JPH03241322A - Electrochromic material and display element - Google Patents

Abstract

PURPOSE:To obtain an electrochromic material performing a stable oxidation- reduction cycle, having such satisfactory workability as to enable the formation of a uniform thin film and producing a colorless transparent state when a developed color is vanished by using a specified copolymer. CONSTITUTION:A copolymer represented by formula I is used as a component to obtain an electrochromic material performing a stable oxidation-reduction cycle, having such satisfactory workability as to enable the formation of a uniform thin film and producing a colorless transparent state when a developed color is vanished. In the formula I, R<1> is H or 1-20C residue of hydrocarbon, R<2> is H, 1-20C residue of hydrocarbon, furyl, pyridyl, nitrophenyl, chlorophenyl or methoxyphenyl, l is an integer of >=2, m is an integer of >=1 and n is an integer of >=2.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is an electrochemically active method, that is, it is possible to dope and dedope electrolyte ions by an electrochemical method, and the accompanying reversible generation and dedoping of electrolyte ions is possible. The present invention relates to an electrochromic material and a display element characterized by using a copolymer having color erasing properties.

(Prior art) As electrochromic (EC) materials used in display elements that utilize electrochromic phenomena, WO is a well-known inorganic material, and conductive polymers such as polyaniline, polypyrrole, and polythiophene are organic materials. , viologen, pyrazoline, anthraquinone, various pigments, and other compounds are well known.

However, WO has practical problems in that it has a short display life, color unevenness between display segments, and is colored in a single blue color. In addition, in order to stabilize the counter electrode reaction, special efforts must be made to the material of the counter electrode, and there is also the problem that a reflecting plate and the like must be incorporated into the element.

In addition, viologen dyes develop color when reduced, and return to a decolored state when oxidized, but there is a problem with this reversibility, so the display life is short. Furthermore, since ions are involved in these redox reactions, there are problems in that these ions may have an adverse effect on the transparent electrode and consume a large amount of current.

(Problems to be Solved by the Invention) In order to solve the above problems, attempts have been made to use various conductive polymers as electrochromic materials.

However, most conductive polymers are insoluble and infusible and have poor processability, which is an obstacle to the practical application of EC devices, which require uniform thin film control on the submicron order to eliminate color unevenness. There is. Therefore, when applying a conductive polymer to an EC device, a method is generally adopted in which a monomer dissolved in an electrolytic solution is directly polymerized and deposited on a current collecting electrode by an electrolytic polymerization method. However, even with the electrolytic polymerization method, it is difficult to synthesize a uniform thin film over a large area, and general organic polymers have good processability and can be made into large areas and uniform thin films. It has lost its most important feature. In addition, many conductive polymers exhibit good EC properties, but even when decolorized (reduced), they are colored in some tone and do not become colorless and transparent. It cannot be used as a light control element, although it can be used to adjust the amount of light.

Therefore, there has been a desire for an EC material that can be subjected to stable redox cycles, has good workability that allows it to be formed into a uniformly thin film, and is colorless and transparent in a decolorized state.

As a result of intensive research to improve these shortcomings, the present inventors have found that the shortcomings of the prior art can be solved by using a copolymer represented by the following general formula (1) in an EC material. This is the heading that led to the present invention.

(Means for Solving the Problems) That is, the present invention has the general formula (I) (wherein, R'' is H or a hydrocarbon residue having 1 to 20 carbon atoms, and R2 is H1 a hydrocarbon residue having 1 to 20 carbon atoms. residue, furyl group, pyridyl group, nitrophenyl group, chlorophenyl group or methoxyphenyl group, l is an integer of 2 or more, m
is an integer of 1 or more, and n is an integer of 2 or more.

The present invention also relates to an electrochromic element comprising an electrode, an electrolyte, and a counter electrode formed by coating the above-mentioned material on an S electric body.

The copolymer represented by the general formula (I) used in the present invention is a compound represented by the general formula (II) and the general formula (I[
) or a polymer thereof.

R2CHO(][) In the compound represented by the general formula (old), °R1 represents hydrogen or a hydrocarbon residue having usually 1 to 20 carbon atoms, preferably 1 to 8 carbon atoms, and examples of the hydrocarbon residue include, for example, methyl group, ethyl group, n-propyl group, !-propyl group, n-
Examples include alkyl groups or allyl groups such as butyl group, l-butyl group, n-hexyl group, various aryl groups such as phenyl group, tolyl group, ethylphenyl group, aralkyl group and derivatives thereof. e is 2 or more, usually 2
-50, preferably 2-10, more preferably 2-5. m is 1 or more, usually 1 to 50. Preferably 1
~30. More preferably, it is 1-10. Although both terminals of the formula are not particularly specified, they are usually nuclear substituted hydrogen.

