JP3056894B2 - Electroluminescent light source - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electroluminescent light source which emits light by the action of an electric field.

[0002]

2. Description of the Related Art Electroluminescence (hereinafter abbreviated as EL) has been known as electroluminescence. That is, an electroluminescent layer in which a luminescent center forming material is doped in a base material such as ZnS is interposed between a pair of electrodes, and an electrode is applied so that an electric field of about 10 ⁵ to 10 ⁶ V / cm acts on the electroluminescent layer. By applying a voltage between them, the electroluminescent layer emits light to extract visible light. As the electrode, a transparent electrode film such as a Nesa film or an ITO film is generally used.

On the other hand, an electroluminescent layer, which is obtained by impregnating porous aluminum oxide with an activator such as terbium and heat-treated, is interposed between a pair of electrodes, and emits visible light by applying an AC electric field. as electroluminescent light sources to have been proposed (Kazunari Mizuki like; "reverse electrolysis peeling Tb ³⁺ -activated anodized Al ₂ O ₃ film green light-emitting element using a" surface technology, Vol.40, No. 12,1989). In this configuration, it is considered that a substance constituting the electroluminescent layer emits light by collisional excitation of plasma generated in the porous bore.

[0004]

However, in order to apply a high electric field to the electroluminescent layer as described above, it is necessary to reduce the distance between the electrodes. Since the thickness must be reduced, there is a problem that the volume of the electroluminescent layer is reduced and the amount of light emission is reduced. In addition, in both of the above-described configurations, it is necessary to apply a high electric field to the electroluminescent layer, so that the electroluminescent layer is liable to be deteriorated and has a short life.

An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide an electroluminescent light source having a high luminous efficiency and a long life.

[0006]

According to the present invention, in order to achieve the above object, an electroluminescent layer is interposed between a pair of electrodes,
In an electroluminescent light source that causes an electroluminescent layer to emit light by an electric field between electrodes, the electroluminescent layer includes a porous light-emitting base and a light-emitting substance that is embedded in the space of the light-emitting base and generates electroluminescence by an electric field between the electrodes. The light-emitting base is made of a material that emits visible light when excited by light generated from a light-emitting substance.

[0007]

According to the above construction, the electroluminescent layer is constituted by the porous luminescent base and the luminescent substance which generates electroluminescence by the electric field, and the luminescent substance is embedded in the space of the luminescent base and the luminescent substance is formed. Since the light-emitting base is formed by a material that emits visible light when excited by generated light, by embedding a light-emitting substance that is an excitation source for exciting the light-emitting base in the light-emitting base that is a light-emitting source. In addition, light generated from the excitation source can be efficiently used for exciting the light emission source, and as a result, the light emission efficiency is increased. For example, if a fluorescent substance that emits ultraviolet light by electroluminescence is used as a light emitting substance and a light emitting base is formed by silicon that emits visible light by ultraviolet light, the electric field is used only for emitting ultraviolet light. Most of the generated ultraviolet light is converted to visible light,
Visible light can be emitted with high efficiency. In addition, since the luminescent material is embedded in the luminescent base, the luminescent material is protected, so that deterioration of the luminescent material is reduced.

[0008]

Embodiment 1 (Embodiment 1) In this embodiment, as shown in FIG. 1, a fluorescent substance 1b which emits ultraviolet light by electroluminescence is buried in a light emitting base 1a made of porous silicon, and an electroluminescent layer 1 is formed.
Is formed. The light emitting base 1a is obtained by oxidizing p-type silicon in hydrofluoric acid. The space ( that is, the pore ) formed in the light emitting base 1a is filled with the light emitting substance 1b. In FIG. 1, the distribution density of the light emitting substance 1b is expressed to be different for each place. It is desirable that the luminescent material 1b be distributed almost uniformly in the luminescent base 1a. On one surface of the electroluminescent layer 1 in the thickness direction, a reflective electrode 2a made of an aluminum thin film formed by vapor phase plating (e.g., vapor deposition) is applied, and on the other surface of the electroluminescent layer 1 in the thickness direction, A transparent electrode 2b with an ITO film is applied. Here, both the electrodes 2a and 2b may be transparent electrodes, and an aluminum reflection film may be formed separately from the electrode 2a.

