Method for manufacturing an organic light-emitting element, organic light-emitting element, and display device.

Abstract

The present invention provides a method for manufacturing organic light-emitting elements that have a low driving voltage and excellent luminous efficiency, enabling efficient production of such elements. [Solution] A method for manufacturing an organic light-emitting element having a stacked structure in which a first electrode, a first organic compound layer, an intermediate layer, a second organic compound layer, and a second electrode are stacked in this order. The method comprises the steps of forming a first organic compound layer, applying a liquid composition onto the first organic compound layer to form an intermediate layer with an average thickness of 3 nm to 30 nm, and forming a second organic compound layer on the intermediate layer, wherein either the first organic compound layer or the second organic compound layer includes a light-emitting layer, and the liquid composition includes a metal alkoxide containing a metal atom with a valency of 3 or higher, and a solvent.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing an organic light-emitting device, an organic light-emitting device, and a display device.

Background Art

[0002] An organic light-emitting device is an electronic device having a pair of electrodes composed of a first electrode and a second electrode, and an organic compound layer disposed between the pair of electrodes. By injecting electrons and holes (holes) from the pair of electrodes into the organic compound layer, respectively, a light-emitting organic compound in the organic compound layer can be activated from the ground state to the excited state. Then, when the excited organic compound returns to the ground state, excess energy can be released as light.

[0003] An organic light-emitting device is also called an organic electroluminescence device or an organic EL device. An organic light-emitting device can generally be manufactured by a dry process such as a so-called vacuum evaporation method in which materials for forming various functional layers such as an organic compound layer, an inorganic compound layer, and an electrode (layer) are thermally evaporated onto a substrate under high vacuum. On the other hand, it is difficult to perform uniform evaporation on a large-area substrate, and in recent years, a method for manufacturing an organic light-emitting device by a wet process such as a printing method has also been studied from the viewpoints of material utilization efficiency and manufacturing cost. In order to improve the performance of an organic light-emitting device, it is necessary to precisely stack a plurality of organic compound layers having different characteristics and physical properties, and thus, a technique for insolubilizing an organic compound layer has also been studied.

[0004] As a technique for insolubilizing an organic compound layer, a method has been proposed in which a liquid composition containing a conductive organic material having a crosslinkable reactive group is applied to a substrate and then heated to cause a crosslinking reaction to proceed and insolubilize (Patent Document 1). In addition, a method of forming a film made of a material insoluble in an organic solvent between organic compound layers to suppress mixing between adjacent organic compound layers has been described (Patent Documents 2 and 3).

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2015-12105 [Patent Document 2] Japanese Patent Publication No. 2005-129450 [Patent Document 3] Japanese Patent Publication No. 2006-302637 [Overview of the project] [Problems that the invention aims to solve]

[0006] The present inventors investigated the methods proposed in Patent Documents 1 to 3 and the various characteristics of organic light-emitting devices manufactured by these methods. As a result, it was found that the organic light-emitting device manufactured by the method proposed in Patent Document 1 has a high driving voltage because the organic compound layer contains crosslinking reactive groups that do not contribute to electrical conductivity.

[0007] Furthermore, the dispersion of the organic solvent-insoluble material (a composite of poly(3,4-ethylenedioxythiophene) and polystyrene sulfonic acid (PEDOT:PSS)) used in the method proposed in Patent Document 2 shows sedimentation of solid components after standing for several days. Therefore, it is necessary to continuously stir the dispersion during manufacturing, and variations in the resulting organic light-emitting elements are likely to occur, posing challenges in terms of productivity. Moreover, it was found that the organic light-emitting elements manufactured by the method proposed in Patent Document 3 did not necessarily have sufficiently insoluble organic compound layers, resulting in insufficient luminescence efficiency.

[0008] Therefore, an object of the present invention is to provide a method for manufacturing an organic light-emitting element that can efficiently produce an organic light-emitting element with a low driving voltage and excellent luminous efficiency. Another object of the present invention is to provide an organic light-emitting element with a low driving voltage and excellent luminous efficiency, and a display device using this organic light-emitting element. [Means for solving the problem]

[0009] In other words, the present invention provides a method for manufacturing an organic light-emitting element having a stacked structure in which a first electrode, a first organic compound layer, an intermediate layer, a second organic compound layer, and a second electrode are stacked in this order, comprising the steps of forming the first organic compound layer, applying a liquid composition onto the first organic compound layer to form the intermediate layer with an average thickness of 3 nm to 30 nm, and forming the second organic compound layer on the intermediate layer, wherein either the first organic compound layer or the second organic compound layer includes a light-emitting layer, and the liquid composition includes a metal alkoxide containing a metal atom with a valency of 3 or higher, and a solvent. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a method for manufacturing organic light-emitting elements that have a low driving voltage and excellent luminous efficiency, and an organic light-emitting element that has a low driving voltage and excellent luminous efficiency, and a display device using this organic light-emitting element. [Brief explanation of the drawing]

[0011] [Figure 1A] A schematic cross-sectional view showing an example of a pixel constituting the display device of the present invention. [Figure 1B] This is a schematic cross-sectional view showing one embodiment of the device for the present invention. [Figure 2] This is a schematic diagram showing another embodiment of the display device of the present invention. [Figure 3A] This is a schematic diagram showing an example of an imaging device. [Figure 3B] This is a schematic diagram illustrating an example of a portable device. [Figure 4A] This is a schematic diagram showing another embodiment of the display device of the present invention. [Figure 4B] This is a schematic diagram showing another embodiment of the display device of the present invention. [Figure 5A] This is a schematic diagram showing an example of a lighting device. [Figure 5B] This is a schematic diagram showing an example of a mobile object. [Figure 6A] It is a schematic diagram showing an example of a wearable device. [Figure 6B] It is a schematic diagram showing another example of a wearable device.

Mode for Carrying Out the Invention

[0012] Hereinafter, preferred embodiments will be given to explain the present invention in more detail. Physical property values are values at room temperature (25 ° C) unless otherwise specified. Further, the "average thickness" means the average thickness of each layer (film) in the region that emits light when a voltage is applied to the organic light-emitting element.

[0013] The present inventor has variously studied a method for efficiently manufacturing an organic light-emitting element having a low driving voltage and excellent luminous efficiency. As a result, it has been found that it is effective to adopt the configuration shown below, and the present invention has been achieved. That is, the method for manufacturing an organic light-emitting element of the present invention is a method for manufacturing an organic light-emitting element having a laminated structure in which a first electrode, a first organic compound layer, an intermediate layer, a second organic compound layer, and a second electrode are laminated in this order. The manufacturing method of the present invention includes a step of forming a first organic compound layer, a step of applying a predetermined liquid composition onto the first organic compound layer to form an intermediate layer having an average thickness of 3 nm or more and 30 nm or less, and a step of forming a second organic compound layer on the intermediate layer. The liquid composition contains a metal alkoxide containing a metal atom having a valence of 3 or more and a solvent. And either the first organic compound layer or the second organic compound layer contains a light-emitting layer.

