as cellulose triacetate and cellulose diacetate; polyvinyl chloride, polyvinylidene chloride, polyfluoride Halogen-containing resins such as vinylidene and polytetrafluoroethylene; hydrogen-bonding resins such as polyvinyl alcohol, ethylene-vinyl alcohol copolymer and cellulose derivatives; polycarbonate resins, polysulfone resins, polyethersulfone resins, polyetheretherketone resins, Examples include engineering plastic resins such as polyphenylene oxide resin, polymethylene oxide resin, polyarylate resin, and liquid crystal resin.

  As the resin, a resin having conductivity is preferably used. Examples of the resin having conductivity include polyaniline and polythiophene derivatives. For example, a poly (ethylenedioxythiophene) / polystyrene sulfonic acid solution having a refractive index of 1.7 (trade name “BaytronP” manufactured by Starck Co., Ltd.) having a refractive index of 1.7 can be used as the conductive resin.

  The refractive index of the conductive resin thin film is mainly determined by the refractive index of the electrode film body. Since the refractive index of the electrode film main body is mainly determined by the type of resin used, a conductive resin thin film having an intended refractive index can be easily obtained by appropriately selecting the resin used. For example, when the conductive resin thin film is provided in contact with the support substrate, it is preferable that the difference in refractive index between the conductive resin thin film and the support substrate is smaller. For example, the absolute value of the difference in refractive index is preferably less than 0.4. The refractive index of the conductive resin thin film is preferably 1.8 or less. The refractive index of the conductive resin thin film can be set to the desired value by appropriately selecting the type of resin used for the electrode film body, so the relationship of the refractive index with the support substrate is set within the above range. can do.

  If a dispersion liquid in which wires are dispersed in a photosensitive material and a photocurable monomer used for a photoresist is used, an electrode having a predetermined pattern shape can be easily formed by a coating method and photolithography. For example, trimethylolpropane triacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name “NK Ester-TMPT”) and a polymerization initiator (manufactured by Ciba-Geigy Japan Ltd., trade name “Irgacure 907”) can be used as the dispersion. .

  Examples of the method of applying the dispersion in which the wire is dispersed include dipping method, bar coater coating method, spin coater coating method, doctor blade method, spray coating method, screen mesh printing method, brush coating, spraying, roll coating, etc. Can do. In addition, when using a thermosetting resin or a photocurable resin, a coating film can be hardened by light irradiation or heating after apply | coating a dispersion liquid.

  Alternatively, the conductive resin thin film may be patterned by applying the dispersion liquid in a pattern by using a predetermined printing method such as a relief printing method and solidifying the dispersion. Furthermore, after the dispersion liquid is applied to the entire surface and solidified, a photoresist is further applied thereon, and the conductive resin thin film is patterned by forming a predetermined pattern using a photolithography method. Good.

  The conductive resin thin film preferably has a surface roughness of 10 nm or less, a transmittance of 80% or more, and a sheet resistance of 1000 Ω / □ or less.

  As described above, ITO is frequently used for the electrode exhibiting optical transparency. Since the refractive index of ITO is about 2, the refractive index of the glass substrate is about 1.5, and the refractive index of the portion in contact with ITO (for example, the light emitting layer or the adjacent layer) is about 1.7, it shows light transmittance. When ITO is used as the electrode, the organic EL element has a structure in which ITO having a high refractive index is sandwiched between a glass substrate having a low refractive index and the light emitting layer. Therefore, a part of the light emitted from the light emitting layer is reflected by the ITO by total reflection or the like, and the light may not be efficiently emitted to the outside. However, by using the conductive resin thin film having a low refractive index as described above, reflection of light at the electrode can be suppressed, and light can be efficiently emitted to the outside.

(Production example)
Hereinafter, a specific production example of one electrode using a conductive resin thin film will be described.

(Production Example 1)
Silver nanowires (major axis average length 1μm, minor axis average length) whose surface was protected with amino group-containing polymer dispersant (product name “Solsperse 24000SC”, manufactured by IC Japan Ltd.) 10 nm). 2 g of this silver nanowire toluene dispersion (containing 1.0 g of silver nanowire) and 0.25 g of trimethylolpropane triacrylate (NK ester-TMPT made by Shin-Nakamura Chemical), which is a photocurable monomer, Polymerization initiator Irgacure 907 (Nippon Ciba-Geigy Co., Ltd.) 0.0025 g is added. This mixed solution is applied onto a 0.7 mm thick glass substrate, heated on a hot plate at 110 ° C. for 20 minutes to remove the solvent, and further cured by irradiating with a UV lamp (6000 mW / cm ² ). Thus, one electrode having a film thickness of 150 nm is obtained. The refractive index of the photocurable resin is 1.5, and the refractive index of one of the obtained electrodes is also 1.5.

(Production Example 2)
Silver nanowires (major axis average length 1μm, minor axis average length) whose surface was protected with amino group-containing polymer dispersant (product name “Solsperse 24000SC”, manufactured by IC Japan Ltd.) 10 nm). 2 g of this silver nanowire toluene dispersion (containing 1.0 g of silver nanowire) and 2.5 g of a poly (ethylenedioxythiophene) / polystyrene sulfonic acid solution (Startron P, BaytronP) are mixed. This mixed solution is applied to a glass substrate having a thickness of 0.7 mm, heated on a hot plate at 200 ° C. for 20 minutes, and the solvent is removed to obtain one electrode having a thickness of 150 nm. BaytronP has a refractive index of 1.7, and the transparent conductive film obtained has a refractive index of 1.7.

(Production Example 3)
Silver nanowires (major axis average length 1μm, minor axis average length) whose surface was protected with amino group-containing polymer dispersant (product name “Solsperse 24000SC”, manufactured by IC Japan Ltd.) 10 nm). A mixed solution in which 0.125 g of dimethyl sulfoxide was mixed with 2.5 g of a solution of poly (ethylenedioxythiophene) / polystyrenesulfonic acid (Startron P, BaytronP), and 2 g of toluene dispersion of the silver nanowire (silver nanowire) (Containing 1.0 g). This mixed solution is applied to a 0.7 mm thick glass substrate, heated on a hot plate at 200 ° C. for 20 minutes, and the solvent is removed to obtain a conductive film having a thickness of 150 nm. BaytronP has a refractive index of 1.7, and the transparent conductive film obtained has a refractive index of 1.7.

