JPH0518737Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to an electrochromic (hereinafter abbreviated as EC) display cell, which is a display element that reversibly colors and decolors using an electrochemical redox reaction. It is.

[Conventional technology]

Previously proposed NESA (SnO ₂ ) films, ITO
EC display cells, in which an EC film is formed on a transparent conductive film such as (SnO ₂ , In ₂ O ₃ ) and used as a display electrode, are small, so there is little voltage drop across the conductive film itself when coloring or decoloring.
There were no problems in terms of response time or other characteristics.

However, when it comes to large EC display cells, such as those measuring 400 mm square or more, the response time of the conventional conductive film alone takes nearly an hour, making it impossible to put it to practical use.

[Problem to be solved]

When EC display cells are applied to buildings, vehicles, etc., it is necessary to make them larger and lighter. In other words, to reduce the amount of electrolyte, the cell spacing should be small (for example, 1
mm or less) is required. As cells become larger, the resistance of transparent conductive films alone is usually relatively high, as indicated by a surface resistivity of 5 to 50 Ω/hole, resulting in problems such as large voltage drops and excessive response speeds. . The present invention solves this problem by providing a bus bar on the transparent conductive film, but since the cell spacing is small as mentioned above, we have devised some ingenuity in this respect as well.
This is accomplished by the following means:

[Means for solving problems]

The EC display cell of the present invention has EC layers that are formed on a transparent conductive film, leaving the outer periphery, and are discolored and discolored, and are arranged facing each other, and each serves as a display electrode and a counter electrode.
In the EC display cell, a bus bar having a structure in which a conductive paste is baked and embossed copper foil is pasted on the conductive layer is provided on the outer periphery of the conductive film where the EC layer is not formed, and the bus bar portion is sealed. It is characterized by the following.

Further, even when using a counter electrode in which a counter electrode material is formed on a transparent conductive film, it is of course preferable to provide a bus bar on the outer periphery of the conductive film.

[Effect]

The EC layer formed on the transparent conductive film serves as the display electrode.
When the EC display cell becomes large, for example, 400 mm square or more, the resistance of the conductive film is relatively high as mentioned above, so the voltage drop due to the resistance becomes large and it is not practical. By providing it in the area, the voltage drop becomes smaller, the current flowing over the entire surface becomes more uniform, color unevenness during coloring/decoloring disappears quickly, and response time can be shortened.

Furthermore, since the spacing between the EC display cells is required to be very narrow, the thickness of the bus bar housed therein must also be as thin as possible. A metal foil such as copper may be considered as such a thin conductive material, but it is difficult to bring it into complete contact with the conductive film, and although the response time can be shortened, the current distribution varies, which is not the best.

The best structure is one in which embossed copper foil is pasted on a conductive layer formed by baking a conductive paste, which has lower resistance than copper foil alone, and is formed by baking a transparent conductive film-conductive paste. This serves to ensure sufficient adhesion between the conductive layer and the copper foil and to make the current distribution uniform.

〔Example〕

Hereinafter, the present invention will be explained in detail with reference to the drawings.

Figure 1 is a cross-sectional view showing the EC display cell of the present invention.
FIG. 2 is a plan view of a WO ₃ film and a bus bar formed on Nesa glass.

Example 1 1, 1 is a 400 mm square Nesa glass having transparent conductive films 2, 2. On one side, a WO 3 film was formed by vapor deposition as a display electrode 3, leaving the outer peripheral part on the transparent conductive film, and on the other side, a WO ₃ film was formed by vapor deposition. , the chemical formula as the counter electrode 4
A Prussian blue film represented by Fe ₄ 〓 [Fe 〓 (CN) ₆ 〕 _{3 ]} was formed by an electrolytic synthesis method, and a WO ₃ film on these conductive films and 10 mm from the edge where the Prussian blue film was not formed were formed. A conductive paste containing silver was applied to the outer periphery to a width of 2.5 mm and a thickness of 30 μm, heated at 100°C for 90 minutes, dried to form a conductive layer 5, and embossed on top (1.5 mm).
(with pitched surface irregularities) width 2.5mm, thickness 35μm
The copper foil 6 was pasted on with an adhesive vinyl tape 7 having a width of 5 mm so as to completely cover the conductive layer 5 as well.

Next, these Nesa glasses 1 and 1 were placed at a distance of 1 mm.
Seal with sealing material 8 so that the electrolyte 9
An EC display cell was prepared by injecting a propylene carbonate solution containing 1 mol/LiClO ₄ . In this case, when both WO ₃ and Prussian blue films are coated, they are both in an electrochemically oxidized state (WO ₃ : colorless, Prussian blue: blue), and coloring/decoloring drive is not possible. It needs to be in a state of return. In this example, a Prussian blue film was used after being reduced (initial decolorization) by a conventional method.

