JP4491942B2 - ELECTROLUMINESCENT DEVICE AND METHOD FOR MANUFACTURING THE SAME - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electroluminescence element (hereinafter, referred to as an EL element) that is expected to be widely used as a display such as an information display terminal or a surface-emitting light source.
[0002]
[Prior art]
The EL element is expected as a flat panel display that replaces a cathode ray tube or a liquid crystal display because of advantages such as a wide viewing angle, a high response speed, and low power consumption.
[0003]
The EL element has a structure in which an organic or inorganic light-emitting medium layer is sandwiched between two electrodes, at least one of which is transparent, and light is emitted from the light-emitting medium layer by applying a voltage between both electrodes. (Hereinafter, an example in which voltage is applied to the organic light-emitting medium layer will be described).
[0004]
When the EL element is left in a state where the light emitting medium layer and the cathode layer are exposed to the atmosphere, the EL element deteriorates due to moisture and oxygen in the atmosphere. As one specific example, there is a phenomenon in which a non-light emitting region called a dark spot occurs and expands with the passage of time.
[0005]
As methods for solving this problem, there are descriptions in JP-A-5-182759 and JP-A-5-36475. In these methods, a luminescent medium layer and a cathode layer are continuously formed under vacuum on a glass substrate on which a transparent anode layer is formed, and an EL element is covered and sealed in a dry nitrogen atmosphere with a metal or glass sealing can. Is the method.
[0006]
However, in order to manufacture such an EL element, a plurality of vacuum deposition apparatuses capable of transporting a glass substrate under vacuum and a sealing apparatus under nitrogen are necessary, so that productivity is low and manufacturing cost is high. There was a problem. Further, since a glass substrate or a metal sealing can is used, there is a limit to reducing the thickness and weight of the element.
[0007]
As a means for solving this problem, a method has been proposed in which a light emitting medium layer or a cathode layer is wound on a plastic film by vapor deposition or printing, and the EL element is covered and sealed with a moisture-resistant film. . This makes it possible to manufacture a thin and lightweight EL element at low cost.
[0008]
Since the moisture-resistant film is disposed on the side opposite to the EL light extraction surface, the moisture-resistant film does not need to be translucent, and a moisture-resistant film made of a metal foil particularly excellent in moisture resistance can be used. On the other hand, since the plastic film on the EL light extraction surface side is required to have moisture resistance and translucency, a technique of depositing a transparent inorganic thin film on the plastic film or laminating a transparent inorganic thin film deposited film is employed. However, the current transparent inorganic thin film deposited film cannot suppress the deterioration of the EL element over a long period of time.
[0009]
[Problems to be solved by the invention]
In the present invention, it is made to solve the above-mentioned problems, and the place to be the subject is to produce an EL element by film winding and then seal it with a glass substrate and a moisture resistant film. An object of the present invention is to provide an inexpensive EL element and a manufacturing method thereof by blocking moisture from the outside, suppressing deterioration of the EL element over a long period of time, and improving productivity.
[0010]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention firstly in claim 1, at least a transparent anode layer, a light emitting medium layer, and a cathode layer are sequentially laminated on one surface of a plastic substrate, and the laminate is formed of a moisture-resistant film. In the electroluminescent element formed by covering and sealing, the electroluminescent element is characterized in that a glass substrate is laminated on the other surface of the plastic substrate, and the moisture-resistant film is thermocompression bonded to the glass substrate. .
According to a second aspect of the present invention, at least a transparent anode layer, a light emitting medium layer, and a cathode layer are sequentially laminated on one surface of a plastic substrate, a step of forming an extraction electrode on the glass substrate, and the glass substrate is made of a plastic substrate. The step of laminating on the other surface of the material, the step of electrically connecting the extraction electrode to the transparent anode layer and the cathode layer, and the glass substrate on which the extraction electrode is formed and the moisture-resistant film are covered and sealed by thermocompression bonding A method for producing an electroluminescent element, comprising at least a step.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an example of the EL element of the present invention and its manufacturing process will be described with reference to FIG.
