JPS61230295A - Flexible type light emitting 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] [Field of Application of the Invention] The present invention relates to a flexible light emitting device, and is applicable to office automation equipment,
The present invention relates to a flexible light emitting element suitable for automobile equipment, household electronic equipment, and electrical equipment.

[Background of the invention]

Currently, flexible and decentralized development is being conducted at both domestic and overseas companies.

Optical devices are being developed and are being put into practical use as various liquid crystal display devices on the market, backlights for liquid crystal televisions, and various display devices.However, demand has not yet grown in earnest. This is partly due to the problem of lifespan, but also because the brightness is currently insufficient.The conventional flexible type light emitting element is Nikkei Electronics 19B0.
As described in No. 24, pp. 220-227, this structure has a fluorescent light-emitting layer and a reflective insulating layer between a transparent electrode and a back electrode. In devices that have actually been produced, the thickness of the light emitting layer (electrode spacing) is as large as 60 μm or more. Therefore, for example, when a voltage of 100 V is applied, the average electric field strength applied to the light emitting layer is 1.7 V/μm or less. The electric field dependence of the luminescence brightness of ZrLS-based phosphors, which are inherently electroluminescent, is large and is proportional to the second to fifth power of the electric field strength. Therefore, in order to increase the brightness without increasing the frequency of the applied electric field, it is necessary to add to the light-emitting layer. Average field strength of at least 2v/μm
As described above, it is necessary to improve the voltage to about 2.5 V/μm. To do this, the thickness of the light emitting layer (including the reflective layer) must be reduced from the current 60 to 70 .mu.m to about 215 .mu.m compared to the conventional one. To achieve this, it is necessary to greatly improve the dielectric strength between the two electrodes.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a flexible light emitting device which eliminates the disadvantages of the conventional flexible light emitting device described above and greatly improves brightness and luminous efficiency.

[Summary of the invention]

The present invention is a flexible type that improves the dielectric strength, reduces the electrode spacing, increases the average electric field strength applied to the light emitting layer, improves brightness, and improves the luminous efficiency by reducing the effective current during light emission. It is a light emitting element. A means for improving the dielectric strength is to provide a thin layer of titanium oxide with a thickness of 0.5 to 0.5 .mu.m on the surface of the metal foil used as the back electrode, for example, by an organometallic complex method or a sputter link method.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG. Thickness 0.1aam, which becomes the back electrode of the flexible light emitting element
A titanium alkoxide treatment solution consisting of 1 part by weight of titanium tetraisopropoxide, 1 part by weight of stabilizer acrylic ester 8A (trade name manufactured by Mitsubishi Rayon) and 155 parts by weight of a diluting solvent was applied onto an aluminum foil plate 1 by dipping or spin coating. After coating and drying, it is approximately 4 (3rn) at 450°C.
About o, 4μ on the above aluminum foil by baking in.
A structured titanium thin film 2 having a thickness of m is formed.

Next, a phosphor slurry consisting of an electroluminescent phosphor, a cyanoethylated saccharose, a cyanoethylated cellulose, and a solvent is applied onto the titanium oxide thin film 2 by a doctor blade method, and then heated and dried at 120'C. A light emitting layer S having a thickness of about 40 μm is formed. Next, the light-emitting layer 5 was subjected to a reduced pressure heat treatment for 120 tons and about 5 hours, and then heated and dried at 150 degrees Celsius in a dry atmosphere.
After laminating them and subjecting them to electrode extraction treatment, a S-fluorochloroethylene envelope 5 was placed in a heated drying atmosphere.
The peripheral portion 6 was crimped to produce a 7-lexiple type light emitting device.

As a result of examining the dielectric strength of the light emitting device according to the present invention manufactured in this manner, it was found that it had a dielectric strength of 500 μm or more, used untreated aluminum foil electrodes like the conventional device, and emitted light with an electrode spacing of 60 μm. It was better than Motoko. Low 250 Hz and 15 Hz for the device according to the invention and the conventional device, respectively.
As a result of applying a voltage of 0■ and comparing the brightness characteristics, the brightness of the conventional element was 70cd/r? , luminous efficiency 1.5 trt/W
On the other hand, the device made according to the present invention has a luminance of 1
50 cd/yd, luminous efficiency of about 2.5 ml/W,
It has been found that the luminance efficiency is greatly improved with the same dielectric strength voltage.Furthermore, another embodiment of the present invention will be described with reference to FIG.

The same reference numerals as in FIG. 1 indicate the same members. A feature of the light emitting device shown in FIG. 2 is a high dielectric constant light reflection layer shown at 6. In this example, the high dielectric constant light reflection layer is made of barium titanate or a material containing barium titanate as a main component. As a result, the dielectric strength of the light emitting device using the metal foil back electrode formed with the titanium oxide thin film according to the present invention was improved by about 1.5 times compared to the conventional device. Therefore, the electrode spacing could be reduced accordingly. Since it can be made smaller, the brightness and luminous efficiency can be approximately doubled.

In addition, as a means of forming a titanium oxide thin film on the metal foil used for the back electrode, a sputtering method using a titanium oxide target was also experimented.

In this case as well, a titanium oxide thin film with a KO of 15 to 0.4 μm is formed as described above, and the dielectric strength of the light emitting device created using this film for the back electrode is approximately 1.5 times higher than that of the conventional device. The results showed that the brightness and luminous efficiency were also approximately doubled.

〔Effect of the invention〕

As described in the embodiments of the present invention, according to the present invention, the dielectric strength of the flexible light emitting device is significantly improved.
The thickness of the light-emitting layer can be made thinner and the distance between the electrodes can be narrowed, and even when the same external electric field is applied, the average electric field strength applied to the phosphor layer increases, increasing the luminance by about twice. Can be done. Furthermore, since the insulation between both electrode layers is good, the effective current consumption and effective power consumption during the light emitting operation are reduced, and the light emitting efficiency of the device can be approximately doubled.

[Brief explanation of the drawing]

FIG. 1 is a partially enlarged vertical cross-sectional view of a light emitting device according to the present invention;
FIG. 2 is a partially enlarged vertical sectional view of another light emitting element according to the present invention. 1...Back electrode layer 2...Titanium oxide thin film layer 5...Light emitting layer 4...Transparent electrode layer 5...Envelope 6...Periphery of the generating element Patent attorney Udo Ogawa゛- A1 Akira Tomoe 2nd

Claims (2)

[Claims] 1. In a flexible light emitting element comprising a transparent conductive film, a metal foil back electrode, and a light emitting layer containing an electroluminescent phosphor interposed between the transparent conductive film and the metal foil back electrode, the back A flexible light-emitting element characterized in that a titanium oxide thin film is provided between an electrode and the light-emitting layer. 2. In a flexible light emitting element comprising a transparent conductive film, a metal foil back electrode, and a light emitting layer containing an electroluminescent phosphor interposed between the transparent conductive film and the metal foil back electrode, the back A flexible light emitting device characterized by having a titanium oxide thin film and a high dielectric constant reflective layer in contact with an electrode.