JPS61258888A - Electrochromic display element - Google Patents

Abstract

PURPOSE:To obtain the titled display element having excellent response speed, displaying speed and color variety, by attaching a display electrode to one of two substrates (at least one of which is transparent), attaching a counter electrode to the other substrate, and sealing a specific dye, a supporting electrolyte and a nonaqueous organic solvent in the space between the substrates. CONSTITUTION:The objective display element can be produced by attaching a display electrode to one of two substrates (at least one of which is transparent), attaching a counter electrode to the other substrate, and sealing a dye of formula I or formula II (the compound of formula III is a heterocyclic compound such as thiazoline, indolenine, alpha-naphthoindolenine, perinaphthoindolenine, benzothiazole, benzoselenazole, quinaldine, benzimidazole, etc.; X is Cl, Br, I, perchloric acid residue, carboxylic acid residue, or sulfonic acid residue; R1, R2 and R3 are lower alkyl), a supporting electrolyte and a nonaqueous organic solvent in the space between the substrates.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an electrochromic display element used for various displays such as watches, measuring instruments, and home appliances.

Compared to liquid crystal, which is one of the conventional light-receiving displays, electrochromic displays have no viewing angle dependence and have bright and clear colors. Electrochromic materials are classified into two types: inorganic materials and organic materials. Transition metal oxides, especially WO2, are well known as inorganic materials.

Organic substances include viologen and anthraquinone.

Pyrazoline and styryl-based pigments are known. In addition, the use of thin films of complexes or conductive polymers such as phthalocyanine and Prussian blue has recently been announced.

Problem WO3 to be solved by the invention is that a thin film is formed on a transparent electrode by a vapor deposition method or the like, and an electrolytic solution or a dielectric film is provided between counter electrodes to form an element. Practical problems with WO5 include, in addition to the display life, color unevenness between display segments and the fact that the coloring is only one blue color.

In addition, in connection with improving display life, there is a problem in that it is generally necessary to devise counter electrode materials in order to stabilize the counter electrode reaction, and also to incorporate a reflective plate or the like into the element.

On the other hand, compared to inorganic materials, organic dyes have the possibility of diversifying coloring types, but generally have a problem with display life.

Viologen-based dyes undergo a phenomenon in which they become insoluble or soluble in a solvent depending on whether they develop or fade, and this reversibility problem greatly affects display life.

In addition, the redox reaction of the dye causes the phenomenon of discoloration and discoloration, but since ions are involved in these reactions, the ions may have a negative effect on transparent electrodes, etc.
Another problem is that the power consumption is large. Similar problems exist with other organic dyes and complexes.

The characteristics that current electrochromic displays are inferior to liquid crystal displays are display life and response speed.

The present invention solves the above-mentioned conventional problems, and aims to improve the response speed and display life of an electrochromic display element.

Means for Solving the Problems The present invention achieves the above object, and its technical means is to provide a display electrode on one of two substrates, at least one of which is transparent, and a counter electrode on the other, and to In the space formed by the general formula (%), a heterocyclic compound such as gin, benzimidazole, etc. is added.

x is a halogen such as chlor, from, or iodine.

Indicates perchloric acid residue, carboxylic acid residue, and sulfonic acid residue. R+ + R2+ R5 represents the same or different lower alkyl groups. ) The present invention provides an electrochromic display element characterized by enclosing a dye represented by the following formula, a supporting electrolyte, and a non-aqueous organic solvent.

Effects of the present invention Since the present invention uses a displayable substance in which the dye shown in (1) or (D) is dissolved in a non-aqueous organic solvent together with a supporting electrolyte, an electrochemical redox reaction is reversibly and stably performed at a low voltage. In addition, it is possible to increase the response speed of color development and decolorization.

Example Embodiments of the present invention will be described below with reference to the drawings.