<Adjustment of atmosphere around substrate>
After the formation of one of the electrodes and until the step of forming the light emitting layer is completed, the oxygen concentration and the water concentration in the atmosphere around the support substrate are each kept below the atmospheric concentration by volume. That is, immediately after the formation of the conductive resin thin film as one electrode and at least until the formation of the light emitting layer is completed, the oxygen concentration and the water concentration in the atmosphere around the support substrate are respectively set to be less than the atmospheric concentration by volume ratio. keep.

Note that the oxygen concentration and moisture concentration in the atmosphere vary depending on the location and time, etc., but less than the atmospheric concentration in this specification means a state in which a predetermined operation for lowering the oxygen concentration and moisture concentration below the atmospheric concentration has been performed. means. The oxygen concentration in the air atmosphere is about 2 × 10 ⁵ ppm by volume, and the water concentration is about 2 × 10 ⁴ ppm by volume.

  The oxygen concentration and water concentration in the atmosphere around the support substrate are preferably 1000 ppm or less, more preferably 600 ppm or less, further preferably 300 ppm or less, and further preferably 10 ppm or less.

  As a method for lowering the oxygen concentration and moisture concentration in the atmosphere around the support substrate as compared to the air, the atmosphere around the support substrate is preferably an inert gas atmosphere or a vacuum atmosphere. For example, a coating device and a heating device may be arranged in a device that can replace the inside of the device with a vacuum or an inert gas to form an adjacent layer and a light emitting layer. For example, both the step of applying ink and the step of solidifying it may be performed in an inert gas atmosphere, or the step of applying ink may be performed in an inert gas atmosphere, and the solidifying step may be performed in a vacuum atmosphere. preferable.

  Examples of the inert gas include helium gas, argon gas, nitrogen gas, and a mixed gas thereof. Among these, nitrogen gas is preferable from the standpoint of device fabrication. Moreover, when performing a solidification process in a vacuum atmosphere, it is preferable to set it as 10 Pa or less.

<Adjacent layer forming step>
In this step, an ink containing a material to be an adjacent layer is applied on the one electrode, and the adjacent layer is formed by solidifying the ink. In the present embodiment, an ink containing a material to be an adjacent layer is applied and formed on the surface of one electrode 3 and further solidified.

  The ink used for forming the adjacent layer includes a material that becomes the adjacent layer and a solvent or dispersion medium that dissolves or disperses the material. The material for the adjacent layer will be described later. The solvent may be any material that dissolves the material for the adjacent layer. For example, a chlorine-based solvent such as chloroform, methylene chloride, and dichloroethane, an ether-based solvent such as tetrahydrofuran, and an aromatic hydrocarbon-based solvent such as toluene and xylene. And ketone solvents such as acetone and methyl ethyl ketone, ester solvents such as ethyl acetate, butyl acetate and ethyl cellosolve acetate, and water. The dispersion medium may be any liquid that uniformly disperses the material that forms the adjacent layer. For example, the liquid exemplified as the solvent can be used as the dispersion medium as appropriate depending on the material of the adjacent layer.

  Examples of coating methods include spin coating, casting, micro gravure coating, gravure coating, bar coating, roll coating, wire bar coating, dip coating, spray coating, screen printing, flexographic printing, Examples thereof include an offset printing method and an ink jet printing method.

  In this embodiment, a method of heating the thin film is preferable as a method for solidifying the thin film formed by coating. It is preferable to heat at 50 ° C. to 250 ° C. in order to improve the light emission characteristics and lifetime characteristics of the device. The heating time is appropriately set depending on the components of the adjacent layer, and is, for example, about 5 minutes to 2 hours. The adjacent layer may be formed by removing the solvent or dispersion medium contained in the ink by leaving the thin film formed by coating for a predetermined time.

<Light emitting layer forming step>
In this step, an ink containing a material to be a light emitting layer is applied and formed on the one electrode, and further solidified to form a light emitting layer. In addition, when ink is applied and formed on one electrode, ink may be applied and formed on the surface of one electrode. However, as in the present embodiment, between one electrode and the light emitting layer. When a predetermined layer is disposed, ink is applied and formed on the surface of the predetermined layer (adjacent layer in the present embodiment) as one electrode.

  In this embodiment, a method of heating the thin film is preferable as a method for solidifying the thin film formed by coating. In order to improve the light emission characteristics and lifetime characteristics of the element, it is preferable to heat at 50 ° C. to 250 ° C. The heating time is appropriately set depending on the components of the light emitting layer, and is, for example, about 5 minutes to 2 hours. The light-emitting layer may be formed by removing the solvent or dispersion medium contained in the ink by leaving the thin film formed by coating for a predetermined time.

  From the formation of the above one electrode to the formation of the light emitting layer, the oxygen concentration and the moisture concentration in the atmosphere around the support substrate are each kept in a volume ratio lower than the atmospheric concentration.

<The other electrode forming step>
In the other electrode formation step, the other electrode 6 is formed on the light emitting layer 5.

  Among the components of the organic EL element, the light emitting layer has a great influence on the light emitting characteristics. Therefore, controlling the atmosphere around the substrate during the production of layers other than the light emitting layer is from the viewpoint of improving the light emitting characteristics of the element. Although it is difficult to imagine, by forming not only the light emitting layer but also the adjacent layer in an atmosphere in which the oxygen concentration and the moisture concentration are lower than the atmosphere, the device lifetime can be improved as shown in the examples.

Also, if one electrode is formed only of an inorganic material such as ITO, one electrode will not absorb moisture, and immediately before the adjacent layer or the light emitting layer is formed on one electrode, for example, O _2. It is possible to recover the deterioration of one electrode by performing a surface treatment such as plasma treatment, but when a conductive resin thin film containing a resin is formed as one electrode as in this embodiment, oxygen As a result, the wire dispersed in the resin is oxidized, and the resin absorbs moisture. As a result, not only the surface of the conductive resin thin film but also the inside deteriorates. However, in this embodiment, after the formation of one electrode and until the step of forming the light emitting layer is completed, the oxygen concentration and the moisture concentration in the atmosphere around the support substrate are each kept below the atmospheric concentration by volume ratio. Therefore, it can suppress that a conductive resin thin film deteriorates itself during element manufacture. This makes it possible to improve element characteristics while using a conductive resin thin film that has a simpler manufacturing process than ITO, and to obtain an organic EL element with improved element characteristics by a simple manufacturing method.

