JPH04101390A - Light emitting element - Google Patents

Abstract

PURPOSE:To realize a light emitting element which can be manufactured with high luminance, stability and good reproducibility by installing a first inorganic fluorescent substance layer, a first electric conductor layer, an insulator layer, a second electric conductor layer and a second inorganic fluorescent substance layer in this order, and applying voltage between the first and the second electric conductor layers. CONSTITUTION:On a glass substrate 1, a layer of ZnO:Zn that is the fluorescent substance for a slow electron beam is formed as a first fluorescent substance layer 5 and then, an Al film, as a first electric conductor layer 6, and next, on the surface of Al, a surface oxidized layer is formed as an insulator layer 7, and further, an Au film is formed as a second electric conductor layer 8 and at last, a ZnO:Zn layer, as a second fluorescent substance layer 9. Then, voltage is applied between the first and the second electric conductor layers. It is thereby possible to emit light which is stable, good in reproducibility and high in luminance.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a light emitting device, particularly a light emitting device using MIM and a phosphor, and can be applied to all application fields of light emitting devices such as flat panel displays. be.

[Conventional technology] 2. Description of the Related Art Light emitting elements having an MIM structure are conventionally known.

The second structure is shown in Figure 2. A first metal layer such as A is formed on the substrate, an insulating layer is formed on this surface, and a second metal layer such as Au is further formed on this surface.
Light emission is obtained by applying a voltage between the metal layer and the second metal layer.

However, the emission spectrum of this light-emitting element is 400-1 (
It is a very broad luminescence that shows a range of 10m,
Therefore, this light emitting element could not be used in display devices and the like that require elements of three primary colors with high brightness. Japanese Patent Laid-Open No. 63-232295 is a method for solving these problems. According to this, as shown in Figure 1 of the publication, by inserting a phosphor layer between the second electrode and the insulator layer, a specific wavelength determined by the phosphor is emitted, and at the same time, the insulator layer It is said that the electrons tunneled through the rays can also be directly excited, producing strong light emission.

However, in this configuration, the thickness of the formed insulator layer is 20
-30 Since it is extremely thin, damage during formation of the phosphor layer cannot be ignored, resulting in problems with the stability and reproducibility of the device. In addition, the thickness of the phosphor layer is very thin, only 10-20 mm.
In order to obtain sufficient characteristics as a phosphor, the particle size must be several μm.
Considering that it is necessary, it can be predicted that sufficient emission intensity cannot be obtained with this film thickness. Furthermore, when considering excitation by tunneled electrons, the energy of the electrons is determined by the applied voltage; on the other hand, the energy of tunneled electrons is several eV.
Therefore, it may not emit light depending on the characteristics of the phosphor material used.

[Problems to be Solved by the Invention] An object of the present invention is to provide a light-emitting element that has high luminance, is stable, and can be manufactured with good reproducibility.

[Means for Solving the Problems] The structure of the present invention for solving the above problems is a light emitting device as described in the claims.

FIG. 1 shows the structure of a device according to the present invention. In the present invention, by forming the phosphor layer in the position shown in the figure, damage to the insulator layer, which was a drawback of the conventional technology, can be avoided, and a stable and reproducible device can be realized. Emission intensity also improves. In addition, by combining the phosphor layers, it is possible to create a multicolor light-emitting device by controlling the voltage by additively mixing the emitted light colors of each phosphor and adjusting the emission intensity of each phosphor by applying voltage. .

Regarding the excitation of the phosphor, there are two possible ways: excitation by light emission from the MIM element and excitation by tunnel electrons.
In order to excite each phosphor layer with tunneling electrons, it is necessary that the insulator layer and the first and second conductor layers are each very thin.

Furthermore, each layer must also have translucency.

There are no particular restrictions on the inorganic material phosphor, but considering that when excited by tunneling electrons, the energy of the tunneled electrons is about several eV, the material for the phosphor layer is a fluorophore for slow electron beams. body is desirable. Further, when each phosphor layer is excited by light emitted from the MIM element, it is desirable that the excitation wavelength of each phosphor is 400 nm or less.

