JPS5991423A - Electrochromic display element - Google Patents

Abstract

PURPOSE:To obtain an electrochromic display element (ECD) having a display color different from the coloring specific to an electrochromic (EC) material by making best use of the light interference effect of an EC layer. CONSTITUTION:A light reflective metallic electrode Pt 10 is provided on a substrate 11, and a tungsten oxide film 13 is vapor deposited to 3,000Angstrom thickness to form a display electrode. A light transmittable back substrate 11 is used and an electrolyte 14 is injected between the substrates, thereby forming an ECD cell. The display color can be changed by using the film by which the display state like a white mirror having a slightly yellowish color in the stage of erasing provides a color display in a green color when a voltage is impressed between the electrode 10 and a counter electrode 12 and which has different film thicknesses and refractive indices. If the EC layer is tungsten oxide, the film having 2,000-4,000Angstrom thickness, and 3,900-5,000Angstrom peak position of light absorption, and 4,900-6,500Angstrom peak position of light reflection is preferred and the display in green, bluish green and yellowish green is preferred as the display color.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a display element using an electrochromic substance as a display material, and particularly to the structure of a display electrode.

Structure of the conventional example and its problems The structure of an electrochromic display element (hereinafter abbreviated as ECD) using a transition metal compound such as tungsten oxide in the electrochromic layer (hereinafter abbreviated as EC layer) is as follows.
Conventionally, a light reflective cell structure as shown in FIG. 1 or a light transmissive cell structure as shown in FIG. 2 has been used. The same reference numerals in FIGS. 1 and 2 indicate the same elements, and 1 is a transparent substrate (e.g. glass), 2 is a transparent conductive film (e.g. In 203
．． 3 is an EC layer of a transition metal compound (e.g. W○32M003), 4 is a light reflecting plate (e.g. Al
2O3 plate, TiO2 organic film), 5 is a counter electrode, 6 is a liquid electrolyte, 7 is a back substrate, 8 is a solid electrolyte, and 9 is a light-transparent counter electrode (eg, Au thin film, In203). In both cases shown in Fig. 1 and Fig. 2, the spectrum changes as shown in Fig. 3 are shown, and most of the light passes through the EC layer, and the light reflected at the interface of the EC layer is
Electrode 2 or electrolyte (6 or 8) in contact with the EC layer
It is weak because the difference in refractive index between
Almost no optical interference light from the layer is observed, and when coloring occurs, the unique coloring of the EC layer (blue if the EC layer is made of tungsten oxide)
was observed, and upon erasing, a colorless state was observed.

As mentioned above, in conventional ECDs, the display colors are limited to the colors unique to the EC layer, and it is difficult to produce other display colors using the same EC material.

Purpose of the Invention As described above, the present invention provides a display color that can be displayed using an EC substance.
Not limited to the coloring unique to the substance, the same EC material can also be colored differently from the coloring unique to the EC material by making maximum use of the light interference effect of the EC layer described in 1.1. An object of the present invention is to provide a display element having display colors.

Structure of the Invention In the present invention, a light-reflecting metal electrode is used as a display electrode, and an EC layer is provided thereon.

In the above configuration, by arbitrarily controlling the optical refractive index and film thickness of the EC layer, the absorption peak position of optical interference light changes, resulting in a display color different from the coloring unique to the EC material. This is something that can be obtained.

Description of examples Example 1 FIG. 4 shows an embodiment of the present invention.

As shown in the figure, a light reflective metal electrode (pt
A vapor deposited film with a thickness of 0.3 μ) 10 is provided,
A tungsten oxide film 13 with an optical refractive index of 1.86 is placed on the surface.
A display electrode was formed using a vapor deposition method to obtain a film thickness of 3,000 yen. The refractive index of the film 13 depends on the packing density of the film itself, and was controlled by the degree of vacuum during vapor deposition. The display electrode created as described above is placed inside using a light-transmitting back material 11, etc., and propylene carbonate is coated with Li.
f The dissolved electrolyte 14 was injected to create an ECD cell.

12 is a counter electrode (carbon electrode).

FIG. 5 shows the spectrum of the ECD created as described above during erasure and display.

As shown in the figure, when erasing, a white mirror-like display state with a slight yellowish tinge appears, but when a voltage of 1V is applied between the counter electrodes 12 with the metal electrode 10 as the negative electrode, a green color display is made, and when a reverse voltage is applied, I was able to restore it to its original state.

Example 2 As a metal electrode in Example 1, Cr was deposited on a glass substrate.
(thickness 0.5μ) and further Au (thickness 1.57z
) was used to create an ECD cell in the same manner as in Example 1. The display color in this cell was green.

Example 3 In Example 1, the display colors were investigated by varying the state of the EC layer, and the results are shown in the table below.

As shown in the table, the display color could be changed by using EC layers with different thicknesses and refractive indexes.

The above results were in good agreement with the theoretical formula for membrane interference. That is, the light absorption peak position (dark part) λ1 and the light reflection peak position (bright part) λ2 are expressed by (where m is an integer, n is the optical refractive index of the film, and d is the film thickness).

When the EC layer is made of tungsten oxide, if the film thickness is too thin, the color density will be low, and if it is too thick, the speed of color development, that is, the display response will be slow. Light absorption peak position, 3900
People ~ 5000 people, light reflection peak position 4900 ~ 660 people
0 person's membrane is good and the display color is green.

Blue-green and yellow-green displays were preferred.

Example 4 FIG. 6 shows a solid electrolyte type embodiment.

A light-reflecting metal electrode 10 (Ti, thickness 500 mm) is placed on the substrate 1.
0 people) and a tungsten oxide film (thickness 30m) on top of it.
oO person) 13 is provided, and a solid electrolyte membrane 15 (Li
F.

2000 layers thick, and finally a transparent electrode (Sno2) 16 is provided in a laminated manner.

In the cell described above, when a voltage was applied between the electrodes 16 with the metal electrode 10 as the negative electrode, a green display was obtained.

Note that the metal electrode is not limited to any type as long as it is a light-reflective material such as Al, Ni, Pd, or Cr, and it is also possible to use a metal plate. . In addition, although an example in which tungsten oxide was mainly used as the electrochromic layer was described, other Mo
O3, T i○2. Cr2O3゜V 20s + S
Any material having an EC phenomenon, such as r T 103 organic polymer film, has the effects of the present invention.

Effects of the Invention As described above, the present invention provides an ECD that makes it possible to obtain a display color different from the coloring unique to the EC material by making maximum use of the interference color of the EC material layer. Therefore, its industrial value is extremely high.

[Brief explanation of drawings]

1 and 2 are cross-sectional views of a conventional electrochromic display element, FIG. 3 is a diagram showing changes in the optical spectrum of a conventional electrochromic display element, and FIG. 4 is a cross-sectional view of a conventional electrochromic display element. FIG. 6 is a cross-sectional view of a chromic display element, and FIG.
The figure is a sectional view of an electrochromic display element according to another embodiment of the present invention. 1.11...Substrate, 10...Light reflective metal electrode, 12...Counter electrode, 13...Tungsten oxide film, 14...・Electrolyte, 15...
...Solid electrolyte membrane. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 1□Yu

Claims (1)

[Claims] (1) An electrochromic display element characterized in that a display electrode and a counter electrode are in contact with an electrolyte, and an electrochromic layer is provided on a light-reflecting metal electrode as the display electrode. (Moan) A patent characterized in that the light absorption peak (dark area) due to interference of the electrochromic layer is in the range of 39008 to 6000, and the light reflection peak (bright area) is in the range 49008 to 6500. An electrochromic display element according to claim 1.