JPH03219593A - Thin film EL 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 [Industrial Application Field] The present invention relates to a thin film EL device (thin film electroluminescent device), and particularly to a thin film EL device including a green light emitting layer.

[Prior art] When realizing full-color display using thin film EL elements, the most promising light-emitting materials are SrS:Ce, SrS:Ce, and blue light emitting materials.
ZnS:Tb is currently being researched in green, and CaS:Eu is being researched in red.

However, when considering the adaptability of materials, the problem is that only the green light-emitting material is different from other materials.

That is, ZnS is an nb-vrb group compound, whereas both Ca5SSrS are navxb group compounds.

CaS:Ce and SrS:Mn are known as green light-emitting materials using IIa-Vlb group compounds, but CaS:Ce has poor color purity and exhibits a yellow-green color, while SrS:Mn has a yellow-green color. Depending on the manufacturing conditions, the color may become yellow-orange, and the problem was that the reproducibility of the color tone was poor.

[Problems to be Solved by the Invention] The present invention aims to improve the color purity of CaS:Ce so that it can be used as a green light-emitting material for full-color display.

[Means for Solving the Problems] The configuration of the present invention for solving the above problems is based on CaS:
This is a thin film EL device having a green light-emitting layer made of Ce activated with Tb.

Although the concentrations of Ce and Tb, which are the luminescent centers, vary depending on the manufacturing conditions, etc., the luminescence of Ce should be the main one. This is because when comparing the brightness of CaS:Ce and CaS:Tb, CaS:Ce is higher. Therefore, the Ce concentration is the optimum value of 0.05 to 0.05.
3 mo1%, and the Tb concentration is suitably 0.1 to 2.0 mo1%.

The light-emitting layer may be produced by any method such as vapor deposition, ion blating, sputtering, or MoCVD.

Further, the present invention relates to the light emitting layer of a thin film EL element, and therefore does not specify the electrode material or the insulating layer material. Of course, the element configuration is not limited either, and may be a double-sided insulating structure in which an insulating layer is provided on the picture side of the light-emitting layer, a one-sided insulating structure in which an insulating layer is provided on one side, or a structure in which no insulating layer is used at all.

First, a specific example of a thin film EL element of the present invention having the above structure is shown in FIG.

As shown in the figure, the thin film EL device of the present invention has a glass substrate 1.
, a transparent electrode 2, a light emitting layer 3, an insulating layer 4, and a back electrode 5.

The glass substrate l is preferably made of a material with low alkaline content, such as borosilicate glass or aluminosilicate glass.

The material of the transparent electrode 2 can be used without any particular restrictions as long as it has a function as a transparent electrode, such as ITO.
ZnO-based materials such as nO:A1 have excellent heat resistance and are suitable as materials for the transparent electrode 2. In the embodiments described below, a ZnO:At thin film having a resistivity of -1O-4ΩCnI produced by RP magnetron sputtering is used as the transparent electrode 2.

The material of insulating layer 4 is 813 N4, BN.

Nitride such as AIN, Ta2 05, S], 02, Y 2
Oxides such as 03, Al2O3, etc. can be used. Further, a ferroelectric material having a crystal structure such as a tungsten bronze structure or a perovskite structure can also be used. Furthermore, the insulating layer 4 may be configured in the form of a film made of a mixture of these materials or a composite film formed by laminating thin films made of different materials.

Further, the insulating layer may have a so-called one-sided insulating structure in which only one of them is used, as shown in FIG. 1, or a so-called direct current type structure in which both are not used.

The material of the back electrode 5 laminated on the insulating layer 4 is A.
Examples include first class metal materials.

Of course, if another EL element structure is further stacked on the back electrode 5, it goes without saying that the back electrode should be a transparent electrode.

The present invention will be specifically described below with reference to Examples.

[Example] Here, a thin film EL device having an MIS structure as shown in FIG. 1 was manufactured.

ZnO:Al was formed on a glass substrate, and then a light emitting layer was formed using an electron beam evaporation method at a substrate temperature of 500°C. At this time, 0.1 m of CeCl3 was added to CaS as a light emitting layer.
o1% added and CeCl3 according to the present invention added at 0.
Two types were prepared, each with 1mol1% and 1.0IIo1% of TbCl3 added. After forming the light emitting layer,
A Y2O3 thin film is formed as an insulating layer by electron beam evaporation,
Finally, an AI thin film was formed as a back electrode.

FIG. 2 shows CIE chromaticity points for each color tone of the thin film EL device thus obtained. For comparison, the chromaticity point of green color currently used in color CRTs is also shown.

As can be seen, the element according to the present invention is superior to the element according to the prior art as a color green color.

Although chloride was used as the luminescent center compound in the present invention, similar results were obtained using fluoride or sulfide.

[Effects of the Invention] As explained above, the thin film EL element of the present invention can be used as a thin film EL device that emits green light with an excellent tone as a multicolor green color.
It is element.

[Brief explanation of drawings]

Figure 1 is a cross-sectional schematic diagram showing the structure of the EL element of the present invention. Figure 2 is an EL element of the present invention (CaS:Ce:Tb), a conventional EL element (CaS:Ce), and the current color CR.
It is a graph showing each chromaticity point of the green thin film EL element used in T. DESCRIPTION OF SYMBOLS 1...Glass substrate, 2...Transparent electrode, 3...Light emitting layer, 4...Insulating layer, 5...Back electrode. O: Chromaticity point of the device according to the present invention: Chromaticity point of the device according to the prior art 12 Chromaticity point of green color currently used in color CRTs

Claims (1)

[Claims] A thin film EL device having a green light-emitting layer made of CaS:Ce activated with Tb.