[0014] The metal alkoxide in the liquid composition applied onto the first organic compound layer is hydrolyzed and polycondensed in the presence of water contained in air or the solvent contained in the liquid composition, and is converted into a so-called metalloxane compound having a repeating structure of metal atoms and oxygen atoms. The metalloxane compound is a compound having a three-dimensional network structure in which metal atoms having a valence of 3 or more and oxygen atoms are alternately bonded. The metalloxane compound may be composed only of metal atoms having a valence of 3 or more and oxygen atoms, or may have a functional group such as an alkyl group as shown in the following formula (1).

[0015] TIFF2026047164000001.tif41170(In the formula (1), M represents a metal atom with a valence of 3 or more, and R represents an alkyl group)

[0016] When a metal alkoxide containing a metal atom with a valence of 3 or more undergoes hydrolysis and polycondensation, a dense three-dimensional network structure is formed as the molecular weight increases, and an intermediate layer that is poorly soluble in the solvent is formed. The greater the valence of the metal atom constituting the metal alkoxide, the more reaction points for polycondensation, so the poor solubility (solvent resistance) of the formed intermediate layer is improved. By forming an intermediate layer with an average thickness of 3 nm or more, the solvent resistance of the first organic compound layer is improved, and mixing of the first organic compound layer and the second organic compound layer, which is likely to occur when forming the second organic compound layer, can be suppressed. As a result, the first organic compound layer and the second organic compound layer can be formed by clearly separating them from each other, and the functions of each layer can be fully exerted, improving the light emission efficiency of the obtained organic light-emitting device. Also, by forming an intermediate layer with an average thickness of 30 nm or less, an organic light-emitting device that can be driven at a low applied voltage equivalent to the case where no intermediate layer is provided can be obtained.

[0017] Moreover, the liquid composition containing the metal alkoxide and the solvent is less likely to have the solid content settle compared to a dispersion of a polymer compound such as PEDOT:PSS and can be stored in a uniform state for a long time. Therefore, in the manufacturing method of the present invention, it is not necessary to stir the liquid composition for forming the intermediate layer. Furthermore, variations in the properties of the formed intermediate layer and the obtained organic light-emitting device are unlikely to occur, so it is excellent in productivity.

[0018] <Organic Light-Emitting Device> The organic light-emitting element of the present invention has a laminated structure in which constituent layers including a first electrode, a first organic compound layer, a second organic compound layer, and a second electrode are stacked. The constituent layers further include an intermediate layer with an average thickness of 3 nm to 30 nm, which is placed between the first organic compound layer and the second organic compound layer. Either the first organic compound layer or the second organic compound layer includes an emissive layer. The intermediate layer contains a metalloxane compound that includes a metal atom with a valency of 3 or higher. The details of the organic light-emitting element of the present invention will be described below.

[0019] (Configuration of organic light-emitting diodes) An organic light-emitting element has a laminated structure in which multiple constituent layers are stacked. The multiple constituent layers include a first electrode, a first organic compound layer, a second organic compound layer, and a second electrode. The multiple constituent layers further include an intermediate layer disposed between the first organic compound layer and the second organic compound layer. A specific example of the laminated structure of an organic light-emitting element is a structure in which a substrate, an insulating layer, a first electrode, a first organic compound layer, an intermediate layer, a second organic compound layer, and a second electrode are stacked in this order. The intermediate layer is disposed adjacent to the first organic compound layer and the second organic compound layer. A third organic compound layer may be provided between the second organic compound layer and the second electrode. A protective layer and a color filter may be provided on the second electrode (in the direction opposite to the substrate). If a color filter is provided, a planarization layer may be further provided between the protective layer and the color filter.

[0020] [substrate] Substrates can be made of materials such as quartz, glass, silicon, resin, and metal. Switching elements such as transistors and wiring can be placed on the substrate, and an insulating layer can be further provided on these components. The insulating layer is made of a material that can form contact holes to ensure conductivity between the anode and the wiring, while also ensuring insulation from wiring that is not connected. Examples of materials for forming such an insulating layer include resins such as polyimide; silicon compounds such as silicon oxide and silicon nitride; and so on.

[0021] [electrode] A pair of electrodes consists of a first electrode and a second electrode. Of the first and second electrodes, one is the anode and the other is the cathode. When a voltage is applied in the direction in which the organic light-emitting element emits light, the electrode with the higher potential becomes the anode and the other becomes the cathode. In other words, the electrode that supplies holes to the light-emitting layer is the anode, and the electrode that supplies electrons is the cathode. Each electrode may be made of one type of material, or it may be made of two or more types of materials. Furthermore, each electrode may be a single layer, or it may be a laminate of two or more layers stacked together.

[0022] The anode is preferably formed from a material with a high work function. Examples of such materials include metals such as gold, platinum, silver, copper, nickel, palladium, cobalt, selenium, vanadium, and tungsten; metal oxides such as tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), and indium zinc oxide; mixtures and alloys thereof; and conductive polymers such as polyaniline, polypyrrole, and polythiophene.

[0023] When used as a reflective electrode, the material used to form the anode can be a metal such as chromium, aluminum, silver, titanium, tungsten, and molybdenum; or an alloy or laminate thereof. When used as a transparent electrode, the material used to form the anode can be a metal oxide such as indium tin oxide (ITO) or indium zinc oxide. Photolithography can be used to form the anode.

[0024] The cathode is preferably formed from a material with a low work function. Examples of such materials include alkali metals such as lithium; alkaline earth metals such as calcium; other metals such as aluminum, titanium, manganese, silver, lead, and chromium; oxides, mixtures, and alloys thereof. Examples of alloys include magnesium-silver, aluminum-lithium, aluminum-magnesium, silver-copper, and zinc-silver. Examples of metal oxides include indium tin oxide (ITO). Among these, silver and silver alloys are preferred as the material for forming the cathode, and silver alloys are even more preferred to suppress silver aggregation. The ratio of silver to other metals in the silver alloy is not important as long as silver aggregation can be suppressed. For example, a ratio of silver to other metals of approximately 1:1 (mass ratio) is acceptable. Photolithography can be used to form the cathode.

[0025] The cathode may be formed from a metal oxide such as indium tin oxide (ITO), and the organic light-emitting element may be used as a top-emission element. Alternatively, the reflective electrode may be formed from a metal such as aluminum (Al), and the organic light-emitting element may be used as a bottom-emission element. When forming the cathode, photolithography or sputtering can be used. In particular, it is preferable to form the cathode by sputtering (DC or AC). The cathode (film) formed by sputtering has excellent coverage and can reduce resistance.

