JPS592020A - Electrochromic display element - Google Patents

Abstract

PURPOSE:To obtain a display element which is driven at low voltage, responds at high speed and has superior durability by forming an electrochromic (EC) material layer with a transition metallic oxide and an ionic conductive material layer contacting with the EC material layer with an org. polymer and an inorg. ionic conductive material. CONSTITUTION:A transparent electrode 2 is formed on a transparent glass substrate 1, and an EC material layer 3 of MoO3 or WO3 is formed on the electrode 2 by vacuum deposition or other method. A uniform mixture of a soln. of an org. polymer such as polymethyl methacrylate with an inorg. ionic conductive material such as LiClO4, LiF or NaF is applied to the layer 3 and dried to form an ionic conductive material layer 4. A transparent electrode 5 is formed on the layer 4 by sputtering, and the void is sealed with epoxy resin to obtain an entirely solid EC display element. By adding a white pigment such as TiO2 or Al2O3 to the layer 4, the background may be prevented from being seen through the layer 4 to improve the decorative effect. The generation of H2 by a reaction between the electrodes is prevented in the element, and the element causes no liq. leak and has superior durability.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an electrochromic display element, and more specifically, an electrochromic display element that does not cause short circuits between electrodes and has good adhesion with an electrochromic layer. The present invention relates to an electrochromic display element which has a fast response speed for color development and fading and whose display function does not deteriorate even when used for a long period of time.

[Technical background of the invention and its problems]

Conventionally, in electrochromic display elements that use transition metal oxides in the electrochromic material layer, the liquid ion conductive material formed in contact with the electrochromic material layer has been used to speed up the coloring/decoloring response speed and provide good punnlast. For this purpose, for example, an electrolytic solution containing mainly acids having high cation mobility, such as sulfuric acid, is used. However, when these are used for a long period of time, they have a problem in that the electrolyte tends to leak from the electrochromic display element. Therefore, when manufacturing an electrochromic display element, it is necessary to seal the electrolyte in a liquid-tight manner, resulting in the problem that the manufacturing process is complicated and work efficiency is reduced.

On the other hand, examples of solid ion conductive materials include silicon dioxide (SlO), magnesium heptatide (MtFt), etc.
Inorganic ion conductive materials such as calcium fluoride (CaF), or organic ion conductive materials such as perfluorosulfonic acid resin, styrene sulfonic acid resin, and acrylic resin are used. However, the former has a problem in that the transparent electrode and the counter electrode are easily short-circuited through pinholes existing in the ion-conductive material layer and the electrochromic material layer. In addition, the productivity is poor during manufacture, making it unsuitable for practical use. On the other hand, when an organic ion conductive material such as a polymeric resin is used, there is a problem that if the adhesion of the interface with the electrochromic material layer is poor, ion movement at the interface will not proceed smoothly. There is. Furthermore, since the cation movement speed in the organic ion conductive material layer is low, the response speed for developing and decoloring is slow and takes about 2 seconds.

Furthermore, regardless of whether the ionic conductive material is liquid or solid, conventional electrochromic display elements generally tend to generate hydrogen through side reactions, so stannic oxide, which is used as a transparent electrode, is A metal oxide such as (SnO,) or indium oxide (IntOs) is reduced by hydrogen to become metal Sm, metal In, or the like. Therefore, when used for a long period of time, the display area of the electrochromic display element becomes unevenly brown or black due to metal 8n or metal In produced by reduction, resulting in a problem that the display function deteriorates. are doing.

[Purpose of the invention]

The purpose of the present invention is to solve the above-mentioned problems, eliminate short circuits between electrodes, have good adhesion with the electrolyte material layer, and improve the response speed of color development and fading. It is an object of the present invention to provide an electrochromic display element that is fast and does not generate hydrogen during long-term use and whose display function does not deteriorate.

[Summary of the invention]

The electrochromic display element of the present invention is an electrochromic display element comprising an electrochromic material layer between electrodes and an ion conductive material layer in contact with the electrochromic material layer, wherein the electrochromic material layer is formed from a transition metal oxide. , and the ion conductive material layer is made of an organic polymer resin and an inorganic ion conductive material.

Further, in the electrochromic display element of the present invention, the ion conductive material layer may further contain a pigment.

In the following, the invention will be explained in more detail.

A schematic configuration diagram of an electrochromic display element according to the present invention is shown in the drawings. In the drawing, a transparent electrode (2) is placed on the substrate (υ).
, an electrochromic material layer (3), an ion conductive material layer (4), and a counter electrode (5) are shown.

The material constituting the electrochromic material layer according to the present invention is not particularly limited as long as it is a transition metal oxide; for example, tungsten oxide (WOI), molybdenum oxide (
M・0. ), titanium oxide (TIO, ), and the like.

