JP2010217692A - Display element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a long-life display element that can be driven with a low voltage, has a fast rewriting speed, and has less corrosion of an electrode even when repeatedly used. <P>SOLUTION: The display element has an electrolyte layer containing a metal salt compound and a compound represented by general formula (1) of Z<SB>1</SB>-(R<SB>1</SB>)n between a pair of facing electrodes, and displays black and white colors by applying a voltage. In general formula (1), Z<SB>1</SB>represents a heterocycle, R<SB>1</SB>represents a substituent, and (n) represents an integer of 1 to 6. When (n) is equal to or larger than 2, each R<SB>1</SB>may be the same or different, and mutually bonded to form a condensed ring. However, one of the R<SB>1</SB>s represents a cyano group or a substituent having a cyano group. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electrochemical display device using a novel electrolyte layer composition.

  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, conventional liquid crystal displays and CRTs, and in recent years, light-emitting types such as organic EL displays are mainly used. However, when the electronic information is document information, it is necessary to watch the browsing means for a relatively long time, and these actions are hardly human-friendly means. In general, it has been pointed out that the disadvantages of light-emitting displays are flickering eyes, inconvenient to carry, restricted reading posture, need to focus on the static screen, and increase power consumption when reading 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 difficulty in white display because the reflectance is as low as about 40%. In addition, since the polymer dispersed liquid crystal requires a high voltage and uses a difference in refractive index between organic substances, the contrast of an obtained image is not sufficient. Further, the polymer network type liquid crystal has a problem that a high voltage is required and a complicated TFT circuit is required to improve the memory property. 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.

  As a display method for solving the drawbacks of each of the above-described methods, an electrodeposition method (hereinafter, abbreviated as “ED method”) using dissolution precipitation of a metal or a metal salt is known. The ED method can be driven at a low voltage of 3 V or less, has advantages such as a simple cell configuration, excellent black-white contrast and black quality, and various methods have been disclosed (for example, Patent Document 1). To 3).

  In addition, it is known that a mercaptoazole-based compound is used in an ED system, particularly an ED system using a silver salt compound as a metal salt compound (for example, Patent Document 4). Patent Document 4 shows that the memory property is improved by containing a mercaptoazole-based compound or a thioether-based compound, but it is still not sufficient. Further, in an ED display element, an electrode is formed of an electrolyte and an electrolyte. Although it is considered that the electrode is easily corroded because of direct contact, there is no mention of electrode corrosion prevention.

  In order to improve the durability of the ED method in this way, it is considered to be an important issue to prevent the corrosion of the electrode. However, the corrosion of the electrode is not reduced without reducing other performances such as rewriting speed and repeated driving stability. An effective technique for preventing this problem has not yet been found, and improvement has been desired.

U.S. Pat. No. 4,240,716 Japanese Patent No. 3428603 JP 2003-241227 A Japanese Patent Laid-Open No. 2005-266652

  The present invention has been made in view of the above problems and situations, and a problem to be solved is to provide a display element that can be driven at a low voltage, has a high rewrite speed, and has little electrode corrosion.

The above object of the present invention is achieved by the following configurations.
1. A display element having an electrolyte layer containing a metal salt compound and a compound represented by the following general formula (1) between a pair of opposing electrodes, and displaying an image by applying a voltage .

In the general formula (1), Z ₁ represents a heterocyclic ring. R ₁ represents a substituent, and n represents an integer of 1 to 6. When n is 2 or more, each R ₁ may be the same or different, and may be linked to each other to form a condensed ring. However, at least one of R ₁ represents a cyano group or a substituent having a cyano group.
2. In the general formula (1), R ₁ is a halogen atom, an alkyl group, an aryl group, an alkylcarbonamide group, an arylcarbonamide group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, a cyano group, an alkoxycarbonyl group, 2. The display element according to 1 above, which is an aryloxycarbonyl group, an alkylcarbonyl group, an arylcarbonyl group, an amino group, a hydroxy group, or a heterocyclic group.
3. In the general formula (1), Z ₁ is the display device according to the 1 or 2, characterized in that represents a nitrogen-containing heterocycle.
4). 4. The display device according to 3 above, wherein the compound represented by the general formula (1) is represented by the following general formula (2).

In General Formula (2), Z ₂ represents an atomic group necessary for constituting a nitrogen-containing heterocyclic ring together with C═N. R ₂ and R ₃ represent a substituent, and m represents an integer of 0 to 5. When m is 2 or more, each R ₂ may be the same or different, and may be linked to each other to form a condensed ring. However, at least one of R ₂ represents a cyano group, or at least one of R ₂ and R ₃ represents a substituent having a cyano group.
5). In the general formula (2), R ₂ and R ₃ are halogen atoms, alkyl groups, aryl groups, alkylcarbonamide groups, arylcarbonamide groups, alkoxy groups, aryloxy groups, alkylthio groups, arylthio groups, cyano groups, alkoxy groups. 5. The display device as described in 4 above, which is a carbonyl group, an aryloxycarbonyl group, an alkylcarbonyl group, an arylcarbonyl group, an amino group, a hydroxy group or a heterocyclic group.
6). 5. The display device according to 4 above, wherein the compound represented by the general formula (2) is represented by the following general formula (3).

In general formula (3), R ₄ and R ₅ represent a hydrogen atom and a substituent, and R ₆ represents a substituent. However, R ₅ represents a cyano group or at least one of R _{4 to} R ₆ represents a substituent having a cyano group.
7). In the general formula (3), R ₄ is a hydrogen atom, an alkyl group, an aryl group, an alkylcarbonyl group, an arylcarbonyl group, an amino group or a heterocyclic group, R ₅ is a hydrogen atom, a halogen atom, an alkyl group, an aryl group, Alkylcarbonamide group, arylcarbonamide group, alkoxy group, aryloxy group, alkylthio group, arylthio group, cyano group, alkoxycarbonyl group, aryloxycarbonyl group, alkylcarbonyl group, arylcarbonyl group, amino group, hydroxy group or hetero 7. The display device according to 6 above, wherein the ring group, R ₆ is a halogen atom, an alkyl group, an aryl group, an alkylcarbonyl group, an arylcarbonyl group or a heterocyclic group.
8). 8. The electrode according to any one of 1 to 7, wherein an electrode located on a display side of the pair of opposed electrodes is made of a transparent conductive oxide, and the metal salt compound is a silver salt compound. Display element.
9. 9. The display element according to any one of 1 to 8, wherein the electrolyte layer contains an auxiliary compound that can be further oxidized and reduced in addition to the metal salt compound.

  By means of the present invention, it is possible to provide a display element that is excellent in contrast retention when repeatedly driven, can be driven at a low voltage, has a high rewrite speed, and has little electrode corrosion.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail, but the present invention is not limited thereto.

  The display element of the present invention has an electrolyte layer containing a metal salt compound and a compound represented by the general formula (1) between a pair of opposed electrodes, and displays an image by applying a voltage. It is characterized by that. This feature is a technical feature common to the present invention according to claims 1 to 9.

  As an embodiment of the present invention, it is preferable that the electrode located on the display side of the pair of opposed electrodes is made of a transparent conductive oxide, and the metal salt compound is a silver salt compound. In addition to the metal salt compound, the electrolyte layer preferably contains an auxiliary compound that can be further oxidized and reduced.

