JPH0314540A - EL element - Google Patents

Abstract

PURPOSE:To obtain an EL element of high color purity by using a fluorescent substance emitting bluish green light in the EL element in which a fluorescent layer is placed between the transparent insulated electrode and the opposite electrode and a film colored with a dye emitting complementary color fluorescence to the flnorescent layer is overlaid on the fluorescent layer. CONSTITUTION:In an EL element which has at least fluorescent layer 6 between the transparent and insulated electrode 7 and the opposite electrode 4, the fluorescent body emits bluish green light and the body is laminated with a film which is colored with a dye of the complementary color to the emission of the fluorescent body. For example, if a fluorescent body emitting bluish green, which is obtained by adding copper to zinc sulfide, is used, the film is suitably colored with a fluorescent dye having the maximum absorption at 450 to 550nm. This method gives white light of high color purity and the film on the transparent electrode layer 7 is colored by a simple method to give an EL element which has high stability with the passage of time.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention involves sandwiching a phosphor-emitting layer and a dielectric layer between a pair of electrodes, and applying a voltage between the two electrodes to emit fluorescence. The present invention relates to an electroluminescent display element9, and more specifically, the present invention relates to an electroluminescent display element that emits white light.

(Prior Art) Electroluminescent display elements (hereinafter abbreviated as EL elements) are being applied to various devices as display panels or display light sources, and their practical use is rapidly progressing. E
When using an L element in Babkrite, it is desirable to emit white light, but since there is no phosphor that can emit white light by itself, various studies have been conducted on EL elements that emit white light. being done. A method using a mixture of various phosphors or a mixture of a phosphor and a fluorescent dye has been proposed.

However, in these methods, since the luminescent material is made of a mixture of different types of fluorophores, there is a difference in the lifespan of each fluorophore, it is difficult to stabilize the color tone over a long period of time, and the luminance is insufficient. There was a problem.

(Problems to be Solved by the Invention) The present invention provides an EL element that does not have the above-mentioned drawbacks, has good color purity, and can stably obtain high-intensity white light.

(Means for Solving the Problems) The present invention provides an EL element having at least a phosphor layer between a transparent insulated electrode and a counter electrode, in which the phosphor emits blue-green light, and The gist of the device is a different EL device in which a film colored with a dye that emits complementary color fluorescence is provided on a phosphor layer.

Hereinafter, the EL device of the present invention will be described in detail by citing one example.

Figure / is a schematic diagram showing the structure of an EL element, / is a moisture-proof protective film made of trifluorochloroethylene film or a film laminated with polyethylene 7 film, and λ is a moisture-proof protective film. A back lead electrode, 3 a front lead electrode, and 3 a back electrode layer, usually made of aluminum foil or a plate. The second layer is a dielectric layer, typically formed from a dielectric material such as barium titanate or titanium oxide dispersed in an organic binder such as cyanoethylated cellulose. Reference numeral 6 is a phosphor layer in which a phosphor prepared by adding an activator such as copper to zinc sulfide is dispersed in an organic binder such as polyvinyl alcohol or cyanoethylated cellulose.

Reference numeral 7 denotes a transparent electrode made of aluminum or I.P. on a transparent insulating film such as a polyester film or a nylon film. T
．． O. (composed of indium oxide and tin oxide) etc.

In the present invention, a transparent film colored with a dye that emits light in a complementary color to the color emitted by the phosphor is laminated on the upper surface of the phosphor layer. By coloring with a dye that emits light in a complementary color to the color of the emitted light, it is possible to emit apparently white light when a voltage is applied, or it is also possible to stack a colored film on a transparent electrode film.

For example, blue-green (4
When using a phosphor that emits at tOθ~600 nm), the film placed on the phosphor layer should
- a fluorescent dye having a maximum absorption wavelength in the evening θnm, such as C
．． I. sorbet/thioxa
It is better to use one colored with nthene). For example, in the case of a polyester film, the film can be colored in the following manner.

Sokuchi, C, ■-Solvent Orange-630. /f was added to 200-℃ ethylene glycol, /J-j℃
The temperature rises to A polyester film (OK47K Type #7j manufactured by Diafoil Co., Ltd.) is immersed in this bath for /θ seconds and dyed. The dyed film is washed and dried.

The colored polyester film thus obtained was placed on an EL element having the structure shown in Figure 1, which uses a phosphor (ZnS: Cu) as a light emitting layer, and was energized to emit light, and its surface reflectance was measured. The surface reflection curve shown in FIG. 2 was obtained, confirming the effect of the colored film. In the figure, (a)
(b) represents the surface reflection curve when no colored film is used, and (b) represents the surface reflection curve when a colored film is used.
The vertical axis shows the reflectance (1), and the horizontal axis shows the wavelength (nm).

As a result, the blue-green emission of 3to-4toonm was caused by C.
By coloring with I-Sorpent Orange-63,
It is clear that the reflectance changes and the light approximates the apparent white light.

(Effects of the Invention) According to the present invention, it is possible to obtain white light with good color purity, and by coloring the polyester or nylon film of the transparent electrode layer by a simple method, an EL element structure that is stable over time can be obtained. Obtainable.

[Brief explanation of drawings]

Figure 1 is a schematic diagram showing the structure of an EL element, and Figure λ is a graph of surface reflectance showing the effect of using a colored film. In the figure /: moisture-proof film, 2: rear IJ one electrode,
3: Front lead electrode, y; Back electrode layer, ! = dielectric strength layer, 6: light emitting layer, 7: transparent electrode layer, In Fig. 2, the vertical axis represents reflectance (%) and the horizontal axis represents wavelength (nm).

Claims (1)

[Claims] (1) In an EL element having at least a phosphor layer between a transparent insulated electrode and a counter electrode, the phosphor emits blue-green light and is colored with a dye that emits a complementary color of the emitted light. An EL device characterized by having a film provided on a phosphor layer.