JP2018073591A - Manufacturing method of organic el element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of an organic EL element, which is capable of realizing in which an inverted lamination type in which a cathode is disposed closer to a substrate side than an anode and the polar drive voltage is low.SOLUTION: A manufacturing method of an organic EL element 10 according to an embodiment includes forming, on a substrate 12, an electrode layer 20 containing a metal material which becomes an n-type semiconductor by being modified, forming an organic EL part 16 including a light emitting layer 162 over the electrode layer, and forming the anode 18 on the organic EL part, and the cathode 14 including an n-type semiconductor region is formed by modifying the electrode layer after the step of forming of the electrode layer.SELECTED DRAWING: Figure 1

Description

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

  An organic EL (Electro Luminescence) element includes an anode, an organic EL unit including a light emitting layer, and a cathode. In addition to the light emitting layer, the organic EL part is further provided with a predetermined layer as necessary. The organic EL part may have an electron injection layer disposed between the cathode and the light emitting layer, for example.

  An organic EL element is formed by laminating each layer on a substrate. As the stacking order, there are a form of stacking in order from the anode side and a form of stacking in order from the cathode side. In this specification, the form of lamination from the anode side is referred to as “forward lamination”, and the form of lamination from the cathode side is referred to as “reverse lamination”. For example, Patent Document 1 describes a method for manufacturing an inversely stacked organic EL element.

JP 2005-259550 A

  If the layer configuration is the same in the forward stacking and the reverse stacking, the stacking order is merely reversed as the configuration. Therefore, it is expected that the light emission characteristics of both are equivalent. However, in practice, there is a difference in the characteristics between forward lamination and reverse lamination.

  For example, in the organic EL element in which the electron injection layer is formed by a coating method, the drive voltage may be higher in the reversely stacked organic EL element than in the forward stacked. This is presumably because when an organic EL element is produced by reverse lamination, a step of forming an electron injection layer on the cathode by a coating method occurs, and the cathode is modified at that time.

  Accordingly, an object of the present invention is to provide a method for manufacturing an organic EL element which is a reverse lamination type in which a cathode is disposed on the substrate side with respect to an anode and can realize a low driving voltage.

  The organic EL device manufacturing method according to the present invention includes a step of forming an electrode layer including a metal material that becomes an n-type semiconductor by being modified on a substrate, and an organic layer including a light emitting layer on the electrode layer. A step of forming an EL portion and a step of forming an anode on the organic EL portion, and after the step of forming the electrode layer, the electrode layer is modified to include an n-type semiconductor region A cathode is formed.

  In the manufacturing method of the organic EL element, it is possible to manufacture a reverse lamination type organic EL element in which a cathode, an organic EL part, and an anode are provided in this order from the substrate side. After the step of forming the electrode layer, the electrode layer is modified to form a cathode including an n-type semiconductor region. As described above, since the cathode includes the n-type semiconductor region, electron injection from the cathode toward the organic EL portion is not easily inhibited. As a result, a low drive voltage can be realized.

  The step of forming the organic EL portion includes a step of forming an electron injection layer on the electrode layer and a step of forming the light emitting layer on the electron injection layer. In the forming step, the electron injection layer may be formed by a coating method using a coating liquid containing a solvent or a dispersion medium capable of modifying at least the surface portion of the electrode layer.

  In this manufacturing method, an organic EL element in which the electron injection layer is in contact with the cathode can be manufactured. The electron injection layer is formed by a coating method, and in the coating method, a solvent or a dispersion medium capable of modifying at least the surface portion of the electrode layer is used. With this solvent or dispersion medium, at least the surface portion of the electrode layer can be modified. In this case, the electron injection layer can be formed by a coating method, and at least the surface portion of the electrode layer can be modified during the formation of the electron injection layer to obtain a cathode, thereby improving the productivity of the organic EL element. Can be planned.

  The metallic material can be zinc, titanium or indium.

  The anode may have a property of transmitting visible light. In this case, light can be output from the anode side.

  In the form in which the anode has translucency for visible light, in the step of forming the electrode layer, the first layer and the second layer are formed in order from the substrate side, and the material of the second layer is the metal material. In addition, the material of the first layer may be a metal material having a higher reflectance to visible light than the metal material constituting the second layer.

  In this case, a cathode is formed on the layer corresponding to the first layer, in which a layer corresponding to the second layer and having at least a surface portion modified into an n-type semiconductor region is stacked. Since the material of the first layer is composed of a metal material having a higher reflectance to visible light than the material of the second layer, the light from the light emitting layer in the organic EL element is efficiently reflected at the cathode. Cheap. As a result, the light emission efficiency of the organic EL element is improved.

  The material of the first layer may be a metal material having a reflectance with respect to visible light of 70% or more. An example of the material of the first layer may be aluminum or silver.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the organic electroluminescent element which is a reverse lamination type by which the cathode is arrange | positioned from the anode to the board | substrate side, and can implement | achieve a low drive voltage can be provided.

FIG. 1 is a schematic diagram illustrating a configuration of an example of an organic EL element manufactured by a method for manufacturing an organic EL element according to an embodiment. FIG. 2 is a flowchart of an example of a method for manufacturing the organic EL element shown in FIG. FIG. 3 is a drawing for explaining a process of forming an electrode layer. FIG. 4 is a drawing for explaining a step of forming an electron injection layer. FIG. 5 is a schematic diagram showing a configuration of a modified example of the organic EL element shown in FIG. FIG. 6 is a flowchart of an example of a method for manufacturing the organic EL element shown in FIG. FIG. 7 is a drawing for explaining a step of forming an electrode layer. FIG. 8 is a graph showing experimental results of the experimental element E1a used in the verification experiment 1. FIG. 9 is a graph showing experimental results of the experimental element E1b used in the verification experiment 1. FIG. 10 is a graph showing the measurement result of the luminance with respect to the voltage, which is the experimental result of the verification experiment 2. FIG. 11 is a graph showing the experimental result of the verification experiment 2 and the measurement result of the current density with respect to the voltage. FIG. 12 is a graph showing experimental results of the verification experiment 3. FIG. 13 is a graph showing an experimental result of the verification experiment 4.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The same reference numerals are assigned to the same elements, and duplicate descriptions are omitted. The dimensional ratios in the drawings do not necessarily match those described.

