JPH05109483A - Double-sided luminescence el element and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide a double-sided luminescence EL element having thin thickness and a simple manufacturing process and its manufacture. CONSTITUTION:A common back electrode layer 1 made of a conductor, insulating layers 2 formed on both opposite faces of the back electrode layer, EL luminescence layers 3 formed on them, and transparent electrodes 4 formed on the EL luminescence layers 3 are provided. The process to form the insulating layers 2 on both opposite surfaces of the conductor 1 and the processes to form the EL luminescence layers 3 and the transparent electrodes 4 on the surfaces are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an EL (electroluminescence) element, and more particularly to a double-sided light emitting EL element having light emitting layers on both sides of a substrate and a method for manufacturing the same.

[0002]

2. Description of the Related Art Various electronic devices in recent years are lightweight, thin,
There is a strong demand for low voltage and low power consumption (battery drive), and for example, the use of flat display devices as display devices is increasing.

There is a strong demand for such a display device to be thin, lightweight and inexpensive. The thick film EL element is a light source that can be made thinner than, for example, a fluorescent lamp or an incandescent lamp, and has low power consumption and is capable of surface emission.

FIG. 4 schematically shows an example of a conventional double-sided emission EL device. A double-sided light emitting EL element is made by bonding two similar single-sided light emitting EL elements back to back and bonding a common electrode to both back surfaces.

In each single-sided light emitting EL element, a resin insulating layer 20 is formed on a back electrode 10 formed of aluminum foil. The resin insulating layer 20 is formed by dissolving a high dielectric constant resin (hereinafter referred to as a binder) in a solvent, dispersing barium titanate powder, forming an ink, and applying the ink on the back electrode 10 by a printing technique or the like, followed by drying. it can.

An EL light emitting layer 3 and a transparent electrode 4 are formed on the insulating layer 20. Similarly, the EL light emitting layer 3 is formed by mixing a binder with a phosphor together with a solvent to form an ink, coating the insulating layer 20 by a printing technique or the like, and drying the ink.

Further, the transparent electrode 4 is also added to the binder by I
It is obtained by dispersing TO (indium tin oxide) powder, dissolving it in a solvent, forming it in the form of an ink on the EL light emitting layer 3, and drying. Alternatively, a transparent electrode film obtained by depositing ITO on a polyester film can be used as the transparent electrode 4.

Further, a common lead electrode 5 and a lead electrode 6 of the transparent electrode 4 are formed from each back electrode 10 and the transparent electrode 4.

Further, the EL element is formed by packaging the element body with a film (not shown) having high moisture resistance.

[0010]

As a double-sided emission EL device that must meet the demand for miniaturization, it is a very important issue to be as thin as possible. The double-sided light emitting EL element according to the conventional technique has a problem that the two single-sided light emitting EL elements are back-to-back and adhered to each other, so that the element becomes thick.

Further, in the conventional technique, since the resin insulating layer is used as the insulating film, there is a problem that the thickness of the insulating layer becomes large.

Further, a step of electrically connecting the two back electrodes and a step of aligning the two single-sided light emitting elements have been required.

An object of the present invention is to provide a double-sided light emitting EL device having a small thickness and a simple manufacturing process, and a manufacturing method thereof.

[0014]

A double-sided light emitting EL device of the present invention comprises a common back electrode layer made of a conductor, an insulating layer formed on each of opposite sides of the back electrode layer, and both insulating layers. EL light-emitting layer formed on each and both EL
A transparent electrode formed on each of the light emitting layers.

The method for manufacturing a dual emission EL device of the present invention comprises:
The method includes a step of forming an insulating layer on each of the opposing surfaces of the conductor, and a step of forming an EL light emitting layer and a transparent electrode on each surface of the both insulating layers.

The conductor preferably comprises aluminum foil,
The insulating layer preferably includes a barrier type aluminum oxide film obtained by anodizing an aluminum foil.

[0017]

By using the opposite surfaces of the conductors as a common back electrode, it is not necessary to stack two back electrodes, and the double-sided EL light emitting device can be made thin as a whole, and the manufacturing process is simplified.

Further, if the insulating layer is formed by anodizing the back electrode containing aluminum foil, the thickness of the insulating layer becomes thin, and the element as a whole can be made thinner.

[0019]

EXAMPLE FIG. 1 schematically shows a dual emission EL device according to an example of the present invention. An insulating layer 2 of an aluminum oxide (Al ₂ O ₃ ) film is formed by anodic oxidation on both surfaces of a common back electrode 1 made of aluminum foil, which face each other.

The insulating layer 2 is formed by anodizing both surfaces of an aluminum foil in a neutral electrolytic solution to form a barrier type aluminum oxide film on the surface.

The barrier type aluminum oxide film is preferably a non-porous dense Al ₂ O ₃ film, and is formed by the following steps, for example.

