JPS63267918A - Electrochromic display element - Google Patents

Abstract

PURPOSE:To obtain the excellent responsibility and durability of the titled element by preventing the deterioration of the element due to a secular use by using a metal plate for a substrate at a counter side, and by uniting said metal plate with a counter electrode, and by arranging the inner surface of the substrate so as not to make in contact with an electrolyte. CONSTITUTION:The counter pole 7 is constituted by the metallic substrate 5 united the counter electrode and a counter pole material layer 6 contg. an electrically conductive plastic layer 6a which is formed on the inner surface of the plate 5. The contact between said substrate 5 and the electrolyte 9 is cut off by extending said plastic layer 6a to the inner circumference of a spacer 8 or by providing with a nonconductive plastic layer 10 buried between the layer 6a and the inner circumference of the spacer 8. Thus, the surface resistivity of the counter electrode due to the excellent conductivity of said substrate 5 is reduced, thereby improving the responsibility, and the corrosion of the substrate 5 caused by the electrolyte is prevented, thereby improving the durability of the titled element.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrochromic display element used in various displays and the like.

[Conventional technology]

A typical example of this type of display element is a display in which a layer of electrochromic material is provided on the inner surface of a translucent display substrate via display electrodes, dividing the display into segments constituting a required pattern. An electrochromic device has a structure in which an electrolytic solution is sealed between the two electrodes of the side substrates, which are arranged facing each other with a frame-shaped spacer in between. Display elements are known. In this display element, as the display electrode and the counter electrode, a transparent conductive film made of a composite oxide of indium and tin (hereinafter referred to as ITO), which has corrosion resistance against electrolyte, is generally used. has been done.

In such a display element, by applying a voltage to required segments of the display electrode using the counter electrode as a common electrode, a reversible redox reaction between the electrochromic material and the counter electrode material via the electrolyte can be caused. A predetermined display is performed on the display-side substrate by changing the color of the substance.

By the way, the response characteristics of such a display element are generally better as the amount of injected electricity is larger, but this amount of injected electricity depends on the electrical resistance of the display electrode and the counter electrode. In particular, since a large current flows through the counter electrode, which serves as a common electrode, the sheet resistance value of that electrode greatly influences the response characteristics of the element, and this tendency becomes more pronounced as the element becomes larger. Become.

[Problem that the invention seeks to solve]

However, ITO or the like used as the transparent conductive film described above tends to lack conductivity to some extent, resulting in the disadvantage that the sheet resistance of the counter electrode inevitably increases, which makes it difficult to obtain a large amount of injected electricity. .

Therefore, it is possible to use metal for the counter electrode in order to lower the sheet resistance value of the counter electrode, but precious metals such as gold and platinum are extremely expensive, so they are not used from a cost perspective. Common metals, which are difficult and inexpensive, have poor corrosion resistance against electrolytes, and in particular, have a problem in that the amount of electricity injected during the coloring/decoloring cycle test decreases significantly, resulting in poor durability.

Therefore, the present invention aims to solve the above problems;
In other words, the object of the present invention is to provide an electrochromic display element that has a counter electrode that has a low sheet resistance, is not easily deteriorated even after long-term use, and has excellent response characteristics and durability.

[Means for solving problems]

As a result of intensive studies to achieve the above object, the inventors constructed a counter substrate of metal, made this substrate itself play the role of a counter electrode, and therefore formed a counter electrode material layer directly on the substrate. On the other hand, since this counter electrode material layer is usually provided in a small size corresponding to the display electrode, the side edge of the substrate is exposed, and when this comes into contact with the electrolyte, the problem of corrosion resistance as described above may occur. However, in order to solve this problem, if a specific means is added to prevent the above-mentioned exposed portion from occurring, the amount of electricity injected is large and the deterioration of the counter electrode is extremely small even after long-term use. The inventors discovered that it is possible to obtain an electrochromic display element with excellent response characteristics and durability, and came up with the present invention.

That is, the present invention provides an electrochromic display element in which a display electrode and a counter electrode are arranged opposite to each other with a frame-shaped spacer interposed therebetween, and an electrolyte is sealed therein, and the above-mentioned counter electrode also serves as a counter electrode. and a counter electrode material layer including a conductive plastic layer formed on the inner surface thereof, and the conductive plastic layer extends to the inner periphery of the spacer, or the conductive plastic layer and the spacer This relates to an electrochromic display element in which a non-conductive plastic layer is provided on the substrate to fill the space between the metal substrate and the electrolytic solution, thereby blocking contact between the metal substrate and the electrolyte.

[Structure and operation of the invention]

The present invention will be explained below with reference to the drawings.

FIG. 1 shows an example of the structure of an electrochromic display element according to the present invention.

