JP2011081194A - Display element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display element which has simple member configuration, which can be driven at low voltage and has excellent reflectance stability in repetitive drive. <P>SOLUTION: The display element contains an electrochromic compound and an electrolyte between at least a pair of opposed electrodes, and the electrolyte contains a compound expressed by general formula (1). In the formula, X is a sulfur atom or an oxygen atom, and at least one X in the compound is the sulfur atom. (n) and (m) each are integers that are 1 or more and 10 or less, and (a) is an integer that is 1 or more and 50 or less. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a novel electrochemical display element.

  In recent years, with the increase in the operating speed of personal computers, the spread of network infrastructure, the increase in capacity and price of data storage, information such as documents and images provided on printed paper on paper has become easier to use electronic information. Opportunities to obtain and browse electronic information are increasing more and more.

  As a means for browsing such electronic information, a conventional liquid crystal display or CRT, and in recent years, a light emitting type such as an organic EL display is mainly used. In particular, when the electronic information is document information, it is relatively long time. It is necessary to pay close attention to this browsing means, and these actions are not necessarily human-friendly means. Generally, as a drawback of light-emitting displays, eyes flicker due to flickering, inconvenient to carry, reading posture is limited It is known that it is necessary to adjust the line of sight to a still screen, and that power consumption increases when read for a long time.

  As a display means to compensate for these drawbacks, a reflection type display using so-called "memory" that uses external light and does not consume power for image retention is known. However, it has sufficient performance for the following reasons. It is hard to say that it has.

  That is, the method using a polarizing plate such as a reflective liquid crystal has a low reflectance of about 40%, which makes it difficult to display white, and it is difficult to say that many of the manufacturing methods used to manufacture the constituent members are simple. In addition, the polymer dispersed liquid crystal requires a high voltage and utilizes the difference in refractive index between organic substances, so that the resulting image has insufficient contrast. In addition, the polymer network type liquid crystal has problems such as a high voltage and a complicated TFT circuit required to improve the memory performance. In addition, a display element based on electrophoresis requires a high voltage of 10 V or more, and there is a concern about durability due to electrophoretic particle aggregation.

  An electrochromic display element (hereinafter abbreviated as EC method) is known as a display method that eliminates the drawbacks of each of the above-described methods. The EC method is capable of full color display at a low voltage of 3 V or less, has advantages such as a simple cell configuration and excellent white quality, and various methods have been disclosed (for example, see Patent Documents 1 and 2). .

  As a result of a detailed study of the techniques disclosed in the above-mentioned patent documents, the present inventor has found that, in the prior art, the reflectance stability during white display and coloring during repeated driving (hereinafter referred to as driving stability). ) Proved to be a problem.

  As a means for solving this, there is a technique for removing metal ions present as impurities in the solvent by passing a solvent used in the electrolytic solution in advance through an ion exchange resin (for example, see Patent Document 3). In this technique, the ions of the ion exchange resin are eluted into the solvent, so the total amount of metal ions present as impurities in the solvent does not decrease, and the impurities contained in the additive used in the electrolyte are mixed into the electrolyte. It has been found that this method is not effective and does not lead to improved durability.

WO2004 / 068231 pamphlet WO2004 / 066773 pamphlet JP 2006-199646 A

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a display element that has a simple member structure, can be driven at a low voltage, and has excellent reflectance stability in repeated driving.

  The above object of the present invention can be achieved by the following configuration.

  1. A display element comprising an electrochromic compound and an electrolyte between at least a pair of opposing electrodes, wherein the electrolyte contains a compound represented by the following general formula (1).

(In the formula, X represents a sulfur atom or an oxygen atom, and at least one X in the compound is a sulfur atom. N and m are each an integer of 1 to 10, and a is an integer of 1 to 50. R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ each represents a substituent that does not have a dissociable proton, one of which includes a carbonyl group. Or may be linked to each other to form a cyclic structure. [] Represents a repeating unit, and when it is repeated, the atoms represented by X may be different from each other. In that case, R ₁ and R ₂ may also be different from each other, and the integer represented by m may also be different.)
2. 2. The display element according to 1 above, wherein n and m in the compound represented by the general formula (1) are 2 or 3, respectively.

  3. 3. The display element according to 1 or 2, wherein a in the compound represented by the general formula (1) is 2 or 3.

  4). 4. The display element according to any one of 1 to 3, wherein the electrolyte contains a metallocene compound.

  5. 5. The display element according to any one of 1 to 4, wherein the electrolyte contains a compound represented by the following general formula (F).

(Wherein R _{f1 to} R _f4 each represent hydrogen, a linear or branched alkyl group, a phenyl group, a benzyl group, an alkoxy group, or an alkylthio group, and each group may further have a substituent. R _f1 and R _f2 , R _f3 and R _f4 may form a ring, and Y ₁ and Y ₂ are S or Se, respectively.
6). 6. The display element according to any one of 1 to 5, wherein the electrochromic compound is represented by the following general formula (L).

(In the formula, Rl ₁ represents a substituted or unsubstituted aryl group, Rl ₂ and Rl ₃ each represent a hydrogen atom or a substituent. Xl represents> N-Rl ₄ , an oxygen atom or a sulfur atom, and Rl ₄ Represents a hydrogen atom or a substituent.)

  According to the present invention, it is possible to provide a display element that has a simple member configuration, can be driven at a low voltage, and has excellent reflectance stability in repeated driving.

  In the present invention, the compound represented by the general formula (1) is added to the electrolyte to form a complex with the metal ions present as impurities contained in the electrolyte, thereby reducing adverse effects caused by the metal ions present as impurities. It is a technology that improves stability. As a compound that forms a complex with a metal ion that exists as an impurity, it is preferable that the compound has a high ability to interact with the metal and is difficult to be oxidized / reduced by the compound itself. In that respect, in the general formula (1) according to the present invention, The compounds represented have excellent characteristics. Moreover, when an oxidation-reduction compound such as metallocene and fulvalene is added to the electrolytic solution to which the general formula (1) is added, decomposition due to repeated driving of the electrochromic compound can be suppressed, and driving stability can be further improved. This technique is a technique in which the improvement effect is greater as the concentration of metal ions present as impurities in the electrolytic solution is lower.

  Hereinafter, the best mode for carrying out the present invention will be described in detail, but the present invention is not limited thereto.

[Basic structure of display element]
The basic structure of the display element of the present invention will be described with reference to FIG. In the display element of the present invention, the display unit is provided with at least one pair of counter electrodes. The electrode 1 which is one of the counter electrodes close to the display unit is provided with a transparent electrode such as an ITO electrode, and the other electrode 2 is provided with a conductive electrode. Between the electrode 1 and the electrode 2, it has the electrolyte and the electrochromic compound containing the compound represented by General formula (1) based on this invention. By applying positive and negative voltages between the counter electrodes, white display and colored display can be switched reversibly.

[Compound represented by the general formula (1)]
The compound represented by the general formula (1) according to the present invention is a technique for improving driving stability by forming a complex with a metal ion present as an impurity in an electrolyte. Heterocyclic thiol compounds such as mercaptoazole are often used as compounds that form complexes with metal ions. Compared with these known compounds, structural features are said to interact with metal ions in the alkyl chain. This is in that a sulfur atom is incorporated, which has at least one carbonyl group which is also supposed to interact with a metal ion, and a dissociable proton is excluded.

  The compound represented by the general formula (1) according to the present invention is a compound having a thioether chain and at least one carbonyl group, and the thioether chain accounts for 30 to 99% by mass of the entire compound, It is a compound that does not have a dissociable proton.

  As a result of the study by the present inventors, by using such a specific structure, the corrosive force of the compound itself can be suppressed, and a sulfur atom and a carbonyl group are arranged to increase the interaction force with the metal ion. As a result, the corrosion of the electrode was greatly suppressed, the stability during repeated driving was excellent, and the rewriting speed during low voltage driving was further improved. Although the detailed mechanism is unknown, it is speculated that the significant improvement in electrode corrosion is due to the elimination of dissociable protons from the system.

  The compound represented by the general formula (1) according to the present invention preferably has a thioether chain.

In the general formula (1), the substituent represented by R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ is a substituent that does not have a dissociative proton. Groups.

