JP4612973B2 - Method for manufacturing electroluminescent device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing an electroluminescent (hereinafter sometimes abbreviated as EL) element in which a light emitting layer is patterned by a printing method.
[0002]
[Prior art]
In the EL element, holes and electrons injected from opposing electrodes are combined in the light emitting layer, and the fluorescent material in the light emitting layer is excited with the energy to emit light of a color corresponding to the fluorescent material. It attracts attention as a self-luminous planar display element. Among them, organic thin-film EL displays using organic substances as light-emitting materials have high light-emission efficiency such as high-luminance light emission even when the applied voltage is less than 10 V, and can emit light with a simple element structure. It is expected to be applied to advertisements that display these patterns in light emission and other simple display displays at low cost.
[0003]
In manufacturing a display using such an EL element, patterning of an electrode layer or an organic EL layer is usually performed. As a patterning method of this EL element, there are a method of evaporating a luminescent material through a shadow mask, a method of coating by ink jet, and the like. However, these methods still have problems in the simplicity of the manufacturing process, the low utilization efficiency of materials, and the thinning to the optimum film thickness.
[0004]
In the former vapor deposition method, the thinner the shadow mask pattern is, the thinner the shadow mask is required, and the fine processing of the shadow mask is difficult. Furthermore, since accurate vapor deposition film formation is difficult due to the expansion / contraction and distortion of the shadow mask and the wraparound of the vapor deposition, a highly accurate vacuum apparatus is essential and there is a problem in terms of cost.
[0005]
Furthermore, the latter inkjet method has a problem in the simplicity of the manufacturing process, for example, it is necessary to perform a pretreatment on a structure for assisting patterning or a substrate on which a coating solution is applied.
[0006]
In particular, these problems have been a major problem when full-coloring EL elements, that is, when a plurality of color light-emitting layers must be formed.
[0007]
[Problems to be solved by the invention]
The present invention has been made in view of the above problems, and when manufacturing an EL device having a plurality of light emitting layers, a light emitting layer having a thin film and a uniform thickness can be formed. The main object is to provide a method of manufacturing an EL element capable of simplifying the above.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a light emitting layer forming coating solution for forming the light emitting layer by forming a light emitting layer constituting an EL element by a printing method as described in claim 1. The manufacturing method of the EL element characterized by having a viscosity of 0.5 cP or more and 500 cP or less is provided. By forming the light emitting layer by a printing method, the manufacturing process is simplified and the manufacturing efficiency is improved. Furthermore, by setting the viscosity of the coating liquid for forming the light emitting layer within the above range, the coating liquid can easily spread on the substrate and the thickness of the light emitting layer can be reduced.
[0009]
In the invention described in claim 1, as described in claim 2, the printing method is preferably intaglio printing. This is because in intaglio printing, the depth of the plate is a factor for controlling the film thickness, and the thickness of the light emitting layer can be easily reduced by adjusting the depth of the plate.
[0010]
In the invention described in the second aspect, as described in the third aspect, it is preferable that the depth of the groove or the cell of the intaglio is in the range of 500 angstrom to 1 mm. In intaglio printing, the viscosity of the coating liquid and the depth of grooves or cells in the intaglio are the factors controlling the film thickness. Therefore, it is possible to make the film thickness uniform and thin by setting the groove or cell depth within the above range together with the coating liquid in the above viscosity range.
[0011]
In the invention described in the second or third aspect, as described in the fourth aspect, the light emitting layer forming region of the intaglio is preferably formed by being divided into a plurality of cells.
[0012]
In the invention according to any one of claims 2 to 4, the entire area of the groove or the group of cells on the printing plate is formed on the substrate as described in claim 5. It is preferable that the light emitting layer be formed smaller than the area of the light emitting layer. In this way, by forming the entire area of the group of grooves or cells smaller than the area of the light emitting layer formed on the substrate, light emission having a predetermined film thickness and film quality is achieved by spreading on the substrate after printing. This is because a layer can be formed.
[0013]
In the invention according to any one of claims 1 to 5, as described in claim 6, the printing method comprises applying a light emitting layer forming coating liquid from a printing plate to a substrate. Either the direct printing method or the printing method of transferring the light emitting layer forming coating solution from the printing plate to the transfer material and printing the light emitting layer forming coating solution on the transfer material on the substrate is used. It is done. In the present invention, even a method using a transfer member as described above is applicable.
[0014]
In the invention according to any one of claims 1 to 6, as described in claim 7, at least one of a printing plate, a transfer body, a base material and an impression cylinder used in the printing method is used. One is preferably an elastic body. This is because when printing from a printing plate to a base material, for example, when unevenness is formed on the base material, either the printing plate or the base material is an elastic body. This is because printing can be performed, and this is the same when a transfer member is used.
[0015]
In the invention according to any one of the first to seventh aspects, as described in the eighth aspect, it is possible to separately coat the light emitting layer forming coating liquids of two or more colors. As a result, a full-color EL element can be manufactured.
