JP2004139814A - Coating device and method of manufacturing organic EL device using the same - Google Patents

Abstract

The present invention is suitable for a surface light source such as a backlight, a light source array of a printer or the like, has high luminance, has excellent storage durability, can have a large area, and can form a plurality of organic compound layers on a large substrate. Provided are an organic EL element and a coating device for an organic EL element that can be easily manufactured at a low cost and in a desired shape and size.
A coating apparatus using an air bearing system is used for transporting a substrate during coating. In order to maintain the parallel accuracy between the discharge port of the discharge type coater and the substrate at 10% or less of the gap, a fine adjustment mechanism equipped with a detecting means for measuring the gap between the coater head and the substrate by a laser displacement sensor is provided. Is preferred. Then, the organic EL material is applied using such an application device.
[Selection diagram] FIG.

Description

【００３２】
基板支持体６はエアベアリングによりコータヘッド７下を、印刷速度１５０ｍｍ／ｓで移動した。また、この際、基板とコータヘッドのギャップ１２０μｍ、コータヘッドの傾きは左右２点の高低差をレーザ変位センサ８にて測定し５μｍ以下に保ち、前記混合物を基板１上に０．０５μｍコーティングした。コーティング後の基板をそのまま乾燥装置に搬送し、常温にて自然乾燥を行った。外部への電極の取り出しのため、一部拭き取りＩＴＯを露出させ、続いて、発光層３として下記化学式２で表されるポリ［２−メトキシ−５−（２’−エチル−ヘキシロキシ）−１，４−フェニレン　ビニレン（Ｐｏｌｙ｛２−ｍｅｔｈｏｘｙ−５−（２‘−ｅｔｈｙｌｈｅｘｙｌｏｘｙ）−１，４−ｐｈｅｎｙｌｅｎｅ　ｖｉｎｙｌｅｎｅ｝　以下ＭＥＨ−ＰＰＶという）をシクロヘキサノンに溶解させ、０．１μｍコーティングした。
【００３３】
【化２】