Further, as a method for producing the second phosphor layer, it is desirable that damage to the underlying layer is small, and therefore a coating method, vacuum evaporation, or CVD method is desirable.

There are no particular restrictions on the organic material phosphor, and it is desirable that it be a phosphor that can be used as a material for a light-emitting layer of organic thin film electroluminescence.

There are no particular restrictions on the method for producing the first phosphor layer, but a method that causes little damage to the organic phosphor material itself is desirable. That is, a vapor deposition method, an LB method, or a coating method is preferable.

Further, as a method for producing the second phosphor layer, it is desirable that damage to the underlying layer is small, and therefore a coating method or a vacuum evaporation method is preferable.

There are no particular restrictions on the substrate, but if the direction in which light is extracted is from the substrate side, it must be translucent. In that case, the first phosphor layer also needs to have translucency.

[Example code] Hereinafter, the present invention will be specifically explained with reference to Examples.

Example 1 Here, a light emitting device having a device structure as shown in FIG. 1 was manufactured. As the substrate 1, a glass substrate was used. ZnO:Zn, which is a phosphor material for low-speed electron beams, was formed as a first phosphor layer 5 on the substrate by a coating method. Next, an Al thin film having a thickness of about 100λ was formed as the first conductor layer 6 by resistance wire heating. Next, as the insulator layer 7, heating was performed in air at about 150 to 200° C. for 40 minutes to form a surface oxide layer of about 30 to 50 λ on the surface of A1. Furthermore, an Au thin film was formed as a second conductive layer 8 at a thickness of about 100× by resistance wire heating. Finally, as the second phosphor layer 9,
ZnO:Zn was formed in the same manner as the first phosphor layer 5.

In this example, ZnO:Zn was used as the material of the phosphor.
However, similar results were obtained using other phosphor materials for slow electron beams.

Example 2 Here, an element having a structure similar to that of the element manufactured in Example] was manufactured. However, the phosphor layers 5 and 9 contain 2Sr0.0.84P whose excitation wavelength is around 420 nm or less.
2 05・0. IEiB203: Eu2+ was formed using a coating method.

Note that the materials and manufacturing methods of other layers are the same as in Example 1.

The device fabricated in this way provides good 2SrOe
O,84P 205・O,16B 203: Eu
``I got the luminescence of a phosphor.

In this example, 2SrO" 0 is used as the material of the phosphor.
．． 84P 2 05 ・O, 16B 2 03:Eu
Similar results were obtained using phosphor materials shown for 2+ or other excitation wavelengths below 400 nm.

Example 3 Z of the first and second phosphor layers 5 and 9 in Example 1
nO: Instead of Zn, an organic phosphor material having the structure shown below was formed by vapor deposition, and as a method for forming the insulator layer 7, the first conductor layer 6 was left in the air for 10 days. A light emitting device was manufactured under the same conditions as in Example 1, except that a surface natural oxidation layer with a thickness of about 50 Å or less was formed.

H3 An alternating current voltage was applied to each conductive layer of the device thus produced. As a result, luminescence unique to organic phosphor materials was obtained.

Note that the effects of the present invention are not limited to the organic phosphor material used in this example, but similar effects were obtained with other organic phosphor materials.

[Effects of the Invention] As described above, the light emitting element of the present invention is stable, has good reproducibility, and can emit light with high brightness.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing the structure of a light-emitting element of the present invention, and FIG. 2 is a schematic cross-sectional view showing the structure of a light-emitting element having a conventional MIM structure.

Claims (2)

[Claims] (1) A first inorganic material phosphor layer is provided on the substrate, a first conductor layer is formed on the surface of the first conductor layer, and a second insulator layer is formed on the surface of the insulator layer. further has a second inorganic material phosphor layer on the surface thereof, and has a second inorganic material phosphor layer on the surface thereof;
1. A light-emitting device characterized by having a configuration in which a voltage is applied between a conductive layer and a second conductive layer. (2) The light emitting device according to claim (1), characterized in that the first and second inorganic material phosphor layers are replaced by first and second organic material phosphor layers, respectively.