In the figure, 1 is a transparent display-side substrate made of a glass plate, etc., and 2 is a transparent conductive film such as ITO formed on the inner surface of the substrate 1 by vacuum evaporation or sputtering. ,oo.

The surface electrode 3 has a thickness of approximately 3,000 yen, and the electrochromic material layer 4 has a thickness of tungsten oxide thin film formed on the surface of the electrode by a method similar to that described above, and is normally approximately 3,000 to 10,000 yen thick. This is a display pole divided into segments constituting a required pattern consisting of.

5 is a metal substrate on the counter-same pole side that also serves as a counter electrode,
A counter electrode material layer 6 consisting of a conductive plastic layer 6a and a cross-like substance 6b such as carbon fiber or activated carbon fiber bonded via this layer 6a is formed on the inner surface of this substrate 5, thereby forming a counter electrode 7. has been done.

The counter electrode 7 and the display electrode 2 are arranged to face each other with a frame-shaped spacer 8 interposed therebetween, and a lithium salt such as LiCff04 is added to a non-aqueous solvent such as propylene carbonate inside the counter electrode 7 and the display electrode 2 with a frame-shaped spacer 8 in between. A dissolved electrolytic solution 9 is enclosed. 10 is the above opposing pole 7
This is a non-conductive plastic layer that fills between the conductive plastic layer 6a, which is a component of the counter electrode material layer 6, and the inner periphery of the frame-shaped spacer 8. contact is completely cut off.

Note that 11 is an insulating protective layer made of 5i02 or the like for protecting the display electrode 3 in the display electrode 2, and 12 is the counter electrode 7.
and the display electrode 2 , and 13 is the display electrode 2 connected to the side edge of the display substrate 1 .
14 is a lead terminal of the opposite electrode 7 connected to the same side edge, and 15 is a conductive layer made of conductive paste or the like that connects the lead terminal 14 and the opposite electrode 7.

In such a configuration, the material of the metal substrate 5 is not particularly limited as long as it has good conductivity, but stainless steel plates, Al plates, Ni plates, etc. are preferable. . The thickness of the metal substrate 5 is approximately 0.05 to 2 fl; if this thickness is too thin, the substrate may lack mechanical strength or the electrical resistance as a counter electrode may be sufficiently reduced. This is not desirable because it becomes difficult.

Further, the counter electrode material layer 6, which is formed of the conductive plastic layer 6a and the cross-shaped material 6b provided on the metal substrate 5, contains conductive particles such as carbon powder and a plastic binder such as epoxy resin. After applying an adhesive paste-like material to a thickness of about 10-100 μm, a layer of carbon fiber or activated carbon fiber is usually applied on top of this to a thickness of 0.1-100 μm.
It is formed by bonding together approximately 1 fl of cross-shaped materials and heating and curing them.

Further, the non-conductive plastic layer 10 may be made of any thermosetting resin or thermoplastic resin as long as it can effectively protect the metal substrate 5 from corrosion by the electrolyte. In this example, an adhesive paste for forming the conductive plastic layer 6a from which conductive particles have been removed, that is, a normal epoxy resin composition, is used to form the counter electrode material layer 6. The figure shows a product formed by injecting and curing after formation.

The thickness of this non-conductive plastic layer IO is generally about 10 to 200 μm.

In the electrochromic display element having the above configuration,
When no voltage is applied between the display electrode 3 and the metal substrate 5 which also serves as a counter electrode, there is no reaction between the electrochromic material layer 4 and the counter electrode material layer 6 via the electrolyte 9, and no reaction occurs from the display side substrate 1. The background color of the background material 12, for example white, can be seen through. On the other hand, if a voltage is applied to both the electrodes 3 and 5, the reactant is colored, for example, blue. A pattern is displayed on the display side substrate l.

Here, since a metal plate is used as the opposing substrate and the metal substrate 5 also serves as the opposing electrode,
Due to the excellent conductivity of the metal plate 5, the sheet resistance of the counter electrode is reduced, a large amount of electricity can be injected, and the response characteristics can be improved. Further, on the exposed surface of the inner surface of the metal substrate 5 that does not have the counter electrode material layer 6, that is, between the conductive plastic layer 6a of the layer 6 and the inner periphery of the frame-shaped spacer 8, the non-conductive plastic layer described above is provided. 10 prevents the metal substrate 5 from being corroded by the electrolyte, making it resistant to deterioration even after long-term use and having excellent durability.