[0016]
In the invention described in claim 8, as described in claim 9, when the light emitting layer of two or more colors is formed by a printing method, all of the light emitting layer forming coating liquids previously printed are formed. After solidifying, the coated portion may be covered with a protective material, and then the subsequent light emitting layer forming coating solution may be printed. When this method is used, when a subsequent coating liquid is applied, the previously applied application part is covered with a protective layer, so that the application part is not damaged by a printing plate or the like. This is because the light emitting layer can be patterned without any defects.
[0017]
In the invention described in claim 8, as described in claim 10, when the light emitting layer of two or more colors is formed by a printing method, all of the light emitting layer forming coating solutions previously printed are formed. You may make it print the subsequent coating liquid for light emitting layer formation before solidifying. When this method is used, when the subsequent coating liquid is applied, all of the previously applied coating liquids are not completely solidified, so that the previously applied coating liquid is damaged by a printing plate or the like. This is because it is possible to pattern the light emitting layer of two or more colors without any problem.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
In the method for producing an EL element of the present invention, the light emitting layer constituting the EL element is formed by a printing method, and the viscosity of the light emitting layer forming coating solution for forming the light emitting layer is 0.5 cP or more and 500 cP or less. The point that the light emitting layer is formed by a printing method, the point that the viscosity of the light emitting layer forming coating liquid is extremely low as described above, and further Such a low-viscosity coating liquid has a great feature in that a uniform thin-film-like light emitting layer can be formed by wetting and spreading. Hereinafter, a method for producing such an EL element of the present invention will be specifically described.
(Printing method)
First, the printing method used in the present invention will be described. In general, depending on the form of the printing plate used, the printing method can include types such as letterpress, intaglio, lithographic and stencil. In the present invention, a coating solution for forming a light emitting layer having a viscosity range as described above is used. Any printing method can be used as long as the printing method can be used. However, it is preferable to use an intaglio printing method using an intaglio because it is easy to control the film thickness of the resulting light emitting layer. Among the intaglio printing methods, it is particularly preferable to use gravure printing in consideration of the accuracy of the light emitting layer to be obtained.
[0019]
Thus, when the intaglio printing method is used, in the present invention, the depth of the groove or cell of the intaglio is preferably in the range of 500 angstroms to 1 mm, particularly in the range of 500 angstroms to 500 μm. This is because the thickness of the light emitting layer to be obtained can be optimized by setting the depth of the intaglio grooves or cells within this range.
[0020]
In the present invention, as described above, when printing using an intaglio plate, the shape of the intaglio plate is intended to obtain a line-shaped pattern from the printing plate, and to obtain an area-shaped pattern. And very different.
[0021]
For example, the width of the intaglio groove or cell for the purpose of obtaining a line-shaped pattern is preferably in the range of 1 μm to 1 mm, particularly in the range of 1 μm to 300 μm. By making the width of the intaglio trench or cell within this range, it becomes possible to adjust the line width of the pattern of the light emitting layer obtained to the required line width, and each pattern can be densely formed. is there.
[0022]
On the other hand, when the purpose is to obtain an area-like pattern, the width of the intaglio groove or cell is preferably in the range of 1 μm to 1 mm, particularly in the range of 1 μm to 300 μm. By making the width of the groove or cell within the above range, the light emitting layer forming coating solution printed on the base material is spread and spreads continuously, so that an area-like pattern can be formed without defects. is there.
[0023]
In addition, the interval between the grooves or cells in the intaglio for obtaining a line pattern is preferably 1 μm or more. This is because by setting the distance between the intaglio grooves or cells within this range, problems such as color mixing of the light emitting layer formed in a pattern can be avoided.
[0024]
On the other hand, when it is intended to form an area-like pattern, it is preferable that the intaglio groove or cell spacing is in the range of 1 μm to 10 mm, particularly in the range of 1 μm to 1 mm. This is because by setting the interval between the grooves or cells within the above range, the printed light-emitting layer forming coating solution can be spread and connected continuously, and an area-like pattern without defects can be obtained. .
[0025]
In the present invention, as shown in FIG. 1, it is preferable that a light emitting layer forming region of an intaglio corresponding to a light emitting layer formed on a substrate is formed by being divided into a plurality of cells. That is, it is preferable to form a light emitting layer on a substrate as shown in FIG. 1B using a pattern on a printing plate as shown in FIG. 1A.
[0026]
Moreover, in this invention, it is preferable that the whole area of the groove | channel or the group of a cell on the said printing plate is formed smaller than the area of the light emitting layer formed on a base material. In this way, by forming the entire area of the group of grooves or cells smaller than the area of the light emitting layer formed on the substrate, light emission having a predetermined film thickness and film quality is achieved by spreading on the substrate after printing. This is because a layer can be formed.
[0027]
Under the present circumstances, the total area of the group of the groove | channel or cell on a printing plate when the area of the light emitting layer formed on a base material is 100 is in the range of 10-98, especially in the range of 30-98. It is preferable to do.