The prepared aluminum foil was heated to 50 ° C. or higher,
It is preferably immersed in distilled water heated to 90 ° C. or higher.
A hydrated oxide of aluminum having naps is formed on the surface of the aluminum foil immersed in distilled water. In addition,
It will be apparent that other pure water such as ion-exchanged water may be used instead of distilled water.

In distilled water, a concentration of 1 ppm to 100 p
It is also possible to add pm of phosphoric acid or phosphate. Addition of phosphoric acid or phosphate eliminates uneven hydration,
An EL element with high brightness can be formed.

In distilled water, Mn, Eu, Tb, N
It is also possible to add an activator such as a rare earth element such as d or Dy. These activators are uniformly dispersed in the formed film, and as a result, improve the brightness of the EL device.

An aluminum foil having a hydrated oxide formed on its surface is anodized in a neutral aqueous solution of an inorganic or organic acid salt having a pH of 5 to 8 such as an ammonium borate aqueous solution, an ammonium phosphate aqueous solution, an ammonium adipate aqueous solution. Oxidize.

By anodic oxidation, the hydrated oxides are gradually dehydrated, and the amorphous Al ₂ O ₃ on the aluminum foil surface is also removed.
Are transformed into a barrier-type film composed mostly of γ-type and / or γ′-type nonporous and dense crystalline Al ₂ O ₃ .

The hydrated oxide on the surface of the anodic oxide film is effective in improving the wettability with the binder at the time of forming the EL layer, eliminating repellency, and eliminating uneven light emission.

The step of immersing the aluminum foil in distilled water at 50 ° C. or higher is for forming a hydrated oxide as described above, and this hydrated oxide is extremely thin on the surface due to anodic oxidation in the next step. A γ-type and / or γ′-type dense non-porous Al ₂ O ₃ crystalline oxide in which hydrated oxide remains can be prepared.

When the fine pseudo-boehmite crystals are dehydrated, γ- (or γ '-) alumina fine crystals are enclosed in the barrier film grown by anodic oxidation, and the phase transition from amorphous to γ'-alumina occurs. Acts as a nucleus.

Aluminum oxide is an aluminum base
It is formed from both the oxide film interface and the oxide film / electrolyte interface. The formed crystal oxide layer is a dense barrier type, has excellent withstand voltage, has a high capacitance, and is not easily destroyed even when an overvoltage is applied.

During the anodizing step, the voltage applied to the electrolytic solution composed of the neutral aqueous solution is preferably 70 to 300V. The higher the electrolysis voltage is, the better the luminous efficiency is, but if it exceeds 300 V, the hydrated oxide layer almost disappears.
Repelling occurs when the hydrated oxide layer disappears.

If the voltage exceeds 300 V, the crystal oxide layer becomes too thick, and the voltage drop due to the crystal oxide layer causes a decrease in luminous efficiency and brightness.

When the voltage is lower than 70 V, the withstand voltage is extremely lowered, and when a voltage higher than the practical voltage of about 100 V is applied, a short circuit is apt to occur and the EL element cannot sufficiently function.

The current density during anodic oxidation is 0.1-0.1%.
5 A / dm ² , the value of the current drop after the constant voltage shift is 1.0 to 5
A / dm ² is preferred. The temperature of the electrolytic bath is preferably room temperature to 90 ° C. However, these conditions are not restrictive.

The reason for electrolyzing in a neutral electrolytic solution is to form a dense barrier type film. When electrolysis is carried out with an acidic electrolytic solution as in the alumite treatment, the oxide film formed becomes a porous film. By forming a non-porous dense barrier type film, an EL element having excellent withstand voltage and luminous efficiency can be obtained.

An EL light emitting layer 3 and a transparent electrode 4 are formed on each of the two aluminum oxide insulating layers 2. The EL light-emitting device 3 is a high-dielectric-constant organic resin such as cyanoethyl pullulan mixed with a solvent to form an ink, which is applied on the insulating layer 2 by a printing technique or the like and dried. is there.

In addition, the transparent electrode 4 is also added to the binder as I.
It is obtained by dispersing TO (indium tin oxide) powder, dissolving it in a solvent, forming it in the form of an ink on the EL light emitting layer 3, and drying. Alternatively, a transparent electrode film obtained by depositing ITO on a polyester film can be used as the transparent electrode 4.

Further, the common back electrode 1 and the two transparent electrodes 4
The electrode lead wires 5 and 6 are derived from the. Further, the element body is packaged with a film (not shown) having high moisture resistance to form an EL element.

A process of forming the electrode lead wires 5 and 6 will be described with reference to FIG. FIG. 2 is a plan view of the common back electrode 1 of the dual emission EL device of FIG.

When the aluminum foil to be the common back electrode is anodized to form the insulating layer 2 of the aluminum oxide film, masking for covering the shaded portion 7 of FIG. 2 on one surface of the aluminum foil as shown in FIG. 8 is performed and anodization is performed. When the mask 8 is removed after the anodizing treatment, the shaded portion 7 is not oxidized and the surface of the aluminum foil remains. The common extraction electrode 5 of the back electrode is adhered to this portion 7.