  A halogen atom (eg, fluorine atom, chlorine atom, bromine atom, iodine atom), an alkyl group (eg, methyl, ethyl, propyl, i-propyl, butyl, t-butyl, pentyl, cyclopentyl, hexyl, cyclohexyl, octyl, Dodecyl, hydroxyethyl, methoxyethyl, trifluoromethyl, benzyl etc.), aryl group (eg phenyl, naphthyl etc.), alkoxy group (eg methoxy group, ethoxy group, propoxy group, 2-propoxy group, butoxy group, t -Butoxy group, pentyloxy group, 2-ethylhexyloxy group, trifluoromethoxy group, etc.), dialkylamino group (eg, dimethylamino group, diethylamino group, dibutylamino group etc.), diarylamino group (eg, diphenylamino group, A ditolylamino group, Mesitylamino group etc.), aryloxy group (eg phenoxy etc.), alkylthio group (eg methylthio, ethylthio, butylthio etc.), arylthio group (eg phenylthio group, tolylthio group etc.), dialkylcarbamoyl group (eg dimethylcarbamoyl, etc.) Diethylcarbamoyl, dibutylcarbamoyl, etc.), diarylcarbamoyl groups (eg, diphenylcarbamoyl, methylphenylcarbamoyl, ethylphenylcarbamoyl, benzylphenylcarbamoyl, etc.), dialkylsulfamoyl groups (eg, dimethylsulfamoyl, diethylsulfamoyl, dibutyl) Sulfamoyl, etc.), diarylsulfamoyl groups (for example, diphenylsulfamoyl, methylphenylsulfamoyl, ethylphenylsulfa Yl, benzylphenylsulfamoyl etc.), alkylsulfonyl group (eg methanesulfonyl group, ethanesulfonyl group etc.), arylsulfonyl group (eg phenylsulfonyl, 4-chlorophenylsulfonyl, p-toluenesulfonyl etc.), alkoxycarbonyl group (Eg, methoxycarbonyl, ethoxycarbonyl, butoxycarbonyl, etc.), aryloxycarbonyl groups (eg, phenoxycarbonyl, etc.), alkylcarbonyl groups (eg, acetyl, propionyl, butyroyl, etc.), arylcarbonyl groups (eg, benzoyl group, alkylbenzoyl) Group), dialkylaminocarbonyl group (eg, dimethylaminocarbonyl group, diethylaminocarbonyl group, etc.), diarylaminocarbonyl group (eg, diphenyl). Aminocarbonyl group, ditolylaminocarbonyl group, etc.), acyloxy group (eg, acetyloxy group, propionyloxy group, butyroyloxy group, etc.), carbonyl group, cyano group, or heterocyclic group (eg, oxazole ring, thiazole ring, triazole) Ring, selenazole ring, tetrazole ring, oxadiazole ring, thiadiazole ring, thiazine ring, triazine ring, benzoxazole ring, benzthiazole ring, indolenine ring, benzselenazole ring, naphthothiazole ring, triazaindolizine ring, dia A zaindolizine ring, a tetraazaindolizine ring group, etc.), preferably a halogen atom, an alkyl group, an alkoxy group, an alkylthio group, an acyl group, and a cyano group, more preferably an alkyl group and an alkoxy group. , Archi Thio, or a cyano group. These substituents may further have a substituent and may be linked to each other to form a condensed ring.

  In the general formula (1), X represents a sulfur atom or an oxygen atom, and at least one X in the compound is a sulfur atom.

  In general formula (1), a represents the number of repeating units. In order to have moderate solubility, it is preferably 1 to 50, preferably 1 to 10. More preferably, it is 1-6.

  [] Represents a repeating unit, and when a represents a number of 2 or more, a plurality of Xs are present, and in this case, Xs may be the same or different, and contain a sulfur atom. The larger the amount, the better. The integer represented by m may be the same or different.

In the above case, a plurality of R ₁ and R ₂ are also present, and in that case, they may be the same or different.

  In general formula (1) which concerns on this invention, content of a thioether chain | strand is 30-99 mass% of the whole compound. Preferably it is 33-85 mass%. Here, the content of the thioether chain refers to the mass% of the whole unit when the X of the unit represented by the general formula (1) is a sulfur atom with respect to the molecular weight of the whole compound.

For example, in the exemplified compound (1) -1 below, the thioether chain has a molecular weight of 120 (SC ₂ H ₄ ) ₂ and the entire molecule is 266, so that it is calculated as 120/266 × 100 = 45 mass%.

Specific examples of the group having a dissociable proton that the compound represented by the general formula (1) according to the present invention does not have include a hydroxyl group, a sulfo group, a carboxyl group, a sulfato group, and —CONHSO _2. - group (sulfonylcarbamoyl group, a carbonyl sulfamoyl group), - CONHCO- group (carbonylation carbamoyl _group), - SO 2 NHSO ₂ - group (sulfonylsulfamoyl group), a sulfamoyl group, phosphato group, a phosphono group, a boronic acid Depending on the pka and the surrounding pH, such as a group and a phenolic hydroxyl group, a group from which a proton is dissociated may be mentioned.

  The compound represented by the general formula (1) according to the present invention does not have such a group having a dissociative proton as a whole molecule such as a thioether chain, a terminal group, and a linking group.

The compound represented by the general formula (1) according to the present invention has at least one carbonyl group. This carbonyl group is preferably present as a terminal group of the compound or as a substituent of the thioether chain or a linking group of the terminal group and the thioether chain. It is preferable that R ₅ and R ₆ have the carbonyl group.

  The number of carbonyl groups is preferably 1 to 10, preferably 2 to 6 in one molecule. The terminal group is preferably a group having no dissociable proton such as an alkyl group, an alkenyl group, and an aryl group.

  In the compound represented by the general formula (1) according to the present invention, the carbonyl group and the thioether chain are bonded directly or through a linking group. The linking group is preferably divalent to tetravalent. The linking group is a group that does not have a dissociable proton.

  The amount of the thioether compound used is generally 30 mol / L or less, preferably 20 mol / L or less, more preferably 10 mol / L or less as the upper limit in the solvent constituting the electrolyte layer. Desirably, the lower limit is usually 0.01 mol / L or more, preferably 0.05 mol / L or more.

  The preferable specific example of a compound represented by General formula (1) based on this invention is shown.

[Electrochromic compound]
The electrochromic compound according to the present invention is not particularly limited as long as it exhibits an action of color development or decoloration by an electrochemical oxidation reaction and reduction reaction, and can be appropriately selected according to the purpose. Such electrochromic compounds include tungsten oxide, iridium oxide, nickel oxide, cobalt oxide, vanadium oxide, molybdenum oxide, titanium oxide, indium oxide, chromium oxide, manganese oxide, Prussian blue, indium nitride, tin nitride, nitride nitride In addition to inorganic compounds such as zirconium, conductive polymer compounds and organic dyes are known.

  Examples of the conductive polymer compound exhibiting electrochromic characteristics include polypyrrole, polythiophene, polyisothianaphthene, polyaniline, polyphenylenediamine, polybenzidine, polyaminophenol, polyvinylcarbazole, polycarbazole, and derivatives thereof.

  Examples of organic dyes that exhibit electrochromic properties include pyridinium compounds such as viologen, azine dyes such as phenothiazine, styryl dyes, anthraquinone dyes, pyrazoline dyes, fluorane dyes, donor / acceptor compounds (for example, tetracyanoquino compounds) Dimethane, tetrathiafulvalene) and the like. In addition, compounds known as redox indicators and pH indicators can be used.

  When electrochromic compounds are classified in terms of color change, they can be divided into the following three classes.

  Class 1: An electrochromic compound that changes from one specific color to another by redox.

  Class 2: An electrochromic compound that is substantially colorless in an oxidized state and exhibits a specific colored state that is a reduced state.

  Class 3: An electrochromic compound that is substantially colorless in the reduced state and exhibits a specific colored state that is an oxidized state.

  In the display element of the present invention, the class 1 to class 3 electrochromic compounds can be appropriately selected depending on the purpose and application.

[Class 1 electrochromic compound]
A class 1 electrochromic compound is an electrochromic compound that changes from a specific color to another color by oxidation-reduction, and is a compound that can display two or more colors in its possible oxidation state.

As compounds classified into class 1, for example, V ₂ O ₅ changes from orange to green by changing from an oxidized state to a reduced state, and similarly Ru ₂ O ₃ changes from yellow to dark green.

  Many of the conductive polymers are also classified as class 1. For example, polythiophene changes from blue to red by changing from an oxidized state to a reduced state, and polypyrrole changes from brown to yellow. In addition, polyaniline or the like exhibits multi-color characteristics and changes from an amber color of an oxidation state to blue, green, and light yellow in order.

  An electrochromic compound classified as class 1 has a merit that multicolor display is possible with a single compound, but has a disadvantage that it cannot be said to be substantially colorless.

[Class 2 electrochromic compounds]
Class 2 electrochromic compounds are compounds that are colorless or extremely light in an oxidized state and exhibit a specific colored state that is a reduced state.

Examples of the inorganic compounds classified as class 2 include the following compounds, each of which shows the color shown in parentheses in the reduced state. WO ₃ (blue), MnO ₃ (blue), Nb ₂ O ₅ (blue), TiO ₂ (blue) and the like.

  Examples of organic dyes classified into class 2 include compounds described in JP-A-62-71934, JP-A-2006-71765, etc., such as dimethyl terephthalate (red), diethyl 4,4′-biphenylcarboxylate (yellow). ), 1,4-diacetylbenzene (cyan), or tetrazolium salt compounds described in JP-A-1-230026, JP-T 2000-504964, and the like.

  The most representative dyes classified into class 2 are pyridinium compounds such as viologen. Viologen compounds have the advantages of vivid display and color variations by changing the substituents, etc., so they are the most actively studied among organic dyes. ing. Color development is based on organic radicals generated by reduction.

  Examples of pyridinium-based compounds such as viologen include compounds described in the following patents, including, for example, Special Table 2000-506629.

  JP-A-5-70455, JP-A-5-170738, JP-A-2000-235198, JP-A-2001-114769, JP-A-2001-172293, JP-A-2001-181293, JP-A-2001-181590, JP-A-2001-510590, JP-A-2001-510590 2004-101729, JP 2006-154683, JP 2006-519222, JP 2007-31708, 2007-171781, 2007-219271, 2007-219272, JP 2007-279659, JP 2007-279570, JP 2007- 279571, Japanese Patent Application Laid-Open No. 2007-279572, and the like.

  Examples of pyridinium compounds such as viologen that can be used in the present invention are shown below, but are not limited thereto.

[Class 3 electrochromic compounds]
A class 3 electrochromic compound is a compound that is colorless or extremely light in a reduced state and exhibits a specific colored state that is an oxidized state.