  Although the adjacent layer is provided in this embodiment, the adjacent layer may not be provided in other embodiments, and a predetermined layer may be further disposed between the electrodes in addition to the above-described adjacent layer. In this embodiment, the adjacent layer is formed by the above-described predetermined coating method. However, the formation method of the adjacent layer is not particularly limited, and is appropriately formed by a predetermined method in consideration of required characteristics and process simplicity. May be.

  Hereinafter, the configuration of the organic EL element to which the present invention is applicable and its constituent elements will be described in more detail. Note that a layer that can be formed by a coating method is preferably formed by a method similar to the method for forming the light-emitting layer described above, from the viewpoint of simplicity of the process and uniformity of the film thickness.

  Examples of the layer provided between the anode and the light emitting layer include a hole injection layer, a hole transport layer, and an electron block layer. When both the hole injection layer and the hole transport layer are provided between the anode and the light-emitting layer, the layer in contact with the anode is called a hole injection layer, and the layers other than the hole injection layer are positive. It is called a hole transport layer.

  The hole injection layer is a layer having a function of improving hole injection efficiency from the anode. The hole transport layer is a layer having a function of improving hole injection from the anode, the hole injection layer, or the hole transport layer closer to the anode. The electron blocking layer is a layer having a function of blocking electron transport. In the case where the hole injection layer and / or the hole transport layer has a function of blocking electron transport, these layers may also serve as an electron blocking layer.

  The function of the electron blocking layer as a layer for blocking electron transport can be confirmed, for example, by producing an element for passing only an electronic current and confirming the blocking effect by reducing the current value.

  Examples of the layer provided between the cathode and the light emitting layer include an electron injection layer, an electron transport layer, and a hole blocking layer. When both the electron injection layer and the electron transport layer are provided between the cathode and the light emitting layer, the layer in contact with the cathode is referred to as the electron injection layer, and the layers other than the electron injection layer are referred to as the electron transport layer. There is.

  The electron injection layer is a layer having a function of improving electron injection efficiency from the cathode. The electron transport layer is a layer having a function of improving electron injection from the cathode, the electron injection layer, or the electron transport layer closer to the cathode. The hole blocking layer is a layer having a function of blocking hole transport. In the case where the electron injection layer and / or the electron transport layer have a function of blocking hole transport, these layers may also serve as the hole blocking layer.

  The function of the hole blocking layer as a layer for blocking hole transport can be confirmed, for example, by fabricating an element that allows only a hole current to flow. For example, an element that does not include a hole blocking layer and that allows only a hole current to flow, and an element that includes a hole blocking layer inserted into the element are manufactured. It can be confirmed that the hole blocking layer has a function of blocking hole transport.

An example of a layer structure that can be taken by the organic EL element of the present embodiment is shown below.
a) anode / light emitting layer / cathode b) anode / hole injection layer / light emitting layer / cathode c) anode / hole injection layer / light emitting layer / electron injection layer / cathode d) anode / hole injection layer / light emitting layer / Electron transport layer / cathode e) anode / hole injection layer / light emitting layer / electron transport layer / electron injection layer / cathode f) anode / hole transport layer / light emitting layer / cathode g) anode / hole transport layer / light emitting layer / Electron injection layer / cathode h) anode / hole transport layer / light emitting layer / electron transport layer / cathode i) anode / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode j) anode / hole Injection layer / hole transport layer / light emitting layer / cathode k) anode / hole injection layer / hole transport layer / light emitting layer / electron injection layer / cathode l) anode / hole injection layer / hole transport layer / light emitting layer / Electron transport layer / cathode m) anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode n) anode / light emitting layer / electron injection layer / cathode (where, No. "/" indicates that the layers sandwiching the symbol "/" are laminated adjacent to each other. Hereinafter the same.)
The organic EL element of the present embodiment may have two or more light emitting layers. In any one of the layer configurations of a) to n) above, if the laminate sandwiched between the anode and the cathode is “structural unit A”, the configuration of the organic EL element having two light emitting layers is as follows. Examples of the layer structure shown in o) below can be given. Note that the two (structural unit A) layer structures may be the same or different.
o) Anode / (structural unit A) / charge generating layer / (structural unit A) / cathode If “(structural unit A) / charge generating layer” is “structural unit B”, it has three or more light emitting layers. Examples of the structure of the organic EL element include the layer structure shown in p) below.
p) anode / (structural unit B) x / (structural unit A) / cathode The symbol “x” represents an integer of 2 or more, and (structural unit B) x is a stack in which the structural unit B is stacked in x stages. Represents the body. A plurality of (structural units B) may have the same or different layer structure.

  Here, the charge generation layer is a layer that generates holes and electrons by applying an electric field. Examples of the charge generation layer include a thin film made of vanadium oxide, indium tin oxide (abbreviated as ITO), molybdenum oxide, or the like.

  The organic EL element is usually provided on the support substrate so that the anode is disposed on the support substrate side as in the present embodiment. That is, in the configurations of a) to p), the organic EL element is provided on the support substrate so that the left layer is disposed closer to the support substrate. In another embodiment, the organic EL element may be provided on the support substrate so that the cathode is disposed on the support substrate side.

  When the anode is arranged on the support substrate side as in the present embodiment, the anode corresponds to one electrode and the cathode corresponds to the other electrode. Therefore, in the configurations of a) to p), on the left side of the light emitting layer. Adjacent layers correspond to the adjacent layers described above. When such an adjacent layer can be formed by a coating method, it is preferable to form the adjacent layer by a method similar to the method for forming the adjacent layer described above. However, in the structures a) to p), when the left layer of the light emitting layer is an anode, there is no adjacent layer.

  In the embodiment in which the cathode is disposed on the support substrate side, the cathode corresponds to one electrode and the anode corresponds to the other electrode. Therefore, in the configurations a) to p), the layer adjacent to the right side of the light emitting layer is the above-described layer. Corresponds to the adjacent layer. When such an adjacent layer can be formed by a coating method, it is preferable to form the adjacent layer by a method similar to the method for forming the adjacent layer described above. However, in the configurations of a) to p), when the layer adjacent to the right side of the light emitting layer is a cathode, there is no adjacent layer.

  Organic EL elements are roughly classified into bottom emission type elements configured to emit light from the support substrate side and top emission type elements configured to emit light from the side opposite to the support substrate side. The organic EL element of the embodiment may be any type of element, and in the present embodiment, it is possible to easily form one electrode exhibiting light transmittance, and therefore it is preferable to constitute a bottom emission type element. For example, in a bottom emission type organic EL element, light emitted from the light emitting layer is emitted to the outside through one electrode and a supporting substrate by using one electrode and a substrate exhibiting light transmittance.

