Method for manufacturing organic light-emitting elements

Abstract

The present invention provides a method for manufacturing an organic light-emitting element that can improve luminous efficiency and element lifetime when forming an organic compound layer on a non-ductile substrate by a coating method. [Solution] A method for manufacturing an organic light-emitting element, comprising a pair of electrodes and an organic compound layer disposed between the electrodes on a substrate, comprising: a liquid application step of applying a liquid composition containing a liquid component and an organic compound constituting the organic compound layer onto electrodes formed on the substrate; a film formation step of evaporating the liquid component contained in the liquid composition applied to the electrodes by the liquid application step to form an organic compound film containing an organic compound; and a pressurization step of bringing a pressurizing means into contact with the organic compound film after the film formation step, heating and pressurizing the organic compound film to form an organic compound layer, wherein the ratio of the density of the organic compound layer produced by the pressurization step (A) to the density of the organic compound layer produced without the pressurization step (B) satisfies 1.001 ≤ A / B ≤ 1.200.

Description

Technical Field

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

Background Art

[0002] An organic light-emitting device (Organic Light Emitting Device: OLED) is an electronic device having a pair of electrodes, a first electrode and a second electrode, and an organic compound layer disposed between the pair of electrodes. By injecting electrons and holes from the pair of electrodes into the organic compound layer, respectively, an organic compound having a light-emitting property in the organic compound layer is activated from the ground state to the excited state, and excess energy is released as light when returning from the excited state to the ground state. An organic light-emitting device is also called an organic electroluminescence device or an organic EL device. As a method for forming the organic compound layer in an organic light-emitting device, a vapor deposition method in which a material constituting the organic compound layer is vapor-deposited on a substrate under high vacuum is widely used. However, the vapor deposition method has problems in material utilization rate and manufacturing cost, and various countermeasures have been taken. As one of these countermeasures, a coating method in which a liquid composition in which a material constituting the organic compound layer is dissolved, dispersed, or melted in a solvent is uniformly applied onto a substrate to form the organic compound layer has been studied.

[0003] However, generally, it is known that an organic light-emitting device manufactured using the coating method is less likely to obtain sufficient device performance compared to an organic light-emitting device manufactured by the vapor deposition method. In contrast, Patent Document 1 discloses a configuration in which a coating solution of a hole transport layer is applied to a substrate, heated, dried under reduced pressure, and then pressurized to atmospheric pressure to produce a hole transport layer, thereby improving the hole transport efficiency and the light emission efficiency. Further, Patent Document 2 discloses a configuration in which a coating solution of an organic light-emitting layer is applied to a conductive film, and the periphery of the sample is gripped with a clip and dried while applying tension to improve the light emission efficiency of the organic light-emitting device. Further, Patent Document 3 discloses a configuration in which a coating solution of a light-emitting layer is applied onto a transparent support substrate composed of a PET film and an ITO transparent electrode, and dried while applying tension to the substrate with a tenter to improve the light emission efficiency of the light-emitting layer. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2013-235714 [Patent Document 2] Japanese Patent Publication No. 2011-171092 [Patent Document 3] International Publication No. 2011 / 114870 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] However, Patent Document 1 does not mention the deterioration of film properties caused by the formation of the organic light-emitting layer by the coating method itself. Furthermore, the configurations described in Patent Documents 2 and 3 cannot be applied to substrates that do not have ductility.

[0006] The present invention has been made in view of the above problems, and aims to provide a method for manufacturing an organic light-emitting element that can improve luminous efficiency and element lifetime when forming an organic compound layer on a non-ductile substrate by a coating method. [Means for solving the problem]

[0007] The above objective is achieved by the present invention as described below. Specifically, the present invention provides a method for manufacturing an organic light-emitting element, comprising a pair of electrodes and an organic compound layer disposed between the electrodes on a substrate, comprising: a liquid application step of applying a liquid composition containing a liquid component and an organic compound constituting the organic compound layer to electrodes formed on the substrate; a film formation step of evaporating the liquid component contained in the liquid composition applied to the electrodes by the liquid application step to form an organic compound film containing an organic compound; and a pressurizing step of bringing a pressurizing means into contact with the organic compound film after the film formation step, heating and pressurizing the organic compound film to form an organic compound layer, wherein the ratio of the density of the organic compound layer produced through the pressurizing step (A) to the density of the organic compound layer produced without the pressurizing step (B) satisfies 1.001 ≤ A / B ≤ 1.200. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a method for manufacturing an organic light-emitting element that can improve luminous efficiency and element lifetime when forming an organic compound layer on a non-ductile substrate by a coating method. [Brief explanation of the drawing]

[0009] [Figure 1] (a) A schematic cross-sectional view showing an example of a pixel of a display device according to one embodiment of the present invention. (b) A schematic cross-sectional view showing an example of a display device using an organic light-emitting element according to one embodiment of the present invention. [Figure 2] This is a schematic diagram of an example of a display device using an organic light-emitting element according to one embodiment of the present invention. [Figure 3] (a) A schematic diagram showing an example of an imaging device according to one embodiment of the present invention. (b) A schematic diagram showing an example of a portable device according to one embodiment of the present invention. [Figure 4] (a) A schematic diagram showing an example of a display device according to one embodiment of the present invention. (b) A schematic diagram showing an example of a foldable display device. [Figure 5](a) A schematic diagram showing an example of a lighting device according to one embodiment of the present invention. (b) A schematic diagram showing an automobile, which is an example of a mobile body according to one embodiment of the present invention. [Figure 6] (a) A schematic diagram showing an example of a wearable device according to one embodiment of the present invention. (b) A schematic diagram showing an example of a wearable device according to one embodiment of the present invention, which includes an imaging device. [Modes for carrying out the invention]

[0010] The present invention will be further described in detail below with reference to preferred embodiments. It will be readily apparent to those skilled in the art that the present invention is not limited to the following description, and that its form and details can be modified in various ways without departing from the spirit and scope of the invention. That is, the present invention should not be construed as being limited by the following description. Unless otherwise specified, the physical properties are values ​​at room temperature (25°C).

[0011] The inventors manufactured an organic light-emitting device by forming an organic compound layer (organic light-emitting layer) containing a luminescent organic compound on an electrode formed on a substrate using a coating method, and investigated its performance. Specifically, a liquid composition containing an organic compound constituting the organic compound layer and a liquid component was applied to the electrode, and the liquid component was evaporated to form an organic compound film. Subsequently, a pressurizing means was brought into contact with the organic compound film, and the organic compound film was heated and pressurized to form an organic compound layer. At this time, the inventors found that by adjusting the ratio of the density of the organic compound layer after pressurization (A) to the density of the organic compound layer before pressurization (B) to satisfy the following formula (1), the luminous efficiency of the organic light-emitting device and its luminous efficiency were improved, leading to the present invention. 1.001 ≤ A / B ≤ 1.200 (1)

[0012] In the pressurization process, the organic compound film is heated and softened, and then pressurized by a pressurizing means, which crushes the pores contained in the organic compound film. The inventors speculate that this improves the density of the organic compound layer formed through the pressurization process, thereby improving the luminous efficiency and device lifespan of the organic light-emitting element.

[0013] <Organic light-emitting device> The organic light-emitting device has a substrate, a pair of electrodes, and an organic compound layer disposed between the electrodes. Each component of the organic light-emitting device will be described below.

[0014] (Substrate) As the substrate, those formed of quartz, glass, silicon, resin, metal, etc. can be used. Also, switching elements such as transistors, wirings, etc. may be provided on the substrate, and an insulating layer may be provided thereon. As the insulating layer, in order to ensure conduction between the anode and the wiring, any material can be used as long as it can form contact holes and has insulation from the wiring that should not be connected. Specifically, examples of the insulating layer include those formed of resins such as polyimide, and silicon compounds such as silicon oxide and silicon nitride. Also, the substrate may not have extensibility.

