JP2004253179A - Method and apparatus for manufacturing functional element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a functional element such as an EL element, a color filter, or a color changing filter, where the method can form the functional element having a thickness difference between the center and the periphery of a functional layer such as an organic EL layer, a coloring layer, or a color changing layer, and the thickness difference is in the order not to cause any disadvantage such as color tone uneveness; and to provide an apparatus used for manufacturing the functional element. <P>SOLUTION: The method for manufacturing the functional element having a substrate and the functional layer formed in the shape of a pattern on the substrate by a discharge method comprises a coating step for applying a coating liquid for functional layer formation in the shape of the pattern on the substrate by the discharge method where the coating liquid includes a solvent and forms the functional layer, and a rapid solidifying step for solidifying the coating liquid for functional layer formation before volatilization of the solvent. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a functional element such as an organic electroluminescence (hereinafter, EL may be abbreviated as EL) element, a color filter or a color conversion filter, and an apparatus for manufacturing the same.
[0002]
[Prior art]
2. Description of the Related Art In recent years, flat display devices (flat displays) have been used in many fields and places, and have become increasingly important as computerization has progressed. At present, a typical flat display is a liquid crystal display (LCD). However, as a flat display based on a display principle different from the LCD, an organic EL, an inorganic EL, a plasma display panel (PDP), and a light emitting diode display device are used. (LED), a fluorescent display device (VFD), a field emission display (FED), and the like are also being actively developed. Each of these new flat displays is called a self-luminous type, and differs greatly from LCDs in the following points and has excellent features not found in LCDs.
[0003]
The LCD is called a light receiving type, and the liquid crystal does not emit light by itself, but operates as a so-called shutter that transmits and blocks external light, thereby constituting a display device. This requires a light source and generally requires a backlight. On the other hand, the self-luminous type emits light by itself, so that a separate light source is unnecessary. In a light-receiving type such as an LCD, the backlight is always turned on regardless of the mode of display information, and power that is almost the same as in the full display state is consumed. On the other hand, the self-luminous type has an advantage that it consumes less power compared to the light-receiving display device in principle, because only the portions that need to be lit consume power in accordance with display information. .
[0004]
Further, in LCDs, it is difficult to completely eliminate light leakage even if the amount is small, because the light from the backlight light source is shielded from light to obtain a dark state. Therefore, an ideal dark state can be easily obtained, and the self-luminous type is overwhelmingly superior in contrast.
[0005]
In addition, since the LCD uses polarization control by birefringence of liquid crystal, the display state changes greatly depending on the viewing direction, that is, the LCD has a strong dependence on the viewing angle. However, the self-luminous type has almost no problem.
[0006]
Further, since the LCD utilizes an orientation change caused by the dielectric anisotropy of the liquid crystal which is an organic elastic substance, a response time to an electric signal is 1 ms or more in principle. On the other hand, the above-mentioned technology, which is being developed, utilizes so-called carrier transition such as electrons / holes, electron emission, plasma discharge, and the like, so that the response time is in the order of ns. It is so fast that there is no problem of moving image afterimage caused by the slow response of the LCD.
[0007]
Among self-luminous display devices having such advantages, research on organic EL is particularly active. The organic EL is also called OEL (Organic EL) or Organic Light Emitting Diode (OLED).
[0008]
The organic EL element has a structure in which a layer containing an organic compound (EL layer) is sandwiched between a pair of electrodes of an anode and a cathode, and is composed of “anode electrode / hole injection layer / light emitting layer / cathode electrode” such as tan. It is based on a laminated structure (see Patent Document 1).
Henry uses a high-molecular material, while Tan uses a low-molecular material (see Patent Document 2).
Further, the efficiency is improved by using a hole injection layer or an electron injection layer, or the emission color is controlled by doping a light emitting layer with a fluorescent dye or the like.
[0009]
As a method for manufacturing a display device using an organic EL, a light-emitting material is discharged to form a light-emitting layer using an ink-jet discharge device (for example, Patent Documents 3 and 4). , Patent Documents 5 and 6).
In Patent Document 3, in a solution of a luminescent material, after discharging onto a substrate, the solvent is removed at room temperature, and then the substrate is heated or dried by vacuum heating. However, there is no effect of making the film thickness uniform by forced drying.
[0010]
Further, in a method of manufacturing an organic EL display device by a similar discharge method, when the light emitting layer in an ink solution state is formed into a film, some of the methods of forcibly evaporating and drying the solvent have already been performed. For example, Patent Literature 4 discloses a technique in which a light-emitting material that is made into an ink is supplied onto a base material by using a solvent having a high boiling point, and the base material is heat-treated. This aims to obtain the effect of drying by heating the substrate even after forming the entire luminescent layer on the substrate by slowing down the evaporation rate of the solvent by using a high boiling point solvent and increasing the time for natural drying. Things. However, in order to completely remove the high-boiling-point solvent, heat treatment is performed at a higher temperature, so that the problem of deterioration of the light-emitting material is inevitable. This problem has a significant effect particularly on shortening the light emission life even if no deterioration is observed in the initial light emission characteristics. If the heat treatment is not performed at a sufficiently high temperature, the problem of thermal deterioration of the light emitting layer does not occur, but the solvent remains inside the filmed light emitting layer, and the reliability of the light emitting layer is greatly impaired. It will be.
[0011]
Patent Document 5 discloses a technique of forming a light-emitting layer by performing heat treatment at a temperature higher than the softening point of the light-emitting layer material. However, in this case, there is a problem of deterioration of the light-emitting material as described above. .