  Hereinafter, the present invention, its components, and the best mode and mode for carrying out the present invention will be described in detail.

[Compound represented by general formula (1)]
The compound represented by the general formula (1) of the present invention is a compound in the same category as the “silver salt solvent” used for promoting dissolution and precipitation of metal salts (particularly silver salts) in ED display elements. . As the silver salt solvent, heterocyclic thiol compounds such as mercaptoazole are often used. Compared with these known silver salt solvents, the structural characteristics of the compound represented by the general formula (1) of the present invention are heterocyclic. This is because a cyano group was introduced into the structure. As a result of the study by the present inventors, by making the silver salt solvent a specific structure such as the above general formula (1), it is because the corrosive power of the compound itself is small or the compound adsorbs to other chemical species. Although it is unclear whether the electrode is protected from this attack, corrosion of the electrode is greatly suppressed, the stability during repeated driving is excellent, and the rewriting speed during low voltage driving is further improved.

In the general formula (1), Z ₁ represents a heterocyclic ring, which may be a 6-membered ring or a 5-membered ring, but is preferably a 5-membered ring. Further, the heterocyclic ring represented by Z ₁ is preferably a nitrogen-containing heterocyclic ring, and more preferably a nitrogen-containing aromatic heterocyclic ring. Examples of the nitrogen-containing heterocycle represented by Z ₁ include pyrazole ring, tetrazole ring, triazole ring, imidazole ring, oxadiazole ring, thiadiazole ring, indole ring, oxazole ring, benzoxazole ring, benzimidazole ring, benzo Although a thiazole ring, a benzoselenazole ring, a naphthoxazole ring, etc. are mentioned, a tetrazole ring, a triazole ring, and an imidazole ring are preferable, and a triazole ring is most preferable.

In the general formula (1), R ₁ represents a substituent, and the substituent represented by R ₁ is not particularly limited, and examples thereof include the following substituents.

  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 groups (eg, phenyl, naphthyl, etc.), alkylcarbonamide groups (eg, acetylamino, propionylamino, butyroylamino, etc.), arylcarbonamide groups (For example, benzoylamino, etc.), alkylsulfonamide groups (for example, methanesulfonylamino group, ethanesulfonylamino group, etc.), arylsulfonamide groups (for example, benzenesulfonylamino group, toluenesulfonylamino group, etc.), Lucoxy group, aryloxy group (for example, phenoxy), alkylthio group (for example, methylthio, ethylthio, butylthio, etc.), arylthio group (for example, phenylthio group, tolylthio group, etc.), alkylcarbamoyl group (for example, methylcarbamoyl, dimethylcarbamoyl, Ethylcarbamoyl, diethylcarbamoyl, dibutylcarbamoyl, piperidylcarbamoyl, morpholylcarbamoyl, etc.), arylcarbamoyl groups (eg, phenylcarbamoyl, methylphenylcarbamoyl, ethylphenylcarbamoyl, benzylphenylcarbamoyl, etc.), carbamoyl groups, alkylsulfamoyl groups ( For example, methylsulfamoyl, dimethylsulfamoyl, ethylsulfamoyl, diethylsulfamoyl, dibutylsulfamo Moyl, piperidylsulfamoyl, morpholylsulfamoyl, etc.), arylsulfamoyl groups (eg, phenylsulfamoyl, methylphenylsulfamoyl, ethylphenylsulfamoyl, benzylphenylsulfamoyl, etc.), sulfamoyl groups , Cyano group, alkylsulfonyl group (for example, methanesulfonyl group, ethanesulfonyl group, etc.), arylsulfonyl group (for example, phenylsulfonyl, 4-chlorophenylsulfonyl, p-toluenesulfonyl, etc.), alkoxycarbonyl group (for example, methoxycarbonyl, Ethoxycarbonyl, butoxycarbonyl etc.), aryloxycarbonyl group (eg phenoxycarbonyl etc.), alkylcarbonyl group (eg acetyl, propionyl, butyroyl etc.), arylcal Bonyl group (for example, benzoyl group, alkylbenzoyl group, etc.), acyloxy group (for example, acetyloxy, propionyloxy, butyroyloxy, etc.), carboxyl group, carbonyl group, sulfonyl group, amino group, hydroxy group or heterocyclic group (for example, 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, diazaindolizine ring, tetraazaindolizine ring group, etc.), preferably alkyl group, aryl group, alkylthio group, arylthio group, acyl group, alkylcarbonamide group Alkylamino group, a cyano group, more preferably an alkyl group, an alkylthio group, a cyano group. These substituents further include those having a substituent.

In the general formula (1), n represents an integer of 1 to 6, preferably n is 1 to 4, and more preferably n is 1 to 3. When n is 2 or more, each R ₁ may be the same or different, and may be linked to each other to form a condensed ring. However, at least one of R ₁ represents a cyano group or a substituent having a cyano group. The substituent having a cyano group is not particularly limited as long as it has a cyano group as a partial structure of the substituent, and examples thereof include an o-cyanophenyl group, an m-cyanophenyl group, and a p-cyanophenyl group. , Cyanomethyl group, 2-cyanoethyl group, 3-cyanopropyl group, cyanomethylthio group, 2-cyanoethylthio group, 3-cyanopropylthio group, etc., preferably o-cyanophenyl group, 2-cyanoethyl group , 3-cyanopropylthio group.

By having a cyano group, it is possible to promote dissolution and precipitation of a metal salt (particularly a silver salt), that is, an improvement in rewriting speed during low-voltage driving is achieved.
[Compound represented by formula (2)]
In the general formula (2), Z ₂ represents an atomic group necessary for constituting a nitrogen-containing heterocyclic ring together with C═N, and the nitrogen-containing heterocyclic ring may be a 6-membered ring or a 5-membered ring. A 5-membered ring is more preferable. Examples of the nitrogen-containing heterocycle represented by Z ₂ and C═N include a pyrazole ring, a tetrazole ring, a triazole ring, an imidazole ring, an oxadiazole ring, a thiadiazole ring, an indole ring, an oxazole ring, and a benzoxazole ring. Benzimidazole ring, benzothiazole ring, benzoselenazole ring, naphthoxazole ring and the like, and tetrazole ring, triazole ring and imidazole ring are preferable, and triazole ring is most preferable.

In the general formula (2), R ₂ and R ₃ represent substituents, and the substituents represented by R ₂ and R ₃ are not particularly limited, and examples thereof include the following substituents.