[0012]
In the present embodiment, as the plastic substrate 1, a stretched or unstretched film or sheet made of polyethylene terephthalate, polypropylene, polyethersulfone, polycarbonate, cycloolefin polymer, polyarylate, polyamide, polymethyl methacrylate, or the like is used. be able to. Further, before the transparent anode layer is formed on these plastic films, surface treatment such as corona treatment, plasma treatment, or UV ozone treatment may be performed.
[0013]
First, the transparent anode layer 2 is wound on the plastic substrate 1 by sputtering or vacuum deposition, and then the transparent anode layer is formed while winding the film using a photolithography method and a wet etching method. Patterning is performed to form the transparent anode layer 2 also serving as the anode lead electrode 2a and the cathode lead electrode 2b. Alternatively, the transparent anode layer may be patterned by mask vapor deposition.
[0014]
As a material of the transparent anode layer 2 in the present invention, ITO (indium tin composite oxide), indium zinc composite oxide, zinc aluminum composite oxide, or the like can be used. Further, in order to reduce the wiring resistance of the transparent anode layer, a metal material such as copper or aluminum may be provided as an auxiliary electrode in the transparent anode layer.
[0015]
Next, the light emitting medium layer 3 is wound on the transparent anode layer 2 to form a film. The light emitting medium layer 3 in the present invention can be formed of a single layer film containing a fluorescent material or a multilayer film. Examples of the structure of the light-emitting medium layer in the case of forming a multilayer film include a hole transport layer, an electron transport light-emitting layer or a hole transport light-emitting layer, a two-layer structure comprising an electron transport layer, a hole transport layer, a light-emitting layer, an electron There is a three-layer structure composed of a transport layer. Furthermore, it is possible to form a multilayer, and each layer is sequentially formed on the substrate.
[0016]
Examples of hole transport materials include metal phthalocyanines such as copper phthalocyanine and tetra (t-butyl) copper phthalocyanine and metal-free phthalocyanines, quinacridone compounds, 1,1-bis (4-di-p-tolylaminophenyl) Cyclohexane, N, N′-diphenyl-N, N′-bis (3-methylphenyl) -1,1′-biphenyl-4,4′-diamine, N, N′-di (1-naphthyl) -N, Low molecular materials such as aromatic amines such as N′-diphenyl-1,1′-biphenyl-4,4′-diamine, polymer materials such as polythiophene and polyaniline, polythiophene oligomer materials, and other existing hole transport materials You can choose from.
[0017]
Examples of the light-emitting material include 9,10-diarylanthracene derivatives, pyrene, coronene, perylene, rubrene, 1,1,4,4-tetraphenylbutadiene, tris (8-quinolinolato) aluminum complex, tris (4-methyl- 8-quinolinolato) aluminum complex, bis (8-quinolinolato) zinc complex, tris (4-methyl-5-trifluoromethyl-8-quinolinolato) aluminum complex, tris (4-methyl-5-cyano-8-quinolinolato) aluminum Complex, bis (2-methyl-5-trifluoromethyl-8-quinolinolato) [4- (4-cyanophenyl) phenolate] aluminum complex, bis (2-methyl-5-cyano-8-quinolinolato) [4- ( 4-cyanophenyl) phenolate] aluminum complex, Lis (8-quinolinolato) scandium complex, bis [8- (para-tosyl) aminoquinoline] zinc complex and cadmium complex, 1,2,3,4-tetraphenylcyclopentadiene, pentaphenylcyclopentadiene, poly-2,5 -Diheptyloxy-para-phenylene vinylene, coumarin phosphor, perylene phosphor, pyran phosphor, anthrone phosphor, porphyrin phosphor, quinacridone phosphor, N, N'-dialkyl-substituted quinacridone phosphor , Naphthalimide-based phosphors, N, N′-diaryl-substituted pyrrolopyrrole-based phosphors, polymer materials such as polyfluorene, polyparaphenylene vinylene, polythiophene, and other existing light-emitting materials Can do.
[0018]
Examples of the electron transport material include 2- (4-bifinylyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole, 2,5-bis (1-naphthyl) -1, Examples include 3,4-oxadiazole, oxadiazole derivatives, bis (10-hydroxybenzo [h] quinolinolato) beryllium complexes, and triazole compounds.