  As schematically shown in FIG. 1, the organic EL element 10 manufactured by the organic EL element manufacturing method of this embodiment includes a cathode 14, an organic EL portion 16 and an anode 18 in this order on a substrate 12. It is configured by stacking. Unless otherwise specified, the organic EL element 10 emits light not from the substrate 12 side but from the anode 18 side.

[substrate]
The substrate 12 that is not chemically changed in the process of manufacturing the organic EL element 10 is preferably used. In the organic EL element 10 of this embodiment, both the substrate 12 having translucency and the substrate 12 having no translucency can be used. For the substrate 12, for example, a glass plate, a polymer film, a silicon plate, a metal foil such as aluminum or copper foil, and a laminate of these are used. A flexible substrate or a rigid substrate is used for the substrate 12 according to the use of the organic EL element 10. The thickness of the substrate 12 is, for example, 30 μm or more and 700 μm or less.

[cathode]
The cathode 14 includes an n-type semiconductor region 14a. For example, as illustrated in FIG. 1, the cathode 14 includes an n-type semiconductor region 14 a at least on a surface portion (a portion on the organic EL portion 16 side). In FIG. 1, the cathode 14 exemplifies a form including the n-type semiconductor region 14a and the metal region 14b, but the entire cathode 14 may be the n-type semiconductor region 14a. The n-type semiconductor region 14a in this specification preferably has an electrical resistivity (Ω · cm) of 9 × 10 ⁻⁵ Ω · cm to 1 × 10 ⁻¹ Ω · cm.

  The cathode 14 includes a metal material that can be modified to form the n-type semiconductor region 14a. Examples of the material (cathode material) of the cathode 14 include indium (In), zinc (Zn), tin (Sn), titanium (Ti), cadmium (Cd), gallium (Ga), and copper (Cu). . Among these, Zn, Ti or In is preferable, and Zn is more preferable. Here, reforming refers to chemical change to a composition different from the original material due to external factors.

  The thickness of the cathode 14 is, for example, 0. 1 nm or more and 500 nm or less. This is because if the thickness is too thin, the effect of providing the cathode 14 is reduced, and if it is too thick, the amount of light absorption increases.

[Organic EL part]
The organic EL unit 16 is provided between the cathode 14 and the anode 18, and performs charge transfer, charge recombination, and the like in accordance with power (for example, voltage) applied between the anode 18 and the cathode 14. It is an organic EL functional part that contributes to the light emission of the organic EL element 10. The organic EL unit 16 includes an electron injection layer 161 and a light emitting layer 162 as functional layers. As will be described later, the organic EL unit 16 may include other functional layers.

(Electron injection layer)
The electron injection layer 161 is disposed in contact with the cathode 14. The electron injection layer 161 includes an ionic polymer.

  Examples of the ionic polymer contained in the electron injection layer 161 include, for example, JP2009-239279A, JP2012-033845A, JP2012-216281A, JP2012-216822A, and Japanese Patent Application Laid-Open No.2012-216822. Examples include the compounds described in 2012-216815.

(Light emitting layer)
The light emitting layer 162 is a functional layer having a function of emitting light (including visible light). Usually, the organic substance mainly emits at least one of fluorescence and phosphorescence, or the 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. It is preferable that the light emitting layer 162 contains the high molecular compound whose number average molecular weight of polystyrene conversion is 10 < ³ > -10 < ⁸ >. The thickness of the light emitting layer 162 is, for example, about 2 nm to 200 nm.

  Examples of the organic substance that is a light-emitting material that mainly emits at least one of fluorescence and phosphorescence include the following dye materials, metal complex materials, and polymer 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, and the like as a central metal, and oxadiazole, thiadiazole, phenylpyridine, phenylbenzimidazole, and 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. The thing etc. can be mentioned.

  Among the light-emitting materials, materials that emit 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, and polyfluorene derivatives. Among these, as a material that emits green light, polymer materials such as polyparaphenylene vinylene derivatives and polyfluorene derivatives are preferable.

  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, as the material that emits red light, 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.

  The organic EL unit 16 may further include a predetermined functional layer as necessary. For example, an electron transport layer, a hole transport layer, a hole injection layer, or the like may be provided between the cathode 14 and the anode 18.

An example of the layer structure that the organic EL element 10 can take is shown below.
(A) Cathode / electron injection layer / light emitting layer / hole injection layer / anode (b) Cathode / electron injection layer / electron transport layer / light emitting layer / hole injection layer / anode (c) Cathode / electron injection layer / light emission Layer / hole transport layer / hole injection layer / anode (d) cathode / electron injection layer / electron transport layer / light emitting layer / hole transport layer / hole injection layer / anode (e) cathode / electron injection layer / light emission Layer / anode (f) cathode / electron injection layer / electron transport layer / emission layer / anode (g) cathode / emission layer / anode (h) cathode / emission layer / hole injection layer / anode (i) cathode / emission layer / Hole transport layer / hole injection layer / anode (Here, the symbol “/” indicates that the layers sandwiching the symbol “/” are adjacently stacked. The same applies hereinafter.) Organic of this embodiment The EL element 10 may have two or more light emitting layers 162.

(Hole injection layer)
Examples of the hole injection material constituting the hole injection layer include oxides such as vanadium oxide, molybdenum oxide, ruthenium oxide, and aluminum oxide, phenylamine compounds, starburst amine compounds, phthalocyanine compounds, amorphous carbon, Examples thereof include polyaniline and polythiophene derivatives.

  The thickness of the hole injection layer is appropriately set in consideration of electrical characteristics and easiness of film formation, and is, for example, 1 nm to 1 μm, preferably 2 nm to 500 nm, more preferably 5 nm to 200 nm. is there.

(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 And 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 thickness of the hole transport layer is appropriately set in consideration of the electrical characteristics and the ease of film formation, and is, for example, 1 nm to 1 μm, preferably 2 nm to 500 nm, more preferably 5 nm to 200 nm. It is.