[0026] [Protective layer] A protective layer can be provided on the cathode (second electrode). By bonding a glass with a desiccant layer to the cathode to form a protective layer, the intrusion of water and other substances into the organic compound layer can be suppressed, thereby suppressing the occurrence of display defects. Alternatively, by providing a passivation film such as silicon nitride as a protective layer on the cathode, the intrusion of water and other substances into the organic compound layer can be suppressed. The protective layer can be formed by chemical vapor deposition (CVD). Alternatively, after film formation by chemical vapor deposition, a two-layer protective layer may be provided by atomic deposition (ALD). For example, after the cathode is formed, it can be transported to another chamber while maintaining a vacuum, and a silicon nitride film can be formed as a protective layer by CVD. The average thickness of the protective layer is preferably 1 μm or more and 10 μm or less.

[0027] [Color Filter] A color filter can be provided on the protective layer. A color filter corresponding to the size of the organic light-emitting element may be provided on a separate substrate and bonded to the substrate on which the organic light-emitting element is provided, or the color filter may be patterned using photolithography technology. The color filter can be formed from polymer materials or the like.

[0028] [Planarization layer] A planarization layer can be provided between the protective layer and the color filter. Examples of materials that make up the planarization layer include organic compounds. In particular, it is preferable to form the planarization layer with a polymer organic compound such as a resin. The planarization layer may be provided on both the top and bottom (both sides) of the color filter, and the materials that make up the planarization layer may be the same or different. Examples of materials that make up the planarization layer include resins such as polyvinylcarbazole resin, polycarbonate resin, polyester resin, ABS resin, acrylic resin, polyimide resin, phenolic resin, epoxy resin, silicone resin, and urea resin.

[0029] [Opposite substrate] A counter substrate can be provided on the planarized layer. The counter substrate is a substrate provided at a position opposite to the aforementioned substrate. The material used to form the counter substrate can be the same as the material used to form the substrate.

[0030] [Organic compound layer] The organic compound layer includes a first organic compound layer and a second organic compound layer. Either the first organic compound layer or the second organic compound layer includes a light-emitting layer. The first organic compound layer and the second organic compound layer may each be a single layer or a laminate of two or more layers.

[0031] When the organic compound layer is a laminate having multiple layers, the organic compound layer has layers other than the light-emitting layer. Examples of layers other than the light-emitting layer include hole injection layers, hole transport layers, electron blocking layers, hole-exciton blocking layers, electron transport layers, and electron injection layers. Hole transport layers and electron transport layers are also called charge transport layers. The light-emitting layer may be a single layer or a laminate of two or more layers.

[0032] Preferably, the average thickness of each layer constituting the organic compound layer is independently between 1 nm and 10,000 nm (10 μm or less). From the viewpoint of further improving the luminescence characteristics, it is even more preferable that the average thickness of each layer constituting the organic compound layer is independently between 10 nm and 100 nm.

[0033] In this specification, the average thickness of each layer (film) is the average of the thicknesses measured at any three or more points using a stylus step meter. As a stylus step meter, commercially available devices such as the "P-16+" (manufactured by KLA-Tencor) can be used.

[0034] [Emitting layer] Materials that form the light-emitting layer include light-emitting materials, host materials, and light-emitting assist materials. Examples of light-emitting materials include fused ring compounds such as fluorene derivatives, naphthalene derivatives, pyrene derivatives, perylene derivatives, tetracene derivatives, anthracene derivatives, and rubrene, as well as polymer derivatives such as quinacridone derivatives, coumarin derivatives, stilbene derivatives, organoaluminum complexes such as tris(8-quinolinolate)aluminum, iridium complexes, platinum complexes, rhenium complexes, copper complexes, europium complexes, ruthenium complexes, poly(phenylenevinylene) derivatives, poly(fluorene) derivatives, and poly(phenylene) derivatives.

[0035] Examples of host materials and luminescence assist materials include aromatic hydrocarbon compounds, derivatives of aromatic hydrocarbon compounds, carbazole derivatives, dibenzofuran derivatives, dibenzothiophene derivatives, organoaluminum complexes such as tris(8-quinolinolate)aluminum, and organoberylium complexes. The host material preferably has an anthracene skeleton, tetracene skeleton, perylene skeleton, fluorene skeleton, or pyrene skeleton in its molecular structure.

[0036] [Hole injection layer, hole transport layer] As the material for forming the hole injection layer and the hole transport layer, hole injection transport compounds can be used. Examples of hole injection transport compounds include triarylamine derivatives, arylcarbazole derivatives, phenylenediamine derivatives, stilbene derivatives, phthalocyanine derivatives, porphyrin derivatives, poly(vinylcarbazole), poly(thiophene), and other conductive polymers. These hole injection transport materials can also be used as materials for forming the electron blocking layer. The hole injection layer and the hole transport layer may be separate layers or contained within the same layer. Hereinafter, when the hole injection layer and the hole transport layer are contained within the same layer, they will be referred to as the hole injection transport layer.

[0037] [Electron transport layer] As the material for forming the electron transport layer, electron transport materials can be used. Examples of electron transport materials include oxadiazole derivatives, pyrazine derivatives, triazole derivatives, triazine derivatives, quinoline derivatives, quinoxaline derivatives, phenanthroline derivatives, and organoaluminum complexes, as well as fused ring compounds such as fluorene derivatives, naphthalene derivatives, chrysene derivatives, and anthracene derivatives. These electron transport materials can also be used as materials for forming the hole blocking layer.

[0038] [Electron injection layer] As the material for forming the electron injection layer, electron-injectionable materials can be used. These materials are selected considering factors such as the ease of electron injection from the cathode and the balance with hole injection capabilities. Examples of electron-injectionable materials include alkali metal compounds such as lithium fluoride, lithium complexes such as lithium quinolinol, benzimidazolidene derivatives, imidazolidene derivatives, fluvalene derivatives, and acridine derivatives. These organic compounds also include n-type dopants and reducing dopants.

[0039] [Middle class] The intermediate layer is positioned between the first organic compound layer and the second organic compound layer. The intermediate layer contains a metalloxane compound that includes a metal atom with a valency of 3 or higher. Examples of metal atoms with a valency of 3 or higher include tungsten, vanadium, niobium, molybdenum, tantalum, titanium, zirconium, hafnium, silicon, germanium, tin, tellurium, aluminum, gallium, indium, antimony, iron, lanthanum, praseodymium, neodymium, samarium, dysprosium, and ytterbium. In particular, the valency of the metal atom is preferably 5 or higher. The metal atom is preferably tungsten, vanadium, niobium, molybdenum, and tantalum, and more preferably tungsten. It should be noted that the metalloxane compound does not have a crystalline structure like a metal oxide. This is because, while a covalent bond is formed between the metal atom and oxygen atom of the metalloxane compound, an ionic bond is formed between the metal atom and oxygen atom of a metal oxide.