Materials L1 constituting the ion conductive material layer according to the present invention are an organic polymer resin and an inorganic ion conductive material. There are no particular restrictions on the organic polymer resin as long as it is transparent during film formation, such as polystyrene, polyvinyl chloride, vinyl chloride-vinyl acetate co-li, polyvinyl acetate, polyvinyl acecool, and phenol. Resins, epoxy resins, alkyd resins, acrylic resins, polyacrylonitrile, butadiene-based synthetic rubbers, polyolefins, etc.;
The above are used.

As an inorganic ion conductive material, Li2, which is involved in color development and fading
Or N? There is no particular restriction as long as it contains lithium fluoride (LIF), lithium fluoride (LIF),
II), lithium hydroxide (Lion), lithium perchlorate (t, tczo, ), sodium fluoride (NaF)
, sodium iodide (NaI), sodium hydroxide (N
aOH) and sodium perchlorate (Na(,to,), etc., and one or more selected from the group consisting of these are used.The blending amount curve of this inorganic ion conductive material , 0.01 to 10 for organic polymer resin
00 weight, more preferably 20
~100% by weight. If the blending amount of the inorganic ion conductive material is less than 0.01% by weight, the contrast during coloring will decrease and the display function will be poor.
If it exceeds this value, the film forming properties of the composite material will deteriorate and it will become difficult to obtain an ion conductive material layer with a uniform composition.

The ion conductive material layer according to the present invention may further contain a pigment for the purpose of improving the display function and imparting a cosmetic effect. Pigments used in the present invention include, for example, titanium dioxide (TlOt), aluminum oxide (Az, os), ignium oxide (MfO), zirconium oxide (ZrOl), and yttrium oxide (y*).
Os), tantalum pentoxide (Ta, 0.) and silicon dioxide (white pigments such as 810, nickel titanium yellow,
Coloring pigments such as cadmium yellow, chrome yellow, cadmium red, molybdenum orange, and red iron oxide may be mentioned, and one or more selected from the group consisting of these pigments may be used. Among these, it is particularly preferable to use white pigments from the viewpoint of cosmetic effect. The blending amount of the pigment described above is preferably 3 to 50% by weight, more preferably 10 to 30% by weight based on the organic polymer resin.

If the amount of pigment added is less than 5% by weight, the background color will be pale and transparent, resulting in insufficient cosmetic effect;
If it exceeds 50% by weight, the film formability and ionic conductivity of the ion conductive material layer will decrease.

Other materials used in the present invention may be those commonly used in electrochromic display elements.

For example, a transparent material such as glass or polyester is used for the substrate. For example, the transparent electrode and the counter electrode include:
In! 0. , BnO,, ^t11II are used.

The electrochromic display element of the present invention constructed using the above-mentioned materials can be manufactured, for example, as follows. That is, first, a transparent electrode is formed on a substrate using a conventional method such as sputtering. Next, an electrochromic material layer is formed on the transparent electrode using a method such as vapor deposition.

To form the ion conductive material layer, first, a predetermined amount of an organic polymer resin and an inorganic ion conductive material are blended, dispersed and mixed, or a pigment is further added and blended, dispersed and mixed. The viscosity of this mixture is adjusted by diluting it with an appropriate solvent as necessary, or by using an organic polymer resin diluted in advance with a solvent. Alternatively, it is possible to apply onto the electrochromic material layer using a spray coating method. When a solvent is used, for example, 50 to 15
It is preferable to perform the heat treatment in a temperature range of 0°C. still,
Examples of the solvent used to adjust the viscosity of the above-mentioned ion conductive material include methyl ethyl ketone, methyl isobutyl ketone, toluene, xylene, cresol, ethyl cellosolve acetate, ptylsetasol acetate, propylene carbonate, acetonitrile, dimethyl acetamide, Examples include non-aqueous solvents such as N-methylpyrrolidone and dimethylformamide, and one or more solvents selected from the group consisting of these are used. Further, it is preferable that the concentration of the ion conductive material liquid after diluting with a solvent is appropriately adjusted by a coating method. Next, a counter electrode is formed on the ion conductive material layer using a method such as sputtering in the same manner as in the formation of the first transparent electrode, thereby obtaining the electrochromic display element of the present invention.

〔Effect of the invention〕

In the electrochromic display element of the present invention, since the ionically conductive material layer is formed by a coating method, no pinholes or the like occur, and therefore no short circuit between the electrodes occurs. Further, since the adhesion between the electrochromic material layer and the ion conductive material layer is good, the response of coloring and fading is quick.

Furthermore, since the electrochromic display element of the present invention develops and erases color using inorganic ions such as Ll+ or teeth 4 in the ion-conductive material layer, no hydrogen is generated even during long-term use. , it has the advantage that there is almost no deterioration in display function.

