JPS58137990A - Electroluminescent light emitting element - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention The present invention relates to electroluminescence, in which a phosphor layer or a phosphor layer and a dielectric layer are sandwiched between a pair of electrodes, and an alternating current voltage is applied between the two electrodes to cause a II phosphor to emit light. This relates to light-emitting cables (hereinafter referred to as EL light-emitting cables), and uses new materials to provide high-brightness and high-quality products.

The phenomenon of emitting light when a voltage is applied to a phosphor made of zinc sulfide (Zn8) or the like and injected with impurities as an activator or activator is known as electroluminescence (EL) and L'C.
In recent years, EL light-emitting elements have attracted attention as an energy-saving light source because they consume less power and generate less heat, and can be made very thin.Also, with the rapid digitalization of devices, display elements are becoming more and more popular. With the diversification of electronic devices, attempts are being made to put EL light-emitting devices into practical use for display purposes.

Next, a conventional EL light emitting device will be explained with reference to the drawings. Figure 1 is a cross-sectional view of the main parts of the EL light emitting cable, (13 is a transparent insulating film made of glass or organic transparent film, (2 is
) is mesh-shaped gold, aluminum or ITO (ITO).
oxides of n and 8n) etc. are vapor-deposited on a transparent insulating film.
Formation L7: Transparent electrode capable of transmitting E L light, (
3) For example, a phosphor powder made by injecting an activator or activator such as copper, manganese, aluminum, chlorine, or bromine into zinc sulfide or zinc selenide (Zn8e) is mixed with an organic substance such as cyanoethylated cellulose or fluorine resin. The phosphor layer (4) consists of a thin film dispersed in a binder, and the phosphor layer (4) is made by dispersing high-voltage powders of sodium oxide or barium titanate in the same organic powder as the phosphor layer (3). Formed into a thin film r: dielectric layer; (5) is a counter electrode made of, for example, an aluminum or gold wire or plate; (6) is a transparent moisture-proof protective film to minimize temperature differences. It is. When an alternating current voltage is applied between the EL light-emitting element having the above-described odor-producing electrode (2) and the opposing electrode (5), the phosphor layer (3) emits light. The larger the applied voltage, the higher the optical brightness, and the higher the power source wave number, the higher the brightness. L
In either case, 41j11 degree luminance is high and the half-life is short.

In other words, the reason why the conventional ML light emitting device has hardly been used until now is that the initial brightness is low, and when the initial brightness is increased by adding a power source, the half-life is short. This is because it becomes shorter.

By the way, the halo layer (3) of the ML light emitting device is composed of the following: @1 a: dielectric constant of the organic binder used in the phosphor layer: 6: dielectric constant of the phosphor powder: V: 11 Volume fraction El of the phosphor powder relative to the total volume of the phosphor layer: Electric field applied to the phosphor layer From the above equation, the higher the dielectric constant a of the organic binder used in the phosphor layer, the more it will be added to the phosphor powder. It can be seen that as the electric field increases, the luminance of light emission also increases.

Organic resin binders that have been widely used in the past include cyanoethylated cellulose <tS; Denkishi 11-13), vinylidene fluoride (Denkishi 7-8), and vinylidene fluoride copolymer (Denkishi 11-13).
7 to 10) and epoxy resins (4 to 5) have been widely used. When L is L1 cyanoethylated cellulose,
Adhesive strength is extremely weak and visibility is poor L (problems arise with adhesion of dielectric layers and phosphor layers. This problem can sometimes be improved by using plasticizers, but plasticizers is chemically unstable and has a tendency to deteriorate the characteristic f of the KLL optical element.

On the other hand, although vinylidene fluoride has a higher dielectric constant than many other organic resins, it still has a lower dielectric constant than cyanoethylated cellulose, and it also has poor adhesive strength and poor workability. A copolymer of vinylidene fluoride with improved properties was used, but it had a lower dielectric constant than cyanoethylated cellulose and therefore had lower luminance than cyanoethylated cellulose. Also,
Epoxy resin has strong adhesive strength but poor visibility (and low dielectric constant, so it was not used much).