  Examples of inorganic compounds classified as class 3 include iridium oxide (dark blue), Prussian blue (blue), and the like (each of which shows the color shown in parentheses in the oxidized state).

  There are few examples of conductive polymers classified into class 3, but for example, phenyl ether compounds described in JP-A-6-263846 can be mentioned.

  Many dyes are known as class 3 dyes, styryl dyes, azine dyes such as phenazine, phenothiazine, phenoxazine, and acridine, azole dyes such as imidazole, oxazole, and thiazole are preferable. .

  Examples of styryl dyes, azine dyes, and azole dyes that can be used in the present invention are shown below, but are not limited thereto.

  In a preferred embodiment of the present invention, a metal salt that is reversibly dissolved and precipitated by an electrochemical oxidation-reduction reaction is used in combination with the electrochromic dye, and three or more colors of black display, white display, and color display other than black are used. Multi-color display. In this case, since the metal salt is reduced and black display is performed, the electrochromic dye is preferably a class 3 electrochromic compound that develops color by oxidation, particularly in terms of color development diversity, low driving voltage, memory properties, and the like. An azole dye is preferred. In the present invention, the most preferred dye is a compound represented by the general formula (L).

In the general formula (L), Rl ₁ represents a substituted or unsubstituted aryl group, and Rl ₂ and Rl ₃ each represent a hydrogen atom or a substituent. X represents> N—Rl ₄ , an oxygen atom or a sulfur atom, and Rl ₄ represents a hydrogen atom or a substituent.

When Rl ₁ represents an aryl group having a substituent, the substituent is not particularly limited, and examples thereof include the following substituents.

  Alkyl groups (eg, methyl, ethyl, propyl, isopropyl, tert-butyl, pentyl, hexyl, etc.), cycloalkyl groups (eg, cyclohexyl, cyclopentyl, etc.), alkenyl groups, cycloalkenyl groups , Alkynyl groups (for example, propargyl group), glycidyl groups, acrylate groups, methacrylate groups, aromatic groups (for example, phenyl group, naphthyl group, anthracenyl group, etc.), heterocyclic groups (for example, pyridyl group, thiazolyl group, oxazolyl group) Group, imidazolyl group, furyl group, pyrrolyl group, pyrazinyl group, pyrimidinyl group, pyridazinyl group, selenazolyl group, sriphoranyl group, piperidinyl group, pyrazolyl group, tetrazolyl group, etc.), alkoxy group (for example, methoxy group, ethoxy group, propyloxy) Group, pliers Oxy group, cyclopentyloxy group, hexyloxy group, cyclohexyloxy group, etc.), aryloxy group (eg, phenoxy group, etc.), alkoxycarbonyl group (eg, methyloxycarbonyl group, ethyloxycarbonyl group, butyloxycarbonyl group, etc.) , Aryloxycarbonyl group (for example, phenyloxycarbonyl group), sulfonamide group (for example, methanesulfonamide group, ethanesulfonamide group, butanesulfonamide group, hexanesulfonamide group, cyclohexanesulfonamide group, benzenesulfonamide group ), Sulfamoyl group (for example, aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylamino) Sulfonyl group, phenylaminosulfonyl group, 2-pyridylaminosulfonyl group, etc.), urethane group (for example, methylureido group, ethylureido group, pentylureido group, cyclohexylureido group, phenylureido group, 2-pyridylureido group, etc.), acyl Groups (eg, acetyl, propionyl, butanoyl, hexanoyl, cyclohexanoyl, benzoyl, pyridinoyl, etc.), carbamoyl groups (eg, aminocarbonyl, methylaminocarbonyl, dimethylaminocarbonyl, propylamino) Carbonyl group, pentylaminocarbonyl group, cyclohexylaminocarbonyl group, phenylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), acylamino group (for example, acetylamino group, benzoyla) Mino group, methylureido group, etc.), sulfonyl group (eg, methylsulfonyl group, ethylsulfonyl group, butylsulfonyl group, cyclohexylsulfonyl group, phenylsulfonyl group, 2-pyridylsulfonyl group, etc.), amino group (eg, amino group, Ethylamino group, dimethylamino group, butylamino group, cyclopentylamino group, anilino group, 2-pyridylamino group, etc.), halogen atom (eg chlorine atom, bromine atom, iodine atom etc.), cyano group, nitro group, sulfo group Carboxyl group, hydroxyl group, phosphono group (for example, phosphonoethyl group, phosphonopropyl group, phosphonooxyethyl group) and the like. Further, these groups may be further substituted with these groups.

Rl ₁ is preferably a substituted or unsubstituted phenyl group, more preferably a substituted or unsubstituted 2-hydroxyphenyl group or 4-hydroxyphenyl group.

Rl _2, Rl is not particularly limited as substituent represented by _3, etc. substituents exemplified as a substituent on the aryl group of the Rl ₁ can be mentioned. Rl ₂ and Rl ₃ are preferably an alkyl group, a cycloalkyl group, an aromatic group, or a heterocyclic group, which may have a substituent. Rl ₂ and Rl ₃ may be connected to each other to form a ring structure. As a combination of Rl ₂ and Rl ₃ , both of them may be a phenyl group or a heterocyclic group which may have a substituent, or one of them may be a phenyl group or a heterocyclic group which may have a substituent. Yes, the other is a combination of alkyl groups which may have a substituent.

X is preferably a> N-Rl _4. Rl ₄ is preferably a hydrogen atom, an alkyl group, an aromatic group, a heterocyclic group or an acyl group, more preferably a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an aryl group having 5 to 10 carbon atoms, or acyl. It is a group.

In the display element of the present invention, it is preferable that the compound represented by the general formula (L) according to the present invention has a group that chemically or physically adsorbs on the electrode surface. The chemical adsorption according to the present invention is a relatively strong adsorption state due to a chemical bond with the electrode surface, and the physical adsorption according to the present invention is a relatively strong van der Waals force acting between the electrode surface and the adsorbed substance. It is weakly adsorbed. The adsorptive group according to the present invention is preferably a chemisorbable group. Examples of the adsorptive group to be chemisorbed include —COOH, —P═O (OH) ₂ , —OP═O (OH) ₂ and -Si (OR) ₃ (R represents an alkyl group) is preferable.

  Among the azole dyes represented by the general formula (L), an imidazole dye represented by the following general formula (L2) is particularly preferable.

In the general formula (L2), Rl ₂₁ and Rl ₂₂ represent an aliphatic group, an aliphatic oxy group, an acylamino group, a carbamoyl group, an acyl group, a sulfonamide group, and a sulfamoyl group, and Rl ₂₃ represents an aromatic group or an aromatic group. Rl ₂₄ represents a hydrogen atom, an aliphatic group, an aromatic group or an aromatic heterocyclic group, and RL ₂₅ represents a hydrogen atom, an aliphatic group, an aromatic group or an acyl group.

These groups represented by Rl ₂₁ to Rl ₂₅ may be further substituted with an arbitrary substituent. However, at least one of the groups represented by Rl ₂₁ to Rl ₂₅ has a partial structure of —COOH, —P═O (OH) 2, —OP═O (OH) 2 and —Si (OR) 3 (R Represents an alkyl group).

The group represented by the general formulas Rl ₂₁ and Rl ₂₂ is preferably an alkyl group (particularly a branched alkyl group), a cycloalkyl group, an alkyloxy group, or a cycloalkyloxy group. Rl ₂₃ is preferably a substituted or unsubstituted phenyl group, a 5-membered or 6-membered heterocyclic group (for example, thienyl group, furyl group, pyrrolyl group, pyridyl group, etc.). Rl ₂₄ is preferably a substituted or unsubstituted phenyl group, a 5-membered or 6-membered heterocyclic group, or an alkyl group. Rl ₂₅ is particularly preferably a hydrogen atom or an aryl group.

When fixing the general formula (L2) on the electrode, at least one of the groups represented by Rl ₂₁ to Rl ₂₅ has a partial structure of —P═O (OH) ₂ , —Si (OR) ₃ (R Represents an alkyl group, and particularly preferably has —Si (OR) ₃ as a partial structure of the group represented by Rl ₂₃ or Rl ₂₄ .

  Specific examples of the EC dye represented by the general formula (L2) and specific examples of the EC dye contained in the general formula (L) that do not correspond to the general formula (L2) are shown below. The invention is not limited to these exemplified compounds.

[Metalocene compounds]
As the metallocene compound according to the present invention, ferrocene derivatives, titanocene derivatives, zirconocene derivatives, and hafnocene derivatives can be used. A ferrocene derivative is preferably used as the metallocene derivative. Examples of the ferrocene derivative include ferrocene, methyl ferrocene, dimethyl ferrocene, ethyl ferrocene, propyl ferrocene, n-butyl ferrocene, t-butyl ferrocene, 1,1-dicarboxy ferrocene, and more preferably ferrocene. The metallocene compound is preferably in the range of +0.1 V or more and +0.5 V or less when a silver-silver nitrate electrode is used as a reference potential. The metallocene compounds can be used alone or in admixture of two or more. The addition amount of the metallocene compound is preferably in the range of 0.3 mol / L to 3 mol / L with respect to the electrolyte solvent. If the metallocene concentration is too low, the effect of improving the driving stability is small, and if it is too high, adverse effects such as a decrease in rewriting speed and a decrease in reflectance during white display occur.