[0040] The average thickness of the intermediate layer is 3 nm to 30 nm. From the viewpoint of further improving the luminous efficiency of the organic light-emitting element and further reducing the driving voltage, it is even more preferable that the average thickness of the intermediate layer be 5 nm to 20 nm. The intermediate layer is preferably formed adjacent to the light-emitting layer.

[0041] (Applications of organic light-emitting diodes) The organic light-emitting element of the present invention can be used, for example, as a component of a display device or lighting device. It can also be used as an exposure light source for an electrophotographic image recording device, a backlight for a liquid crystal display device, or a light-emitting device with a color filter in a white light source.

[0042] <Method for manufacturing organic light-emitting elements> The present invention relates to a method for manufacturing an organic light-emitting element having a laminated structure in which a constituent layer comprising a first electrode, a first organic compound layer, a second organic compound layer, and a second electrode is stacked. The manufacturing method of the present invention comprises the steps of forming a first organic compound layer, applying a predetermined liquid composition onto the first organic compound layer to form an intermediate layer with an average thickness of 3 nm to 30 nm, and forming a second organic compound layer on the intermediate layer. The liquid composition contains a metal alkoxide containing a metal atom with a valency of 3 or higher, and a solvent. Either the first organic compound layer or the second organic compound layer includes a light-emitting layer. The details of the manufacturing method of the present invention will be described below.

[0043] (Process for forming the first organic compound layer) The manufacturing method of the present invention includes a step of forming a first organic compound layer. Methods for forming the first organic compound layer include dry processes and wet processes. Dry processes include vacuum deposition, ionization deposition, sputtering, and plasma methods. A wet process is a method of applying a liquid composition for forming the first organic compound layer, which contains the constituent materials of the organic compound layer and a liquid medium, to a target area such as a substrate. Methods for applying this liquid composition include coating methods such as spin coating, casting, gravure coating, bar coating, roll coating, wire bar coating, dip coating, spray coating, and capillary coating; and printing methods such as screen printing, flexographic printing, offset printing, and inkjet printing. Among these, vacuum deposition, ionization deposition, spray coating, and inkjet printing are preferred, and inkjet printing is more preferred. By employing these methods, organic light-emitting elements with larger areas can be easily manufactured.

[0044] It is preferable to apply a liquid composition for forming the first organic compound to the target area using a wet process, and then dry and remove the liquid medium in the liquid composition to form the first organic compound layer. Drying conditions can be appropriately set depending on the constituent materials of the first organic compound layer and the type of liquid medium. It is preferable to dry the liquid composition in an air atmosphere or in an inert gas atmosphere such as nitrogen or argon. When drying the liquid composition by heating, the heating temperature is preferably 100°C to 250°C, and more preferably 110°C to 200°C. The heating time is preferably 5 minutes to 60 minutes. The pressure during drying of the liquid composition may be atmospheric pressure (1 atmosphere) or reduced pressure (100 Pa to 0.1 MPa).

[0045] (Intermediate layer formation process) The present invention's manufacturing method includes a step of forming an intermediate layer by applying a liquid composition for forming an intermediate layer, which contains a metal alkoxide with a valency of 3 or higher and a solvent, onto a first organic compound layer. From the viewpoint of luminescence efficiency, the intermediate layer is preferably formed adjacent to the light-emitting layer contained in either the first organic compound layer or the second organic compound layer. Methods for applying the liquid composition onto the first organic compound layer include coating methods such as spin coating, casting, gravure coating, bar coating, roll coating, wire bar coating, dip coating, spray coating, and capillary coating; and printing methods such as screen printing, flexographic printing, offset printing, and inkjet printing. Among these, spray coating and inkjet printing are preferred, and inkjet printing is even more preferred. By employing these methods, larger-area organic light-emitting devices can be easily manufactured.

[0046] In the intermediate layer formation process, an intermediate layer with an average thickness of 3 nm to 30 nm is formed. From the viewpoint of further improving luminescence efficiency and manufacturing an organic light-emitting element that can be driven at a lower applied voltage, it is preferable to form an intermediate layer with an average thickness of 5 nm to 20 nm. The average thickness of the intermediate layer to be formed can be controlled, for example, by adjusting the content of the metal alkoxide in the liquid composition or the amount of liquid composition applied.

[0047] The liquid composition for forming the intermediate layer contains a metal alkoxide and a solvent. Preferably, the content (by mass) of the metal alkoxide in the liquid composition is 0.01% by mass or more and 1.00% by mass or less, based on the total mass of the liquid composition.

[0048] Examples of metal alkoxides include tungsten(VI) ethoxide, vanadium(V) oxytriethoxide, niobium(V) ethoxide, niobium(V) isopropoxide, molybdenum(V) ethoxide, tantalum(V) ethoxide, tungsten(V) ethoxide, titanium(IV) ethoxide, titanium(IV) n-propoxide, titanium(IV) isopropoxide, titanium(IV) butoxide, titanium(IV) tert-butoxide, zirconium(IV) ethoxide, zirconium(IV) n-propoxide, hafnium(IV) ethoxide, hafnium(IV) isopropoxide, tetraethoxysilane, tetrapropoxysilane, germanium(IV) ethoxide Examples include toxides, germanium(IV) isopropoxide, tin(IV) isopropoxide, tellurium(IV) ethoxide, aluminum(III) ethoxide, gallium(III) ethoxide, gallium(III) isopropoxide, indium(III) isopropoxide, antimony(III) ethoxide, antimony(III) isopropoxide, iron(III) ethoxide, lanthanum(III) ethoxide, praseodymium(III) isopropoxide, neodymium(III) isopropoxide, samarium(III) isopropoxide, dysprosium(III) isopropoxide, and ytterbium(III) isopropoxide.

[0049] By using a metal alkoxide with a large number of polycondensation reaction sites per molecule, an intermediate layer that is difficult to dissolve in solvents can be formed. For this reason, it is preferable that the valency of the metal atoms contained in the metal alkoxide is 5 or higher. Examples of metal alkoxides containing metal atoms with a valency of 5 or higher include tungsten(VI) ethoxide, vanadium(V) oxytriethoxide, niobium(V) ethoxide, niobium(V) isopropoxide, molybdenum(V) ethoxide, tantalum(V) ethoxide, and tungsten(V) ethoxide.