Next, FIG. 2 shows a modification of the counter electrode material layer 6 and the non-conductive plastic layer 10 in the electrochromic display element having the above structure. Board 5
A non-conductive plastic layer lo is formed by heat-sealing it to the side edge of the electrode, and the inside thereof contains conductive particles such as carbon powder (which also serves as a counter electrode active material) and a plastic binder such as an epoxy resin. An adhesive paste-like material, that is, a paste-like material similar to that used in forming the conductive plastic layer 6a described above, or a composition prepared by adding a counter electrode active material such as iron tungstate or manganese dioxide to a thickness of about 10 to 500 μm. The counter electrode material layer 6 consisting of the conductive plastic layer 6a alone is formed by applying the material to a thickness of 1 and curing the conductive plastic layer 6a. It goes without saying that the same effects as described above can also be achieved in this embodiment.

Moreover, FIGS. 3 and 4 show still another modification, in which instead of forming the non-conductive plastic layer 10, the conductive plastic layer 6a constituting the counter electrode material layer 6 is formed using a frame-shaped spacer. By extending to the inner periphery of the plastic layer 8, the same effect as the plastic layer 10 described above can be achieved. That is, in FIG. 3, the conductive plastic layer 6a of the counter electrode material layer 6 having the structure shown in FIG. 1 extends to the inner periphery of the spacer 8, and in FIG. Durability can be improved by extending the counter electrode material layer 6 consisting of the conductive plastic layer 6a alone in the same manner as above, and blocking contact between the electrolytic solution 9 and the metal substrate 5 by these extensions 100. .

In addition, in the above configuration example, an example in which an electrolytic solution 9 made by dissolving a lithium salt as an electrolyte in a non-aqueous solvent is used, but this electrolytic solution 9 may be an aqueous solution such as an aqueous sulfuric acid solution. The metal substrate 5 can be selected and used depending on the type of the electrolytic solution 9. In addition to the tungsten oxide mentioned above, various known materials can be used as the electrochromic material layer 4, and colored display can be performed depending on the type of the material.

[Effects of the Invention] As described above, according to the present invention, a metal plate is used as the opposite substrate, and this metal substrate also serves as a counter electrode, and the inner surface of this substrate does not come into contact with the electrolyte. By adopting the specific configuration, it is possible to provide an electrochromic display element that has a low sheet resistance of the counter electrode, is resistant to deterioration even after long-term use, and has excellent response characteristics and durability.

〔Example〕

EXAMPLES Below, examples of the present invention will be described in more detail.

Example 1 It has been thoroughly cleaned and has a length of 38 fi and a width of 67 fl.

On the inner surface of a transparent glass plate with a thickness of 1.1 fl,
A display electrode made of ITO with a thickness of 5,000 yen and an electrochromic material layer made of a thin film of tungsten oxide with a thickness of 5,000 yen were each formed on the display electrode by vacuum evaporation to form a display electrode in a predetermined pattern. . In addition, S is added to the surface of the display electrode other than the electrochromic material layer.
An insulating layer having a thickness of 1,000 wafers was formed by vacuum deposition of iOz.

On the other hand, vertical 331. 5US3 with width 69N and thickness 0.2w
On the inner surface of the substrate consisting of 04, a 4 liter portion from the side edge is left in the shape of a frame and an adhesive conductive paste [trade name RP-10 manufactured by Tokurikisha Co., Ltd.; contains epoxy resin and carbon powder] Paste] was applied to a thickness of 20 μm by screen printing, and then 25 cranes (length), 60 fi (width), and a thickness of 0.
5 Tsuru activated carbon fiber cloth (product name CH- manufactured by Kuraray Co., Ltd.)
20) were bonded together, and then heat-cured at 200° C. for 1 hour to form a counter electrode material layer, thereby forming a counter electrode.

Then, the above-mentioned side substrate is arranged so that the display electrode and the counter electrode face each other, and a mixture of titanium dioxide pigment and polytetrafluoroethylene powder is applied between the two electrodes to a thickness of 300 I! A background material consisting of a sheet-shaped molded product (trade name: Boa-Fron, manufactured by Sumitomo Denki Kogyo Co., Ltd.) of 1.5 mm is interposed, and a rectangular frame-shaped spacer made of polyester with a thickness of 1 fi is inserted in the periphery and placed facing each other. It was fixed with resin adhesive.

In addition, prior to this adhesive fixation, a mixture of an epoxy resin (trade name Epicoat #828 manufactured by Yuka Shell Co., Ltd.) and a curing agent (trade name Persamide 140 manufactured by Henkel Co., Ltd.) in a weight ratio of 100 to 5 was applied to the opposing substrate. 10 into the inner surface of the side edge where there is no counter electrode material layer, that is, between the conductive plastic layer of the counter electrode material layer and the spacer.
A heat treatment was performed at 0° C. for 2 hours to form a non-conductive plastic layer on the side edges.