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 groups (eg, phenyl, naphthyl, etc.), alkylcarbonamide groups (eg, acetylamino, propionylamino, butyroylamino, etc.), arylcarbonamide groups (For example, benzoylamino, etc.), alkylsulfonamide groups (for example, methanesulfonylamino group, ethanesulfonylamino group, etc.), arylsulfonamide groups (for example, benzenesulfonylamino group, toluenesulfonylamino group, etc.), Lucoxy group, aryloxy group (for example, phenoxy), alkylthio group (for example, methylthio, ethylthio, butylthio, etc.), arylthio group (for example, phenylthio group, tolylthio group, etc.), alkylcarbamoyl group (for example, methylcarbamoyl, dimethylcarbamoyl, Ethylcarbamoyl, diethylcarbamoyl, dibutylcarbamoyl, piperidylcarbamoyl, morpholylcarbamoyl, etc.), arylcarbamoyl groups (eg, phenylcarbamoyl, methylphenylcarbamoyl, ethylphenylcarbamoyl, benzylphenylcarbamoyl, etc.), carbamoyl groups, alkylsulfamoyl groups ( For example, methylsulfamoyl, dimethylsulfamoyl, ethylsulfamoyl, diethylsulfamoyl, dibutylsulfamo Moyl, piperidylsulfamoyl, morpholylsulfamoyl, etc.), arylsulfamoyl groups (eg, phenylsulfamoyl, methylphenylsulfamoyl, ethylphenylsulfamoyl, benzylphenylsulfamoyl, etc.), sulfamoyl groups , Cyano group, alkylsulfonyl group (for example, methanesulfonyl group, ethanesulfonyl group, etc.), arylsulfonyl group (for example, phenylsulfonyl, 4-chlorophenylsulfonyl, p-toluenesulfonyl, etc.), alkoxycarbonyl group (for example, methoxycarbonyl, Ethoxycarbonyl, butoxycarbonyl etc.), aryloxycarbonyl group (eg phenoxycarbonyl etc.), alkylcarbonyl group (eg acetyl, propionyl, butyroyl etc.), arylcal Bonyl group (for example, benzoyl group, alkylbenzoyl group, etc.), acyloxy group (for example, acetyloxy, propionyloxy, butyroyloxy, etc.), carboxyl group, carbonyl group, sulfonyl group, amino group, hydroxy group or heterocyclic group (for example, 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, diazaindolizine ring, tetraazaindolizine ring group, etc.), and R ₂ is preferably an alkyl group, an aryl group, an alkylthio group, an arylthio group, an acyl group, an alkylcarbo group. A amide group, an alkylamino group, and a cyano group, and more preferably an alkyl group, an alkylthio group, and a cyano group. These substituents further include those having a substituent. R ₃ is preferably an alkyl group, an aryl group, or an acyl group, and more preferably an alkyl group. These substituents further include those having a substituent.

In the general formula (2), m represents an integer of 0 to 5, preferably m is 0 to 3, and more preferably m is 0 to 2. When m is 2 or more, each R ₂ may be the same or different, and may be linked to each other to form a condensed ring.

However, at least one of R ₂ represents a cyano group, or at least one of R ₂ and R ₃ represents a substituent having a cyano group.

The substituent having a cyano group is not particularly limited as long as it has a cyano group as a partial structure of the substituent, and examples thereof include an o-cyanophenyl group, an m-cyanophenyl group, and a p-cyanophenyl group. , Cyanomethyl group, 2-cyanoethyl group, 3-cyanopropyl group, cyanomethylthio group, 2-cyanoethylthio group, 3-cyanopropylthio group, etc., preferably o-cyanophenyl group, 2-cyanoethyl group , 3-cyanopropylthio group.
[Compound represented by formula (3)]
In the general formula (3), R ₄ and R ₅ represent a hydrogen atom and a substituent, and R ₆ represents a substituent. The substituent represented by R _{4 to} R ₆ is not particularly limited, and examples thereof include the following substituents.

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 groups (eg, phenyl, naphthyl, etc.), alkylcarbonamide groups (eg, acetylamino, propionylamino, butyroylamino, etc.), arylcarbonamide groups (For example, benzoylamino, etc.), alkylsulfonamide groups (for example, methanesulfonylamino group, ethanesulfonylamino group, etc.), arylsulfonamide groups (for example, benzenesulfonylamino group, toluenesulfonylamino group, etc.), Lucoxy group, aryloxy group (for example, phenoxy), alkylthio group (for example, methylthio, ethylthio, butylthio, etc.), arylthio group (for example, phenylthio group, tolylthio group, etc.), alkylcarbamoyl group (for example, methylcarbamoyl, dimethylcarbamoyl, Ethylcarbamoyl, diethylcarbamoyl, dibutylcarbamoyl, piperidylcarbamoyl, morpholylcarbamoyl, etc.), arylcarbamoyl groups (eg, phenylcarbamoyl, methylphenylcarbamoyl, ethylphenylcarbamoyl, benzylphenylcarbamoyl, etc.), carbamoyl groups, alkylsulfamoyl groups ( For example, methylsulfamoyl, dimethylsulfamoyl, ethylsulfamoyl, diethylsulfamoyl, dibutylsulfamo Moyl, piperidylsulfamoyl, morpholylsulfamoyl, etc.), arylsulfamoyl groups (eg, phenylsulfamoyl, methylphenylsulfamoyl, ethylphenylsulfamoyl, benzylphenylsulfamoyl, etc.), sulfamoyl groups , Cyano group, alkylsulfonyl group (for example, methanesulfonyl group, ethanesulfonyl group, etc.), arylsulfonyl group (for example, phenylsulfonyl, 4-chlorophenylsulfonyl, p-toluenesulfonyl, etc.), alkoxycarbonyl group (for example, methoxycarbonyl, Ethoxycarbonyl, butoxycarbonyl etc.), aryloxycarbonyl group (eg phenoxycarbonyl etc.), alkylcarbonyl group (eg acetyl, propionyl, butyroyl etc.), arylcal Bonyl group (for example, benzoyl group, alkylbenzoyl group, etc.), acyloxy group (for example, acetyloxy, propionyloxy, butyroyloxy, etc.), carboxyl group, carbonyl group, sulfonyl group, amino group, hydroxy group or heterocyclic group (for example, 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, diazaindolizine ring, tetraazaindolizine ring group and the like), and R ₄ is preferably a hydrogen atom, an alkyl group, an aryl group, or an acyl group. These substituents further include those having a substituent. R ₅ is preferably a hydrogen atom, a halogen atom, an alkyl group, an aryl group, an alkylthio group, an arylthio group, an acyl group, an alkylcarbonamide group, an alkylamino group, or a cyano group, and more preferably a hydrogen atom or an alkyl group. , An alkylthio group, and a cyano group. These substituents further include those having a substituent. R ₆ is preferably an alkyl group, an aryl group, an acyl group, or an alkylcarbonamide group, and more preferably an alkyl group. These substituents further include those having a substituent.

However, R ₅ represents a cyano group, or at least one of R _{4 to} R ₆ represents a substituent having a cyano group.

  The substituent having a cyano group is not particularly limited as long as it has a cyano group as a partial structure of the substituent, and examples thereof include an o-cyanophenyl group, an m-cyanophenyl group, and a p-cyanophenyl group. , Cyanomethyl group, 2-cyanoethyl group, 3-cyanopropyl group, cyanomethylthio group, 2-cyanoethylthio group, 3-cyanopropylthio group, etc., preferably o-cyanophenyl group, 2-cyanoethyl group , 3-cyanopropylthio group.

  In general, in order to cause dissolution and precipitation of a metal, it is necessary to solubilize the metal in the electrolyte, for example, a metal that causes a coordinate bond with the metal and a weak covalent bond with the metal. It is considered that a compound containing a chemical structural species that interacts with is useful. When focusing attention on silver as a metal species, it is known that a halogen atom, a mercapto group, a carboxyl group, an imino group, etc. are chemical structural species that interact with silver. In addition, a compound containing a nitrogen-containing heterocyclic ring is useful as a silver solvent, and further, a compound having a thioether group in addition to the heterocyclic ring is characterized by having little influence on the coexisting compound and high solubility in the solvent. is there. Furthermore, it is possible to suppress electrode corrosion of the ITO electrode by removing the thiol group.