[0050] The solvent contained in the liquid composition for the intermediate layer is a component used to adjust various properties of the liquid composition, such as viscosity and surface tension. Examples of solvents include water; alcohols such as methanol, ethanol, n-isopropanol, isopropanol, 1-butanol, and 2-butanol; aromatic hydrocarbon compounds such as toluene, o-xylene, p-xylene, mesitylene, chlorobenzene, o-dichlorobenzene, anisole, and phenylcyclohexane; alkyl halides such as dichloromethane and chloroform; ethers such as diethyl ether, dibutyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, and diethylene glycol dimethyl ether; ketones such as dimethoxyethane, cyclopentanone, cyclohexanone, and methyl ethyl ketone; esters such as ethyl acetate, butyl acetate, and methyl benzoate; amide compounds such as dimethylformamide and dimethylacetamide; and cyclic amide compounds (lactams) such as N-methylpyrrolidone and dimethylimidazolidinone. From the viewpoint of further suppressing the elution of the first organic compound layer, the solvent is preferably water and alcohols, and more preferably an alcohol having 3 or fewer carbon atoms. The solvent can be used alone or in combination of two or more.

[0051] It is preferable to apply the liquid composition onto the first organic compound layer and then heat it in a moisture-containing atmosphere such as air. This allows the hydrolysis of the metal alkoxide to proceed more rapidly. It is also preferable to apply the liquid composition onto the first organic compound layer and then heat it to 200°C to 300°C to form an intermediate layer. Heating allows the polycondensation reaction of the metal alkoxide to proceed more sufficiently. The heating time is preferably 5 minutes to 60 minutes. Furthermore, it is preferable to volatilize the solvent contained in the liquid composition for intermediate layer formation by this heating. By volatilizing the solvent, the amount of solvent contained in the intermediate layer can be reduced, and the influence of the solvent in the formed intermediate layer can be suppressed. In addition, in order to facilitate the volatilization of the solvent, it is preferable that the heating temperature be higher than the boiling point of the solvent contained in the liquid composition for intermediate layer formation.

[0052] (Process for forming the second organic compound layer) The manufacturing method of the present invention includes a step of forming a second organic compound layer on an intermediate layer. That is, the method for forming the second organic compound layer is a wet process in which a liquid composition for forming the second organic compound, containing the constituent materials of the organic compound layer and a liquid medium, is applied to the intermediate layer. Methods for applying the liquid composition include coating methods such as spin coating, casting, gravure coating, bar coating, roll coating, wire bar coating, dip coating, spray coating, and capillary coating; and printing methods such as screen printing, flexographic printing, offset printing, and inkjet printing. Among these, spray coating and inkjet printing are preferred, and inkjet printing is even more preferred. By employing these methods, organic light-emitting elements with larger areas can be easily manufactured.

[0053] It is preferable to apply the liquid composition onto the intermediate layer, then dry and remove the liquid medium in the liquid composition to form a second organic compound layer. The drying conditions can be appropriately set depending on the constituent materials of the organic compound layer and the type of liquid medium. Drying is preferably carried out in an air atmosphere or in an inert gas atmosphere such as nitrogen or argon. When drying the liquid composition by heating, the heating temperature is preferably 100°C to 250°C, and more preferably 110°C to 200°C. The heating time is preferably 5 minutes to 60 minutes. The pressure during drying may be normal pressure (1 atmosphere) or reduced pressure (100 Pa to 0.1 MPa).

[0054] <Display device> The display device of the present invention is a device comprising a plurality of pixels, at least one of which comprises the aforementioned organic light-emitting element and a transistor connected to this organic light-emitting element. The details of the display device of the present invention will be described below.

[0055] The display device includes, for example, an image input unit that receives image information from an area CCD, a linear CCD, and a memory card, and an information processing unit that processes the received image information. A CCD is a charge-coupled element. The display device may also be an image information processing device that displays the received image information on a display unit. Furthermore, the display unit of an imaging device or an inkjet recording device may have a touch panel function. Examples of driving methods for the touch panel function include infrared, capacitive, resistive, and electromagnetic induction methods. The display device may also be used in the display unit of a so-called hybrid recording device.

[0056] Next, the details of the display device of the present invention will be described with reference to the drawings. Figure 1A is a schematic cross-sectional view showing an example of a pixel constituting the display device of the present invention. The pixel shown in Figure 1A includes sub-pixels 10R, 10G, and 10B. The sub-pixels 10R, 10G, and 10B are distinguished by their emission color. The emission color may be distinguished and determined by the wavelength of light emitted from the light-emitting layer, or it may be determined by selective transmission or color conversion of the light emitted from the sub-pixels 10R, 10G, and 10B by color filters 7R, 7G, and 7B. Each sub-pixel 10R, 10G, and 10B comprises an interlayer insulating layer 1, a reflective electrode 2 which is a first electrode provided on the interlayer insulating layer 1, an insulating layer 3 covering the end of the reflective electrode 2, and an organic semiconductor layer 4 covering the first electrode and the insulating layer. Each sub-pixel 10R, 10G, and 10B further comprises a transparent electrode 5, a protective layer 6, and color filters 7R, 7G, and 7B, respectively.

[0057] Transistors and capacitive elements may be arranged in the layer below or inside the interlayer insulating layer 1. The transistors and the first electrode may be electrically connected via contact holes (not shown). The insulating layer 3 is also called a bank or pixel isolation layer. The insulating layer 3 covers the end of the first electrode (reflecting electrode 2) and is arranged to surround the first electrode. The portion of the first electrode not covered by the insulating layer 3 is connected to the organic semiconductor layer 4 and becomes a light-emitting region. The organic semiconductor layer (organic compound layer) 4 has a hole injection layer 41, a hole transport layer 42, an intermediate layer 43, a light-emitting layer 44, and an electron transport layer 45. The second electrode may be a transparent electrode, a reflective electrode, or a semi-transparent electrode. The protective layer 6 is a layer for reducing the penetration of liquid components such as water into the organic compound layer. The protective layer may consist of multiple layers. If the protective layer consists of multiple layers, the multiple layers may include inorganic compound layers and organic compound layers.

[0058] Color filters 7R, 7G, and 7B are distinguished according to color. The color filters may be formed on a planarization film (not shown). Alternatively, a resin protective layer (not shown) may be placed on the color filters. Furthermore, the color filters may be formed on the protective layer 6, or they may be bonded to an opposing substrate such as a glass substrate after being provided on it.

[0059] Figure 1B is a schematic cross-sectional view showing one embodiment of the display device of the present invention. The display device 100 shown in Figure 1B comprises an organic light-emitting element 26 and an active element 18 such as a thin-film transistor (TFT) connected to the organic light-emitting element 26. A transistor such as a TFT is an example of an active element. The display device 100 comprises a substrate 11 formed of a material such as glass or silicon, and an insulating layer 12 provided on the substrate 11. The active element 18 such as a TFT is arranged on the insulating layer 12. The active element 18 comprises a gate electrode 13, a gate insulating film 14, a semiconductor layer 15, a drain electrode 16, and a source electrode 17. An insulating film 19 is provided on the upper part of the active element 18. The anode 21 and the source electrode 17 constituting the organic light-emitting element 26 are connected via a contact hole 20 provided in the insulating film 19. Note that the method of electrical connection between the electrodes (anode, cathode) included in the organic light-emitting element and the electrodes (source electrode, drain electrode) included in the active element is not limited to the embodiment shown in Figure 1B. In other words, it is sufficient that the anode or cathode is electrically connected to the TFT source electrode or drain electrode.