The basic structure of an electrochromic display element which is an embodiment of the present invention is shown in the figure. 1 is a glass substrate, 2 is a display pole,
3 is a counter electrode, 4 is a sealing material, 5 is a sealing material, and 6 is a displayable substance. The glass substrate 1 may be made of a material in which at least one side is transparent. As the electrode material for the display electrode 2 and the counter electrode 3, transparent electrodes such as In 203 and 5n02 are used. In terms of area, the display electrode 2 is smaller than the counter electrode 3. As the sealing material 4 and the pore sealing material 5, epoxy resin, low melting point glass, solder, etc. are used. The displayable substance 6 consists of a dye serving as an electrochromic material, a supporting electrolyte, and a solvent for dissolving these.

The electrochromic material, which is one of the necessary components of the displayable substance 6, is a dye having the general formula shown in the following formula.

Or (I[) -naphthoindolenine, perinaphthoindolenine.

benzothiazole, benzoselenazole, quinaldine,
Table 1. Heterocyclic compounds such as benzimidazole. x is a halogen such as chlor, from, or iodine.

Indicates perchloric acid residue, carboxylic acid residue, and sulfonic acid residue. R,, R2 and R5 represent the same or different lower alkyl groups. ) When the dye has the structure of formula 19, the dye is in a colored state, and most exhibit light absorption in the visible range. [In the case of the structure of formula R9, it is in a decolorized state and exhibits light absorption in the ultraviolet region, or even in the visible wavelength region, which is colored yellow on the shorter wavelength side.

As electrochromic materials, those exhibiting photochromism that develops color upon irradiation with sunlight or the like are inappropriate. The dye used here is difficult to exhibit photochromism. Electrochromism is electrochemical oxidation or reduction of N atoms in the pigment structure.
The color develops or fades. That is, the resonance structure changes due to oxidation or reduction of N atoms, and the light absorption state changes.

The dye is dissolved in a solvent and injected into the display element as shown in the figure, but the solvent must be selected from an electrochemically stable solvent. Additionally, a supporting electrolyte is added to the solution in order to obtain good coloring density and response speed.

Non-aqueous organic solvents are excellent as electrochemically stable solvents. For example, as an amide type, dimethylformamide and N-methylformamide are used.

N-methylacetamide, N-methylacetamide, N
- Nitriles such as methylpyrrolidone include acetonitrile, propionitrile, and benzonitrile; ketones include acetone;

Methyl ethyl ketone, methyl isobutyl ketone.

Examples of ethers such as acetylacetone include tetrahydrofuran, 1,4-dioxane, propylene carbonate, γ-butyrolactone, nitromethane, dichloroethane, and the like.

The supporting electrolyte may be anything as long as it is easily soluble in a non-aqueous organic solvent, and generally quaternary alkyl ammonium ions are used as cations, and other alkali metal ions such as Li+ and Na+.

K+, alkylphosphonium ions, etc. are used. Methyl, ethyl as alkyl groups.

Propyl and butyl groups are often used. Examples of anions include Cβ-, Br, I-, etc., NO5,0IO4- various sulfonate ions (for example, P-toluenesulfonate ion), BF4, PF
6- is used.

After injecting a solution in which a dye and a supporting electrolyte were dissolved in a solvent into a display element as shown in the figure, a voltage was applied between the display electrode and the counter electrode to cause color development and disappearance.

In the above-mentioned dye, in the case of the structure of formula R9, a coloring phenomenon occurs when a voltage is applied in the range of 0.5 to 1.51 so that the display electrode side becomes positive. This is due to the oxidation of the N atom, which creates two conjugated double bonds that exhibit visible light absorption.
This is because it is formed between two N atoms. When the voltage sign is reversed, the dye is reduced and decolored. [In the case of the structure of formula 19, it is in a colored state from the beginning due to the conjugated double bond between the two N atoms. In the case of this dye, there are cases where the color is erased by making the display electrode side positive with respect to the counter electrode, and cases where the color is erased by making the display electrode side negative with respect to the counter electrode. The reason for this is whether the two N atoms form a conjugated system or a non-conjugated system. Further, the potential for color development/decolorization differs depending on the ease of giving and receiving electrons due to the difference in electron density near the N atom.

The effects of a display element using such a dye are as follows.

■ Electrochemical redox reactions are reversibly and stably repeated by applying a voltage of 1.5V or less.

■ Colors can be diversified by changing the structure of pigments.

