Method for manufacturing an organic light-emitting element, and apparatus for manufacturing an organic light-emitting element

Abstract

To provide a method for manufacturing an organic light-emitting element that reduces color mixing between different pixel regions, suppresses variations in the thickness of the light-emitting layer between pixel regions, and suppresses non-uniformity of the shape of the light-emitting layer within a pixel region. [Solution] A method for manufacturing an organic light-emitting element, comprising: a first liquid application step of applying a first liquid composition containing a first light-emitting material to a first pixel region; a first drying step of drying the inside of the first pixel region; a second liquid application step of applying a second liquid composition containing a second light-emitting material different from the first light-emitting material to a second pixel region; a vapor exposure step of exposing the first and second pixel regions to vapor of a solvent capable of dissolving the first and second light-emitting materials; and a second drying step of drying the inside of the first and second pixel regions, wherein the volume of the first liquid composition applied to the first pixel region is greater than the volume of the first pixel region, and the volume of the second liquid composition applied to the second pixel region is greater than the volume of the second pixel region.

Description

Technical Field

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

Background Art

[0002] An organic light-emitting device is an electronic device having a pair of electrodes of a first electrode and a second electrode, and an organic compound layer disposed between the pair of electrodes. As a method for manufacturing an organic light-emitting device, a method of forming films of a light-emitting material, a charge transport material, a charge injection material, etc. and laminating them is known. Hereinafter, materials for forming an organic compound layer of an organic light-emitting device such as a light-emitting material, a charge transport material, and a charge injection material are collectively referred to as functional materials. The vapor deposition method is widely used in the method for manufacturing an organic light-emitting device. For example, when forming a light-emitting layer containing a light-emitting material on a substrate, a light-emitting material capable of emitting light in red, green, blue, etc. is vapor-deposited on the substrate by vacuum vapor deposition to form a film of the light-emitting layer. When manufacturing an organic light-emitting device by the vapor deposition method, it is necessary to form a pattern that divides the film-forming part and the non-film-forming part using a mask. However, in the non-film-forming part, since the functional material is vapor-deposited on the mask, there is a problem with the utilization rate of the functional material.

[0003] In recent years, a coating method has been considered as a method for manufacturing an organic light-emitting device that can solve the above problems in the vapor deposition method. In the coating method, a liquid composition containing a functional material is applied to a substrate to manufacture an organic light-emitting device. As a coating method, for example, a method of coating a liquid composition on a substrate by an inkjet method is being considered. In the case of the inkjet method, the liquid composition can be selectively applied to the film-forming part, and waste of the functional material in the non-film-forming part can be reduced, so the utilization rate of the functional material is improved, and it is considered to have an advantage in terms of cost compared to the vapor deposition method.

[0004] In the coating method, pixel regions are separated by enclosing them on all four sides with partitions, and a liquid composition containing a functional material is applied within the partitions. However, if liquid compositions applied to different pixel regions, especially adjacent pixel regions, come into contact and mix, it can cause issues such as color mixing. Therefore, various measures to suppress the mixing of liquid compositions are being considered. Patent Document 1 discloses a method in which a small amount of a liquid composition containing a functional material is applied to a region enclosed by partitions, and areas where filling defects occur are exposed to the vapor of a low-boiling point solvent to wet and spread the liquid composition throughout the region. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2012-248297 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] When the inventors applied a liquid composition containing a light-emitting material to a pixel region using the method described in Patent Document 1 to form a light-emitting layer, it was found that there was variation in the thickness of the formed light-emitting layer. In particular, it was found that there was variation in the thickness of the light-emitting layer formed in different pixel regions. It was also found that the shape of the light-emitting layer formed within a single pixel region was non-uniform. Therefore, the present invention aims to provide a method for manufacturing an organic light-emitting element that reduces color mixing between different pixel regions, suppresses variations in the thickness of the light-emitting layer between pixel regions, and suppresses non-uniformity of the shape of the light-emitting layer within a pixel region. [Means for solving the problem]

[0007] The above objective is achieved by the present invention as follows: a first liquid application step of applying a first liquid composition containing a first light-emitting material to a first pixel region surrounded by a partition on a substrate; a first drying step of drying the inside of the first pixel region after the first liquid application step; a second liquid application step of applying a second liquid composition containing a second light-emitting material different from the first light-emitting material to a second pixel region adjacent to the first pixel region and surrounded by a partition on the substrate after the first drying step; and after the second liquid application step, exposing the first and second pixel regions to vapor of a solvent in which both the first and second light-emitting materials can be dissolved. A method for manufacturing an organic light-emitting element, comprising: a vapor exposure step; and a second drying step, after the vapor exposure step, drying the first and second pixel regions to form a first light-emitting layer containing the first light-emitting material in the first pixel region and a second light-emitting layer containing the second light-emitting material in the second pixel region, characterized in that the volume of the first liquid composition applied to the first pixel region in the first liquid application step is greater than the volume of the first pixel region, and the volume of the second liquid composition applied to the second pixel region in the second liquid application step is greater than the volume of the second pixel region. [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 reduces color mixing between different pixel regions, suppresses variations in the thickness of the light-emitting layer between pixel regions, and suppresses non-uniformity of the shape of the light-emitting layer within a pixel region. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram of an organic light-emitting element substrate. [Figure 2] This is a schematic diagram illustrating the mechanism by which color mixing occurs on an organic light-emitting element substrate. [Figure 3] This is a schematic diagram illustrating the mechanism by which non-uniformity of the light-emitting layer shape occurs within the pixel region. [Figure 4] This is a schematic diagram of an organic light-emitting element substrate and ink application. [Figure 5] This is an example of the shape of the first light-emitting layer formed within the pixel region. [Figure 6] This is an example of the shape of the first light-emitting layer formed within the pixel region. [Figure 7] This is a schematic diagram showing the process of forming the light-emitting layer according to this embodiment. [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 of the present invention investigated a method for manufacturing an organic light-emitting element that can reduce color mixing between different pixel regions, suppress variations in the thickness of the light-emitting layer between pixel regions, and suppress non-uniformity of the shape of the light-emitting layer within a pixel region. As a result, they found that this problem can be solved by the following configuration, leading to the present invention.