Specifically, the compound represented by the general formula (]II is +
, tN, N'diphenyl-p-phenylenediamine type compounds, N-phenylN'-(4-phenylamino)phenyl-p-phenylenediamine type compounds, and the like.

Furthermore, among the compounds represented by the general formula (II), those in which m is 2 or more are usually represented by the general formula (II) where m=
The compound in case 1 is produced by using a method such as an oxidative coupling reaction using an oxidizing agent such as a manganese compound or a ferric salt, or electrolytic oxidative polymerization. For example, if the compound represented by the general formula (old) is N.

In the case of N'-Schiff2nyl-p-) 22-diamine-based compounds, N.

N'-diphenyl-p-phenylenediamine can be produced by an oxidative coupling reaction using ferric chloride as a catalyst in a solvent such as ethanol, acetone, acetonitrile, ether, or benzene.

The reaction concentration at this time is usually -50°C to 100°C, preferably -20°C to the boiling point of the solvent used, and the reaction time is usually 10 minutes to 100 hours, preferably (1 hour to 50 degrees Celsius).
Be able to perform a reaction in time.

Note that representative examples of these N,N'-diphenyl-p-)22 diamines include, for example, N,N'-diphenyl-p-)
'-dimethyl-N,N'-diphenyl-p-phenylenediamine, N,N'-diethyl-N,N'-diphenyl-p-phenylenediamine, N.

Examples include N'-dipropyl-N, N'-Schiff, and nyl-p-phenylenediamine.

In addition, compounds represented by general formula (I[) other than N,N'-diphenyl-p-phenylenediamine compounds can also be produced by conventional methods, such as aromatic amines in the presence of a transition metal catalyst. A method of reacting an aromatic hydroxy compound with an aromatic hydroxy compound in an organic solvent, a method of using a phthalate ester as a raw material, etc.
of Po1y+++er 5science Par
t C22, p, 451 (1968), etc.

In the aldehyde represented by the general formula (Ilrl), R2 is hydrogen or has a carbon number of usually 1 to 20, preferably 1.
~8 hydrocarbon residues, or compounds of furyl, pyridyl, nitrophenyl, chlorophenyl, methoxyphenyl groups are used, and examples of the hydrocarbon residues include methyl, ethyl, n-propyl, Alkyl groups or allyl groups such as l-propyl group, n-butyl group, 1-butyl group, n-hexyl group, phenyl group, tolyl group,
Various aryl groups such as ethylphenyl groups, aralkyl groups, and derivatives thereof can be used. Representative examples of these aldehydes include formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, benzaldehyde, acrylaldehyde, cinnamaldehyde, anisaldehyde, nicotinaldehyde, nitrobenzaldehyde, chlorobenzaldehyde, and furfural. .

Furthermore, the term "aldehyde polymer" refers to a polymer obtained by self-condensing an aldehyde represented by the general formula (I) in a concentrated solution or by condensing it in the presence of an acid catalyst, and the polymer is obtained by the present invention. represents a compound that is easily hydrolyzed to produce an aldehyde monomer under the reaction conditions used to synthesize the copolymer. Typical examples include paraformaldehyde, which is a polymer of formaldehyde, and paraaldehyde, which is a trimer of acetaldehyde.

The polycondensation of the compound represented by the general formula (old formula) and the aldehyde or its polymer represented by the general formula (I) is carried out using an acid or alkali catalyst in an organic solvent in which both are soluble, usually at a temperature of 0 to 200°C. Examples of the acid catalyst include inorganic acids such as sulfuric acid, hydrochloric acid, phosphoric acid, perchloric acid, diline pentoxide, formic acid, acetic acid, propionic acid, methanesulfonic acid, and p-)luenesulfonic acid. Can you name some organic acids such as These acid catalysts may be used alone or in combination of two or more. Examples of the organic solvent include ethers such as ethyl ether, tetrahydrofuran, and dioxane, halogenated hydrocarbons such as chloroform, dichloromethane, and chlorobenzene, nitro compounds such as nitrobenzene, acetonitrile, propylene carbonate, dimethylformamide, N- Examples include methylpyrrolidone. The reaction time can be selected as appropriate, usually from 1 minute to 500 hours, preferably from 5 minutes to 200 hours.

In the thus obtained copolymer represented by the general formula (I), n is 2 or more, usually 2 to 1000. Preferably 5-200
is desirable and has a substantially linear structure.