(Electron transport layer)
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, and the like 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.

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

[anode]
When the light emitted from the light emitting layer 162 is emitted through the anode 18 as in the organic EL element 10, an electrode having translucency with respect to visible light is used for the anode 18. As the electrode having translucency, a thin film of metal oxide, metal sulfide, metal or the like having high electrical conductivity can be used, and an electrode having high light transmittance is preferably used. Specifically, a thin film made of indium oxide, zinc oxide, tin oxide, indium tin oxide (ITO), indium zinc oxide (IZO), gold, platinum, silver, copper, etc. is used. Among these, ITO, A thin film made of IZO or tin oxide is preferably used. As the anode 18, an organic transparent conductive film such as polyaniline or a derivative thereof, polythiophene or a derivative thereof may be used.

  The thickness of the anode 18 can be appropriately selected in consideration of light transmittance, electric resistance, and the like, and is, for example, 10 nm to 10 μm, preferably 20 nm to 1 μm, and more preferably 50 nm to 500 nm. .

[Method of manufacturing organic EL element]
Next, as illustrated in FIG. 1, an example of a method for manufacturing the organic EL element 10 in a form in which the organic EL unit 16 has a stacked structure of the electron injection layer 161 and the light emitting layer 162 will be described.

  As shown in FIG. 2, the method for manufacturing an organic EL element includes a step S10 for forming an electrode layer, a step S12 for forming an organic EL portion, and a step S14 for forming an anode. Hereinafter, each process will be described. Hereinafter, the step S10 for forming the electrode layer, the step S12 for forming the organic EL portion, and the step S14 for forming the anode are referred to as an electrode layer forming step S10, an organic EL portion forming step S12, and an anode forming step S14, respectively.

<Electrode layer forming step>
In the electrode layer forming step S10, the electrode layer 20 is formed on the substrate 12 as shown in FIG. The material of the electrode layer 20 is a material for forming the n-type semiconductor region 14a by being modified. An example of the material of the electrode layer 20 is the metal material exemplified as the cathode material in the description of the cathode 14. The electrode layer 20 is formed by, for example, an ink jet printing method, a screen printing method, a vacuum vapor deposition method, a sputtering method, or the like. Among these, it is preferable to form the electrode layer 20 by a vacuum vapor deposition method or a sputtering method.

<Organic EL part formation process>
In the organic EL part forming step S <b> 12, the organic EL part 16 is formed on the electrode layer 20. As shown in FIG. 2, the organic EL part forming step S12 includes a step of forming an electron injection layer (hereinafter referred to as “electron injection layer formation step”) S12A and a step of forming a light emitting layer (hereinafter referred to as “light emission”). S12B ”(referred to as“ layer forming step ”).

(Electron injection layer forming process)
In the electron injection layer forming step S <b> 12 </ b> A, the electron injection layer 161 is formed on the electrode layer 20. In this step S12A, the electron injection layer 161 is formed using a solvent or dispersion medium capable of modifying at least the surface portion of the electrode layer 20 and a coating liquid (for example, ink) containing the material for the electron injection layer 161 described above. . The solvent or dispersion medium capable of modifying at least the surface portion of the electrode layer 20 can modify all of the electrode layer 20 including the surface portion even if it can modify only the surface portion of the electrode layer 20. It may be. Examples of the solvent or dispersion medium that can modify at least the surface portion of the electrode layer 20 include a polar solvent or a polar dispersion medium. Specifically, examples of the solvent or dispersion medium that can modify the electrode layer 20 include alcohols, ethers, esters, nitrile compounds, nitro compounds, halogenated alkyls, aryl halides, and thiols. , Sulfides, sulfoxides, thioketones, amides, carboxylic acids and the like. Among these, solvents having a solubility of 9.3 or more are preferable, and alcohols are more preferable. Examples of the alcohols include methanol, ethanol, 2-propanol, 1-butanol, t-butyl alcohol, 1,2-ethanediol and the like.

  Application methods include spin coating, ink jet printing, slit coating, micro gravure coating, gravure coating, bar coating, roll coating, wire bar coating, spray coating, screen printing, flexographic printing. And offset printing method and nozzle printing method.

  As described above, if the electron injection layer 161 is formed using a coating liquid containing a solvent or dispersion medium capable of modifying at least the surface portion of the electrode layer 20, at least the electrode layer 20 in the formation process of the electron injection layer 161 is formed. The surface portion is modified, and as shown in FIG. 4, the cathode 14 in which the n-type semiconductor region 14a is formed is obtained. Therefore, in the electrode layer forming step S12A, the electron injection layer 161 is formed and the n-type semiconductor region 14a is formed. Therefore, in the present embodiment, the electron injection layer forming step S12A is also a step of forming the n-type semiconductor region 14a. Since the cathode 14 including the n-type semiconductor region 14a is formed by modifying at least a part of the electrode layer 20, the electron injection layer forming step S12A can be a part of the step of forming the cathode 14. . At this time, the unmodified portion of the electrode layer 20 becomes the metal region 14b. In the electron injection layer forming step S12A, when the entire electrode layer 20 is modified, the cathode 14 not having the metal region 14b but having only the n-type semiconductor region 14a is formed.

  4 shows a form in which an n-type semiconductor region 14a is formed on the surface portion of the electrode layer 20 shown in FIG. That is, the cathode 14 including the metal region 14b and the n-type semiconductor region 14a is illustrated.

  In the present specification, the “electrode layer” means a layer corresponding to a cathode (a layer to be a cathode) in the description of the method for manufacturing an organic EL element, and a layer before being modified. The “cathode” means a component included in the organic EL element manufactured by the method for manufacturing the organic EL element, and formed by modifying at least a part of the electrode layer. .

(Light emitting layer forming step)
In the light emitting layer forming step S12B, the light emitting layer 162 is formed on the electron injection layer 161. The light emitting layer 162 is formed by, for example, a coating method, a vacuum deposition method, a sputtering method, or the like, and is preferably formed by a coating method from the viewpoint of simplicity of the process. Examples of the coating method include the coating methods exemplified in the above-described electron injection layer forming step S12A.