[0012] In other words, the method for manufacturing an organic light-emitting element according to the present invention comprises a first liquid application step, a first drying step, a second liquid application step, a vapor exposure step, and a second drying step. In the first liquid application step, a first liquid composition containing a first light-emitting material is applied to a first pixel region surrounded by a partition on a substrate. In the first drying step, the first pixel region is dried after the first liquid application step. In the second liquid application step, a second liquid composition containing a second light-emitting material different from the first light-emitting material is applied to a second pixel region adjacent to the first pixel region and surrounded by a partition on the substrate, after the first drying step. In the vapor exposure step, the first and second pixel regions are exposed to vapor of a solvent capable of dissolving both the first and second light-emitting materials after the second liquid application step. In the second drying step, the first and second pixel regions are dried after the vapor exposure step to form a first light-emitting layer containing the first light-emitting material in the first pixel region and a second light-emitting layer containing the second light-emitting material in the second image region, respectively. Furthermore, the volume of the first liquid composition applied to the first pixel region in the first liquid application step is greater than the volume of the first pixel region, and the volume of the second liquid composition applied to the second pixel region in the second liquid application step is greater than the volume of the second pixel region.

[0013] Furthermore, the organic light-emitting device according to the present invention comprises a first liquid application means, a first drying means, a second liquid application means, a vapor exposure means, and a second drying means. The first liquid application means is a device for applying a first liquid composition containing a first light-emitting material to a first pixel region surrounded by a partition on a substrate. The first drying means is a device for drying the first pixel region after the application of the first liquid composition by the first liquid application means. The second liquid application means is a device for applying a second liquid composition containing a second light-emitting material different from the first light-emitting material to a second pixel region adjacent to the first pixel region and surrounded by a partition on the substrate, after drying by the first drying means. The vapor exposure means is a device for exposing the first and second pixel regions to vapor of a solvent capable of dissolving both the first and second light-emitting materials after the application of the second liquid composition by the second liquid application means. The second drying means is an apparatus that dries the first and second pixel regions after steam exposure by the steam exposure means, thereby forming a first light-emitting layer containing a first light-emitting material in the first pixel region and a second light-emitting layer containing a second light-emitting material in the second image region.

[0014] With the above configuration, color mixing between different pixel regions can be reduced, variations in the thickness of the light-emitting layer between pixel regions can be suppressed, and non-uniformity of the shape of the light-emitting layer within a pixel region can be prevented. The reason why the effects of the present invention can be obtained with this configuration will be explained in detail below.

[0015] The inventors first investigated the phenomenon of differences in the thickness of light-emitting layers when a liquid composition is applied to different pixel regions and a light-emitting layer is formed in each region. As a result, they found that the smaller the volume of liquid composition applied to each pixel region, the greater the tendency for differences in the thickness of the light-emitting layers to occur. The inventors speculate on this phenomenon as follows.

[0016] As described in Patent Document 1, when a liquid dispensing device is used to dispense a liquid composition from a nozzle and apply the liquid composition to a pixel area in the form of droplets, a volume difference occurs between each droplet. This is a common phenomenon caused by variations in the liquid filling state within the nozzle and variations in the driving force of the element that dispenses the droplets. For example, the average volume of a droplet dispensed from the nozzle of a liquid dispensing device is considered to be 2 pL per droplet, and a maximum volume difference of 1 pL can occur. When one drop of liquid composition is applied to a single pixel area to form a light-emitting layer, the droplets applied to different pixel areas will be formed with a maximum volume difference of 1 pL. Considering that the average volume is 2 pL, a difference of 1 pL is 50% of the average volume. On the other hand, when multiple drops of liquid composition are applied to a single pixel area, droplets with a volume larger than the average volume and droplets with a volume smaller than the average volume are mixed and applied to the pixel area, and the volume differences between the droplets are averaged out. In this case, the volume of the liquid composition contributing to the formation of the light-emitting layer is the sum of the volumes of multiple droplets, and as a result, the difference in the total volume of the liquid composition applied to different pixel regions tended to be small. The thickness of the light-emitting layer depends on the volume of the liquid composition applied to each pixel region, and the larger the volume difference, the larger the difference in the thickness of the light-emitting layer.

[0017] For example, let's consider a case where the average volume of droplets discharged from a liquid dispensing device is 2.0 pL per drop, and one drop of the liquid composition is applied to each of the different pixel regions. Let's call these pixel regions pixel region 1, pixel region 2, pixel region 3, pixel region 4, and pixel region 5, and assume that the volumes of the liquid composition applied to pixel regions 1-5 are 2.5 pL, 1.9 pL, 1.8 pL, 2.3 pL, and 1.5 pL, respectively. In this case, the volume of the liquid composition applied to pixel region 1 is the largest, and the volume of the liquid composition applied to pixel region 5 is the smallest, with a volume difference of 1.0 pL. In this way, when one drop of the liquid composition is applied to each pixel region, comparing the average volume of droplets discharged from the liquid dispensing device with the volume of the liquid composition droplets applied to each pixel region, a volume difference of 1.0 pL corresponds to 50%.

[0018] On the other hand, a case where the above-described five droplets of the liquid composition are applied to the pixel region 1 and similarly five droplets of the liquid composition are applied to the pixel region 2 will be described. The total volume of the droplets of the liquid composition applied to the pixel region 1 is 10.0 pL because it is the total volume of five droplets with volumes of 2.5 pL, 1.9 pL, 1.8 pL, 2.3 pL, and 1.5 pL. Similarly for the pixel region 2, five droplets with an average volume of 2.0 pL are applied, and let the volume of each of the five droplets be 2.4 pL, 1.4 pL, 2.2 pL, 2.3 pL, and 1.7 pL. At this time, the total volume of the droplets of the liquid composition applied to the pixel region 2 is also 10.0 pL, the same as that of the pixel region 1. As described above, by applying a plurality of droplets to one pixel region and increasing the volume of the liquid composition, it is possible to suppress the occurrence of a volume difference for each droplet and reduce the difference in the thickness of the light-emitting layers formed in different pixel regions.

[0019] The inventors of the present invention studied a method of forming a light-emitting layer by applying a liquid composition having a volume exceeding the volume of each pixel region to each of the first pixel region 101 formed on the substrate 100 shown in FIG. 1 and the second pixel region 102 adjacent to the first pixel region 101. The application of the liquid composition to each pixel region is performed by discharging droplets from the discharge port of the liquid ejection device to the pixel region, and the number of droplets of the liquid composition applied to each pixel region is the same. As a result, when the second liquid composition is applied to the second pixel region 102 without drying the first liquid composition after the first liquid composition is applied to the first pixel region 101, it was found that the first liquid composition and the second liquid composition are mixed in color on the upper surface of the partition wall 103 of the substrate 100. This is because the overflowing liquid compositions come into contact with each other on the upper surface of the partition wall 103 as shown in FIG. 2. This phenomenon is more likely to occur as the distance between pixel regions is made closer in order to achieve high definition of the organic light-emitting device. On the other hand, it was found that no color mixing occurs when a volume of the first liquid composition exceeding the volume of the first pixel region 101 is applied to the first pixel region 101, the first liquid composition is dried, and then a volume of the second liquid composition exceeding the volume of the second pixel region 102 is applied to the second pixel region 102.