【００３４】
コーティングは上記正孔注入層をと同条件で行った。同様に外部への電極取り出し部を拭き取り、真空蒸着機によりマグネシウム４を０．０１μｍ、アルミニウム５を０．５μｍ上着し、図１に示すような本発明からなる高分子ＥＬ素子を作製した。この高分子ＥＬ素子に５Ｖの電圧を印加したところ１００ｃｄ／ｍ２の均一な発光を得ることができた。
【００３５】
＜比較例１＞
実施例１において、コーティング装置としてボールベアリング方式を採用したダイコータを用い高分子ＥＬ素子を作製した。この高分子ＥＬ素子に５Ｖの電圧を印加したところ１００ｃｄ／ｍ２の発光を得たが、スジ状の膜厚ムラに起因する発光ムラが発生した。
【００３６】
＜比較例２＞
実施例１において、接触式変位センサにてコータヘッドの左右高低差を１５μｍとし、高分子ＥＬ素子を作製したが、発光層コーティング段階で、液がはじかれ、均一なコーティングを行うことができなかった。
【００３７】
【発明の効果】
本発明のような装置を用いることにより、塗布液のはじきや、膜厚ムラをなくすことができた。よって、この塗布装置を用いれば溶剤に溶解又は分散した有機ＥＬ材料を用いて有機ＥＬの製造において発生する、塗布液のはじきや、膜厚ムラに起因する発光ムラをなくすことができた。
【００３８】
【図面の簡単な説明】
【図１】本発明の高分子ＥＬ素子の一実施例を示す説明図である。
【図２】本発明の塗布装置の一実施例を示す説明図である。
【符号の説明】
１・・・ＩＴＯつきガラス基板
２・・・ＰＥＤＯＴ／ＰＳＳ
３・・・発光層
４・・・マグネシウム
５・・・アルミニウム
６・・・基板支持体
７・・・コータヘッド
８・・・レーザ変位センサ[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a coating apparatus and a method for manufacturing an organic EL device using an electroluminescence (hereinafter simply referred to as EL) phenomenon of an organic thin film using the coating apparatus.
[0002]
[Prior art]
An organic EL element is generally formed by laminating an anode, an organic light emitting layer, and a cathode. The organic light emitting layer may have a multilayer structure in which a hole injection layer, a hole transport layer, a phosphor layer, an electron injection layer, an electron transport layer, a buffer layer, and the like are stacked. When an electric current is passed between the anode and the cathode, light emission occurs in the organic light emitting layer, and light can be extracted to the outside by making one electrode transparent.
[0003]
The organic EL display device is a surface-emitting solid-state display device, and can be made thin. Since a display using this is a self-luminous type, it has a feature that it has a high viewing angle and high luminance, and can be driven at a low voltage. Further, it has a feature that the response speed is fast.
[0004]
However, each layer constituting the organic EL element requires a vacuum evaporation apparatus in which a plurality of evaporation vessels are connected, and the layers from the anode side to the cathode must be sequentially stacked. In addition, there are problems such as a decrease in light emission characteristics, a low productivity, and a high manufacturing cost due to poor vapor deposition efficiency.
[0005]
Also, many methods have been proposed in which an organic EL material is dissolved or dispersed in an organic solvent and a film is formed by a wet method using a printing method or a coating method.
[0006]
As a method using a printing method, a discharge type coater such as a screen printing method, a gravure printing method, a flexographic printing method, an offset printing method, an ink jet printing method, a spin coating method, a die coating method, a curtain coating method, a cap coating method, etc. The method used was mentioned.
[0007]
Examples of the method using a discharge type coater include a method of performing a rotation process after coating with a discharge type coater (Patent Document 1), and specifying a solvent and viscosity of an ink when using a discharge type coater (Patent Document 2). The invention has been made.
[0008]
[Patent Document 1]
JP 2001-351780 A [Patent Document 2]
Japanese Patent Application Laid-Open No. 2001-110348
However, in any of the printing methods and the coating methods, the organic EL element has a drawback that the thickness of the light emitting layer is very thin, about 0.1 μm, so that the thickness of the organic EL element tends to be uneven due to vibration or drying of the apparatus. Among them, the spin coating method, in which the membrane is produced with the centrifugal force applied and the centrifugal force continues to be applied until almost no solvent is left, is relatively unaffected by vibration and drying, and the most uniform This method is known as a method for forming a film, but is not practical because it has a drawback of wasting 95% or more of a material.
[0010]
The same is true for a method in which a discharge type coater and a rotation process are used in combination. The loss of material is as high as 50%, and it is hard to say that this method is suitable as a method for manufacturing an organic EL element that requires a high material cost.
[0011]
In addition, although provisions for ink when applying using a discharge type coater have been proposed, in practice, the vibration of the apparatus, drying conditions, and the parallelism (slope) of the coater head have a large effect, and cissing of the coating liquid may occur. It has been very difficult to solve the problems that the film thickness cannot be made uniform.
[0012]
[Problems to be solved by the invention]
