JPS6360429A - Electrochromic display element - Google Patents

Abstract

PURPOSE:To permit extremely easy formation of counter electrode material layers at a low cost and to obtain an electrochromic display element which is excellent in surface characteristics such as quantity of the electricity to be implanted and response speed by forming the counter electrode material layers of the laminated structure consisting of a specific conductive layer and active material layer consisting of a specific tungsten oxide compd. deposited thereon. CONSTITUTION:The electrochromic material layer 3 is formed of tungsten trioxide. The counter electrode material layers 7a, 7b have the laminated structure in which the active material layer 21 consisting of the tungsten oxide compd. contg. H2O2 component and H2O component or these two components and CO2 component in the molecule is deposited on the conductive layer 20 contg. conductive particles and binder or a carbon fiber layer 22 provided on said layer. The surface characteristics such as the quantity of the electricity to be implanted and response speed are extremely improved by the excellent electrochemical activity specific to the tungsten oxide compd. coupled with the good conductive effect by the carbon fiber layer and the effect of increasing the specific surface area for reaction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an electrochromic display element that performs display on various display devices by utilizing color change caused by an electrochemical reaction of an electrochromic substance made of tungsten trioxide. .

[Prior art] This type of electrochromic display element has, for example, a third
As shown in the figure, an electrochromic material layer 3 made of tungsten trioxide is provided on the inner surface of a light-transmitting display substrate 1 via a transparent electrode layer 2, and the display is divided into segments constituting a required pattern. The pole is 4, and the opposite substrate is 5.
A counter electrode material layer 7 is provided on the inner surface of the electrode layer 6 via an electrode layer 6 to serve as a counter electrode 8, and both substrates 1 and 5 are arranged facing each other with a spacer 9 interposed in the periphery so that the electrodes 4 and 8 face each other. It has a structure in which an electrolytic solution 10 is sealed between the two electrodes 4 and 8. In the figure, 11 is the background material interposed between the poles 4 and 8, and 12
13 is a lead terminal, and 13 is a lead terminal 1 on the side opposite to the electrolytic layer 6.
A conductive layer 14 electrically connects 2 and 2, and 14 is an insulating protective film. Note that there is also a structure in which the electrode layer 6 of the counter electrode 8 is omitted by constructing the counter substrate 5 from a metal plate (
(Reference unknown).

In the display element with the above configuration, by applying a voltage to the required display electrodes 4 using the counter electrode 8 as a common electrode, the color changes due to the reaction between tungsten trioxide, which is an electrochromic material, and the counter electrode material via the electrolyte. and the required display is made. This color change is expressed by the following equation, for example, when the electrolyte of the electrolytic solution 10 is a lithium salt.

WO3+ nL++ne: LinW03 (transparent) (blue) By the way, the counter electrode material layer 7 of the counter electrode 8 has conventionally been made of tungsten trioxide deposited by a thin film forming method performed under high vacuum such as vacuum evaporation or sputtering. A single layer, a coating layer of a paint containing a counter electrode material such as tungsten trioxide, iron tungstate (Fe20.3WO,), manganese trioxide, a binder and a conductive powder, or a paint layer containing a conductive powder and a binder. Films in which activated carbon fibers are crimped onto a membrane layer are widely used (Japanese Unexamined Patent Publication Nos. 56-91222 and 57-68).
No. 26, No. 59-192282, etc.). In addition to these, for example, a layer containing rhenium or manganese may be formed using tungsten trioxide as a main ingredient by vacuum evaporation (Japanese Unexamined Patent Publication No. 54-41760), or a tungsten plate may be used as the opposing substrate to cover its surface. Oxidation (Japanese Unexamined Patent Publication No. 57-64282) has also been proposed.

[Problem that the invention seeks to solve]

However, in an electrochromic display element, it is desirable that the difference in potential between the display electrode and the counter electrode is small from the viewpoint of display characteristics, and from this point of view, the counter electrode material layer 7 should have the same potential as the electrochromic material layer 3. That is, a single layer of tungsten trioxide is preferable.

However, in order to form the above-mentioned single layer, it is necessary to adopt a thin film forming method such as vacuum evaporation or sputtering as described above, or a surface oxidation method of a tungsten plate as proposed above, but the former method requires equipment In addition, complex control operations and long processing times are required, resulting in poor workability and mass production, resulting in high costs.Especially when increasing the area of the counter electrode material layer as the device becomes larger, the cost increases. The disadvantages become more pronounced, and defects such as pinholes are more likely to occur, making it difficult to consistently obtain stable properties and characteristics. Furthermore, in the latter method, the substrate itself is very expensive, and it is difficult to control the oxide film thickness, so it is not practical.