After the light emitting layer 3 and the transparent electrode 4 are formed on both sides, the extraction electrode 6 is adhered to the bus bar 9 provided on both transparent electrodes 4.

In the double-sided light emitting EL device manufactured according to the above-described embodiment of the present invention, for example, the common back electrode 1 has a thickness of 8
The aluminum oxide (Al ₂ O ₃ ) insulating layer 2 formed on the surface of the aluminum foil of 0 μm has a thickness of about 1 μm at the most even if both surfaces are combined, and the light emitting layer 3 has a thickness of 50 μm.
The thickness of × 2 and the transparent electrode 4 was 10 μm × 2, and the total thickness was 201 μm.

On the other hand, the double-sided emission E by the reference technique
The thickness of the L element is the same standard, and the back electrode 10 is 8
0 μm × 2, insulating layer 20 40 μm × 2, light emitting layer 3 50 μm × 2, transparent electrode 4 10 μm × 2, total 360
It was μm. Therefore, in the embodiment of the present invention, it is possible to significantly reduce the thickness.

In the embodiment of the present invention described above,
The material of the common back electrode is aluminum foil, but the material is not limited to this, and other conductor materials can be used. Further, in order to obtain the same effect as that of the embodiment, the anodic oxidation method and the treatment of the aluminum foil are not limited to being carried out under other conditions different from those of the above embodiment.

The present invention has been described above with reference to the embodiments.
The present invention is not limited to these. For example,
It will be apparent to those skilled in the art that various changes, improvements, combinations and the like can be made.

[0046]

As described above, in the present invention, since the opposite surfaces of the conductors are used as the common back electrode, it is not necessary to double the back electrodes, and the entire double-sided EL light emitting device can be obtained. It can be made thin and the manufacturing process becomes simple.

Furthermore, if the insulating layer is formed by anodizing the back electrode, the manufacturing process is simple, the thickness of the insulating layer is thin, and the element as a whole can be formed thinner.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a dual emission EL device according to an embodiment of the present invention.

FIG. 2 is a schematic plan view of a dual emission EL device according to an embodiment of the present invention.

FIG. 3 is a diagram for explaining a manufacturing process of a common back electrode of a dual emission EL device according to an embodiment of the present invention.

FIG. 4 is a schematic cross-sectional view of a dual emission EL device according to a conventional technique.

[Explanation of symbols]

 1 Common Back Electrode 2 Barrier Type Aluminum Oxide Insulation Layer 3 EL Light Emitting Layer 4 Transparent Electrode 5 Back Electrode Lead Electrode 6 Transparent Electrode Lead Electrode 7 Aluminum Foil Exposed Area 8 Masking 9 Bus Bar

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Takahiro Saida 2-17-8 Edaminami, Midori-ku, Yokohama-shi, Kanagawa 203 Shimura Mansion 2 (72) Inventor Shuichi Taya 2-17, Edaminami, Midori-ku, Yokohama-shi, Kanagawa 8 Shimura Mansion 405 (72) Inventor Toyoshi Iida 44-15 Midorigaoka, Tsukuba City, Ibaraki Prefecture (72) Inventor Tsuyoshi Tonomura 5-9-6 Tokodai, Tsukuba City, Ibaraki Prefecture Yuko Fujii East, Tsukuba City, Ibaraki Prefecture Kodai 5-9-6 (72) Inventor Sadayoshi Yamakawa 5526-4 Teraizumi, Nagai City, Yamagata Prefecture (72) Inventor Shunichi Osawa 2-1-12 Tokamachi, Nagai City, Yamagata Prefecture

Claims (5)

[Claims] 1. A common back electrode layer made of a conductor, insulating layers formed on both surfaces of the common back electrode layer facing each other, an EL light emitting layer formed on each of the both insulating layers, and both. A double-sided light emitting EL device including a transparent electrode formed on each of the EL light emitting layers. 2. The double-sided emission EL device according to claim 1, wherein the back electrode layer includes an aluminum foil, and the insulating layer includes a barrier type aluminum oxide film formed by anodizing both surfaces of the aluminum foil. 3. A double-sided light emitting EL device comprising: a step of forming an insulating layer on each of the opposite surfaces of a conductor; and a step of forming an EL light emitting layer and a transparent electrode on each surface of the two insulating layers. Production method. 4. The method for manufacturing a double-sided light emitting EL device according to claim 3, wherein the step of forming the insulating layer includes the step of forming a barrier type aluminum oxide film by anodizing both opposing surfaces of the aluminum foil. . 5. A step of forming a region where an aluminum oxide film is not formed on a part of the surface of the aluminum foil by masking in the step of forming the insulating layer,
The method for manufacturing a dual emission EL device according to claim 4, further comprising the step of forming a lead electrode of the back electrode in a region where the aluminum oxide film is not formed.