When a DC voltage of -1 V was applied between the display electrode and the counter electrode of the EC display cell thus obtained, the entire surface was colored uniformly and clearly in blue within 2 minutes.

Next, when +0.5V DC voltage was applied, 1
The entire surface was completely discolored within minutes and became a highly transparent body with visible light transmittance of 80%.

Example 2 An EC display cell was fabricated in the same manner as in Example 1, except that a copper foil with a width of 2.5 mm and a thickness of 35 μm was attached to the same outer periphery of the conductive film as in Example 1, and completely covered with an adhesive vinyl tape with a width of 5 mm.

The time required for coloring and decoloring this display cell was 10 minutes for coloring and 5 minutes for decoloring using the same driving voltage as in Example 1.

Example 3 An EC display cell was fabricated with the same configuration as in Example 1, except that the bus bar was a conductive layer formed by baking Ag paste under the same conditions on the conductive film at the same outer peripheral portion as in Example 1.

The time required for coloring and decoloring this cell was 30 minutes for coloring and 15 minutes for decoloring at the same driving voltage as in Example 1.

Comparative Example An EC display cell was manufactured with the same configuration as in Example 1 except that no bus bar was provided.

The time required for coloring and decoloring this cell was 60 minutes for coloring and 30 minutes for decoloring, which was much longer than the cell of Example. Moreover, the driving voltage is -1.5V for coloring, +1.5V for decoloring.
At 1.0V, a higher voltage was required than that of each example.

Note that the present invention is not limited to the embodiments, and can be applied in various ways.

EC materials used as display electrodes are formed on transparent conductive films such as SnO ₂ and In ₂ O _3. In addition to WO ₃ , EC materials such as MoO ₃ , NiOOH, Nb ₂ O ₅ , V ₂ O ₅ iridium oxide, etc. It may be a transition metal oxide, an iron cyanide complex such as Prussian blue, or a polymer thin film such as pyrrole, thiophene, or triphenylamine.

The material for the counter electrode may be any material that can reversibly perform a reduction-oxidation reaction that is completely opposite to the redox reaction of the display electrode, and can be used as a display material.
When using reduction coloring materials such as WO ₃ and MoO ₃ ,
Counter materials include iridium oxide, NiOOH,
Oxidative color-forming materials such as Prussian blue and polytriphenylamine may be selected from reduction color-forming materials when oxidative color-forming materials are used in the display electrode, but these counter electrode materials usually need to be provided on a transparent conductive film. Therefore, when the cell becomes large, it is better to provide the bus bar according to the present invention not only on the display electrode side but also on the counter electrode side. Simply Al as the counter electrode
In some cases, metals such as metals are used, but since the resistance is relatively low, a bus bar is not necessarily required on the counter electrode side in this case.

In addition, although various applications for the arrangement of the bus bar other than those in the embodiment can be considered, the arrangement in the embodiment in which it is provided all around the outer periphery is the best because the voltage drop across the entire surface of the cell can be reduced.

[Effect of idea]

With the conventional EC display cell shown in the comparative example, the response time required for coloring and decoloring was too long when the cell size was larger than 400 mm square, making it difficult to put it into practical use. Even though the EC display cell is large like this, it is equipped with a bus bar,
Moreover, by devising the structure, we were able to shorten the response time to a practical level and lower the driving voltage to a level comparable to that of a small cell.

Furthermore, if embossed copper foil is used, soldering is not necessary and sufficient adhesion can be obtained simply by pasting with adhesive tape or the like.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view showing the EC display cell of the present invention.
FIG. 2 is a plan view of a WO ₃ film and a bus bar formed on Nesa glass. 1, 1... Nesa glass, 2, 2... Transparent conductive film, 3... Display electrode, 4... Counter electrode, 5, 5...
...A conductive layer formed by baking a conductive paste, 6,
6...Copper foil, 7,7...Adhesive vinyl tape, 8
...Sealing material, 9...Electrolyte solution.

Claims (1)

[Scope of utility model registration request] The electrochromic layer is formed in an electrochromic display cell in which electrochromic layers that change color and fade are formed on a transparent conductive film with the outer periphery left in place, and each serves as a display electrode and a counter electrode. An electrochromic device characterized in that a bus bar having a structure in which a conductive paste is baked and an embossed copper foil is pasted on the conductive layer is provided on the outer peripheral portion of the conductive film that is not covered, and the bus bar portion is sealed. Display cell.