JPS60258519A - Electrochromic element - Google Patents

Abstract

PURPOSE:To improve durability without using the 3rd electrode by forming a counter electrode of a conductive material on which a polymer film consisting of triphenyl amine is formed. CONSTITUTION:An electrochromic element is constituted with a transparent substrate 1, a conductive transparent electrode 2, an insulating film 3, a back substrate 4, the counter electrode 5, a light scattering plate 6, a sealing resin 7 contg. a spacer, a sealing resin 8, an electrolyte soln. 9 and a thin WO3 film 13. The counter electrode 5 is manufactured of the conductive material on which the polymer film consisting of triphenyl amine is formed. The durability is thereby remarkably improved without using the 3rd electrode. The EC element having the excellent durability is thus manufactured.

Description

Detailed Description of the Invention (Technical Field) The present invention relates to a display element that utilizes an electrochemical redox reaction, and more specifically relates to a conductive material formed with a triphenylamine polymer film as a reversible redox material. This invention relates to an electrochromic element with improved moisture resistance that is used as a counter electrode.

(Prior Art) Many display elements using electrochemical redox reactions have been proposed, and an example of this internal reflection electrochromic element is disclosed in Japanese Patent Application Laid-Open No. 57-158282 by the present applicant.
There are some that are listed in the publication.

The electrochromic element described in this publication (well, the fourth
It is constructed as shown in the figure, that is, a conductive transparent electrode 2 is set on a transparent substrate l, and a display electrode 18 made of a WO8 thin film having a predetermined pattern is provided thereon.
An insulating film 8 such as a SiO film is applied to a portion of the transparent electrode 2 other than the lead wire connection portion and the display pattern portion, and a counter electrode 5 is provided on one back substrate 4. are held parallel to the display electrode 18 via a spacer-containing sealing resin 7 applied around them, and a light scattering plate 6 is provided between these display electrodes 13 and the counter electrode 5. An electrolyte solution 9 is injected, and an injection port is sealed with a sealing adhesive 8. This electrochromic element uses a Prussian blue material as the counter electrode material. That is, for example, cloth-like carbon fibers (manufactured by Nippon Carbon Co., Ltd.) are used, and each 0.
Carbon fibers were immersed in a solution containing 0.01 (Vt) ferric sulfate and 7-potassium erythyanide, and electrolytically reduced at a current density of 2 J mA/c- per apparent surface area for 40 seconds to form a Prussian blue film on the surface. was formed to produce a counter electrode. FIG. 5 shows a cross-sectional view of the counter electrode prepared in this manner. In the drawing, 14 indicates a Prussian blue film, 11 indicates a lead wire for the counter electrode, and 12 indicates a conductive material for the counter electrode.

It is known that the Prussian blue described above decomposes at temperatures above 150°C. Therefore, when manufacturing an electrochromic device, especially in the process of holding the display side substrate and the rear substrate parallel to each other via the spacer 7, it is necessary to use a sealant (e.g. epoxy). Main agent LOB804 (manufactured by EHO Co., Ltd., trade name): glass fiber or alumina powder impregnated with imidazole curing agent 2PZ (manufactured by Shikoku Kasei Co., Ltd., trade name) -25:2) is used as a spacer and displayed. It is necessary to overlap the side substrate and the back substrate and bond them under pressure at 150° C. or less, for example, 130° C. for 1 hour. Inject an electrolyte solution (for example, propylene carbonate to which 1 mol/l LielO has been added) into the empty cell obtained in this way, and connect the injection port 15 of the electrolyte solution with adhesive 8 (Three Bond TB2002: TB2).
108-100:8).

(Problems to be Solved by the Invention) The electrochromic device obtained as described above was left at 60°C and 95% relative humidity for 1000 hours, and its display performance was measured. There was a problem with the drop. When we investigated the cause of this, we found that the water content in the electrolyte solution was 0.2% by weight before it was left standing.
However, after standing, it significantly increased to 10% by weight, which was found to be the cause of the dissolution of the WO8 display electrode, which caused the film thickness to become warped. Furthermore, it was found that this increase in moisture was due to moisture penetrating through the sealant 7 and entering.

Therefore, to solve this problem, it is desirable to use a sealant with low moisture permeability. For example, a combination of an epoxy resin base agent and a curing agent, such as those used in semiconductor IC encapsulants, may be used.

However, since the curing temperature of such a sealing agent is as high as 150° C. or higher, the conventional Prussian blue pair electrode material has a problem in that the Prussian blue decomposes or falls off. That is, when the Prussian blue counter electrode material prepared as described above was heated at 180° C. for 1 hour, the amount of reaction electricity before and after heating decreased to about % as shown by the broken line a in FIG. 3. This bubble cyan blue (general formula Fe, (Fe
(ON)6) 8 ・14.5H,O or KFe (Fe(ON)6-1.9H,O) The crystal water in evaporates, and the change in volume causes cracks in Prussian blue, causing it to separate from the conductive material. This is thought to be due to a decrease in the reaction amount due to shedding and Prussian blue thermal decomposition.

It is also possible to use WO2 as the counter electrode, but since initial reduction is required, the eighth electrode must be used.

This invention was made in view of these conventional problems, and by providing a counter electrode material with improved heat resistance using a triphenylamine polymer that is stable in a reduced state as a counter electrode material, the above problems can be solved. The purpose is to solve problems.

(Structure of the Invention) The electrochromic display element using electrochemical redox reaction of the present invention is characterized in that a conductive material formed with a triphenylamine polymer film is used as a counter electrode. .