[0028]
The shape of the cell in the printing plate used in the present invention is not particularly limited, and is a quadrangular shape, a triangular shape, a pentagonal shape, a hexagonal shape, a circular shape, a semicircular shape,
A hatched version or the like can be used.
[0029]
The printing plate making method may be any of conventional gravure, mesh gravure, electronic engraving gravure, and mill.
[0030]
The printing method in the present invention may be a method in which the light emitting layer forming coating solution is directly printed on the substrate from the printing plate, or the light emitting layer forming coating solution is transferred from the printing plate to the transfer body. A method of printing a light emitting layer forming coating solution on a transfer body on a substrate may be used. The transfer body used at this time may be plate-shaped or cylindrical.
[0031]
Furthermore, in the printing method used in the present invention, it is preferable that at least one of the base plate, the transfer body, and the impression cylinder that is the printing plate or the printing body is an elastic body. When a light emitting layer is formed by a printing method, the light emitting layer is often printed in a state where a layer such as an electrode layer or an insulating layer is formed on a substrate. When printing in such a state, if neither the printing plate nor the substrate has elasticity, it is not possible to cope with the unevenness on the substrate, and printing with good accuracy cannot be performed. is there.
[0032]
As described above, the present invention includes not only a method of printing directly on the base material from the printing plate but also a method of printing on the base material from the printing plate through the transfer body. It is preferable that at least one of the base material, the transfer body, and the impression cylinder that is a plate or a printing body is an elastic body.
[0033]
Here, the elastic body referred to in the present invention indicates a hardness of 10 ° to 90 ° according to JIS standard (JIS A).
[0034]
When the printing plate, impression cylinder or transfer body is an elastic body, a printing plate made of a material having elasticity as described above, for example, a synthetic rubber (acrylonitrile butadiene rubber, etc.) and a filler, a plasticizer, etc., An impression cylinder or a transfer body is used.
[0035]
On the other hand, as a case where the base material is an elastic body, a case where the base material is a resin base material can be exemplified. In this case, examples of the resin that can be used include polyethylene terephthalate (PET).
[0036]
In the present invention, the printing plate, the transfer body, and the impression cylinder may be either a roll shape or a plate shape as long as the printing method using the light emitting layer forming coating liquid in the viscosity range described above can be performed. It doesn't matter. Furthermore, regarding the base material, printing may be performed using a roll-like support in which a sheet-like base material is wound.
[0037]
FIG. 2 shows an example of the mechanism of a printing machine that can be used in the present invention. First, a roll-shaped plate cylinder 2 is placed at a position where a part of the roll is placed in an ink pan 1 that is a coating liquid supply unit.
[0038]
As described above, the plate cylinder 2 may be a roll or a plate. Specifically, a metal roll, a rubber roll, etc. can be mentioned, As a material to form, a synthetic rubber (acrylonitrile butadiene rubber etc.), ceramics, an ebonite, an electroconductive material etc. can be mentioned.
[0039]
Portions other than the grooves or cells of the plate may have water repellency. Thereby, removal of the coating liquid by a doctor becomes smooth.
[0040]
The plate cylinder 2 is provided with a doctor 3 for removing excess coating liquid. Examples of the material of the doctor 3 include stainless steel, synthetic rubber (such as acrylonitrile butadiene rubber), ceramics, ebonite, and conductive material.
[0041]
The coating liquid adhering to the plate cylinder 2 is transferred to the transfer body 4 as shown in FIG. Here, the transfer body 4 refers to a roll-like or plate-like one on which a coating liquid on the plate cylinder 2 is printed on a substrate, and examples thereof include a metal roll, a rubber roll, an anilox roll (engraving roll) and the like.
[0042]
And the coating liquid transcribe | transferred by the transfer body 4 is printed on the base material 5 which is a to-be-printed body. At this time, the base material 5 is disposed so as to pass between the transfer body 4 and the impression cylinder 6.
[0043]
Here, the impression cylinder 6 refers to a roll or a plate-like member that presses a substrate against a plate cylinder or a transfer body, and examples thereof include a metal roll and a rubber roll. Examples of the material include synthetic rubber (for example, acrylonitrile butadiene rubber).
[0044]
(Light emitting layer forming coating solution)
Next, the light emitting layer forming coating solution used in the present invention will be described. In the present invention, the light emitting layer is required to be uniform and thin. Therefore, the coating liquid needs to have a characteristic that it is thin and easily spreads. Therefore, in order to satisfy this requirement, the viscosity of the coating solution must be low.
[0045]
From this point of view, in the present invention, when forming a plurality of light emitting layers by the printing method as described above, the viscosity range of each light emitting layer forming coating solution is in the range of 0.5 cP to 500 cP, particularly It is preferably within the range of 0.5 cP to 200 cP. This is because when the viscosity of the coating solution for forming the light emitting layer is lower than the above range, the concentration of the light emitting material, which will be described later, becomes low, and a light emitting layer having a uniform film thickness cannot be obtained. In addition, when the viscosity is higher than the above range, there is a possibility that a uniform film thickness may not be ensured without sufficient wetting and spreading in the applied region, and it may be difficult to reduce the thickness of the light emitting layer. Because there is.