  Next, although the preferable specific example of a compound represented by General formula (1) is shown, this invention is not limited to these compounds.

  The concentration of the compound represented by the general formula (1) contained in the electrolyte layer of the present invention is preferably 0.2 mol / kg to 10.0 mol / kg with respect to the soluble component in the electrolyte layer. If the concentration is 0.2 mol / kg or more, it is possible to dissolve silver at a concentration sufficient for driving, and a desired driving speed can be obtained. Moreover, if it is 10 mol / kg or less, the precipitation of the compound represented by the general formula (1) itself, and further the precipitation of the compound contained in the other electrolyte layer will be prevented, and the electrolyte layer during low-temperature storage will be prevented. Stability is improved.

<Basic structure of display element>
In the display element of the present invention, a transparent electrode such as an ITO electrode is provided on the electrode 1 which is an electrode (display side electrode) close to the display unit among at least one pair of opposed electrodes, and an electrode far from the other display side 2 is preferably provided with a conductive electrode. Between the electrode 1 and the electrode 2, it has an electrolyte layer containing the metal salt compound according to the present invention and the compound represented by the general formula (1), and the positive and negative polarities between at least one pair of facing electrodes By applying this voltage, the image can be displayed reversibly.

〔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 substrate facing the display-side 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 at least one pair of opposed electrodes, the electrode positioned on the display side (display side electrode) 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.

  Among them, as an electrode positioned on the display side (display side electrode), Indium Tin Oxide (ITO: Indium Tin Oxide), Indium Zinc Oxide (IZO: Indium Zinc Oxide), Fluorine Doped Tin Oxide (FTO), Oxidized An electrode made of a transparent conductive oxide such as indium or zinc oxide is preferable.

  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 such as an electrochromic dye.

  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.

(Counter electrode)
Of the at least one pair of opposing electrodes, the electrode positioned on the opposite side of the display side and the electrolyte solution (hereinafter referred to as the counter electrode) is not particularly limited as long as it conducts electricity. Although it is possible, it is preferably a transparent electrode.

  As the constituent material of the counter electrode, in addition to the same material as the transparent electrode, metals such as platinum, gold, silver, copper, aluminum, zinc, nickel, titanium, bismuth and their alloys, carbon, etc. have no transparency. Materials can also be used.

(Porous carbon electrode)
In the present invention, a porous carbon electrode can also be used as the counter electrode. Porous carbon electrodes that can be adsorbed and supported include graphite, non-graphitizable carbon, graphitizable carbon, composite carbon, and carbon compounds obtained by doping carbon with boron, nitrogen, phosphorus, etc. Can be mentioned. Examples of the shape of the carbon particles include mesophase microspheres and fibrous graphite. Mesophase spherules can be obtained by firing coal tar pitch or the like at 350 to 500 ° C., and further classifying these spherules and graphitizing by high-temperature firing can provide a good porous carbon electrode. In addition, fibrous graphite can be obtained from pitch-based, PAN-based, and vapor-grown fibers.

(Grid electrode: auxiliary electrode)
An auxiliary electrode can be attached to at least one of the at least one pair of opposing electrodes according to the present invention.

  The auxiliary electrode is preferably made of a material having a lower electrical resistance than the main electrode portion. For example, metals such as platinum, gold, silver, copper, aluminum, zinc, nickel, titanium, and bismuth and alloys thereof can be preferably used.

  The auxiliary electrode can be installed either between the main electrode portion and the substrate, or on the surface of the main electrode portion opposite to the substrate. In any case, it is only necessary that the auxiliary electrode is electrically connected to the main electrode portion.

  There are no particular restrictions on the arrangement pattern of the auxiliary electrodes. It can be appropriately formed according to the required performance, such as linear, mesh, or circular. When the main electrode part is divided into a plurality of parts, the divided electrode parts may be connected to each other. However, in the case where the main electrode portion is a transparent electrode provided on the substrate on the display side, the auxiliary electrode is required to be provided with a shape and frequency that do not impair the visibility of the display element.

  As a method of forming the auxiliary electrode, a known method can be used. For example, a patterning method by photolithography, a printing method, an ink jet method, electrolytic plating or electroless plating, or a method of forming a pattern by exposing and developing using a silver salt photosensitive material may be used.

  The line width and line spacing of the auxiliary electrode pattern may be arbitrary values, but the line width needs to be increased in order to increase the conductivity. On the other hand, when an auxiliary electrode is attached to the transparent electrode, from the viewpoint of visibility, the area coverage of the auxiliary electrode viewed from the display element observation side is preferably 30% or less, and more preferably 10% or less.

  Thus, from the viewpoint of transmittance and conductivity, the line width of the auxiliary electrode is preferably 1 μm or more and 100 μm or less, and the line interval is preferably 50 μm to 1000 μm.

(Method of forming electrode)
A known method can be used to form the transparent electrode and the metal auxiliary electrode. For example, a method of depositing a mask on a substrate by a sputtering method or the like, a method of patterning by a photolithography method after forming the entire surface, and the like can be given.

  Electrodes can also be formed by electrolytic plating, electroless plating, printing methods, and ink jet methods.

  After forming an electrode pattern including a catalyst layer having a monomer polymerization ability on a substrate using an inkjet method, a monomer component that is polymerized by the catalyst and becomes a conductive polymer layer after polymerization is added, It is also possible to form a metal electrode pattern by polymerizing and further performing metal plating such as silver on the conductive polymer layer, and the process is greatly reduced because no photoresist or mask pattern is used. It can be simplified.

  When the electrode material is formed by a coating method, for example, a known method such as a dipping method, a spinner method, a spray method, a roll coater method, a flexographic printing method, a screen printing method, or the like can be used.

  Among the ink jet methods, the following electrostatic ink jet method can continuously print a high-viscosity liquid with high accuracy, and is preferably used for forming the transparent electrode and the metal auxiliary electrode according to the present invention. The viscosity of the ink is preferably 30 mPa · s or more, and more preferably 100 mPa · s or more.

<Electrostatic inkjet method>
In the display element of the present invention, at least one of the transparent electrode of the composite electrode and the metal auxiliary electrode has a liquid discharge head having a nozzle with an internal diameter of 30 μm or less for discharging a charged liquid, and supplies a solution into the nozzle. It is one of the preferable embodiments that the liquid discharge device is provided with a supply unit that performs the discharge and a discharge voltage application unit that applies a discharge voltage to the solution in the nozzle. Further, it is preferable that the solution in the nozzle is formed by using a discharge device provided with a convex meniscus forming means for forming a state where the solution rises from the nozzle tip.

  In addition, it comprises operation control means for controlling application of drive voltage for driving the convex meniscus forming means and application of discharge voltage by the discharge voltage application means, and this operation control means applies application of the discharge voltage by the discharge voltage application means. It is also preferable to use a liquid ejection apparatus having a first ejection control unit that applies a driving voltage to the convex meniscus forming means when ejecting liquid droplets.