■ The response speed for color development and fading is fast among this type of element.

Next, specific examples of the present invention will be shown.

(Example 1) A dye having the following structural formula was used as an electrochromic material.

This dye was dissolved in acetonitrile at 0.02 M/l with tetrabutylammonium chloride as the supporting electrolyte) (T
BAP) was dissolved at a concentration of 0.2 M/6. After injecting the solution into a display element as shown in the figure, a voltage was applied between the display electrode and the counter electrode to examine the coloring and fading potential. -1 to display pole
, Ov is applied, the color changes from purple to colorless, and this is further changed to +○
, s When V is applied, the color changes from colorless to purple.

When voltages of -1, OV and +0.5 V were applied alternately to the display electrode, the color changed alternately between purple and colorless.

(Example 2) As an electrochromic material, the following structural formula was used as a supporting electrolyte: tetrabutylammonium (tetrafluoroborate) t-, and propylene carbonate was used as a bath medium.
A display element was produced by melting in the same manner as in Example 1. When no voltage is applied, it shows a yellow colored state, but when less than -1.1V is applied to the display electrode, it changes from yellow to colorless to -〇, 5V-o.
Press v to return from colorless to yellow.

(Example 3) An electrochromic material having the following structural formula was used.

This dye was dissolved in acetonitrile together with TBAP at the same concentration as in Example 1. When no voltage is applied,
Although it is colorless, it develops a red color when +1.0V or more is applied to the display electrode. When a voltage of -1.0 V or less is further applied to this, the color disappears from red to colorless. When +1.3v and -1.3v are applied in a 1-second cycle, a stable repeated reaction occurs about 1 million times.

(Example 4) An electrochromic material having the following structural formula was used.

This dye was added to acetonitrile with TBAP as a supporting electrolyte at Q, ○1M/l, and 0.3M/(
By dissolving it in a concentration of J, a display element as shown in the figure was made. When we looked at the color changes by changing the potential of the display electrode with respect to the counter electrode, we found that what was colored blue when no voltage was applied turned from blue to colorless at -1-0.5V or more, and then -〇, When 2V is applied, the color changes from colorless to blue, and when -1.0V or more is applied, the color changes to red.

It was found that when +0, T V and -0-2V were applied to the display electrode in a 1-second cycle, the change between colorless and blue was stably repeated about 1 million times.

The speed of change from blue to colorless when +0.7V was applied, and from colorless to blue when -0.2''/V was applied, was about 0.6 seconds.

Effects of the Invention In short, the present invention provides a display electrode on one of two substrates, at least one of which is transparent, and a counter electrode on the other. Remove heterocyclic compounds such as benzimidazole. xH Halogens such as dichlorobrome and iodine.

Indicates perchloric acid residue, carbo/acid residue, and sulfonic acid residue. Rlr R2+ R5 represents the same or different lower alkyl group. ) The present invention provides an electrochromic display element characterized by enclosing the dye represented by the following, a supporting electrolyte, and a non-aqueous organic solvent, and is excellent in response speed, display speed, and color diversity.

[Brief explanation of the drawing]

The figure is a sectional view showing the basic structure of an electrochromic display element that is an embodiment of the present invention. 1...Glass substrate, 2...Display electrode, 3
... Counter electrode, 4 ... Sealing material, 5 ...
...Sealing material, 6...Displayable substance.

Claims (1)

[Claims] A display electrode on one of two substrates, at least one of which is transparent;
A counter electrode is provided on the other side, and a general formula [I] ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ or [II] ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (In the formula ▲There are mathematical formulas, chemical formulas, tables, etc. ▼ represents a heterocyclic compound such as thiazoline, indolenine, α-naphthoindolenine, perinaphthoindolenine, benzothiazole, benzoselenazole, quinaldine, benzimidazole, etc. X is chlor, It represents a halogen such as bromine or iodine, a perchloric acid residue, a carboxylic acid residue, or a sulfonic acid residue. R_1, R_2, and R_3 represent the same or different lower alkyl groups.) The dye, supporting electrolyte, and An electrochromic display element characterized by enclosing a non-aqueous organic solvent.