[0012]
Further, in Patent Document 6, the solvent vapor evaporated from the discharged droplet is forcibly removed from the surface of the base material by spraying a gas at an angle to the base material. This is because the residual state of the solvent vapor on the surface of the base material affects other pixels, in particular, the dry state changes depending on the pixel, because the solvent evaporated from the newly ejected pixel touches the already ejected pixel. Is preventing things. However, it only blows dry solvent vapor and drying is not compulsory. Although there is an effect of improving the uniformity of drying in the substrate surface, the effect of improving the three-dimensional film thickness uniformity within the pixel is not only described but also not recognized as a problem. .
[0013]
Further, in Patent Document 7, similarly to the formation of an organic material including an organic EL, by covering the ink jet head with a shield, drying of the nozzle surface of the head is prevented, clogging is reduced, and stable ejection of the ink material is achieved. However, there is no description for controlling the dry state and the film shape of the ink material discharged to the base material, and it is apparent that such control cannot be performed.
[0014]
A method for manufacturing such a conventional EL element will be described with reference to the drawings. As shown in FIG. 6A, an organic EL layer forming coating liquid 62 for forming an organic EL layer is discharged from a finely processed nozzle 63 onto a base material 61 on which a partition wall 60 is formed. Apply. Due to the surface tension of the coating liquid, the coating liquid 62 for forming the organic EL layer applied between the partition walls 60 becomes convex from the end contacting the partition wall 60 to the central part, as shown in FIG. To form a meniscus surface profile. When the solvent is evaporated and dried and solidified in such a state of the meniscus surface shape, as shown in FIG. 6C, a concave shape is formed from the end contacting the partition wall 60 toward the center, and the center is formed. The organic EL layer 64 has a large difference in film thickness between the end portion and the end portion. If the difference is large, inconvenience may occur due to the difference. For example, when an electric field is applied to such an organic EL layer having a non-uniform film thickness, as shown in FIG. 7, the current concentrates on the central portion 65 of the organic EL layer 64 where the film thickness is small. Since the current hardly flows through the end portion 66 which is in contact with the partition wall 60 and has a large film thickness, a difference occurs in light emission luminance, and a phenomenon occurs in which only the central portion 65 emits light. FIG. 7 shows a case where the pixel opening in which the organic EL layer 64 is formed is rectangular and an oval. If light is emitted only in the central portion of the pixel, sufficient brightness and efficiency cannot be achieved as a display device.
[0015]
Also, the problem of disconnection of the counter electrode is important. Usually, since the counter electrode is formed by vapor deposition of a metal thin film, even if the counter electrode is thicker than 100 nm, the limit is 500 nm. If it is thicker, it is no longer a thin film, and the tension of the metal itself increases the risk of rolling up and peeling. In the film thickness in this range, when the partition has a height of 5 μm or more, the counter electrode 80 formed so as to cover the surfaces of the partition 60 and the organic EL layer 64 as shown in FIG. At 81, disconnection is likely to occur, and many defective pixels in which no electric field is applied to the organic EL layer 64 are generated. The problem of disconnection of the opposing electrode at the corners of the partition can be solved by making the partition into a curved shape as shown in FIG. However, the problem of the non-uniform thickness of the organic EL layer described above is not solved.
[0016]
The problem caused by the unevenness of the film thickness described above is not limited to the organic EL layer of the EL element. As shown in FIG. 10, the coloring layer 101 is formed by using the black matrix 100 as a partition wall by an ejection method such as an inkjet method. The same applies to the case where the color conversion layer of the color conversion filter is formed by an ejection method, although not shown, and a color tone unevenness occurs due to a difference in film thickness between the center portion and the end portion, and high-definition color formation is achieved. This has the effect of reducing the device life.
[0017]
[Patent Document 1]
JP-A-57-51781
[Patent Document 2]
Patent No. 3249971
[Patent Document 3]
JP-A-11-339957
[Patent Document 4]
WO 00/59267 pamphlet
[Patent Document 5]
JP 2001-85161 A
[Patent Document 6]
JP 2001-341296 A
[Patent Document 7]
JP 2001-277490 A
[0018]
[Problems to be solved by the invention]
The present invention has been made in view of the above-described problems, and has been described in a functional element such as an EL element, a color filter, or a color conversion filter. And a method for manufacturing a functional element that can be formed to a difference that does not cause inconvenience such as uneven color tone, and an apparatus used for manufacturing such a functional element. It is the main purpose.
[0019]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention, in a method for producing a functional element having a base material and a functional layer formed in a pattern by an ejection method on the base material, on the base material, A coating step of applying a functional layer-forming coating liquid containing a solvent to form the functional layer in a pattern by a discharge method, and before the solvent is volatilized, rapidly applying the functional layer-forming coating liquid. And a rapid solidification step of solidifying the functional element.
[0020]
In the present invention, before the solvent is volatilized, by rapidly solidifying the coating liquid for forming a functional layer, it is possible to reduce the difference in film thickness between the center and the end of the functional layer, The film thickness can be made uniform. The functional element having such a functional layer has an effect of reducing the possibility of causing inconvenience such as uneven color tone.
[0021]
In the above invention, the solvent preferably has a boiling point in the range of 100 ° C to 300 ° C. If the boiling point is higher than the above range, it is difficult to completely remove the solvent in the rapid solidification step, and if the boiling point temperature is lower than the above range, handling may be difficult.
[0022]
Further, in the present invention, between the coating step and the rapid solidification step, a solvent volatilization suppressing means for suppressing volatilization of a solvent contained in a functional layer forming coating liquid applied on a substrate. It is preferable to use By providing such a solvent volatilization suppressing means, for example, even if some time is allowed from the application step to the rapid solidification step, the natural evaporation of the solvent can be suppressed, so the center of the functional layer This is because the difference between the thickness of the part and the thickness of the end part can be set to a degree that does not cause inconvenience such as uneven color tone.