[Compound represented by formula (F)]
R _{f1 to} R _f4 of the compound represented by the general formula (F) according to the present invention represent hydrogen, a linear or branched alkyl group, a phenyl group, a benzyl group, an alkoxy group, and an alkylthio group, respectively. The group may further have a substituent. R _f1 and R _f2 , R _f3 and R _f4 may form a ring. Y ₁ and Y ₂ are each S or Se, preferably at least one of Y ₁ and Y ₂ is S, and more preferably one of Y ₁ and Y ₂ is S. The compounds represented by formula (F) can be used alone or in admixture of two or more. The amount of the compound represented by the general formula (F) is preferably in the range of 0.3 mol / L to 3 mol / L with respect to the electrolyte solvent. If the concentration of the compound represented by the general formula (F) is too low, the effect of improving the driving stability is small, and if it is too high, problems such as a decrease in rewriting speed and a decrease in reflectance during white display occur. The compound represented by the general formula (F) is preferably used in combination with a metallocene compound.

  Next, although the preferable specific example of a compound represented by general formula (F) is shown, this invention is not limited to these compounds.

[Organic solvent]
In the electrolyte layer according to the present invention, as an organic solvent, various additives such as a metal salt compound and a promoter that are generally used in electrochemical cells and batteries and are reversibly dissolved and precipitated by an electrochemical redox reaction can be dissolved. A solvent can be used.

  Specifically, acetic anhydride, methanol, ethanol, tetrahydrofuran, ethylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, butylene carbonate, propylene carbonate, nitromethane, acetonitrile, acetylacetone, N-methylformamide, N, N-dimethylformamide , Dimethyl sulfoxide, hexamethylphosphoamide, dimethoxyethane, diethoxyfuran, γ-butyrolactone, γ-valerolactone, sulfolane, propionitrile, butyronitrile, glutaronitrile, adiponitrile, methoxyacetonitrile, N-methylacetamide, N, N -Dimethylacetamide, N-methylpropionamide, methylpyrrolidinone, 2- (N-methyl) -2-pyrrolidi Non, dimethyl sulfoxide, dioxolane, trimethyl phosphate, triethyl phosphate, tripropyl phosphate, ethyl dimethyl phosphate, tributyl phosphate, tripentyl phosphate, trihexyl phosphate, triheptyl phosphate, trioctyl phosphate, trinonyl phosphate, tridecyl phosphate, tris (Trifluoromethyl) phosphate, tris (pentafluoroethyl) phosphate, triphenyl phosphate, tricresyl phosphate, 2-ethylhexyl phosphate, tetramethylurea, 1,3-dimethyl-2-imidazolidinone, hexamethylphosphotriamide 4-methyl-2-pentanone, dioctyl phthalate, dioctyl sebacate, and ethylene glycol Lumpur, diethylene glycol, polyethylene glycols such as triethylene glycol monobutyl ether and the like can be used.

  Furthermore, room temperature molten salts can also be used as solvents. The room temperature molten salt is a salt composed of ion pairs that are melted at room temperature (that is, in a liquid state) consisting only of ion pairs that do not contain a solvent component, and usually has a melting point of 20 ° C. or lower, A salt consisting of an ion pair that is liquid at a temperature above. The room temperature molten salt can be used alone or in combination of two or more.

  The electrolyte solvent used in the present invention is preferably an aprotic polar solvent, particularly propylene carbonate, ethylene carbonate, dimethyl sulfoxide, dimethoxyethane, acetonitrile, γ-butyrolactone, sulfolane, dioxolane, dimethylformamide, dimethoxyethane, tetrahydrofuran, adiponitrile, Methoxyacetonitrile, dimethylacetamide, methylpyrrolidinone, dimethyl sulfoxide, dioxolane, sulfolane, trimethyl phosphate and triethyl phosphate are preferred. The solvent may be used alone or in combination of two or more.

  In the present invention, the solvent preferably used is a compound represented by the following general formula (S1) or (S2).

  <Compounds Represented by General Formulas (S1) and (S2)>

In the general formula (S1), L represents an oxygen atom or an alkylene group, and Rs ₁₁ to Rs ₁₄ each represents a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, a cycloalkyl group, an alkoxyalkyl group, or an alkoxy group.

In the general formula (S2), Rs ₂₁ and Rs ₂₂ each represents an alkyl group, an alkenyl group, an aryl group, a cycloalkyl group, an alkoxyalkyl group, or an alkoxy group.

  First, the detail of the compound represented by general formula (S1) is demonstrated.

In the general formula (S1), L represents an oxygen atom or CH ₂ , and Rs ₁₁ to Rs ₁₄ each represents a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, a cycloalkyl group, an alkoxyalkyl group, or an alkoxy group, These substituents may be further substituted with an arbitrary substituent.

  Examples of alkyl groups include methyl, ethyl, propyl, isopropyl, tert-butyl, pentyl, hexyl, octyl, dodecyl, tridecyl, tetradecyl, pentadecyl, and the like as aryl groups. Examples of the cycloalkyl group such as phenyl group, naphthyl group and the like include, for example, a cyclopentyl group, cyclohexyl group and the like, an alkoxyalkyl group, for example, a β-methoxyethyl group, a γ-methoxypropyl group and the like, as an alkoxy group, Examples thereof include a methoxy group, an ethoxy group, a propyloxy group, a pentyloxy group, a hexyloxy group, an octyloxy group, and a dodecyloxy group.

  Hereinafter, although the specific example of a compound represented by general formula (S1) is shown, in this invention, it is not limited only to these illustrated compounds.

  Next, details of the compound represented by formula (S2) according to the present invention will be described.

In the general formula (S2), Rs ₂₁ and Rs ₂₂ each represent a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, a cycloalkyl group, an alkoxyalkyl group, or an alkoxy group.

  Examples of alkyl groups include methyl, ethyl, propyl, isopropyl, tert-butyl, pentyl, hexyl, octyl, dodecyl, tridecyl, tetradecyl, pentadecyl, and the like as aryl groups. Examples of the cycloalkyl group such as phenyl group, naphthyl group and the like include, for example, a cyclopentyl group, cyclohexyl group and the like, an alkoxyalkyl group, for example, a β-methoxyethyl group, a γ-methoxypropyl group and the like, as an alkoxy group, Examples thereof include a methoxy group, an ethoxy group, a propyloxy group, a pentyloxy group, a hexyloxy group, an octyloxy group, and a dodecyloxy group.

  Hereinafter, although the specific example of a compound represented by general formula (S2) is shown, in this invention, it is not limited only to these illustrated compounds.

  Of the compounds represented by the general formulas (S1) and (S2) exemplified above, the exemplary compounds (S1-1), (S1-2), and (S2-3) are particularly preferable.

  The compounds represented by the general formulas (S1) and (S2) according to the present invention are one type of electrolyte solvent. However, in the display element of the present invention, another solvent is used as long as the object effects of the present invention are not impaired. Can be used together. Specifically, tetramethylurea, sulfolane, dimethyl sulfoxide, 1,3-dimethyl-2-imidazolidinone, 2- (N-methyl) -2-pyrrolidinone, hexamethylphosphortriamide, N-methylpropionamide, N, N-dimethylacetamide, N-methylacetamide, N, N dimethylformamide, N-methylformamide, butyronitrile, propionitrile, acetonitrile, acetylacetone, 4-methyl-2-pentanone, 2-butanol, 1-butanol, 2 -Propanol, 1-propanol, ethanol, methanol, acetic anhydride, ethyl acetate, ethyl propionate, dimethoxyethane, diethoxyfuran, tetrahydrofuran, ethylene glycol, diethylene glycol, triethylene glycol monobuty Ether, water and the like. Among these solvents, it is preferable to include at least one solvent having a freezing point of −20 ° C. or lower and a boiling point of 120 ° C. or higher.

  Furthermore, as a solvent which can be used in the present invention, J.P. A. Riddick, W.M. B. Bunger, T.A. K. Sakano, “Organic Solvents”, 4th ed. , John Wiley & Sons (1986). Marcus, “Ion Solvation”, John Wiley & Sons (1985), C.I. Reichardt, “Solvents and Solvent Effects in Chemistry”, 2nd ed. VCH (1988), G .; J. et al. Janz, R.A. P. T.A. Tomkins, “Nonqueous Electronics Handbook”, Vol. 1, Academic Press (1972).

  In the present invention, the electrolyte solvent may be a single type or a mixture of solvents, but a mixed solvent containing ethylene carbonate is preferred. The addition amount of ethylene carbonate is preferably 10% by mass or more and 90% by mass or less of the total electrolyte solvent mass. A particularly preferable electrolyte solvent is a mixed solvent having a mass ratio of propylene carbonate / ethylene carbonate of 7/3 to 3/7. When the propylene carbonate ratio is larger than 7/3, the ionic conductivity is inferior and the response speed is lowered. When the propylene carbonate ratio is smaller than 3/7, the electrolyte tends to be deposited at a low temperature.

[Oxidation auxiliary compound and reduction reaction type compound]
The electrolyte according to the present invention may contain an oxidation auxiliary compound or a reduction auxiliary compound.

  The oxidation auxiliary compound and the reduction auxiliary compound according to the present invention have an effect of assisting and stabilizing the reaction when the electrochromic compound is oxidized or reduced to develop a color.

(Oxidation auxiliary compound)
The oxidation auxiliary compound according to the present invention has an effect of assisting and stabilizing the color reaction of the electrochromic compound. By adding the oxidation auxiliary compound according to the present invention to the electrolyte, the oxidation reaction of the electrochromic compound is performed via this oxidation auxiliary compound, so that driving stability is improved. Preferred as the oxidation auxiliary compound according to the present invention is a compound that has an oxidation potential lower than the oxidation potential of the electrochromic compound and does not substantially color before and after the reaction or slightly color with the same color tone as the electrochromic compound.

