JPS608034B2 - Photosensitive display element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high-contrast semiconductor display element intended for low power consumption and long life.

BACKGROUND ART Conventionally, liquid crystal display elements, electrostatic display elements, electrochromic display elements, and the like are known as light-receptive display elements.

On the other hand, light emitting diode display elements (LEDs) and electroluminescent display elements are known as luminescent display elements. Each of these display elements has advantages and disadvantages, and various display devices have been developed that take advantage of these characteristics. That is, although light-receiving display elements can generally display images with low power consumption, the display substance induces an electrochemical reaction on the electrode surface, and as a result, the display substance deteriorates and the display function disappears. As a method for preventing this functional decline, processing of the electrode surface, addition of electrochemical reaction control to the display substance, etc. have been carried out. However, even with these efforts, the life of the display device is affected by the chemical stability of the substance to be displayed. Furthermore, the display operating temperature range of these light-receptive display devices is generally around room temperature, and cannot be used at low temperatures (especially below -20q0) or high temperatures (especially 70℃).
The disadvantage is that it is difficult to use in the above cases.
That is, the display function is exhibited within the temperature range of the liquid crystal phase in the phase state of the liquid crystal substance, and in electrochromics, dew pneumatic migration, etc., only within the liquid state temperature range of the dispersion solvent. Therefore, it is not suitable for display in places where the temperature is extremely low or high, such as outdoors in winter or in sunlight in summer. On the other hand, luminescent display elements display information by converting it into electrical energy, so they provide a clear display even in sunny places.Since these display elements are generally in a solid state, they have a wide operating temperature range and a long lifespan. It has many advantages,
It is a practical display element.

However, these luminescent display elements have extremely low energy conversion efficiency of 0.01 to 2%, and therefore have a decisive drawback of consuming 10 to 100" of acoustic power compared to the light-receptive display elements. From the above points of view, light-receptive display elements are used in circuit displays powered by primary or secondary batteries such as dry batteries and storage batteries, such as terminals for electronic desktop calculators, watches, and small measurement displays. Display elements are used as terminals for electronic computers and displays for various home appliances that are powered by power from a commercial AC power source.

Therefore, all of these display devices have major drawbacks and cannot be used as general-purpose display devices.

The present invention has been made in view of the above points, and provides a light-receiving display device with a long life and high contrast in which chemical reactions of display substances are unlikely to occur.

That is, the present invention provides a light-receiving display element in which a display layer containing a mixture of an electron-accepting compound and an electron-donating compound is provided between mutually insulated electrodes. Next, the device of the present invention will be specifically explained with reference to the drawings.

That is, both an electron-donating compound and an electron-accepting compound are exposed to form a charge-transfer type rust body, and the amount of transmitted light or reflected light is changed using the charge-transfer type absorption band developed at this time. This is for twill display.

That is, a composition 3 obtained by mixing an electron-donating compound and an electron-accepting compound, which are materials for forming a charge transfer type anchor with a display device structure as shown in FIG. 1, is placed on each opposing glass plate 1, for example. A voltage is applied to both ends of the NESA film 2 to form a charge transfer type rust compound, and an image is displayed based on the color of the key body at this time.

The spectral characteristics of the display element at this time are shown in FIG. Therefore, the color displayed in the image can be arbitrarily obtained by selecting an electron-accepting compound and an electron-donating compound. Furthermore, in order to reduce the display power, a display device structure as shown in FIG. It is also possible to provide an insulating layer 4 between the electrode 2 to form an MIS structure (metal-insulating layer-semiconductor layer) for image display.

That is, a negative bias voltage is applied between the metal layer 2 and the semiconductor layer 5 to form a charge transfer type compound in the semiconductor layer 5, and an image is displayed by the color of the armor body at this time. It is something. Furthermore, in the above-mentioned MIS structure with a display device structure as shown in FIG. Similarly to the above, a negative bias is applied between the metal layer 2 and the semiconductor layer 7, and a charge transfer type collar is formed at the interface between the semiconductor layer 7 and the insulating layer 6. It is used to generate a body compound and display an image. Furthermore, in the display element structure as shown in FIG. 4, an inorganic semiconductor thin film 7 is formed on the transparent electrode 2, and an insulating layer 6 containing an electron-donating compound or an electron-accepting compound is provided above the inorganic semiconductor thin film 7.
image display may be performed by applying a negative bias between the metal layer 2 and the semiconductor layer 7, and forming a charge transfer type lead body between the inorganic semiconductor layer 7 and the insulating layer 6.