[0020] The mechanism will be described with reference to FIGS. 3(a) to 3(c). The volume of the first liquid composition applied to the first pixel region is larger than the volume of the first pixel region. Therefore, when the first liquid composition 201 is applied to the first pixel region 101, the first liquid composition 201 that exceeds the volume of the first pixel region 101 overflows onto the upper surface of the partition wall 103 on the substrate 100 as shown in FIG. 3(a). Then, by drying the inside of the first pixel region in the first drying step, the liquid component in the first liquid composition 201 evaporates, and the dried first liquid composition as shown in FIG. 3(b) fits within the first pixel region 101. Next, the second liquid composition 202 is applied to the second pixel region 102. At this time, the volume of the second liquid composition applied to the second pixel region is larger than the volume of the second pixel region. The second liquid composition 202 overflows onto the upper surface of the partition wall 103 of the substrate 100 as shown in FIG. 3(c). However, since the first liquid composition dried by the above-described first drying step fits within the first pixel region 101, the second liquid composition 202 and the first liquid composition 201 do not come into contact with each other and no color mixing occurs.

[0021] However, it was found that when the first liquid composition 201 is applied to the first pixel region 101 and dried, and then the second liquid composition 202 is applied to the second pixel region 102, a new problem arises: the shape of the light-emitting layer formed in the first pixel region 101 becomes non-uniform. The inventors speculate that the mechanism by which the non-uniformity of the shape of the light-emitting layer within the pixel region occurs is as follows: The first liquid composition 201 is applied to the first pixel region 101 and the inside of the first pixel region 101 is dried, causing the liquid components in the first liquid composition 201 to evaporate. As a result, the dried first liquid composition is contained within the first pixel region 101. Subsequently, the second liquid composition 202 is applied to the second pixel region 102 and the inside of the second pixel region 102 is dried, causing the liquid components in the second liquid composition 202 to evaporate. At this time, vapor from the liquid components of the second liquid composition is present in the region of the first pixel region 101 that is on the side of the second pixel region 102 (the region closer to the second pixel region 102), resulting in uneven vapor concentration on the first pixel region 101. Due to this unevenness, the drying of the first liquid composition 201 in the region of the first pixel region 101 that is on the side of the second pixel region 102 is slower than in the opposite region of the first pixel region 101 (the region further away from the second pixel region 102). Generally, when there is a difference in drying rate within a liquid composition, convection of the liquid components occurs within the liquid composition, and the liquid components and light-emitting material move to the side where drying is progressing faster. In this case, evaporation of the liquid components in the region of the first pixel region opposite to the second pixel region 102 is promoted, and drying progresses faster. This phenomenon causes convection of the first liquid composition 201 to occur in the region of the first pixel region 101 that is opposite to the first pixel region 102. As a result, the thickness of the light-emitting layer formed in the region opposite to the first pixel region 102 in the first pixel region 101 became thicker, which is thought to have caused non-uniformity in the shape of the light-emitting layer within the image region.

[0022] As shown in Figure 4, the inventors applied the first liquid composition 201 to the first pixel region 101, dried it, and then applied the second liquid composition 202 to the second pixel region 102 and dried it further to form the first and second light-emitting layers. For comparison, a sample was prepared in which only the first light-emitting layer was formed by applying the first liquid composition 201 to the first pixel region 101 and drying it. In each case, the film was cut along the line A-A' in Figure 4 and the cross-section was observed. Figure 5 is a schematic diagram of the shape of the first light-emitting layer 501 when both the first and second light-emitting layers were formed by the method described above. The first light-emitting layer 501 was thicker in the direction of the -Y axis in Figure 4. Figure 6 is a schematic diagram of the shape of the first light-emitting layer 601 when only the first light-emitting layer was formed by the method described above. The first light-emitting layer 601 shown in Figure 6 did not show the thickness unevenness of the light-emitting layer that was observed in the first light-emitting layer 501 shown in Figure 5. When light is emitted by electroluminescence, the current concentrates in areas with low resistance, i.e., in areas where the light-emitting layer is thin. Therefore, if there is a thickness unevenness, as shown in the first light-emitting layer 501 in Figure 5, the current concentrates in the left half of the light-emitting layer, causing an uneven distribution of light emission within the pixel, thus reducing the luminous efficiency. Furthermore, the localized current concentration reduces the device's lifespan.

[0023] To address this problem, the inventors investigated a method in which a second liquid composition is applied to the second pixel region 102, and then the first and second pixel regions of the substrate 100 are exposed to the vapor of a solvent capable of dissolving both the first and second light-emitting materials. As a result, they found that the non-uniformity of the thickness of the first light-emitting layer formed in the first pixel region 101 can be suppressed. The mechanism is explained in Figure 7. As shown in Figure 7(a), after applying the first liquid composition, the second liquid composition is applied after a first drying step. Then, as shown in Figure 7(b), by exposing the first and second pixel regions to the vapor of the solvent, the entire dried first liquid composition formed in the first pixel region 101 is redissolved and becomes fluid, thereby suppressing the non-uniformity of the shape of the first light-emitting layer. Subsequently, by going through a second drying step in which the first and second liquid compositions are dried after exposure to solvent vapor, the problem of defects in the shape of the light-emitting layer formed in the first pixel region 101 and the second pixel region 102 can be solved, as shown in Figure 7(c).

[0024] <Organic light-emitting element> An example of an organic light-emitting element is one having a structure in which an insulating layer, a first electrode, an organic compound layer, and a second electrode are laminated on a substrate in this order. 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 provided between the protective layer and the color filter. One of the first electrode and the second electrode is the anode and the other is the cathode.

