JPH06275864A - Light-to-light conversion element - Google Patents

Abstract

PURPOSE:To enhance the light-to-light conversion efficiency of the title conversion element by a method wherein at least one photoconductive layer which converts light into electricity is formed between two electrodes, a light-emitting organic thin film which converts electricity into light is sandwiched and held and the photoconductive thin film is composed of an organic thin film. CONSTITUTION:An electrode layer 11 into which holes are injected, an organic thin-film layer (a first layer) 1 which transports holes, an organic thin-film layer (a second layer) 2 in which holes are recombined with electrons so as to generate light, a photoconductive thin film (a third layer) 3 which generates holes and electrons from light and which is composed of an organic thin film and an electrode layer 12 into which electrons are injected are laminated sequentially on a support substrate 10 such as a glass or the like. The organic thin film whose function to generate electrons and holes is high by absorbing light is used for the third layer, and its material is preferably a material whose conversion efficiency from light into electricity is high and whose electron injection barrier is less than 0.7eV when the second layer is viewed from the third layer. Thereby, the light-to-light conversion efficiency of the title conversion element can be enhanced to about 50 times that in conventional cases.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light-to-light conversion element used as a central element of an optical address type electroluminescent display device, an optical operation device, an optical wavelength conversion device, an optical spatial modulation device and the like.

[0002]

2. Description of the Related Art The inventors of the present invention have hitherto been known to use a light-emitting thin film having a light-emitting function by injecting electric charge between two electrodes and a photoconductive thin film having a light-conducting function by absorbing light. An element for converting light into light (hereinafter referred to as a light-light conversion element) has been proposed (Japanese Patent Application No. 02-174445 and Japanese Patent Application No. 02-174445).
-174446). This light-to-light conversion element is provided by controlling the electron injection from the photoconductive thin film to the light emitting thin film by light. As such a photoconductive thin film, an inorganic amorphous thin film (amorphous silicon carbide: a-
The conversion efficiency (Φp) from light to light using SiC: H)
As for p), 0.91% is obtained.

[0003]

SUMMARY OF THE INVENTION The present invention is to improve the light-to-light conversion efficiency in a light-light conversion element.

[0004]

That is, according to the present invention,
In a light-to-light conversion element, in which at least one layer of a photoconductive thin film for converting light to electricity and a luminescent organic thin film for converting electricity to light are sandwiched between two electrodes, the photoconductive thin film is , A light-to-light conversion element comprising an organic thin film, and more preferably a light-to-light conversion device in which an electron injection barrier from the photoconductive thin film to the luminescent organic thin film is 0.7 eV or less. A light conversion element. Hereinafter, each component of the present invention will be described with reference to the drawings.

FIG. 1 shows an example of the embodiment, wherein 1 is an organic thin film layer for transporting holes, 2 is a luminescent organic thin film layer for recombination of holes and electrons to emit light, 3 is a photoconductive organic thin film layer that absorbs light to generate holes and electrons,
Reference numeral 10 is a support substrate such as a glass substrate, 11 is a first electrode for injecting holes, and 12 is a second electrode for injecting electrons.

That is, an electrode layer (first electrode) 11 for injecting holes, an organic thin film layer (first layer) 1 for transporting holes, and holes and electrons are formed on a supporting substrate 10 such as glass. An organic thin film layer (second layer) 2 that recombines to generate light, a photoconductive thin film (third layer) 3 including an organic thin film that generates holes and electrons from light, and an electrode layer for injecting electrons This is a light-to-light conversion element in which (second electrode) 12 is sequentially laminated. In this device, the third layer corresponds to the photoconductive thin film that converts light into electricity, and the second layer corresponds to the light emitting thin film that converts electricity into light. The electron injection barrier from the photoconductive thin film to the light emitting organic thin film corresponds to the electron injection barrier from the third layer to the second layer. This electron injection barrier is as small as possible,
Desirably less than 0.7 eV, more preferably 0.3 eV
The following is desirable.