[0023]
Further, in the present invention, the above-mentioned solvent volatilization suppressing means covers the lid-like structure so as to cover the surface of the functional layer-forming coating liquid from the upper surface of the base material coated with the functional layer-forming coating liquid. Preferably, it is the means used. This is because the evaporation of the solvent can be effectively suppressed by a simple method.
[0024]
In the present invention, in the rapid solidification step, the functional layer-forming coating liquid is preferably rapidly solidified by heating the substrate on which the functional layer-forming coating liquid is applied. This is because the functional layer-forming coating liquid can be rapidly solidified without complicated labor.
[0025]
In the present invention, it is preferable that the functional layer is a light emitting layer of an organic EL element, a colored layer of a color filter, or a color conversion layer of a color conversion filter. These members are particularly required to have uniform thickness, so that the effects of the present invention can be sufficiently utilized.
[0026]
Further, in order to achieve the above object, in the present invention, a coating means for applying a functional layer-forming coating liquid for forming a functional layer containing a solvent on a substrate by a discharge method, A lid-like structure that suppresses the volatilization of the solvent by covering the surface of the functional layer-forming coating liquid applied from the top surface, and rapidly solidifies the functional layer-forming coating liquid applied by the coating means. And a rapid solidifying means for producing the functional element.
[0027]
In the functional device manufacturing apparatus of the present invention, in order to rapidly solidify the functional layer forming coating liquid before the solvent is volatilized, by suppressing the volatilization of the solvent by providing a lid-like structure, further, Since the functional layer-forming solution coating liquid is rapidly solidified by the rapid solidification means, the difference in thickness between the center part and the end part of the functional layer can be reduced to a level that does not cause inconvenience such as uneven color tone. The functional layer can be planarized.
[0028]
In the above invention, the lid-like structure is a functional layer-forming coating liquid applied on a substrate after the functional layer-forming coating liquid is applied on the substrate by the coating means. Is preferably formed at a position where it can cover the surface of the functional layer-forming coating liquid applied on the substrate before being rapidly solidified by the rapid solidification means. By providing the lid-like structure in this way, the surface of the functional layer-forming coating liquid is immediately covered with the lid-like structure after the functional layer-forming coating liquid is applied by the application means. This is because volatilization of the solvent can be sufficiently suppressed and the effect of uniformizing the thickness of the functional layer can be obtained.
[0029]
Furthermore, in the present invention, the rapid solidifying means rapidly solidifies the functional layer forming coating liquid by heating a substrate having the functional layer forming coating liquid applied by the coating means. It is preferably a means. This is because the coating liquid for forming a functional layer can be rapidly solidified without particularly complicated work.
[0030]
In the present invention, it is preferable that the functional element is an organic EL element, a color filter, or a color conversion filter. This is because the member can make the most of the effects of the present invention.
[0031]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a method for manufacturing a functional element and an apparatus for manufacturing the same according to the present invention will be described.
[0032]
A. Method for manufacturing functional element
The method for producing a functional element of the present invention is a method for producing a functional element having a base material and a functional layer formed in a pattern on the base material by a discharge method. A coating step of applying a functional layer forming coating liquid for forming the functional layer in a pattern by a discharge method, and before the solvent is volatilized, rapidly solidify the functional layer forming coating liquid. And a rapid solidification step.
[0033]
In the present invention, before the solvent is volatilized, by rapidly solidifying the coating liquid for forming a functional layer, it is possible to reduce the difference in film thickness between the center and the end of the functional layer, Uniformity of the film thickness can be achieved. The functional element having such a functional layer has an effect of reducing the possibility of causing inconvenience such as uneven color tone.
[0034]
In the above invention, the boiling point of the solvent is preferably in the range of 100 ° C to 300 ° C, particularly preferably in the range of 150 ° C to 250 ° C. If the boiling point is higher than the above range, since it is difficult to completely remove the solvent in the rapid solidification step, the solvent will be contained in the functional layer finally obtained, and the functional layer Reliability will be greatly impaired. Further, a method of removing the solvent by heating at a higher temperature in the rapid solidification step can be considered, but this is not preferable because a problem such as deterioration of the material constituting the functional layer occurs. Further, if the temperature of the boiling point is lower than the above range, handling becomes difficult due to a change in viscosity due to the volatilization of the solvent during application, and even when a solvent volatilization suppressing means described later is provided, the volatilization of the solvent is suppressed. This is because a problem such as difficulty in performing the operation may occur.
[0035]
The method for manufacturing a functional element of the present invention having such advantages will be specifically described with reference to the drawings. FIG. 1 is a process chart showing an example of a method for manufacturing a functional element of the present invention.
[0036]
First, as shown in FIG. 1 (a), a functional layer forming solution coating liquid 3 for forming a functional layer is formed on a base material 2 on which a partition wall 1 is formed by a nozzle 4 using an inkjet method. Discharge. The functional layer forming coating liquid 3 applied between the partition walls 1 is held in a convex state by its own surface tension. Before the solvent contained in the functional layer forming coating liquid 3 is volatilized, the convex-shaped functional layer forming coating liquid 3 is forcibly applied as shown in FIG. Heat 5 to solidify rapidly. As described above, by rapidly solidifying the solvent before the solvent is volatilized, the difference in the film thickness between the end portion and the center portion is small and the film thickness is formed flat as shown in FIG. The functional layer 6 can be formed.
[0037]
Hereinafter, the method for manufacturing the functional element of the present invention will be described in detail for each process.
[0038]
1. Coating process
First, the coating step will be described. The application step in the present invention is a step of applying a coating liquid for forming a functional layer containing a solvent to form the functional layer on a substrate in a pattern by a discharge method.