  When the light emitting layer 162 is formed by a coating method, it is preferable to form the light emitting layer 162 using a coating liquid (for example, ink) that hardly dissolves the electron injection layer 161.

  Such a coating liquid includes a material that becomes the light emitting layer 162 and a solvent or a dispersion medium. For example, when the electron injection layer 161 is made of a material that dissolves in a polar solvent such as alcohols, it is preferable to use a nonpolar solvent or a nonpolar dispersion medium in which the electron injection layer 161 is difficult to dissolve. Or, as a dispersion medium, for example, a chlorinated solvent such as chloroform, methylene chloride or dichloroethane, an ether solvent such as tetrahydrofuran, an aromatic hydrocarbon solvent such as toluene or xylene, a ketone solvent such as acetone or methyl ethyl ketone, or ethyl acetate And ester solvents such as butyl acetate and ethyl cellosolve acetate, and aromatic hydrocarbon solvents are preferred.

(Anode formation process)
In the anode forming step S <b> 14, the anode 18 is formed on the light emitting layer 162. The anode 18 is formed by, for example, spin coating, inkjet coating, screen printing, flexographic printing, offset flat printing, spray coating, nozzle printing, vacuum deposition, sputtering, ion plating, plating, or the like. It is formed.

  The manufacturing method of the organic EL element is a manufacturing method in the case where the organic EL portion 16 has a laminated structure including the electron injection layer 161 and the light emitting layer 162. As described above, the organic EL unit 16 may have a layer other than the electron injection layer 161 and the light emitting layer 162 (for example, an electron transport layer, a hole transport layer, a hole injection layer, and the like). In the form in which the organic EL unit 16 includes layers other than the electron injection layer 161 and the light emitting layer 162, corresponding layers may be formed in order from the electrode layer 20 side. The layers other than the electron injection layer 161 and the light emitting layer 162 can be formed by a coating method, a vacuum deposition method, a sputtering method, an ion plating method, or the like.

  The organic EL element 10 manufactured by the manufacturing method shown in the flowchart of FIG. 2 is an inversely stacked organic EL element 10 in which the cathode 14 is positioned on the substrate 12 side with respect to the anode 18. In the manufacturing method described above, a metal material that becomes an n-type semiconductor by being modified is used as the material of the electrode layer 20. In the step of forming the electron injection layer 161 on the electrode layer 20, at least the electrode layer 20 is formed. The cathode 14 including the n-type semiconductor region 14a is formed by modifying the surface portion. Therefore, it is possible to realize the reverse stacked organic EL element 10 that can be driven with a low driving voltage.

  This will be described in comparison with a case where aluminum, which is a material that does not form an n-type semiconductor even if modified, is used as a cathode material in contact with the organic EL portion 16.

  Since aluminum has a high visible light reflectivity, in the field of the organic EL element 10, it is often used as a cathode material when light is emitted from the anode 18 side. However, aluminum is easily modified by being exposed to a polar solvent, and easily forms an insulating region. Therefore, when the aluminum is used as a cathode material in contact with the organic EL portion in the reverse stacked organic EL element, the aluminum is modified in the manufacturing process, and the organic EL portion is in contact with the insulating region. As a result, the electron injection property from the cathode to the light emitting layer is lowered, and the drive voltage of the organic EL element is increased.

  On the other hand, in the method of manufacturing the organic EL element of the present embodiment, a metal material that is modified to become an n-type semiconductor is used as the material of the electrode layer 20, and the organic EL portion 16 is being formed (FIG. 1). In the element configuration illustrated in FIG. 5, at least the surface portion of the electrode layer 20 is modified to form the n-type semiconductor region 14a during the formation of the electron injection layer 161). Therefore, in the manufactured organic EL element 10, the organic EL portion 16 (the electron injection layer 161 in the element configuration illustrated in FIG. 1) is in contact with the n-type semiconductor region 14a. Therefore, the organic EL element manufacturing method of the present embodiment can manufacture the organic EL element 10 capable of realizing a low driving voltage.

  Since a metal material that becomes an n-type semiconductor by being modified is used as the material of the electrode layer 20, a layer in contact with the electrode layer 20 in the organic EL portion 16 can be formed by a coating method as illustrated. . For example, in the configuration shown in FIG. 1, the electron injection layer 161 can be formed on the electrode layer 20 by a coating method. Furthermore, the light emitting layer 162 can also be formed on the electron injection layer 161 by a coating method. The coating method can be carried out, for example, while transporting the substrate 12, so that it is easy to improve the productivity of the reverse stacked organic EL element 10. Furthermore, a roll-to-roll method that is advantageous for improving the productivity of the organic EL element 10 can be applied by adopting a coating method.

  When forming a layer directly formed on the electrode layer 20 (for example, the electron injection layer 161) by a coating method, a solvent or a dispersion medium capable of modifying at least the surface portion of the electrode layer 20 is used. The n-type semiconductor region 14 a can be formed by modifying at least the surface portion of the electrode layer 20. In this case, since the formation process of the layer directly formed on the electrode layer 20 also serves as a modification process of the electrode layer 20, high productivity can be realized.

(Modification)
FIG. 5 is a schematic view of an organic EL element 10A that is a modification of the organic EL element 10 shown in FIG. The organic EL element 10 </ b> A is different from the configuration of the organic EL element 10 in that it has a cathode 22 having a first cathode 221 and a second cathode 222 instead of the cathode 14. The configuration of the organic EL element 10 other than the above differences is the same as that of the organic EL element 10. Therefore, a modified example will be described focusing on the differences.

  The first cathode 221 includes a metal material that becomes an n-type semiconductor by being modified in the same manner as the cathode 14 of the organic EL element 10. An example of the metal material for the first cathode 221 is the same as the metal material illustrated for the cathode 14. The first cathode 221 includes an n-type semiconductor region 221a on the surface portion (portion on the organic EL portion 16 side). An example of the thickness of the first cathode 221 is 0.1 nm to 200 nm. In FIG. 5, the first cathode 221 exemplifies a form including the n-type semiconductor region 221a and the metal region 221b. However, as in the case of the cathode 14, the entire first cathode 221 is the n-type semiconductor region 221a. May be.

