JPH046276B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thin film electroluminescent device that emits electroluminescence in response to an applied voltage.

Conventionally, the structure of thin-film electroluminescent devices (hereinafter referred to as EL devices) consists of a three-layer structure in which a light-emitting layer that emits light in response to an applied voltage is coated with insulating layers on both sides, and is sandwiched between a pair of electrodes. be. However, if the light-emitting pattern of the formed EL element is large and the light-emitting layer undergoes dielectric breakdown due to the applied voltage,
The breakdown tends to spread around the area where this dielectric breakdown occurred, changing the light emission pattern. Therefore, in order to prevent dielectric breakdown, it is conceivable to use a method of increasing the thickness of the entire insulating layer to increase the withstand voltage to prevent dielectric breakdown.
However, in this case, the brightness of the emitted light decreases, so the applied voltage has to be increased, resulting in dielectric breakdown and increasing power consumption.

In view of the above-mentioned problems, the present invention reduces the intensity of the electric field applied to the light-emitting layer with an insulator placed between a pair of flat electrodes to separate the light-emitting layer that emits light in response to the application of voltage. This prevents the expansion of dielectric breakdown over a wide range of the light-emitting pattern of the light-emitting layer, making it highly reliable as a light-emitting display means.
The purpose is to provide devices.

The present invention will be described below with reference to embodiments shown in the drawings. FIG. 1 is a perspective view of a first embodiment of the EL element of the present invention. 1 is a glass substrate with an EL element formed on one surface, 2 is a transparent electrode formed on the surface of glass substrate 1, 3 is a lower insulating layer using an insulating material such as Y ₂ O ₃ , and 4 is a microscopic A light emitting layer is divided into a plurality of independent small pieces through a dividing space (hereinafter referred to as a micro space), and 5 is an upper part made of the same material as the lower insulating layer 3 laminated on the light emitting layer 4. The insulating layer 6 is an electrode made of Al or the like and paired with the transparent electrode 2, and 7 is a lattice part of the upper insulating layer which is filled in minute intervals in the light emitting layer 4 and thickened in a lattice shape. Note that the insulating layers 3 and 5 are located between the light emitting layer 4 and the pair of electrodes 2 and 6, and are thicker and thinner than those shown in each figure. Further, as can be seen from each figure, the light emitting layer 4 is divided into a plurality of regions by the thick portions of the insulating layers 3 and 5.

Next, the operation of the above configuration will be explained.
When a voltage is applied between the transparent electrode 2 and the electrode 6 of the EL element, the light emitting layer 4 emits light. When any one of the light-emitting layers 4 undergoes dielectric breakdown, the breakdown spreads to the entire small piece of that one light-emitting layer 4. However, there are lattice parts 7 of insulating material between the small pieces of the light emitting layer 4,
Dielectric breakdown is less likely to occur than the light emitting layer 4 of the same thickness. Therefore, even if the dielectric breakdown of the light emitting layer 4 spreads, it is limited to only one small piece. In this way, by making the area of the small pieces of the light emitting layer 4 sufficiently small and subdividing the mesh of the lattice portion 7, even if dielectric breakdown occurs in one place, it is possible to prevent the light emitting pattern from being destroyed over a wide range. Therefore, the reliability of the EL element as a light emitting display means can be improved.

FIGS. 2 and 3 show the method for manufacturing the EL element of the present invention. Transparent electrode 2 and lower insulating layer 3 on glass substrate 1
After forming a layer of ZnS doped with Mn, TbF ₃ , etc., the light-emitting layer 4 is formed by a method such as photo etching.
A minute interval is provided to divide the material into small pieces. Next, the upper insulating layer 5 and the lattice portions 7, which are made thicker and filled in minute intervals in the light emitting layer 4, are formed by using a method such as vapor deposition of an insulator made of the same material as the lower insulating layer 3. It is formed. (shown in FIG. 2) where the light emitting layer 4
Since the upper insulating layer 5 is formed with a uniform thickness by vapor deposition or the like at such minute intervals, a convex portion is formed on the upper part of the light emitting layer 4. This convex portion is then removed by photoetching or the like to make it flat. (As shown in FIG. 3) Then, by forming an electrode 6 made of Al or the like, the structure of the EL element is completed.

Note that there is a second embodiment as shown in FIG. This uses a material with a high dielectric constant such as TiO ₂ , BaTiO ₃ , or Ta ₂ O ₅ for the lower insulating layer 3 and the upper insulating layer 5 , and insulator lattice parts 7 at minute intervals dividing the light emitting layer 4 . This uses materials such as Si ₃ N ₄ , Y ₂ O ₃ , and Al ₂ O ₃ which have a lower dielectric constant than the materials used for the lower insulating layer 3 and the upper insulating layer 5 but have a higher breakdown voltage.

Furthermore, although the lattice portions 7 are all square lattice shapes, there is no particular regulation regarding this shape. Moreover, the setting position of the grid portion is a pair of electrodes, that is, transparent electrode 2.
and the electrode 6; in the first and second embodiments, one or both of the lower insulating layer 3 and the upper insulating layer 5 is omitted, and only the lattice portion of the insulating material and the light emitting layer are present between the electrodes. It is also possible to have a structure that

As described above, according to the present invention, since the light emitting layer is divided into a plurality of parts and an insulator is placed between the divided parts, destruction of the light emitting layer is stopped within each divided light emitting layer, and destruction of the light emitting layer is prevented from occurring in other areas. It is possible to prevent chain propagation of light to the light-emitting layer, improve reliability, and have a great practical effect.

[Brief explanation of drawings]

FIG. 1 is a perspective view of the first embodiment of the present invention;
FIG. 3 is a sectional view showing the method for manufacturing the EL element of the first embodiment, and FIG. 4 is a sectional view of the second embodiment. DESCRIPTION OF SYMBOLS 1...Glass substrate, 2...Transparent electrode, 3...Lower insulating layer, 4...Light emitting layer, 5...Upper insulating layer, 6
...electrode, 7...grid section.

Claims (1)

[Claims] 1. A pair of electrodes, located between the pair of electrodes,
and a light emitting layer divided into a plurality of parts that emit light in response to the application of a voltage, and an insulator disposed between the divisions of each of the divided light emitting layers. Thin film electroluminescent device. 2. The thin film electroluminescent device according to claim 1, wherein an insulating layer is disposed between the pair of electrodes and the light emitting layer. 3. The thin film electroluminescent device according to claim 2, wherein the insulating layer is located on at least one side of the pair of electrodes. 4 Between the divisions of the luminescent layer divided into a plurality of parts〓
The thin film electroluminescent device according to claim 3, wherein the insulator disposed in the insulating layer is made of a material having a lower dielectric constant and a higher breakdown voltage than the insulating layer. sense element. 5. The thin film electroluminescent device according to any one of claims 1 to 4, wherein the pair of electrodes has a flat surface.