  In addition, an operation control unit that controls driving of the convex meniscus forming unit and voltage application by the discharge voltage applying unit is provided, and the operation control unit includes an operation for raising the solution by the convex meniscus forming unit, and application of the discharge voltage. A liquid discharge device having a second discharge control unit that synchronizes the liquid, and the operation control means includes a liquid level at the tip of the nozzle after the swell operation of the solution and the application of the discharge voltage. It is also a preferred form to use a liquid ejection apparatus having a liquid level stabilization control unit that performs operation control for drawing in the inside.

  By producing an electrode pattern using such an electrostatic inkjet, it is advantageous that an electrode having excellent on-demand characteristics, little waste material, and excellent dimensional accuracy can be obtained.

(Electronic insulation layer)
In the display element of the present invention, an electronic insulating layer can be provided.

  The electronic insulating layer applicable to the present invention may be a layer having both ionic conductivity and electronic insulating properties. For example, a solid electrolyte membrane in which a polymer or salt having a polar group is formed into a film, electronic insulating properties And a porous solid body having a low relative dielectric constant, such as a silicon-containing compound, and the like.

  As a method for forming a porous film, a sintering method (fusing method) (using fine pores formed between particles by partially fusing polymer fine particles or inorganic particles by adding a binder, etc.), extraction method ( After forming a constituent layer with a solvent-soluble organic substance or inorganic substance and a binder that does not dissolve in the solvent, the organic substance or inorganic substance is dissolved with the solvent to obtain pores), and the polymer is heated or degassed Known forming methods such as a foaming method in which foaming is performed, a phase change method in which a mixture of polymers is phase-separated by operating a good solvent and a poor solvent, and a radiation irradiation method in which pores are formed by radiating various types of radiation Can be used. Specifically, JP-A-10-30181, JP-A-2003-107626, JP-B-7-95403, JP-A-2635715, JP-A-2894523, JP-A-2987474, JP-A-3066426, and JP-A-3464513. No. 3,483,464, No. 3535942, No. 30622203, and the like.

(Electrolyte layer)
The electrolyte layer according to the present invention is a layer that is provided between opposing electrodes, contains an electrolyte, and allows ions to move. The electrolyte layer is characterized by containing a metal salt compound and a compound represented by the general formula (1). Besides, the supporting electrolyte, a metal salt solvent other than the general formula (1), an organic solvent, an oxidation-reduction May include components such as auxiliary compounds, white scatterers, and the like. The component may include a component that does not or hardly dissolves in an organic solvent such as a white scattering material, and a liquid soluble component that dissolves in an organic solvent such as a metal salt compound, a metal salt solvent, and a supporting electrolyte. is there.

  The components other than the general formula (1) that can be contained in the electrolyte layer will be described in detail below.

[Organic solvent]
The electrolyte layer according to the present invention may contain an organic solvent, and the organic solvent that can be used preferably has a boiling point in the range of 120 to 300 ° C., for example, propylene carbonate, ethylene carbonate, ethyl methyl. Carbonate, diethyl carbonate, dimethyl carbonate, butylene carbonate, γ-butyrolactone, sulfolane, dimethyl sulfoxide, butyronitrile, propionitrile, acetonitrile, acetylacetone, 4-methyl-2-pentanone, 2-butanol, 1-butanol, 2-propanol, 1-propanol, acetic anhydride, ethyl acetate, ethyl propionate, dimethoxyethane, diethoxyfuran, tetrahydrofuran, ethylene glycol, diethylene glycol, triethylene glycol Butyl ether, tricresyl phosphate, 2-ethylhexyl phosphate, dioctyl phthalate, and di-octyl sebacate and the like.

[Metal salt compounds]
The metal salt compound applicable to the display element of the present invention is a metal species that can be dissolved and deposited on at least one electrode on at least one pair of opposed electrodes by driving the counter electrode. As long as it contains a salt, any compound may be used. Preferred metal species are silver, bismuth, copper, nickel, iron, chromium, zinc and the like, and particularly preferred are silver and bismuth.

[Silver salt compound]
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.

  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 It is preferable to use a known silver salt compound such as a silver salt with an acid or a silver complex with iminodiacetic acid. Among these, it is more preferable to use a silver salt with a compound that does not have a nitrogen atom having a coordination property with halogen, carboxylic acid, or silver, and for example, silver p-toluenesulfonate is particularly preferable.

  The metal ion concentration contained in the liquid soluble component (including the organic solvent) of 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 layer is improved.

[Halogen ion, metal ion concentration ratio]
In the display element of the present invention, the molar concentration of halogen ions or halogen atoms contained in the electrolyte layer is [X] (mol / kg), and the molar concentration of metal ions contained in the electrolyte layer is [Metal] ( Mol / kg), it is preferable to satisfy the conditions defined by the following formula (1).

Formula (1)
0 ≦ [X] / [Metal] ≦ 0.01
The halogen atom means an iodine atom, a chlorine atom, a bromine atom, or a fluorine atom. When [X] / [Metal] is larger than 0.01, X ⁻ → X ₂ is generated during the metal redox reaction, and X ₂ easily cross-oxidizes with the deposited metal to dissolve the deposited metal. Therefore, the molar concentration of halogen atoms is preferably as low as possible relative to the molar concentration of metallic silver. In the case of adding halogen ions, the halogen species preferably have a total molar concentration of [I] <[Br] <[Cl] <[F] from the viewpoint of improving memory properties.

  The electrolyte layer composition according to the present invention may further contain the following components.

[Supporting electrolyte]
As the supporting electrolyte that can be used in the electrolyte layer composition according to the present invention, salts, acids, and alkalis that are usually used in the field of electrochemistry or the field of batteries can be used.

  There are no particular limitations on the salts, and for example, inorganic ion salts such as alkali metal salts and alkaline earth metal salts; quaternary ammonium salts; cyclic quaternary ammonium salts; quaternary phosphonium salts and the like can be used.

Specific examples of the salts include halogen ions, SCN ⁻ , ClO ₄ ⁻ , BF ₄ ⁻ , CF ₃ SO ₃ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ , (C ₂ F ₅ SO ₂ ) ₂ N ⁻ , PF _{^{6 -, AsF 6 -, CH}} 3 COO -, CH 3 (C 6 H 4) SO 3 -, and _{(C 2 F 5 SO 2)} 3 C - Li salt having a counter anion selected from, Na salt or K salt is mentioned.

Further, halogen ions, SCN ⁻ , ClO ₄ ⁻ , BF ₄ ⁻ , CF ₃ SO ₃ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ , (C ₂ F ₅ SO ₂ ) ₂ N ⁻ , PF ₆ ⁻ , AsF _{6 ^{-, CH 3 COO -, CH}} 3 (C 6 H 4) SO 3 -, and _{(C 2 F 5 SO 2)} 3 C - 4 quaternary ammonium salt having a counter anion selected from, preferably, _(CH 3) ₄ NBF ₄ , (C ₂ H ₅ ) ₄ NBF ₄ , (n-C ₄ H ₉ ) ₄ NBF ₄ , (C ₂ H ₅ ) ₄ NBr, (C ₂ H ₅ ) ₄ NClO ₄ , (n-C ₄ H ₉ ) ₄ NClO ₄ , CH ₃ (C ₂ H ₅ ) ₃ NBF ₄ , (CH ₃ ) ₂ (C ₂ H ₅ ) ₂ NBF ₄ , (CH ₃ ) ₄ NSO ₃ CF ₃ , (C ₂ H ₅ ) _{4 NSO 3 CF 3, (n} -C 4 H 9 ₄ NSO ₃ CF _3, include _{(C 4 H 8) 2 NSO} 3 (C 6 H 4) CH 3.