[0025] (substrate) The substrate can be made of quartz, glass, silicon, resin, or metal. Alternatively, switching elements such as transistors and wiring may be placed on the substrate, and an insulating layer may be provided on top of them. The insulating layer can be made of any material that allows for the formation of contact holes to ensure conductivity between the anode and the wiring, and provides insulation from wiring that should not be connected. Specific examples of insulating layers include those made of resins such as polyimide, silicon oxide, and silicon compounds such as silicon nitride. As for the substrate manufacturing method, methods such as those disclosed in Japanese Patent Publication No. 2008-46306 can be used. As shown in Figure 1, the substrate has a first pixel region 101 to which a first liquid composition containing a first light-emitting material is applied, and a second pixel region 102 to which a second liquid composition containing a second light-emitting material is applied. Furthermore, to prevent mixing of liquid compositions between adjacent pixel regions, the pixel regions are surrounded by partitions 103 provided on the substrate. Furthermore, it is preferable that the upper surface of the partition wall 103 is hydrophobic, having low affinity for the liquid components in the liquid composition, while the bottom surfaces of the pixel regions 101 and 102 are hydrophilic, having high affinity for the liquid components in the liquid composition. By making the bottom surfaces of the pixel regions hydrophilic, the interaction between the liquid composition and the bottom surfaces of the pixel regions is strengthened, allowing the liquid composition to be held more stably even when it overflows from the pixel regions. Also, by making the upper surface of the partition wall 103 hydrophobic and the bottom surfaces of the pixel regions 101 and 102 hydrophilic, when evaporation of the liquid components of the liquid composition applied to the pixel regions progresses, the liquid composition can be drawn into the pixel regions without remaining on the upper surface of the partition wall.

[0026] (electrode) An organic light-emitting element is provided with a pair of electrodes. These electrodes are the anode and the cathode. When a voltage is applied in the direction of light emission, the electrode with the higher potential becomes the anode, and the other becomes the cathode. Alternatively, the electrode supplying holes to the light-emitting layer can be considered the anode, and the electrode supplying electrons can be considered the cathode.

[0027] Materials with a high work function are preferred for the anode. Examples include metals such as gold, platinum, silver, copper, nickel, palladium, cobalt, selenium, vanadium, and tungsten. Other examples include metal oxides such as tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), and indium zinc oxide, as well as mixtures and alloys of metals and metal oxides. Furthermore, conductive polymers such as polyaniline, polypyrrole, and polythiophene are also examples. The electrode may be composed of one or more materials. The anode may also be composed of one or more layers.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] (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.

[0032] (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.

[0033] (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.

[0034] (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.

[0035] (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.

[0036] 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.

[0037] At least one of the organic compound layers of the organic light-emitting device contains an organometallic complex. Specifically, the organometallic complex is preferably contained in at least one layer such as a hole implantation layer, a hole transport layer, an electron blocking layer, an emissive layer, a hole-exciton blocking layer, an electron transport layer, or an electron implantation layer. In particular, it is preferable that it be contained in the emissive layer.

[0038] (First liquid composition and second liquid composition) The liquid application device described later applies a liquid composition containing a light-emitting material to a pixel region provided on a substrate. The pixel region is a region surrounded by partitions. The liquid composition dissolves the light-emitting material in its liquid components and is used to form the aforementioned light-emitting layer. 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 the desired function to the organic compound layer and to be compatible with the film-forming process.

[0039] Examples of luminescent materials include luminescent organic compounds. Examples of luminescent organic compounds include phosphorescent materials and fluorescent materials. The luminescent organic compound may be either a low molecular weight material or a high molecular weight material, or a mixture thereof. In addition to the luminescent organic compound, the luminescent layer may also contain an organic compound (I) different from 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. 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.

[0040] When the light-emitting layer contains a luminescent organic compound and organic compound (I), the luminescent organic compound is the dopant of the light-emitting layer, and organic compound (I) is the host of the light-emitting layer. Furthermore, when the light-emitting layer contains organic compound (II) in addition to the luminescent organic compound and organic compound (I), organic compound (II) is the assisting material.

[0041] 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.

[0042] Therefore, in this invention, the term "luminescent material" collectively refers to the dopant, host, and assist material. The luminescent material contained in the liquid composition may be one type or a mixture of multiple types. Furthermore, it is preferable that the first luminescent material contained in the first liquid composition is a luminescent material that emits light of a different color than the second luminescent material contained in the second liquid composition.

[0043] Furthermore, the liquid components included in the liquid composition are not particularly limited as long as they can dissolve the luminescent material. These liquid components (solvent components) preferably have a boiling point of 70°C to 300°C at 1 atmosphere. Examples of liquid 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 liquid components may be a single liquid component or a mixture of multiple liquids. The content (mass%) of the liquid components in the liquid composition is preferably 10.0 times or more and 1000.0 times or less by mass ratio to the content (mass%) of the luminescent material constituting a single luminescent layer.

[0044] The surface tension of a liquid composition can be adjusted by appropriately determining the type and content of the solvent component. At 25°C, the surface tension of the liquid composition is preferably 15 mN / m to 75 mN / m, and more preferably 25 mN / m to 45 mN / m. The surface tension of the liquid composition refers to the "static surface tension" measured by the plate method. The surface tension of a liquid composition 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).

[0045] Furthermore, the viscosity of the liquid composition at 25°C is preferably 0.1 mPa·s to 20.0 mPa·s, and more preferably 0.5 mPa·s to 10.0 mPa·s. By keeping the viscosity within the above range, clogging and ejection failures in the liquid ejection head when ejecting using an inkjet method can be suppressed.

[0046] The concentration of the first light-emitting material in the first liquid composition is preferably 10% by mass or less, and more preferably 6% by mass or less, based on the total mass of the first liquid composition. Similarly, the concentration of the second light-emitting material in the second liquid composition is preferably 10% by mass or less, and more preferably 6% by mass or less, based on the total mass of the second liquid composition. When the concentration of the light-emitting material is 10% by mass or less, the amount of light-emitting material deposited near the discharge port is small, and the concentration of the light-emitting material in the liquid composition discharged later is also low. Therefore, even if the light-emitting material precipitates near the discharge port, it can be quickly redissolved and removed from the vicinity of the discharge port. This suppresses the inhibition of liquid composition application by precipitates and stabilizes discharge performance. Furthermore, the concentration of the light-emitting material in the liquid composition is preferably 1% by mass or more, and more preferably 2% by mass or more. When the concentration of the light-emitting material is 1% by mass or more, there is no need to increase the amount of liquid composition applied to the pixel area more than necessary, and color mixing can be further suppressed.

[0047] <Method for manufacturing organic light-emitting elements, and apparatus for manufacturing organic light-emitting elements> The following describes the method for manufacturing an organic light-emitting element and the apparatus for manufacturing an organic light-emitting element according to the present invention.

[0048] (First liquid application step and first liquid application means) In the first liquid application step, a first liquid composition containing a first light-emitting material is applied to a first pixel region surrounded by a partition on the substrate. If the first pixel regions constitute a group of first pixel regions arranged in a row adjacent to each other on the substrate, the first liquid composition is applied to each first pixel region. Here, the volume of the first liquid composition applied to the first pixel region in the first liquid application step is made to be greater than the volume of the first pixel region. This is to reduce variations in the thickness of the first light-emitting layer between pixel regions. Furthermore, it is preferable that the volume of the first liquid composition be five times or more the volume of the first pixel region, as this can further reduce variations in the thickness of the formed light-emitting layer. There is no particular upper limit to the volume of the first liquid composition as long as it does not encroach on the second pixel region adjacent to the first pixel region, but it is preferable that it be 12 times or less the volume of the first pixel region.

