JPH04334896A - El emission layer - Google Patents

Abstract

PURPOSE:To provide an EL emission layer which can form an emission layer made of phosphor in a thin film shape at good manufacturing efficiency and which is excellent in its mass productivity, luminance and emission life. CONSTITUTION:An EL emission layer provided with an emission layer 6 made of phosphor formed in a thin film between a backside electrode layer 9 made of a metal substrate and a transparent electrode layer 1 through an insulating layer 8 consisting of the oxidation treated layer of the metal substrate.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an EL layer that is easy to manufacture and has excellent brightness and lifetime.

0002

[Prior Art] Conventionally, a thin film type EL device has been used, in which a transparent electrode layer and a light emitting layer made of a phosphor are successively formed into thin films on a glass plate by sputtering or the like, and an insulating layer and a back electrode layer are provided thereon. A thick film type EL light emitting device having a light emitting layer formed by applying a dispersion of phosphor particles on the light emitting layer or a back electrode layer via an insulating layer, and a transparent electrode layer formed by applying a transparent conductive paint. The layers were known.

[0003] However, the thin film type EL light emitting layer has the problem that the transparent electrode layer is easily deteriorated at high temperatures during the formation of the light emitting layer, and the problem that it takes a long time to manufacture and is poor in mass productivity. On the other hand, thick film type EL light emitting layers have problems of poor brightness and light emission life.

0004

SUMMARY OF THE INVENTION An object of the present invention is to obtain an EL light emitting layer that is easy to manufacture and has excellent brightness and light emission life.

[0005]

[Means for Solving the Problems] The present invention provides a phosphor layer formed as a thin film between a back electrode layer made of a metal substrate and a transparent electrode layer with an insulating layer made of an oxidized layer of the metal substrate interposed therebetween. The object of the present invention is to provide an EL light-emitting layer characterized by having a light-emitting layer consisting of:

[0006]

[Function] By using a metal substrate whose surface layer is oxidized to form an insulating layer made of a metal oxide layer for the back electrode,
A light-emitting layer made of a phosphor can be formed into a thin film on the back electrode under high-temperature treatment with high production efficiency and stability, and brightness and luminescence life can be improved.

[0007]

EXAMPLE The EL light emitting layer of the present invention is illustrated in FIGS. 1 to 5. 1 is a transparent electrode layer, 6 is a light emitting layer (thin film type) made of a phosphor formed into a thin film, 8 is an insulating layer made of an oxidized layer of a metal substrate, and 9 is a metal substrate. Note that 2, 4, and 7 are insulating layers, 3 is a light emitting layer (thick film type) containing dispersed phosphor particles, and 5
is a transparent electrode layer.

In the present invention, a suitable metal substrate such as aluminum foil is used for the back electrode layer 9. The thickness of the metal substrate is generally 10 μm to 1 mm,
It is not limited to this. On the side of the metal substrate on which the light emitting layer is provided, the surface layer is oxidized to form an insulating layer 8 made of metal oxide. Formation of such an insulating layer may be performed by an appropriate method such as anodizing treatment under an acid solution such as a sulfuric acid solution or a phosphoric acid solution, or thermal oxidation treatment using a flame or the like. Although the thickness of the insulating layer is arbitrary, it is preferably transparent, and from this point of view, the thickness is generally 10 μm or less, particularly 0.2 to 5 μm.

As illustrated in FIG. 2, an insulating layer 7 is provided as necessary on an insulating layer 8 made of an oxidized layer of a metal substrate. The provision of such an insulating layer 7 is intended to improve brightness and luminous efficiency by increasing the dielectric constant, or to prevent the phosphor from reacting with the insulating layer 8 made of an oxidized layer of the metal substrate when forming the luminescent layer 6. It is effective for

[0010] In forming the insulating layer 7, it is preferable to use a self-healing material. Examples include SiO2, Y2
Examples include O3, Sm2O3, Al2O3, etc. The insulating layer 7 may be formed by an appropriate method such as a sputtering method, an electron beam evaporation method, or a CVD method. Its thickness is generally about 1 to 20 μm. The insulating layer 7 and the oxidized insulating layer 8 are preferably transparent, and from this point of view, it is desirable that the total thickness of both insulating layers is 10 μm or less.

