JPH02242584A - Thin-film el element - Google Patents

Abstract

PURPOSE:To improve productivity by forming both a light-emitting layer and a dielectric layer between two electrodes one of which is rendered transparent and having not less than two kinds of activating agents contained in the light- emitting layer. CONSTITUTION:A transparent electrode 2 is formed on a glass substrate 1, a Ta2O5 thin-film as a first dielectric layer 3 is formed thereon, a light-emitting layer 4 is formed on the layer 3, an Al2O3 thin-film as a second dielectric layer 5 is further formed thereon and ultimately an Al thin-film is formed as a back plate 6. Then, CeCl3 and SmCl3 as activating agents are allowed to be contained in the parent-body material of the light-emitting layer 4 made of a mixed crystal chemical compound consisting of a1 least two kinds out of three kinds of chemical compounds of SrS, CaS and ZnS. This process makes it possible to obtain a white-colored light emitting thin-film EL element being excellent in productivity.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a white light emitting thin film EL device.

BACKGROUND OF THE INVENTION Thin film EL devices are self-luminous devices and thin planar light emitting devices, which are excellent advantages, and their applications are progressing mainly in the field of monochrome display panels. However, only an amber color emitting display panel using ZnS:Mn as the emissive layer material has reached a practical level. Therefore, it is desired to realize a full-color display panel with the aim of creating a display panel with even higher distribution value. Red to achieve full color display.

Possible methods include stacking or arranging thin film EL elements that emit green and blue light in a planar manner.

However, although there are thin-film EL devices that emit high-brightness light for red and green, there are thin-film EL devices that emit high-brightness blue light.
Currently, there are no elements. For this reason, S
A blue-green light emitting thin film EL device using rS:CeCe3 and a red light emitting thin film EL device using CaS:EuCQ3 as the light emitting layer material are stacked or arranged in a planar manner, and a blue filter and a green filter are used to achieve full color display. are trying to realize this.

Problems to be Solved by the Invention However, since the full-color thin film EL elements manufactured by these methods are made of different base materials, the manufacturing process is complicated. Red because of the difference in deterioration.

The problem was that the brightness ratio of green and blue changed with use.

In view of the above problems, the present invention provides a white light emitting thin film EL with excellent productivity by using a light emitting layer with a simple single layer structure.
By providing an element and using a color filter in combination, a full-color display panel is provided.

Means for Solving the Problems The thin film EL device of the present invention has two electrodes, at least one of which is a transparent electrode, a light-emitting layer and at least one dielectric layer between the electrodes, and the light-emitting layer has two types. It is configured with the above activator.

According to the present invention, by using a light-emitting layer with a simple single-layer structure, a white light-emitting thin film EL device with excellent productivity can be realized, and furthermore, by using a color filter in combination, a full-color display panel can be realized.

Embodiment An embodiment of the present invention will be briefly described with reference to the drawings. FIG. 1 shows a cross-sectional structural diagram of a thin film EL device of the present invention.

In FIG. 1, a transparent electrode 2 made of ITO is formed on a glass substrate 1 by a DC sputtering method using an indium-tin mixed crystal oxide (hereinafter referred to as ITO) as a target layer.

Next, on top of this, a Ta205 thin film with a thickness of 0.2 μm was formed as a first dielectric layer 3 by high-frequency magnetron sputtering.
Form about m. After this, CeCe3 and SmCl3 were combined as activators in the SrS powder, and the total amount was 0.2 moi!
% or less, and in addition, to compensate for the loss of sulfur (S) due to re-evaporation during vapor deposition, an excess of sulfur (S) is added. After mixing and molding, a tablet is sintered in a △r atmosphere. A light emitting layer 4 having a thickness of about 1 μm is formed using an electron beam evaporation method as a target. At this time, care should be taken to maintain the glass substrate 1 at about 600° C. during vapor deposition, and to simultaneously evaporate sulfur from another crucible in order to compensate for the re-evaporation loss of sulfur.

After this, from high frequency magneto l-r + non-sputtering method 3,
A & 203 thin film is used as the second dielectric layer 5 with a thickness of 0.2μ.
Form about m.

Finally, an Ae thin film is formed as the back electrode 6 by direct current sputtering to complete a thin III E L element.

The thin film EL device fabricated as described above has a unique 450
Broad emission ranging from nm to 580 nm and Sm(1
Sm from 3” specific 565nm 600nm, 655n
The three peaks near ``m'' are combined to produce paper-colored white light emission. FIG. 2 shows the emission spectrum of the thin film EL device of the present invention, and FIG. 3 shows the CIE chromaticity coordinate points.

In one embodiment of the present invention, SrS was used as the host material for the light emitting layer, but it may also be CaS, ZnS, or a mixed crystal compound thereof.

Further, in one embodiment of the present invention, Ta205 and Ae203 are used as dielectric materials to form a two-layer dielectric layer, but SiC2, Si3N4. B a Ti
Other dielectric materials such as O3 may be used, and these]
Needless to say, it is also possible to use only a dielectric layer.

Effects of the Invention The thin film EL device of the present invention has two electrodes, at least one of which is a transparent electrode, and a light emitting layer and at least one dielectric layer between the electrodes, in which the light emitting layer comprises at least two types of dielectric layers. Having the above activator, that is,
SrS or CaS or ZnS or SrS,
Ce is added as an activator to a base material consisting of a mixed crystal compound consisting of at least two of three types of compounds: CaS and ZnS.
With the structure comprising Ce3 and S m Ce3, a white light-emitting thin film E-L device with excellent productivity can be realized using a light-emitting layer with a simple single-layer structure.Furthermore, by using a color filter in combination, a full-color display panel can be realized. will come true. This effect is significant.

(cormorant

[Brief explanation of drawings]

FIG. 1 is a diagram showing CIE chromaticity coordinate points of a thin film EL device according to an embodiment of the present invention. 1... Glass substrate, 2... Transparent electrode, :
3...First dielectric layer, 4...Light emitting layer,
5... Second dielectric layer, 6... Back electrode.

Claims (2)

[Claims] (1) It has two electrodes, at least one of which is a transparent electrode, and a light-emitting layer and at least one dielectric layer between the electrodes, and the light-emitting layer contains two or more types of activators. Thin film EL element. (2) The host material of the light emitting layer is SrS, CaS or Zn
Claim 1, characterized in that it is made of a mixed crystal compound consisting of any one of S or at least two of the three types of compounds, and contains CeCl_3 and SmCl_3 as activators. The thin film EL device described above.