[0019]
As a method for forming the light emitting medium layer 3, in the case of a low molecular material, the film can be wound and formed by a vacuum deposition method such as a resistance heating method. In the case of a polymer material, the film can be formed by winding using a wet coating method such as flexography, gravure, microgravure, gravure offset, die coating, intaglio offset, or roll coating. The thickness of the light emitting medium layer is 1000 nm or less, preferably 50 to 150 nm, even when formed by a single layer or a stacked layer.
[0020]
Next, the cathode layer 4 is formed on the luminescent medium layer 3. As the material of the cathode layer 4, a substance having a high electron injection efficiency is used. Specifically, a single metal such as Mg, Al, or Yb is used, or a compound such as Li, oxidized Li, or LiF is sandwiched by about 1 nm at the interface in contact with the light emitting medium layer, and Al or Cu having high stability and conductivity is placed. Laminated and used.
[0021]
Alternatively, in order to achieve both electron injection efficiency and stability, one or more metals such as Li, Mg, Ca, Sr, La, Ce, Er, Eu, Sc, Y, and Yb having a low work function and stable Ag, Al An alloy system with a metal element such as Cu or Cu is used. Specifically, alloys such as MgAg, AlLi, and CuLi can be used.
[0022]
As a method for forming the cathode layer 4, depending on the material, it is possible to form a wound film using a resistance heating vapor deposition method, an electron beam vapor deposition method, a reactive vapor deposition method, an ion plating method, a sputtering method, or the like. . It is also possible to laminate a metal foil such as an aluminum foil with the light-emitting medium layer 3 produced on the plastic substrate 1 and laminating both by passing between the rolls and thermocompression bonding. The thickness of the cathode in the case of winding film formation is desirably about 10 nm to 1000 nm. The thickness in the case of laminating the metal foil is preferably 5 μm or more, which is easy to handle, and more preferably 15 μm or more in order to prevent pinholes in the foil. In order to make handling easier, a plastic film such as polyethylene terephthalate may be laminated on the metal foil in advance on the surface opposite to the surface in contact with the EL element.
[0023]
Next, an anode extraction electrode 6a and a cathode extraction electrode 6b for feeding EL elements are formed on the glass substrate 5 (the surface in contact with the plastic substrate). The material of the extraction electrode is a metal material such as aluminum, copper, silver, nickel, chromium, or an alloy material containing one or more of these metal materials, indium tin composite oxide, indium zinc composite oxide, zinc aluminum composite oxide. Metal oxides such as products can be used alone or in combination. Further, a color filter may be formed on the glass substrate 5 and used as a color filter having an extraction electrode.
[0024]
As a method of forming the extraction electrodes 6a and 6b, a resistance heating vapor deposition method, an electron beam vapor deposition method, a reactive vapor deposition method, an ion plating method, a sputtering method, or the like can be used depending on the material. Further, it is preferable to perform masking at the time of film formation, or to process the film into a predetermined pattern using a photolithography etching method or a dry etching method after the film formation.
[0025]
Next, the glass substrate 5 on which the extraction electrodes 6 a and 6 b are formed is laminated on the plastic substrate 1, and the anode extraction electrode 6 a and the cathode extraction electrode 6 b on the glass substrate are connected to the anode of the EL element via the conductive material 7. They are electrically connected to the extraction electrode 2a and the cathode extraction electrode 2b, respectively. At this time, the glass substrate 5 and the plastic substrate 1 are bonded and fixed simultaneously with the electrical connection by the conductive material 7. In order to bond and fix more firmly, it is reinforced by applying UV curable adhesive resin, electron beam curable adhesive resin, etc. between the glass substrate and the plastic base material or between the edges and curing. May be.
[0026]
As the conductive material 7, conductive fine particles such as metal fine particles such as Au, Ag, Cu, Al, and Ni, oxide fine particles such as SnO ₂ and In ₂ O ₃ , carbon fine particles, and polyester resin, acrylic resin, modified Conductive resin materials mainly composed of a binder resin such as urethane resin and epoxy resin, metal materials such as aluminum, copper, and silver, alloy materials composed of tin, lead, silver, etc., SnO ₂ , In ₂ O metal oxides such as _3, and the like alone or in combination may be used. In particular, it is desirable to use at least a conductive resin material that can easily bond and fix the film base and the glass substrate and can be molded at a low temperature.