  The oxidation potential as used in the present invention can be measured by a cyclic voltammogram.

Specifically, the cyclic voltammogram can be measured by, for example, the cyclic voltammetry method of an electrochemical analyzer ALS600C manufactured by BAS. For the measurement, a solution prepared by dissolving the oxidizing active compound according to the present invention and a supporting electrolyte such as tetrabutylammonium perchloride in an appropriate solvent, for example, acetonitrile, is prepared, and the RE-5 non-aqueous solvent reference electrode manufactured by BAS is referred to. A cyclic voltammogram can be measured under the conditions of an electrode (Ag / Ag ⁺ ), a Pt working electrode, a Pt counter electrode, and a scanning speed of 100 mV / sec.

  When a clear peak cannot be confirmed in the electrochromic compound, a potential at which coloring of the electrochromic compound starts to be confirmed can be read and used as an oxidation potential.

  As such oxidation assisting compounds, metallocene derivatives such as ferrocene, phenothiazine derivatives, or the compounds shown below are known. In the display element of the present invention, that is, in the system where an electrochromic compound is present, N- Compounds having an N—O bond of oxyl derivatives, N-hydroxyphthalimide derivatives, hydroxamic acid derivatives, and compounds having an allyloxy free group having a bulky substituent introduced at the O-position of galvinoxyl are effective. These compounds are very preferable because they all have a low oxidation potential and are hardly colored before and after the reaction.

  As N-oxyl derivatives, derivatives substituted with various substituents such as TEMPO (2,2,6,6-tetramethylpiperidinyl-N-oxyl) are commercially available. In addition, various derivatives including polymers can be easily synthesized according to known literature.

  In general, it is known that when hydrogen is substituted on the α-position carbon of the nitroxide radical, it is easily disproportionated to hydroxyamine and nitrone. For this reason, the four methyl groups at the N-oxyl group α-position of TEMPO can be said to be indispensable structures for existing as stable radicals, but conversely, the reactivity may decrease due to steric hindrance of these four methyl groups. is there. Azaadamantane N-oxyl derivatives or azabicyclo N-oxyl derivatives are preferred in that they do not cause a decrease in activity.

  N-hydroxyphthalimide (NHPI) and the like are known as N-hydroxyphthalimide derivatives.

  Examples of the hydroxamic acid derivative include trihydroxyimino cyanuric acid (THICA).

(Reduction auxiliary compound)
In the display element of the present invention, the effect of improving the memory property can be exhibited particularly by adding a reduction assisting compound to the electrolyte. When the electrochromic compound causes a color development reaction at the observation side electrode, surplus charges are generated at the non-observation side electrode. In the display element of the present invention, since the coloring and decoloring reaction of the electrochromic compound used is reversible, the decoloring reaction of the electrochromic compound occurs due to this excess charge when the application of voltage is stopped. . In response to the above problem, by adding a reduction auxiliary compound to the electrolyte, even if this surplus charge reacts with the reduction auxiliary compound and the application of voltage is stopped, the electrochromic decoloring reaction does not easily occur.

  As a reduction auxiliary compound suitable for the present invention, a compound that does not substantially color or slightly develops in the same color tone as electrochromic when a reduction reaction is caused is preferable. However, as will be described later, when a white scatterer is mixed with the electrolyte when used as a reflection type display element, the reaction at the non-observation side electrode is concealed by the white scatterer, so that it changes to a different color tone. Even things can be used.

  Examples of compounds effective as the reduction auxiliary compound according to the present invention include thianthrene derivatives, tetrathiafulvalene derivatives, tetracyanoquinodimethane derivatives, hydrazyl free radical compounds such as verdazil, thiazyl free radical compounds, hydrazone derivatives, and the like.

  Furthermore, more preferred reduction auxiliary compounds in the present invention include ethanedione derivatives, tetrazolium salts, formazan derivatives, phenazine derivatives, phenoxazine derivatives, acridine derivatives, and diphenylethanedione derivatives. All of these compounds exhibit good reversible reactivity.

[Supporting salt]
The electrolyte layer according to the present invention preferably contains a lithium salt. The lithium salt that can be used as the supporting electrolyte salt used in the present invention is not particularly limited. For example, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium bis (trifluoro) (Romethanesulfonyl) imide, lithium trifluoromethanesulfonate, lithium bisfluorosulfonylimide and the like can be used.

[White scattered matter]
In the present invention, a porous white scattering layer containing a white scattering material can be provided from the viewpoint of further increasing display contrast and white display reflectance.

  The porous white scattering layer applicable to the present invention can be formed by applying and drying an aqueous mixture of an aqueous polymer and a white pigment that is substantially insoluble in the electrolyte solvent.

  In the present invention, “substantially insoluble in an electrolyte solvent” is defined as a state in which the dissolved amount per kg of electrolyte solvent is 0 g or more and 10 g or less at a temperature of −20 ° C. to 120 ° C. The amount of dissolution can be determined by a known method such as a component determination method using a chromatogram or a gas chromatogram.

  In the present invention, examples of the water-based polymer that does not substantially dissolve in the electrolyte solvent include a water-soluble polymer and a polymer dispersed in the water-based solvent.

Examples of water-soluble polymers include proteins such as gelatin and gelatin derivatives or cellulose derivatives, natural compounds such as starch, gum arabic, dextran, pullulan, and carrageenan, and other natural compounds such as polyvinyl alcohol, polyethylene glycol, polyvinyl pyrrolidone, and acrylamide. Synthetic polymer compounds such as coalescence and derivatives thereof may be mentioned. Examples of gelatin derivatives include acetylated gelatin, phthalated gelatin, polyvinyl alcohol derivatives include terminal alkyl group-modified polyvinyl alcohol, terminal mercapto group-modified polyvinyl alcohol, and cellulose derivatives include hydroxyethyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose, and the like. It is done. Furthermore, Research Disclosure and those described in pages (71) to (75) of JP-A No. 64-13546, US Pat. No. 4,960,681, JP-A No. 62-245260, etc. superabsorbent polymers described, namely -COOM or -SO 3 M _(M is a hydrogen atom or an alkali metal) homopolymer or a vinyl monomer together or with other vinyl monomers (e.g., sodium methacrylate in the vinyl monomer having a methacrylic acid Copolymers with ammonium, potassium acrylate, etc.) are also used. These binders can be used in combination of two or more.

  In the present invention, polyvinyl alcohol, polyethylene glycol, and polyvinyl pyrrolidone compounds can be preferably used. In particular, the electrolyte layer preferably contains a polyethylene glycol compound. Examples of polyethylene glycol compounds include polyethylene glycols, polypropylene glycols, polyethylene glycol alkyl ethers, polypropylene glycol alkyl ethers, polyethylene glycol aryl ethers, polypropylene glycol aryl ethers, polyethylene glycol alkyl aryl ethers, polypropylene glycol alkyl. Aryl ethers, polyethylene glycol glycerol esters, polypropylene glycol glycerol esters, polyethylene sorbitol esters, polypropylene glycol sorbitol esters, polyethylene glycol fatty acid esters, polypropylene glycol fatty acid esters, polyethylene glycolated ethylenediamines Polypropylene glycolated ethylenediamines, polyethylene glycolated diethylenetriamine, and polypropylene glycol diethylenetriamines.

  Polymers dispersed in an aqueous solvent include latexes such as natural rubber latex, styrene butadiene rubber, butadiene rubber, nitrile rubber, chloroprene rubber, isoprene rubber, polyisocyanate, epoxy, acrylic, silicon, polyurethane, Examples thereof include a thermosetting resin in which urea, phenol, formaldehyde, epoxy-polyamide, melamine, alkyd resin, vinyl resin and the like are dispersed in an aqueous solvent. Of these polymers, it is preferable to use an aqueous polyurethane resin described in JP-A-10-76621.

  In the present invention, the average molecular weight of the water-based polymer is preferably in the range of 10,000 to 2,000,000, more preferably in the range of 30,000 to 500,000 in terms of weight average.

  Examples of the white pigment applicable in the present invention include titanium dioxide (anatase type or rutile type), barium sulfate, calcium carbonate, aluminum oxide, zinc oxide, magnesium oxide and zinc hydroxide, magnesium hydroxide, magnesium phosphate, Magnesium hydrogen phosphate, alkaline earth metal salt, talc, kaolin, zeolite, acidic clay, glass, organic compounds such as polyethylene, polystyrene, acrylic resin, ionomer, ethylene-vinyl acetate copolymer resin, benzoguanamine resin, urea-formalin resin, A melamine-formalin resin, a polyamide resin, or the like may be used alone or in combination, or in a state having voids that change the refractive index in the particles.

In the present invention, among the above white pigments, titanium dioxide is preferably used. In particular, titanium dioxide surface-treated with an inorganic oxide (Al ₂ O ₃ , AlO (OH), SiO _2, etc.), in addition to these surface treatments. Titanium dioxide that has been treated with an organic substance such as trimethylolethane, triethanolamine acetate, or trimethylcyclosilane is more preferably used.

  Of these white pigments, it is more preferable to use titanium oxide or zinc oxide from the viewpoint of coloring prevention at high temperature and the reflectance of the element due to the refractive index.