The present invention was made in view of the above circumstances, and provides an electrochromic display element in which a counter electrode material layer can be formed extremely easily and at low cost, and which is also excellent in terms of display characteristics such as the amount of injected electricity and response speed. It is intended to.

[Means for solving problems]

In the process of intensive study to achieve the above object, the inventors found that when the counter electrode material layer is made of a tungsten oxide compound containing a specific component in the molecule, the counter electrode material layer is a solution of the tungsten oxide compound. It can be easily formed by dipping the substrate into the solution or by spin-coating the solution.
Moreover, the electrochromic display element is comparable in terms of display performance, such as the amount of injected electricity and response speed, compared to those having a counter electrode material layer consisting of a single layer of tungsten trioxide formed by conventional vacuum evaporation or sputtering. I discovered that.

As a result of further studies, it was found that when the counter electrode material layer has a specific conductivity and the active material layer made of the above specific tungsten oxide compound is deposited on top of the counter electrode material layer, the amount of injected electricity is The present inventors have discovered that the display performance, such as the display speed and response speed, can be further improved, and have come up with this invention.

That is, in the present invention, a pair of substrates that are transparent at least on the display side are arranged facing each other, and a display electrode consisting of a transparent electrode layer and an electrochromic material layer provided on the transparent electrode layer is formed on the inner surface of the display side substrate. In an electrochromic display element in which a counter electrode having a counter electrode material layer is formed on the inner surface of a counter substrate, and an electrolyte is sealed between these two electrodes, the electrochromic material layer is made of tungsten trioxide, and the counter electrode is The substance layer contains H2O2 components and H,O2 components in molecules on the surface of the conductive layer containing conductive particles and a binder or the carbon fiber layer provided on this layer.
The present invention relates to an electrochromic display element having a laminated structure formed by depositing an active material layer made of a tungsten oxide compound containing one or both of these components and a CO2 component.

[Structure and operation of the invention]

1 and 2 show an example of the structure of an electrochromic display element according to the present invention, and reference numeral 1 in the figures shows an example of the structure of an electrochromic display element according to the present invention.
6 and 8 to 13 have the same configuration as each part with the same reference numeral in FIG. 3 above.

First, in the display element of FIG. 1, the counter electrode material of the counter electrode 8 @
7 a is a conductive layer 20 containing conductive particles and a binder;
and an active material layer 21 made of the specific tungsten oxide compound deposited thereon. In the display element shown in FIG. 2, the counter electrode material layer 7b includes a conductive layer 20 similar to that shown in FIG. 1, a carbon fiber layer 22 provided thereon, and a carbon fiber layer 22 provided thereon similar to that shown in FIG. The active material layer 21 has a three-layer structure.

The tungsten oxide compound constituting the active material layer 21 of the counter electrode material layers 7a and 7b has H2O2 in its molecules as described above.
It may be either one containing the above-mentioned H20 component, or one containing the CO2 component together with both of the above components, and includes those containing various contents of each of these components, but in particular, those containing the following general formula; % formula % is 0.16 to Compounds in the range of 3.5 are preferred.

In order to form the active material layer 21 made of such a tungsten oxide compound, the tungsten oxide compound as a raw material is dissolved in alcohol such as isopropyl alcohol or water in a range of 0.1 to 5 y/ml, and this solution is dissolved. Therein, an electrode layer 6 and a conductive layer 20, or these layers 6.2
The opposite substrate 5 further has a carbon fiber layer 22 provided thereon in advance.
Alternatively, the solution may be spin-coded onto the conductive layer 1120 or the carbon fiber layer 22 of the opposing substrate 5, and then heat-treated at a temperature of about 100 to 300°C. In addition, when the carbon fiber layer 22 is provided, the above-mentioned dipping means is particularly suitable.

In addition, the tungsten oxide compound used as the above raw material is generally synthesized by the reaction of metallic tungsten or tungsten carbide with hydrogen peroxide. 0.05-1.0.2
is a compound in which the value is in the range of 0.16 to 4.0. In addition,
Since the H20 component contained in the tungsten oxide compound of this raw material is partially evaporated during the heat treatment during the formation of the active material layer 21, the value of 2 above is the preferable value of 2 in the tungsten oxide compound as the active material layer 21. is greater than the value.