[0015] (Electrodes) A pair of electrodes is provided in the organic light-emitting device. The pair of electrodes are the anode and the cathode. When a voltage is applied in the direction in which the organic light-emitting device emits light, the electrode with a higher potential becomes the anode and the other becomes the cathode. Also, it can be said that the electrode that supplies holes to the light-emitting layer is the anode and the electrode that supplies electrons is the cathode.

[0016] As the constituent material of the anode, those with a large work function are preferred. For example, metals such as gold, platinum, silver, copper, nickel, palladium, cobalt, selenium, vanadium, and tungsten. Also, metal oxides such as tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), indium zinc oxide. Furthermore, mixtures or alloys thereof, and conductive polymers such as polyaniline, polypyrrole, and polythiophene can be mentioned. One or more kinds of electrode constituent materials may be used. Also, the anode may be composed of one layer or two or more layers.

[0017] For use as a reflective electrode, the anode can be made from materials such as metals like chromium, aluminum, silver, titanium, tungsten, and molybdenum; alloys or laminates of these metals can also be used. For use as a transparent electrode, oxides such as indium tin oxide (ITO) and indium zinc oxide can be used as the anode material. Photolithography can be used to form the anode.

[0018] On the other hand, materials with a small work function are preferred for the cathode. Examples include alkali metals such as lithium; alkaline earth metals such as calcium; other metals such as aluminum, titanium, manganese, silver, lead, and chromium; and oxides, mixtures, and alloys thereof. Examples of alloys include magnesium-silver, aluminum-lithium, aluminum-magnesium, silver-copper, and zinc-silver. Metal oxides such as indium tin oxide (ITO) may also be used. One or more types of materials may be used for the electrode components. The cathode may also be composed of one or more layers. Among these, the use of silver is preferred, and a silver alloy is even more preferred in order to suppress silver aggregation. The ratio of alloys is not a concern as long as silver aggregation is suppressed. For example, a ratio of about 1:1 may be used.

[0019] The cathode may be a top-emission element using an oxide conductive layer such as indium tin oxide (ITO), or a bottom-emission element using a reflective electrode such as aluminum (Al). Photolithography can also be used to form the cathode. Among these methods, sputtering (DC or AC) is preferred for forming the cathode. This is because the film formed by sputtering has excellent coverage and makes it easy to reduce resistance.

[0020] (protective layer) The protective layer can be provided on the cathode. For example, by bonding a glass with a desiccant layer onto the cathode, the intrusion of water and other substances into the organic compound layer can be suppressed, thereby preventing display defects. Alternatively, a passivation film such as silicon nitride may be provided on the cathode to suppress the intrusion of water and other substances into the organic compound layer. 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 forming the cathode, 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 thickness of the protective layer is preferably 1 μm to 10 μm.

[0021] (Color filter) The color filter can be placed on top of the protective layer. For example, a color filter corresponding to the size of the organic light-emitting element may be placed on a separate substrate and bonded to the substrate on which the organic light-emitting element is placed, or the color filter may be patterned using photolithography technology. The color filter can be made of polymer material or the like.

[0022] (flattening layer) A planarization layer can be provided between the color filter and the protective layer. Examples of constituent materials for the planarization layer include organic compounds, with high-molecular-weight organic compounds being particularly preferred. The planarization layer may be provided on both sides of the color filter; in this case, the constituent materials of each planarization layer may be the same or different. Examples of constituent materials for the planarization layer include polyvinylcarbazole resin, polycarbonate resin, polyester resin, ABS resin, acrylic resin, polyimide resin, phenolic resin, epoxy resin, silicone resin, and urea resin. Here, ABS resin is a resin composed of three monomers: acrylonitrile, butadiene, and styrene.

[0023] (Opposite substrate) The opposing substrate can be placed on top of the planarization layer. Because the opposing substrate is placed opposite the substrate, it is called an opposing substrate. The constituent materials of the opposing substrate are the same as those listed for the constituent materials of the substrate.

[0024] (organic compound layer) The organic compound layer constituting the organic light-emitting element comprises at least a pair of electrodes, a first electrode and a second electrode, and an organic compound layer that is a light-emitting layer positioned between the first electrode and the second electrode. The organic compound layer may be a single layer or a laminate having multiple layers, as long as it has a light-emitting layer.

[0025] The luminescent layer may be formed by including a luminescent organic compound, but may not contain any other components. In other words, the luminescent layer may be a layer formed solely by a luminescent organic compound. Furthermore, the luminescent layer may also contain an organic compound (I) different from the luminescent organic compound, in addition to the luminescent organic compound. When the luminescent organic compound is a phosphorescent material, it is preferable that the lowest excited triplet energy of organic compound (I) is equal to or greater than the lowest excited triplet energy of the luminescent organic compound. Furthermore, when the luminescent organic compound is a fluorescent material, it is preferable that the lowest excited singlet energy of organic compound (I) is equal to or greater than the lowest excited singlet energy of the luminescent organic compound.

[0026] Furthermore, the light-emitting layer may also contain an organic compound (II) different from the luminescent organic compound and the organic compound (I). When the luminescent organic compound is a phosphorescent material, it is preferable that the lowest excited triplet energy of organic compound (II) is equal to or greater than the lowest excited triplet energy of the luminescent organic compound and less than or equal to the lowest excited triplet energy of organic compound (I). Furthermore, when the luminescent organic compound is a fluorescent material, it is preferable that the lowest excited singlet energy of organic compound (II) is equal to or greater than the lowest excited singlet energy of the luminescent organic compound and less than or equal to the lowest excited singlet energy of organic compound (I).

[0027] When the light-emitting layer contains a light-emitting organic compound and organic compound (I), the light-emitting organic compound is the dopant of the light-emitting layer, and organic compound (I) is the host of the light-emitting layer. Furthermore, when organic compound (II) is also included, organic compound (II) is the assisting material.

[0028] The host is the component that makes up the largest amount by mass among the constituent materials of the light-emitting layer. The dopant is a component that makes up the constituent materials of the light-emitting layer but has a smaller amount by mass than the host, and is responsible for the primary light emission. The assist material is a component that makes up the constituent materials of the light-emitting layer but has a smaller amount by mass than the host, and assists the light emission of the dopant. The assist material is also called the second host.

[0029] When a luminescent organic compound is used as a guest in the luminescent layer, the guest content (mass%) is preferably 0.01% to 20.0% by mass, and more preferably 0.1% to 10.0% by mass, based on the total mass of the luminescent layer. The total content of the components constituting the luminescent layer is equal to the total mass of the luminescent layer.

[0030] If the organic compound layer is a laminate having multiple layers, at least one of the organic compound layers is an emissive layer. In addition to the emissive layer, the organic compound layer may also have a hole injection layer, a hole transport layer, an electron blocking layer, a hole-exciton blocking layer, an electron transport layer, an electron injection layer, and the like. The emissive layer may also be a single layer or a laminate having multiple layers. The hole transport layer and the electron transport layer are also called charge transport layers.

[0031] The first electrode, the light-emitting layer, and the transport layer placed between them all function to transport charge together; therefore, these layers can be treated collectively as the first charge transport layer. Similarly, the second electrode, the light-emitting layer, and the transport layer placed between them all function to transport charge together; therefore, these layers can be treated collectively as the second charge transport layer. Consequently, one surface of the light-emitting layer is in contact with the first charge transport layer, while the other surface is in contact with the second charge transport layer.