On the contrary, it is also possible to use a material containing an electron-donating compound or an electron-accepting compound for the inorganic semiconductor layer 7, and form a charge-transfer type rust body with this and an insulating material to display the image. . The materials forming these display layers are listed below, but by polymerizing at least one of an electron-accepting compound or an electron-donating compound,
Not only a conventional flat display device but also a three-dimensional display device can be formed.

In addition, by increasing the molecular weight of the display material and patterning the display layer using an appropriate method (e.g., printing method, photoetching method, etc.), it is possible to create a display layer that has a high molecular weight. It has the feature that it can be manufactured easily and with a smaller amount of display material without requiring the display material to be present in the display area.

The display element of the present invention comprises tetracyanoxydimethane (TCN).
Q), an electron-accepting compound consisting of at least one kind of tetracyanoethane (TCNE), and an electron-donating compound consisting of a polyamine having a repeating unit represented by the following formula, as a display layer. It is used as a material.

Further, these electron-accepting compounds and electron-donating compounds may be used by dissolving them in an appropriate organic solvent such as acetonitrile, dimethylformamide, acetone, etc., or they may be used by dissolving them in an appropriate organic solvent such as acetonitrile, dimethylformamide, acetone, etc. It may also be dispersed or dissolved in a semi-solid. Transparent electrodes used in the present invention include, for example, SOS (silicon on sapphire) glass substrates on which a transparent conductor such as tin oxide or indium oxide is formed, as well as metals.

Any material may be used as long as it is a low resistance material such as aluminum and does not absorb visible light. On the other hand, the insulating layer and the semiconductor layer in the MS structure of the display cell may be controlled by the coarse ratio of the electron-accepting compound and the electron-donating compound and their concentration to form a junction.

Further, as these supports, it is also possible to use a thick polymer which forms a charge-transfer type rust body as described above, as well as aerosil, zinc oxide powder, calcium carbonate powder, zirconium, and the like. The display layer in the present invention is selected in the range of 0.5 to 50 degrees, although it varies depending on the contrast of the image to be obtained.

In addition, the insulating layer and semiconductor layer in the display cell only need to have resistance to negative bias, and generally 0.5
~10 is sufficient. The characteristics of the display element according to the present invention having such a structure are such that a contrast ratio of 0.1 to 20 can be obtained, and the power consumption is 10 French W', which is compared to a liquid crystal display element which is said to be a low consumption display element. It is also possible to obtain about 1/10 of the amount. Furthermore, by forming this semiconductor display element on an integrated circuit substrate and also providing and integrating a driving circuit, such as a matrix circuit, and a CCD (charge transfer type device) on the same substrate, the method similar to that of ordinary integrated circuit technology can be used. It can be manufactured by

The details of the present invention will be explained by giving examples.

Example 1 Synthesis of electron-donating compound A polyamine was synthesized as an electron-donating compound by the following method.

0.5 mol N-methylaniline and 200 Z
N and N' dimethylformamide are provided respectively. Separately, 0.5 mol piverazine dihydrochloric acid monohydrate was dissolved in 200 m of water, and then poured into water. To this, 1 mol of 37% formalin aqueous solution was gradually added, and a homogeneous solution was transferred to the dropping funnel. The contents of the four-necked flask were cooled with water while vigorously concentrating, and an aqueous formalin solution of the amine was gradually added dropwise from the dropping funnel over 1 hour.