[0039]
(1) Discharge method
An object of the present invention is to provide a functional layer formed by a discharge method, in which a difference in film thickness between an end portion and a central portion is reduced, and the film thickness is made uniform. In the present invention, the method for applying the functional layer-forming coating liquid for forming the functional layer is not particularly limited as long as it is a discharge method. Specifically, an ink jet method, a dispenser method, and the like can be given. In the present invention, among them, the inkjet method is preferable. This is because the inkjet method is a generally used ejection method, is excellent in material efficiency, and is advantageous in manufacturing efficiency.
[0040]
(2) Coating liquid for forming functional layer
Further, the functional layer formed in the present invention can include a light-emitting layer, a coloring layer, a color conversion layer, and the like. It becomes a coating liquid.
[0041]
Such a coating liquid for forming a functional layer is not particularly limited as long as it contains a solvent.However, in the present invention, the coating liquid for forming a functional layer is applied by a discharging method. It is preferable to use a material suitable for For example, the properties of the coating liquid used in the ink-jet method include a solvent containing a solvent, a low viscosity, and a relatively high boiling point. By using the coating liquid for forming a functional layer having the above properties, the coating liquid can be quickly discharged from the nozzle opening without any delay, and the coating liquid is prevented from remaining on the inner wall of the nozzle. This is because the application accuracy of the inkjet method can be improved from the side of the liquid.
[0042]
In addition, when a coating liquid for forming a functional layer having a low viscosity is used as described above, the coating liquid may be excessively wet when spread on a substrate due to the low viscosity of the coating liquid. Therefore, a method for preventing such excessive wetting and spreading of the coating liquid may be applied to the base material in advance. Examples of such a method include a method of providing a partition to prevent the progress of a coating liquid, and a method of providing a pattern forming layer on which a pattern is formed on a substrate by a difference in lyophilicity and lyophobic wettability, and the like. Can be mentioned.
[0043]
(3) Substrate
The substrate used in the present invention is appropriately selected depending on the use of the functional element in which the formed functional layer is used. In the case where the functional layer is a colored layer or a light emitting layer of an organic EL device, it may be necessary to be a transparent substrate. In this case, a material having high transparency is preferable, and an inorganic material such as glass is preferably used. Alternatively, a transparent resin or the like can be used.
[0044]
2. Rapid solidification process
Next, the rapid solidification step will be described. The rapid solidification step in the present invention is a step of rapidly solidifying the functional layer-forming coating liquid before the solvent contained in the above-described functional layer-forming coating liquid evaporates.
[0045]
In the present invention, before the solvent is volatilized by natural drying and drying proceeds, the coating liquid for forming a functional layer is solidified by this step, so that the difference in film thickness between the end and the center of the functional layer is obtained. Can be reduced, and the film thickness can be made uniform to such an extent that inconvenience such as uneven color tone does not occur.
[0046]
In this step, before the solvent contained in the coating liquid for forming a functional layer is volatilized, even if the solvent is volatilized to some extent, the solidification is performed by the present step, and the functional property is improved. As long as the difference in film thickness between the end and the center of the layer can be set to a level that does not cause inconvenience such as uneven color tone, the solvent is included before the solvent in the present invention is volatilized.
[0047]
The method for solidifying the coating liquid for forming a functional layer in this step is not particularly limited as long as the coating liquid for forming a functional layer can be solidified before the solvent is volatilized. Specifically, a method of arranging the substrate coated with the functional layer-forming coating liquid under reduced pressure, a method of heating, and the like are included.In the present invention, by heating, the functional layer-forming It is preferable to use a method of rapidly solidifying the coating liquid. Furthermore, the method of heating is not particularly limited as long as the temperature of the coating liquid for forming a functional layer can be easily raised and solidified. Therefore, a generally used heating method can be used, and specific examples include an oven, an infrared heater, and a hot plate. Among them, a hot plate or an infrared heater is preferable. This is because the hot plate conducts heat directly from the lower side of the base material, so that it has excellent thermal efficiency and less heating unevenness. Further, the infrared heater has a high penetration power and can uniformly heat the inside of the coating liquid for forming a functional layer.
[0048]
3. Solvent volatilization suppression means
In the present invention, in the functional layer forming coating liquid applied on the substrate, by performing the rapid solidification step before the solvent is volatilized, in the formed functional layer, the end and the center However, it is often difficult to perform a rapid solidification step immediately after the coating step, due to the structure of the apparatus. Therefore, in the present invention, between the above-mentioned coating step and the rapid solidification step, a solvent volatilization suppressing means for suppressing volatilization of a solvent contained in the functional layer forming coating liquid applied on the substrate is used. Is preferred.
[0049]
The solvent volatilization suppressing means used in the present invention is used between the above-mentioned coating step and the above-mentioned rapid solidification step, and is a means for suppressing the volatilization of the solvent occurring before the rapid solidification step.
[0050]
By providing such a solvent volatilization suppressing means, for example, even if some time is left between the application step and the rapid solidification step, it is possible to suppress spontaneous evaporation of the solvent occurring during such time. This is because the effect of reducing the difference in thickness between the center and the end of the functional layer can be enhanced.
[0051]
In the present invention, the solvent volatilization suppressing means is not particularly limited as long as it can suppress the volatilization of the solvent. For example, a method of arranging the entire substrate in a chamber saturated with the vapor of the solvent used for the functional layer forming coating liquid, a method of cooling the substrate, and the like can be mentioned. It is preferable to use a means using a lid-like structure so as to cover the surface of the functional layer-forming coating liquid from the upper surface of the substrate on which the layer-forming coating liquid has been applied.
[0052]
By covering the upper surface of the base material with the lid-like structure, the atmosphere around the surface of the coating liquid for forming the functional layer can be brought into a state close to a closed state, so that the volatile solvent quickly reaches a saturated state. Can be done. Therefore, the evaporation rate of the solvent is reduced, so that the evaporation of the solvent can be suppressed.