  The second cathode 222 is disposed between the substrate 12 and the first cathode 221. The thickness of the second cathode 222 is preferably 0.1 nm to 300 nm, for example. The second cathode 222 has a higher reflectance than the first cathode 221 with respect to visible light.

  Examples of the material of the second cathode 222 include aluminum (Al), silver (Ag), gold (Au), and chromium (Cr), or an alloy containing at least two of these metals. The second cathode 222 is preferably composed of Al or Ag among the exemplified metals.

  The organic EL element 10A is different from the flowchart shown in FIG. 6 in that an electrode layer forming step (electrode layer forming step) S20 is provided instead of the electrode layer forming step S10 shown in FIG. Other than that, it is manufactured by the same manufacturing method as in the case of the organic EL element 10. Therefore, as a method for manufacturing the organic EL element 10 </ b> A, the electrode layer forming step S <b> 20 which is mainly the difference will be described.

  In the electrode layer forming step S20, a lower layer (first layer) is formed on the substrate 12 (hereinafter referred to as “lower layer forming step”) S20A, and an upper layer (second layer) is formed on the lower layer. (Hereinafter referred to as “upper layer forming step”) S20B. Thereby, in the electrode layer formation step S20, as shown in FIG. 7, the electrode layer 24 having the lower layer 241 and the upper layer 242 is formed.

  The electrode layer 24 is an electrode layer having a two-layer structure that becomes the cathode 22 by modifying at least a part (for example, a surface portion) of the upper layer 242. Specifically, the upper layer 242 is a layer that should become the first cathode 221 by modifying at least a part (for example, a surface portion) of the upper layer 242. The lower layer 241 is a layer corresponding to the second cathode 222 in the description of the method for manufacturing the organic EL element. The lower layer 241 is not modified. That is, in the description of the method for manufacturing the organic EL element, the second cathode 222 is referred to as the lower layer 241 for convenience.

  In the lower layer forming step S <b> 20 </ b> A, the lower layer 241 as the second cathode 222 is formed on the substrate 12. The lower layer 241 can be formed by the same method as that for forming the electrode layer 20 except that the material for the second cathode 222 is used. In order to realize the above-described reflectance relationship between the first cathode 221 and the second cathode 222, the material for the lower layer 241 has a higher reflectance for visible light than the material for the upper layer 242; The reflectance for the lower layer 241 is, for example, 70% or more with respect to visible light, and more preferably 90% or more. In the upper layer formation step S <b> 20 </ b> B, an upper layer 242 that becomes the first cathode 221 is formed on the lower layer 241. The upper layer 242 can form the upper layer 242 in the same manner as the lower layer 241 except that the material for the second cathode 222 is used. Since the material for the second cathode 222 can be the same as the material of the electrode layer 20, the upper layer forming step S20B can be the same as the electrode layer forming step S10.

  After performing said electrode layer formation process S20, similarly to the case of organic EL element 10, organic EL element 10A is manufactured by implementing organic EL part formation process S12 and anode formation process S14.

  In the manufacture of the organic EL element 10A, an upper layer 242 including a metal material that is modified to become an n-type semiconductor is formed. Therefore, in the organic EL part forming step S12, if the electron injection layer 161 is formed on the upper layer 242 by the same method as that for the organic EL element 10, at least the surface part of the upper layer 242 is modified, and n A first cathode 221 including the type semiconductor region 14a is formed. Therefore, in the method for manufacturing the organic EL element 10A, the electrode layer forming step S12A includes a modification step of the electrode layer 24 (more specifically, the upper layer 242).

  In the organic EL element 10A manufactured by the above manufacturing method, the first cathode 221 in contact with the organic EL unit 16 in the cathode 22 includes the n-type semiconductor region 14a. Therefore, the organic EL element 10A and the manufacturing method thereof have at least the same effects as the organic EL element 10 and the manufacturing method thereof.

  In the manufacturing method of the organic EL element 10A, after forming the lower layer 241 as the second cathode 222, the upper layer 242 to be the first cathode 221 is formed, and the material for the lower layer 241 is the material for the upper layer 242. It has a higher reflectance for visible light than the above materials. Therefore, in the manufacturing method of this modification, the organic EL element 10 </ b> A having the cathode 22 in which the first cathode 221 is stacked on the second cathode 222 having a higher reflectance than the first cathode 221 is manufactured. Therefore, the light emitted from the light emitting layer 162 is easily reflected by the cathode 22. As a result, the light emission efficiency of the organic EL element 10A that outputs light from the anode 18 side is improved. That is, the organic EL element manufacturing method described in this modification can manufacture the organic EL element 10A with improved light emission efficiency while realizing a low driving voltage.

  Hereinafter, the verification experiment of the effect of the organic EL element demonstrated by the said embodiment and modification is demonstrated.

[Verification Experiment 1]
In verification experiment 1, it was verified that the electron injection characteristics were improved by using a metal material that was modified to be an n-type semiconductor as a cathode material. In this verification experiment 1, an experimental element having the following element configuration (hereinafter referred to as experimental element E1) was used.
Substrate / lower electrode / electron injection layer / light emitting layer / electron injection layer / upper electrode

  As the experimental element E1 having the above configuration, an element using Zn as a material for the lower electrode (hereinafter referred to as “experimental element E1a”) and an element using Al as the material for the lower electrode (hereinafter referred to as “experimental element”). For the purpose of manufacture).

(Method for manufacturing experimental element E1a)
In the experimental element E1a, a glass plate having a thickness of 0.7 mm was prepared as a substrate. Further, 2 mg of ionic polymer was mixed with 1 ml of methanol to prepare a coating liquid containing the ionic polymer (hereinafter referred to as “coating liquid α”). Furthermore, polymer light emitting material P1 and xylene were mixed to prepare a light emitting layer forming composition C containing 1.3% by weight of polymer light emitting material P1.