In view of the above-mentioned points, the present invention improves the half-life by increasing the initial brightness to moderate the power supply conditions. Therefore, in the present invention, by using cyanoethylated polyvinyl alcohol (dielectric constant 14 to 20) as an organic binder in the phosphor layer, the luminance is higher than that when cyanoethylated cellulose is used, and the adhesive strength and visible It is possible to create EL with rich sexuality.

Hereinafter, one embodiment of the EL device of the present invention will be explained with reference to FIG. First, a transparent conductive film made of indium oxide and tin oxide is deposited by sputtering or vapor deposition on a transparent insulating film (1) made of a polyester sheet with a thickness of 0.1 to form a transparent electrode (2). do. Next, cyanoethylated polyvinyl alcohol is dissolved in a polar solvent such as acetone, metherenalketone, or enal acetoacetate.
A solution with a weight mixing ratio of cyanoethylated polyvinyl alcohol and solvent of 1 = 1 to 1:10 is prepared, and the vehicle and L'C sulfide zinc sulfide phosphor powder injected with copper or aluminum are mixed with cyanoethylated polyvinyl alcohol. L'C heating L so that the weight mixing ratio with L is 1:1 to 1:10.
1. Prepare a phosphor paste by separating and kneading. The phosphor paste Ff: a dry film thickness of 10 to 50μ on the electrode (2)
The phosphor layer (3) is formed by applying it unevenly using a roll coater, printing, spraying, etc. and drying it. On the other hand, using the previously prepared solution (vehicle) of cyanoethylated polyvinyl alcohol and a solvent, Tie or BaTi0. Mix 0.5 to 3 parts by weight of high dielectric constant powder such as 0.5 to 3 parts by weight, thoroughly knead to make L7:II electric paste, and paste the dielectric paste into aluminum foil with lθ~50/Q+s. A dielectric layer (4) is formed on the counter electrode (5) by coating and drying it with a roll coater or printing spray to a dry film thickness of 3 to 20 μm. Layer (3) and dielectric layer (4) were each thoroughly dried to remove residual solvent in a vacuum dryer, and then the phosphor layer (3) and dielectric layer (4) were placed facing each other for 80 to 80 minutes. While heating to 170° C., press at a pressure of 10 −/− to 80 #/aI.

In the case of pressure bonding, it is desirable to use silicone rubber with a thickness of 3 to 10 cm on the back surface of the counter electrode (5) so that it conforms to the surface irregularities of the phosphor layer (3). Finally, a transparent protective film of enalene trifluorochloride (6
) to create a KL light emitting element.

Figure 2 shows the KL light-emitting device of the present invention and the conventional KL light-emitting device using vinylidene trifluoride copolymer as an organic paint at room temperature at 100V.

The results of a continuous load test using a Hz power source are shown. In the figure, (a) the EL light emitting device according to the present invention, and (b) the conventional
It is a graph showing each L light emitting element.

As is clear from the figure, the EL light emitting device according to the present invention has high initial brightness and therefore has excellent life characteristics.

In other examples, a crosslinking agent is added to cyanoethylated polyvinyl alcohol to improve its moisture resistance and heat resistance. As a crosslinking agent, use melamine formaldehyde product name 8X-303 or 8X-325.
A phosphor paste and a dielectric paste were prepared by adding 1 to 20% of C (manufactured by Nippon Kasei Co., Ltd.) to cyanoethylated polyvinyl alcohol and using the same formulation as in the previous example.1. A KL luminous index is prepared by coating, drying, and crimping using a suitable method. The EL light emitting device was also subjected to a continuous load test as in the first embodiment, and the results showed that the initial brightness was high and the life characteristics were excellent.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a main part of a gL light emitting element, and Figure 2 is a graph showing the results of a continuous load test on a conventional hL light emitting device and a KL light emitting device according to the present invention. (11 Transparent insulating film (2) Photoluminescent electrode (3) Fluorescent layer (4) Dielectric layer (5) Counter electrode (6) Moisture-proof protective film

Claims (2)

[Claims] (1) A phosphor layer is provided between a pair of opposing electrodes, at least one of which has a structure that allows light to pass through, or both the phosphor layer and the dielectric layer, or one of which is cyanoethylated polyvinyl. An electroluminescent light-emitting cord characterized by being formed using alcohol as a binder. (2) The electroluminescent light-emitting cord according to claim 1, wherein the binder is cyanoethylated polyvinyl alcohol to which a crosslinking agent is added.