As described above, an object of the present invention is to solve the above-described various problems in the related art and achieve the following objects. That is, the present invention is suitable for a surface light source such as a backlight, a light source array of a printer or the like, and has high luminance, excellent storage durability, can have a large area, and has a plurality of organic compound layers on a large substrate. An object of the present invention is to provide an organic EL element that can be formed, and a coating apparatus for an organic EL element that can be easily manufactured at a low cost and in a desired shape and size.
[0013]
[Means for Solving the Problems]
The present invention has been made in view of the above problems, and the invention according to claim 1 is a coating apparatus for forming a material dissolved or dispersed in a solvent on a substrate by a discharge type coater. The coating apparatus is characterized in that the transfer of the substrate uses an air bearing method.
The invention according to claim 2 is characterized in that a mechanism for finely adjusting the parallelism between the discharge port of the discharge type coater and the substrate is maintained at 10% or less of the gap. It is a coating device.
The invention according to claim 3 is characterized in that the mechanism for finely adjusting comprises a detecting means for measuring a gap between the coater head and the substrate by a laser displacement sensor. It is a coating device.
According to a fourth aspect of the present invention, in the method of manufacturing an organic EL using an organic material dissolved or dispersed in a solvent, the substrate is transported at the time of coating by applying the organic material using a coating device using an air bearing system. This is a method for manufacturing an organic EL element, which is a feature.
[0014]
According to the first aspect, the unevenness of the coating film due to the vibration can be eliminated by using the air bearing method, which is optimal for the production of the organic EL. According to the second aspect, repelling unevenness and uneven film thickness of the ink at the time of application are solved by controlling the parallel accuracy between the coater head and the substrate to 10% or less of the gap. Further, the inclination of the coater head is always monitored at the time of coating using a laser displacement sensor, and the parallel accuracy of the coater head and the substrate can be maintained by performing feedback control. Can be eliminated. Furthermore, according to the fourth aspect, it is possible to manufacture an organic EL having no light emission unevenness caused by uneven film thickness.
[0015]
The coating apparatus according to the present invention is an apparatus for coating a material dissolved or dispersed in a solvent by a discharge type coater (die coater), and uses an air bearing method for transporting a substrate during coating. Here, the air bearing system refers to a system in which a substrate or a support fixed to the substrate support is filled with gas or flows in so as to prevent the substrate or the substrate support from coming into contact with the apparatus main body.
[0016]
As the substrate according to the present invention, a glass substrate or a plastic film or sheet can be used. If a plastic film is used, the polymer EL can be manufactured by winding, and an element can be provided at low cost. As the plastic film, polyethylene terephthalate, polypropylene, cycloolefin polymer, polyamide, polyether sulfone, polymethyl methacrylate, polycarbonate, or the like can be used. Also, on the side where the conductive layer is not formed, a ceramic vapor-deposited film or another gas barrier film such as polyvinylidene chloride, polyvinyl chloride, saponified ethylene-vinyl acetate copolymer is laminated, or a color filter layer is provided by printing. May be.
[0017]
As the transparent conductive layer, a composite oxide of indium and tin (hereinafter referred to as ITO) can be used. By using a vapor deposition or sputtering method on the substrate, or by using a coating method such as printing paste-like ITO. A film can be formed. Alternatively, a precursor such as indium octylate or acetone indium can be formed on a substrate by a coating thermal decomposition method of forming an oxide by thermal decomposition after coating. Alternatively, a material in which a metal such as aluminum, gold, or silver is translucently evaporated can be used.
[0018]
The transparent or translucent conductive layer may be patterned by etching, if necessary, or activated on the surface by UV treatment, plasma treatment, or the like. Instead of etching, nitrocellulose, polyamide, vinyl chloride-vinyl acetate copolymer, ethylene-vinyl acetate copolymer, acrylic resin, urethane resin, or the like may be printed as an insulating layer.
[0019]
The polymer light-emitting layer that can be used in the present invention may be a single layer of a polymer phosphor or a multilayer structure including a hole transport layer, a polymer phosphor layer, and the like. When a hole transport layer is provided, copper phthalocyanine or a derivative thereof, 1,1-bis (4-di-p-tolylaminophenyl) cyclohexane, N, N′-diphenyl-N, N′-bis (3-methyl Phenyl) -1,1′-biphenyl-4,4′-diamine, N, N′-di (1-naphthyl) -N, N′-diphenyl-1,1′-biphenyl-4,4′-diamine and the like Can be used, but polyaniline, polythiophene, polyvinyl carbazole, a mixture of poly (3,4-ethylenedioxythiophene) and polystyrene sulfonic acid can be used to form a film by a wet method. Possible and more preferred.