[0032] The thickness of each layer in the organic compound layer is usually preferably 1 nm to 10 μm. In particular, the film thickness of the light-emitting layer in the organic compound layer is preferably 10 nm to 100 nm in order to obtain effective light-emitting properties.

[0033] (Luminescent organic compounds) The luminescent layer contained within the organic compound layer contains a luminescent organic compound. Examples of luminescent organic compounds include phosphorescent materials and fluorescent materials. The luminescent organic compound may be a low-molecular-weight material, a high-molecular-weight material, or a mixture thereof. Specific examples of luminescent organic compounds are listed below, but the structure is not limited to these.

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[0046] (Host / Assist Materials) Examples of host or assist materials included in the organic compound layer include the following: aromatic hydrocarbon compounds or their derivatives, as well as polymers such as carbazole derivatives, dibenzofuran derivatives, dibenzothiophene derivatives, triazine derivatives, organoaluminum complexes such as tris(8-quinolinolate)aluminum, organoberylium complexes, polyphenylene derivatives, polyphenylenevinylene derivatives, polyfluorene derivatives, polyvinylcarbazole derivatives, and copolymers or mixtures thereof.

[0047] In addition, as an assisting material, other luminescent organic compounds with a lower minimum excitation triplet energy or lower minimum excitation singlet energy than the aforementioned luminescent organic compound can also be used.

[0048] The following are specific examples of compounds used as host and assist materials, but the structures of host and assist materials are not limited to these.

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[0051] (Hole injection material and hole transport material) The hole implantation layer and hole transport layer, respectively, contained within the organic compound layer, are preferably made of materials with high hole mobility to facilitate hole implantation from the anode and to transport the implanted holes to the light-emitting layer. Furthermore, the minimum excited triplet energy of the hole implantation material or hole transport material is preferably greater than the minimum excited triplet energy of the host and assist materials of the light-emitting layer. Additionally, the minimum excited singlet energy is preferably greater than the minimum excited singlet energy of the host and assist materials of the light-emitting layer.

[0052] Furthermore, in order to reduce the degradation of properties due to crystallization etc. in organic light-emitting elements, materials with a high glass transition temperature are preferred. Examples of low-molecular-weight and high-molecular-weight materials having hole implantation or hole transport properties include triarylamine derivatives, arylcarbazole derivatives, phenylenediamine derivatives, triazole derivatives, oxadiazole derivatives, imidazole derivatives, stilbene derivatives, phthalocyanine derivatives, porphyrin derivatives, polyarylamine derivatives, polyvinylcarbazole derivatives, polythiophene derivatives, conductive polymers such as PEDOT-PSS, and copolymers or mixtures thereof. Moreover, the above-mentioned hole implantation or hole transport materials are also suitably used in electron blocking layers.

[0053] The following are specific examples of compounds used as hole injection materials or hole transport materials, but are not limited to these.

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[0056] (Electron transport materials and electron injection materials) The electron transport material constituting the electron transport layer can be arbitrarily selected from those capable of transporting electrons injected from the cathode to the light-emitting layer. The electron transport material is selected considering the balance with the hole mobility of the hole transport material. Examples of electron transport materials include oxadiazole derivatives, pyrazine derivatives, triazole derivatives, triazine derivatives, quinoline derivatives, quinoxaline derivatives, phenanthroline derivatives, organoaluminum complexes, and fused ring compounds (e.g., fluorene derivatives, naphthalene derivatives, chrysene derivatives, anthracene derivatives, etc.). Furthermore, the above electron transport materials can also be suitably used in the hole blocking layer.

[0057] The following are some specific examples of compounds used as electron transport materials, but of course, they are not the only ones.

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[0059] The electron injection material constituting the electron injection layer can be arbitrarily selected from those that allow for easy electron injection from the cathode, taking into consideration factors such as the balance with hole injection properties. Electron injection materials include n-type dopants and reducing dopants. Examples include alkali metal compounds such as lithium fluoride, lithium complexes such as lithium quinolinol, benzimidazolidene derivatives, imidazolidene derivatives, fulvalene derivatives, and acridine derivatives.

[0060] <Pixel Circuit> The organic light-emitting device may have a pixel circuit connected to an organic light-emitting element. The pixel circuit is preferably an active-matrix type that independently controls the light emission of each of the multiple organic light-emitting elements. The active-matrix circuit may be voltage-programmed or current-programmed. The drive circuit has a pixel circuit for each pixel. The pixel circuit may further include a transistor for controlling the light emission brightness of the organic light-emitting element, a transistor for controlling the light emission timing, a capacitor for holding the gate voltage of the transistor controlling the light emission brightness, and a transistor for connecting to ground without going through the organic light-emitting element.

[0061] The organic light-emitting device has a display area and a peripheral area arranged around the display area. The display area has a pixel circuit, and the peripheral area has a display control circuit. The mobility of the transistors constituting the pixel circuit may be smaller than the mobility of the transistors constituting the display control circuit. The slope of the current-voltage characteristic of the transistors constituting the pixel circuit may be smaller than the slope of the current-voltage characteristic of the transistors constituting the display control circuit. The slope of the current-voltage characteristic can be measured by the so-called Vg-Ig characteristic. The transistors constituting the pixel circuit are transistors connected to the organic light-emitting element.

[0062] <Pixel> The organic light-emitting device has multiple pixels. Each of the multiple pixels has sub-pixels that emit light of a different color from the others. Each sub-pixel independently has a light-emitting color of red (R), green (G), and blue (B). The pixels emit light in a region also called the pixel aperture. The pixel aperture is preferably 15 μm or less, and preferably 5 μm or more. The pixel aperture can be, for example, 11.0 μm, 9.5 μm, 7.4 μm, 6.4 μm, etc. The distance between sub-pixels is preferably 10 μm or less. The distance between sub-pixels can be, for example, 8.0 μm, 7.4 μm, 6.4 μm, etc.

[0063] The planar arrangement of pixels can be a known form. Specifically, examples include stripe arrangement, delta arrangement, pentile arrangement, and Bayer arrangement. The planar shape of subpixels can be a known shape. Specifically, examples include rectangles, rhombuses, and other quadrilaterals and hexagons. Here, the planar shape of a subpixel does not need to be an exact shape; if it is close to a rectangle, it will be judged as a rectangle. The planar shape of subpixels and the pixel arrangement can be used in combination.

[0064] <Liquid composition> In this invention, an organic compound layer is formed by applying a liquid composition, obtained by dissolving, dispersing, or melting an organic compound in a solvent or the like, to a substrate (coating method). Hereinafter, the liquid composition will also be referred to as ink. It is preferable to appropriately control the composition and physical properties of the ink in order to impart a desired function to the organic compound layer and to be compatible with the film-forming process. Examples of materials applicable to inks that can form an organic compound layer include hole injection materials, hole transport materials, organic phosphorescent materials, organic fluorescent materials, host materials, electron transport materials, and electron injection materials.

[0065] The solvent component (liquid component) contained in the ink preferably has a boiling point of 70°C to 300°C at 1 atmosphere. Examples of solvent components include organic solvents such as toluene, xylene, mesitylene, chlorobenzene, tetrahydrofuran, diethylene glycol dimethyl ether, N,N-dimethylformamide, propylene glycol methyl ether acetate, acetonitrile, methanol, ethanol, dichloromethane, chloroform, or water. The content (mass%) of the solvent component contained in the ink is preferably 10.0 times or more and 1000.0 times or less by mass ratio to the total content (mass%) of the organic compound layer material constituting a single organic compound layer.