The thickness of the active material layer 21 thus formed is 12O00 to 102 in both the configurations shown in FIG. 1 and FIG.
It is best to set it to about OOOA.

As the conductive powder contained in Conductivity@20, carbon black or fine metal powder can be used, but carbon black is preferable, especially those with a BET specific surface area of 100 to 2.
Carbon black of about 2000g/gt is optimal. Furthermore, as the binder for the conductive layer 20, epoxy resin, imidazole resin, etc. are preferably used. The amount of conductive powder to be used is preferably about 50 to 200 parts by weight per 100 parts by weight of the binder; if it is too small, the conductivity will decrease and the amount of electricity injected and the response characteristics of the display element will be affected. On the other hand, if the amount is too large, the binding force of the binder will be insufficient, making it difficult to form a layer.

In addition to the conductive powder and binder described above, counter electrode material powder such as tungsten trioxide, iron tungstate, manganese trioxide, etc. may be blended into the conductive layer 20 as necessary. The amount of such counter electrode material powder used is 1
It is preferable that the amount is 100 parts by weight or less per 00 parts by weight.

To form the conductive layer 20, conductive powder is applied onto the formed electrode layer 6 and dried, and then
The heat treatment may be performed at about 00°C.

The thickness of the conductive layer 20 thus formed is preferably about 0.5 to 100 P in both the configurations shown in FIG. 1 and FIG. 2.

The carbon fiber layer 22 used in the device configuration of FIG. 2 is made of ordinary carbon fiber or activated carbon fiber and has a thickness of 0.5 mm.
A woven fabric of about 1 to 0.5 fl is preferably used, and generally this woven fabric is placed on the conductive @ 20 formed previously.
It is provided on the conductive layer 20h by pressing at a pressure of about 0 to 500 y/cd.

In such a counter electrode material layer 7 a + 7 b, the above-described tungsten oxide compound constituting the upper active material layer 21 has a composition similar to that of tungsten trioxide, which is the electrochromic material of the display electrode 4, and has approximately the same potential. The lower conductive layer 20 exhibits excellent electrochemical activity.
Alternatively, this and the carbon fiber layer 22 exhibit good electrical conductivity, and a large amount of the electrically conductive powder or this and the carbon fibers serve to significantly increase the reaction specific surface area.

Therefore, in the display element having the configurations of FIGS. 1 and 2 having the counter electrode material layers 7a and 7b, that is, the display element of the present invention, the conventional counter electrode material layer is a coating film layer containing a counter electrode material, a conductive powder, and a binder. It has better display characteristics such as the amount of electricity injected and response speed compared to those that are made of a coating layer containing conductive powder and a binder, and those that are made of activated carbon fibers bonded to a coating layer containing conductive powder and a binder, and those that are made of a vapor-deposited layer of tungsten trioxide. In addition, the display characteristics are also better than those in which the counter electrode material layer is composed only of the tungsten oxide compound. In particular, the display element having the structure shown in FIG. 2 having the carbon fiber layer 22 has the advantage that the amount of injected electricity does not decrease even after long-term use and is excellent in durability.

Note that a glass plate, a ceramic plate, or the like is used as the opposite substrate 5, and the conductive layer 6 on the surface thereof is formed by vapor-depositing a transparent electrode film such as an indium-tin composite oxide film (hereinafter referred to as an ITO film), or It is formed by pressing a foil-like material such as gold or platinum. Note that instead of the substrate provided with such a conductive layer 6, a metal plate made of AI, Ni, Cu%Ti, or the like may be used.

On the other hand, the display electrode 4 has the same structure as the conventional one, in which a transparent electrode layer 2 made of an ITO film or the like is formed by vapor deposition on one surface of the display side substrate 1 made of a transparent material such as glass, and a transparent electrode layer 2 made of an ITO film or the like is formed on this by vacuum vapor deposition. The electrochromic material layer 3 may be formed by depositing tungsten trioxide to a thickness of about 22000 to 62000A using a thin film forming method such as sputtering.

As the electrolytic solution 10, a solution in which a lithium salt such as L + C104 is dissolved in a non-aqueous solvent such as propylene carbonate, or a solution in which a small amount of water is added is generally used. The background material 11 hides the opposing electrode 8 and uses its own color tone as the background color of the display, and is made of a sheet-shaped molded mixture of a pigment such as titanium trioxide and polytetrafluoroethylene powder. Alternatively, a gel body of the pigment and the electrolytic solution 10 is applied and formed on the counter electrode 8 by screen printing or the like.