[0020]
As the polymeric fluorescent substance layer, coumarin-based, perylene-based, pyran-based, anthrone-based, porphyrene-based, quinacridone-based, N, N'-dialkyl-substituted quinacridone-based, naphthalimide-based, N, N'-diaryl-substituted pyrrolopyrrole-based Using fluorescent dyes such as polystyrene, polymethyl methacrylate, and polyvinyl carbazole dissolved in polymers such as polyarylene, polyarylene ethynylene, polyarylvinylene, and dendrimer. Can be.
[0021]
These phosphor layers can be used alone or as a mixture of toluene, xylene, acetone, anisole, dimethylsulfoxide, dimethylformamide, tetralin, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, methanol, ethanol, isopropyl alcohol, ethyl acetate, ethyl acetate, butyl acetate, water, etc. A phosphor material can be dissolved in a solvent and a film can be formed using a printing method.
[0022]
When the phosphor layer is composed of two or more layers, in consideration of the solubility of the material constituting each layer, for example, utilizing the difference in solubility such as selecting a water-soluble and oil-soluble resin, The coating conditions may be selected so as to shorten the time from coating to drying so that the lower layer is not substantially affected. The thickness of the coating depends on the structure of the device, but is preferably 0.01 to 10 μm, and more preferably 0.05 to 0.5 μm. It should be noted that the organic EL material in this specification refers to an organic material that forms the above-described polymer phosphor layer, hole transport layer, polymer phosphor layer, and the like.
[0023]
In the organic EL device of the present invention, a phosphor layer is coated on a substrate on which a transparent or translucent conductive layer is laminated. Various coating methods such as a die coat, curtain coat, cap coat, spray coat, and slot coat can be used.
[0024]
In coating, if the parallel accuracy between the substrate and the coater head is poor, not only unevenness of film thickness but also unevenness of cissing often occur. For this reason, the gap between the substrate and the coater head is measured at two or more points using a contact type or optical type displacement meter (preferably a laser displacement sensor) by the detecting means, and the error of the inclination is 10% or less of the gap. Is desirable. Further, it is preferable that the gap is continuously measured by the optical displacement meter at the time of coating, and the coater head is controlled so as to be always parallel to the substrate. The gap is desirably 200 μm or less. The adjustment of the gap can be performed by slightly moving the coater head or the substrate (support) up and down by a piezo element or the like.
[0025]
In coating, only necessary portions may be coated, or portions not requiring coating may be protected by a release film or the like.
[0026]
In addition, the method of transporting a substrate during coating is not suitable for producing a thin film such as an organic EL even with a linear drive in a ball bearing method that is widely used, and unevenness due to micro-vibration occurs. It is preferable to use an air bearing system.
[0027]
Cathode materials include alkali metals such as lithium, sodium, and potassium, alkaline earth metals such as calcium, magnesium, and barium, as well as aluminum and yttrium, and alloys of these metals in consideration of energy levels and metal stability. And can be chosen arbitrarily. If necessary, a luminous efficiency can be increased by providing a buffer layer of lithium fluoride, alumina, polymethyl methacrylate, sodium polystyrene sulfonate, polystyrene, or the like.
[0028]
Further, a metal foil of aluminum, copper, nickel, or the like can be used as the cathode material. Similarly, if necessary, a luminous efficiency can be increased by providing a buffer layer of lithium fluoride, alumina, polymethyl methacrylate, sodium polystyrene sulfonate, polystyrene, or the like. For the buffer layer using a polymer such as polymethyl methacrylate or sodium polystyrene sulfonate, a wet printing method can be used.
[0029]
【Example】
Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto.
[0030]
This will be described with reference to FIG. 1 (the configuration of the organic EL) and FIG. 2 (coating device). The substrate 1 of 100 × 100 mm glass with ITO was suction-adsorbed to the substrate support 6 of the coating apparatus. A mixture (hereinafter referred to as PEDOT / PSS) of poly (3,4-ethylenedioxythiophene) and polystyrenesulfonic acid represented by the following chemical formula 1 is applied to the coater head (die coater) 7 of the coating apparatus as the hole injection layer 2. Introduced.
[0031]
Embedded image