After that, an electrolytic solution in which 1 mol of lithium perchlorate is dissolved in propylene carbonate is sealed, and the lead terminal on the display electrode side is connected to the edge of the substrate on the display electrode side, and then the lead terminal on the opposite electrode side is connected to the edge of the substrate on the display electrode side. An electrochromic display element of the present invention having the configuration shown in FIG. 1 was manufactured by connecting the electrode to the edge of the substrate on the display electrode side via a conductive paste.

Example 2 Formation of a non-conductive plastic layer
A rectangular frame-shaped polyamide film (product name Diaamide Film #7000 manufactured by Daicel Corporation) with inner dimensions of 25 x 60 mm and thickness of 25 μm is used, and the metal is placed so that its outer periphery is pressed against the inner periphery of the rectangular frame-shaped spacer. Provided on the board 2
kg/cd, 250°C for 1 second, and after forming this non-conductive plastic layer, iron tungstate (Fe (WO
4) A mixture of 3) and an adhesive conductive paste (product name RP-10 manufactured by Tokurikisha; paste containing epoxy resin and carbon powder) in a weight ratio of 1:1 was screen printed to a thickness of 200 μm. An electrochromic display element of the present invention having the structure shown in FIG. 2 was produced in the same manner as in Example 1, except that a counter electrode material layer was formed by coating and heating at 150° C. for 5 hours.

Example 3 Instead of forming a non-conductive plastic layer, when forming a counter electrode material layer, the application of an adhesive conductive paste to the substrate surface was spread to a position where it touched the inner periphery of a rectangular frame-shaped spacer. Example 1 except that the conductive plastic layer formed by the subsequent heat curing treatment had an extending portion that contacted the spacer.
An electrochromic display element of the present invention having the structure shown in FIG. 3 was produced in the same manner as in the above.

Example 4 Instead of forming a non-conductive plastic layer, a mixture of iron tungstate and adhesive conductive paste was applied at a position in contact with the inner periphery of a rectangular frame-shaped spacer when forming a counter electrode material layer. The same as in Example 2 except that the counter electrode material layer made of a conductive plastic layer alone formed by a subsequent heat curing treatment had an extending portion that contacted the spacer. An electrochromic display device of the present invention having the configuration shown in FIG. 4 was prepared.

Comparative Example 1 An electrochromic display element was produced in the same manner as in Example 1 except that the non-conductive plastic layer was not provided.

Comparative Example 2 A glass substrate of the same size as the 5US304 substrate was used as the opposite substrate, and a counter electrode made of ITO with a sheet resistance of 7 Ω/hole was formed on the inner surface of the glass substrate. Do not form a conductive plastic layer.
The procedure was the same as in Example 2, except that a counter electrode material layer having approximately the same size as in Example 2 was formed (however, the heating conditions after coating to form the counter electrode material layer were 200° C. and 200° C.).
An electrochromic display device was fabricated.

The amount of electricity injected and the durability of each of the display elements of Examples 1 to 4 and Comparative Examples 1 and 2 were investigated, and the results were as shown in the table below.

・The amount of electricity injected is the same as in Example 1.3 and Comparative Example 1.
In Example 2, under the conditions of ±1.20V and 0.5 seconds,
4 and Comparative Example 2, the amount of electricity flowing when driven under the conditions of ±1.65 V and 0.5 seconds was measured.

In addition, durability was determined by conducting a coloring/decoloring cycle test under the same driving conditions as described above, and determining the number of cycles at which 90% or more of the initial amount of electricity was maintained.

As is clear from the above table, the electrochromic display element of the present invention is found to be highly satisfactory in both response characteristics and durability.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing an example of the electrochromic display element of the present invention, and FIGS. 2, 3, and 4 are cross-sectional views showing modified examples of essential parts of the display element. 2... Display electrode, 5... Metal substrate (counter electrode), 6
... Counter electrode material layer, 6a... Conductive plastic layer,
7... Opposing electrode, 8... Frame-shaped spacer, 9... Electrolyte, 10... Non-conductive plastic layer, 100...
extension part

Claims (1)

[Claims] (1) In an electrochromic display element in which a display electrode and a counter electrode are arranged facing each other with a frame-shaped spacer interposed therebetween and an electrolyte is sealed inside, the above-mentioned counter electrode is a metal substrate that also serves as the counter electrode, and its inner surface. and a counter electrode material layer including a conductive plastic layer formed on the spacer, and the conductive plastic layer extends to the inner periphery of the spacer, or the conductive plastic layer and the inner periphery of the spacer An electrochromic display element in which a non-conductive plastic layer is provided on the substrate to fill the space between the metal substrate and the electrolyte to block contact between the metal substrate and the electrolyte.