[0027]
As a method for forming the conductive material 7, a coating method such as a nozzle discharge method or a screen printing method, a film forming method such as a vapor deposition method or a sputtering method, a thermocompression bonding method, soldering, or the like is used depending on the material. be able to. For example, in the case of a paste-like conductive resin material, it can be formed by a screen printing method or the like. In the case of a film electrode made of a metal material, it can be bonded by thermocompression bonding via a film-like conductive resin material.
[0028]
Finally, in order to block moisture from the outside and suppress deterioration of the EL element over a long period of time, the EL element is covered and sealed by thermocompression bonding the moisture resistant film 8. When thermocompression bonding, the end of the moisture-resistant film may be thermocompression bonded, or the entire moisture-resistant film may be thermocompression bonded by passing between heat rolls.
[0029]
The moisture resistant film 8 needs to have at least a barrier layer and a sealant layer. As a barrier layer, a metal oxide such as silicon oxide, aluminum oxide, chromium oxide and magnesium oxide, a metal fluoride such as aluminum fluoride and magnesium fluoride, a metal nitride such as silicon nitride, aluminum nitride and chromium nitride A single layer or laminated film, a film on which aluminum, copper, nickel, stainless steel, an aluminum alloy, or the like is deposited, or a metal foil or alloy foil of these materials can be used. In particular, it is preferable to use a metal foil or an alloy foil having excellent gas barrier properties. In order to facilitate handling during production, a film such as polyethylene terephthalate or nylon may be laminated as a base material.
[0030]
The sealant layer includes polyethylene, polypropylene, acid modified products of polyolefins such as ethylene / propylene copolymers, acid modified products of ethylene / vinyl acetate copolymers, ethylene / acrylic acid copolymers, ethylene / methacrylic acid copolymers. A thermoplastic adhesive resin such as an ionomer can be used.
[0031]
The place where the moisture resistant film 8 is thermocompression bonded is preferably performed with the glass substrate 5 rather than the plastic substrate 1. The reason for this is that when thermocompression bonding is applied to the plastic substrate 1, moisture enters from the end of the plastic substrate 1 and the element deteriorates, and the adhesive strength with the glass substrate is stronger than the plastic substrate. And the film strength of the transparent anode layer formed on the plastic substrate is weaker than that of the glass substrate.
[0032]
【Example】
Hereinafter, an EL element and a manufacturing method thereof according to the present invention will be described. FIG. 1 is a cross-sectional explanatory view of an EL element of the present invention. FIG. 2 is a cross-sectional explanatory view of an EL element of a comparative example.
[0033]
[Example 1]
First, a polyethylene terephthalate film (100 μm) was used as the plastic substrate 1, and an ITO film (150 nm) was wound up as the transparent anode layer 2 by sputtering to form a film (see FIG. 1A).
[0034]
Next, using a photolithography method and a wet etching method, the transparent anode layer 2 was patterned while winding the film to form a transparent anode layer 2 that also served as the anode lead electrode 2a and a cathode lead electrode 2b (FIG. 1). (See (a)).
[0035]
Next, poly [2-methoxy-5- (2′-ethyl-hexyloxy) -1,4-phenylenevinylene] (MEHPPV) is used as the light-emitting medium layer 3, and a film having a thickness of 100 nm is formed by a direct gravure method while winding the film. A coating film was formed. Next, as the cathode layer 4, MgAg was wound up by 200 nm by binary co-evaporation (see FIG. 1B).
[0036]
Next, after forming an ITO film (150 nm) on the glass substrate 5 by sputtering, the ITO film is patterned by using a photolithography method and a wet etching method to form an anode lead electrode 6a and a cathode lead electrode 6b. (See FIG. 1 (c)).
[0037]
Next, the glass substrate 5 and the plastic substrate 1 were laminated. Next, the anode extraction electrode 6a formed on the glass substrate is electrically connected to the anode extraction electrode 2a of the EL element, and the cathode extraction electrode 6b formed on the glass substrate is electrically connected to the cathode extraction electrode 2b of the EL element. Then, a conductive resin material 7 (3320D manufactured by ThreeBond Co., Ltd.) made of a modified urethane resin and silver fine particles was formed to 200 μm by screen printing, and at the same time, the plastic substrate 1 was adhered and fixed to the glass substrate 5. (See FIG. 1 (c)).