[0046]
Further, in order to obtain a uniform film that spreads sufficiently in the coated region, the solvent used in the coating solution has a boiling point of 60 ° C to 400 ° C, preferably 90 ° C to 300 ° C. Including Thereby, a coating liquid is leveled uniformly. Even in a low boiling point solvent of 100 ° C. or lower, the coating liquid is uniformly leveled by using the solvent atmosphere. After the coating liquid is transferred to the substrate, the drying process is performed after sufficient leveling.
[0047]
In addition, the surface tension of the light emitting layer forming coating solution used in the present invention is preferably in the range of 10 to 70 mN / m. It is because the contact angle with the base material mentioned later can be made into a predetermined range by setting it as this range.
[0048]
Such a light emitting layer forming coating solution used in the present invention is usually composed of a light emitting material, a solvent, and additives such as a dopant, and a light emitting layer of a plurality of colors is formed. Therefore, a plurality of types of light emitting layer forming coating solutions are used. Hereinafter, each material which comprises these light emitting layer forming coating liquids is demonstrated.
[0049]
A. Luminescent material
Examples of the light emitting material used in the present invention include a dye material, a metal complex material, and a polymer material.
[0050]
1. Dye-based material
Examples of dye-based materials include cyclopentamine derivatives, tetraphenylbutadiene derivatives, triphenylamine derivatives, oxadiazol derivatives, pyrazoloquinoline derivatives, distyrylbenzene derivatives, distyrylarylene derivatives, silole derivatives, thiophene ring compounds, pyridine rings Examples thereof include compounds, perinone derivatives, perylene derivatives, oligothiophene derivatives, trifumanylamine derivatives, oxadiazole dimers, pyrazoline dimers, and the like.
[0051]
2. Metal complex materials
As metal complex materials, aluminum quinolinol complex, benzoquinolinol beryllium complex, benzoxazole zinc complex, benzothiazole zinc complex, azomethylzinc complex, porphyrin zinc complex, europium complex, etc., the central metal, Al, Zn, Be etc. Examples thereof include a metal complex having a rare earth metal such as Tb, Eu, or Dy and having a oxadiazole, thiadiazole, phenylpyridine, phenylbenzimidazole, quinoline structure, or the like as a ligand.
[0052]
3. Polymer materials
Polymer materials include polyparaphenylene vinylene derivatives, polythiophene derivatives, polyparaphenylene derivatives, polysilane derivatives, polyacetylene derivatives, polyfluorene derivatives, polyvinylcarbazole derivatives, the above dye bodies, and metal complex light emitting materials. Can be mentioned.
[0053]
In the present invention, from the viewpoint of utilizing the advantage that the light emitting layer can be thinned by a printing method with the light emitting layer forming coating liquid in the above viscosity range, the above polymer material is used as the light emitting material. Is more preferable.
[0054]
B. solvent
As a solvent that dissolves or disperses the above-described light emitting material to form a light emitting layer forming coating solution, the above light emitting material is dissolved or dispersed and has a predetermined viscosity, surface tension, contact angle, and drying property. The solvent is not particularly limited as long as it can be used.
[0055]
Specifically, water, DMF, DMSO, alcohol, benzene, toluene, xylene isomers, trimethylbenzene isomers, tetramethylbenzene, tetralin, p-cymene, cumene, ethylbenzene, diethylbenzene isomers, Including butylbenzene, chlorobenzene, dichlorobenzene isomers, anisole, phenetole, butylphenyl ether, tetrahydrofuran, 2-butanone, 1,4-dioxashi, diethyl ether, diisopropyl ether, diphenyl ether, dipentyl ether, diglyme, etc. Chloric solvents such as ether solvents, dichloromethane, 1,1-dichloroethane, 1,2-dichloroethane, trichloroethylene, tetrachloroethylene, chloroform, carbon tetrachloride, 1-chloronaphthalene Medium, but cyclohexanone, may be used as long as conditions are satisfied solvent even this addition, it may be a mixed solvent of two or more.
[0056]
In the present invention, the contact angle of the light emitting layer forming coating liquid when the light emitting layer forming coating liquid is printed on the substrate (or transparent electrode layer) is also an important factor for obtaining suitable printing. It becomes. The contact angle in this case is, for example, within a range of 5 ° to 170 °, preferably 5 ° to 140 ° when a line-shaped light emitting layer is formed by a printing method, and an area-shaped light emitting layer is formed. In this case, the contact angle is preferably 30 ° or less, particularly preferably 20 ° or less.
[0057]
Such a contact angle is determined by the relationship between the material of the base material and the solvent constituting the light emitting layer forming coating solution. Considering this point, the solvent used in the light emitting layer forming coating solution in the present invention may be toluene in the case of the light emitting layer forming coating solution for forming a line-shaped light emitting layer. On the other hand, when an area-like light emitting layer is formed, xylene can be used.