As the light emitting layer, at least a thin film type 6 made of a phosphor formed into a thin film is provided. The thin film type light emitting layer may be formed by an appropriate method such as a sputtering method, an electron beam evaporation method, an MOCVD method, or an ALE method. In the present invention, since a metal substrate having an insulating layer made of an oxidized layer is used, a thin film can be efficiently formed at high temperatures and annealing can be performed.

[0012] Examples of the phosphor forming the light-emitting layer include:
Examples include those activated by adding copper, manganese, aluminum, silver, chlorine, fluorine, bromine, rare earth elements, etc. to zinc sulfide, cadmium sulfide, cadmium zinc sulfide, strontium sulfide, zinc selenide sulfide, etc.

In the present invention, as illustrated in FIGS. 4 and 5, if necessary, a light emitting layer 3 (thick film type) containing dispersed phosphor particles may be provided to form a hybrid type EL light emitting layer. The thick film type light emitting layer can be formed, for example, by a method of adding phosphor particles to a binder and coating the binder. Application may be carried out by any suitable method such as screen printing, casting, doctor blading, or roll coating.

[0014] As the phosphor particles, particles such as those exemplified above, or particles coated with a high dielectric constant film, a moisture shielding film, a fluorescent dye fixing film, etc., are generally used. The average particle diameter of the phosphor particles is preferably 10 μm or more, particularly 15 to 40 μm. The volume occupancy of the phosphor dispersed in the light emitting layer is generally 30 to 80%. Note that the phosphor particles coated with the fluorescent dye-immobilized film mentioned above are designed to be able to control the color tone, but such color tone control can also be achieved by incorporating a fluorescent dye or fluorescent pigment into an appropriate layer. can.

Examples of the binder for dispersing the phosphor particles include cyanoethyl cellulose, cyanoethyl sucrose, cyanoethyl pullulan, cyanoethyl polyvinyl alcohol, polyvinylidene fluoride, polytetrafluoroethylene, polychlorotrifluoroethylene, and tetrafluoroethylene/hexafluoropropylene. Polymers, vinylidene fluoride copolymers, and the like are preferably used. Also preferably used is a high molecular weight sol (Japanese Patent Application Laid-open No. 2-33888) obtained by treating an organometallic compound such as tetraethoxysilane by a sol-gel method. Note that such a binder can also be used for forming an insulating layer, a transparent electrode layer, and the like.

[0016] As the copolymer component with vinylidene fluoride in the vinylidene fluoride copolymer, one such as tetrafluoroethylene, trifluoroethylene, chlorotrifluoroethylene, hexafluoropropylene, etc.
A species or two or more species may be used. In preparing the coating solution, an appropriate organic solvent such as cellosolve acetate, dimethylformamide, or methyl ethyl ketone may be used.

As illustrated in FIGS. 4 and 5, when the light emitting layer has two or more layers, the color of the emitted light can be changed as a combination of different color emitted light. In the example shown in FIG. 5, an insulating layer 4 and a transparent electrode layer 5 are provided between the light-emitting layer 3 and the light-emitting layer 6, so that the voltage applied to each light-emitting layer 3, 6 can be modulated. This allows the color of the emitted light to be controlled. Note that the insulating layer 4 is preferably made of a self-healing material.

The transparent electrode layers 1 and 5 can be formed by applying a transparent conductivity imparting agent such as an oxide of indium or tin directly onto the light emitting layer 6 by a thin film forming method such as a sputtering method, or This can be carried out by a method of adhering a transparent conductive film formed by vapor-depositing a conductivity-imparting agent on the film, or the like. It can also be formed by a method of applying a binder dispersion of a transparent conductivity imparting agent.

A current collecting band made of a coating layer of a resin paste containing conductive powder such as silver powder or carbon is provided on the transparent electrode layer, if necessary. The current collecting band is for suppressing bias in the voltage applied to the transparent electrode layer via the terminal type lead electrode. The current collecting band is usually provided in a band shape on a part of the transparent electrode layer.

In the present invention, as illustrated in FIG. 3, an insulating layer 2 is optionally provided between the transparent electrode layer 1 and the light emitting layer 6 for the purpose of improving brightness and light emitting efficiency by increasing the dielectric constant. provided. Therefore, embodiments of the present invention include forms in which the insulating layers illustrated in FIGS. 2, 3, and 5 are appropriately combined. Note that the insulating layer 2 may be formed by an insulating resin coating method, an insulating film laminating method, or the like. The insulating layer may contain high dielectric constant fine particles such as barium titanate, lead titanate, zirconium titanate, titanium oxide, zinc sulfide, and silicon carbide.

