JPS5870272A - Electrochromic display element - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrochromic display device (hereinafter referred to as FECD), and particularly to a type in which two types of electrochromic substances (hereinafter referred to as EC substances) are used and each color contributes to a visual effect. This is related to ECD.

The phenomenon in which the light absorption characteristics of a substance change due to an electrochemical reaction is called electrochromism, and among the substances that exhibit this phenomenon, that is, EC substances, those with high reaction reversibility and good visual effects are used in display devices. j; The river is ECD. There are many known EC materials used in ECDs (for example, Electronics II ($15
5, August issue P, 832-835). This EC material can be classified in various ways depending on the viewpoint. For example, focusing on chemical composition, substances can be broadly classified into inorganic substances and organic substances. E
Focusing on the phase change accompanying the C reaction, it can be classified as follows.

Liquid C Solid ° Precipitated Solid - Solid types use a solid as a source of ions necessary for the EC reaction, but are classified into all-solid type and semi-solid type depending on whether a liquid (ie, electrolyte) is used. As a solid ion supply source, there are cases where an essentially solid electrolyte in a narrow sense is used and cases where a dielectric thin film is used. In the latter case, H2 or OH- produced by decomposition of water adsorbed on the dielectric film interferes with the EC reaction. In this specification, for convenience, both will be collectively referred to as a solid electrolyte. In the deposition type, the EC substance dissolved in the electrolyte becomes an insoluble film through an electrochemical reaction and is deposited on the electrode surface. In the simple liquid type, the EC substance remains liquid even during the coloring reaction, but it has the disadvantage that bleeding occurs because the colored species diffuses. The following self-erasing type and diffusion type were devised to avoid this drawback. In the self-erasing type, an erasing agent is added to the electrolytic solution to chemically erase the colored species that have diffused. In the diffusion type, the electrolyte is prepared so that it is colored when it is not electrically energized, and when it is electrically energized, a decoloring reaction occurs so that the color of the background material is visible. be.

Also, if you pay attention to the change in color, you can see that it is monochromatic (colorless and transparent - colored).
, can be classified as bicolor or multicolor (hue changes). Furthermore, monochromatic materials are classified into ``reduction coloring type'' and oxidation coloring type.

To give a specific example, WO3 is an inorganic substance, all solid type or semi-solid type, m-color, and reduction coloring type, and IrO2 is an inorganic substance, all solid type or semisolid type, monochromatic, and oxidation coloring type. Viologen is an organic substance, precipitated type, monochromatic, and reductive coloring type, and Shiftalodianine lutetium is an organic substance, semisolid type, and multicolor.

According to the display format, there are two types: positive display, negative display, and transmissive type and reflective type. The reflective type is further divided into those using a metal reflective electrode and those using a transparent electrode with a background material provided inside the element.

ECU is a type of electrolytic cell. If an oxidation reaction occurs at one electrode when current is applied in a certain direction, an equivalent reduction reaction occurs at the other electrode, and when electricity is applied in the opposite direction, an opposite reaction occurs at each electrode. Traditional typical EC
In D, only coloring or discoloration caused by a reaction at one electrode (display electrode) was used for display, and the other electrode (i.e., counter electrode) was configured to be visually hidden behind the background material.

The reason why the counter electrode must be hidden by the background material is as follows. If the same EC substance that causes a reaction at the display electrode is used as the substance (active material) involved in the electrochemical reaction at the counter electrode, when either the display electrode or the counter electrode is colored, the other one is turned off. They are colored, and if one is decolored, the other is colored. Therefore, if you look at the two together, they will appear colored in either state, making it difficult to observe changes in coloring and decoloring due to energization. Furthermore, even if a material with low reflectance such as a carbon sintered body is used as the counter electrode, changes in the display electrode cannot be observed as it is.

On the other hand, the type of ECD to which the present invention is applied does not distinguish between a display electrode and a counter electrode, and one electrode is provided with an oxidation coloring type EC material and the other electrode is provided with a reduction coloring type C material, so that both It has a structure with a solid electrolyte layer interposed between them. The EC materials on both electrodes are colored at the same time when electricity is applied in one direction, but since there is no background material between them, the superimposed colors of each color are observed, so the contrast ratio when the same amount of charge is applied is Much improved compared to the conventional one.

If they go in the opposite direction, both will be erased at the same time. When conventional cell structures are used in these types of ECUs, the following drawbacks appear. For example, as shown in FIG. 1, a first electrode 2 made of a transparent conductive film and a first EC material layer 3 are provided on a glass substrate 1, and then a second EC material layer 5 is formed via a solid electrolyte layer 4. In an ECD in which a plurality of first electrodes 2 and a second electrode 6 are superimposed, if a common electrolyte layer 4 and a common second electrode 6 are arranged for a plurality of first electrodes 2, Color bleeding occurs in the display pattern. This phenomenon is caused by the fact that the lines of electric force are expanded laterally during writing as shown by the arrows in the figure, and the same goes for the commercial path.As a result, the colored pattern area of the second electrode 6 is larger than that of the first electrode 2. This is caused by the colored species being diffused from the colored area of the second electrode 6 to the non-colored area during the memory period, and the entire surface of the second electrode 6 is colored due to the expansion of the colored area. is also assumed. Therefore, in segment display, the light transmittance of non-selected segments is reduced, resulting in a lower contrast ratio.