[0049] The first liquid application means is a liquid application device that applies a first liquid composition containing a first light-emitting material to a first pixel region surrounded by a partition on a substrate. This liquid application device only needs to be able to apply the liquid composition to the pixel region, and can use a dispenser or an inkjet-type liquid ejection device. In particular, an inkjet-type liquid ejection device that can apply the liquid composition in droplet form is preferred from the viewpoint of droplet application accuracy and controllability of droplet application volume.

[0050] <First drying step and first drying means> In the first drying step, the first pixel region is dried after the first liquid application step. This prevents mixing of the first and second liquid compositions on the substrate, even if the liquid components in the first liquid composition applied to the first pixel region evaporate and the second liquid composition applied in the second liquid application step described later is applied. The first drying step allows the first liquid composition that overflows from the first pixel region onto the upper surface of the partition wall placed on the substrate to be contained within the first pixel region and moved away from the upper surface of the partition wall; it is not necessary to completely remove the liquid components contained in the first liquid composition. Examples of drying in the first drying step include vacuum drying, heat drying, and natural drying. Furthermore, in the vapor exposure step described later, it is necessary to redissolve the film formed by drying the first liquid composition. Therefore, from the viewpoint of efficiently redissolving the film containing the first liquid composition, it is preferable that the state of the dried first liquid composition after the first drying step is a wet state in which the liquid components have not been completely removed. The wet state of the film formed by the dried first liquid composition can be determined, for example, by the following method. After applying the first liquid composition, observing the drying process with a camera or the like allows observation of the decrease in the liquid level of the first liquid composition applied to the first pixel region due to the evaporation of the liquid components. As the liquid components evaporate, the liquid level becomes lower than the upper surface of the partition wall, and eventually, the liquid components are removed and the solid components in the first liquid composition are fixed as a film. For example, let T1 be the time from the application of the first liquid composition until the liquid level becomes lower than the upper surface of the partition wall, and T2 be the time from the application of the first liquid composition until the film formed by the first liquid composition is fixed. In this case, if the second liquid composition is applied between T1 and T2 after the application of the first liquid composition, the first liquid composition can be moved away from the upper surface of the partition wall, and the second liquid composition can be applied in a wet state. Here, in order for the first liquid composition to smoothly move away from the upper surface of the partition wall, it is preferable that the upper surface of the partition wall has liquid-repellent properties with respect to the first liquid composition.

[0051] The first drying means is a drying apparatus that dries the first image region after the first liquid composition has been applied by the first liquid application means. This drying apparatus can be a drying apparatus capable of accelerating drying, such as a vacuum drying apparatus or a heating drying apparatus. However, when a drying apparatus is used, the drying speed is fast, which can make it difficult to control the wet state of the first liquid composition after drying. Therefore, it is preferable to use natural drying, which does not apply external energy, for the drying in the first drying step. Furthermore, by performing the first drying step by natural drying, there is no need to provide a vacuum apparatus or heating apparatus as a drying means, which is an advantage as it can suppress the complexity of the manufacturing process in the manufacturing method of organic light-emitting devices.

[0052] (Second liquid application process and second liquid application apparatus) In the second liquid application step, after the first drying step, a second liquid composition containing a second light-emitting material different from the first light-emitting material is applied to a second pixel region adjacent to the first pixel region and surrounded by a partition on the substrate. If the second pixel regions constitute a group of second pixel regions arranged in a row adjacent to each other on the substrate, the second liquid composition is applied to each second pixel region. Here, similar to the first liquid application step, the volume of the second liquid composition applied to the second pixel region in the second liquid application step is made larger than the volume of the second pixel region. Similar to the first liquid application step, this reduces variations in the thickness of the second light-emitting layer between pixel regions. Furthermore, it is preferable that the volume of the second liquid composition be five times or more the volume of the second pixel region, as this further reduces variations in the thickness of the formed light-emitting layer. There is no particular upper limit to the volume of the second liquid composition applied, as long as it does not enter the second pixel region adjacent to the first pixel region, but it is preferable that it be 12 times or less the volume of the second pixel region. Furthermore, it is preferable that the second liquid application step is performed in a wet state in which liquid components remain in the first liquid composition after drying in the first pixel region.

[0053] The second liquid application means is a liquid application device that, after drying by the first drying means, applies a second liquid composition containing a second light-emitting material different from the first light-emitting material to a second pixel region adjacent to the first pixel region and surrounded by a partition on the substrate. The same liquid application device as the first liquid application means can be used for this second liquid application device.

[0054] <Steam exposure process and steam exposure means> In the vapor exposure step, after the second liquid application step, the first and second pixel regions are exposed to vapor of a solvent capable of dissolving both the first and second light-emitting materials. This allows the first liquid composition, which was dried in the first drying step, to be redissolved. Therefore, the solvent must be capable of dissolving the first light-emitting material contained in the first liquid composition. Furthermore, the solvent is exposed as vapor, not liquid. If the solvent is exposed in liquid form, the first and second liquid compositions, which were dried in the first drying step, may mix through the liquid solvent. Therefore, the solvent used in the vapor exposure step is preferably a solvent that evaporates easily, and is particularly preferably a solvent with a boiling point of 200°C or lower. It is also preferable that the boiling point of the solvent used in the vapor exposure step be 100°C or higher. The reason for this is as follows. After the vapor exposure step, a second drying step is performed, in which the solvent used in the solvent vapor exposure step is removed by drying. The second drying step is preferably performed by vacuum drying, and after the vapor exposure step, the material is transferred to a chamber capable of vacuum drying. If the boiling point of the solvent used in the vapor exposure process is below 100°C, drying may progress during transfer to the chamber, potentially complicating the manufacturing process.