  In the present invention, the water mixture of the water-based compound and the white pigment is preferably in a form in which the white pigment is dispersed in water according to a known dispersion method. The mixing ratio of the aqueous compound / white pigment is preferably 1 to 0.01, more preferably 0.3 to 0.05 in terms of volume ratio.

  The thickness of the porous white scattering layer is preferably in the range of 5 to 50 μm, more preferably in the range of 10 to 30 μm.

  As the solvent, an alcohol solvent having high solubility in water such as methanol, ethanol, isopropanol is preferably used, and the mixing ratio of water / alcohol solvent is in the range of 0.5 to 20 in terms of mass ratio. More preferably, it is the range of 2-10.

  In the present invention, the medium for applying the water mixture of the water-based compound and the white pigment may be at any position as long as it is on the component between the counter electrodes of the display element, but on the electrode surface of at least one of the counter electrodes. It is preferable to give to.

  As a method for applying to a medium, for example, a coating method, a liquid spraying method, a spraying method via a gas phase, a method of flying droplets using vibration of a piezoelectric element, for example, a piezoelectric inkjet head, Examples thereof include a bubble jet (registered trademark) type ink jet head that causes droplets to fly using a thermal head that uses bumping, and a spray type that sprays liquid by air pressure or liquid pressure.

  As a coating method, it can select suitably from a well-known coating method. For example, air doctor coater, blade coater, rod coater, knife coater, squeeze coater, impregnation coater, reverse roller coater, transfer roller coater, curtain coater, double roller coater, slide hopper coater, gravure coater, kiss roll coater, bead coater, Examples include cast coaters, spray coaters, calendar coaters, and extrusion coaters.

  Drying of the water mixture of the aqueous compound and the white pigment applied on the medium may be performed by any method as long as water can be evaporated. For example, heating from a heat source, a heating method using infrared light, a heating method using electromagnetic induction, and the like can be given. Further, water evaporation may be performed under reduced pressure.

  Porous as used in the present invention refers to the formation of a porous white scattering material by applying a water admixture of the water-based compound and the white pigment onto the electrode and drying it, and then the silver or silver is chemically treated on the scattering material. After supplying an electrolyte solution containing the compound contained in the structure, it can be sandwiched between opposing electrodes, giving a potential difference between the opposing electrodes, causing a silver dissolution precipitation reaction, and penetrating ions that can move between the electrodes Tell the state.

  In the display element of the present invention, it is desirable to carry out a curing reaction of the water-based compound with a hardener during or after applying and drying the water mixture described above.

  Examples of the hardener used in the present invention include, for example, U.S. Pat. No. 4,678,739, column 41, 4,791,042, JP-A-59-116655, and 62-245261. No. 61-18942, 61-249054, 61-245153, JP-A-4-218044, and the like. More specifically, aldehyde hardeners (formaldehyde, etc.), aziridine hardeners, epoxy hardeners, vinyl sulfone hardeners (N, N'-ethylene-bis (vinylsulfonylacetamide) Ethane, etc.), N-methylol hardeners (dimethylolurea, etc.), boric acid, metaboric acid or polymer hardeners (compounds described in JP-A-62-234157). When gelatin is used as the aqueous compound, it is preferable to use a vinyl sulfone type hardener or a chlorotriazine type hardener alone or in combination. Moreover, when using polyvinyl alcohol, it is preferable to use boron-containing compounds such as boric acid and metaboric acid.

  These hardeners are used in an amount of 0.001 to 1 g, preferably 0.005 to 0.5 g, per 1 g of the aqueous compound. In addition, it is possible to perform heat treatment and humidity adjustment during the curing reaction in order to increase the film strength.

[Thickener added with electrolyte]
In the display element of the present invention, a thickener can be used for the electrolyte. For example, gelatin, gum arabic, poly (vinyl alcohol), hydroxyethyl cellulose, hydroxypropyl cellulose, cellulose acetate, cellulose acetate butyrate, poly ( Vinylpyrrolidone), poly (alkylene glycol), casein, starch, poly (acrylic acid), poly (methyl methacrylic acid), poly (vinyl chloride), poly (methacrylic acid), copoly (styrene-maleic anhydride), copoly ( Styrene-acrylonitrile), copoly (styrene-butadiene), poly (vinyl acetal) s (eg, poly (vinyl formal) and poly (vinyl butyral)), poly (esters), poly (urethanes), phenoxy resins, poly (PVC Redene), poly (epoxide) s, poly (carbonates), poly (vinyl acetate), cellulose esters, poly (amides), hydrophobic transparent binders such as polyvinyl butyral, cellulose acetate, cellulose acetate butyrate, polyester, Examples include polycarbonate, polyacrylic acid, polyurethane and the like.

  These thickeners may be used in combination of two or more. Moreover, the compound as described in pages 71-75 of Unexamined-Japanese-Patent No. 64-13546 can be mentioned. Among these, the compounds preferably used are polyvinyl alcohols, polyvinyl pyrrolidones, hydroxypropyl celluloses, and polyalkylene glycols from the viewpoint of compatibility with various additives and improvement in dispersion stability of white particles.

[Silver salt compound]
The electrolyte according to the present invention may contain a silver salt compound as necessary. The silver salt compound according to the present invention is silver or a compound containing silver in the chemical structure, such as silver oxide, silver sulfide, metallic silver, silver colloidal particles, silver halide, silver complex compound, silver ion and the like. There are no particular restrictions on the phase state species such as the solid state, the solubilized state in liquid, and the gas state, and the charged state species such as neutral, anionic, and cationic. When the silver salt compound according to the present invention undergoes dissolution and precipitation reaction on the electrode, black display with high contrast becomes possible.

  In the display element of the present invention, silver iodide, silver chloride, silver bromide, silver oxide, silver sulfide, silver citrate, silver acetate, silver behenate, silver p-toluenesulfonate, silver trifluoromethanesulfonate, mercapto A known silver salt compound such as a silver salt with an acid or a silver complex with iminodiacetic acid can be used. Among these, it is preferable to use, as a silver salt, a compound that does not have a nitrogen atom having coordination properties with halogen, carboxylic acid, or silver, and for example, silver p-toluenesulfonate is preferable.

  The metal ion concentration contained in the electrolyte layer according to the present invention is preferably 0.2 mol / kg ≦ [Metal] ≦ 2.0 mol / kg. If the metal ion concentration is 0.2 mol / kg or more, a silver solution having a sufficient concentration can be obtained, and a desired driving speed can be obtained. If the metal ion concentration is 2 mol / kg or less, precipitation is prevented, and storage at low temperature is possible. The stability of the electrolyte solution is improved.

[Others]
Examples of the constituent layers of the display element of the present invention include auxiliary layers such as a protective layer, a filter layer, an antihalation layer, a crossover light cut layer, and a backing layer. Sensitizer, noble metal sensitizer, photosensitive dye, supersensitizer, coupler, high boiling point solvent, antifoggant, stabilizer, development inhibitor, bleach accelerator, fixing accelerator, color mixing inhibitor, formalin scavenger, Toning agents, hardeners, surfactants, thickeners, plasticizers, slip agents, UV absorbers, anti-irradiation dyes, filter light absorbing dyes, anti-bacterial agents, polymer latex, heavy metals, antistatic agents, matting agents Etc. can be contained as required.

  These additives mentioned above are more specifically described in Research Disclosure (hereinafter abbreviated as RD), Volume 176 Item / 17643 (December 1978), Volume 184, Item / 18431 (August 1979), 187. Volume Item / 18716 (November 1979) and Volume 308 Item / 308119 (December 1989).

  Table 1 below shows the types of compounds and the locations described in these three research disclosures.

〔substrate〕
The substrate that can be used in the present invention is preferably a transparent substrate. Examples of such a transparent substrate include polyester (for example, polyethylene terephthalate), polyimide, polymethyl methacrylate, polystyrene, polypropylene, polyethylene, and polyamide. Nylon, polyvinyl chloride, polyvinylidene chloride, polycarbonate, polyether sulfone, silicon resin, polyacetal resin, fluororesin, cellulose derivative, polyolefin and other polymer films, plate substrates, glass substrates, and the like are preferably used. The transparent substrate used in the present invention refers to a substrate having a transmittance for visible light of at least 50%.

  Further, as the counter substrate, for example, an opaque substrate such as an inorganic substrate such as a metal substrate or a ceramic substrate can be used.

〔electrode〕
(Display side transparent electrode)
Of the counter electrodes, the electrode positioned on the display side is preferably a transparent electrode.

  The transparent electrode is not particularly limited as long as it is transparent and conducts electricity. For example, Indium Tin Oxide (ITO: Indium Tin Oxide), Indium Zinc Oxide (IZO: Indium Zinc Oxide), Fluorine Doped Tin Oxide (FTO), Indium Oxide, Zinc Oxide, Platinum, Gold, Silver, Rhodium, Copper, Examples thereof include chromium, carbon, aluminum, silicon, amorphous silicon, and BSO (Bismuth Silicon Oxide).

  In addition, polythiophene, polypyrrole, polyaniline, polyacetylene, polyparaphenylene, polyselenophenylene, etc., and their modifying compounds can be used alone or in combination.

  The surface resistance value is preferably 100Ω / □ or less, and more preferably 10Ω / □ or less. The thickness of the transparent electrode is not particularly limited, but is generally 0.1 to 20 μm.

(Transparent porous electrode)
As one embodiment of the transparent electrode, a nanoporous electrode having a nanoporous structure can be provided on the transparent electrode. This nanoporous electrode is substantially transparent when a display element is formed, and can carry an electroactive substance or the like.