[0053]
Such a lid-shaped structure is not particularly limited as long as it can cover the surface of the functional layer-forming coating liquid applied on the substrate at a certain distance from the upper surface of the substrate. Is not done. Specifically, as shown in FIG. 2A, the lid-like structure 20 has a plate-like shape, or as shown in FIG. One that can cover not only the surface but also the side surfaces of the working liquid 3 can be used.
[0054]
Further, the material for forming the lid-like structure is not particularly limited, but is preferably a light-transmitting material so that the dry state of the solvent can be confirmed, and examples thereof include glass and quartz. . Among them, quartz is preferable in consideration of the pollution prevention effect.
[0055]
Further, when disposing the lid-like structure on the surface of the functional layer-forming coating liquid, the distance from the surface of the functional layer-forming coating liquid to the lid-like structure, specifically, FIG. 2, the interval A is preferably in the range of 1 mm to 10 mm, and more preferably in the range of 1 mm to 5 mm. If the distance is within the above range, the atmosphere near the surface of the coating liquid for forming a functional layer is close to a closed state, so that the volatile solvent easily reaches a saturated state, and the volatilization rate is promptly reduced. Because it can be.
[0056]
4. Functional element
The method for manufacturing a functional element of the present invention can manufacture various functional elements. However, the functional layer in the functional element manufactured by the above-described method for manufacturing a functional element is preferably a light emitting layer of an EL element, a colored layer of a color filter, or a color conversion layer of a color conversion filter. This is because, according to the present invention, a flattened functional layer in which the difference in film thickness between the central part and the end part of the functional layer is suitably small can be obtained, so that it can be used as an EL element, a color filter, or a color conversion filter. This is because the use thereof improves the element characteristics and enables high-definition color development.
[0057]
The color conversion filter referred to here is, for example, a color conversion filter that can convert a color into three primary colors, for example, red, green, and blue, when receiving blue or white light emission from a light emitting unit. It shows a filter having a layer, and may have a color filter for color correction as needed.
[0058]
Further, in the functional layer of the present invention, the difference in film thickness between the end portion and the center portion is not particularly limited as long as it does not cause inconvenience such as uneven color tone, but specifically, 5% to 30%. %, Among which it is preferable to be within a range of 5% to 10%. In a light-emitting layer of an EL element, an appropriate film thickness for effectively obtaining the function is about 50 nm to 100 nm, and in a color layer of a color filter or a color conversion layer of a color conversion filter, about 1 μm to 5 μm. Therefore, the difference in film thickness between the end portion and the center portion is specifically in the range of 2.5 nm to 30 nm, particularly, in the range of 2.5 nm to 10 nm in the case of the light emitting layer of the EL element. It is preferable that In the case of a coloring layer of a color filter or a color conversion layer of a color conversion filter, the thickness is preferably in the range of 50 nm to 1500 nm, and particularly preferably in the range of 50 nm to 500 nm. In the present invention, a functional element having excellent display characteristics can be provided because it can be easily formed with a film thickness difference within the above range.
[0059]
Further, as a display device provided by using the functional element manufactured by the method for manufacturing a functional element of the present invention, as shown in FIG. It can be used for a telephone 51, a PDA (Personal Digital Assistant) type terminal 52, a PC (Personal Computer) 53, a digital camera 54, and others (not shown) such as a television receiver and a video camera.
[0060]
B. Functional device manufacturing equipment
Next, an apparatus for manufacturing a functional element of the present invention will be described.
[0061]
An apparatus for producing a functional element of the present invention includes a coating means for applying a functional layer forming coating liquid for forming the functional layer containing a solvent by a discharge method, and a functional layer forming apparatus from the upper surface of the base material. A lid-like structure that covers the surface of the coating liquid to suppress the volatilization of the solvent, and the coating liquid for forming a functional layer applied by the coating means is rapidly solidified before the solvent is volatilized. And solidifying means.
[0062]
In the functional device manufacturing apparatus of the present invention, in order to rapidly solidify the functional layer forming coating liquid before the solvent is volatilized, by suppressing the volatilization of the solvent by providing a lid-like structure, further, Since the functional layer forming solution coating liquid is rapidly solidified by the rapid solidifying means, the difference in thickness between the central part and the end part of the functional layer should be formed to such an extent that inconvenience such as uneven color tone does not occur. Can be.
[0063]
An apparatus for manufacturing a functional element of the present invention having such advantages will be described with reference to the drawings. FIG. 3 is an explanatory view illustrating an example of a functional device manufacturing apparatus according to the present invention. The coating device 32 includes a nozzle 31 for discharging a functional layer forming coating liquid 30 and the like. A stage 34 for stably holding a substrate 33 on which the functional layer forming coating liquid 30 discharged from the nozzle 31 of the means 32 lands, and the functional layer forming coating liquid 30 is applied from the applying means 32. Thereafter, the lid-like structure 35 that can quickly cover the surface of the functional layer-forming coating liquid 30 and the base material 33 to which the functional layer-forming coating liquid 30 has been applied by the applying means 32 are placed below. A heat source 36 for heating from the side is shown. With the apparatus having such a configuration, the coating liquid for forming a functional layer can be rapidly solidified before the solvent is volatilized, and the functional layer can be easily flattened. Hereinafter, in the apparatus for manufacturing such a functional element, each unit will be described separately.
[0064]
1. Coating means
The application means in the present invention is not particularly limited as long as it is a means capable of applying a functional layer-forming coating liquid for forming a functional layer containing a solvent by a discharge method. Among them, an ink jet device is preferable. This is because the inkjet apparatus is the most widely used apparatus among the ejection apparatuses, is excellent in production efficiency as an application means, and enables application in a simple production process.
