JPS62133696A - Thin film el display device - 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 [Technical Field of the Invention] The present invention relates to a thin film EL display element with enhanced contrast in light emission.

[Technical Background of the Invention] Generally, a thin film EL display element is a double insulation device in which a transparent electrode, an insulator layer, a light emitter layer, an insulator layer, and a back electrode are sequentially laminated on a transparent substrate such as a glass substrate. structure (hereinafter referred to as MISI structure) and a single insulating structure (hereinafter referred to as MIS structure) in which the insulating layer between the transparent electrode and the light emitting layer is omitted in this MISI structure. be.

In such a film EL display element, transparent materials are usually laminated except for the back electrode Affl, and the method for forming the transparent materials is generally as follows.

That is, an ITO film, which is a transparent electrode material, is formed on the surface of a glass substrate by vacuum evaporation or sputtering, and the ITO film is
The TO film is formed into a predetermined pattern by photolithography (hereinafter referred to as PEP method).

An insulator layer made of metal oxide is applied to this surface, and then, for example, Z
A light emitting layer made of nS:Mn or the like and the insulating layer are sequentially formed to a predetermined thickness by electron beam evaporation or sputtering, respectively.

Thereafter, Afl is deposited by vacuum evaporation or sputtering, and a predetermined pattern as a back electrode is formed by PEP. Also, in the MIS type thin film EL display element, the method for forming the MISI structure is the same as described above except that one of the insulating layers is omitted.

Examples of structures of MIS type thin film EL display elements using such a formation method include JP-A-54-116891 and JP-A-58-21.
6392 and 59-141194 etc.

[Technical background of the invention and its problems] In a thin film EL display element having such a structure, after forming a pattern of a transparent electrode, a two-dimensionally continuous film such as ZnS:
Forming a light emitter layer made of Mn poses the following problems. That is, (1) The light emission phenomenon within the light emitter layer is three-dimensional, and the amount of light that can be taken out to the outside is about 173 of the total amount of light. The remaining 273 amounts of light are lost due to repeated reflections, transmission to the back surface, or absorption during the propagation process in the creeping direction. This state is shown in FIG.

In the figure, reference numeral 1 indicates a transparent substrate such as a glass substrate, on which a transparent electrode 2, an insulator layer 3, a light emitting layer 4, an insulator layer 3, etc.
and a back electrode 5 are sequentially laminated.

As shown in the figure, since the light-emitting layer 4 is a two-dimensional continuous layer, light emission is observed in areas other than the light-emitting area where the transparent electrode 2 and the back electrode 5 face each other, or in non-selected areas. This scattering of light causes a decrease in contrast.

(2) Since the light-emitting layer 4 is provided on the patterned transparent electrode 2, the electric field is concentrated at the electrode end, and dielectric breakdown that penetrates the light-emitting layer 4 is likely to occur.

[Object of the Invention] The present invention has been made in view of the above-mentioned problems, and is directed to a thin film EL display element, particularly an MIS type thin film E, which prevents light scattering in the light emitting layer to improve contrast and withstand voltage.
The present invention aims to provide an L display element.

[Summary of the Invention] The above object of the present invention is to form a transparent electrode formed on a transparent substrate and a light emitter layer formed on the transparent electrode in the same pattern, and also to form grooves of the pattern into a light absorbing layer. This can be achieved by filling it with a certain amount of insulator.

[Embodiment of the Invention] The present invention will be described in detail below with reference to an embodiment shown in the drawings. In addition, in all the drawings, the same parts are denoted by the same reference numerals.

FIG. 1 shows a cross-sectional structure of an embodiment of the present invention.
A transparent electrode 2 made of ITO is formed in a predetermined pattern on a transparent substrate 1 such as a glass substrate, and a light emitting layer 4 made of zns:Mn in the same pattern as the transparent electrode 2 is formed thereon. Furthermore, S! having a value of x such that the optical hand cap is approximately 28V or less is filled in the recessed portion of the pattern. A black insulator layer 6 of C+ is formed on which is formed, for example BaT! 03 or PbTiO
An insulator layer 3 made of a ferroelectric material such as No. 3 and an A° C. electrode, that is, a back electrode 5 are sequentially laminated. Note that point A in Figure 1
Point B in FIG. 3, which shows a cross section of a conventional MIS structure for comparison, indicates the location where the electric field is most concentrated.

In the structure of this embodiment, when the ITO film is formed into a predetermined electrode pattern, the light emitting layer 4 having an insulating property of ZnS:Mn is formed in the same pattern at the same time, so the degree of concentration of the electric field at point A is The reduction is much greater than that at point B in the conventional MIS structure shown in FIG. Also, the first
In the structure shown in the figure, the ZnS:Mn light emitting layer 4 is in a cascade shape, and the grooves between the ITO electrodes are filled with a black insulator 6 of 5ixC+x, so that the selected line does not emit light. It will not leak into the selection line. In particular, in the conventional structure, light propagating in a direction perpendicular to the direction in which the ITO electrodes are arranged is reflected by the high-reflectivity AI back electrode 5 surface, so halation in this direction is large. According to the structure of this example, this was not observed at all, and light scattering was significantly reduced as a whole.

Furthermore, in this example, the applied voltage can be lowered due to the residual polarization of the ferroelectric material used as the insulator layer 3, and since it exhibits a hysteresis phenomenon, a memory function can be expected.

[Effects of the Invention] As is clear from the above description, the thin film EL display element of the present invention can prevent light emission from selected pixels from leaking to non-selected areas, and can obtain high contrast.

In addition, since the transparent electrode and the insulating light emitter layer are integrally formed, the electric field concentration at the end of the pattern can be weakened, and the withstand voltage can be improved.
As a means of lowering the resistance value of the transparent electrode, the film thickness of this electrode can be increased, so it is easy to create a thin film E with a large display capacity.
It becomes possible to realize an L display element.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the structure of an embodiment of the present invention, and FIGS. 2 and 3 are sectional views showing the structure of a conventional thin film EL display element. 1...Transparent substrate 2...Transparent electrode 3...Insulator layer 4...Light emitter layer 5... Back electrode 6... Black insulating layer Applicant Toshiba Corporation Representative Patent attorney Sasu Suyama - Figure 1 Figure 2

Claims (2)

[Claims] (1) In a thin film EL display element in which a transparent electrode, a light emitter layer, an insulator layer, and a back electrode are sequentially laminated on a transparent substrate, the transparent electrode and the light emitter layer are formed in the same pattern. A thin film EL display element characterized by: (2) The concave portion of the pattern is filled with a light-absorbing insulator.
Thin film EL display element as described in .