  Furthermore, the following salts etc. are mentioned.

Further, halogen ions, SCN ⁻ , ClO ₄ ⁻ , BF ₄ ⁻ , CF ₃ SO ₃ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ , (C ₂ F ₅ SO ₂ ) ₂ N ⁻ , PF ₆ ⁻ , AsF _{6 ^{-, CH 3 COO -, CH}} 3 (C 6 H 4) SO 3 -, and _{(C 2 F 5 SO 2)} 3 C - phosphonium salt having a counter anion selected from, _{preferably, (CH} 3) 4 PBF ₄ , (C ₂ H ₅ ) ₄ PBF ₄ , (C ₃ H ₇ ) ₄ PBF ₄ , (C ₄ H ₉ ) ₄ PBF _{4 and the} like.

  The supporting electrolyte according to the present invention is preferably a quaternary ammonium salt, particularly preferably a quaternary spiro ammonium salt.

  The amount of the supporting electrolyte used is arbitrary, but in general, the supporting electrolyte is present in the solvent as an upper limit of 20 mol / L or less, preferably 10 mol / L or less, more preferably 5 mol / L or less. The lower limit is usually 0.01 mol / L or more, preferably 0.04 mol / L or more.

[Metal salt solvent]
In the present invention, the “metal salt solvent” includes a compound represented by the general formula (1), and the compound represented by the general formula (1) is preferably used as a “silver salt solvent”. In order to achieve the object of the present invention, it is preferable to use only the compound represented by the general formula (1) as the <metal salt (especially silver salt) solvent>. A known silver salt solvent may be used in combination for the purpose of accelerating dissolution and precipitation of (especially silver salt), and the known silver salt solvent that can be used in combination is represented by the following general formula (G1) or general formula (G2). And the compounds represented.

(Compound represented by General Formula (G1) or General Formula (G2))
General Formula _{(G1): Rg 11 -S-} Rg 12
[Wherein Rg ₁₁ and Rg ₁₂ each represents a substituted or unsubstituted hydrocarbon group. These hydrocarbon groups may contain one or more nitrogen atoms, oxygen atoms, phosphorus atoms, sulfur atoms, and halogen atoms, and Rg ₁₁ and Rg ₁₂ may be linked to each other to form a cyclic structure. ]

[Wherein, M represents a hydrogen atom, a metal atom or quaternary ammonium. Z represents an atomic group necessary for constituting a nitrogen-containing heterocyclic ring. n represents an integer of 0 to 5, Rg ₂₁ represents a substituent, and when n is 2 or more, each Rg ₂₁ may be the same or different, and may be connected to each other to form a condensed ring. It may be formed. ]
In the general formula (G1), Rg ₁₁ and Rg ₁₂ each represent a substituted or unsubstituted hydrocarbon group, and these include a linear hydrocarbon group or a branched hydrocarbon group. Further, these hydrocarbon groups may contain one or more nitrogen atoms, oxygen atoms, phosphorus atoms, and sulfur atoms, and Rg ₁₁ and Rg ₁₂ may be connected to each other to take a cyclic structure.

  Examples of groups that can be substituted for the hydrocarbon group include amino groups, guanidino groups, quaternary ammonium groups, hydroxyl groups, halogen compounds, carboxylic acid groups, carboxylate groups, amide groups, sulfinic acid groups, sulfonic acid groups, and sulfates. Groups, phosphonic acid groups, phosphate groups, nitro groups, cyano groups and the like.

  Specific examples of the compound represented by General Formula (G1) that can be applied in the present invention are shown below, but the present invention is not limited to these exemplified compounds.

G1-1: CH ₃ SCH ₂ CH ₂ OH
G1-2: HOCH ₂ CH ₂ SCH ₂ CH ₂ OH
G1-3: HOCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ OH
G1-4: HOCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ OH
G1-5: HOCH ₂ CH ₂ SCH ₂ CH ₂ OCH ₂ CH ₂ OCH ₂ CH ₂ SCH ₂ CH ₂ OH
_{G1-6: HOCH 2 CH 2 OCH 2} CH 2 SCH 2 CH 2 SCH 2 CH 2 OCH 2 CH 2 OH
_{G1-7: H 3 CSCH 2 CH 2} COOH
G1-8: HOOCCH ₂ SCH ₂ COOH
G1-9: HOOCCH ₂ CH ₂ SCH ₂ CH ₂ COOH
G1-10: HOOCCH ₂ SCH ₂ CH ₂ SCH ₂ COOH
G1-11: HOOCCH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ COOH
G1-12: HOOCCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH (OH) CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ COOH
G1-13: HOOCCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH (OH) CH (OH) CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ COOH
G1-14: H ₃ CSCH ₂ CH ₂ CH ₂ NH ₂
G1-15: H ₂ NCH ₂ CH ₂ SCH ₂ CH ₂ NH ₂
G1-16: H ₂ NCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ NH _{2
G1-17: H 3 CSCH 2 CH 2} CH (NH 2) COOH
G1-18: H ₂ NCH ₂ CH ₂ OCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ OCH ₂ CH ₂ NH _{2
G1-19: H 2 NCH 2 CH 2} SCH 2 CH 2 OCH 2 CH 2 OCH 2 CH 2 SCH 2 CH 2 NH 2
G1-20: H ₂ NCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ NH ₂
G1-21: HOOC (NH ₂ ) CHCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ CH (NH ₂ ) COOH
G1-22: HOOC (NH ₂ ) CHCH ₂ SCH ₂ CH ₂ OCH ₂ CH ₂ OCH ₂ CH ₂ SCH ₂ CH (NH ₂ ) COOH
G1-23: HOOC (NH ₂ ) CHCH ₂ OCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ OCH ₂ CH (NH ₂ ) COOH
_{G1-24: H 2 N (O =} ) CCH 2 SCH 2 CH 2 OCH 2 CH 2 OCH 2 CH 2 SCH 2 C (= O) NH 2
_{G1-25: H 2 N (O =} ) CCH 2 SCH 2 CH 2 SCH 2 C (= O) NH 2
_{G1-26: H 2 NHN (O =} ) CCH 2 SCH 2 CH 2 SCH 2 C (= O) NHNH 2
_{G1-27: H 3 C (O =} ) CNHCH 2 CH 2 SCH 2 CH 2 SCH 2 CH 2 NHC (= O) CH 3
_{G1-28: H 2 NO 2 SCH 2} CH 2 SCH 2 CH 2 SCH 2 CH 2 SO 2 NH 2
_{G1-29: NaO 3 SCH 2 CH 2} CH 2 SCH 2 CH 2 SCH 2 CH 2 CH 2 SO 3 Na
G1-30: H ₃ CSO ₂ NHCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ NHO ₂ SCH ₃
G1-31: H ₂ N (NH) CSCH ₂ CH ₂ SC (NH) NH ₂ .2HBr
_{G1-32: H 2 N (NH)} CSCH 2 CH 2 OCH 2 CH 2 OCH 2 CH 2 SC (NH) NH 2 · 2HCl
_{G1-33: H 2 N (NH)} CNHCH 2 CH 2 SCH 2 CH 2 SCH 2 CH 2 NHC (NH) NH 2 · 2HBr
G1-34: [(CH ₃ ) ₃ NCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ N (CH ₃ ) ₃ ] 2 ⁺ · 2Cl ⁻

  Next, the compound represented by formula (G2) according to the present invention will be described.