[0055] Solvents used in the vapor exposure process include, for example, methylcyclohexanone (boiling point: 101°C), toluene (boiling point: 111°C), 1,2-dimethylcyclohexanone (boiling point: 124°C), chlorobenzene (boiling point: 132°C), m-xylene (boiling point: 139°C), 3-fluoro-O-xylene (boiling point: 150°C), anisole (boiling point: 155°C), 1,3,5-trimethylbenzene (boiling point: 165°C), and 1,2,4-trimethyl Examples of suitable solvents include toluene (boiling point: 169°C), dimethyl sulfoxide (boiling point: 189°C), O-tolunitrile (boiling point: 205°C), cyclohexylbenzene (boiling point: 236°C), diphenyl ether (boiling point: 259°C), 2-phenoxytoluene (boiling point: 265°C), 3-phenylpyridine (boiling point: 272°C), 2-phenylanisole (boiling point: 274°C), and 1,4-dimethylbenzene (boiling point: 280°C). Among these, toluene is particularly preferred from the viewpoint of high solubility of the light-emitting material and its ease of vaporization. In the vapor exposure step, it is preferable to expose the pixel area to solvent vapor for 2 minutes or more from the viewpoint of sufficiently redissolving the dried first liquid composition and giving it fluidity. Furthermore, from the viewpoint of productivity, it is preferable to limit the exposure time of the pixel area to solvent vapor to 5 minutes or less.

[0056] The vapor exposure means is a vapor exposure device that, after the application of the second liquid composition by the second liquid application means, exposes the first and second pixel regions to vapor of a solvent capable of dissolving both the first and second light-emitting materials. The vapor exposure device is not particularly limited as long as it is capable of exposing the first and second pixel regions to vapor of a solvent capable of dissolving both the first and second light-emitting materials; known devices can be used.

[0057] <Second drying process and second drying apparatus> In the second drying step, after the vapor exposure step, the first and second pixel regions are dried to form a first light-emitting layer containing a first light-emitting material in the first pixel region and a second light-emitting layer containing a second light-emitting material in the second image region. Examples of drying methods in the second drying step include vacuum drying, heat drying, and natural drying. The first liquid composition has gone through the first drying step after the first liquid application step, while the second liquid composition may not have been dried after the second liquid application step and before the vapor exposure step. Therefore, the amount of liquid components contained in the first and second liquid compositions may differ, which may result in a time difference in the formation of the light-emitting layers in the second drying step. For example, if, immediately before the second drying step, the amount of liquid components in the second liquid composition is greater than the amount of liquid components in the first liquid composition, the first light-emitting layer will be formed from the first liquid composition before the second light-emitting layer is formed from the second liquid composition. In other words, at the time the first light-emitting layer is formed, there may be liquid components remaining in the dried second liquid composition. At this time, the liquid components of the second liquid composition turn into vapor, suppressing the drying of the adjacent first liquid composition, and the shape of the light-emitting layer may be disturbed by the mechanism described above. Therefore, in the second drying step, it is preferable to minimize the time difference between the formation of the first light-emitting layer by the first liquid composition and the formation of the second light-emitting layer by the second liquid composition. For this reason, the drying in the second drying step is preferably vacuum drying or heating drying, which can remove the liquid components in a short time. Vacuum drying is particularly preferable because it can quickly discharge the vapor of the liquid components generated from the liquid composition to the outside of the system (outside the organic light-emitting element manufacturing apparatus). Vacuum drying and heating drying can be used consecutively or in combination.

[0058] The second drying means is a drying apparatus that, after steam exposure by the steam exposure means, dries the first and second pixel regions to form a first light-emitting layer containing a first light-emitting material in the first pixel region and a second light-emitting layer containing a second light-emitting material in the second image region. The same drying apparatus as the first drying means can be used for this drying apparatus. The drying apparatus used as the second drying means is preferably a vacuum drying apparatus or a heating drying apparatus because it can remove liquid components from the liquid composition in a short time. A vacuum drying apparatus is particularly preferable because it can quickly discharge the steam generated from the liquid composition outside the system (outside the organic light-emitting device manufacturing apparatus).

[0059] <Third drying step and third drying means> The method for manufacturing an organic light-emitting element preferably includes a third drying step after the second liquid application step and before the vapor exposure step. In the third drying step, the area within the second pixel region is dried after the second liquid application step. As a result, the amount of liquid components in both the first and second liquid compositions is reduced before the vapor exposure step. Therefore, even if the first and second liquid compositions dried by the vapor exposure step are redissolved, the amount of liquid components in the redissolved first and second liquid compositions will be approximately the same. Furthermore, in the second drying step, the time difference between the formation of the first light-emitting layer by the first liquid composition and the formation of the second light-emitting layer by the second liquid composition can be reduced. Examples of drying in the third drying step include vacuum drying, heating drying, and natural drying. For the drying in the third drying step, vacuum drying or heating drying, which can remove liquid components in a short time, is preferred. Vacuum drying is particularly preferred because it can quickly discharge the vapor of liquid components generated from the liquid composition to the outside of the system (outside the organic light-emitting element manufacturing apparatus).

[0060] The third drying means is a drying apparatus that dries the area within the second pixel region after the application of the second liquid composition by the second liquid application means. The same type of drying apparatus as that used for the first drying means can be used for this third drying means. The drying apparatus used for the third drying means is preferably a vacuum drying apparatus or a heating drying apparatus, as it can remove liquid components from the liquid composition in a short time. [Examples]

[0061] 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.

[0062] In these examples and comparative examples, an example using an inkjet as the liquid composition dispensing device is described, but the present invention is not limited thereto. Furthermore, the liquid composition will be referred to as "ink" in these examples.

[0063] <Preparation of ink (liquid composition) for forming the luminescent layer> (Red luminescent ink) Red luminescent material inks R1 to R4, which are first luminescent layer forming inks (first liquid compositions) capable of forming a red luminescent layer, were prepared by mixing 3,3'-di(9H-carbazole-9-yl)-1,1'-biphenyl (hereinafter referred to as m-CBP), a carbazole-based luminescent material, and bis(2-phenylpyridine)(acetylacetonato)iridium(III) (hereinafter referred to as (ppy)2Ir(acac)), an iridium complex, as the first luminescent material, in the proportions (unit: mass%) shown in Table 1, as the first luminescent material, as the solute, and then dissolving it in the solvent anisole, followed by pressure filtration using a pore size 0.2 μm filter. The solute concentration of inks R1 to R4 is obtained by dividing the total amount of m-CBP and (ppy)2Ir(acac) by the total amount of ink.

[0064] [Table 1]

[0065] (Green luminescent ink) As shown in Table 1, a carbazole-based luminescent material, m-CBP, and an iridium complex, bis(2-(2-benzo4,5-achienylpyridinate-N,C3)iridium acetylacetate (hereinafter referred to as (btp)2Ir(acac)), were mixed in the proportions (unit: mass%) shown in Table 1 to obtain green luminescent material inks G1 to G4, which are second liquid compositions for forming a green luminescent layer. These were prepared by mixing the carbazole-based luminescent material m-CBP and the iridium complex bis(2-(2-benzo4,5-achienylpyridinate-N,C3)) as a solute, dissolving it in anisole as a solvent, and then pressure filtering it using a filter with a pore size of 0.2 μm to form a green luminescent layer. The solute concentration of inks G1 to G4 is obtained by dividing the total amount of m-CBP and (btp)2Ir(acac) by the total amount of ink.