[0038]
Next, as the moisture resistant film 8, a polyethylene terephthalate (20 μm), an aluminum foil (20 μm), and an acid-modified product of polypropylene (30 μm) were sequentially dry laminated and extrusion laminated. Next, the EL element was covered with a moisture resistant film in a dry nitrogen atmosphere, and the end of the moisture resistant film was sealed by thermocompression bonding with the glass substrate 1 (see FIG. 1D). The obtained EL element was stored in a constant temperature bath at 40 ° C. and 90% RH for 1000 hours. As a result, the light emitting area was 90% of the initial area.
[0039]
[Example 2]
The EL element was covered and sealed with a glass substrate and a moisture-resistant film in the same process as in Example 1 except that the light emitting medium layer 3 in Example 1 was changed to a low molecular material. Low molecular weight materials include copper phthalocyanine, N, N′-di (1-naphthyl) -N, N′-diphenyl-1,1′-biphenyl-4,4′-diamine, tris (8-quinolinolato) aluminum complex Were sequentially formed by vacuum deposition with a film thickness of 10 nm, 40 nm, and 50 nm. The obtained EL element was stored in a constant temperature bath at 40 ° C. and 90% RH for 1000 hours. As a result, the light emitting area was 90% of the initial area.
[0040]
[Comparative Example 1]
The EL element was covered and sealed by thermocompression bonding of the polyethylene terephthalate film 1 and the moisture resistant film 8 without bonding the glass substrate used in Example 1 (see FIG. 2). As a result of storing the obtained EL element in a constant temperature bath at 40 ° C. and 90% RH for 1000 hours, the EL element stopped emitting light.
[0041]
【The invention's effect】
According to the first aspect of the present invention, at least a transparent anode layer, a light emitting medium layer, and a cathode layer are sequentially laminated on one surface of a plastic substrate, and the laminate is covered and sealed with a moisture-resistant film. In a luminescence element, a glass substrate is laminated on the other surface of the plastic base material to block moisture from the outside, suppress deterioration of the EL element over a long period of time, and provide a thin and lightweight EL element can do.
[0042]
According to the invention described in claim 2, since the EL element can be supplied with electric power from the take-out electrode on the glass substrate having excellent film strength as compared with the transparent anode layer on the plastic film, the invention according to claim 1 is implemented. It is preferable as a form.
[0043]
According to the invention described in claim 3, it is preferable as an embodiment of the invention described in claims 1 to 3 because it prevents moisture from entering from the end of the plastic film and provides sufficient adhesive strength.
[0044]
According to the invention described in claim 4, since the EL element described in claim 1 can be manufactured at low cost, it is preferable as an embodiment of the invention described in claim 1.
[0045]
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing an example of a cross-sectional structure of an EL element of the present invention.
FIG. 2 is an explanatory diagram showing an example of a cross-sectional structure of an EL element of a comparative example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Plastic base material 2 Transparent anode layer 2a Anode extraction electrode 2b Cathode extraction electrode 3 Luminescent medium layer 4 Cathode layer 5 Glass substrate 6a Anode extraction electrode 6b on a glass substrate Cathode extraction electrode 7 on a glass substrate 7 Conductive material 8 Moisture resistant film

Claims (2)

In the electroluminescence device in which at least a transparent anode layer, a light emitting medium layer, and a cathode layer are sequentially laminated on one surface of a plastic substrate, and the laminate is covered and sealed with a moisture-resistant film, the other of the plastic substrate A glass substrate is laminated on the surface, and the moisture-resistant film is thermocompression bonded to the glass substrate .   A step of sequentially laminating at least a transparent anode layer, a light emitting medium layer, and a cathode layer on one surface of the plastic substrate, a step of forming an extraction electrode on the glass substrate, and a layer of the glass substrate on the other surface of the plastic substrate And a step of electrically connecting the extraction electrode to the transparent anode layer and the cathode layer, and a step of covering and sealing the glass substrate on which the extraction electrode is formed and a moisture-resistant film by thermocompression bonding. A method for manufacturing an electroluminescent element.

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