[0032]
The substrate support 6 was moved under the coater head 7 by an air bearing at a printing speed of 150 mm / s. At this time, the gap between the substrate and the coater head was 120 μm, and the inclination of the coater head was kept at 5 μm or less by measuring the height difference between two points on the left and right with the laser displacement sensor 8, and the mixture was coated on the substrate 1 at 0.05 μm. . The coated substrate was transported as it was to a drying device and naturally dried at room temperature. In order to take out the electrode to the outside, a part of the ITO was wiped off to expose the ITO, and then as the light emitting layer 3, poly [2-methoxy-5- (2′-ethyl-hexyloxy) -1,1 represented by the following chemical formula 2 was used. 4-phenylenevinylene (Poly {2-methyoxy-5- (2'-ethylhexyloxy) -1,4-phenylene vinylene) (hereinafter referred to as MEH-PPV) was dissolved in cyclohexanone and coated with 0.1 μm.
[0033]
Embedded image

[0034]
Coating was performed under the same conditions as for the hole injection layer. Similarly, the electrode take-out part to the outside was wiped off, and magnesium 4 and aluminum 5 were coated on each other by 0.01 μm and 0.5 μm using a vacuum evaporation machine, thereby producing a polymer EL device according to the present invention as shown in FIG. When a voltage of 5 V was applied to this polymer EL device, uniform light emission of 100 cd / m2 was obtained.
[0035]
<Comparative Example 1>
In Example 1, a polymer EL element was manufactured using a die coater employing a ball bearing method as a coating apparatus. When a voltage of 5 V was applied to this polymer EL device, light emission of 100 cd / m2 was obtained. However, light emission unevenness caused by stripe-like film thickness unevenness occurred.
[0036]
<Comparative Example 2>
In Example 1, a polymer EL element was manufactured using the contact type displacement sensor with the height difference between the left and right of the coater head being 15 μm, but the liquid was repelled in the light emitting layer coating stage, and uniform coating could not be performed. Was.
[0037]
【The invention's effect】
By using the apparatus as in the present invention, repelling of the coating liquid and unevenness of the film thickness could be eliminated. Therefore, by using this coating apparatus, it was possible to eliminate the repelling of the coating liquid and the uneven light emission due to the uneven film thickness, which are generated in the manufacture of the organic EL using the organic EL material dissolved or dispersed in the solvent.
[0038]
[Brief description of the drawings]
FIG. 1 is an explanatory view showing one embodiment of a polymer EL device of the present invention.
FIG. 2 is an explanatory view showing one embodiment of a coating apparatus of the present invention.
[Explanation of symbols]
1 ... Glass substrate with ITO 2 ... PEDOT / PSS
Reference Signs List 3 Light-emitting layer 4 Magnesium 5 Aluminum 6 Substrate support 7 Coater head 8 Laser displacement sensor

Claims (4)

What is claimed is: 1. A coating apparatus for forming a film dissolved or dispersed in a solvent on a substrate by a discharge coater, wherein the substrate is transported at the time of coating using an air bearing method. 2. The coating apparatus according to claim 1, further comprising a mechanism for finely adjusting the parallelism between the discharge port of the discharge type coater and the substrate to be 10% or less of the gap. 3. The coating apparatus according to claim 1, wherein the fine adjustment mechanism includes a detection unit configured to measure a gap between the coater head and the substrate by using a laser displacement sensor. 4. A method of manufacturing an organic EL device using an organic material dissolved or dispersed in a solvent, wherein the substrate is transported during coating by applying the organic material using a coating device using an air bearing method. Method.

Images