JPS61267299A - Electric field luminous 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 [Technical Field] The present invention relates to an electroluminescent device.

[Background technology]

Display elements are now being used in a wide range of fields, not just electronic devices. As an example, a non-emissive LCD
There is a (liquid crystal) element. However, as a non-emissive type, there is a problem in that the brightness is not sufficient. Therefore, as an alternative to this, electroluminescent devices are attracting attention as a way to improve this. FIG. 3 shows a cross-section of the basic structure of a conventional electroluminescent device 30. A light emitting layer 35 is provided between a glass substrate 31 having a transparent electrode Fif32 on its surface and a light reflective metal electrode Fii36. Insulating layers 33 and 34 are provided on both sides of the light emitting layer 35, as shown in FIG.

In terms of the manufacturing process, each layer is sequentially formed on the glass substrate from the bottom. When an electric field is applied between the transparent electrode layer 32 and the metal electrode layer 36 by the voltage supplied from the power source 37, the light emitting layer 35 starts emitting light, and the light from the light emitting layer 35 is transmitted to the glass substrate. 31,
As shown by the arrow, it will pass through and come out.

However, this conventional electroluminescent device 3o has the following problems because each layer is formed on the glass substrate 31. That is, the glass substrate 31 has poor thermal conductivity, so the electroluminescent element 3o
The problem is that the heat generated from the heat is not properly dissipated. In particular, when the electroluminescent device 30 becomes a planar light emitting device and becomes larger, the amount of heat generated also increases, and this problem of heat dissipation becomes increasingly serious.

On the other hand, apart from this, there is also an increasing demand for electroluminescent elements having curved shapes. However, processing the glass substrate 31 into a curved surface has problems in terms of both technology and cost. There is also the problem that even after it is completed, it tends to break when handled.

1 [Object of the Invention] In order to solve the above-mentioned problems, it is an object of the present invention to provide an electroluminescent element having a structure that is excellent in heat dissipation effect and suitable for forming a curved surface.

[Disclosure of the invention]

In order to achieve the above object, the present invention provides a light emitting layer that is provided between a metal substrate and a transparent electrode layer, and that the light emitting layer emits light when an electric field is applied between the metal substrate and the transparent electrode layer. The gist is an electroluminescent device designed to

Hereinafter, the present invention will be explained in detail with reference to the drawings. 1st
The figure shows a schematic cross-sectional structure of an embodiment of an electroluminescent device (hereinafter referred to as an EL device) according to the present invention. A thin film light emitting layer 6 is provided between the metal substrate 2 and the transparent electrode layer 5. As shown in FIG. 1, the light emitting layer 6 is sandwiched between both sides of the light emitting layer 6.
A thin insulating layer 3.4 is provided. When an electric field is applied between the metal substrate 2 and the transparent electrode layer 5 by the voltage supplied from the power source 7, the light emitting layer 6 starts emitting light, and the light from the light emitting layer 6 As shown by arrows in the figure, it passes through the transparent electrode layer 5 and comes out.

In this way, the EL element 1 of this embodiment is different from the conventional EL element 1.
Unlike the element, a glass substrate is not used, but a metal substrate 2 is used, and at the same time, light is extracted in the opposite direction from the substrate. Since this metal substrate 2 has a higher thermal conductivity than a glass substrate, the heat dissipation effect of this EL element 1 is much better than that of the conventional one. Therefore, the EL element 1 can be easily made larger. Furthermore, since the metal substrate 2 also serves as an electrode on one side of the EL element 1, the number of manufacturing steps required for the electrodes can be reduced compared to the conventional method.

Even when forming a curved surface, the metal substrate 2 is easier to process into a curved surface than a glass substrate. Even after the EL element 1 is completed, its mechanical strength is much stronger than when manufactured using a glass substrate.

FIG. 2 shows a schematic cross-sectional structure of another embodiment of the EL element according to the present invention. In FIG. 2, the same numbers as in FIG. 1 indicate the same components as in FIG. EL shown in Figure 2
In the element 1, an insulating layer 2a between the metal substrate 2 and the light emitting layer 6
However, it is an insulating film formed on the surface layer portion of the metal substrate 2, and in this point it is different from the EL element 1 shown in FIG. In this way, when the insulating layer 2a is an insulating coating provided directly on the surface of the metal substrate 2, the adhesion between the metal substrate 2 and the insulating layer 2a becomes extremely strong. In this way, the light emitting layer N6, which is laminated on the insulating layer 2a firmly formed on the metal substrate 2, naturally becomes stable. Therefore, the reliability of the EL element 1 is improved.