In the general formula (G2), M represents a hydrogen atom or a metal atom. Z represents an atomic group necessary for constituting a nitrogen-containing heterocyclic ring. n represents an integer of 0 to 5, Rg ₂₁ represents a substituent, and when n is 2 or more, each Rg ₂₁ may be the same or different, and may be connected to each other to form a condensed ring. It may be formed.

  In the general formula (G2), examples of the metal atom represented by M include Li, Na, K, Mg, Ca, Zn, and Ag.

  Examples of the nitrogen-containing heterocycle having Z as a constituent in general formula (G2) include, for example, a tetrazole ring, a triazole ring, an imidazole ring, an oxadiazole ring, a thiadiazole ring, an indole ring, an oxazole ring, a benzoxazole ring, and a benzimidazole Ring, benzothiazole ring, benzoselenazole ring, naphthoxazole ring and the like.

In the general formula (G2), the substituent represented by Rg ₂₁ is not particularly limited, and examples thereof include the following substituents.

  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 groups (eg, phenyl, naphthyl, etc.), alkylcarbonamide groups (eg, acetylamino, propionylamino, butyroylamino, etc.), arylcarbonamide groups (For example, benzoylamino, etc.), alkylsulfonamide groups (for example, methanesulfonylamino group, ethanesulfonylamino group, etc.), arylsulfonamide groups (for example, benzenesulfonylamino group, toluenesulfonylamino group, etc.), Lucoxy group, aryloxy group (for example, phenoxy), alkylthio group (for example, methylthio, ethylthio, butylthio, etc.), arylthio group (for example, phenylthio group, tolylthio group, etc.), alkylcarbamoyl group (for example, methylcarbamoyl, dimethylcarbamoyl, Ethylcarbamoyl, diethylcarbamoyl, dibutylcarbamoyl, piperidylcarbamoyl, morpholylcarbamoyl, etc.), arylcarbamoyl groups (eg, phenylcarbamoyl, methylphenylcarbamoyl, ethylphenylcarbamoyl, benzylphenylcarbamoyl, etc.), carbamoyl groups, alkylsulfamoyl groups ( For example, methylsulfamoyl, dimethylsulfamoyl, ethylsulfamoyl, diethylsulfamoyl, dibutylsulfamo Moyl, piperidylsulfamoyl, morpholylsulfamoyl, etc.), arylsulfamoyl groups (eg, phenylsulfamoyl, methylphenylsulfamoyl, ethylphenylsulfamoyl, benzylphenylsulfamoyl, etc.), sulfamoyl groups , Cyano group, alkylsulfonyl group (for example, methanesulfonyl group, ethanesulfonyl group, etc.), arylsulfonyl group (for example, phenylsulfonyl, 4-chlorophenylsulfonyl, p-toluenesulfonyl, etc.), alkoxycarbonyl group (for example, methoxycarbonyl, Ethoxycarbonyl, butoxycarbonyl etc.), aryloxycarbonyl group (eg phenoxycarbonyl etc.), alkylcarbonyl group (eg acetyl, propionyl, butyroyl etc.), arylcal Bonyl group (for example, benzoyl group, alkylbenzoyl group, etc.), acyloxy group (for example, acetyloxy, propionyloxy, butyroyloxy, etc.), carboxyl group, carbonyl group, sulfonyl group, amino group, hydroxy group or heterocyclic group (for example, 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, diazaindolizine ring, tetraazaindolizine ring group, etc.). These substituents include those having further substituents.

  Next, although the preferable specific example of a compound represented by general formula (G2) is shown, this invention is not limited to these compounds.

  The compound represented by the above general formula (G2) can be used in combination for the purpose of adjusting the color tone of the deposited metal or promoting dissolution and precipitation of a metal salt (particularly silver salt). It is preferable to reduce the amount of use as much as possible in order to achieve the best results.

[Auxiliary compound that can be redox (promoter)]
In the display element of the present invention, an auxiliary compound (hereinafter referred to as a promoter) that can be oxidized and reduced may be added for the purpose of promoting dissolution and precipitation of a metal salt (particularly a silver salt). The promoter may be one that does not change the optical density in the visible region (400 to 700 nm) as a result of the oxidation-reduction reaction, or may be one that changes, that is, the electrochromic compound, and is immobilized on the electrode. It may be added to the electrolyte layer.

Examples of preferred promoters that can be used in the present invention include the following compounds.
1) Compounds having an N—O bond, such as N-oxyl derivatives such as TEMPO, N-hydroxyphthalimide derivatives, and hydroxamic acid derivatives.
2) A compound having an allyloxy free radical having a bulky substituent introduced at the 0-position, such as galvinoxyl.
3) Metallocene derivatives such as ferrocene.
4) A benzyl (diphenylethanedione) derivative.
5) Tetrazolium salt / formazan derivative.
6) Azine compounds such as phenazine, phenothiazine, phenoxazine, and acridine.
7) Pyridinium compounds such as viologen.

  In addition, hydrazyl free radical compounds such as benzoquinone derivatives, verdazyl, thiazyl free radical compounds, hydrazone derivatives, phenylenediamine derivatives, triallylamine derivatives, tetrathiafulvalene derivatives, tetracyanoquinodimethane derivatives, thianthrene derivatives, etc. can also be used as promoters. .

  In the display element of the present invention, promoters in the categories 1) and 3) are preferred, and ferrocene derivatives are particularly preferred.

[White scattered matter]
In the present invention, from the viewpoint of further increasing the display contrast and the white display reflectance, it is preferable to contain a white scattering material, and a porous white scattering layer may be formed and present.

  The porous white scattering layer applicable to the present invention is formed by applying and drying an aqueous mixture of a water-based polymer and a white pigment that does not substantially dissolve in the organic solvent of the electrolyte layer (hereinafter also referred to as electrolyte solvent). be able to.

  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 compounds include proteins such as gelatin and gelatin derivatives, or cellulose derivatives, natural compounds such as starch, gum arabic, dextran, pullulan, and carrageenan polysaccharides, polyvinyl alcohol, polyethylene glycol, polyvinyl pyrrolidone, and acrylamide polymers. And synthetic polymer compounds such as derivatives thereof. As gelatin derivatives, acetylated gelatin, phthalated gelatin, polyvinyl alcohol derivatives as 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 of the vinyl monomer having a (e.g., sodium methacrylate, Copolymers with ammonium acid, 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 polyvinylpyrrolidone compounds can be preferably used.

  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.

  The average molecular weight of the water-based polymer according to the present invention is preferably in the range of 10,000 to 2,000,000 and more preferably in the range of 30,000 to 500,000 on a weight average basis.