  The order of the layers to be laminated, the number of layers, and the thickness of each layer can be appropriately set in consideration of the light emission efficiency and the element lifetime.

  Next, the material and forming method of each layer constituting the organic EL element will be described more specifically.

<Board>
A substrate that is not chemically changed in the process of manufacturing the organic EL element is suitably used. For example, glass, plastic, a polymer film, a silicon plate, and a laminate of these are used.

<A pair of electrodes>
One of the pair of electrodes functions as an anode, and the other electrode functions as a cathode. One of the pair of electrodes is an electrode exhibiting optical transparency, and the refractive index is preferably 1.5 to 1.8.

  As the electrode exhibiting light transmittance, the conductive resin thin film as one of the electrodes described above can be used, and those having high electrical conductivity and light transmittance are preferably used. When this conductive resin thin film is used as an anode, it is preferable that holes can be easily injected into the light emitting layer, and when the conductive resin thin film is used as a cathode, the work function is small, and electron injection into the light emitting layer is possible. Easy materials are preferably used.

  One of the pair of electrodes is a light-transmitting electrode, and another electrode different from the light-transmitting electrode is usually an opaque electrode. The opaque electrode is preferably an electrode that reflects light.

  As the material of the opaque electrode, for example, alkali metal, alkaline earth metal, transition metal and Group 13 metal of the periodic table can be used. For example, lithium, sodium, potassium, rubidium, cesium, beryllium, magnesium, calcium, Metals such as strontium, barium, aluminum, scandium, vanadium, zinc, yttrium, indium, cerium, samarium, europium, terbium, ytterbium, two or more alloys of the metals, one or more of the metals, and An alloy with one or more of gold, silver, platinum, copper, manganese, titanium, cobalt, nickel, tungsten, tin, graphite, or a graphite intercalation compound is used. Examples of alloys include magnesium-silver alloys, magnesium-indium alloys, magnesium-aluminum alloys, indium-silver alloys, lithium-aluminum alloys, lithium-magnesium alloys, lithium-indium alloys, calcium-aluminum alloys, and the like. it can.

  The other electrode can be formed by, for example, a vacuum deposition method, a sputtering method, or a laminating method in which a metal thin film is thermocompression bonded.

  The film thickness of the other electrode is appropriately set in consideration of the electrode characteristics such as conductivity and light transmittance, and is, for example, about 1 nm to 1 μm, preferably 2 nm to 500 nm, more preferably 5 nm to 200 nm. It is.

<Hole injection layer>
When a hole injection layer is provided adjacent to the light emitting layer between the light emitting layer and one electrode, this hole injection layer is provided as an adjacent layer. In this case, it is preferable to form the hole injection layer by a coating method using an ink containing a material to be the following hole injection layer.

  As the hole injection material constituting the hole injection layer, oxides such as vanadium oxide, molybdenum oxide, ruthenium oxide, and aluminum oxide, phenylamine type, starburst type amine type, phthalocyanine type, amorphous carbon, polyaniline, And polythiophene derivatives.

  Examples of the method for forming the hole injection layer include film formation from a solution containing a hole injection material. For example, the liquid illustrated as the solvent or dispersion medium of the ink used when forming an adjacent layer can be used as a solvent used for the film-forming from a solution.

  As a film forming method from a solution, a spin coating method, a casting method, a micro gravure coating method, a gravure coating method, a bar coating method, a roll coating method, a wire bar coating method, a dip coating method, a spray coating method, a screen printing method, Examples of the application method include a flexographic printing method, an offset printing method, and an ink jet printing method.

  The film thickness of the hole injection layer is appropriately determined in consideration of required characteristics and process simplicity, and is, for example, 1 nm to 1 μm, preferably 2 nm to 500 nm, and more preferably 5 nm to 200 nm.

<Hole transport layer>
When a hole transport layer is provided adjacent to the light emitting layer between the light emitting layer and one of the electrodes, this hole transport layer is provided as an adjacent layer. In this case, it is preferable to form the hole transport layer by a coating method using an ink containing a material to be the following hole transport layer.

  As the hole transport material constituting the hole transport layer, polyvinylcarbazole or a derivative thereof, polysilane or a derivative thereof, a polysiloxane derivative having an aromatic amine in a side chain or a main chain, a pyrazoline derivative, an arylamine derivative, a stilbene derivative, Triphenyldiamine derivative, polyaniline or derivative thereof, polythiophene or derivative thereof, polyarylamine or derivative thereof, polypyrrole or derivative thereof, poly (p-phenylene vinylene) or derivative thereof, or poly (2,5-thienylene vinylene) or Examples thereof include derivatives thereof.

  Among these, hole transport materials include polyvinyl carbazole or derivatives thereof, polysilane or derivatives thereof, polysiloxane derivatives having aromatic amine compound groups in the side chain or main chain, polyaniline or derivatives thereof, polythiophene or derivatives thereof, poly Polymeric hole transport materials such as arylamine or derivatives thereof, poly (p-phenylene vinylene) or derivatives thereof, or poly (2,5-thienylene vinylene) or derivatives thereof are preferred, and polyvinylcarbazole or derivatives thereof are more preferred. , Polysilane or a derivative thereof, and a polysiloxane derivative having an aromatic amine in the side chain or main chain. In the case of a low-molecular hole transport material, it is preferably used by being dispersed in a polymer binder.

  The method for forming the hole transport layer is not particularly limited, but in the case of a low molecular hole transport material, film formation from a mixed solution containing a polymer binder and a hole transport material can be exemplified. Examples of molecular hole transport materials include film formation from a solution containing a hole transport material.

  Examples of the film forming method from a solution include the same coating method as the above-described film forming method of the hole injection layer.

  As the polymer binder to be mixed, those that do not extremely inhibit charge transport are preferable, and those that weakly absorb visible light are preferably used. For example, polycarbonate, polyacrylate, polymethyl acrylate, polymethyl methacrylate, polystyrene, poly Examples thereof include vinyl chloride and polysiloxane.

  The film thickness of the hole transport layer is appropriately set in consideration of required characteristics and process simplicity, and is, for example, 1 nm to 1 μm, preferably 2 nm to 500 nm, and more preferably 5 nm to 200 nm.