[0066] The surface tension of the ink can be adjusted by appropriately determining the type and content of the solvent components. At 25°C, the surface tension of the ink is preferably 15 mN / m to 75 mN / m, and more preferably 25 mN / m to 45 mN / m. The surface tension of the ink refers to the "static surface tension" measured by the plate method. The surface tension of the ink can be measured as static surface tension using, for example, a Wilhelmy type surface tensile meter (product name "Automatic Surface Tensile Meter CBVP-Z", manufactured by Kyowa Interface Science).

[0067] Furthermore, the viscosity of the ink at 25°C is preferably between 0.1 mPa·s and 20.0 mPa·s, and more preferably between 0.5 mPa·s and 10.0 mPa·s. By keeping the viscosity within the above range, clogging and ejection failures in the liquid ejection head during inkjet ejection can be suppressed.

[0068] <Method for manufacturing organic light-emitting elements> The method for manufacturing an organic light-emitting element according to the present invention will be described below. If the organic compound layer is a laminate having multiple layers, the following steps may be repeated sequentially for each of the multiple layers. For example, if the organic compound layer has a first organic compound layer and a second organic compound layer, first, the first organic compound layer is formed by applying a first liquid composition containing the organic compounds constituting the first organic compound layer, a first film formation step, and a first pressurization step. Then, the second organic compound layer is formed by applying a second liquid composition containing the organic compounds constituting the second organic compound layer, a second film formation step, and a second pressurization step.

[0069] (Liquid application process) In the liquid application step, a liquid composition containing a liquid component and an organic compound constituting the organic compound layer is applied. In the liquid application step, the liquid composition is applied to the electrode by a coating method. Specific examples of coating methods include known methods such as spin coating, casting, gravure coating, bar coating, roll coating, wire bar coating, dip coating, spray coating, slit coating, capillary coating, screen printing, flexographic printing, offset printing, and inkjet printing. Among these, spray coating, spin coating, and inkjet printing are preferred. The above methods are preferable in that they enable the homogeneous production of large-area organic light-emitting devices. In particular, it is more preferable to apply the liquid composition to the electrode using the inkjet method, as it allows for the application of any material in any amount at any position. In the first liquid application step, it is preferable to apply a first liquid composition containing a hole-injection material as the organic compound to the electrode. In the second liquid application step, it is preferable to apply a second liquid composition containing a luminescent organic compound as the organic compound to the first organic compound layer.

[0070] (Film forming process) In the film-forming process, the liquid components contained in the liquid composition applied in the liquid application process are evaporated to form an organic compound film containing an organic compound. Heating is preferred as the method for evaporating the liquid components contained in the liquid composition. The conditions of the film-forming process can be appropriately set according to the boiling point and vapor pressure of the solvent, the glass transition point and melting point of the organic compound layer material, etc. It is preferable to evaporate the liquid components in an air or inert gas (nitrogen, argon, etc.) environment. The heating temperature is preferably 60°C to 250°C, more preferably 80°C to 200°C, and the heating time is preferably 5 minutes to 60 minutes. The ambient pressure during heating may be normal pressure (1 atmosphere) or reduced pressure (1 Pa to 0.1 MPa). The various conditions (temperature, pressure, and time) in the film-forming process should be set so as to effectively remove the solvent from the organic compound layer. In the first film-forming process, it is preferable to evaporate the liquid components contained in the first liquid composition containing a hole-injection material as an organic compound to form a first organic compound film containing the hole-injection material. Furthermore, in the second film formation step, it is preferable to evaporate the liquid component contained in the second liquid composition, which contains a luminescent organic compound as an organic compound, in order to form a second organic compound film containing the luminescent organic compound.

[0071] (Pressurization process) In the pressurization process, after the film formation process, a pressurizing means is brought into contact with the organic compound film, and the organic compound film is heated and pressurized to form an organic compound layer. Because the organic compound layer formed in the pressurization process is formed by heating and pressurizing by the pressurizing means, voids are crushed, and the film density can be improved. As a result, the luminous efficiency and device life of the organic light-emitting element are improved. Here, voids refer to air pockets that are created in the layer during the process of removing liquid components contained in the liquid composition in the aforementioned film formation process. In the pressurization process, it is important to apply pressure such that the density ratio (A) / (B) satisfies 1.001 ≤ A / B ≤ 1.200 when comparing the density (A) of the organic compound layer produced by the pressurization process with the density (B) of the organic compound film before the pressurization process.

[0072] The pressurizing process is preferably a method in which pressure is applied by bringing a solid plate into contact with the substrate surface and the organic compound layer surface and sandwiching them, or a method in which pressure is applied while transporting the substrate by sandwiching it with a rotating body. Among these, the pressurizing means is preferably a solid plate or a rotating body. The material of the solid plate and rotating body may be quartz, glass, silicon, metal, polymer material, etc., depending on the characteristics of the organic compound layer to be formed. Furthermore, the solid plate and rotating body may be physically or chemically surface modified or surface-treated in order to facilitate the peeling operation from the contacted organic compound layer.

[0073] The environmental conditions during the pressurization process can be appropriately set according to the glass transition temperature, melting point, hardness, etc., of the organic compound layer material. When forming a first organic compound layer containing a luminescent organic compound as the organic compound, the pressure P1 applied by the pressurizing means to the first organic compound film is preferably 1 kPa or more and 300 kPa or less. When forming a first organic compound layer containing a hole-injection material as the organic compound, the pressure P2 applied by the pressurizing means to the first organic compound film is preferably 2 kPa or more and 5 kPa or less. The ambient temperature during the pressurization process is preferably 25°C or more and 200°C or less, and more preferably 60°C or more and 150°C or less. The pressurization time is preferably 1 minute or more and 120 minutes or less, and more preferably 5 minutes or more and 60 minutes or less. Furthermore, heating the organic compound film during the pressurization process softens the organic compound film, making it easier to crush pores under pressure; therefore, it is more preferable to heat the film when pressurizing during the pressurization process. The environmental pressure during the pressure application process may be normal pressure (0.1 MPa), reduced pressure (1 Pa to 0.1 MPa), or pressurized pressure (0.1 to 10 MPa).

[0074] <Applications of organic light-emitting diodes> Organic light-emitting elements can be used as components in display devices and lighting equipment. Other applications include exposure light sources for electrophotographic image recording devices, backlights for liquid crystal display devices, and light-emitting devices with color filters in a white light source.

[0075] The display device has an image input unit that receives image information from an area CCD, linear CCD, memory card, etc., and an information processing unit that processes the input information. CCD stands for Charge-Coupled Device. The display device may also be an image information processing device that displays the input image on a display unit. Furthermore, the display unit of an imaging device or inkjet recording device may have a touch panel function. Specific examples of drive methods for the touch panel function include infrared, capacitive, resistive, and electromagnetic induction methods. The display device may also be used as the display unit of a so-called hybrid recording device.

[0076] Next, the display device will be described with reference to the drawings. Figure 1(a) is a schematic cross-sectional view of an example of a pixel constituting the display device. The pixel has sub-pixels 10. The sub-pixels 10 are divided into 10R, 10G, and 10B based on their light emission. The emitted color may be distinguished and determined by the wavelength 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 10 using a color filter or the like. Each sub-pixel 10 has a reflective electrode 2 which is a first electrode, an insulating layer 3 covering the end of the reflective electrode 2, an organic compound layer 4 covering the first electrode and the insulating layer, a transparent electrode 5, a protective layer 6, and a color filter 7 on an interlayer insulating layer 1.