[0065]
2. Lid structure
The lid-like structure in the present invention is not particularly limited as long as it can suppress the volatilization of the solvent by covering the surface of the functional layer-forming coating liquid from the upper surface of the substrate.
[0066]
In the apparatus for manufacturing a functional element of the present invention, such a lid-like structure is coated with the functional layer-forming coating liquid on the substrate by the above-described coating means, and then immediately coated with the functional layer-forming coating liquid. There is no particular limitation on any part as long as it can be located on the surface of the working liquid. Specifically, after the lid-like structure is coated with the functional layer-forming coating liquid on the substrate by the coating means, the surface of the functional layer-forming coating liquid applied on the substrate is And it is preferably formed at a position where the surface of the functional layer-forming coating liquid applied on the substrate can be covered continuously before rapid solidification by the rapid solidification means. .
[0067]
For example, FIG. 3 shows an example in which the stage 34 that stably holds the base material 33 moves. In this case, when the stage 34 moves in the direction of the arrow, a functional layer formed by the coating unit 32 is formed. The application coating liquid 30 is applied in a direction opposite to the arrow. In this case, by providing the lid-like structure 35 at the position shown in FIG. 3, the surface of the functional layer forming coating liquid 30 can be covered with the lid-like structure 35 immediately after the application. In addition, as shown in FIG. 4, a case where the functional layer forming coating liquid 40 is applied in a reciprocating parallel manner, in which the stage 42 moves in the direction of the arrow after one line 41 is applied. In this case, as the movement of the stage 42 progresses, the lid-like structure 43 is provided so as to cover the surface of the functional layer forming coating liquid 40, so that the functional layer forming coating liquid The surface of the liquid 40 can be covered.
[0068]
Further, when covering the surface of the functional layer-forming coating liquid with the lid-like structure, the distance between the lid-like structure and the functional layer-forming coating liquid is determined by the above-mentioned “A. It is preferable to be within the range described in the section of “3. Solvent volatilization suppression means” in the “Production method”, but in order to adjust within such a range, the lid-like structure and the stage are relatively vertically moved. Preferably, means for moving are provided. For example, the case where the lid-like structure itself moves up and down, or the case where the stage itself moves up and down may be used.
[0069]
Other matters related to the lid-like structure are the same as those described in the above-mentioned item “A. Method for Manufacturing Functional Element”, and thus description thereof will be omitted.
[0070]
3. Rapid solidification means
The rapid solidification means in the present invention is not particularly limited as long as it can rapidly solidify the coating liquid for forming a functional layer applied on the base material before the solvent evaporates. Specifically, it is preferably a means for rapidly solidifying the functional layer-forming coating liquid by heating a substrate having the functional layer-forming coating liquid applied by the above-mentioned coating means. A commonly used heating device or the like can be used, and specific examples thereof include an oven, an infrared heater, and a hot plate. Among them, a heating device using a hot plate or an infrared heater is preferable. This is because the hot plate is a device that conducts heat directly from the lower side of the base material and dries it, and thus has excellent thermal efficiency and has less heating unevenness. Further, the infrared heater has a high penetration power and can uniformly heat the inside of the functional layer.
[0071]
Further, when heating the functional layer-forming coating liquid by the heating device, without affecting the coating means, the functional layer-forming coating liquid is maintained while maintaining suitable discharge conditions. It is preferable to heat the functional layer forming solution applied on the base material so that the solution can be applied. For example, before applying the functional layer-forming coating liquid by the coating means, in a method of heating the substrate in advance, the coating means itself is also heated by the heat, and the solvent is volatilized inside the coating means. In some cases, the concentration of the coating solution changes, and the discharge condition changes. In such a case, since the coating liquid for forming a functional layer adheres to the tip of the nozzle, there occurs a problem that ejection failure occurs frequently. Therefore, in order to avoid such inconveniences, when heating, the base material on which the functional layer forming coating liquid is applied on the surface after the functional layer forming coating liquid has landed on the base material. Preferably, the material is heated.
[0072]
Note that the present invention is not limited to the above embodiment. The above embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and has the same effect. Within the technical scope of
[0073]
【Example】
Hereinafter, the present invention will be further described with reference to Examples.
[0074]
[Example 1]
The following solutions were prepared as examples of the present invention.
(Preparation of coating liquid for forming organic EL layer)
・ 70 parts by weight of polyvinyl carbazole
・ Oxadiazole compound 30 parts by weight
・ Coumarin 6 (fluorescent dye) 1 part by weight
These were dissolved in tetralin (solvent) at 0.5% by weight to prepare an organic EL material ink for inkjet.
[0075]
When the fluorescent dye is coumarin 6, green light emission having a peak of 501 nm is obtained, in the case of perylene, blue light emission having a peak of 460 to 470 nm is obtained, and in the case of DCM, red light emission having a peak of 570 nm is obtained. Used as material.
[0076]
(Inkjet device)
As shown in FIG. 3, a device for producing a functional element having a coating means and a function of subsequently covering with a lid-like structure from above was produced. The lid-like structure was made of quartz. The distance between the nozzle and the substrate and the distance between the lid-like structure and the substrate can be independently adjusted. The stage was provided with a vacuum suction function so that the substrate could be fixed. A CCD camera was provided so that the state of discharge of the coating liquid from the coating means and heating and drying of the coating liquid could be observed. The head part where the nozzle and the lid-like structure are installed is fixed, and the X (vertical), Y (horizontal), Z (vertical), and θ (rotation) mechanisms allow the stage for fixing the base material to move in any direction. And a motor. An alignment function is provided for performing precise alignment with a nozzle by using an alignment mark on a substrate by a CCD camera. The parameters include the distance between the nozzle and the substrate, the distance between the lid-like structure and the substrate, the volume of one droplet of ink ejected from the nozzle, the number of droplets ejected per unit time, the stage movement speed, and the timing of ink ejection from the nozzle. Added variable setting.