<Light emitting layer>
The light emitting layer is usually formed of an organic substance that mainly emits fluorescence and / or phosphorescence, or an organic substance and a dopant that assists the organic substance. The dopant is added, for example, in order to improve the luminous efficiency and change the emission wavelength. The organic substance may be a low molecular compound or a high molecular compound, and the light emitting layer preferably contains a high molecular compound having a polystyrene-equivalent number average molecular weight of 10 ³ to 10 ⁸ from the viewpoint of solubility in a solvent. . Examples of the light emitting material constituting the light emitting layer include the following dye materials, metal complex materials, polymer materials, and dopant materials.

(Dye material)
Examples of dye-based materials include cyclopentamine derivatives, tetraphenylbutadiene derivative compounds, triphenylamine derivatives, oxadiazole derivatives, pyrazoloquinoline derivatives, distyrylbenzene derivatives, distyrylarylene derivatives, pyrrole derivatives, thiophene ring compounds. Pyridine ring compounds, perinone derivatives, perylene derivatives, oligothiophene derivatives, oxadiazole dimers, pyrazoline dimers, quinacridone derivatives, coumarin derivatives, and the like.

(Metal complex materials)
Examples of the metal complex material include rare earth metals such as Tb, Eu, and Dy, or Al, Zn, Be, Ir, Pt, etc. as a central metal, and oxadiazole, thiadiazole, phenylpyridine, phenylbenzimidazole, quinoline. Examples include metal complexes having a structure or the like as a ligand, such as iridium complexes, platinum complexes, etc., metal complexes having light emission from a triplet excited state, aluminum quinolinol complexes, benzoquinolinol beryllium complexes, benzoxazolyl zinc A complex, a benzothiazole zinc complex, an azomethylzinc complex, a porphyrin zinc complex, a phenanthroline europium complex, and the like can be given.

(Polymer material)
As polymer materials, polyparaphenylene vinylene derivatives, polythiophene derivatives, polyparaphenylene derivatives, polysilane derivatives, polyacetylene derivatives, polyfluorene derivatives, polyvinyl carbazole derivatives, the above dye materials and metal complex light emitting materials are polymerized. Things can be mentioned.

  Among the light emitting materials, examples of the material that emits blue light include distyrylarylene derivatives, oxadiazole derivatives, and polymers thereof, polyvinylcarbazole derivatives, polyparaphenylene derivatives, and polyfluorene derivatives. Of these, polymer materials such as polyvinyl carbazole derivatives, polyparaphenylene derivatives, and polyfluorene derivatives are preferred.

  Examples of materials that emit green light include quinacridone derivatives, coumarin derivatives, and polymers thereof, polyparaphenylene vinylene derivatives, polyfluorene derivatives, and the like. Of these, polymer materials such as polyparaphenylene vinylene derivatives and polyfluorene derivatives are preferred.

Examples of materials that emit red light include coumarin derivatives, thiophene ring compounds, and polymers thereof, polyparaphenylene vinylene derivatives, polythiophene derivatives, and polyfluorene derivatives. Among these, polymer materials such as polyparaphenylene vinylene derivatives, polythiophene derivatives, and polyfluorene derivatives are preferable.
(Dopant material)
Examples of the dopant material include perylene derivatives, coumarin derivatives, rubrene derivatives, quinacridone derivatives, squalium derivatives, porphyrin derivatives, styryl dyes, tetracene derivatives, pyrazolone derivatives, decacyclene, phenoxazone, and the like. In addition, the thickness of such a light emitting layer is usually about 2 nm-200 nm.

  The light emitting layer can be formed by the above-described method by a coating method using an ink containing the material to be the light emitting layer described above. The ink containing the material that becomes the light emitting layer includes the material that becomes the light emitting layer and a solvent or dispersion medium that dissolves or disperses the material. As the solvent, any solvent that dissolves the material to be the light-emitting layer may be used. For example, a chlorine-based solvent such as chloroform, methylene chloride, and dichloroethane, an ether-based solvent such as tetrahydrofuran, an aromatic hydrocarbon-based solvent such as toluene and xylene, Examples thereof include ketone solvents such as acetone and methyl ethyl ketone, and ester solvents such as ethyl acetate, butyl acetate, and ethyl cellosolve acetate. The dispersion medium may be a liquid that uniformly disperses the material that becomes the light emitting layer, and the liquid exemplified as the solvent can be appropriately used as the dispersion medium depending on the material.

<Electron transport layer>
When an electron transport layer is provided adjacent to the light emitting layer between the light emitting layer and one of the electrodes, this electron transport layer is provided as an adjacent layer. In this case, it is preferable to form an electron transport layer by the coating method mentioned above using the ink containing the material used as the following electron transport layers.

  As the electron transport material constituting the electron transport layer, known materials can be used, such as oxadiazole derivatives, anthraquinodimethane or derivatives thereof, benzoquinone or derivatives thereof, naphthoquinone or derivatives thereof, anthraquinones or derivatives thereof, tetracyanoanthra Quinodimethane or derivatives thereof, fluorenone derivatives, diphenyldicyanoethylene or derivatives thereof, diphenoquinone derivatives, or metal complexes of 8-hydroxyquinoline or derivatives thereof, polyquinoline or derivatives thereof, polyquinoxaline or derivatives thereof, polyfluorene or derivatives thereof, etc. Can be mentioned.

  Among these, as an electron transport material, an oxadiazole derivative, benzoquinone or a derivative thereof, anthraquinone or a derivative thereof, a metal complex of 8-hydroxyquinoline or a derivative thereof, a polyquinoline or a derivative thereof, a polyquinoxaline or a derivative thereof, a polyfluorene Or a derivative thereof is preferable, and 2- (4-biphenylyl) -5- (4-t-butylphenyl) -1,3,4-oxadiazole, benzoquinone, anthraquinone, tris (8-quinolinol) aluminum, and polyquinoline are further included. preferable.

  There are no particular restrictions on the method for forming the electron transport layer, but for low molecular weight electron transport materials, vacuum deposition from powder or film formation from a solution or a molten state can be used. Examples of the material include film formation from a solution or a molten state. In the case of forming a film from a solution or a molten state, a polymer binder may be used in combination. Examples of the method for forming an electron transport layer from a solution include the same film formation method as the method for forming a hole injection layer from a solution described above.

  The film thickness of the electron transport layer is appropriately set in consideration of required characteristics and process simplicity, and is, for example, 1 nm to 1 μm, preferably 2 nm to 500 nm, and more preferably 5 nm to 200 nm.

<Electron injection layer>
When an electron injection layer is provided adjacent to the light emitting layer between the light emitting layer and one of the electrodes, this electron injection layer is provided as an adjacent layer. In this case, it is preferable to form the electron injection layer by the above-described coating method using an ink containing a material to be the following electron injection layer.