[0060] In the display device 100 shown in Figure 1B, a single-layer organic semiconductor layer 22 is shown, but the organic semiconductor layer may include multiple layers. A first protective layer 24 and a second protective layer 25 are provided on the cathode 23 to reduce the degradation of the organic light-emitting element 26. As the active element 18 constituting the display device 100, for example, a transistor using a single-crystal silicon wafer or a thin-film transistor having an active layer on an insulating surface of a substrate can be used. Examples of the active layer include non-single-crystal silicon such as single-crystal silicon, amorphous silicon, and microcrystalline silicon, and non-single-crystal oxide semiconductors such as indium zinc oxide and indium gallium zinc oxide.

[0061] Active elements such as transistors that constitute a display device may be formed within a substrate such as a silicon substrate. "Formed within a substrate" means that the transistors are formed by processing the substrate, such as a silicon substrate. In other words, the substrate and the transistors may be formed integrally.

[0062] The luminescence of an organic light-emitting element is controlled by a TFT, which is an example of an active element (switching element). By arranging multiple organic light-emitting elements in a plane, an image can be displayed by controlling the luminescence of each of the multiple organic light-emitting elements. The switching element may be a transistor formed from low-temperature polysilicon, or an active matrix driver formed on a substrate such as a silicon substrate, in addition to a TFT. If the size of the display area is, for example, about 0.5 inches, it is preferable to arrange the organic light-emitting elements on a silicon substrate.

[0063] Figure 2 is a schematic diagram showing another embodiment of the display device of the present invention. The display device 1000 shown in Figure 2 comprises an upper cover 1001 and a lower cover 1009 arranged opposite each other. Furthermore, the display device 1000 comprises a touch panel 1003, a display panel 1005, a frame 1006, a circuit board 1007, and a battery 1008, which are arranged between the upper cover 1001 and the lower cover 1009. Flexible printed circuits (FPCs) 1002 and 1004 are connected to the touch panel 1003 and the display panel 1005, respectively. Transistors are printed on the circuit board 1007. When the display device is a portable device, a battery 1008 is usually provided. Note that the battery 1008 may be provided in a different location.

[0064] The display device may have red (R), green (G), and blue (B) color filters. The red, green, and blue color filters may be arranged in a delta array, a stripe array, or a mosaic array. The display device can be used in the display unit of a mobile terminal. When the display device is used in the display unit of a mobile terminal, the display device may have both display and operation functions. Examples of mobile terminals include smartphones and other mobile phones, tablets, and head-mounted displays.

[0065] The display device can be used in the display unit of an imaging device that comprises an optical unit having multiple lenses and an image sensor that receives light passing through the optical unit. The imaging device may have a display unit that displays information acquired by the image sensor. The display unit may be located outside the imaging device or housed within a viewfinder. Examples of imaging devices include digital cameras and digital video cameras. The imaging device can also be called a photoelectric converter.

[0066] Figure 3A is a schematic diagram showing an example of an imaging device. The imaging device 1100 shown in Figure 3A comprises a viewfinder 1101, a rear display 1102, an operating unit 1103, and a housing 1104. A display device can be used as the viewfinder 1101. The display device may display not only the image to be captured, but also environmental information and imaging instructions. Environmental information may include the intensity of ambient light, the direction of ambient light, the speed at which the subject is moving, and the possibility of the subject being obscured by an obstruction.

[0067] Since the optimal timing for imaging is only a short time, it is preferable to be able to display information quickly. Organic light-emitting elements have a fast response speed, making them suitable for use in display devices. The imaging device 1100 has an optical section (not shown). The optical section has multiple lenses that form an image on the image sensor housed in the housing 1104. The focus of the multiple lenses can be adjusted by controlling their relative positions. The relative positions of the multiple lenses can also be controlled automatically.

[0068] Figure 3B is a schematic diagram showing an example of a portable device. The portable device 1200 shown in Figure 3B comprises a display unit 1201, an operation unit 1202, and a housing 1203. An organic light-emitting element can be used for the display unit 1201. The housing 1203 comprises a circuit, a printed circuit board having the circuit, a battery, and a communication unit. The operation unit 1202 may be a button or a touch panel type response unit. The operation unit 1202 may also be a biometric recognition unit that recognizes fingerprints to unlock the device. A portable device further comprising a communication unit can also be called a communication device. The portable device 1200 may further be equipped with a lens and an image sensor to have a camera function. Images captured by the camera function are displayed on the display unit 1201. Examples of portable devices 1200 include smartphones and laptop computers.

[0069] Figure 4A is a schematic diagram showing another embodiment of the display device of the present invention. The display device 1300 shown in Figure 4A is a monitor such as a television or personal computer. The display device 1300 comprises a frame 1301, a display unit 1302, and a base 1303 that supports the display unit 1302. An organic light-emitting element can be used for the display unit 1302. The form of the base 1303 is not limited to the form shown in Figure 4A, and the lower edge of the frame 1301 may also serve as the base. Furthermore, the frame 1301 and the display unit 1302 may be curved. If the frame 1301 and the display unit 1302 are curved, their radii of curvature are preferably 5,000 mm or more and 6,000 mm or less.

[0070] Figure 4B is a schematic diagram showing another embodiment of the display device of the present invention. The display device 1310 shown in Figure 4B is a so-called foldable display device that is configured to be bendable. The display device 1310 comprises a first display unit 1311, a second display unit 1312, a housing 1313, and a bending point 1314. Organic light-emitting elements can be used in the first display unit 1311 and the second display unit 1312. The first display unit 1311 and the second display unit 1312 may be a single display unit without a seam. The first display unit 1311 and the second display unit 1312 can be separated at the bending point 1314. The first display unit 1311 and the second display unit 1312 may each display different images, or they may display a single image.

[0071] Figure 5A is a schematic diagram showing an example of a lighting device. The lighting device 1400 shown in Figure 5A comprises a housing 1401, a light source 1402, a circuit board 1403, an optical film 1404, and a light diffusion unit 1405. An organic light-emitting element can be used as the light source 1402. The optical film 1404 may be a filter that improves the color rendering of the light source. The light diffusion unit 1405 can effectively diffuse the light from the light source, such as for lighting up, and deliver light over a wide area. The optical film and the light diffusion unit may be provided on the light-emitting side of the lighting device. A cover may be provided on the outermost part as needed.