The electrochromic display element of the present invention having the above-mentioned advantages can be manufactured with a homogeneous thin film-like ion conductive material layer through a simple process.

[Embodiments of the invention]

Examples 1 to 10 A transparent conductive film made of In*Os was formed on a glass plate using a sputtering method, and the conductive film was patterned with electrodes to enable a desired display, and then oxidized on the conductive film. Tungsten was deposited to a thickness of 0.3 pm.

On the other hand, the 10 types of compositions for forming an ion conductive material layer shown in Table 1 were labeled Ill#. That is, a predetermined amount of an inorganic ion conductive material was added to a solution of each organic polymer resin in a suitable solvent, and the mixture was thoroughly dispersed using a ball mill and a three-roll mill.

The composition was applied onto the substrate having the above-mentioned pieces and films using the dipping method, spinning method, spray method, and low-two method shown in Table 1. Then,
This substrate was left on an iron plate heated to 100° C. for about 30 minutes to dry, thereby forming a thin film of a homogeneous ion-conductive material layer.

On each ion conductive material layer, rnto was sputtered to a thickness of 0.2 μm to form a counter electrode.

[xO
Various types of electrochromic display elements were obtained.

Comparative Examples 1 to 2 As a comparative example, two types of electrocoloring were performed in the same manner as in the examples except that the ion conductive film NAFION (trade name) manufactured by DuPont shown in Table 1 was used as the ion conductive material layer. A display element was obtained.

Contrast ratio (H@-N
The voltage and response time required for the ratio of absorbance during color development to absorbance during decolorization (at @V-za (633 mm)) to be 3 were investigated. The results are also shown in Table 1.

Table 1 *Additional amount indicates the addition amount (weight X) relative to the organic polymer resin.

As is clear from the table, the electrochromic display elements of the comparative examples have thick electrolyte layers and therefore have slow response speeds at high driving voltages, whereas the devices of the present invention can be driven at low voltages. It has been confirmed that the response speed is quick.

Furthermore, in the electrochromic display element of the present invention, a clear dark blue pattern is displayed when a voltage is applied so that the display electrode side is negative, and a clear pattern of dark blue is displayed when a voltage of the opposite polarity is applied. ], the display pattern is quickly erased.

Furthermore, the electrochromic display element of the present invention is free from side reactions of the electrodes.
It was confirmed that there was no generation of hydrogen, etc., and that it was electrochemically stable.

Examples 11 to 20 Glass plates similar to those used in Examples 1 to 1O were prepared, and a transparent electrode and an electrochromic material layer made of tungsten oxide were formed in the same manner.

On the other hand, 10 types of compositions for forming six layers of ion conductive materials shown in Table 2 were prepared. That is, a solution K of each organic polymer resin in a suitable solvent, a predetermined amount of an inorganic ion conductive material and a pigment were added, and the mixture was thoroughly dispersed using a triple roll.

Next, in the same manner as in Example 1-10, an ion conductive material layer was formed using each coating method shown in Table 2.

Furthermore, Nl was vapor-deposited as a counter electrode on each of the ion conductive material layers to a thickness of 0.2 mm, and then sealed with epoxy resin in the same manner as in the previous example. An electrochromic display element was obtained.

For each of the electrochromic display elements obtained in Examples 11 to 20 above, the voltage and response time required for the contrast 5f ratio to reach 3 were investigated. The results are also shown in Table 2.

Table 2** All amounts added are based on the amount (by weight) of the organic polymer resin.

As is clear from the table, it was confirmed that all of the electrochromic display elements of the present invention can be driven at low voltage and have quick response speed.

Further, in the electrochromic display element of the present invention, by applying a voltage so that the display electrode side is negative, clear dark blue bars and turns are displayed on a white background, and when a voltage of opposite polarity is applied. Furthermore, the electrochromic display element of the present invention does not generate hydrogen or the like because no side reactions occur between the electrodes, and is electrochemically stable. It was confirmed that the compound was stable.

[Brief explanation of the drawing]

The drawing is a cross-sectional view of a configuration example of an electrochromic display element according to the present invention. (1)...Substrate, (2)...Transparent electrode, (3)...
- Electrochromic material layer, (4)... ion conductive material layer, (5)... counter electrode.

Claims (2)

[Claims] (1) An electrochromic material layer between the electrodes,
An electrochromic display element comprising an ion conductive material layer in contact with the electrochromic material layer, wherein the electrochromic material layer is made of a transition metal oxide, and the ion conductive material layer is made of an organic polymer resin and an inorganic ion conductive material. An electrochromic display element characterized by: (2) The electrochromic display element according to claim 1, wherein the ion conductive material layer further contains a pigment.