  As the material constituting the electron injecting layer, an optimal material is appropriately selected according to the type of the light emitting layer, and an alloy containing at least one of alkali metal, alkaline earth metal, alkali metal and alkaline earth metal, alkali A metal or alkaline earth metal oxide, halide, carbonate, or a mixture of these substances can be given. Examples of alkali metals, alkali metal oxides, halides, and carbonates include lithium, sodium, potassium, rubidium, cesium, lithium oxide, lithium fluoride, sodium oxide, sodium fluoride, potassium oxide, potassium fluoride , Rubidium oxide, rubidium fluoride, cesium oxide, cesium fluoride, lithium carbonate, and the like. Examples of alkaline earth metals, alkaline earth metal oxides, halides and carbonates include magnesium, calcium, barium, strontium, magnesium oxide, magnesium fluoride, calcium oxide, calcium fluoride, barium oxide, Examples thereof include barium fluoride, strontium oxide, strontium fluoride, and magnesium carbonate. The electron injection layer may be composed of a laminate in which two or more layers are laminated, and examples thereof include LiF / Ca. The electron injection layer is formed by vapor deposition, sputtering, printing, or the like. The thickness of the electron injection layer is preferably about 1 nm to 1 μm.

  The organic EL elements described above can be suitably used for curved or planar illumination devices, for example, planar light sources used as light sources for scanners, and light emitting devices such as display devices.

  Examples of the display device including an organic EL element include a segment display device and a dot matrix display device. The dot matrix display device includes an active matrix display device and a passive matrix display device. An organic EL element is used as a light emitting element constituting each pixel in an active matrix display device and a passive matrix display device. The organic EL element is used as a light emitting element or a backlight constituting each segment in the segment display device, and is used as a backlight in the liquid crystal display device.

  Hereinafter, in order to confirm that the device characteristics are improved by producing the organic EL device in a predetermined atmosphere, the organic EL device was produced in an atmosphere in which the gas concentration was controlled. As one of the electrodes, an ITO thin film was used in place of the conductive resin thin film. However, the following experimental examples and comparison show that device characteristics are improved by producing at least the adjacent layer and the light emitting layer in a predetermined atmosphere. Confirmed in the examples.

(Experimental example 1)
An organic EL element having the following configuration was produced.
“Glass substrate / ITO (150 nm) / Baytron P (65 nm) / Polymer compound 1 (20 nm) / Polymer compound 2 (65 nm) / Ba (5 nm) / Al (80 nm)”
First, a glass substrate on which an ITO film (anode) having a thickness of 150 nm was formed on the surface by sputtering was prepared. On this glass substrate, a suspension of poly (3,4) ethylenedioxythiophene / polystyrene sulfonic acid (Starc; Baytron P) was applied by spin coating to form a coating film having a thickness of 65 nm. A hole injection layer was obtained by drying at 200 ° C. for 10 minutes on a hot plate. The hole injection layer was formed in an air atmosphere. The oxygen concentration in the air atmosphere is about 2 × 10 ⁵ ppm by volume, and the water concentration is about 2 × 10 ⁴ ppm by volume.

  Next, the polymer compound 1 was dissolved in tetralin to prepare a tetralin solution 1. The concentration of the polymer compound 1 in the tetralin solution 1 was 1.0% by weight. Next, in a nitrogen atmosphere in which the oxygen concentration and the water concentration are each controlled to 10 ppm or less by volume, the tetralin solution 1 is applied onto the substrate by spin coating, and the coating film for a hole transport layer having a thickness of 20 nm is formed. Was deposited. This was left for 10 minutes in an atmosphere in which the oxygen concentration was controlled to 400 ppm to 450 ppm by volume and the water concentration was controlled to 440 ppm to 540 ppm by volume (Experimental Examples 1 and 2 and Comparative Examples 1 and 2 below). 3, the hole transport layer corresponds to the adjacent layer). Next, a hole transport layer was obtained by heating at 180 ° C. for 1 hour in an atmosphere in which the oxygen concentration was controlled to 400 ppm to 450 ppm by volume and the water concentration was controlled to 440 ppm to 540 ppm by volume.

  Next, the high molecular compound 2 was melt | dissolved in tetralin, and the tetralin solution 2 was prepared. The concentration of the polymer compound 2 in the tetralin solution 2 was 1.37% by weight. In a nitrogen atmosphere in which the oxygen concentration and the water concentration were each controlled to 10 ppm or less by volume, the tetralin solution 2 was applied onto the substrate by spin coating to form a light emitting layer coating film having a thickness of 65 nm. This was left for 10 minutes in an atmosphere in which the oxygen concentration was controlled to 400 ppm to 450 ppm by volume and the water concentration was controlled to 500 ppm to 540 ppm by volume. Next, a light emitting layer was obtained by heating at 130 ° C. for 10 minutes in an atmosphere in which the oxygen concentration was controlled to 400 ppm to 450 ppm by volume and the water concentration was controlled to 500 ppm to 540 ppm by volume. In the step of forming the hole transport layer and the light emitting layer, the pressure of the substrate atmosphere was set to atmospheric pressure.

Next, after reducing the pressure to 1.0 × 10 ⁻⁴ Pa or less, barium was vapor-deposited at about 5 nm and aluminum was then vapor-deposited at about 80 nm as a cathode. After vapor deposition, sealing was performed using a glass substrate to produce an organic EL element.

When the produced organic EL device was driven at a constant current at an initial luminance of 5,000 cd / m ² , the time (life) until the luminance became 50% of the initial luminance was 131 hours. When this lifetime was converted into a lifetime when driven at a constant current with an initial luminance of 3,000 cd / m ² , it was 365 hours (conversion formula = 131 × (5000/3000) ² ).

(Experimental example 2)
An organic EL element having the following configuration was produced.
“Glass substrate / ITO (150 nm) / Baytron P (65 nm) / Polymer compound 1 (20 nm) / Polymer compound 2 (65 nm) / Ba (5 nm) / Al (80 nm)”
First, a glass substrate on which an ITO film (anode) having a thickness of 150 nm was formed on the surface by sputtering was prepared. On this glass substrate, a suspension of poly (3,4) ethylenedioxythiophene / polystyrene sulfonic acid (Starc; Baytron P) was applied by spin coating to form a coating film having a thickness of 65 nm. A hole injection layer was obtained by drying at 200 ° C. for 10 minutes on a hot plate. The hole injection layer was formed in an air atmosphere.