[0021] The EL light-emitting layer of the present invention is generally used in practical use in a form in which the outside is surrounded by a cover layer, although the layer is not limited thereto. A plastic film with low water absorption and moisture permeability is preferably used to form the cover layer. Examples include polyvinylidene chloride, vinyl chloride/vinylidene chloride copolymer, polypropylene, high-density polyethylene, tetrafluoroethylene/hexafluoroethylene copolymer, fluorinated ethylene/propylene copolymer, polyethylene terephthalate, ethylene - Examples include tetrafluoroethylene copolymer, polychlorotrifluoroethylene, and copolymers thereof.

[0022] Also, for the purpose of preventing moisture from entering the light emitting layer,
Usually, a water-trapping layer is provided inside the cover layer as required. For its formation, water-absorbing plastics that are insoluble in water but have the property of absorbing and trapping moisture to swell, and among them, those having a moisture absorption capacity of 5 times or more of their own weight are preferably used. Examples include carboxyl groups, sulfonic groups, phosphoric acid groups, quaternary ammonium salts, amino groups, imino groups, ionizable groups such as pyridium groups, and/or salts thereof and/or hydroxyl groups, ether groups, chain-like or Examples include natural or synthetic hydrophilic and water-insoluble polymers having nonionic hydrophilic groups such as cyclic amide groups and nitrile groups.

Specific examples of water-absorbing plastics include polyacrylamide, a blend polymer of polyacrylamide and polyolefin, a copolymer of acrylic acid or its salt and divinylbenzene, and a copolymer of acrylonitrile, vinyl chloride, and ethylene monomer. Alkaline hydrolyzate of copolymer, alkaline hydrolyzate of copolymer of acrylonitrile, vinylidene chloride, and ethylene monomer, formaldehyde crosslinked product of acrylamide copolymer, acid condensation of polyacrylic acid and polyvinyl alcohol epichlorohydrin crosslinked product of polyvinyl alcohol, formaldehyde crosslinked product of a polymer obtained by hydrolyzing acrylonitrile polymer with alkali, phosphoric acid condensate of polyvinyl alcohol, copolymer of 2-hydroxyethyl methacrylate and ethylene glycol dimethacrylate, Copolymer of 2-methyl-5-vinylpyridine and N,N'-methylenebisacrylamide, copolymer of N,N'-dimethylaminoethyl methacrylate and N,N'-methylenebisacrylamide, N-vinyl -Copolymers of 2-pyrrolidone and ethylene glycol dimethacrylate, cross-linked products of polyoxyethylene by radiation irradiation, starch heating condensates under acidic conditions, saponified products of starch-acrylonitrile graft copolymers, vinyl esters and ester-based monomers. Examples include dried copolymers of saturated carboxylic acids and derivatives thereof, isobutylene-maleic acid copolymers, and the like.

Methods for forming the water-absorbing layer include a method of applying a water-absorbing plastic solution and a method of laminating a film made of water-absorbing plastic. The thickness of the water-trapping layer is generally 20 to 300 μm, but is not limited thereto.

[0025]

Effects of the Invention According to the present invention, since a metal substrate having an oxidized insulating layer is used, a light emitting layer made of a phosphor can be formed into a thin film with high manufacturing efficiency, and is excellent in mass production. An EL light emitting layer with excellent properties can be obtained.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an embodiment.

FIG. 2 is a sectional view of another embodiment.

FIG. 3 is a sectional view of another embodiment.

FIG. 4 is a sectional view of another embodiment.

FIG. 5 is a sectional view of another embodiment.

[Explanation of symbols]

1, 5: Transparent electrode layer 3, 6: Luminescent layer 2, 4, 7: Insulating layer 8: Insulating layer made of an oxidized layer of a metal substrate 9: Back electrode layer made of a metal substrate

Claims (1)

[Claims] 1. A light-emitting layer made of a phosphor formed as a thin film is provided between a back electrode layer made of a metal substrate and a transparent electrode layer, with an insulating layer made of an oxidized layer of the metal substrate interposed therebetween. Characteristic EL light emitting layer.