KR940009498B1 - El display device - Google Patents

Abstract

a first insulating layer formed on a transparent substrate; a luminescence layer made of a first buffer layer, first luminescence layer, electron inducing layer, second luminescence layer, and a second buffer layer which are formed on the insulating layer; and a second insulating layer and back plate formed on the luminescence layer.

Description

EL display device

1 is a vertical cross-sectional view of a conventional EL display device.

2 is a vertical sectional view of an electroluminescent display device according to the present invention.

3 is a graph showing impurity concentrations of respective thicknesses of fluorescent layers of the EL display device of the present invention.

* Explanation of symbols for main parts of the drawings

1, 11: transparent substrate 2, 12: transparent electrode

3, 13: first insulating layer 4a: first buffer layer

4b: first light emitting layer 4c: electron inducing layer

4d: second insulating layer 4e: second buffer layer

5, 15: second insulating layer 6, 16: back electrode

14: fluorescent layer

The present invention relates to an electroluminescence (EL) display device and a method of manufacturing the same, and in particular, the doping concentration is varied according to the thickness of the fluorescence layer, thereby increasing the effective energy of the mobile electron of the luminescence phenomenon to obtain an effective luminous efficiency, The dopant and the insulating layer do not meet at the fluorescent layer / insulating layer interface to improve the stability.

In general, CRT, which is widely used as a medium for transmitting image information, can obtain a high-efficiency, high-definition image as a display device. However, due to the disadvantage of having a large volume and weight, the CRT is gradually replaced by a flat display device. Lose.

Accordingly, the flat panel display devices include LCD, PDP, and EL. Since the EL display devices are all solid display devices, they have many advantages over other display devices.

The basic structure of the electroluminescent display device is a transparent electrode 12, a first insulating layer 13, a fluorescent layer 14, a second insulating layer 15 and The back electrodes 16 are stacked in this order.

The transparent electrode 12 and the back electrode 16 are made of ITO and Al, and are line-etched with a suitable line width and have an XY matrix to apply an alternating voltage to both ends of the first insulating layer 13 and the second electrode. The carrier is not injected by the insulating layer 15, and the impurity level or interfacial electrons between the fluorescent layer 14 and both insulating layers are accelerated by the strong electric field. The electrons accelerated as described above move in the ZnS matrix while the electrons in the Mn ions become excited and light is generated when the electrons come back to the ground state to display.

In the electroluminescent display device as described above, the fluorescent layer 14 has a uniform distribution by thickness due to the dopant which is the emission center in ZnS, and when the AC power is applied to both electrodes, electrons in the phosphor according to frequency The light is emitted from both step surfaces of the fluorescent layer 14 as it moves. The light emitting layer used in the thin film electroluminescent display device is mainly composed of a polycrystalline form of a group II-VI compound to control the efficiency of the fluorescent layer depending on the grain size and concentration distribution of impurities.

In addition, the electrons passing through the fluorescent layer collide with the light emitting centers distributed inside the fluorescent layer when the device is driven, and the energy accelerated is significantly reduced. In addition, the collision between the electrons having insufficient energy and the light emitting center is caused by It has no problem that the efficiency of the device is lowered because it does not help at all.

The present invention has been made in order to solve the conventional problems as described above, so that the doping concentration in the fluorescent layer is uniform for each film thickness, thereby preventing degradation of the luminous efficiency of the device and having stability of the display device.

The present invention having the above object will be described in detail according to the accompanying drawings.