After that, after reacting at room temperature for 5 hours, the reaction solution was
The precipitate was poured into a 10% NaOH aqueous solution, and the reprecipitate was washed with water and then dried under vacuum. The dried sample is dissolved in benzene and reprecipitated with petroleum ether. The melting point of this thing is 17
It was 0q0. From the IR spectrum and NM Nagisu vector of this polyamine compound, it was estimated to be represented by the following chemical formula. (n indicates the number of repetitions of polymerization.

)25q0 The intrinsic viscosity in benzene was 0.30.

Formation of TCNE charge transfer body A polymer represented by the formula '1' was dissolved in ethane dichloride to give a concentration of 5 mol', and TCNE was mixed in this so that 0.5 mmol' was obtained. When the mixture was left at room temperature for one day and night, a pale reddish-purple polymer solution was obtained.

From the absorption spectra, it was confirmed that these compounds formed a charge-transfer type compound.

Next, the polymer represented by the formula (1) was dissolved in ethane dichloride to give a concentration of 5 mol/ml, and TCNEO.
Mix at a concentration of 1 mmol/sol and leave for one day to remove ethane dichloride.

Next, TCNE was added to polyethylene glycol (Soekawa Chemical #
1500), and mixed with the above polymer powder while heating, and coated on a transparent electrode plate in 50 mounds.

A display cell with the structure shown in Figure 1 was created by placing transparent electrodes on this coating film, and when 20 V AC was applied between both electrodes, a deep reddish-purple color developed, and this image had a contrast ratio of 1:20. It had FIG. 5 shows the absorption spectra before and after voltage application. Next, the coating film obtained above is 107
A display cell with a structure as shown in Figure 1 was created by placing a 1000A thick Si02 thin film on a transparent electrode on top of this semiconductor layer, and connecting both electrodes. When a direct current of 20 V was applied between them, a deep reddish-purple color developed, and this image had a contrast of 1:10.

Example 2 The polymer obtained in Example 1 was dissolved in ethane dichloride to a size of 5 mm.
Mix it so that it becomes a solid mixture, and add TCNQ to this mixture.
Mix at 0.1 mmol/〆 and place on SOS (
The substrate (silicon (1000A) formed on sapphire) was left for one day and night to remove ethane dichloride.

This thin film layer was a semiconductor having a resistivity of 1. Separately, on this thin film, a display portion was formed using a screen printing method using a wax in which TCNQ was dispersed in polyethylene glycol (#1500 manufactured by Soekawa Chemical Co., Ltd.) to a thickness of 50 μm.

A transparent electrode was placed above this to create a front cell with a structure as shown in FIG. When a direct current of 15 V was applied between both transparent electrodes, a deep reddish-purple color developed, and the contrast of this image was 1:15. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram for explaining an embodiment of the device of the present invention, FIG. 2 is a spectral characteristic curve diagram of FIG. 1, and FIGS. 3 and 4 are other embodiments of FIG. 1. FIG. 5 is a spectral characteristic curve diagram of another specific example of the device of the present invention.

1 is a glass layer holding a transparent electrode, 2 is a transparent electrode, 3 is a display layer consisting of a mixture of an electron donating compound and an electron accepting compound, 4 is an insulating layer, and 5 is an electron donating compound and an electron accepting compound. 6 is an insulating layer containing an electron-donating compound or an electron-accepting compound; 7 is a semiconductor layer made of a material that forms a charge transfer type chain compound with the compound contained in 6; 8 is the thickness between the electrodes; A smoother to keep it clean.

Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Scope of Claims] 1. A polyamine having substantially the following repeating units provided between electrodes, at least one of which is transparent; 1. A light-receiving display element comprising a display layer containing a mixture of at least one type of light-receiving display element. 2. The light-receiving display element according to claim 1, wherein the mixture is a semiconductor. 3. The light-receiving display element according to claim 1, wherein the display layer includes a laminated structure of a semiconductor layer and an insulating layer. 4. The light-receiving display element according to claim 1, wherein the element layer has a laminated structure of an inorganic semiconductor thin film and an insulating layer containing an electron-donating compound or an electron-accepting compound. 5. The light-receiving display element according to claim 1, wherein the display layer has a laminated structure of a semiconductor thin film containing an electron-donating compound or an electron-accepting compound and an insulating layer.