  The nanoporous structure as used in the present invention refers to a state in which an infinite number of nanometer-sized pores exist in a layer and ionic species contained in the electrolyte can move within the nanoporous structure.

  As a method for forming such a nanoporous electrode, a dispersion containing fine particles constituting the nanoporous electrode is formed in layers by an ink jet method, a screen printing method, a blade coating method, etc., and then heated at a predetermined temperature. A method of making porous by drying, baking, a method of making nanoporous by anodizing or photoelectrochemical etching after forming an electrode layer by sputtering, CVD, atmospheric pressure plasma, etc. Is mentioned. Also, the sol-gel method, Adv. Mater. It can also be formed by the method described in 2006, 18, 2980-2983.

The main components of the fine particles constituting the nanoporous electrode are metals such as Cu, Al, Pt, Ag, Pd and Au, metal oxides such as ITO, SnO ₂ , TiO ₂ and ZnO, carbon nanotubes, glassy carbon, and diamond. It can be selected from carbon electrodes such as like carbon and nitrogen-containing carbon, and is preferably selected from metal oxides such as ITO, SnO ₂ , TiO ₂ , and ZnO.

  In order for the nanoporous electrode to have transparency, it is preferable to use fine particles having an average particle diameter of about 5 nm to 10 μm. As the shape of the fine particles, those having an arbitrary shape such as an indefinite shape, a needle shape, and a spherical shape can be used.

  The film thickness of the nanoporous electrode is preferably in the range of 0.1 to 10 μm, more preferably in the range of 0.25 to 5 μm.

[Other components of the display element]
In the display element of the present invention, a sealant, a columnar structure, and spacer particles can be used as necessary.

  Sealing agent is for sealing so that it does not leak outside and is also called sealing agent. Epoxy resin, urethane resin, acrylic resin, vinyl acetate resin, ene-thiol resin, silicon resin, modified resin A curing type such as a polymer resin, such as a thermosetting type, a photocurable type, a moisture curable type, and an anaerobic curable type can be used.

  The columnar structure provides strong self-holding (strength) between the substrates, for example, a columnar body, a quadrangular columnar body, an elliptical columnar body, a trapezoidal array arranged in a predetermined pattern such as a lattice arrangement. A columnar structure such as a columnar body can be given. Alternatively, stripes arranged at predetermined intervals may be used. This columnar structure is not a random array, but can be properly maintained at intervals of the substrate, such as an evenly spaced array, an array in which the interval gradually changes, and an array in which a predetermined arrangement pattern is repeated at a constant period. The arrangement is preferably considered so as not to disturb the display. If the ratio of the area occupied by the columnar structure in the display area of the display element is 1 to 40%, a practically sufficient strength as a display element can be obtained.

  A spacer may be provided between the pair of substrates for uniformly maintaining a gap between the substrates. Examples of the spacer include a sphere made of resin or inorganic oxide. Further, a fixed spacer having a surface coated with a thermoplastic resin is also preferably used. In order to hold the gap between the substrates uniformly, only the columnar structure may be provided, but both the spacer and the columnar structure may be provided, or instead of the columnar structure, only the spacer is used as the space holding member. May be used. The diameter of the spacer is equal to or less than the height of the columnar structure, preferably equal to the height. When the columnar structure is not formed, the diameter of the spacer corresponds to the thickness of the cell gap.

[Display element driving method]
The driving operation of the display element of the present invention may be simple matrix driving or active matrix driving. The simple matrix driving in the present invention is a driving method in which a current is sequentially applied to a circuit in which a positive line including a plurality of positive electrodes and a negative electrode line including a plurality of negative electrodes are opposed to each other in a vertical direction. Say that. By using simple matrix driving, there is an advantage that the circuit configuration and driving IC can be simplified and manufactured at low cost. The active matrix drive is a system in which scanning lines, data lines, and current supply lines are formed in a grid pattern, and are driven by TFT circuits provided in each grid pattern. Since switching can be performed for each pixel, there are merits such as gradation and memory function. For example, a circuit described in FIG. 5 of JP-A-2004-29327 can be used.

[Product application]
The display element of the present invention can be used in an electronic book field, an ID card field, a public field, a traffic field, a broadcast field, a payment field, a distribution logistics field, and the like. Specifically, keys for doors, student ID cards, employee ID cards, various membership cards, convenience store cards, department store cards, vending machine cards, gas station cards, subway and railway cards, bus cards, Cash cards, credit cards, highway cards, driver's licenses, hospital examination cards, electronic medical records, health insurance cards, Basic Resident Registers, passports, electronic books, etc.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "part by mass" or "mass%" is represented.

Example 1
<< Production of display element >>
(Preparation of electrolyte)
(Preparation of electrolyte 1)
Electrolyte solution 1 was obtained by dissolving 0.1 g of bis (trifluoromethylsulfonyl) imide lithium in 2.5 g of dimethyl sulfoxide.

(Preparation of electrolyte 2)
In 2.5 g of dimethyl sulfoxide, 3 mg of ferrocene and 0.1 g of bis (trifluoromethylsulfonyl) imide lithium were dissolved to obtain an electrolytic solution 2.

(Preparation of electrolyte 3)
10 mg of compound (1) -57 and 0.1 g of bis (trifluoromethylsulfonyl) imide lithium were dissolved in 2.5 g of dimethyl sulfoxide to obtain an electrolytic solution 3.

(Preparation of electrolyte 4)
In 2.5 g of compound S1-4, 10 mg of compound (1) -57 and 0.1 g of bis (trifluoromethylsulfonyl) imide lithium were dissolved to obtain electrolytic solution 4.

(Preparation of electrolyte 5)
In 2.5 g of Compound S1-4, 10 mg of Compound (1) -5 and 0.1 g of bis (trifluoromethylsulfonyl) imide lithium were dissolved to obtain an electrolytic solution 5.

(Preparation of electrolyte 6)
In 2.5 g of compound S1-4, 10 mg of compound (1) -30 and 0.1 g of bis (trifluoromethylsulfonyl) imide lithium were dissolved to obtain an electrolytic solution 6.

(Preparation of electrolyte solution 7)
In 2.5 g of compound S1-4, 10 mg of compound (1) -54 and 0.1 g of bis (trifluoromethylsulfonyl) imide lithium were dissolved to obtain an electrolyte solution 7.

(Preparation of electrolyte 8)
In 2.5 g of compound S1-4, 10 mg of compound (1) -2 and 0.1 g of bis (trifluoromethylsulfonyl) imide lithium were dissolved to obtain an electrolytic solution 8.

(Preparation of electrolyte 9)
In 2.5 g of compound S1-4, 10 mg of compound (1) -1 and 0.1 g of bis (trifluoromethylsulfonyl) imide lithium were dissolved to obtain an electrolytic solution 9.

(Preparation of electrolyte 10)
In 2.5 g of compound S1-4, 3 mg of titanocene, 10 mg of compound (1) -1 and 0.1 g of bis (trifluoromethylsulfonyl) imide lithium were dissolved to obtain an electrolytic solution 10.

(Preparation of electrolyte solution 11)
In 2.5 g of compound S1-4, 3 mg of ferrocene, 10 mg of compound (1) -1 and 0.1 g of bis (trifluoromethylsulfonyl) imide lithium were dissolved to obtain an electrolyte solution 11.

(Preparation of electrolyte solution 12)
In 2.5 g of compound S1-4, 3 mg of dimethylferrocene, 10 mg of compound (1) -1 and 0.1 g of bis (trifluoromethylsulfonyl) imide lithium were dissolved to obtain an electrolytic solution 12.

(Preparation of electrolytic solution 13)
In 2.5 g of Compound S1-4, 3 mg of Compound F-20, 10 mg of Compound (1) -1 and 0.1 g of bis (trifluoromethylsulfonyl) imide lithium are dissolved to obtain an electrolytic solution 13. It was.

(Preparation of electrolytic solution 14)
In 2.5 g of compound S1-4, 3 mg of compound F-19, 10 mg of compound (1) -1 and 0.1 g of bis (trifluoromethylsulfonyl) imide lithium are dissolved to obtain an electrolytic solution 14. It was.

(Preparation of electrolytic solution 15)
In 2.5 g of compound S1-4, 3 mg of compound F-1, 10 mg of compound (1) -1 and 0.1 g of bis (trifluoromethylsulfonyl) imide lithium are dissolved to obtain an electrolyte solution 15. It was.

(Preparation of electrolytic solution 16)
In 2.5 g of compound S1-4, 1.5 mg of ferrocene, 1.5 mg of compound F-1, 10 mg of compound (1) -1 and 0.1 g of bis (trifluoromethylsulfonyl) imide lithium are dissolved. Thus, an electrolytic solution 16 was obtained.

[Preparation of ink liquid]
(Preparation of ink liquid 1)
Compound Ot1 was dissolved in acetonitrile / ethanol to 3 mmol / L to prepare ink liquid 1.

(Preparation of ink liquid 2)
Compound V17 was dissolved in acetonitrile / ethanol to 3 mmol / L to prepare ink liquid 2.

(Preparation of ink liquid 3)
EC1 was dissolved in acetonitrile / ethanol so as to be 3 mmol / L to prepare ink liquid 3.

(Preparation of ink liquid 4)
Compound L1 was dissolved in acetonitrile / ethanol to 3 mmol / L to prepare ink liquid 4.