As the third layer, an organic thin film having a high function of absorbing light and generating electrons and holes is used. It is preferable that the material has a high conversion efficiency from light to electricity, and that the electron injection barrier when the second layer is viewed from the third layer is less than 0.7 eV. Perylene derivatives such as Me-PTC are suitable.

As the second layer, an organic thin film having a high function of generating light by recombination of holes and electrons is used. The material is not particularly limited, but a material having an electron injection barrier of less than 0.7 eV as seen from the material of the third layer, having a good thin film property and having a high fluorescence yield is preferable. t-BuPh-PT
Perylene derivatives such as C are suitable.

As the first layer, an organic thin film having a high hole transporting function is used. The material is not particularly limited, but a material that is transparent to generated light and has high hole mobility is preferable. N, N, N ', N'-
tetrakis (m-methylphenyl)-
Diamine derivatives such as 1,3-diaminobenzene are suitable.

As a method for forming the organic thin film, a vacuum deposition method, a coating method or the like is appropriately used, although not limited thereto. The thickness of the organic thin film is not particularly limited, but is usually 10 to 100 nm for the first layer and 10 to 1 for the second layer.
The range of 00 nm and the third layer of 100 to 1000 nm is preferably used.

As the first electrode, it is preferable to use a thin film which has a high hole injection efficiency in the first layer, is transparent to output light, and has a high electric conductivity. The material is not particularly limited, but a transparent conductive thin film such as indium tin oxide is preferably used. For the second electrode, it is preferable to use a thin film that has a high electron injection efficiency to the third layer and is transparent to the input light. The material is not particularly limited, but preferably, a semitransparent film of gold or a transparent conductive thin film such as indium tin oxide is used. Hereinafter, an example of an embodiment of the present invention will be described with reference to examples.

[0012]

[Examples] Further examples will be described in detail. [Example 1] An indium tin oxide film was formed on a glass substrate to form a first electrode. On top of that PDA (N, N,
N ', N'-tetrakis (m-methylph
enyl) -1,3-diaminobenzene)
50 nm of the organic thin film of was formed as a first layer. An organic thin film of t-BuPh-PTC was formed thereon with a thickness of 50 nm to form a second layer. An organic thin film of Me-PTC was formed thereon to a thickness of 500 nm to form a third layer. Further, a semitransparent thin film of Au was formed on it to form a second electrode, and a light-light conversion element as shown in FIG. 1 was obtained.

A voltage was applied to this element so that the first electrode was positive and the second electrode was negative, light was input from the second electrode side, and output light was extracted from the first electrode side. As input light, wavelength 632.8 nm, intensity 0.01 mW / c
At m ² , the output light was broad light centered at 680 nm and had an intensity of 0.00425 mW / cm ² .
This indicates that the conversion efficiency from light to light is 42.5%. The conversion efficiency is improved about 50 times as compared with the conventional light-light conversion element. At this time, the electron barrier between the second organic layer and the third organic layer is about 0.3 eV, which is smaller than the electron barrier of about 0.7 eV in the conventional device.

[0014]

In the light-to-light conversion element, the photoconductivity layer is an organic thin film, and the electron barrier from this layer to the organic light-emitting thin film is preferably less than 0.7 eV, whereby light to light conversion is achieved. The efficiency of conversion to 50 times higher than before.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a layer structure of a light-light conversion element of the present invention.

[Explanation of symbols]

 1 Organic thin film layer that transports holes 2 Organic thin film layer that recombines holes and electrons to emit light 3 Organic thin film layer that absorbs light and generates holes and electrons 10 Support substrate such as a glass substrate 12 Holes First electrode for injecting 13 Second electrode for injecting electrons

Claims (2)

[Claims] 1. A light-to-light conversion element in which at least one layer of a photoconductive thin film for converting light into electricity and a light emitting organic thin film for converting electricity into light are sandwiched between two electrodes, The light-to-light conversion element, wherein the photoconductive thin film is an organic thin film. 2. The light-to-light conversion element according to claim 1, wherein an electron injection barrier from the photoconductive thin film to the light emitting organic thin film is less than 0.7 eV.