This bleeding phenomenon occurs in the second EC material layer 5 as shown in FIG.
The same problem occurs even when the first EC material layer 3 is divided and formed in the same pattern as the first EC material layer 3. The reason for this is that the electric potential difference caused by the difference in color density becomes a driving force and a current flows spontaneously within the cell in a direction that equalizes the difference in color density, resulting in the uncolored area being colored. . Note that the arrows in the figure explain the bleeding phenomenon when the colored layer 1 is of the cation-emitting type, and when the charge of the ion species is opposite, the direction of the arrow indicating the movement of the ions is also opposite. becomes.

In order to prevent the bleeding phenomenon, a structure as shown in FIG. 3 is adopted in which the lead portion of the second electrode 6 is divided together with the second EC material layer 5, or a structure in which the electrolyte layer 4 is divided by an insulating separation layer 7 is adopted. It is assumed that a structure as shown in FIG. 4 is effective. In the structure shown in FIG. 3, when driving the ECD, it is necessary to select the first electrode 2 and the second electrode 6 to be paired, respectively, which leads to an increase in the number of lead terminals and driving switching elements, and the circuit configuration. becomes complicated.

The present invention is based on the ECD having the structure shown in FIG. 4, in which the solid electrolyte and the second EC material layer are formed in the same pattern as the first EC material layer, and a dense insulating film is formed in other areas. f! is provided to separate unit elements of the display pattern and prevent the display pattern from bleeding. ] new useful E
The purpose is to provide CDs.

Hereinafter, the present invention will be described in detail in accordance with embodiments in the order of manufacturing steps with reference to the drawings.

An insulating film is provided on the entire surface of the substrate on which the first electrode has been provided in advance, and then a resist layer is provided on the portion where the insulating film is to be left, and the insulating film is etched on the portion where the resist layer is not provided. Remove by.

In a normal patterning method, the resist is peeled off at this point, but in the following examples, this resist is used as a lift-off resist for patterning a colored layer to be provided next.

That is, a colored layer is laminated on the L while leaving the resist, and then the resist is peeled off and the colored layer in that portion is removed.

According to this method, the edges of the colored layer and the insulating film coincide with each other, and neither overlap nor gap occurs. Furthermore, the first
The three layers of the EC material layer, the solid electrolyte layer, and the second EC material layer were treated as a single colored layer, but since they are layered in sequence and patterned at the same time with the same resist, their edges are aligned. No discrepancies have occurred.

Although the case where the insulating film is provided first and then the colored layer is provided has been described here, it is natural that patterning can be achieved in exactly the same way even if the order in which the colored layer and the insulating film are provided is reversed.

The embodiments shown in the drawings will be described below.

5th Doujin to (G) are explanatory diagrams of manufacturing process of ECD showing one embodiment of the present invention.

A conductive film is provided on one side of the substrate 1 during the process, and patterned as necessary to form the first electrode 2. Glass and ceramic are used for the substrate l, but polymeric materials can also be used in some cases. The conductive film is an ITO film mainly made of In2O3,
A NESA film mainly composed of 5n02 is used.

For patterning the ITO film, it is convenient to use a wet etching method or, in the case of a NESA film, a lift-off method. This process is shown in FIG. 5 (8).

Step Q3): Next, an insulating film 8 is provided on the entire surface of this L.

The insulating film 8 is 5i02. Si3N4 is used.

Methods for providing these include a CVD method, a sputtering method, an ion blasting method, and a thermal decomposition method. The mouth process is shown in FIG. 5(B).

(2) - Culm (C) A resist 9 is provided on the secondary lead portion and other areas where the insulating film 8 is to be left by a method such as screen printing. As the resist 9, an inorganic resist is preferable. This is because organic resists are mainly composed of resin and have poor heat resistance, and when heated, they turn black and become difficult to peel off. Another disadvantage is that when the EC material described later is provided, gas is released and the characteristics are adversely affected. On the other hand, inorganic resists are mainly composed of a portion of filler (inorganic powder, carbon, metal powder), which is made into a paste by adding a small amount of resin and a solvent, and is baked in advance so that only the filler portion is removed. The problem that occurs with residual organic resists does not occur. Moreover, it can be easily peeled off with water, dilute acid, etc. In this example, resists containing BaCO3 and CaC'03 as main components, such as MSK-428 (manufactured by MINETCH) and Bunny Height S (manufactured by Nippon Graphite Industries), gave particularly good results.