The copolymer used in the present invention is colorless and transparent in a neutral state (when decolored), and becomes blue in an oxidized state (when colored).

Furthermore, the copolymer used in the present invention is soluble in solvents such as N-methylpyrrolidone, nitrobenzene, chloroform, and sulfuric acid, but is soluble in alcohols, aliphatic hydrocarbons, and acetonitrile used in electrolytes for EC devices. It is insoluble in propylene carbonate, etc., has excellent processability, and can be made into various molded products of any shape.

Furthermore, the copolymer used in the present invention has a property that when doped with anions, the nitrogen electrons in the copolymer become positively charged and become stable, so it is stable against repeated redox reactions. Moreover, by utilizing the characteristics of high conductivity and excellent processability as mentioned above, EC has no color unevenness and has excellent repeatability of decoloring and coloring.
You can create elements.

An electrochromic device using the electrochromic material of the present invention consists of an ECT electrode using a copolymer represented by general formula (I), an electrolyte, and a counter electrode.

For the above EC electrode, a copolymer represented by the general formula (I) of the present invention is dissolved in a solvent such as N-methylpyrrolidone, nitrobenzene, chloroform, sulfuric acid, etc., and a thin film is formed on the S electrode by a method such as a spin code. Shape it and then shape it, or
The copolymer represented by the general formula (I) of the present invention is heated and melted and molded, or the copolymer represented by the general formula (I) of the present invention is mixed with a binder to form an arbitrary shape. It is made by

Examples of the binder include polytetrafluoroethylene, polyvinylidene fluoride, polyvinyl chloride, polyethylene, etc., but are not necessarily limited to these.

Electrolytes that can be used in the present invention include liquid electrolytes and solid electrolytes.

The above liquid electrolytes (mainly composed of a solvent and an electrolyte compound, the solvent has a high dielectric constant and dissolves the electrolyte compound well, such as acetonitrile, benzonitrile, propylene carbonate, alcohol, acetone, nitromethane, Examples include ethyl acetate, pyridine, dioxane, water, etc. Examples of the electrolyte compounds include LiCIO4, LiBF4.NH4Cl0., (CH
3), NCI, (C2H5)4NCI, (C2H5
)4NBr, (C2H6)NCN, (C2H5)4NC
IO,, (C2H5)4NBF4. (C4H51NC
IO,, (C4H9), NBF4. (C4H9), 1
NH3o4. AgClO4, AgBF4. HCI, HB
Among them, those soluble in the solvent used are usually selected.

In addition to the liquid electrolyte described above, it is also preferable to use a solid polymer electrolyte.

The copolymer used in the present invention is colorless and transparent when decolored (neutral state), and becomes blue when colored (oxidized state). For this reason, when an EC element is created by combining WOo, etc., which shows blue coloration upon reduction, as a counter electrode, the hues at the time of coloring match, so when the electrode is applied (coloring), blue coloring occurs with high contrast, and it is roughly OV or Since it becomes colorless and transparent when a reverse voltage is applied, it also has excellent properties as a light control element.

That is, as the counter electrode, for example, WO9, Mo0,
EC materials that develop color upon reduction, such as Tie, NbO5, or transparent conductive glass coated with indium oxide, tin oxide, indium tin oxide, etc., may be used as is, or metals such as gold, platinum, and aluminum may be used. May be used.

(Effects of the Invention) The EC material of the present invention has reversible redox properties and can be formed into a uniform thin film, so it has excellent processability. Therefore, the EC element using the EC material of the present invention has high contrast, no color unevenness, and excellent repeatability of color development and fading.

(Examples) Hereinafter, the present invention will be specifically explained using Examples, but the present invention is not limited thereto.

Example 1 N, N'-
Add 1.0 g of dimethyl-N,N'-diphenyl-p-phenyl diamine, add 15 ml of nitrobenzene and dissolve it, then add 80 μl of Eaton's reagent and 1.5 ml of acetaldehyde and react at 80°C for 5 hours. I let it happen. The reaction solution was diluted with 1N NaOH aqueous solution 30I! The mixture was poured into 300 ml of ethanol containing I/O, and the off-white precipitate was filtered, washed with ethanol and distilled water, and dried to obtain 095 g of off-white powder. 'H-NMR, 13C-NM of the obtained powder
When RIR (Figure 1) was measured, an N,N'dimethyl-N,N'-diphenyl-p-phenyl diamine-p-paraaldehyde condensation polymer having the following structure (degree of polymerization of about 1) was found.
0).