[0077]
(Preparation of base material)
Using a polysilicon film on a glass substrate, an active matrix substrate for organic EL having a known pixel circuit configuration was prepared. A 17-inch diagonal substrate (300 mm × 370 mm in size) was designed to have a pixel design conforming to the XGA (768 × 1024) standard. As shown in FIG. 11, a substrate on which electrodes and the like were formed was prepared. FIG. 12 shows the structure of an actual display device in which pixels are arranged in a matrix. The partition was arranged so as to cover the electrode end so that the partition also served as the electrode insulating layer. As the electrode, a transparent electrode made of ITO was formed into a film and patterned by etching. The partition walls were formed by spin coating a photosensitive resist OFPR-800 (viscosity: 500 cp) manufactured by Tokyo Ohka Co., Ltd. at 1200 rpm, prebaking at 110 ° C, exposing and developing using a photomask, and postbaking at 240 ° C. Under the above conditions, the partition height (film thickness) could be formed to 6 μm. The shape of the partition thus formed can be easily confirmed using a scanning electron microscope (SEM) or the like. It was confirmed that the shape of the partition had a curved cross-sectional shape that was convex with respect to the substrate surface, and that the cross-sectional shape was a part of an arc.
[0078]
As shown in FIG. 13, the transparent electrode 130 is used for a bottom emission element structure, and a transparent substrate 131 is used to emit light 133 generated in the organic EL layer 132 by a transparent substrate opposite to the counter electrode 134. It can be obtained from the material 131 side. In addition, as shown in FIG. 14, the electrode 140 can be formed using a metal to form a top emission element structure. In this case, since the light emission 143 generated in the organic EL layer 141 is extracted from the counter electrode 142 side opposite to the base material 144, the counter electrode 142 needs to be transparent.
[0079]
(Production of organic EL display device)
After washing the substrate, PEDOT / PSS (polythiophene: Bayer CH8000) having a hole-injecting property was applied as a so-called buffer layer by spin coating to a thickness of 80 nm and baked at 160 ° C.
[0080]
The R, G, and B organic EL material inks are continuously discharged into the pixel openings on the PEDOT using the inkjet device, and the solvent is not dried on all the pixels on the base material by the step of covering with the lid-like structure. It was arranged in the state. Subsequently, the base material was moved together with the lid-like structure on a hot plate set at 100 ° C., and at the same time, the lid-like structure was removed and dried by heating to form three light-emitting layers in parallel. Ink jet device parameters were adjusted so that the flat film thickness after drying was 100 nm.
[0081]
Subsequently, an MgAg alloy (Mg: Ag = 10: 1) was deposited to a thickness of 150 nm, and Ag was deposited thereon as a protective layer to a thickness of 200 nm to form a negative electrode. As in this case, when manufacturing an active matrix display device using a TFT base material, the negative electrode is formed on the entire surface, and when manufacturing a passive matrix display device, a stripe is formed so as to be orthogonal to the electrode pattern on the base material. Form into shape.
[0082]
Finally, it was sealed with a separately prepared glass plate and a UV-curable sealing material to complete an organic EL display device.
[0083]
When a control circuit was connected to the organic EL display device thus manufactured and a video signal was input and driven, no emission failure due to uneven EL layer thickness occurred, and a uniform and vivid color image was obtained on the entire screen. Display was able to be performed.
[0084]
[Comparative example]
As a comparative example, an organic EL display device was manufactured in the same manner as in Example 1 except that the lid-like structure was removed. When a control circuit is connected to the organic EL display device and a video signal is input and driven, a large number of light-emission defective pixels resulting from unevenness in the thickness of the light-emitting layer are generated, and uniform image display can be performed. Did not. In addition, the luminance at the same applied voltage was greatly reduced, and the efficiency was also significantly reduced.
[0085]
[Example 2]
In Example 1, as shown in FIG. 4, the stage movement is a combination of the reciprocating movement and the parallel movement, and the stage moves as the nozzle linear movement is completed, and the base material moves below the lid-like structure. The operation was performed in the same manner as in Example 1 except that the structure of the ink jet apparatus was changed to 1.
[0086]
When a control circuit was connected to the organic EL display device thus manufactured and a video signal was input and driven, a uniform and vivid color image could be displayed on the entire screen as in Example 1.
[0087]
In the first embodiment, the stage can be moved only in one direction. In the second embodiment, the stage can be moved in both directions. Therefore, the throughput can be increased and the productivity can be increased. Was completed.
[0088]
[Example 3]
Example 1 was performed in the same manner as in Example 1 except that the stage was fixed and a mechanism of X (vertical), Y (horizontal), Z (vertical), θ (rotation) and a motor were provided so that the head could move in any direction. Thus, an organic EL display device capable of displaying a uniform and vivid color image on the entire screen as in Example 1 could be manufactured.
[0089]
[Example 4]
Example 2 was performed in the same manner as in Example 2 except that the stage was fixed and a mechanism of X (vertical), Y (horizontal), Z (vertical), θ (rotation) and a motor were provided so that the head could move in an arbitrary direction. As a result, an organic EL display device capable of displaying a uniform and vivid color image on the entire screen as in Example 2 could be manufactured. In the third embodiment, the head movement can be dealt with only in one direction. On the other hand, in the fourth embodiment, both head reciprocation can be dealt with. Was completed.
