JPS6118165B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a solid state electro-optical device whose electromagnetic radiation transmission properties can be reversibly changed by a suitably controlled electric field. An object of the present invention is to provide a fully solid-state display device with high contrast.
This display device is characterized in that the electrochromic solid layer is subjected to electrochemical chemical conversion treatment, and can easily undergo color decolorization or reversible color change under the action of an electric field.

According to the definition of the present invention, an electro-optical device means a device that changes color when a suitable electric field is applied to it. In such a device, a color change is induced by applying an electric field with a certain polarity.
It contains an electrochromic material that undergoes color reversal by applying an electric field of opposite polarity. Several types of solid-state electrocoloring devices have been announced so far. The simplest of these consists of a pair of electrodes, at least one of which is transparent, with an electrochromic material such as tungsten oxide sandwiched between them. However, the electrochromic layer of such a simple sandwich structure is produced by vacuum deposition or the like, and is not subjected to electrochemical conversion treatment as in the present invention. Therefore, it has been difficult to perform and control color reversal by the action of an electric field. Control and speed of color reversal operation was improved by inserting a second layer between the electrodes. This second layer is characterized as a current carrier permeable insulator in U.S. Pat. No. 3,521,941 to Deb et al. The insulator used by Deb et al. is selectively incorporated into the electrochromic material to be suitable for producing a lasting color. Although such devices from outside the debris modulate the transmitted light, similar devices using reflective electrodes can be used as reflective displays that modulate the reflected light. The above-mentioned prior art uses an electrochromic material that is already formed by a method such as a vacuum evaporation method or a sputtering method. but,
Such an electrochromic material is difficult to change color due to the action of an electric field, and even if it does change color, it is too small to be of practical use.

The present invention eliminates these drawbacks by subjecting an electrochromic material produced by conventionally known methods such as vacuum evaporation, sputtering, and ion plating to an electrochemical conversion treatment. , which is directly or indirectly inserted between two electrodes, at least one of which is transparent, to provide a solid-state display device with high contrast.

Next, the electrochromic solid material referred to in the present invention is generally an electrical insulator or semiconductor. Therefore, metals, metal alloys and other metal-containing compounds that are relatively good conductors of electricity are excluded. Useful materials that generally exhibit electrochromic properties over a wide temperature range, ie, from -50 DEG C. to 125 DEG C., include, for example, tungsten oxide, molybdenum oxide, panadium oxide, niobium oxide, tantalum oxide, and uranium oxide.

Next, electrochemical chemical conversion treatment means applying an electric field to the electrochromic layer mentioned above in an electrolytic solution to perform electrochemical conversion treatment, and it is especially better to perform reduction treatment on the cathode side. Yes, but don't limit yourself to this.

At least one of the electrodes may be a transparent electrode made of indium oxide, tin oxide, gold, titanium oxide, or the like.

In addition, an electrochromic solid layer subjected to electrochemical conversion treatment may be inserted directly between two electrodes, and oxides, nitrides, sulfides, organic materials, fluorides, chlorides, bromides, iodides, selenium A chemical compound, arsenide, etc. may be inserted as a second layer. The thickness of this second layer is preferably 0.001 to 1.0 μm, but is not limited to this.

Next, specific examples of the present invention will be shown.

FIG. 1 shows the simplest example of the present invention, in which 1 is an electrochromic solid layer subjected to electrochemical conversion treatment;
is a transparent substrate such as glass or plastic; 3 is a transparent electrode such as indium oxide or oxide; and 4 may be a transparent electrode or an opaque electrode such as metal. Now, tungsten trioxide as an electrochromic material is vacuum deposited on a transparent electrode formed on the surface of a glass substrate to form a thin film. Next, when an electrochemical conversion treatment is performed in a dilute sulfuric acid aqueous solution so that the tungsten oxide side becomes negative with respect to the counter electrode, the tungsten oxide layer develops a deep blue color. After this is pulled up, washed with water, and dried, a transparent electrode of indium oxide is vacuum-deposited on the tungsten oxide film. In this way, the apparatus of the present invention as shown in FIG. 1 is completed. When an electric field is applied between these two electrodes, color develops, and when the electric field is removed, the color disappears. If no electrochemical conversion treatment is performed, no color develops, but if the electrochemical conversion treatment of the present invention is performed, a blue color develops.

Next, as shown in FIG. 2, a second layer is laminated on the electrochromic solid layer 1 that has been subjected to electrochemical conversion treatment. 1 to 4 are the same as in FIG. 1, and 5 is an insulating layer or a semiconductor layer.

As in FIG. 1, a transparent electrode of indium oxide is formed on the surface of a glass substrate, and a molybdenum oxide layer is further formed thereon by sputtering. As mentioned above, this was electrochemically treated in a dilute sulfuric acid aqueous solution to develop a color, and then washed with water.
After drying, a magnesium fluoride layer is formed thereon by vacuum evaporation. Furthermore, a transparent electrode made of indium oxide is attached on top of that. In this way, the apparatus of the invention shown in FIG. 2 is produced. Electrode 3 between electrodes 3 and 4
When a DC voltage is applied so that the electrode becomes the cathode, a deep blue color develops, and when a voltage of the opposite polarity is applied, the color disappears. In this case, the absorbance of color development is approximately 10 times greater than that in the case where the electrochemical conversion treatment, which is a feature of the present invention, is not performed. Therefore, the contrast is approximately 10 times greater than before. When anodic treatment is performed using electrochemical chemical conversion treatment, color development is small, but color development still occurs due to the action of an electric field.

As described in detail above, according to the present invention, it is possible to obtain a solid-state electro-optical device with high contrast, and its industrial applicability as a display device is great.

[Brief explanation of the drawing]

1 and 2 are cross-sectional views of embodiments of the solid-state electro-optical device according to the present invention. 1... Electrochromic solid layer subjected to electrochemical conversion treatment, 2... Transparent substrate, 3... Transparent electrode, 4
... Electrode, 5 ... Insulator layer or semiconductor layer.

Claims (1)

[Scope of Claims] 1. A solid electro-optical device characterized in that an electrochromic solid layer subjected to electrochemical conversion treatment is sandwiched between a pair of electrodes, at least one of which is transparent. 2. The solid-state electro-optical device according to claim 1, characterized in that an insulating layer or a semiconductor layer is interposed between at least one electrode and the electrochromic solid layer.