The copolymer obtained in the above operation was dissolved in a chloroform/toluene mixture (chloroform/toluene = 4/1) to make a 1% by weight solution, and the solution was mixed with 5cm x 5an of ITO.
Gala X (Indiu+m Tin0xide glass)
A transparent electrode with a 15 μm thick copolymer layer was obtained by spin-coding onto a current collector and drying at room temperature under a nitrogen atmosphere.

ITO glass is used as the counter electrode of the above electrode, and a 4% degree IIIIol/l lithium perchlorate/propylene carbonate solution is sealed between the above electrode and the counter electrode,
An electrochromic display device as shown in FIG. 2 was prepared.

When a voltage of 2 volts was applied with the electrode of this display element positive and the counter electrode negative, the color changed from colorless to blue in about 3 seconds at room temperature. Next, when the counter electrode was reversed and a voltage of 2 volts was applied, it turned colorless in about 3 seconds. This colorless-
→The cycle of blue change was repeated 1000 times, but no deterioration in color tone was observed.

Example 2 The copolymer obtained in Example 1 was dissolved in a chloroform/toluene mixture (chloroform/toluene = 471) to make a 1% by weight solution, and the solution was 5cr1) x 5(
A transparent electrode having a copolymer layer with a thickness of 15 μm was obtained by spin-coating the ITO glass current collector of 2) and drying it at room temperature under a nitrogen atmosphere.

Next, WO was deposited on the ITO glass to form a layer with a thickness of 3000 A, which was used as a counter electrode.

Between the above electrode and the counter electrode, 80% lithium perchlorate containing 8% by weight of lithium perchlorate, which is mainly composed of a polyether compound, is placed between the above electrode and the counter electrode.
An electrochromic display element shown in FIG. 3 was prepared by sandwiching a .mu.m solid polymer electrolyte film.

When a voltage of 15 volts was applied with the electrode of this display element positive and the counter electrode negative, the color changed from colorless to blue in about 30 seconds at room temperature. Next, when the opposite electrode was reversed and a voltage of 15 volts was applied, it turned colorless in about 30 seconds. This cycle of colorless to -blue color change was repeated 1000 times, but no deterioration in color tone was observed.

Example 3 N, N'- in a nitrogen-substituted Loom/Mitsuro flask
After adding 15mt' of nitrobenzene and dissolving it, 1.5+ml of acetaldehyde (80 μl of Eaton's reagent) was added and reacted at 80° C. for 4 hours. The reaction solution was poured into 300+ ml of ethanol containing 301 ml of 1N NaOH aqueous solution, and the off-white precipitate was filtered, washed with ethanol and distilled water, and dried to obtain 095 g of off-white powder. 'H-NMR1)3C-N of the obtained powder
According to MRI8 measurement, N, N' has the following structure.
It turned out to be a -trimethyl N,N'-diphenyl-p-phenylenediamine-paraldehyde condensation polymer (degree of polymerization of about 50).

An EC display element was produced in the same manner as in Example 1 using the copolymer obtained in the above procedure.

When a voltage of 2 volts was applied with the electrode of this display element positive and the opposite electrode negative, the color changed from colorless to blue in about 3 seconds at room temperature, and then the opposite electrode was reversed and a voltage of 2 volts was applied. However, it turned colorless in about 3 seconds.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the infrared absorption spectrum of the condensation polymer obtained in Example 1 of the present invention. FIG. 2 is a cross-sectional view of the electrochromic device obtained in Example 1 of the present invention. FIG. 3 is a sectional view of an electrochromic device obtained in Example 2 of the present invention. 1-[TO glass 2 Electrolyte 3- Copolymer 4 Spacer 5...-ITO glass 6, WO layer 7, Polymer solid electrolyte film 8--Copolymer layer 9... Spacer

Claims (3)

[Claims] (1) General formula (I) ▲Mathematical formulas, chemical formulas, tables, etc.▼(I) (In the formula, R^1 is H or a hydrocarbon residue with 1 to 20 carbon atoms, R^2 is H, the number of carbon atoms 1 to 20 hydrocarbon residues, furyl group, pyridyl group, nitrophenyl group, chlorophenyl group or methoxyphenyl group, l is an integer of 2 or more, m is an integer of 1 or more, and n is an integer of 2 or more, respectively. An electrochromic material whose constituent component is a copolymer represented by (2) An electrochromic element comprising an electrode, an electrolyte, and a counter electrode formed by coating the electrochromic material according to claim 1 on a current collector. (3) The electrochromic element according to claim 2, wherein the counter electrode is an electrochromic material that develops color upon reduction.