[0058]
C. Additive
In addition to the light emitting material and solvent as described above, various additives can be added to the light emitting layer forming coating solution used in the present invention. For example, a doping material may be added for the purpose of improving the light emission efficiency in the light emitting layer or changing the light emission wavelength. Examples of the doping material include perylene derivatives, coumarin derivatives, rubrene derivatives, quinacridone derivatives, squalium derivatives, porphyrene derivatives, styryl dyes, tetracene derivatives, pyrazoline derivatives, decacyclene, phenoxazone, and the like.
[0059]
Moreover, you may add the additive etc. which can adjust the viscosity, surface tension, contact angle, or drying property of the light emitting layer forming coating liquid as needed.
[0060]
(Light emitting layer)
In the present invention, the light emitting layer is formed by the printing method using the above-described light emitting layer forming coating solution. The light emitting layer in the present invention may be one kind of light emitting layer, or a plurality of light emitting layers may be formed.
[0061]
In the present invention, the light emitting layer is formed so that the film thickness thereof is in the range of 100 angstroms to 10000 angstroms, preferably in the range of 100 angstroms to 2000 angstroms.
[0062]
The light emitting layer may be formed in a line shape as described above or may be formed in an area shape. In the present invention, being formed in a line means that the line width is 300 μm or less. On the other hand, in the present invention, forming in an area means that the line width exceeds 300 μm.
[0063]
(EL element)
The EL device manufacturing method of the present invention is characterized in that the light emitting layer is formed by using the above-described light emitting layer forming coating solution by the printing method as described above. The EL element obtained by the manufacturing method is composed of various organic EL layers, electrodes and the like in addition to such a light emitting layer. Hereinafter, these will be described.
[0064]
1. Base material
The EL device obtained by the EL device manufacturing method of the present invention is such that the above-described light emitting layer or the like is formed on a substrate. Such a substrate is not particularly limited as long as it has high transparency, and an inorganic material such as glass, a transparent resin, or the like can be used.
[0065]
The transparent resin is not particularly limited as long as it can be formed into a film, but a polymer material having high transparency, relatively high solvent resistance and heat resistance is preferable. Moreover, you may use the base material which has gas barrier property which interrupts | blocks gas, such as water vapor | steam and oxygen, as needed. Specifically, fluorine resin, polyethylene, polypropylene, polyvinyl chloride, polyvinyl fluoride, polystyrene, ABS resin, polyamide, polyacetal, polyester, polycarbonate, modified polyphenylene ether, polysulfone, polyarylate, polyetherimide, polyether mon Phon, Polyamideimide, Polyimide, Polyphenylene sulfide, Liquid crystalline polyester, Polyethylene terephthalate, Polybutylene terephthalate, Polyethylene naphthalate, Polymicroxylene dimethylene terephthalate, Polyoxymethylene, Polyethersulfone, Polyetheretherketone, Polyacrylate, Acrylonitrile -Styrene resin, phenol resin, urea resin, melamine resin, unsaturated polyester resin, Epoxy resins, polyurethane, silicone resin, amorphous polyolefins, and the like, may be used as long as satisfying the polymeric material also in this other, may be a copolymer of two or more kinds.
[0066]
In the present invention, when printing is performed using a printing plate or a transfer body, elasticity may be required for the substrate as described above. In this case, examples of the resin that can be used include the resins described in the section of the printing method.
2. Electrode layer
The EL element obtained by the present invention has a first electrode layer formed on a substrate and a second electrode layer formed on an organic EL layer such as the light emitting layer described above. Such an electrode layer is composed of an anode and a cathode, and either the anode or the cathode is transparent or translucent, and the anode is made of a conductive material having a large work function so that holes can be easily injected. preferable. A plurality of materials may be mixed. Each of the electrode layers preferably has a resistance as small as possible. Generally, a metal material is used, but an organic material or an inorganic compound may be used.
[0067]
Preferable anode materials include, for example, ITO, indium oxide, and gold. Preferred cathode materials include, for example, magnesium alloys (MgAg, etc.), aluminum alloys (AlLi, AlCa, AlMg, etc.), metallic calcium, and metals with a low work function.
[0068]
3. Organic EL layers other than light-emitting layers
In the EL device obtained in the present invention, a buffer layer, a hole transport layer, a hole injection layer, an electron transport layer, an electron injection layer, and the like may be combined as an organic EL layer in addition to the light emitting layer described above.
[0069]
4). Insulation layer
The EL device obtained by the present invention includes an insulating layer for covering the patterned edge portion of the first electrode layer formed on the substrate and the non-light emitting portion of the device, and preventing a short circuit at a portion unnecessary for light emission. May be provided in advance such that the light emitting portion is an opening. By doing in this way, the element by which the defect by the short circuit etc. of an element is reduced and the light emission is stable with a long lifetime is obtained.
[0070]
Such an insulating layer can be patterned using, for example, a UV curable resin material or the like, as is generally known.
[0071]
(Manufacturing method of EL element)
Finally, a general process flow in the method for manufacturing an EL element of the present invention will be described.