  Next, a thin film (Zn film) having a thickness of 50 nm and made of Zn was formed as a lower electrode on the substrate (glass plate) using a load lock type sputtering apparatus. A coating film is obtained by spin coating the coating liquid α containing the ionic polymer on the Zn film in a nitrogen atmosphere, and the coating film is heated and dried at 130 ° C. for 10 minutes in a nitrogen atmosphere. Thus, an electron injection layer having a thickness of 30 nm was obtained.

  On the electron injection layer obtained above, the light emitting layer forming composition C was applied by a spin coating method in a nitrogen atmosphere to obtain a coating film having a thickness of 80 nm. The substrate provided with this coating film was heated in a nitrogen atmosphere at 190 ° C. for 60 minutes to evaporate the solvent, and then naturally cooled to room temperature to obtain a substrate on which a light emitting layer was formed.

  A coating film is obtained by spin-coating a coating liquid α containing the ionic polymer in a nitrogen atmosphere on the light-emitting layer of the substrate on which the light-emitting layer is formed. The mixture was heated and dried at 130 ° C. for 10 minutes to obtain an electron injection layer having a thickness of 30 nm. On the electron injection layer, a thin film (Al film) made of Al having a thickness of 80 nm was formed as an upper electrode by a vacuum deposition method, and an experimental element E1a was obtained.

  As understood from the above manufacturing method, a coating solution containing methanol which is a polar solvent is used for forming the electron injection layer. Therefore, when the electron injection layer is formed on the Zn film in the manufacturing process, the surface portion of the Zn film is modified, and the n-type semiconductor region is formed on the surface portion of the Zn film. On the other hand, since the upper electrode is formed by a vacuum deposition method, the electron injection layer side of the upper electrode is not modified.

(Method for manufacturing experimental element E1b)
In the manufacturing method of the experimental element E1a, the experimental element E1b was manufactured by the same method as the manufacturing method of the experimental element E1a except that the material of the lower electrode was changed to Al. Also in the experimental element E1b, a coating solution containing methanol, which is a polar solvent, is used for forming the electron injection layer. Therefore, in the manufacturing process, when the electron injection layer is formed on the thin film (Al film) made of Al of the lower electrode having a thickness of 50 nm, the surface portion of the Al film of the lower electrode is modified, and the Al of the lower electrode is modified. An insulating region is formed on the surface of the film.

(Electron injection experiment)
When applying a voltage from -3V to + 10V between the lower electrode and the upper electrode of the experimental element E1a (first measurement) and when applying a voltage from + 3V to -10V (second measurement) The state of electron injection into the experimental element E1a was evaluated based on the current flowing through the experimental element E1a. The experimental results were as shown in FIG. In FIG. 8, the horizontal axis represents voltage (V), and the vertical axis represents current (A).

  In FIG. 8, a white square mark indicates a current value when a voltage of −3 V to +10 V is applied between the lower electrode and the upper electrode as a first measurement, and a white diamond mark indicates the second measurement. As a measurement, the current value when a voltage of +3 V to −10 V is applied between the lower electrode and the upper electrode is shown. In FIG. 8, from −3 V to 0 V in the first measurement and from 0 V to −10 V in the second measurement indicate electron injectability from the lower electrode, and from 0 V to +10 V in the first measurement. From +3 V to 0 V in the second measurement, electron injectability from the upper electrode is shown.

  Similarly, when a voltage is applied from −5 V to +10 V between the lower electrode and the upper electrode of the experimental element E1b (first measurement) and when a voltage is applied from +5 V to −10 V (second measurement). In contrast, the state of electron injection into the experimental element E1b was evaluated based on the current flowing through the experimental element E1b. The experimental results were as shown in FIG. In FIG. 9, the horizontal axis represents voltage (V), and the vertical axis represents current (A).

  In FIG. 9, a white square mark indicates a current value when a voltage of −5 V to +10 V is applied between the lower electrode and the upper electrode as the first measurement. The white diamond mark indicates the current value when a voltage of +5 V to −10 V is applied between the lower electrode and the upper electrode as the second measurement. As in the case of FIG. 8, in FIG. 9, from −5 V to 0 V in the first measurement and from 0 V to −10 V in the second measurement, the electron injectability from the lower electrode is shown. From 0 V to +10 V in the measurement and from +5 V to 0 V in the second measurement, the electron injectability from the upper electrode is shown.

  As shown in FIG. 8, in the experimental element E1a using Zn as the material for the lower electrode, the electron injecting property from the lower electrode and the electron injecting property from the upper electrode made of Al are substantially the same. confirmed. On the other hand, as shown in FIG. 9, in the experimental element E1b using Al as the material for the lower electrode, the electron injecting property from the lower electrode is lower than the electron injecting property from the upper electrode made of Al. It was confirmed that The result of the experimental element E1b is considered to be because an insulating region is formed on the surface portion of the lower electrode.

  Therefore, by using Zn that is modified to become an n-type semiconductor as the material for the lower electrode, the same level of electron injection from the upper electrode (Al film) whose surface portion on the electron injection layer side is not modified is used. Can be realized from the lower electrode side. That is, it was verified that the electron injection property can be improved by using a metal material that is modified into a cathode material in contact with the organic EL portion and becomes an n-type semiconductor.

[Verification experiment 2]
In verification experiment 2, an organic EL element was manufactured, and the effect of using a metal material that was modified to become an n-type semiconductor as a cathode material was verified. In this verification experiment 2, an experimental element having the following element configuration (hereinafter referred to as experimental element E2) was used. As understood from the following configuration, the experimental element E2 is an organic EL element.
Substrate / cathode / electron injection layer / light emitting layer / hole transport layer / hole injection layer / anode

  As the experimental element E2 having the above configuration, an element using Zn as a cathode material (hereinafter referred to as experimental element E2a) and an element using Al as a cathode material (hereinafter referred to as experimental element E2b) are manufactured. did.

(Method for manufacturing experimental element E2a)
For the production of the experimental element E2a As a substrate, a glass plate having a thickness of 0.7 mm was prepared as in the case of the experimental element E1a. Furthermore, a coating solution α was prepared as a coating solution for forming the electron injection layer, as in the case of the experimental element E1a. Further, as a composition for forming a light emitting layer for forming a light emitting layer, a composition C for forming a light emitting layer was prepared as in the case of the experimental element E1a.