[0077] The interlayer insulating layer 1 may have transistors or capacitive elements placed beneath or inside it in the direction shown in the illustration. The transistors and the first electrode may be electrically connected via contact holes or the like (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 and is arranged surrounding the first electrode. The portion where the insulating layer 3 is not placed is in contact with the organic compound layer 4 and becomes a light-emitting region. The organic compound layer 4 has a hole injection layer 41, a hole transport layer 42, a first light-emitting layer 43, a second light-emitting layer 44, and an electron transport layer 45. The second electrode 5 may be a transparent electrode, a reflective electrode, or a semi-transparent electrode. The protective layer 6 reduces the penetration of liquid components such as water into the organic compound layer. The protective layer is shown as a single layer, but may consist of multiple layers. If it consists of multiple layers, it may include inorganic compound layers and organic compound layers. The color filter 7 is divided into 7R, 7G, and 7B according to its color. The color filter may be formed on a planarization film (not shown). Alternatively, the color filter may have a resin protective layer (not shown). Furthermore, the color filter may be formed on the protective layer 6, or it may be bonded to an opposing substrate such as a glass substrate after being provided on it.

[0078] Figure 1(b) is a schematic cross-sectional view showing an example of a display device comprising an organic light-emitting element 26 and a transistor connected to the organic light-emitting element 26. The transistor is an example of an active element. The transistor may also be a thin-film transistor (TFT). The display device 100 in Figure 1(b) consists of a substrate 11 made of glass, silicon, or the like, and an insulating layer 12 provided on top of the substrate 11. An active element 18, such as a TFT, is arranged on top of the insulating layer 12, and the gate electrode 13, gate insulating film 14, and semiconductor layer 15 of the active element are arranged thereon. The TFT 18 consists of a semiconductor layer 15, a drain electrode 16, and a source electrode 17. An insulating film 19 is provided on top of the TFT 18. The anode 21 and source electrode 17 constituting the organic light-emitting element are connected via a contact hole 20 provided in the insulating film. 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 TFT is not limited to the embodiment shown in Figure 1(b). In other words, it is sufficient that the anode or cathode is electrically connected to the TFT source electrode or drain electrode.

[0079] In the display device 100 shown in Figure 1(b), the organic compound layer is depicted as a single layer, but the organic compound layer 22 may consist of 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. In the display device 100 shown in Figure 1(b), a transistor is used as the switching element, but other switching elements may be used instead.

[0080] Furthermore, the transistor used in the display device 100 in Figure 1(b) is not limited to a transistor using a single-crystal silicon wafer, but may also be a thin-film transistor having an active layer on an insulating surface of the substrate. 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.

[0081] The transistors included in the display device 100 in Figure 1(b) may be formed within a substrate such as a silicon substrate. Forming within a substrate means that the transistors are manufactured by processing a substrate such as a silicon substrate. In other words, having transistors within a substrate can be seen as the substrate and transistors being formed as a single unit.

[0082] The organic light-emitting element's luminescence is controlled by a TFT, which is an example of a switching element. By arranging multiple organic light-emitting elements on a surface, an image is displayed based on the luminescence of each element. Note that the switching element is not limited to a TFT; it may also be a transistor made of low-temperature polysilicon or an active matrix driver formed on a substrate such as a silicon substrate. The term "top or inside the substrate" can also be interpreted as "within the substrate." Whether to provide a transistor within the substrate or use a TFT is selected depending on the size of the display area. For example, if the size is about 0.5 inches, it is preferable to provide the organic light-emitting element on a silicon substrate.

[0083] Figure 2 is a schematic diagram representing an example of a display device. The display device 1000 has a touch panel 1003, a display panel 1005, a frame 1006, a circuit board 1007, and a battery 1008 between an upper cover 1001 and a lower cover 1009. Flexible printed circuits (FPCs) 1002 and 1004 are connected to the touch panel 1003 and the display panel 1005. Transistors are printed on the circuit board 1007. If the display device is a portable device, a battery 1008 is provided. Alternatively, the battery 1008 may be provided in a different location.

[0084] The display device may have a color filter having red (R), green (G), and blue (B). The color filter may be arranged in a delta array, a stripe array, or a mosaic array.

[0085] The display device can be used in the display section of a mobile device. In this case, it may have both display and operation functions. Examples of mobile devices include smartphones and other mobile phones, tablets, and head-mounted displays.

[0086] The display device can be used in the display unit of an imaging device having an optical unit with multiple lenses and an image sensor that receives light that has passed 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 an external display unit or a display unit located inside the viewfinder. The imaging device may be a digital camera or a digital video camera. The imaging device may also be called a photoelectric converter.

[0087] Figure 3(a) is a schematic diagram showing an example of an imaging device. The imaging device 1100 includes a viewfinder 1101, a rear display 1102, an operating unit 1103, and a housing 1104. The viewfinder 1101 can use a display device. In that case, the display device may display not only the image to be captured, but also environmental information, imaging instructions, etc. 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 that the subject may be obscured by an obstruction.

[0088] Since the optimal timing for imaging is only a short time, it is preferable to be able to display information quickly. Because organic light-emitting elements have a fast response speed, the display device using the organic light-emitting elements of the present invention can be suitably applied. The imaging device 1100 has an optical section (not shown). The optical section has multiple lenses and forms an image on the image sensor housed in the housing 1104. The focus can be adjusted by adjusting the relative positions of the multiple lenses. This operation can also be performed automatically.

[0089] Figure 3(b) is a schematic diagram representing an example of an electronic device. The electronic device 1200 has a display unit 1201, an operating unit 1202, and a housing 1203. The housing 1203 has a circuit, a printed circuit board with the circuit, a battery, and a communication unit. The operating unit 1202 may be a button or a touch panel type response unit. The operating unit 1202 may also be a biometric recognition unit that recognizes fingerprints to unlock the device. An electronic device having a communication unit can also be called a communication device. The electronic device 1200 may further have a camera function by including a lens and an image sensor. In this case, the image captured by the camera function is displayed on the display unit 1201. Examples of the electronic device 1200 include smartphones and laptop computers.

[0090] Figure 4 is a schematic diagram showing an example of a display device. Figure 4(a) is a display device used as a monitor for televisions, personal computers, etc. The display device 1300 has a frame 1301, a display unit 1302, and a base that supports the display unit 1302. The display unit 1302 uses a light-emitting device. The base 1303 is not limited to the form shown in Figure 4(a), and the lower edge of the frame 1301 may also serve as the base. In addition, the frame 1301 and the display unit 1302 may be curved. The radius of curvature is preferably 5,000 mm or more and 6,000 mm or less.

[0091] Figure 4(b) is a schematic diagram representing another example of a display device. The display device 1310 in Figure 4(b) is configured to be foldable and is a so-called foldable display device. The display device 1310 has a first display unit 1311, a second display unit 1312, a housing 1313, and a bending point 1314. The first display unit 1311 and the second display unit 1312 may be light-emitting devices. The first display unit 1311 and the second display unit 1312 may be a single display device without seams. The first display unit 1311 and the second display unit 1312 can be separated at the bending point. The first display unit 1311 and the second display unit 1312 may each display different images or may display a single image.

[0092] Figure 5(a) is a schematic diagram showing an example of a lighting device. The lighting device 1400 includes a housing 1401, a light source 1402, a circuit board 1403, an optical film 1404, and a light diffusion section 1405. An organic light-emitting element can be used as the light source. The optical filter may be a filter that improves the color rendering of the light source. The light diffusion section effectively diffuses the light from the light source, such as for lighting up, and can deliver light over a wide area. The optical filter and light diffusion section may be provided on the light-emitting side of the lighting. A cover may be provided on the outermost part as needed.