[0072] A lighting device is, for example, a device for illuminating a room, and comprises a light source and a component that transmits the light emitted by the light source. The lighting device may emit light in any color from blue to red, not just white or daylight white. "White" refers to a color with a color temperature of about 4,200K, and "daylight white" refers to a color with a color temperature of about 5,000K. The lighting device may further include a dimming circuit to adjust the light. The lighting device may further include a power supply circuit connected to an organic light-emitting element used as the light source. The power supply circuit is a circuit that converts AC voltage to DC voltage. The lighting device may further include a light diffuser or a color filter as a component that transmits the light emitted by the light source. The lighting device may also further include a heat dissipation section that releases heat from inside the device to the outside. Examples of materials that make up the heat dissipation section include metals with high specific heat and liquid silicon.

[0073] Figure 5B is a schematic diagram showing an example of a mobile body. The mobile body shown in Figure 5B is an automobile 1500 equipped with lighting devices such as taillights 1501 that illuminate when the brakes are applied. Organic light-emitting elements can be used in the taillights 1501. The taillights 1501 may be equipped with a protective member to protect the organic light-emitting elements. The protective member can be made of a transparent material with a certain degree of strength. Examples of such materials include resin materials such as polycarbonate. Resin materials such as polycarbonate may contain franciocarboxylic acid derivatives or acrylonitrile derivatives.

[0074] The automobile 1500 may further include a body 1503 and windows 1502 provided in the body 1503. The windows 1502 may be transparent displays using organic light-emitting elements, unless they are for checking the front and rear of the automobile 1500. Components such as electrodes that constitute the transparent display using organic light-emitting elements are made of transparent materials.

[0075] Examples of mobile bodies other than the automobile 1500 shown in Figure 5B include ships, aircraft, and drones. The mobile body may be equipped with a body and a light fixture mounted on the body that emits light to indicate the body's position. Organic light-emitting elements can be used for the light fixture.

[0076] The display device can be applied to imaging display devices such as smart glasses, head-mounted displays, and smart contact lenses, which are wearable devices. Such an imaging display device comprises, for example, a photoelectrically convertible imaging device that converts visible light into electrical signals, and a display device that emits visible light.

[0077] Figure 6A is a schematic diagram showing an example of a wearable device. An imaging device 1602, such as a CMOS sensor or SPAD sensor, is provided on the front surface of the lens 1601 of the smart glasses 1600 (eyeglasses) shown in Figure 6A. A CMOS (Complementary Metal-Oxide-Semiconductor) sensor is a solid-state image sensor using a complementary metal-oxide-semiconductor. A SPAD (Single Photon Avalanche Diode) sensor is an electronic element that outputs a single large electrical pulse signal when a single photon enters the pixel, through avalanche-like multiplication. A display device is provided on the back surface of the lens 1601. The smart glasses 1600 further includes a control device 1603. The control device 1603 functions as a power supply, providing power to the imaging device 1602 and the display device, and also controls the operation of the imaging device 1602 and the display device. An optical system for focusing light onto the imaging device 1602 is formed in the lens 1601.

[0078] Figure 6B is a schematic diagram showing another example of a wearable device. The smart glasses 1610 (eyeglasses) shown in Figure 6B include a control device 1612. The control device 1612 is equipped with an imaging device corresponding to the imaging device 1602 (Figure 6A) and a display device. The lens 1611 has an optical system formed therein for projecting light emitted from the imaging device and display device within the control device 1612, and an image is projected. The control device 1612 functions as a power supply to supply power to the imaging device and display device, and also controls the operation of the imaging device and display device. The control device may have a gaze detection unit that detects the wearer's gaze. Infrared light can be used for gaze detection. The infrared light emitter emits infrared light towards the eyeball of the user who is gazing at the displayed image. The imaging unit, which has a photodetector, detects the reflected light from the eyeball of the emitted infrared light, thereby obtaining an image of the eyeball. By having a reduction means that reduces the light from the infrared light emitter to the display unit in a planar view, the deterioration of image quality can be reduced.

[0079] The smart glasses 1610 detect the user's gaze toward the displayed image from an image of the eyeball obtained by imaging with infrared light. Any known method can be applied to gaze detection using the image of the eyeball. As an example, a gaze detection method based on the Purkinje image obtained by the reflection of the irradiated light from the cornea can be used. Specifically, gaze detection processing based on the pupil-corneal reflection method is performed. Using the pupil-corneal reflection method, the user's gaze is detected by calculating a gaze vector representing the orientation (rotation angle) of the eyeball based on the pupil image and the Purkinje image included in the image of the eyeball.

[0080] The display device may have an imaging device with a light-receiving element, and may control the display image of the display device based on the user's gaze information from the imaging device. Specifically, based on the gaze information, a first field of view area that the user is fixated on and a second field of view area other than the first field of view area are determined. The first and second field of view areas may be determined by the control device of the display device, or they may be determined by an external control device and received. In the display area of ​​the display device, the display resolution of the first field of view area may be controlled to be higher than the display resolution of the second field of view area. That is, the resolution of the second field of view area may be lower than that of the first field of view area.

[0081] Furthermore, the display area has a first display area and a second display area different from the first display area, and based on line-of-sight information, the area with higher priority is determined from the first display area and the second display area. The first and second line-of-sight areas may be determined by the control device of the display device, or they may be determined by an external control device and received. The resolution of the high-priority area may be controlled to be higher than the resolution of the areas other than the high-priority area. In other words, the resolution of areas with relatively lower priority may be lower.

[0082] Artificial intelligence (AI) may be used to determine the first field of view area and high-priority areas. The AI ​​may be a model configured to estimate the angle of gaze and the distance to the target object at the end of the gaze from the image of the eye, using the image of the eye and the direction the eye was actually looking in the image as training data. The AI ​​program may be installed in a display device, an imaging device, or an external device. If the AI ​​program is installed in an external device, information is transmitted to the display device via communication. When display control is performed based on gaze detection, it is preferably applied to smart glasses that further have an imaging device for capturing images of the outside. The smart glasses can display the captured external information in real time.

[0083] As described above, by using a display device equipped with the organic light-emitting element of the present invention, it becomes possible to display information stably for a long period of time with good image quality. Furthermore, the highly efficient and high-brightness light output enables both good visibility outdoors and power-saving display. [Examples]

[0084] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited in any way by the following examples unless it exceeds the gist of the invention. Unless otherwise specified, amounts of components indicated in "parts" and "%" are based on mass.

[0085] <Method for measuring layer thickness (average thickness)> Using a stylus step meter (product name "P-16+", manufactured by KLA-Tencor), the thickness of any three points in the film was measured, and the average value was calculated to determine the thickness (average thickness) of each formed layer.