As shown in FIG. 2, the transparent electrode 2 and the first insulating layer 3 are sequentially stacked on the transparent substrate 1 to form a film. The substrate has a thickness of 500-1000 Å with ZnS on the first insulating layer 3. The first buffer layer (4a) is formed by EB (Electron Beam) method at 200 ℃, and then the first light emitting layer (4b) to 500-1000Å thickness by doping 1 mol% Mn in ZnS on the first buffer layer (4a) )

An electron induction layer 4c is formed on the first light emitting layer 4b with a thickness of 4000-6000 μs, and the Mn in ZnS is doped to 1 mol% on the electron induction layer 4c to a thickness of 500-1000 μs. The light emitting layer 4d is formed. Then, a second buffer layer 4e is formed on the second light emitting layer 4d at a temperature of 200 ° C. with ZnS in the same thickness as that of the first buffer layer, and then a second insulating layer is formed thereon. 5) and the back electrode 6 are sequentially formed.

The manufacturing process of the first buffer layer 4a, the first light emitting layer 4b, the electron induction layer 4c, the second light emitting layer 4d and the second buffer layer 4e is carried out in the same EB method and vacuum is applied to the film angle. It must remain intact.

3A is an enlarged view of a portion of the first light emitting layer 4b and the second light emitting layer 4d of FIG. 2, and FIG. 3B is a first light emitting layer 4b and a second light emitting layer of FIG. 4d) impurity doping concentration is shown. Referring to the effects of the present invention as described above are as follows.

When AC power of about 200 V is applied between the transparent electrode 2 and the back electrode 6 of the present invention, when the transparent electrode 2 has a cathode, the light emitting layers 4a-4e interface with the first insulating layer 3. The electrons in the are turned and guided to the first buffer layer 4a. The induced electrons collide with the emission center in the first emission layer 4b, but since the electrons do not have enough energy to cause emission, light is hardly generated and the number of free electrons is increased. The electrons thus formed are accelerated while passing through the thickness of the electron induction layer 4c so that the electrons have energy equal to gEd (g: amount of charge, E: intensity of electric field, and d: thickness of the electron induction layer). When it collides with the light emitting center in (4d), when the electron in the valence band of the light emitting center is excited with the conduction band and falls back to the valence band, light is generated as much as the energy difference of the light emitting center. Passing through the second buffer layer 4e, the interface of the second insulating layer 5 is reached. When the transparent electrode 2 becomes the anode, light is emitted from the second light emitting layer 4d while the electrons move in the opposite direction again.

In the present invention, the first buffer layer 4a and the second buffer layer 4e are increased in the crystallization of the first light emitting layer 4b, the second light emitting layer 4d, and the electron induction layer 4c during the light emitting layer deposition process, and the first light emitting layer ( Since the 4b) and the second light emitting layer 4d do not directly contact the first insulating layer 3 and the second insulating layer 5, the fluorescent layer 14 and the insulating layers 13 and 15 come into contact with each other as before. Therefore, it is possible to reduce the decrease in luminance due to the driving time generated.

In addition, since the electroluminescent device of the present invention is driven by an AC power source, the frequency of light emission is changed according to the change of the frequency of the applied power source, and thus the luminance of the entire device is changed.

As described above, the present invention increases the effective energy of mobile electrons participating in the light emitting phenomenon by varying the doping concentration for each film thickness of the light emitting layers 4a, 4b, 4c, 4d, and 4e to obtain an effective light emitting efficiency, and the light emitting layer and the insulating layer interface with each other. It is not possible to meet at, which will increase the stability of the display device.

Claims (3)

A first insulating layer is laminated on the transparent substrate, and the first buffer layer 4a, the first light emitting layer 4b, the electron induction layer 4e, the second light emitting layer 4d, and the second buffer layer 4e are disposed on the first insulating layer. And a second insulating layer (5) and a back electrode (6) stacked on the light emitting layer. The thickness of the first buffer layer is 500-1000 mPa, the thickness of the first light emitting layer is 500-1000 mW, the thickness of the electron induction layer is 4000-6000 mW, and the thickness of the second light emitting layer is 500-1000 mW. And the thickness of the second buffer layer is 500-1000 GPa. The method of claim 1; An electroluminescent display device according to claim 1, wherein the first light emitting layer and the second light emitting layer are doped with 1 mol% of Mn in ZnS.