  In the manufacturing method of the experimental element E2a, in order to form the hole transport layer, the polymer compound P2 was dissolved in xylene at a concentration of 0.6% by weight to prepare a xylene solution containing the polymer compound P2. Furthermore, in order to form a hole injection layer, the polymer compound P3 was dissolved in a solvent to prepare a suspension of the polymer compound P3.

  Next, a 50 nm-thick Zn film was formed on the substrate (glass substrate) using a load-lock sputtering apparatus. A coating film is obtained by spin coating the coating liquid α containing the ionic polymer on the Zn film in a nitrogen atmosphere, and the coating film is heated and dried at 130 ° C. for 10 minutes to obtain a thickness. An electron injection layer having a thickness of 10 nm was obtained.

  On the electron injection layer obtained above, the light emitting layer forming composition C was applied by a spin coating method in a nitrogen atmosphere to obtain a coating film having a thickness of 80 nm. The substrate provided with this coating film was heated in a nitrogen atmosphere at 190 ° C. for 60 minutes to evaporate the solvent, and then naturally cooled to room temperature to obtain a substrate on which a light emitting layer was formed.

  On the light emitting layer, a xylene solution containing the polymer compound P2 is applied in the air by a spin coating method, and the coating film is dried by heating at 180 ° C. for 60 minutes in a nitrogen atmosphere to form a hole having a thickness of 20 nm. A transport layer was obtained.

  On the hole transport layer, a suspension of the polymer compound P3 is applied by spin coating in the air, and heated at 170 ° C. for 15 minutes in a nitrogen atmosphere to obtain a hole injection layer having a thickness of 60 nm. It was.

  A film (Au film) made of Au having a thickness of 20 nm was formed as an anode on the hole injection layer by a vacuum deposition method to obtain an experimental element E2a having a light emitting portion size of 2 mm × 2 mm.

  As understood from the above manufacturing method, a coating solution containing methanol which is a polar solvent is used for forming the electron injection layer. Therefore, in the manufacturing process, when the electron injection layer is formed on the Zn film, the surface portion of the Zn film is modified, so that a cathode having an n-type semiconductor region is formed on the surface portion.

(Method for manufacturing experimental element E2b)
In the manufacturing method of the experimental element E2a, the experimental element E2b was manufactured by the same method as the manufacturing method of the experimental element E2a, except that the cathode material was changed to Al. Also in the experimental element E2b, a coating solution containing methanol which is a polar solvent is used for forming the electron injection layer. Therefore, in the manufacturing process, when the electron injection layer is formed on the Al film, the surface portion of the Al film is modified, so that a cathode having an insulating region is formed on the surface portion.

(Luminescence test)
While changing the voltage applied between the cathode and anode of each of the experimental element E2a and the experimental element E2b, the experimental element E2a and the experimental element E2b were caused to emit light, and the luminance and current density were measured. The luminance was measured using light emitted from the anode side, and the current density was calculated from the current flowing through the experimental element E2a and the experimental element E2b and the area of the light emitting part. The measurement result of the luminance was as shown in FIG. 10, and the measurement result of the current density was as shown in FIG. In FIG. 10, the horizontal axis represents voltage (V), and the vertical axis represents luminance (cd / m ² ). In FIG. 6, the horizontal axis represents voltage (V), and the vertical axis represents current density (mA / cm ² ).

As shown in FIG. 10, with the same drive voltage, the experimental element E2a was able to achieve higher luminance than the experimental element E2b. As shown in FIG. 11, at the same current density, the experimental element E2a was able to realize a lower drive voltage than the experimental element E2b. For example, when the current density is 80 mA / cm ² , the driving voltage of the experimental element E2a is about 8V, and the driving voltage of the experimental element E2b is about 10V. That is, when the current density is 80 mA / cm ² , the driving voltage of the experimental element E2a is about 2V lower than that of the experimental element E2b.

  In other words, a metal material that is modified to form an n-type semiconductor (Zn in Verification Experiment 2) is used as the cathode material, and a metal material that is modified to form an insulating region (Al in Verification Experiment 2) is used. It was verified that the drive voltage of the organic EL element can be reduced as compared with the case of the above.

[Verification Experiment 3]
An experimental element E3a in which a Zn film having a thickness of 50 nm was formed on this substrate using a load lock type sputtering apparatus using a 0.7 mm-thick glass plate as a substrate was manufactured. Similarly, a 0.7 nm thick glass plate is used as a substrate, and a 50 nm thick Al film is formed on the substrate using a load lock type sputtering apparatus, and then a 2 nm thick Zn film is formed on the Al film. Thus, an experimental element E3b was manufactured. In the manufacture of the experimental element E3b, the experimental elements E3c, E3d, E3e, E3f are the same as the manufacturing method of the experimental element E3b, except that the thickness of the Zn film is changed to 5 nm, 10 nm, 15 nm, and 25 nm. Manufactured.

  The reflectances of the experimental elements E3a to E3f when light was incident from the Zn film side were measured using an optical thin film measuring system (Film Tek 3000) manufactured by Scientific Computing International. The experimental results were as shown in FIG. As shown in FIG. 12, it was verified that the laminated structure of the Al film and the Zn film has a higher reflectance than the experimental element E3a in which the Zn film is formed as a single layer on the substrate.

[Verification Experiment 4]
In the verification experiment 4, the operation effect of the organic EL element when the cathode has a laminated structure of the second cathode and the first cathode and the second cathode has a higher reflectivity with respect to visible light than the first cathode was verified.

In the verification experiment 4, an experimental element (hereinafter referred to as an experimental element E4) which is an organic EL element having the following element configuration was used.
Substrate / cathode / electron injection layer / light emitting layer / hole transport layer / hole injection layer / anode

In verification experiment 4, an experimental element (hereinafter referred to as experimental element E5), which is an organic EL element having the following element configuration, was also used.
Substrate / second cathode / first cathode / electron injection layer / light emitting layer / hole transport layer / hole injection layer / anode

As the experimental element E5 having the above-described configuration, elements having a first cathode thickness of 2 nm, 5 nm, 10 nm, and 15 nm (hereinafter, experimental elements E5a, E5b, E5c, and E5d) were manufactured.