[Effects of the Invention] In the electrochromic display element according to the present invention, the electrochromic material layer of the display electrode is made of tungsten trioxide, and the counter material layer of the counter electrode is a conductive layer containing conductive powder or a conductive layer formed thereon. Since it has a laminated structure in which an active material layer made of a tungsten oxide compound containing a specific component in the molecule is deposited on the surface of the provided carbon fiber layer, it has the excellent electrochemical activity unique to the above-mentioned tungsten oxide compound. , the above conductive layer or this and the carbon Y4 fiber layer combine to provide good conductivity and increase the reaction specific surface area, resulting in extremely excellent display characteristics such as the amount of electricity injected and the response speed. Since it can be formed by immersing a substrate in a tungsten solution or by spin-coating the solution, the entire counter electrode material layer can be formed using vacuum evaporation or sputtering, which requires large-scale equipment, complicated control operations, and long processing times. It has the advantage that a uniform product can be formed easily and at low cost by a general coating method that can simultaneously process a large amount without using a layer forming method.

〔Example〕

Hereinafter, this invention will be specifically explained based on examples.

Example 1 A counter plate substrate made of transparent glass (vertical 25 mm) on which an electrode layer of ITO film with a thickness of 22 OOOA was vapor-deposited in advance on one side.
m, width 180fi, thickness 1.1 tg), the following composition was applied: Phthalic anhydride 18 parts by weight Methyl isobutyl ketone 30 parts by weight Toluene
After applying a paint consisting of 30 parts by weight so that the thickness after drying is 10/'I, and drying,
A conductive layer was formed by heat treatment at 150° C. for 2 hours.

Next, this opposite substrate is formed so that X in the general formula is 0.0.
8 to 0.25, y is 0.05 to 1. An active material layer with a thickness of 22OOOA is formed on the conductive layer by immersing it in a solution dissolved at a concentration of 59/me, drying it, and then heating it at 120°C for 20 minutes. A counter electrode material layer was formed. Analysis of this active material layer revealed that X in the general formula is O, OS~
0.25, y is 0.05-1.0.2 is 0.16-3.
5, a tungsten oxide compound.

On the other hand, a transparent electrode layer with a predetermined pattern made of an ITO film with a thickness of 22OOOA and an S with a thickness of 5.00OA are placed on one side in advance.
i O, display side substrate made of transparent glass with a protective film deposited (length 27H1 width 185fl, thickness 1.1 tax)
On the transparent electrode, tungsten trioxide is vacuum-deposited using a photoresist mask to form an electrochromic material layer in a predetermined pattern with a thickness of 5°000A,
The display pole was constructed.

Then, the above-mentioned two substrates are arranged facing each other with the display electrode and the counter electrode facing each other with a rectangular annular spacer made of polyester resin having a thickness of 1 layer interposed in the peripheral part, and are fixed with adhesive. In between, 0 thickness consisting of 100 parts by weight of titanium oxide and 100 parts by weight of polytetrafluoroethylene.
．． An electrochromic display element having the structure shown in FIG. 1 was prepared by sandwiching a 3W sheet-like background material and sealing therein an electrolytic solution 5d made of propylene carbonate in which 1 molar concentration of LiC10 was dissolved. .

Example 2 Electrochromatography was carried out in the same manner as in Example 1, except that the raw material tungsten oxide compound used was one in which X in the general formula is 0, y is 0.05 to 1, and 0.2 is 3 to 4. A mink display element was fabricated. Note that in the tungsten oxide compound of the counter electrode material layer of this element, X in the general formula is O, y
is 0.05 to 1. OlZ was 0.16-3.5.

Example 3 A solution prepared by dissolving the same raw material tungsten oxide compound as in Example 1 in water at a concentration of 19'/me was spin-coated onto the conductive layer of the opposing substrate at a rotational speed of 3.00 rpm.
After drying, an electrochromic display element was produced in the same manner as in Example 1, except that a heat treatment was performed at 120° C. for 60 minutes to form an active material layer with a thickness of 32OOOA.

In the tungsten oxide compound of this active material layer, in the general formula, X is 0.08 to 0.25 and y is 0.05 to 1.0%Z.
was 0.16 to 3.5.