[0093] 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 cool white. Here, "white" refers to a color temperature of approximately 4,200K, and "cool white" refers to a color temperature of approximately 5,000K. The lighting device may have a dimming circuit to adjust the brightness. The lighting device may also have an organic light-emitting element and a power supply circuit connected thereto. The power supply circuit is a circuit that converts AC voltage to DC voltage. The lighting device may have a light-diffusing section or a color filter as a component that transmits the light emitted by the light source. The lighting device may also have a heat dissipation section. The heat dissipation section releases heat from inside the device to the outside, and examples include metals with high specific heat or liquid silicon.

[0094] Figure 5(b) is a schematic diagram of an automobile, which is an example of a mobile vehicle. The automobile has a taillight, which is an example of a lighting device. The automobile 1500 may have a taillight 1501, and the taillight may be configured to illuminate when the brakes are applied or when other actions are taken.

[0095] The tail lamp 1501 may have an organic light-emitting element. The tail lamp may also have a protective member to protect the organic light-emitting element. Any protective member can be suitably used as long as it has a reasonably high strength and is transparent. Among these, it is preferable that it be composed of polycarbonate. A frangic acid derivative or an acrylonitrile derivative may be mixed with the polycarbonate.

[0096] The automobile 1500 may have a body 1503 and windows 1502 attached thereto. The windows may be transparent displays unless they are for checking the front and rear of the automobile. The transparent displays may have organic light-emitting elements. In this case, the constituent materials such as electrodes having the organic light-emitting elements are made of transparent components.

[0097] The mobile entity may be a ship, aircraft, drone, etc. The mobile entity may have a body and a light fixture installed on the body. The light fixture may emit light to indicate the position of the entity. The light fixture has an organic light-emitting element.

[0098] Refer to Figure 6 to describe examples of display device applications. The display device can be applied to systems that can be worn as wearable devices, such as smart glasses, head-mounted displays, and smart contact lenses. The imaging display device used in such applications comprises an imaging device capable of photoelectric conversion of visible light and a display device capable of emitting visible light.

[0099] Referring to Figure 6(a), the eyeglasses 1600 (smart glasses) will be described. An imaging device 1602, such as a CMOS sensor or SPAD sensor, is provided on the front surface of the lens 1601 of the eyeglasses 1600. Here, a CMOS (Complementary Metal-Oxide-Semiconductor) sensor is a solid-state image sensor using complementary metal-oxide-semiconductor. A SPAD (Single Photon Avalanche Diode) sensor is a sensor that has an electronic element that outputs a single large electrical pulse signal through avalanche-like multiplication when a single photon is incident on the pixel. A display device is also provided on the back surface of the lens 1601. The eyeglasses 1600 further includes a control device 1603. The control device 1603 functions as a power supply that provides power to the imaging device 1602 and the display device. The control device 1603 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.

[0100] Referring to Figure 6(b), the eyeglasses 1610 (smart glasses) will be described. The eyeglasses 1610 have a control device 1612, which is equipped with an imaging device equivalent to the imaging device 1602 and a display device. The lens 1611 has an optical system formed therein for projecting light emitted from the imaging device and display device in the control device 1612, and an image is projected onto the lens 1611. 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. Gaze detection may use infrared light. The infrared light emitter emits infrared light towards the user's eyeball that is fixated on 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 planar view, the deterioration of image quality is reduced.

[0101] The eyeglasses 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 an 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.

[0102] 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, the display device determines 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, based on the gaze information. The first field of view area and the second field of view area 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. In other words, the resolution of the second field of view area may be lower than that of the first field of view area.

[0103] 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 field-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.

[0104] 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 line of sight 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 contained in the display device, imaging device, or external device. If contained in an external device, it is transmitted to the display device via communication. When display control is based on visual detection, it is preferably applicable 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.

[0105] As described above, the method for manufacturing an organic light-emitting element of the present invention can improve the film density of the organic compound layer and improve the luminous efficiency and lifespan of the organic light-emitting element. [Examples]

[0106] 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. When the amount of components is stated as "parts" or "%", it refers to mass% unless otherwise specified.

[0107] <Preparation of luminescent layer ink> Each component (in %) shown in Table 1 was mixed, stirred at 25°C for 24 hours, and then filtered using a pore size 0.2 μm filter to prepare each luminescent layer ink (liquid composition).

[0108] [Table 1]

[0109] <Fabrication of organic light-emitting devices> Organic light-emitting devices were fabricated by sequentially depositing an anode, hole injection layer, light-emitting layer, electron transport layer, and cathode on a substrate using the following procedure. As the transparent conductive support substrate (ITO substrate), a glass substrate was used on which ITO was deposited as the anode to a thickness of 100 nm by sputtering. The ITO substrate was washed with pure water, then isopropanol, and after UV-ozone treatment to remove organic matter from the substrate surface, the organic compound layer was deposited under the conditions shown below.

[0110] (Examples 1-8) The following liquid composition for the hole-injection layer was applied to the electrodes of the ITO substrate that had undergone the above treatment by spin coating. Subsequently, the hole-injection layer was formed by annealing (heating) the liquid composition on the substrate without pressurizing it under the following conditions. The conditions for forming the hole-injection layer are as follows. • Liquid composition: Aqueous solution of poly(3,4-ethylenedioxythiophene) polystyrene sulfonic acid (PEDOT; PSS aqueous solution, manufactured by Aldrich, conductivity 1 × 10⁻⁶ -5 S / cm, compound concentration 2.8% by mass) • Spin court conditions: 3,000 rpm, 60 seconds Annealing (heating) conditions: 200°C, 1 hour • Film thickness: 40nm Next, the light-emitting layer inks 1-3 shown in Table 2 were applied to the hole-injection layer by spin coating. Then, the light-emitting layer inks were annealed under the following conditions to form a light-emitting film. The film formation conditions are as follows: • Spin court conditions: 3,000 rpm, 60 seconds Annealing conditions: 110°C, 15 minutes • Film thickness: 30nm A substrate on which a light-emitting film had been fabricated under the above conditions was placed horizontally, and a quartz plate (1 mm thick) was placed parallel to the top surface of the light-emitting film. Annealing was performed under pressure by placing weights on top of the quartz plate (pressure step). The light-emitting layer was formed through this pressure step. The pressure used for pressurization was as shown in Table 2. Annealing was performed simultaneously with pressurization under the following conditions. The quartz plate was washed with pure water and dried with a nitrogen stream before being placed on top of the light-emitting film. Annealing conditions: 110°C, 15 minutes Finally, the electron transport layer and electrode layer (cathode) were fabricated using vacuum deposition with resistance heating. The opposing electrode area was 3 mm². 2 The film deposition conditions were as follows: ·Vacuum degree: 1×10 -5 Pa ·Electron transport layer: TPBi (50nm) ·Metal electrode layer: LiF (0.5nm), Al (90nm) Subsequently, to prevent degradation of the organic light-emitting element due to moisture adsorption, a protective glass plate was placed over the element under a nitrogen atmosphere and sealed with an acrylic resin adhesive.

[0111] (Example 9) An organic light-emitting element was fabricated in the same manner as in Example 6, except that the pressurizing conditions for forming the light-emitting layer were changed as described below. A hole-injection layer was formed under the same conditions as in Example 6, and then the substrate on which the light-emitting film was fabricated was placed horizontally. Furthermore, a silicon roller heated to 110°C was brought into contact with the upper surface of the light-emitting film, and the light-emitting film was pressurized by moving the roller back and forth over the film at a speed of 3 mm / s for 15 minutes while applying a pressure of 2.0 kPa to the light-emitting film, thereby forming the light-emitting layer.