(Preparation of ink liquid 5)
Compound V5 was dissolved in acetonitrile / ethanol so as to be 3 mmol / L to prepare ink liquid 5.

(Preparation of ink liquid 6)
Compound Ot2 was dissolved in acetonitrile / ethanol to 3 mmol / L to prepare ink liquid 6.

(Preparation of ink liquid 7)
Ink liquid 7 was prepared by dissolving EC2 in acetonitrile / ethanol to 3 mmol / L.

(Preparation of ink liquid 8)
Compound L25 was dissolved in acetonitrile / ethanol to 3 mmol / L to prepare ink liquid 8.

(Preparation of ink liquid 9)
Compound L53 was dissolved in acetonitrile / ethanol to 3 mmol / L to prepare ink liquid 9.

[Production of electrodes]
(Production of electrode 1)
An ITO (Indium Tin Oxide) film having a thickness of 150 nm was formed on a 2 cm × 4 cm glass substrate having a thickness of 1.5 mm according to a known method to obtain a transparent electrode (electrode 1).

(Preparation of electrode 2)
On the produced electrode 1, a titanium dioxide film having a thickness of 2 μm (about 4 to 10 particles having an average particle diameter of 17 nm was necked) was formed by a spin coating method to obtain an electrode 2.

(Preparation of electrode 3)
Using a known method, a nickel electrode having an electrode thickness of 0.1 μm is formed on a glass substrate having a thickness of 1.5 mm and 2 cm × 4 cm, and the obtained electrode is further immersed in a displacement gold plating bath. A gold-nickel electrode (electrode 3) having a depth of 0.05 μm replaced with gold was obtained.

(Preparation of titanium dioxide dispersion)
Kuraray Poval PVA235 (manufactured by Kuraray Co., Ltd., polyvinyl alcohol resin) was added to the water / ethanol mixed solution so as to have a solid content concentration of 2% by mass, dissolved by heating, and then titanium dioxide CR-90 made by Ishihara Sangyo Co., Ltd. Was dispersed with an ultrasonic disperser so as to be 20% by mass to obtain a titanium dioxide dispersion.

(Preparation of electrode 4)
On the electrode 3 produced above, the titanium dioxide dispersion was screen-printed so that the average film thickness after drying was 20 μm, then dried at 50 ° C. for 30 minutes to evaporate the solvent, and then in an atmosphere at 85 ° C. The electrode 4 which dried for 1 hour and formed the porous white scattering layer was produced.

(Preparation of electrode 5)
After immersing the prepared electrode 2 in the ink liquid 1 prepared above at room temperature overnight, the electrode 2 is taken out, washed with ethanol, then dried at 80 ° C. for 5 minutes to evaporate the solvent, and the compound Ot1 is fixed. An electrode 5 was prepared.

(Preparation of electrode 6)
After immersing the prepared electrode 2 in the ink liquid 2 prepared above at room temperature overnight, the electrode 2 is taken out, washed with ethanol, then dried at 80 ° C. for 5 minutes to evaporate the solvent, and the compound V17 is fixed. An electrode 6 was prepared.

(Preparation of electrode 7)
After immersing the prepared electrode 2 in the ink liquid 3 prepared above at room temperature overnight, the electrode 2 was taken out, washed with ethanol, then dried at 80 ° C. for 5 minutes to evaporate the solvent, and EC1 was fixed. An electrode 7 was produced.

(Preparation of electrode 8)
After immersing the prepared electrode 2 in the ink liquid 4 prepared above at room temperature overnight, the electrode 2 is taken out, washed with ethanol, then dried at 80 ° C. for 5 minutes to evaporate the solvent, and the compound L1 is fixed. An electrode 8 was prepared.

(Preparation of electrode 9)
After immersing the prepared electrode 2 in the ink liquid 5 prepared above at room temperature overnight, the electrode 2 is taken out and washed with ethanol, and then dried at 80 ° C. for 5 minutes to evaporate the solvent and fix the compound V5. An electrode 9 was prepared.

(Production of electrode 10)
After immersing the prepared electrode 2 in the ink liquid 6 prepared above at room temperature overnight, the electrode 2 is taken out, washed with ethanol, then dried at 80 ° C. for 5 minutes to evaporate the solvent, and the compound Ot3 is fixed. An electrode 10 was prepared.

(Preparation of electrode 11)
After immersing the prepared electrode 2 in the ink liquid 7 prepared above at room temperature overnight, the electrode 2 was taken out, washed with ethanol, then dried at 80 ° C. for 5 minutes to evaporate the solvent, and EC2 was fixed. An electrode 11 was produced.

(Preparation of electrode 12)
After immersing the prepared electrode 2 in the ink liquid 8 prepared above at room temperature overnight, the electrode 2 is taken out, washed with ethanol, then dried at 80 ° C. for 5 minutes to evaporate the solvent, and the compound L25 is fixed. An electrode 12 was prepared.

(Preparation of electrode 13)
After immersing the prepared electrode 2 in the ink liquid 9 prepared above at room temperature overnight, the electrode 2 is taken out, washed with ethanol, then dried at 80 ° C. for 5 minutes to evaporate the solvent, and the compound L25 is fixed. An electrode 13 was prepared.

[Production of display element]
(Preparation of display element 1)
The periphery of the electrode 4 is bordered with an olefin-based sealant containing glass spherical beads having an average particle diameter of 40 μm as a volume fraction of 10%, and then the electrodes 4 and 5 are bonded so that the electrodes are orthogonal to each other. These were further heated and pressed to produce an empty cell. The electrolytic solution 1 was vacuum-injected into the empty cell, and the injection port was sealed with an epoxy-based ultraviolet curable resin to produce a display element 1.

(Preparation of display elements 2-31)
Display elements 2 to 31 were produced in the same manner as the display element 1 except that the observation side electrode and the electrolyte layer described in Table 1 were changed.

<< Evaluation of Display Elements 1, 2, 5-9, 25-31 >>
[Evaluation of drive stability]
Connect both electrodes of the manufactured display element to both terminals of the constant voltage power supply, apply a voltage of -1.2 V to the display electrode side of each display element for 3 seconds, and then apply a voltage of +1.2 V for 1.5 seconds. The reflectance at the maximum absorption wavelength when colored and displayed was measured with a spectrocolorimeter CM-3700d manufactured by Konica Minolta Sensing. Under the same driving conditions, driving was performed 10 times in total, and the average value of the obtained reflectances was defined as R _ave1 . Further, after driving repeatedly 10,000 times, R _ave2 was obtained by the same method. ΔR _10,000 = | R _ave1 −R _ave2 | was used as an index of the stability of reflectance when ΔR _10,000 was repeatedly driven.

<< Evaluation of Display Elements 3, 4, 10-24 >>
[Evaluation of drive stability]
Connect both electrodes of the display element to both terminals of the constant voltage power supply, apply + 1.2V voltage to the display electrode side of each display element for 3 seconds, and then apply -1.2V voltage for 1.5 seconds. The reflectance at the maximum absorption wavelength when colored and displayed was measured with a spectrocolorimeter CM-3700d manufactured by Konica Minolta Sensing. Under the same driving conditions, driving was performed 10 times in total, and the average value of the obtained reflectances was defined as R _ave1 . Further, after driving repeatedly 10,000 times, R _ave2 was obtained by the same method. ΔR _10,000 = | R _ave1 −R _ave2 | was used as an index of the stability of reflectance when ΔR _10,000 was repeatedly driven.

  Table 2 shows the configuration and evaluation results of each display element obtained as described above.

  As shown in Table 2, it can be seen that the display element using the electrolyte containing the compound represented by the general formula (1) according to the present invention is excellent in driving stability. Further, it was confirmed that the display element containing a silver salt compound in the electrolytic solution had the same effect as in Example 1.

Claims (6)

A display element comprising an electrochromic compound and an electrolyte between at least a pair of opposing electrodes, wherein the electrolyte contains a compound represented by the following general formula (1).

(In the formula, X represents a sulfur atom or an oxygen atom, and at least one X in the compound is a sulfur atom. N and m are each an integer of 1 to 10, and a is an integer of 1 to 50. R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ each represents a substituent that does not have a dissociable proton, one of which includes a carbonyl group. Or may be linked to each other to form a cyclic structure. [] Represents a repeating unit, and when it is repeated, the atoms represented by X may be different from each other. In that case, R ₁ and R ₂ may also be different from each other, and the integer represented by m may also be different.)   The display element according to claim 1, wherein n and m in the compound represented by the general formula (1) are 2 or 3, respectively.   The display element according to claim 1 or 2, wherein a in the compound represented by the general formula (1) is 2 or 3.   The display element according to claim 1, wherein the electrolyte contains a metallocene compound. The display element according to any one of claims 1 to 4, wherein the electrolyte contains a compound represented by the following general formula (F).

(Wherein R _{f1 to} R _f4 each represent hydrogen, a linear or branched alkyl group, a phenyl group, a benzyl group, an alkoxy group, or an alkylthio group, and each group may further have a substituent. R _f1 and R _f2 , R _f3 and R _f4 may form a ring, and Y ₁ and Y ₂ are S or Se, respectively. The display element according to any one of claims 1 to 5, wherein the electrochromic compound is represented by the following general formula (L).

(In the formula, Rl ₁ represents a substituted or unsubstituted aryl group, Rl ₂ and Rl ₃ each represent a hydrogen atom or a substituent. Xl represents> N-Rl ₄ , an oxygen atom or a sulfur atom, and Rl ₄ Represents a hydrogen atom or a substituent.)