This process is shown in FIG. 5(C).

Step (D): Next, the part not covered by the resist 9 (E
The insulating film 8 (the portion where the C substance is provided and the terminal portion) is removed by dry etching to expose the conductive film 2. FIG. 5(D) shows a zero-fill process in which only 5i02 was etched and the conductive film was not damaged when CF4 was used as the etching gas.

Step (E): Next, the terminal portion is masked and the other portions are covered with the first EC material layer 3. Solid electrolyte layer 4. Second EC material layers 5 are sequentially laminated. First EC material layer 3, second EC
Either one of the material layers 5 is made of W2B or Mo+03 as a reduction color-forming E'C material, and the other is made of NiO or ■r(')2 as an oxidation color-forming EC material, by a method such as vacuum evaporation, sputtering, or ion blating. Layered. Further, as the solid electrolyte layer 4, a pure solid electrolyte such as Li3N or 5i02. CaF2. A porous vapor deposited film such as MgF2 is used. In a porous deposited film, adsorbed water becomes a source of ions necessary for the EC reaction.

This process is shown in Figure 5).

Step (F): Next, remove the resist 9 with dilute hydrochloric acid and the first
EC material layer 3, solid electrolyte layer 4, second EC material layer 5
is molded with the edges aligned to the display pattern shape of the new house. This process is shown in FIG. 5(F).

In step (G), finally, a conductive film that will become the second electrode 6 is layered so as to be in contact with the second EC material layer 5, thereby completing the ECD. After this, a resin coating or a protective plate may be attached for protection as necessary. Note that since the colored layer is patterned and separated into segments, there is no need to divide the second electrode 6. Substrate l, first electrode 2
If both of the second electrodes 6 are substantially transparent, the ECD becomes a transmission type ECD, and the display pattern can be observed from either of the two surfaces. Further, if a white or light-colored opaque substrate obtained by mixing a material into glass or ceramic is used as the substrate 1, or a metal film is used on either of the poles 2 and 6, a reflective type can be obtained.

When the display pattern is not divided into segments, a metal plate can serve as both the substrate 1 and the first electrode 2. In the reflective type, the display and background are in close contact with each other in any case, and there is no parallax as seen in liquid crystal display elements, so good visual effects can be obtained.

In the following explanation, the insulating film 8 was provided first and patterned by dry etching, but in contrast to this, the first E
A C material layer 3, a solid electrolyte layer 4-1, and a second EC material layer 5 are sequentially laminated, and after patterning them by dry etching, an insulating film 8 is provided, and unnecessary portions of this insulating film 8 are removed. It may be removed by law.

As explained in detail above, the ECD of the present invention has a simple structure, can be manufactured efficiently, and is extremely effective in eliminating the bleeding phenomenon in the colored area of the display pattern without increasing the number of electrode terminals. It has high practical value.

[Brief explanation of drawings]

1 to 5 are explanatory diagrams of the manufacturing process of an ECD showing one embodiment of the present invention. 0 1... Substrate, 2... First electrode, 3... First
4... Electrolyte layer, 5... Second EC material layer, 6... Second electrode, 8... Insulating film. Agent Patent Attorney Aihiko Fukushi Procedural Amendment Date 1986-Mon/2 1.1 Indication of Patent Application Sho, 5 O-, 2/θ622/2, Invention Name: Electrochromic display element 3, consideration for arresting 11/Relationship with 11 cases Patent address: 22!22, Nagaike-cho, Abeno-ku, Osaka-shi, Osaka 8545 Name: 1;j. (5o4) Representative Isa of V-Yap Corporation
Haku Asahi 4, Agent Address 6, 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka 8545 Subject of amendment (1) Column for detailed explanation of the invention of Akiba-sen (1) Specification of the invention In the explanation section, /θ
On the page/line 1, correct the text "Formula 1 etching method, NESA film..." as [Formula 1, notching method, NESA film...]. (2) Same, /, page 2/line 2 [-...view...
・"It says 1...pigment..." and I couldn't help but type it. (3) In the brief explanation section of specification a, /
In the last line, it says, "Figs. 1 to 5 are the present invention...". It is replaced by "Figs. 7 and 2 are configuration diagrams showing the cell structure of a conventional ECU. Figure 7 is a configuration diagram assuming that the cell structure of a conventional ECD has been improved. Figure 5 shows the present invention.

Claims (1)

[Claims] 1 By pattern-forming a colored layer and an insulating layer in which an oxidation color-forming EC layer and a J'q original color-forming EC layer are laminated via a solid electrolyte layer, the colored boundaries of adjacent parts of the phase Ti'' are made to match the display pattern. . An electronics/display element, characterized in that the colored layer is divided into elements of a display pattern by the insulating layer.