[0112] (Examples 10-13) After depositing the hole-injection film in the same manner as in Example 1, the substrate was placed horizontally, and a quartz plate (1 mm thick) was placed parallel to the top surface of the light-emitting film. Annealing was performed while applying pressure by placing weights on top of the quartz plate. The hole-injection film was pressurized at the pressures shown in Table 2, and annealing was performed simultaneously with the pressurization under the following conditions. The quartz plate was washed with pure water and dried with a nitrogen stream before being placed on top of the hole-injection film. Annealing conditions: 110°C, 15 minutes Next, similar to Example 1, a substrate with a light-emitting film fabricated on a hole-injection film was placed horizontally, and a quartz plate (1 mm thick) was placed parallel to the top surface of the light-emitting film. Annealing was performed while applying pressure by placing weights on the quartz plate. This pressurization process formed the light-emitting layer. The pressure applied was as shown in Table 2, and annealing was performed simultaneously with the pressurization under the same conditions as in Example 1. After that, an electron transport layer and an electrode layer were fabricated in the same manner as in Example 1, a protective glass plate was placed over the organic light-emitting element in a nitrogen atmosphere, and it was sealed with an acrylic resin adhesive.

[0113] (Examples 14-18) An organic light-emitting element was fabricated in the same manner as in Example 10, except that the pressure in the pressurization process when forming the hole injection layer and the light-emitting layer, and the light-emitting layer ink were changed as shown in Table 2.

[0114] (Example 19) An organic light-emitting element was fabricated in the same manner as in Example 10, except that the pressurization conditions for the hole-injection film were changed as follows. The substrate on which the hole-injection film was deposited under the same conditions as in Example 10 was placed horizontally. Furthermore, a silicon roller heated to 110°C was brought into contact with the upper surface of the hole-injection film, and the hole-injection film was pressurized by reciprocating it over the film at a speed of 3 mm / s for 15 minutes while applying a pressure of 2 kPa to the film. The hole-injection layer was formed through this pressurization process.

[0115] (Examples 20-23) An organic light-emitting element was fabricated in the same manner as in Example 10, except that a pressurization step was omitted when forming the light-emitting layer, and the pressure and light-emitting layer ink used in the pressurization step when forming the hole-injection layer were changed as shown in Table 2.

[0116] (Example 24) An organic light-emitting element was fabricated in the same manner as in Example 19, except that a pressurization step was not performed when forming the light-emitting layer.

[0117] (Comparative Examples 1-3) An organic light-emitting element was fabricated under the same conditions as in Example 1, except that a pressurization step was not performed when forming the light-emitting layer, and the light-emitting layer ink was changed as shown in Table 2.

[0118] (Comparative Example 4) An organic light-emitting device was fabricated in the same manner as in Example 1, except that the following steps were performed without a pressurization step when forming the light-emitting layer. The light-emitting film was fabricated in the same manner as in Example 1, and then the atmospheric pressure was set to 10 × 10 in a vacuum drying oven. -4 The pressure was reduced to Pa, and annealing was performed under the following conditions. Afterwards, the ambient pressure was increased to atmospheric pressure and the pressure reduction was released. Annealing conditions: 35°C, 20 minutes (Comparative Example 5) An organic light-emitting element was fabricated in the same manner as in Comparative Example 4, except that the following steps were performed after the formation of the hole-injection layer. The hole-injection layer was formed in the same manner as in Comparative Example 4, and then the atmospheric pressure was set to 10 × 10 in a vacuum drying oven. -4 The pressure was reduced to Pa, and annealing was performed under the following conditions. After that, the ambient pressure was increased to atmospheric pressure. Annealing conditions: 35°C, 20 minutes (Comparative Example 6) An organic light-emitting element was fabricated in the same manner as in Example 20, except that the following steps were performed without a pressurization step when forming the hole-injection layer. The hole-injection film was fabricated in the same manner as in Example 20, and then the atmospheric pressure was set to 10 × 10 in a vacuum drying oven. -4 The pressure was reduced to Pa, and annealing was performed under the following conditions. After that, the ambient pressure was increased to atmospheric pressure. Annealing conditions: 35°C, 20 minutes <Rating> The organic light-emitting element fabricated as described above was evaluated for the following items. In this invention, "AA," "A," and "B" were defined as acceptable levels, and "C" as an unacceptable level in the evaluation criteria for each of the following items. The evaluation results are shown in Table 2.

[0119] (density ratio) The density (A) of the organic compound layer, including the hole-injection layer and light-emitting layer, of the organic light-emitting devices fabricated in Examples 1-24 and Comparative Examples 4-6 was measured using an XRR measuring device (product name "ATX-G", manufactured by Rigaku). Similarly, the density (B) of the organic compound layer, including the hole-injection layer and light-emitting layer, of the organic light-emitting devices fabricated in Comparative Examples 1-3, which were fabricated without a pressurization process, was measured using the same method. The density ratio (A) / (B) was calculated from the obtained densities (A) and (B), and evaluated according to the evaluation criteria shown below. The density ratios for Examples 1-4, 8, 10-17, 19-22, 24, and Comparative Examples 4-6 were calculated using the density (A) of each example and the density (B) of Comparative Example 1. The density ratios for Examples 5, 7, 18, and 23 were calculated using the density (A) of each example and the density (B) of Comparative Example 2. The density ratios for Examples 6 and 9 were calculated using the density (A) of each example and the density (B) of Comparative Example 3. For Comparative Examples 1 to 3, the density ratio (A) / (B) was calculated using the same Comparative Examples 1 to 3, resulting in a density ratio of 1.000 in all cases.

[0120] AA: The density ratio was greater than 1.020 and less than or equal to 1.200. A: The density ratio was greater than 1.005 and less than or equal to 1.020. B: The density ratio was greater than 1.001 and less than or equal to 1.005. C: The density ratio was less than 1.001.

[0121] (Luminous efficiency ratio) The luminous efficiency ratios of the organic light-emitting elements fabricated in Examples 1-24 and Comparative Examples 4-6 were calculated using the following method. First, for the organic light-emitting elements fabricated in Examples 1-24 and Comparative Examples 4-6, the ITO electrode was used as the anode and the Al electrode as the cathode, and IVL (current-voltage-luminance) measurements were performed using a spectroradiometer (product name "SR-LEDW", manufactured by Topcon Techno House). From this measurement, the luminous efficiency ratio of 10 mA / cm² for each organic light-emitting element was calculated. 2 The luminous efficiency (external quantum efficiency) (C) was measured. Similarly, the luminous efficiency (D) of the organic light-emitting devices fabricated in Comparative Examples 1 to 3 was measured. The luminous efficiency ratio (C) / (D) was calculated from the obtained luminous efficiency (C) and luminous efficiency (D), and evaluated according to the evaluation criteria shown below. The luminous efficiency ratios for Examples 1 to 4, 8, 10 to 17, 19 to 22, 24, and Comparative Examples 4 to 6 were calculated using the luminous efficiency (C) of each example and the luminous efficiency (D) of Comparative Example 1. The luminous efficiency ratios for Examples 5, 7, 18, and 23 were calculated using the luminous efficiency (C) of each example and the luminous efficiency (D) of Comparative Example 2. The luminous efficiency ratios for Examples 6 and 9 were calculated using the luminous efficiency (C) of each example and the luminous efficiency (D) of Comparative Example 3. For Comparative Examples 1 to 3, the luminous efficiency ratio (C) / (D) was calculated using the same Comparative Examples 1 to 3, so the luminous efficiency ratio was 1.000 in all cases.

[0122] AA: The luminous efficiency ratio exceeded 1.2. A: The luminous efficiency ratio was greater than 1.1 and less than or equal to 1.2. B: The luminous efficiency ratio was greater than 1.001 and less than or equal to 1.1. C: The luminous efficiency ratio was 1.001 or less.