[0090]
[Example 5]
Except that the buffer layer PEDOT / PSS in Examples 1, 2, 3, and 4 was also selectively formed in the pixel openings by an inkjet method while also covering the buffer layer PEDOT / PSS with a lid-like structure to prevent solvent drying. Performed similarly.
[0091]
In the case of the spin coating in Examples 1, 2, 3, and 4, there was slight unevenness after the spin coating due to the influence of the partition surrounding the pixel. PEDOT film formation unevenness could be eliminated. Although the problem of non-uniformity of the film thickness inside the pixel of the PEDOT should have newly arisen simply by the ink-jet method, the lid-like structure was used similarly to the first, second, third and fourth embodiments. Due to the effect of covering with a substance and suppressing the volatilization of the solvent, it was possible to improve the uniformity within the substrate surface while maintaining the same display performance and efficiency as in the case of spin coating.
[0092]
[Example 6]
A color filter was manufactured in the same manner as in Example 1, Example 2, Example 3, and Example 4 except that the organic EL material was changed to a pigment dye. Conventionally, in a color filter manufactured by an ink-jet method, there was a problem of non-uniform color tone in a pixel due to non-uniform thickness of a colored layer, but in the present embodiment, it is preferable that non-uniform color tone does not occur. Color filters could be produced.
[0093]
As mentioned above, although the Example of this invention was described, this invention is not limited to this.
[0094]
【The invention's effect】
By using the present invention, before the solvent is volatilized, by rapidly solidifying the coating liquid for forming the functional layer, it is possible to reduce the difference in film thickness between the center and the end of the functional layer. And uniformity of film thickness can be achieved. The functional element having such a functional layer has an effect of reducing the possibility of causing inconvenience such as uneven color tone.
[Brief description of the drawings]
FIG. 1 is a process chart showing an example of a method for producing a functional element of the present invention.
FIG. 2 is a schematic sectional view showing an example of a lid-like structure according to the present invention.
FIG. 3 is an explanatory view showing an example of a functional device manufacturing apparatus of the present invention.
FIG. 4 is a schematic perspective view showing another example of the functional device manufacturing apparatus of the present invention.
FIG. 5 is a schematic perspective view showing an example of a display device using a functional element according to the present invention for a display unit.
FIG. 6 is a process chart showing an example of a conventional method for manufacturing a functional element.
FIG. 7 is a schematic diagram showing light emission unevenness as an example of a conventional inconvenience caused by unevenness of the film thickness of a functional element.
FIG. 8 is a schematic cross-sectional view showing an example of a disconnection occurring in a counter electrode in a conventional functional element.
FIG. 9 is a schematic cross-sectional view showing an example of a conventional functional element in which disconnection of a counter electrode is prevented by making a shape of a partition wall a curved surface.
FIG. 10 is a schematic sectional view showing an example of a conventional color filter.
FIG. 11 is a schematic diagram showing an example of arrangement of electrodes and the like in the embodiment.
FIG. 12 is a schematic diagram showing an example of the arrangement of pixels in the embodiment.
FIG. 13 is a schematic sectional view showing an example of a bottom emission element structure.
FIG. 14 is a schematic sectional view showing an example of a top emission element structure.
[Explanation of symbols]
1 ... partition wall
2 ... substrate
3 ... Coating liquid for forming functional layer
4… Nozzle
5 ... heating
6 ... functional layer

Claims (10)

In a method for producing a functional element having a base material and a functional layer formed in a pattern by a discharge method on the base material,
On a base material, a coating step of applying a functional layer forming coating liquid for forming the functional layer containing a solvent in a pattern by a discharge method,
A method for rapidly solidifying the coating liquid for forming a functional layer before the solvent is volatilized. The method for producing a functional element according to claim 1, wherein the boiling point of the solvent is in the range of 100C to 300C. Between the coating step and the rapid solidification step, a solvent volatilization suppressing unit that suppresses volatilization of a solvent contained in a functional layer forming coating liquid applied on a substrate is used. 3. The method for producing a functional element according to claim 1 or 2. The solvent volatilization suppressing means is means for covering the surface of the functional layer forming coating liquid applied from the upper surface of the base material coated with the functional layer forming coating liquid with a lid-like structure. The method for producing a functional element according to claim 3. The said rapid solidification process rapidly solidifies the coating liquid for functional layer formation by heating the base material with which the coating liquid for functional layer formation was applied. A method for manufacturing a functional element according to any one of claims 1 to 4. 6. The functional layer according to claim 1, wherein the functional layer is a light-emitting layer of an organic electroluminescent device, a colored layer of a color filter, or a color conversion layer of a color conversion filter. A method for manufacturing the functional element according to claim 1. A coating means for applying a functional layer-forming coating liquid containing a solvent to form a functional layer on a substrate by a discharge method, and a surface of the functional layer-forming coating liquid applied from the upper surface of the substrate A functional element comprising: a lid-like structure that suppresses volatilization of a solvent by covering the coating liquid; and a rapid solidification unit that rapidly solidifies the functional layer-forming coating liquid applied by the application unit. Manufacturing equipment. The lid-like structure may cover the surface of the functional layer-forming coating liquid applied on the substrate after the functional layer-forming coating liquid is applied on the substrate by the coating unit. 7. The coating liquid according to claim 6, wherein the coating liquid is formed at a position capable of covering the surface of the functional layer forming coating liquid applied on the base material before being rapidly solidified by the rapid solidification means. For manufacturing functional elements. The rapid solidification means is means for rapidly solidifying the functional layer forming coating liquid by heating a substrate having the functional layer forming coating liquid applied by the coating means. The functional device manufacturing apparatus according to claim 6 or 7, wherein: 9. The production of a functional device according to claim 6, wherein the functional device is an organic electroluminescent device, a color filter, or a color conversion filter. apparatus.

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