(Method for manufacturing experimental element E4)
The experimental element E4 was manufactured in the same manner as the experimental element E2a except that the thickness of the light emitting layer was changed to 70 nm and the thickness of the hole injection layer was changed to 65 nm. Therefore, when the electron injection layer is formed on the Zn film in the manufacturing process, the surface portion of the Zn film is modified, and the n-type semiconductor region is formed on the surface portion of the Zn film.

(Method for manufacturing experimental element E5a)
For the production of the experimental element E5a As a substrate, a glass plate having a thickness of 0.7 mm was prepared as in the case of the experimental element E1a. Furthermore, a coating solution α was prepared as a coating solution for forming the electron injection layer, as in the case of the experimental element E1a. Further, as a composition for forming a light emitting layer for forming a light emitting layer, a composition C for forming a light emitting layer was prepared as in the case of the experimental element E1a.

  In the manufacturing method of the experimental element E5a, as in the case of the experimental element E2a, in order to form the hole transport layer, the high molecular compound P2 was dissolved in xylene at a concentration of 0.6% by weight. A xylene solution containing P2 was prepared. Furthermore, in order to form the hole injection layer, a suspension of the polymer compound P3 was prepared as in the case of the experimental element E2a.

  Next, an Al film having a thickness of 50 nm is formed as a second cathode on the substrate (glass substrate) by using a load lock type sputtering apparatus, and then a Zn film having a thickness of 2 nm is formed on the Al film. did. Thereafter, an experimental element E5a was obtained in the same manner as in the manufacturing method of the experimental element E4. In the manufacturing process of the experimental element 5a, when the electron injection layer is formed on the Zn film, the surface portion of the Zn film is modified, so that a cathode having an n-type semiconductor region is formed on the surface portion.

(Method for manufacturing experimental elements E5b to E5d)
The experimental elements E5b to E5d are the same as the manufacturing method of the experimental element E5a, except that the thickness of the Zn film formed on the 50 nm thick Al film as the second cathode is 5 nm, 10 nm, and 15 nm. Manufactured. Therefore, in the manufacturing process of each of the experimental elements E5b to E5d, when the electron injection layer is formed on the Zn film, the surface portion of the Zn film is modified, so that a cathode having an n-type semiconductor region is formed on the surface portion. Is formed.

(Luminescence test)
While changing the voltage applied between the cathode and the anode of each of the experimental element E4 and the experimental elements E5a to 5d, the experimental element E4 and the experimental elements E5a to 5d emit light, and the experimental element E4 and the experimental element The luminous efficiency of each of the elements E5a to 5d was calculated. Specifically, the luminance and current density were obtained in the same manner as in the verification experiment 2, and the luminous efficiency was calculated based on them. The experimental results are as shown in FIG. In FIG. 13, the horizontal axis indicates voltage (V), and the vertical axis indicates light emission efficiency (cd / A).

  As shown in FIG. 13, the experimental elements E5a to E5d laminated with Al have better luminous efficiency than the experimental element E4 using only Zn as the cathode material. This is presumably because more light is reflected by the second cathode made of Al. Therefore, as in the organic EL element 10A shown in FIG. 5, by forming the cathode 22 having a laminated structure of the second cathode 222 and the first cathode 221 having a higher reflectance than the first cathode 221, low driving is achieved. It is possible to manufacture an organic EL element that can improve luminous efficiency while realizing voltage.

  The various embodiments and examples of the present invention have been described above. However, the present invention is not limited to the various embodiments and examples described above, and various modifications can be made without departing from the spirit of the present invention.

  In the method of manufacturing the organic EL element illustrated in FIGS. 2 and 6, the electrode layer is modified by using a solvent or a dispersion medium when the layer that the organic EL unit has and is in contact with the electrode layer is formed by a coating method. However, as long as the electrode layer can be modified, the modification method is not particularly limited.

  The modification of the electrode layer may be performed after the step of forming the electrode layer, and may be performed at the time of forming the organic EL portion or before the formation of the organic EL portion. .

  The organic EL element may be configured to emit light from the substrate side as long as the cathode has a light-transmitting property and includes a material that is modified to become an n-type semiconductor.

  DESCRIPTION OF SYMBOLS 10,10A ... Organic EL element, 12 ... Board | substrate, 14 ... Cathode, 14a ... N-type semiconductor region, 16 ... Organic EL part, 161 ... Electron injection layer, 162 ... Light emitting layer, 18 ... Anode, 20 ... Electrode layer, 22 ... cathode, 24 ... electrode layer, 241 ... lower layer (first layer), 242 ... upper layer (second layer).

Claims (7)

Forming an electrode layer including a metal material which becomes an n-type semiconductor by being modified on a substrate;
Forming an organic EL part including a light emitting layer on the electrode layer;
Forming an anode on the organic EL part;
With
After the step of forming the electrode layer, a cathode including an n-type semiconductor region is formed by modifying the electrode layer.
Manufacturing method of organic EL element. The step of forming the organic EL part includes:
Forming an electron injection layer on the electrode layer;
Forming the light emitting layer on the electron injection layer;
Have
In the step of forming the electron injection layer, the electron injection layer is formed by a coating method using a coating liquid containing a solvent or a dispersion medium capable of modifying at least the surface portion of the electrode layer.
The manufacturing method of the organic EL element of Claim 1. The metal material is zinc, titanium, or indium.
The manufacturing method of the organic EL element of Claim 1 or 2. The anode has translucency for visible light,
The manufacturing method of the organic EL element as described in any one of Claims 1-3. In the step of forming the electrode layer, the first layer and the second layer are formed in order from the substrate side,
The material of the second layer is the metal material,
The material of the first layer is a metal material having a higher reflectance for visible light than the metal material constituting the second layer.
The manufacturing method of the organic EL element of Claim 4. The material of the first layer is a metal material having a reflectance with respect to visible light of 70% or more.
The manufacturing method of the organic EL element of Claim 5. The material of the first layer is aluminum or silver.
The manufacturing method of the organic EL element of Claim 6.

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