[0072]
First, if necessary, an insulating layer is formed on a substrate on which the first electrode layer has been patterned in advance so as to cover the edge portion of the first electrode layer. Next, after forming an organic EL layer such as a buffer layer as necessary, a plurality of light-emitting layer forming coating liquids are printed for each color using a printing method.
[0073]
The printing method at this time is not particularly limited as described above, but a printing method using an intaglio is preferably used. When using the intaglio as described above, the coating liquid for forming the light emitting layer having the above-described viscosity is attached to the concave portion of the plate by dipping or the like, and then the excess coating liquid is scraped off using a doctor blade or the like. Printed on the substrate.
[0074]
In the present invention, the light emitting layer forming coating solution for forming light emitting layers of two or more colors can be separately printed on the substrate by printing the light emitting layer forming coating solution on the substrate. . As a result, a full-color EL element can be finally produced.
[0075]
As described above, when the light emitting layer forming coating liquid for forming two or more colors of light emitting layers is continuously printed, it is necessary to perform the next printing without damaging the previously printed light emitting layer. At this time, it is preferable to use the following two methods.
[0076]
In the first method, when the light emitting layer of two or more colors is formed by a printing method, after all of the light emitting layer forming coating liquid printed in advance is solidified, the coated portion is covered with a protective material, and then The light emitting layer forming coating solution is printed. The protective material used here may be formed of any material or forming method as long as it can be patterned so as not to be formed in a region where a subsequent light emitting layer forming coating solution is applied.
[0077]
In the present invention, for example, there may be mentioned a method in which a film-like protective material is applied to the coated portion after coating and solidified, and then peeled after coating a light emitting layer forming coating solution.
[0078]
The material that can be used for such a protective material is not particularly limited as long as it can be molded on a film, but a polymer material that does not stretch or distort or has a relatively small size is preferable. Specifically, fluorine resin, polyethylene, polypropylene, polyvinyl chloride, polyvinyl fluoride, polystyrene, ABS resin, polyamide, polyacetal, polyester, polycarbonate, modified polyphenylene ether, polysulfone, polyarylate, polyetherimide, polyether mon Phon, Polyamideimide, Polyimide, Polyphenylene sulfide, Liquid crystalline polyester, Polyethylene terephthalate, Polybutylene terephthalate, Polyethylene naphthalate, Polymicroxylene dimethylene terephthalate, Polyoxymethylene, Polyethersulfone, Polyetheretherketone, Polyacrylate, Acrylonitrile -Styrene resin, phenol resin, urea resin, melamine resin, unsaturated polyester resin, Epoxy resins, polyurethane, silicone resin, amorphous polyolefins, and the like, may be used as long as satisfying the polymeric material also in this other, may be a copolymer of two or more kinds.
[0079]
When such a method is used, when the subsequent coating liquid is applied, the previously applied application portion is covered with a protective material, so that the two colors without damaging the application portion with a printing plate or the like. It becomes possible to pattern the above light emitting layer without a defect.
[0080]
On the other hand, the second method is a method in which the subsequent coating liquid is printed before all of the previously printed coating liquid is solidified. This is because, when the next printing is started after the previously printed coating liquid has completely solidified, there is a possibility that a problem such as peeling off of the part that comes into contact with the printing plate may occur.
[0081]
In the present invention, “before the light emitting layer forming coating solution is solidified” indicates a state in which the coating solution can be leveled before the drying step. On the other hand, “after the light emitting layer forming coating solution is solidified” refers to a state after the drying step. All drying steps are performed after the coating solution is sufficiently leveled.
[0082]
After forming the light emitting layer in this manner, a second electrode layer is formed so as to cover the display region, and finally, sealing for moisture prevention is performed to complete the EL element.
[0083]
In addition, this invention is not limited to the said embodiment. The above-described embodiment is an exemplification, and the present invention has any configuration substantially the same as the technical idea described in the claims of the present invention and exhibits the same function and effect. Are included in the technical scope.
[0084]
【Example】
The following examples further illustrate the invention.
[0085]
[Example 1]
<Preparation of light emitting layer forming coating solution>
The polymeric fluorescent substance 1 was dissolved in xylene and adjusted to have a viscosity of 0.5 cP to prepare a light emitting layer forming coating solution 1. Furthermore, the polymeric fluorescent substance 2 which shows the luminescent color different from the polymeric fluorescent substance 1 was dissolved in xylene, and adjusted so that a viscosity might be set to 0.5 cP, and the light emitting layer forming coating liquid 2 was prepared. Here, the polymeric fluorescent substance 1 indicates a light emitting material made of polyvinylcarbazole + coumarin derivative, and the polymeric fluorescent substance 2 shows a light emitting material made of polyvinylcarbazole + perylene derivative.
[0086]
<Production of element>
150mm sq., 400μm thickness, 40Ω surface resistivity (made by Geomat Co., Ltd.) ITO film-formed polycarbonate base material, using a spin coater as a hole injection layer polystyrene sulfonate / poly (3,4) ethylenedi Oxythiophene (PSS / PEDOT) was deposited to a thickness of 100 nm. Further, this formed film was dried at 100 ° C. under reduced pressure for 1 hour.