[0123] (Element lifetime ratio) For the organic light-emitting elements fabricated in Examples 1-24 and Comparative Examples 4-6, the initial brightness when energized at 20 mA / cm² was set to 100%, and 20 mA / cm² 2The device lifespan (E) was defined as the durability time (LT80) until the brightness reached 80% during continuous operation. The device lifespan (E) was then measured using an OLED lifespan evaluation device (product name "EAS-26F", manufactured by System Giken). Similarly, the device lifespan (F) of the organic light-emitting elements fabricated in Comparative Examples 1 to 3 was measured. The device lifespan ratio (E) / (F) was calculated from the obtained device lifespan (E) and device lifespan (F), and evaluated according to the evaluation criteria shown below. The device lifespan ratios for Examples 1 to 4, 8, 10 to 17, 19 to 22, 24, and Comparative Examples 4 to 6 were calculated using the device lifespan (E) of each example and the device lifespan (F) of Comparative Example 1. The device lifespan ratios for Examples 5, 7, 18, and 23 were calculated using the device lifespan (E) of each example and the device lifespan (F) of Comparative Example 2. The device lifespan ratios for Examples 6 and 9 were calculated using the device lifespan (E) of each example and the device lifespan (F) of Comparative Example 3. For Comparative Examples 1 to 3, the device lifetime ratio (C) / (D) was calculated using the same Comparative Examples 1 to 3, resulting in a device lifetime ratio of 1.000 in all cases.

[0124] AA: The element lifetime ratio exceeded 1.5. A: The element lifetime ratio was greater than 1.3 and less than or equal to 1.5. B: The element lifetime ratio was greater than 1.001 and less than or equal to 1.3. C: The element lifetime ratio was 1.001 or less.

[0125] [Table 2]

[0126] Furthermore, the disclosure of this embodiment includes the following methods.

[0127] (Method 1) A method for manufacturing an organic light-emitting element, comprising a pair of electrodes and an organic compound layer disposed between the electrodes on a substrate, A liquid application step involves applying a liquid composition containing a liquid component and an organic compound constituting the organic compound layer onto the electrode formed on the substrate, A film-forming step involves evaporating the liquid components contained in the liquid composition applied to the electrode by the liquid application step to form an organic compound film containing the organic compound, The process includes, after the film formation step, a pressurizing step in which a pressurizing means is brought into contact with the organic compound film, and the organic compound film is heated and pressurized to form the organic compound layer, A method for manufacturing an organic light-emitting element, characterized in that the ratio of the density (A) of the organic compound layer produced through the pressurization step to the density (B) of the organic compound layer produced without the pressurization step satisfies the following formula (1).

[0128] 1.001 ≤ A / B ≤ 1.200 (1) (Method 2) The method for producing an organic light-emitting element according to Method 1, wherein the organic compound includes a luminescent organic compound.

[0129] (Method 3) The method for manufacturing an organic light-emitting element according to Method 2, wherein the pressure applied by the pressurizing means to the organic compound film is 1 kPa or more and 300 kPa or less.

[0130] (Method 4) The method for producing an organic light-emitting element according to Method 1, wherein the organic compound comprises a hole-injection material.

[0131] (Method 5) The method for manufacturing an organic light-emitting element according to Method 4, wherein the pressure applied by the pressurizing means to the first organic compound film is 2 kPa or more and 5 kPa or less.

[0132] (Method 6) The organic compound layer comprises a hole-injection layer containing a hole-injection material and a light-emitting layer containing a light-emitting organic compound. The aforementioned hole injection layer is A first liquid application step involves applying a first liquid composition containing a first liquid component and the hole injection material to the electrode formed on the substrate, A first film formation step involves evaporating the first liquid component contained in the first liquid composition applied to the electrode by the first liquid application step to form a hole-injection film containing the hole-injection material, The hole-injection layer is formed by a first pressurization step, in which, after the first film-forming step, a pressurizing means is brought into contact with the hole-injection film, and the hole-injection film is heated and pressurized to form the hole-injection layer. The aforementioned light-emitting layer is Following the first pressurization step, a second liquid application step is performed in which a second liquid composition containing a second liquid component and the luminescent organic compound is applied to the hole injection layer. A second film formation step involves evaporating the second liquid component contained in the second liquid composition applied onto the hole injection layer by the second liquid application step to form a light-emitting film containing the light-emitting organic compound, A method for manufacturing an organic light-emitting element according to Method 1, comprising: a second pressurization step in which, after the second film-forming step, the pressurizing means is brought into contact with the light-emitting film, and the light-emitting film is heated and pressurized to form the light-emitting layer.

[0133] (Method 7) The method for manufacturing an organic light-emitting element according to any one of methods 1 to 6, wherein the pressurizing means is a solid plate or a rotating body. [Explanation of Symbols]

[0134] 4 Organic compound layer 7 Color Filters 10 subpixels 11 circuit boards 16 Drain electrode 17 Source electrodes 18 Active elements 21 Anode 22 Organic compound layer 23 Cathode 26 Organic light-emitting diodes

Claims

1. A method for manufacturing an organic light-emitting element, comprising a pair of electrodes and an organic compound layer disposed between the electrodes on a substrate, A liquid application step involves applying a liquid composition containing a liquid component and an organic compound constituting the organic compound layer onto the electrode formed on the substrate, A film-forming step involves evaporating the liquid components contained in the liquid composition applied to the electrode by the liquid application step to form an organic compound film containing the organic compound, The process includes, after the film formation step, a pressurizing step in which a pressurizing means is brought into contact with the organic compound film, and the organic compound film is heated and pressurized to form the organic compound layer, A method for manufacturing an organic light-emitting element, characterized in that the ratio of the density (A) of the organic compound layer produced through the pressurization step to the density (B) of the organic compound layer produced without the pressurization step satisfies the following formula (1). 1.001 ≤ A / B ≤ 1.200 (1)

2. The method for producing an organic light-emitting element according to claim 1, wherein the organic compound includes a luminescent organic compound.

3. The method for manufacturing an organic light-emitting element according to claim 2, wherein the pressure applied by the pressurizing means to the organic compound film is 1 kPa or more and 300 kPa or less.

4. The method for producing an organic light-emitting element according to claim 1, wherein the organic compound comprises a hole-injection material.

5. The method for manufacturing an organic light-emitting element according to claim 4, wherein the pressure applied by the pressurizing means to the organic compound film is 2 kPa or more and 5 kPa or less.

6. The organic compound layer comprises a hole-injection layer containing a hole-injection material and a light-emitting layer containing a light-emitting organic compound. The aforementioned hole injection layer is A first liquid application step involves applying a first liquid composition containing a first liquid component and the hole injection material to the electrode formed on the substrate, A first film formation step involves evaporating the first liquid component contained in the first liquid composition applied to the electrode by the first liquid application step to form a hole-injection film containing the hole-injection material, The film is formed by a first pressurization step, in which, after the first film formation step, a pressurizing means is brought into contact with the hole-injection film, and the hole-injection film is heated and pressurized to form the hole-injection layer. The aforementioned light-emitting layer is Following the first pressurization step, a second liquid application step is performed in which a second liquid composition containing a second liquid component and the luminescent organic compound is applied to the first hole injection layer. A second film formation step involves evaporating the second liquid component contained in the second liquid composition applied onto the hole injection layer by the second liquid application step to form a light-emitting film containing the light-emitting organic compound, A method for manufacturing an organic light-emitting element according to claim 1, comprising: a second pressurization step, after the second film-forming step, bringing the pressurizing means into contact with the light-emitting film, heating and pressurizing the light-emitting film to form the light-emitting layer.

7. The method for manufacturing an organic light-emitting element according to claim 1, wherein the pressurizing means is a solid plate or a rotating body.

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