[0066] [Table 2]

[0067] <Ink dispensing device (liquid dispensing device)> A modified version of a material printer (product name "DMP-2831," manufactured by Fujifilm), which is a liquid ejection device with an inkjet-type liquid ejection head, was used as the ink dispensing device. In the modified device, the flow path and ink tank within the inkjet-type liquid ejection head were modified so that multiple inks could be ejected from the same liquid ejection head. One million drops of ink were ejected from each ejection port, and the total weight of the ejected ink was measured. The total ejected volume was calculated by dividing the weight by the ink density of the ejected ink, and the average volume of one droplet ejected from one ejection port was calculated. The average volume per droplet was 3 pL.

[0068] <Preparation of substrates for organic light-emitting diodes> A substrate 100, as shown in Figure 1, was prepared with reference to Japanese Patent Publication No. 2008-46306. The substrate 100 is a substrate on which multiple first pixel regions 101 and second pixel regions 102 are formed, surrounded by partition walls 103. As shown in Figure 1, the first pixel regions 101 and second pixel regions 102 are elongated in the X-axis direction, shorter in the Y-axis direction, and have rounded corners. The first pixel regions and second pixel regions 102 were formed with a length of 80 μm in the longitudinal direction (X-axis direction), a length of 26 μm in the transverse direction (Y-axis direction), and a depth of 1.5 μm in the Z-axis direction. The volume of both the first and second pixel regions was 3 pL. In addition, multiple first pixel regions were formed at equal intervals of 20 μm in the X-axis direction, constituting a first pixel region group 401. Similarly, multiple second pixel regions are formed at equal intervals of 20 μm in the X-axis direction, constituting the second pixel region group 402. In addition, adjacent first and second pixel regions are formed alternately at equal intervals of 10 μm in the Y-axis direction.

[0069] <Rating> The aforementioned substrate and the first ink (red light-emitting material ink) and second ink (green light-emitting material ink) of the types shown in Table 3 were set in the ink application device. Then, as shown in Figure 4, the first ink was applied to the first pixel region group 401 adjacent in the X-axis direction, and then drying was performed using the first drying step and first drying time (seconds) shown in Table 3. Note that the first drying step was not performed in Comparative Examples 1 to 3. "Reduced pressure drying" in the "First drying step" column of Table 3 means that the atmosphere around the first pixel region group 401 was reduced to 1 kPa within 10 seconds at room temperature, and then the pressure was maintained for 30 seconds. "Natural drying" means that the material was left to air dry naturally for 120 seconds.

[0070] Subsequently, the second ink was applied to the second pixel region group 401 and the adjacent pixel region group 402 in the Y-axis direction. Before applying the second ink, the state of the first pixel region group 401 was observed using a camera mounted on the inkjet head, and the state of the first ink applied to the pixel region group 401 was classified as "dry," "wet," and "liquid," respectively, and recorded in the "First Ink State" column of Table 3. Here, "dry," "wet," and "liquid" in "First Ink State" refer to the following states, respectively.

[0071] • Drying: The liquid level of the first ink is lower than the upper surface of the partition surrounding the first pixel region, the decrease in the liquid level of the first ink stops, and the film is fixed. • Wet: The liquid level of the first ink is lower than the top surface of the partition surrounding the first pixel area, and the decrease in the liquid level of the first ink has not stopped. • Liquid state: A state in which the liquid level of the first ink is above the upper surface of the partition wall surrounding the first pixel area.

[0072] After applying the second ink, the first pixel region group 401 and the second pixel region group 402 were exposed for 120 seconds under the vapor of the solvent listed in the "Solvent for Vapor Exposure" column of Table 3. Here, the "Solubility of the Luminescent Material in Vapor" column indicates whether or not the luminescent material contained in the first liquid composition dissolves in the vapor of the solvent for vapor exposure. Specifically, the solubility of this luminescent material in the solvent vapor was confirmed by the following method.

[0073] The luminescent material contained in the first liquid composition was added dropwise to the solvent and stirred at room temperature for 2 hours using a magnetic stirrer. The presence or absence of undissolved luminescent material after stirring was then observed. For example, if 20 mg of luminescent material was added dropwise to 980 mg of solvent and stirred, the solubility was judged to be 2% by mass or more if there was no undissolved material, and less than 2% by mass if there was undissolved material. In the "Solubility of Luminescent Material in Vapor" column of Table 3, solvents marked "A" had a solubility of 2% by mass or more of the luminescent material. Solvents marked "C" had a solubility of less than 2% by mass of the luminescent material.

[0074] After steam exposure, a second drying process was performed using the method shown in Table 3 to form a first light-emitting layer containing the first light-emitting material and a second light-emitting layer containing the second light-emitting material. In the "Second Drying Process" column of Table 3, "Reduced Pressure Drying" means that the atmosphere surrounding the first pixel region group 401 and the second pixel region group 402 was reduced to 1 kPa within 10 seconds at room temperature, and then the pressure was maintained for 30 seconds. "Natural Drying" means that the samples were left to air dry naturally for 120 seconds.

[0075] The amount of first ink applied to the first pixel area group 401 and the amount of second ink applied to the second pixel area group 402 are recorded in the "Ink Application Amount / Pixel Area Volume" column. The value shown here is the total amount (volume) of ink applied to one pixel area divided by the volume per pixel area, indicating how many times the amount of ink applied to a pixel area is compared to the volume of the pixel area. In the inkjet liquid ejection head used in this example and comparative example, the average volume per droplet was 3 pL, and the volume of the pixel area was also 3 pL. Therefore, for example, in Example 1, 5 droplets were applied to one pixel area, and in Example 7, 12 droplets were applied.

[0076] In this embodiment, "A" and "B" were defined as acceptable levels, and "C" as an unacceptable level, according to the evaluation criteria for each item below. The evaluation results are shown in Table 4. It was also confirmed that the organic light-emitting element formed by the method of Example 1 functions as a light-emitting element.

[0077] [Table 3]

[0078] [Table 4]

[0079] (mixed colors) After applying the second ink and before exposure to vapor, the presence or absence of color mixing between the first and second inks was evaluated. The evaluation was performed visually using a camera mounted on the inkjet head. In Table 4, no color mixing was observed in the examples and comparative examples labeled "A," but in the comparative example labeled "C," contact and color mixing between the first and second inks were observed.