  Next, a tetralin solution 1 was prepared in the same manner as in Experimental Example 1. In a nitrogen atmosphere in which the oxygen concentration and water concentration are each controlled to 10 ppm or less by volume, the tetralin solution 1 is applied onto the substrate by spin coating to form a coating film for a hole transport layer having a thickness of 20 nm. Filmed. Furthermore, the hole transport layer was obtained by heating at 180 ° C. for 1 hour in a nitrogen atmosphere in which the oxygen concentration and the water concentration were each controlled to 10 ppm or less by volume.

  Next, a tetralin solution 2 was prepared in the same manner as in Experimental Example 1. In a nitrogen atmosphere in which the oxygen concentration and the water concentration were each controlled to 10 ppm or less by volume, the tetralin solution 2 was applied onto the substrate by spin coating to form a light emitting layer coating film having a thickness of 65 nm. Further, a light emitting layer was obtained by heating at 130 ° C. for 10 minutes in a nitrogen atmosphere in which the oxygen concentration and the water concentration were each controlled to 10 ppm or less by volume. In the step of forming the hole transport layer and the light emitting layer, the pressure of the substrate atmosphere was set to atmospheric pressure.

Next, after reducing the pressure to 1.0 × 10 ⁻⁴ Pa or less, barium was vapor-deposited at about 5 nm and aluminum was then vapor-deposited at about 80 nm as a cathode. After vapor deposition, sealing was performed using a glass substrate to produce an organic EL element.

When the produced organic EL element was driven at a constant current at an initial luminance of 3,000 cd / m ² , the time (life) until the luminance became 50% of the initial luminance was 415 hours.

(Comparative Example 1)
An organic EL element having the following configuration was produced.
“Glass substrate / ITO (150 nm) / Baytron P (65 nm) / Polymer compound 1 (20 nm) / Polymer compound 2 (65 nm) / Ba (5 nm) / Al (80 nm)”
First, a glass substrate on which an ITO film (anode) having a thickness of 150 nm was formed on the surface by sputtering was prepared. On this substrate, a suspension of poly (3,4) ethylenedioxythiophene / polystyrenesulfonic acid (Starc; Baytron P) was applied by spin coating to form a coating film having a thickness of 65 nm. The hole injection layer was obtained by drying on a plate at 200 ° C. for 10 minutes. The hole injection layer was formed in an air atmosphere.

  Next, a tetralin solution 1 was prepared in the same manner as in Experimental Example 1. In a nitrogen atmosphere in which the oxygen concentration and water concentration are each controlled to 10 ppm or less by volume, the tetralin solution 1 is applied onto the substrate by spin coating to form a coating film for a hole transport layer having a thickness of 20 nm. Filmed. Furthermore, the hole transport layer was obtained by heating at 180 ° C. for 1 hour in a nitrogen atmosphere in which the oxygen concentration and the water concentration were each controlled to 10 ppm or less by volume.

  Next, a tetralin solution 2 was prepared in the same manner as in Experimental Example 1. In the air atmosphere, the tetralin solution 2 was applied onto the substrate by a spin coating method to form a light emitting layer coating film having a film thickness of 65 nm. This was left in the air for 10 minutes. Next, a light emitting layer was obtained by heating at 130 ° C. for 10 minutes in a nitrogen atmosphere in which the oxygen concentration and water concentration were each controlled to 10 ppm or less by volume. In the step of forming the hole transport layer and the light emitting layer, the pressure of the substrate atmosphere was set to atmospheric pressure.

Next, after reducing the pressure to 1.0 × 10 ⁻⁴ Pa or less, barium was vapor-deposited at about 5 nm and aluminum was then vapor-deposited at about 80 nm as a cathode. After vapor deposition, sealing was performed using a glass substrate to produce an organic EL element.

When the produced organic EL device was driven at a constant current at an initial luminance of 3,000 cd / m ² , the time (life) until the luminance became 50% of the initial luminance was 266 hours.

(Comparative Example 2)
An organic EL element having the following configuration was produced.
“Glass substrate / ITO (150 nm) / Baytron P (65 nm) / Polymer compound 1 (20 nm) / Polymer compound 2 (65 nm) / Ba (5 nm) / Al (80 nm)”
First, a glass substrate on which an ITO film (anode) having a thickness of 150 nm was formed on the surface by sputtering was prepared. On this glass substrate, a suspension of poly (3,4) ethylenedioxythiophene / polystyrene sulfonic acid (Starc; Baytron P) was applied by spin coating to form a coating film having a thickness of 65 nm. A hole injection layer was obtained by drying at 200 ° C. for 10 minutes on a hot plate. The hole injection layer was formed in an air atmosphere.

  Next, a tetralin solution 1 was prepared in the same manner as in Experimental Example 1. In the air atmosphere, the tetralin solution 1 was applied onto the substrate by a spin coating method to form a coating film for a hole transport layer having a thickness of 20 nm. This was left in the air for 10 minutes. Next, a hole transport layer was obtained by heating at 180 ° C. for 1 hour in a nitrogen atmosphere in which the oxygen concentration and the water concentration were each controlled to 10 ppm or less by volume.

  Next, a tetralin solution 2 was prepared in the same manner as in Experimental Example 1. In the air atmosphere, the tetralin solution 2 was applied onto the substrate by a spin coating method to form a light emitting layer coating film having a film thickness of 65 nm. This was left in the air for 10 minutes. Next, a light emitting layer was obtained by heating at 130 ° C. for 10 minutes in a nitrogen atmosphere in which the oxygen concentration and water concentration were each controlled to 10 ppm or less by volume. In the step of forming the hole transport layer and the light emitting layer, the pressure of the substrate atmosphere was set to atmospheric pressure.

Next, after reducing the pressure to 1.0 × 10 ⁻⁴ Pa or less, barium was vapor-deposited at about 5 nm and aluminum was then vapor-deposited at about 80 nm as a cathode. After vapor deposition, sealing was performed using a glass substrate to produce an organic EL element.

When the produced organic EL device is driven at a constant current at an initial luminance of 3,000 cd / m ² , the time (life) until the luminance becomes 50% of the initial luminance is 236 hours, and the initial luminance is 5,000 cd / m. When driving at a constant current at ² , the time (life) until the luminance became 50% of the initial luminance was 80 hours.