Example 4 A coating layer with a thickness of 0.0 mm was applied to the surface of the coating layer before drying to form a conductive layer.
Activated carbon fiber cloth (Toyobo Co., Ltd. product name #800)
) was placed and pressed with a pressure of 50 y/cat to adhere it, then dried and heat-treated at 250°C for 2 hours to form a conductive layer and a carbon fiber layer. The second step was carried out in the same manner as in Example 1 except that the active material layer was formed.
An electrochromic display element having the structure shown in the figure was manufactured.

Example 5 X in the above general formula as a raw material tungsten oxide compound
An electrochromic display element was produced in the same manner as in Example 4, except that a material having o and y of 0.05 to 1.0.2 was 3 to 4 was used.

Comparative Example 1 Acetylene black (same as Example 1) 25 parts by weight Tungsten bolide powder 25 parts by weight Epoxy resin (same as Example 1) 35 parts by weight Phthalate anhydride 15 parts by weight Methyl in butyl ketone 30 parts by weight Torr en
30 parts by weight of the paint having the above composition is applied onto the electrode layer of the opposite substrate so that the thickness after drying is 10/'', and after drying, heat treatment is performed at 150°C for 2 hours to form a counter electrode material layer. An electrochromic display element was produced in the same manner as in Example 1 except that .

Comparative Example 2 An electrochromic display element was produced in the same manner as in Example 4, except that the active material layer made of a tungsten oxide compound was not provided.

Comparative Example 3 An electrochromic display element was produced in the same manner as in Example 1, except that the counter electrode material layer was composed only of a layer having a thickness of 52 OOOA formed by vacuum evaporation of tungsten trioxide.

Comparative Example 4 An electrochromic display element was produced in the same manner as in Example 1, except that the counter electrode material layer was composed only of an active material layer made of a tungsten oxide compound without forming a conductive layer. 9 Above Examples and Comparative Examples For each display element, ±1.
A pulse voltage of 2V and IHz was applied to drive the vehicle, and the amount of electricity injected was measured at the initial stage of driving, after 3X105 times, and after IX10' times, and +1.2V of electricity was applied.
The response speed expressed as the time until the display disappeared when pressure was applied was measured. These results are shown in the table below.

As is clear from the results in the above table, the electrochromic of the present invention has a counter electrode material layer having a laminated structure of an active material layer made of a tungsten oxide compound containing a specific component in the molecule and a conductive layer or a carbon fiber layer. The display elements (Examples 1 to 5) include a display element having a counter electrode material layer with a conventional structure (Comparative Examples 1 to 3) and a display element in which the counter electrode material layer is composed of only the above active material layer (Comparative Example 4). It can be seen that in all cases, the amount of electricity injected is large (and the response speed is fast, and the display characteristics are excellent. , 5) shows very little decrease in the amount of injected electricity even when driven many times, and is found to have excellent durability and long life.

[Brief explanation of drawings]

FIGS. 1 and 2 are longitudinal cross-sectional views of essential parts showing an example of the structure of an electrochromic display element according to the present invention, and FIG. 3 is a longitudinal cross-sectional view of an example of the structure of a conventional electrochromic display element. DESCRIPTION OF SYMBOLS 1... Display side substrate, 3... Electrochromic material layer, 4... Display electrode, 5... Opposite side substrate, 7 a
+ 7 b... Counter electrode material layer, 8... Counter electrode, 10.
... Electrolyte solution, 20 ... Conductive layer, 21 ... Active material layer,
22...carbon fiber layer

Claims (2)

[Claims] (1) A pair of substrates whose display sides are translucent are arranged facing each other, and a display electrode consisting of a transparent electrode layer and an electrochromic material layer provided thereon is formed on the inner surface of the display side substrate, and In an electrochromic display element in which a counter electrode having a counter electrode material layer is formed on the inner surface of a side substrate, and an electrolyte is sealed between these two electrodes, the electrochromic material layer is made of tungsten trioxide, and the counter electrode material layer is made of tungsten trioxide. The layer is a conductive layer containing conductive particles and a binder, or a carbon fiber layer provided on this layer. An electrochromic display element characterized by having a laminated structure formed by depositing material layers. (2) The tungsten oxide compound has the following general formula; WO_3
・x expressed as xCO_2・yH_2O_2・zH_2O, where x is 0 to 0.25, y is 0.05 to 1.0, and z is 0.
16 to 3.5. The electrochromic display element according to claim 1, wherein the electrochromic display element is a compound having a molecular weight of 16 to 3.5.