[0080] (Variation in the thickness of the light-emitting layer between pixel regions) After the second drying process was completed, the thickness of the light-emitting layer formed in the first pixel region was measured, and the variation in the thickness of the light-emitting layer between pixel regions was evaluated. The thickness of the light-emitting layer was measured using a stylus profiler (product name "Alpha-Step D-500", manufactured by KLA-Tencor). For the light-emitting layer formed in one pixel region, the center of the light-emitting layer in the X-axis direction was measured in the Y-axis direction in Figure 4. 100 pixel regions were randomly selected from the first pixel region group 401, and the thickness of the first light-emitting layer was measured. Then, the average thickness of each first light-emitting layer was summed and divided by 100 to calculate the coefficient of variation from the mean and standard deviation, and the variation in the thickness of the first light-emitting layer was evaluated according to the evaluation criteria shown below. The coefficient of variation was calculated from "standard deviation / mean". A: The coefficient of variation was 0.10 or less. B: The coefficient of variation was greater than 0.10 and less than or equal to 0.15. C: The coefficient of variation exceeded 0.15.

[0081] (Shape of the light-emitting layer within the pixel area) After the second drying process was completed, the shape of the light-emitting layer within the pixel region was evaluated. The shape of the light-emitting layer was measured using a stylus profiler (product name "Alpha-Step D-500", manufactured by KLA-Tencor), similar to the evaluation of the variation in the thickness of the light-emitting layer. One pixel region was randomly selected from the first pixel region group 401, and the center of the first light-emitting layer in the X-axis direction was measured in the Y-axis direction in Figure 4.

[0082] Figures 5 and 6 show examples of shape measurements of the first light-emitting layer formed within a single pixel region. The region of the measured first light-emitting layer was divided at its center in the Y-axis direction, with the upstream region in the Y-axis direction designated as the first region and the downstream region in the Y-axis direction designated as the second region. The average thickness of the first region and the average thickness of the second region were calculated. Furthermore, the ratio of the average thickness of the first region to the average thickness of the second region was calculated, and the shape of the light-emitting layer was evaluated according to the evaluation criteria shown below. Note that the closer the ratio of the average thickness of the first region to the average thickness of the second region is to 1.0, the higher the uniformity of the shape of the light-emitting layer was evaluated. A: The ratio of the average thickness of the first region to the average thickness of the second region was between 1.0 and 1.5. B: The ratio of the average thickness of the first region to the average thickness of the second region was greater than 1.5 and less than or equal to 2.0. C: The value of the average thickness of the first region divided by the average thickness of the second region exceeded 2.0.

[0083] (Dischargeability) The inkjet-type liquid ejection head mounted on the ink application device was continuously ejected for 10 minutes, then ejection was stopped for 2 hours, and then ejection was resumed. Using the position where the ink droplets adhered to the substrate before ejection was stopped as a reference, the number of ink droplets ejected after ejection resumed was measured until the displacement of the ink droplets to the substrate position was 5 μm or less compared to the position before ejection was stopped. The number of ejected droplets was classified according to the evaluation criteria shown below, and the ejection performance was evaluated. A: The number of rounds dispensed was less than 100. B: The number of rounds dispensed exceeded 100. [Explanation of Symbols]

[0084] 100 circuit boards 101 First pixel region 102 Second pixel region 103 Bulkhead 201 First liquid composition 202 Second liquid composition

Claims

1. A first liquid application step involves applying a first liquid composition containing a first light-emitting material to a first pixel region surrounded by a partition on a substrate, Following the first liquid application step, a first drying step is performed to dry the first pixel region, A second liquid application step is performed after the first drying step, in which a second liquid composition containing a second light-emitting material different from the first light-emitting material is applied to a second pixel region adjacent to the first pixel region and surrounded by a partition on the substrate. Following the second liquid application step, a vapor exposure step is performed in which the first pixel region and the second pixel region are exposed to a vapor of a solvent capable of dissolving both the first and second light-emitting materials. A method for manufacturing an organic light-emitting element, comprising: a second drying step after the steam exposure step, in which the first pixel region and the second pixel region are dried to form a first light-emitting layer containing the first light-emitting material in the first pixel region and a second light-emitting layer containing the second light-emitting material in the second image region, respectively, In the first liquid application step, the volume of the first liquid composition applied to the first pixel region is greater than the volume of the first pixel region. A method for manufacturing an organic light-emitting element, characterized in that the volume of the second liquid composition applied to the second pixel region in the second liquid application step is greater than the volume of the second pixel region.

2. The method for manufacturing an organic light-emitting element according to claim 1, characterized in that the second drying step is carried out by reduced-pressure drying.

3. The method for manufacturing an organic light-emitting element according to claim 1, characterized in that the second liquid application step is performed in a wet state in which liquid components remain in the first liquid composition after drying in the first pixel region.

4. The method for producing an organic light-emitting element according to claim 1, characterized in that the boiling point of the solvent is 200°C or lower.

5. The method for manufacturing an organic light-emitting element according to claim 1, characterized in that the concentration of the first light-emitting material in the first liquid composition is 6% by mass or less based on the total mass of the first liquid composition, and the concentration of the second light-emitting material in the second liquid composition is 6% by mass or less based on the total mass of the second liquid composition.

6. In the first liquid application step, the volume of the first liquid composition applied to the first pixel region is five times or more the volume of the first pixel region. The method for manufacturing an organic light-emitting element according to claim 1, characterized in that, in the second liquid application step, the volume of the second liquid composition applied to the second pixel region is five times or more the volume of the second pixel region.

7. A first liquid application means for applying a first liquid composition containing a first light-emitting material to a first pixel region surrounded by a partition on a substrate, After the application of the first liquid composition by the first liquid application means, a first drying means for drying the first image region, A second liquid application means applies a second liquid composition containing a second light-emitting material different from the first light-emitting material to a second pixel region adjacent to the first pixel region and surrounded by a partition on the substrate, after drying by the first drying means. After the application of the second liquid composition by the second liquid application means, a vapor exposure means is provided to expose the first pixel region and the second pixel region to a vapor of a solvent capable of dissolving both the first and second light-emitting materials. An apparatus for manufacturing an organic light-emitting element, comprising: a second drying means for drying the first pixel region and the second pixel region after steam exposure by the steam exposure means, thereby forming a first light-emitting layer containing the first light-emitting material in the first pixel region and a second light-emitting layer containing the second light-emitting material in the second image region, respectively, The volume of the first liquid composition applied to the first pixel region by the first liquid application means is greater than the volume of the first pixel region. An apparatus for manufacturing an organic light-emitting element, characterized in that the volume of the second liquid composition applied to the second pixel region by the second liquid application means is greater than the volume of the second region.

Images