(Comparative Example 3)
An organic EL element having the following configuration was produced.
“Glass substrate / ITO (150 nm) / Baytron P (65 nm) / Polymer compound 1 (20 nm) / Polymer compound 2 (65 nm) / Ba (5 nm) / Al (80 nm)”
First, a glass substrate on which an ITO film (anode) having a thickness of 150 nm was formed on the surface by sputtering was prepared. On this glass substrate, a suspension of poly (3,4) ethylenedioxythiophene / polystyrene sulfonic acid (Starc; Baytron P) was applied by spin coating to form a coating film having a thickness of 65 nm. A hole injection layer was obtained by drying at 200 ° C. for 10 minutes on a hot plate. The hole injection layer was formed in an air atmosphere.

  Next, a tetralin solution 1 was prepared in the same manner as in Experimental Example 1. In the air atmosphere, the tetralin solution 1 was applied onto the substrate by a spin coating method to form a coating film for a hole transport layer having a film thickness of 20 nm, and left in the air atmosphere for 10 minutes. Next, a hole transport layer was obtained by heating at 180 ° C. for 1 hour in a nitrogen atmosphere in which the oxygen concentration and the water concentration were each controlled to 10 ppm or less by volume.

  Next, a tetralin solution 2 was prepared in the same manner as in Experimental Example 1. In a nitrogen atmosphere in which the oxygen concentration and the water concentration were each controlled to 10 ppm or less by volume, the tetralin solution 2 was applied onto the substrate by spin coating to form a light emitting layer coating film having a thickness of 65 nm. Further, a light emitting layer was obtained by heating at 130 ° C. for 10 minutes in a nitrogen atmosphere in which the oxygen concentration and the water concentration were each controlled to 10 ppm or less by volume. In the step of forming the hole transport layer and the light emitting layer, the pressure of the substrate atmosphere was set to atmospheric pressure.

Next, after reducing the pressure to 1.0 × 10 ⁻⁴ Pa or less, barium was vapor-deposited at about 5 nm and aluminum was then vapor-deposited at about 80 nm as a cathode. After vapor deposition, sealing was performed using a glass substrate to produce an organic EL element.

When the produced organic EL device was driven at a constant current at an initial luminance of 3,000 cd / m ² , the time (life) until the luminance became 50% of the initial luminance was 256 hours.

  Table 2 shows the relationship between the manufacturing conditions of the organic EL elements of Experimental Examples 1 and 2 and Comparative Examples 1, 2, and 3 and the element lifetime.

  From the above results, it was confirmed that the device lifetime was improved by keeping the oxygen concentration and moisture concentration in the atmosphere when forming the hole transport layer and the light emitting layer as the adjacent layers low.

  As an alternative to the above-described polymer compound 1, for example, the following polymer compound 3 is used, and instead of the polymer compound 2, Lumination BP361 (manufactured by Summation) is used to produce an organic EL device in the same manner as in Experimental Examples 1 and 2. Even if it does, the organic EL element with a long element lifetime is realizable like the organic EL element of Experimental example 1,2.

(Polymer Compound 3)
Polymer compound 3 containing two repeating units represented by the following structural formula was synthesized as follows.

Under an inert atmosphere, 2,7-bis (1,3,2-dioxaborolan-2-yl) -9,9-dioctylfluorene (5.20 g), bis (4-bromophenyl)-(4-secondary butylphenyl) ) -Amine (0.14 g), palladium acetate (2.2 mg), tri (2-methylphenyl) phosphine (15.1 mg), Aliquat 336 (0.91 g, manufactured by Aldrich), toluene (70 ml), and 105 Heated to ° C. To this reaction solution, a 2M Na ₂ CO ₃ aqueous solution (19 ml) was added dropwise and refluxed for 4 hours. After the reaction, phenylboric acid (121 mg) was added, and the mixture was further refluxed for 3 hours. Next, an aqueous sodium diethyldithiacarbamate solution was added, and the mixture was stirred at 80 ° C. for 4 hours. After cooling, it was washed 3 times with water (60 ml), 3 times with 3% aqueous acetic acid (60 ml) and 3 times with water (60 ml), and purified by passing through an alumina column and silica gel column. The obtained toluene solution was dropped into methanol (3 L) and stirred for 3 hours, and then the obtained solid was collected by filtration and dried. The yield of the obtained polymer compound 3 was 5.25 g.

The polymer compound 3 had a polystyrene equivalent number average molecular weight of 1.2 × 10 ⁵ and a polystyrene equivalent weight average molecular weight of 2.6 × 10 ⁴ .

  Hereinafter, in order to confirm the effect when the stacking order of the light emitting layers is defined in a predetermined order, an organic EL element having a plurality of light emitting layers and an organic EL element having one light emitting layer were produced.

DESCRIPTION OF SYMBOLS 1 Organic EL element 2 Support substrate 3 One electrode 4 Adjacent layer 5 Light emitting layer 6 The other electrode

Claims (5)

An organic EL device manufacturing method for producing an organic EL device comprising a pair of electrodes and a light emitting layer provided between the electrodes on a support substrate,
Forming a thin film containing a conductive wire and a resin on the support substrate to form one of the pair of electrodes closer to the support substrate; and
Coating the ink containing the material to be the light emitting layer on the one electrode, forming a light emitting layer by further solidifying it, and
Forming the other electrode of the pair of electrodes in this order,
After the formation of the one electrode, until the step of forming the light emitting layer is completed, the oxygen concentration and the water concentration in the atmosphere around the support substrate are each kept below the atmospheric concentration by volume ratio. Manufacturing method of organic EL element. A step of forming an adjacent layer provided between and in contact with the light emitting layer between the one electrode and the light emitting layer, further including a step of forming the light emitting layer after the step of forming the one electrode;
2. The step of forming the adjacent layer is characterized in that the adjacent layer is formed by coating and forming an ink containing a material to be the adjacent layer on the one electrode and further solidifying it. The manufacturing method of organic EL element.   The oxygen concentration and the water concentration in the atmosphere around the support substrate are each maintained at 1000 ppm or less by volume until the step of forming the light emitting layer after the formation of the one electrode is completed. Item 3. A method for producing an organic EL device according to Item 1 or 2.   In the process of forming the said light emitting layer, the said light emitting layer is solidified by heating at 50 to 250 degreeC, The manufacture of the organic electroluminescent element as described in any one of Claims 1-3 characterized by the above-mentioned. Method.   In the step of forming the one electrode, the one electrode having a refractive index of 1.8 or less, an absolute value of a difference in refractive index from the support substrate of less than 0.4, and exhibiting light transmittance The method of manufacturing an organic EL element according to claim 1, wherein the organic EL element is formed.

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