JPS59184329A - Fully solid state complementary type electrochromic display element - Google Patents

Abstract

PURPOSE:To improve responding speed, coloring density and reliability by providing an UV shielding layer consisting of a thin cerium dioxide film on a thin tungsten trioxide film. CONSTITUTION:A thin cerium dioxide film which is colorless and transparent and shuts off <=400nm wavelength is used as an UV shielding layer, thereby forming a fully solid state complementary type EC display element which prevents photochromism of the tungsten trioxide and has remarkable resistance to light. A fully solid state complementary type EC display element consisting of a transparent electrode 2, a thin iridium oxide film 3, a dielectric layer 4, a thin tungsten trioxide film 5, and a transparent electrode 6 is formed on a lower substrate 1 and further a thin cerium dioxide film 7 is formed thereon by a PVD method including ion plating. The element is thereafter sealed with an upper sealing plate 8 and a sealant 9. The preferred thickness of the thin cerium dioxide film is 0.8-1.6mum. If the thickness is <=0.7mum, the effect of preventing photochromism is slight and if >=1.7mum, the effect of the transmittivity in the visible part is not negligible.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a display element that applies an electrochemical coloring/discoloring phenomenon, that is, an electrochromic (hereinafter abbreviated as EC) phenomenon, and more specifically relates to a reduction coloring type EC material layer and an oxidation coloring type EC The present invention relates to an all-solid-state complementary type EC display element using a material layer. A complementary EC display element is a layer of a reduction color-forming EC material represented by tungsten trioxide and an iridium acid f
An EC display element having a structure in which an oxidized color-forming EC material layer and a layer of an oxidized color-forming EC material exhibit coloring and fading phenomena at the same time, and in which both color-forming EC layers are observed by overlapping each other, and each color-forming EC layer Improvement in response speed compared to an EC display element using only
It is possible to increase color density and improve reliability.

Generally, tungsten trioxide, which is used as a reduction coloring type E
It is also expected to be the closest to practical use in C display elements.

However, tungsten trioxide tends to develop a blue color called photochromism due to the ultraviolet rays contained in sunlight, etc., and when the display area is exposed to rays containing ultraviolet rays such as sunlight, even the areas to which no colored electrical signals are applied will develop color. It has the disadvantage of being

One color developed by this photochromism can be electrochemically decolored in the same way as EC coloring, so coloring and decoloring can be repeated in a short period of time, and there is almost no problem with the appearance of the display part. For areas with a long non-color development time, such as the A f'vl and PM display areas in watches, the conventional all-solid-state complementary E C display element 47'l is completely
TS, 11r, and defense, which was a major obstacle to practical application.

Ultraviolet irradiation experiment on the inventors' conventional all-solid-state complementary type C element (], 00μW/C1d)
Now, for an element that does not develop a color, blue color can be seen in about 30 minutes due to photochromism of Kutsugesten trioxide, and for an element that repeats color development and disappearance at a 2-second cycle, the power consumption is Characteristic deterioration such as an increase in response speed and a decrease in response speed was observed.

The present invention uses a cerium dioxide thin film that is colorless and transparent and blocks ultraviolet rays with a wavelength of 400 nm or less as an ultraviolet blocking layer. This is a complementary EC display element.

Examples will be explained below.

FIG. 1 is a diagram showing the cross-sectional structure of the EC display element of the present invention. An all-solid-state complementary EC display element consisting of a transparent electrode 2, an iridium oxide thin film 6, a dielectric layer 4, a tungsten trioxide thin film 5, and a transparent electrode 6 is formed on a lower substrate 1,
Furthermore, a cerium dioxide thin film 7 is formed by I) VI I) method including ion blating.

After that, sealing is performed with an upper restraining plate 8 and a sealing material 9. The thickness of the cerium dioxide thin film (Soil, 08 to 16 μm is appropriate. If the thickness is less than 0.07 μm, the effect of preventing photochromism is minimal, while if it is more than 17 μm, the effect on the transmittance in the visible region cannot be ignored. .

FIG. 2 shows a spectral transmittance curve 10 when a cerium dioxide film with a thickness of 171 m is formed on soda glass with a thickness of 0.7 mm.

Compared to the spectral transmittance curve 11 of the 0.7 mm thick Nung glass shown in the same figure, it absorbs ultraviolet light significantly (a), thereby achieving the effect of preventing photochromism of tungsten trioxide caused by light with a wavelength of 350 nm or less. .

All-solid-state complementary type 1 with the above configuration] C table; J': The device was irradiated with ultraviolet light for 300 hours (] OO/, t w /
6Fll) No blue coloring occurs at all even with K.
1) There was no change in the chemical properties.(2) There was no change in the thorium dioxide thin film. The low voltage was negligible, and no inferiority was found in this example (C) compared to the conventional all-solid-state complementary EC display element.

The upper part of the display element (light receiving (light receiving)
In both cases, a photochromism prevention effect similar to that of this example was observed in the structure in which a cerium dioxide thin film was formed on the cerium dioxide layer.

As described above, the all-solid-state complementary type EC display element according to the present invention has significantly improved light resistance, which was a drawback of the conventional one, and can be fully applied to devices that are frequently used outdoors, including wristwatches. It is a display element.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of a C display element showing an embodiment of the present invention, and Fig. 2 is a graph showing the spectral transmittance of a cerium dioxide thin film. Figure 1 Figure 2 Separate issue (nmJ

Claims (1)

[Claims] An all-solid-state complementary electrochromic display element using a tungsten trioxide film as a reduction color-forming electrochromic material, characterized in that an ultraviolet blocking layer made of a thin cerium dioxide film is provided on the tungsten trioxide film. Solid-state complementary electrochromic display element.