The insulating film is formed by oxidizing, carbonizing, or nitriding the surface layer of the metal substrate 2.
In the above embodiments, which may be implemented in other ways, insulating layers are provided on both sides of the light emitting layer. However, if necessary, an insulating layer may be provided on only one side, and depending on the type of emissive layer, the emissive layer may not be a thin film or may not have an insulating layer at all. However, an EL element having a structure in which the light-emitting layer is a thin film and a thin insulating layer with a relatively large dielectric constant is provided on both sides of the thin film is simply a planar light-emitting device. Not only is it easy to fabricate into devices, but it also has the characteristics of high brightness and long life.

Next, a specific manufacturing example of the EL element according to the present invention will be explained.

As the metal substrate 2, an AI whose surface is mirror-finished!
(aluminum) substrate is used. This metal substrate 2
An Al2O3 film with a thickness of about 4000 wafers is formed as an insulating layer 3 on the mirror surface of.

This AI! The formation of the 203 film is carried out, for example, under an Ar gas pressure of 3.0% containing 1% 02 gas. The metal substrate 2 is held at a temperature of 250° C. in an atmosphere of 0-2 torr of OX I, and a sputtering method is used. On this insulating layer 3, Z
A target material containing a small amount of Mn (for example, 0.5 wt %) in nS is deposited by sputtering. Then, a ZnS film having a thickness of about 5,000 doped with Mn as an active substance, which forms a luminescent center, is formed on the insulating layer 3 as a luminescent layer 6.

At the stage where the light-emitting layer 6 is formed, an annealing treatment is performed for about 1 hour at a temperature of 600° C. and a vacuum degree of 2×10 −6 torr.

After that, as the insulating layer 4, Y2 with a thickness of about 3000
An O3 film is formed on the light emitting layer 6 by electron beam evaporation. Finally, as a transparent electrode layer 5, ITO (indium tin oxide) with a thickness of about 2000 is formed on this insulating layer 4 by sputtering. In the manner described above, the EL element according to the present invention is manufactured.

As a metal substrate 2, the surface layer portion is forcibly nitrided,
An EL element was manufactured in exactly the same manner as described above, except that an AJ substrate provided with an aluminum nitride film was used and the aluminum nitride film was used as an insulator N3.

Of course, instead of the aluminum nitride film, Aj! 20
Three membranes may be used. Further, as the metal substrate 2, a Ta (tantalum) substrate may be used instead of the Al substrate, and a Ta205 film formed on the surface layer as an insulating layer may be used.

Insulating layers 3 and 4 are l'l! A Si3N4 film or a 5rTi03 film may be used instead of the 203 film or the Y203 film. The light-emitting layer 6 may also contain a rare earth fluoride (for example, TbF3) instead of Mn, thereby producing an EL element that emits light in a color specific to the rare earth metal. A 5n02 film may also be used for the transparent electrode layer 5 instead of the ITO film. Of course, the materials and film thicknesses of each layer are not limited to those exemplified above.

〔Effect of the invention〕

As described in detail above, in the EL element according to the present invention, the light emitting layer is provided between the metal substrate and the transparent electrode, and the light emission of the light emitting layer is caused by applying an electric field between the metal substrate and the transparent electrode. It is configured to be done. This configuration improves the release of heat generated from the EL element, making it easier to increase the size of the EL element. In addition, since the metal substrate also serves as an electrode, which is even less necessary than in the past, the structure is simplified and the number of manufacturing steps is also reduced.

Furthermore, by using this metal substrate, the structure is suitable for curved shapes.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing the structure of one embodiment of the EL element according to the present invention, FIG. 2 is a schematic cross-sectional view showing the structure of another embodiment of the EL element according to the present invention, and FIG. The figure is a schematic cross-sectional view showing the structure of a conventional EL element.

Claims (4)

[Claims] (1) Electroluminescence, in which a light-emitting layer is provided between a metal substrate and a transparent electrode layer, and the light-emitting layer emits light when an electric field is applied between the metal substrate and the transparent electrode layer. element. (2) The electroluminescent device according to claim 1, wherein the light emitting layer is a thin film, and this thin film is provided with insulating layers on both surfaces thereof. (3) The electroluminescent device according to claim 2, wherein the insulating layer between the light emitting layer and the metal substrate is an insulating coating formed on the surface layer portion of the metal substrate. (4) The electroluminescent device according to any one of claims 1 to 3, which is a planar light emitting device.
The electroluminescent device according to claim 4, which has a curved surface shape.