[0087]
After drying, first, the light emitting layer forming coating solution 1 of the light emitting material is used with a simple gravure printing machine (GP-10, manufactured by Kurabo Industries) using a printing plate having a plate groove width of 1 mm, a bank width of 10 mm, and a plate depth of 1 mm. A gravure printing method was used to form a film with a thickness of 30 mm × 60 mm and a film thickness of 100 nm.
[0088]
Then, the light emitting layer forming coating solution 2 using a light emitting material different from the light emitting layer forming coating solution 1 was continuously formed in a region other than the portion applied for the first time. At this time, the light emitting layer forming coating solution 2 was printed (applied) before the light emitting layer forming coating solution 1 was completely solidified.
[0089]
As a result, on the same 150 mm square ITO film-formed polycarbonate, layers having different emission colors were separately formed with a thickness of 30 mm × 60 mm and a film thickness of 100 nm.
[0090]
Further, this light emitting layer coating film was dried at 80 ° C. under reduced pressure for 1 hour, and then 5 nm of calcium was formed as the second electrode layer, and silver was vacuum-deposited thereon by 250 nm to produce an EL device.
[0091]
[Example 2]
<Preparation of light emitting layer forming coating solution>
The polymeric fluorescent substance 1 was dissolved in xylene and adjusted to have a viscosity of 250 cP to prepare a light emitting layer forming coating solution 3. Furthermore, the polymeric fluorescent substance 2 was dissolved in xylene and adjusted to have a viscosity of 250 cP to obtain a light emitting layer forming coating solution 4.
[0092]
<Production of element>
150mm sq., 400μm thickness, 40Ω surface resistivity (made by Geomat Co., Ltd.) ITO film-formed polycarbonate base material, using a spin coater as a hole injection layer polystyrene sulfonate / poly (3,4) ethylenedi Oxythiophene (PSS / PEDOT) was deposited to a thickness of 100 nm. Further, this formed film was dried at 100 ° C. under reduced pressure for 1 hour.
[0093]
After drying, first, the light emitting layer forming coating solution 3 is formed using a printing plate having a plate groove width of 8 μm, a bank width of 4 μm and a plate depth of 2 μm using a simple gravure printing machine (GP-10, manufactured by Kurabo Industries). A film was formed by gravure printing at 30 mm × 60 mm and a film thickness of 100 nm. Subsequently, the said light emitting layer forming coating liquid 4 was formed into a film except the part apply | coated 1st time. At this time, the light emitting layer forming coating solution 4 was printed before the light emitting layer forming coating solution 3 was completely solidified.
[0094]
As a result, on the same 150 mm square ITO film-formed polycarbonate, layers having different emission colors were separately applied with a thickness of 30 mm × 60 mm and a film thickness of 100 nm.
[0095]
Further, this light-emitting layer coating film was dried at 80 ° C. under reduced pressure for 1 hour, and then 5 nm of calcium was formed as the second electrode layer, and silver was vacuum-deposited thereon to 250 nm to produce an EL device.
[0096]
[Example 3]
<Preparation of light emitting layer forming coating solution>
The polymeric fluorescent substance 1 was dissolved in xylene and adjusted so as to have a viscosity of 500 cP, whereby a light emitting layer forming coating solution 5 was obtained. Furthermore, the polymeric fluorescent substance 2 which shows a luminescent color different from that of the polymeric fluorescent substance 1 was dissolved in xylene and adjusted so as to have a viscosity of 500 cP to obtain a light emitting layer forming coating solution 6.
[0097]
<Production of element>
150mm sq., 400μm thickness, 40Ω surface resistivity (manufactured by Geomat Co., Ltd.) ITO film-formed polycarbonate base material, using a spin coater as a hole injection layer polystyrene sulfonate / poly (3,4) ethylenedi Oxythiophene (PSS / PEDOT) was deposited to a thickness of 100 nm. Further, this formed film was dried at 100 ° C. under reduced pressure for 1 hour. After drying, first, the light emitting layer forming coating solution 51 is gravure-printed using a printing plate having a plate groove width of 5 μm, a bank width of 1 μm, and a plate depth of 500 Å using a simple gravure printing machine (GP-10, manufactured by Kurabo Industries). After the film formation by printing with a thickness of 30 mm × 60 mm and a film thickness of 100 nm, the light emitting layer forming coating solution 6 of a light emitting material different from the light emitting color of the light emitting layer forming coating solution 5 is continuously applied for the first time. The film was formed in a region other than the part where the film was formed. As a result, on the same 150 mm square ITO film-formed polycarbonate, layers having different emission colors were separately formed with a thickness of 30 mm × 60 mm and a film thickness of 100 nm.
[0098]
Further, this light emitting layer coating film was dried at 80 ° C. under reduced pressure for 1 hour, and then 5 nm of calcium was formed as the second electrode layer, and silver was vacuum-deposited thereon by 250 nm to produce an EL device.