[0086] <Manufacturing of Organic Light-Emitting Diodes> (Example 1) A transparent conductive support substrate (ITO substrate) was obtained by depositing an ITO film on a glass substrate using the sputtering method to form a 100 nm thick anode. A solution of poly-TPD (Poly[N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)-benzidine)) dissolved in toluene was prepared. The prepared solution was spin-coated onto a UV-ozone treated ITO substrate, and then dried at 200°C for 30 minutes to form a hole injection transport layer with an average thickness of 30 nm.

[0087] A liquid composition for forming an intermediate layer was prepared by dissolving tungsten(VI) ethoxide in ethanol, with a tungsten(VI) ethoxide concentration of 0.05%. After spin-coating the liquid composition onto a hole injection transport layer, it was dried at 200°C for 30 minutes to form an intermediate layer with an average thickness of 5 nm.

[0088] 26DCzPPy(2,6-Bis(3-(9H-carbazol-9-yl)phenyl)pyridine) and Ir(mppy)3(Tris[2-(p-tolyl)pyridine]iridium(III)) were prepared. A solution was prepared by mixing these in a mass ratio of 97:3 and dissolving it in toluene. After spin-coating the solution onto an intermediate layer, it was dried at 110°C for 15 minutes to form an emissive layer with an average thickness of 35 nm, obtaining a film sample. The obtained film sample was placed in a vacuum deposition machine, and an electron transport layer (TPBi) with an average thickness of 55 nm, an electron injection layer (LiF) with an average thickness of 0.5 nm, and a cathode (aluminum) with an average thickness of 100 nm were continuously formed by deposition. Next, in a dry air atmosphere, a protective glass plate was placed over it and then sealed with an acrylic resin adhesive to obtain an organic light-emitting element.

[0089] (Comparative Example 1) An organic light-emitting element was manufactured in the same manner as in Example 1 described above, except that an intermediate layer was not formed on the hole injection transport layer.

[0090] (Comparative Example 2) PEDOT:PSS (a composite of poly(3,4-ethylenedioxythiophene) and polystyrene sulfonic acid, trade name "Clevios P ​​AI 4083", manufactured by Heraeus) was prepared. This PEDOT:PSS was dispersed in water to prepare a liquid composition for forming an intermediate layer with a PEDOT:PSS concentration of 1.00%. An organic light-emitting element was manufactured in the same manner as in Example 1 described above, except that the liquid composition prepared in this way was used.

[0091] (Examples 2-10, Comparative Examples 3-6) An organic light-emitting element was manufactured in the same manner as in Example 1 described above, except that the intermediate layer was formed under the conditions shown in Table 1. The average thickness of the formed intermediate layer is shown in Table 1.

[0092] <Rating> The manufactured organic light-emitting devices were evaluated as follows. In this invention, "A" and "B" were considered acceptable levels, and "C" was considered unacceptable levels in the evaluation criteria for each item shown below. The evaluation results are shown in Table 1.

[0093] (External quantum efficiency, driving voltage) Using a spectroradiometer (product name "SR-LEDW-5N", manufactured by Topcon Techno House) and a DC voltage / current source (product name "6253", manufactured by ADC), a current density of 10 mA / cm² was measured. 2 The external quantum efficiency and drive voltage of organic light-emitting devices manufactured under the specified conditions were measured. The external quantum efficiency and drive voltage were then evaluated according to the evaluation criteria shown below. [External quantum efficiency] A: The external quantum efficiency was 1.3 times or more that of Comparative Example 1. B: The external quantum efficiency was 1.1 times or more but less than 1.3 times that of Comparative Example 1. C: The external quantum efficiency was less than 1.1 times that of Comparative Example 1. [Drive voltage] A: The drive voltage was less than 1.1 times that of Comparative Example 1. B: The drive voltage was 1.1 times or more but less than 1.3 times that of Comparative Example 1. C: The drive voltage was 1.3 times or more than that of Comparative Example 1.

[0094] (Stability of liquid compositions) The liquid composition for forming the intermediate layer was left to stand at room temperature (25°C) for one month. The state of the liquid composition after standing was observed visually, and its stability was evaluated according to the evaluation criteria shown below. A: No sedimentation of solid matter was observed. C: Sedimentation of solid matter was observed.

[0095] TIFF2026047164000002.tif109170 [Explanation of symbols]

[0096] Single-layer insulating layer 2 reflective electrode 3. Insulating layer 4 Organic semiconductor layer 5 Transparent electrode 6 Protective layer 7R, 7G, 7B color filters 10R, 10G, 10B sub-pixels 11 circuit boards 18 Active elements 21 Anode 22 Organic semiconductor layer 23 Cathode 26 Organic light-emitting diodes

Claims

1. A method for manufacturing an organic light-emitting element having a stacked structure in which a first electrode, a first organic compound layer, an intermediate layer, a second organic compound layer, and a second electrode are stacked in this order, The process of forming the first organic compound layer, A step of applying a liquid composition onto the first organic compound layer to form the intermediate layer with an average thickness of 3 nm or more and 30 nm or less, The process includes forming the second organic compound layer on the intermediate layer, Either the first organic compound layer or the second organic compound layer includes a light-emitting layer, A method for producing an organic light-emitting element, characterized in that the liquid composition contains a metal alkoxide containing a metal atom with a valency of 3 or higher, and a solvent.

2. The method for manufacturing an organic light-emitting element according to claim 1, wherein the valence of the metal atom is 5 or more.

3. A method for manufacturing an organic light-emitting element according to claim 1, which involves forming the intermediate layer with an average thickness of 5 nm or more and 20 nm or less.

4. The method for producing an organic light-emitting element according to claim 1, wherein the liquid composition is applied to the first organic compound layer, and then heated to 200°C or higher to form the intermediate layer.

5. A method for manufacturing an organic light-emitting element according to any one of claims 1 to 4, wherein the intermediate layer is formed adjacent to the light-emitting layer.

6. A method for manufacturing an organic light-emitting element according to any one of claims 1 to 4, wherein the metal atom is tungsten.

7. The method for producing an organic light-emitting element according to any one of claims 1 to 4, wherein the solvent is an alcohol having 3 or fewer carbon atoms.

8. An organic light-emitting element having a stacked structure in which a first electrode, a first organic compound layer, an intermediate layer, a second organic compound layer, and a second electrode are stacked in this order, The aforementioned intermediate layer is a layer with an average thickness of 3 nm or more and 30 nm or less, which is placed between the first organic compound layer and the second organic compound layer. Either the first organic compound layer or the second organic compound layer includes a light-emitting layer, The organic light-emitting element is characterized in that the intermediate layer contains a metalloxane compound containing a metal atom with a valency of 3 or higher.

9. A display device having multiple pixels, A display device characterized in that at least one of the plurality of pixels comprises an organic light-emitting element according to claim 8 and a transistor connected to the organic light-emitting element.

Images