The triphenylamine polymer uses 4,4',4'-)dihalogenotriphenylamine as a starting material, for example as proposed in Japanese Patent Application Nos. 59-68986 and 59-68987 by the present applicant, There are copolymers obtained by homopolymerizing this with a nickel catalyst such as dipronickel through an intermediate between this and metallic magnesium, or by copolymerizing it with 4,4'-dihalogenobenzene. It is used as a material.

The electrochromic display element (E) of the present invention was disclosed in Japanese Patent Application Laid-Open No. 57-15 except that the three elements used a conductive material on which a polymer film of triphenylamine was formed as a counter electrode.
It has the same configuration as the EC element disclosed in Japanese Patent No. 8282. The counter electrode can be produced by, for example, kneading a triphenylamine polymer with a binder to form a film, sandwiching, for example, a titanium (Ti) mesh between the two films, hot pressing, and then firing. . In this case, the counter electrode material other than the above-mentioned Ti network is
As disclosed in Japanese Patent No. 157219, various metal plates, nets, foams, carbon fibers, nonwoven fabrics, etc. can be used.

In this invention, as the sealing resin material, it is preferable to use an epoxy resin as a main ingredient, which has low moisture permeability even at a high curing temperature, in combination with a curing agent.

(Example of the invention) The present invention will be explained below based on the drawings.

FIG. 1 shows a cross section of an EC device according to an embodiment of the present invention, which is the same as that described in FIG. 3 except that a conductive material on which a triphenylamine polymer film is formed is used as the counter electrode 5. Consists of configuration. That is, in FIG. 1, 1 is a transparent substrate, 2 is a conductive transparent electrode, 8 is an insulating film, 4 is a back substrate, 5 is a counter electrode, 6 is a light scattering plate, 7 is a sealing resin containing a spacer, and 8 is a sealing member. 9 is an electrolyte solution, 1
a indicates a W08 thin film. 2a and b are cross-sectional views and plan views of the counter electrode of the EC element shown in FIG. 1, 10 is a triphenylamine polymer film, 11 is a lead wire for the counter electrode, and 12 is a conductive material for the counter electrode. shows.

Example 1 An electrochromic device having the structure shown in FIG. 1 was manufactured. However, the transparent substrate 1 and the back substrate 4 are made of glass, and the transparent electrode 2
is SnO, the insulating film 8 is a vapor deposited film of SiO, the light scattering plate 6 is a porous alumina substrate, and the electrolyte solution 9 is 1 mol/l.
Li040. was used.

For the counter electrode, 7 parts by weight of poly(4,4',4'-triphenylamine), 2 parts by weight of acetylene black, and 1 part by weight of Teflon powder were thoroughly kneaded to form a 50 μm film.
Two of these films were sandwiched between titanium (Ti) nets, and
Hot pressing was performed at °C. After that 250-80
It was fired at 0° C. for 1 hour or more and used as a counter electrode.

The counter electrode constructed in this manner has the same effect as shown in FIG. 8 even if it is heat-treated for 1 hour at 180°C under the curing conditions of an epoxy resin with low moisture permeability. As shown in b, no decrease in the amount of reaction electricity was observed.

In addition, the main resin material for sealing is Epicoat 828.
100 parts by weight, curing agent: (3, AZiNE (manufactured by Shikoku Kasei Kogyo Co., Ltd.) was used.

The electrochromic device constructed in this manner was left for 1000 hours under the same conditions as the conventional example at 60°C and 95% relative humidity, and its display performance was measured.
There was no effect on the contrast of the WO8 display pole.

At this time, the water content in the electrolyte only increased from 0.2% by weight to 0.9% by weight.

Example 2 As a counter electrode, poly(4,4',4'-)liphenylamine) was dispersed in ethanol, and an aqueous solution of carbon black and sodium polyacrylate was mixed therein to create a suspension. . After immersing carbon fibers in this solution, they were air-dried and further vacuum-dried at 180° C. for 2 hours to prepare a counter electrode. At this time, the lead wire from the carbon fiber was used by attaching a platinum wire with platinum paste. An EC element was produced using the counter electrode thus produced and in the same manner as in Example 1, and an EC element with excellent durability was also produced.

(Effects of the Invention) As explained above, according to the present invention, it is possible to obtain the effect that the durability is significantly improved without using the eighth electrode due to the fabrication.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of an electric chromic display element as an example of the present invention, FIG. 2 a is a cross-sectional view of a counter electrode used in the present invention, and FIG. 2 is a plan view of the counter electrode shown in FIG. 2 a. , FIG. 8 is a diagram showing the change in electrical quantity of the counter electrode used in the present invention and a conventional counter electrode depending on heat treatment time, FIG. 4 is a cross-sectional view of a conventional electrochromic display element, and FIG. FIG. 3 is a cross-sectional view of a conventional counter electrode. 1... Transparent substrate 2... Conductive transparent electrode 8... Insulating film 4... Back substrate 5... Counter electrode 6...
・Light scattering plate 7...Sealing resin with spacer or spacer 8・
...Sealing resin 9...Electrolyte solution 10...Triphenylamine polymer film 11...Lead wire for counter electrode 12...Conductive material for counter electrode 18...WOM [14...・Prussian blue film 1
5... Inlet. Patent applicant Nissan Motor Co., Ltd. Figure 1 Figure 2 (a) (b)

Claims (1)

[Claims] 1! 1. An electrochromic display element using a gas-vapor chemical oxidation photoreaction, characterized in that a conductive material formed of a triphenylamine polymer is used as a counter electrode.