[0099]
[Comparative Example 1]
<Adjustment of light emitting layer forming coating solution>
The polymeric fluorescent substance 1 was dissolved in xylene and adjusted to have a viscosity of 0.4 cP to obtain a light emitting layer forming coating solution 7.
[0100]
<Production of element>
150mm sq., 400μm thickness, 40Ω surface resistivity (manufactured by Geomat Co., Ltd.) ITO film-formed polycarbonate base material, using a spin coater as a hole injection layer polystyrene sulfonate / poly (3,4) ethylenedi Oxythiophene (PSS / PEDOT) was deposited to a thickness of 100 nm. Further, this formed film was dried at 100 ° C. under reduced pressure for 1 hour. After drying, first, the light emitting layer forming coating solution 7 is obtained by gravure printing using a printing plate having a plate groove width of 1 mm, a bank width of 5 mm, and a plate depth of 2 mm with a simple gravure printing machine (GP-10, manufactured by Kurabo Industries). A film was formed. Since the amount of the polymeric fluorescent substance in the light emitting layer forming coating solution 7 was small, a uniform light emitting layer film could not be obtained.
[0101]
[Comparative Example 2]
<Preparation of light emitting layer forming coating solution>
The polymeric fluorescent substance 1 was dissolved in xylene and adjusted to have a viscosity of 550 cP to obtain a light emitting layer forming coating solution 8.
[0102]
<Production of element>
150mm sq., 400μm thickness, 40Ω surface resistivity (manufactured by Geomat Co., Ltd.) ITO film-formed polycarbonate base material, using a spin coater as a hole injection layer polystyrene sulfonate / poly (3,4) ethylenedi Oxythiophene (PSS / PEDOT) was deposited to a thickness of 100 nm. Further, this formed film was dried at 100 ° C. under reduced pressure for 1 hour. After drying, first, the light emitting layer forming coating solution 8 is formed by gravure printing using a simple gravure printing machine (GP-10, Kurabo Industries Co., Ltd.) using a plate groove width of 8 μm, a bank width of 1 μm, and a plate depth of 300 Å. Filmed. Since the viscosity in the light emitting layer forming coating solution 8 was high, a uniform light emitting layer film could not be obtained.
[0103]
【The invention's effect】
According to the present invention, by forming the light emitting layer by a printing method, the manufacturing process is simplified and the manufacturing efficiency is improved. Furthermore, by making the viscosity of the coating liquid for forming the light emitting layer within the above range, the coating liquid can easily spread on the substrate, and the thickness of the light emitting layer can be reduced. Play.
[Brief description of the drawings]
FIG. 1 is a schematic plan view for explaining an intaglio pattern used in the present invention.
FIG. 2 is a schematic side view showing an example of a printing apparatus used in the present invention.
[Explanation of symbols]
1 ... Ink pan
2 ... Plate cylinder
3 ... Doctor
4 ... Transcript
5 ... Base material
6 ... impression cylinder

Claims (8)

A method for producing an electroluminescent element in which a light emitting layer constituting an electroluminescent element is formed by a printing method ,
The viscosity of the light-emitting layer forming coating solution for forming the light emitting layer state, and are more 500cP less 0.5 cP,
The printing method is a printing method using an intaglio,
The method for manufacturing an electroluminescent element, wherein the light emitting layer forming region of the intaglio is formed by being divided into a plurality of cells . 2. The method of manufacturing an electroluminescent device according to claim 1 , wherein a depth of the intaglio groove or cell is in a range of 500 Å to 1 mm. 3. The electroluminescent device according to claim 1 , wherein the total area of the groove or the group of cells on the printing plate is smaller than the area of the light emitting layer formed on the substrate. Device manufacturing method. The printing method is a method of directly printing a light emitting layer forming coating solution on a substrate from a printing plate, or a method of transferring a light emitting layer forming coating solution from a printing plate to a transfer body to form a light emitting layer on the transfer body. The method for manufacturing an electroluminescent element according to any one of claims 1 to 3, wherein the printing method is any one of a method of printing a coating liquid on a substrate. The electroluminescence according to any one of claims 1 to 4 , wherein at least one of the printing plate, the transfer body, the substrate, and the impression cylinder used in the printing method is an elastic body. A manufacturing method of a cent element. The method for producing an electroluminescent element according to any one of claims 1 to 5 , wherein a coating solution for forming a light emitting layer for two or more colors can be separately applied. When the light emitting layer of two or more colors is formed by a printing method, after all the light emitting layer forming coating liquids that have been printed are solidified, the coated portion is covered with a protective material, and then the light emitting layer forming coating is subsequently formed. The manufacturing method of the electroluminescent element according to claim 6 , wherein the working liquid is printed. When forming the light emitting layer of two or more colors by a printing method, the subsequent light emitting layer forming coating liquid is printed before all the light emitting layer forming coating liquids previously printed are solidified. The manufacturing method of the electroluminescent element of Claim 6 .

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