When a voltage is applied between the two electrodes 2a and 2b by the AC power source AC to the electroluminescent light source configured as described above, an electric field acts on the luminescent material 1b of the electroluminescent layer 1 to cause electroluminescence. Ultraviolet light due to the sense is emitted from the luminescent material 1b. In addition, since the light emitting base 1a is present around the entire circumference of the light emitting substance 1b, the ultraviolet light is converted into visible light by the light emitting base 1a, and the visible light is eventually extracted to the outside. . Here, in the porous silicon, tens of angstroms of fine pores are formed innumerably and the surface area is 200 m ² / cm.
^{Since it is} about ^3, the ultraviolet light emitted from the luminescent material 1b is applied to a very large area on the luminescent base 1a, and as a result, is converted to visible light without waste and high efficiency is obtained. . Further, since the surrounding of the luminescent substance 1b is protected by the luminescent base 1a, the luminescent substance 1b
Less deterioration and longer life Moreover, one electrode 2a
Is made of aluminum, the light radiated to the back side can be reflected by the electrode 2a and extracted to the front side, and as a result, high luminous efficiency can be obtained.

(Embodiment 2) In this embodiment, instead of the luminescent material 1b in Embodiment 1, a fluorescent material which emits visible light together with ultraviolet light by electroluminescence is used. That is, the luminescent material 1b is formed by mixing two or more kinds of fluorescent materials. With this configuration,
Since visible light is also emitted from the luminescent material 1b in addition to ultraviolet light, the amount of the luminescent material 1b emitted from the luminescent material 1b and corresponding to ultraviolet light that cannot be converted into visible light by the luminescent base 1a is converted into a visible light fluorescent material. , The amount of emitted visible light is further increased, and as a result, the amount of emitted light is increased. Another configuration is the first embodiment.
The description is omitted here.

Embodiment 3 In this embodiment, as shown in FIG. 2, both electrodes 2a and 2b are formed of aluminum. In this configuration, light emitted from the electroluminescent layer 1 is not extracted in the thickness direction, but can be extracted in a direction orthogonal to the thickness direction. As the electroluminescent layer 1, those of the first or second embodiment can be used. A voltage is applied between the electrodes 2a and 2b by a DC power supply DC. Other configurations are the same as in the first embodiment.

In each of the above embodiments, the electrodes 2a and 2b are directly adhered to both surfaces in the thickness direction of the electroluminescent layer 1. However, in the case of using the AC power supply AC as in the first and second embodiments. In this case, an insulating layer can be interposed between the electrodes 2a and 2b and the electroluminescent layer 2 as is well known in the art.
Further, the material of the light emitting base 1a is not limited to p-type silicon, but may be any porous material that can convert light emitted from the light emitting substance 1b into visible light.

[0013]

According to the present invention, as described above, the electroluminescent layer is
It consists of a porous light-emitting base and a light-emitting substance that generates electroluminescence by an electric field. The light-emitting substance is embedded in the space of the light-emitting base, and is emitted by a material that emits visible light when excited by light generated from the light-emitting substance. Since the base is formed, the light generated from the excitation source is efficiently used to excite the emission source by embedding the luminescent substance that is the excitation source for exciting the luminescence base in the luminescence base that is the luminescence source. Can be used well,
As a result, there is an advantage that luminous efficiency is increased. In addition, since the light emitting substance is embedded in the light emitting base, the light emitting substance is protected, and there is an effect that deterioration of the light emitting substance is reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first embodiment and a second embodiment.

FIG. 2 is a sectional view showing a third embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electroluminescent layer 1a Light emitting base 1b Light emitting substance 2a Electrode 2b Electrode

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-335624 (JP, A) JP-A-6-163982 (JP, A) JP-A-61-88496 (JP, A) 123097 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H05B 33/00-33/28 H01L 33/00 F21K 2/00 JICST file (JOIS)

Claims (1)

(57) [Claims] 1. An electroluminescent light source in which an electroluminescent layer is interposed between a pair of electrodes and the electroluminescent layer emits light by an electric field between the electrodes, wherein the electroluminescent layer includes a porous luminescent base and a luminescent base. A light-emitting substance which is embedded in the space and generates electroluminescence by an electric field between the electrodes; and a light-emitting base is formed of a material which emits visible light when excited by light generated from the light-emitting substance. Luminescent light source.