  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 white particles, 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 particles, 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 alcohol solvent, a compound having high solubility in water such as methanol, ethanol, isopropanol is preferably used, and the mixing ratio with the water / alcohol solvent is preferably in the range of 0.5 to 20 by mass ratio, More preferably, it is the range of 2-10.

[Solid electrolyte, gel electrolyte]
The electrolyte according to the present invention is not only a solution electrolyte composed of a solvent or an ionic liquid, but also a high-viscosity electrolyte or gel electrolyte (hereinafter, referred to as a solid electrolyte or a polymer compound containing substantially no solvent). Gel electrolyte) can be used.

  Examples of the solid electrolyte and gel electrolyte applicable to the present invention include a solid electrolyte described in JP-A No. 2002-341387, a polymer solid electrolyte described in JP-A No. 2002-341387, and JP-A No. 2004-20928. A solid polymer electrolyte described in JP-A No. 2004-191945, a solid polymer electrolyte described in JP-A No. 2005-338204, and a polymer described in JP-A No. 2006-323022 Examples thereof include solid electrolytes, solid electrolytes described in JP-A No. 2007-141658, solid electrolytes described in JP-A No. 2007-163865, and gel electrolytes.

[Thickener added to the electrolyte layer]
In the display element of the present invention, a thickener can be used in the electrolyte layer. For example, gelatin, gum arabic, poly (vinyl alcohol), hydroxyethyl cellulose, hydroxypropyl cellulose, cellulose acetate, cellulose acetate butyrate, poly (Vinyl pyrrolidone), 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 (chlorinated Nylidene), poly (epoxides), 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.

  In the display element of the present invention, polyethylene glycol having an average polymerization degree of 100 to 500 is preferable as the thickener, and it is preferably added in a range of 5 to 20% by mass ratio with respect to the organic solvent of the electrolyte layer. .

[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 The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. 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.

<< Production of display element >>
[Production of display electrode]
[Preparation of electrode 1]
A 300 nm-thick ITO (Indium Tin Oxide) film was formed on a 2 cm × 4 cm glass substrate having a thickness of 1.5 mm according to a sputtering method to obtain a transparent electrode (display electrode 1).

[Preparation of counter electrode]
(Preparation of electrode 2)
On the electrode prepared in the same manner as the electrode 1, the following titanium dioxide dispersion was screen-printed so that the average film thickness after drying was 20 μm, and then dried at 50 ° C. for 30 minutes to evaporate the solvent. Electrode 2 having a porous white scattering layer formed by drying in an atmosphere at 85 ° C. for 1 hour was produced.

<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 electrolyte layer composition)
(Preparation of electrolyte layer composition 1)
1.5 g of γ-butyrolactone, 0.025 g of the following paratoluenesulfonic acid spiro- (1,1 ′)-bipyrrolidinium as the supporting electrolyte, 0.1 g of silver trifluoromethanesulfonate as the metal salt compound, exemplified compound (1) — 0.26 g of 22 was dissolved to make an electrolyte layer composition 1.

(Preparation of electrolyte layer composition 2)
An electrolyte layer composition 2 was prepared in the same manner as the electrolyte layer composition 1 except that 0.004 g of ferrocene was added as a redox auxiliary compound.

(Preparation of electrolyte layer compositions 3-14)
Electrolyte layer compositions 3 to 14 were prepared in the same manner as electrolyte layer composition 2 except that exemplary compound (1) -22 in electrolyte layer composition 2 was changed to the types and amounts shown in Table 1 below. .

  The structures of the compounds used in the examples are described below.

  P-Toluenesulfonic acid spiro- (1,1 ')-bipyrrolidinium

[Production of display element]
(Preparation of display element 1)
After the periphery of the electrode 2 is edged with an olefin-based sealant containing glass spherical beads having an average particle diameter of 40 μm as a volume fraction of 10%, the striped electrodes are orthogonal to the electrodes 2 and 1 respectively. The cells were bonded together and further heated and pressed to produce an empty cell. The electrolyte layer composition 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.

(Production of display elements 2 to 14)
In the production of the display element 1, display elements 2 to 14 were produced in the same manner except that the electrolyte composition 1 was changed to the electrolyte compositions 2 to 14.
[Evaluation of display element]
[Evaluation of reflectance stability when driven repeatedly]
An operation of connecting both electrodes of the manufactured display element to both terminals of a constant voltage power source, applying a voltage of +1.5 V to the display side electrode for 1 second, and then applying a voltage of -1.5 V for 0.5 second. One cycle, the reflectance at a wavelength of 550 nm after applying +1.5 V and the reflectance at a wavelength of 550 nm after applying -1.5 V were measured with a spectral colorimeter CM-3700d manufactured by Konica Minolta Sensing. was a CR ₁ asked the contrast.
_Contrast: CR 1 = (+ 1.5V reflectance after application) / (- reflectance after 1.5V applied)
After driving a total of 100 times under the same driving conditions, CR ₁₀₀ was determined by the same method, CR ₁ and CR ₁₀₀ were compared according to the following formula, and the contrast retention rate was evaluated in five stages.

Contrast retention (%) = CR ₁₀₀ / CR ₁ × 100
A: Contrast retention is 80% or more. O: Contrast retention is 65% or more and less than 80%. Δ: Contrast retention is less than 65%. X: Contrast change cannot be observed visually.
[Evaluation of electrode corrosion]
By decomposing the display device used for the evaluation of the stability of reflectance when obtained by the repetitive driving, taking out the display electrodes, transmittance at 380nm of ITO and (T ₁₀₀₎ was measured using a spectrophotometer, The electrode corrosion rate was calculated according to the following formula using the transmittance (T ₁ ) of ITO before driving. The results are shown in Table 3. It is presumed that the ITO electrode corrodes by repeated driving and the transmittance varies, and the smaller the electrode corrosion rate calculated from the transmittance, the less the electrode corrosion and the better the stability.

Electrode corrosion rate (%) = (1−T ₁ / T ₁₀₀ ) × 100
[Evaluation of rewriting speed]
Connect both electrodes of the display element to both terminals of the constant voltage power supply, control the upper limit of the current value to 10 mA per square centimeter, and apply a constant voltage of -1.5 V to the display side electrode for 1 second. Then, the reflectance (%) at a wavelength of 550 nm when gray-displayed was measured with a spectrocolorimeter CM-3700d manufactured by Konica Minolta Sensing Co., Ltd., and the obtained value was designated as R _BK1 . Here, the smaller the value of _RBK1, the faster the rewriting speed.

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

  As is apparent from the results shown in Table 2, the display elements 1 to 12 of the present invention are superior in contrast retention when repeatedly driven by using the electrolyte composition containing the compound according to the present invention. In addition, a display element excellent in electrode corrosion resistance could be provided. Furthermore, it can be seen that the rewriting speed is high in spite of being able to drive at a voltage as low as ± 1.5V.

Claims (9)

A display element having an electrolyte layer containing a metal salt compound and a compound represented by the following general formula (1) between a pair of opposing electrodes, and displaying an image by applying a voltage .

In the general formula (1), Z ₁ represents a heterocyclic ring. R ₁ represents a substituent, and n represents an integer of 1 to 6. When n is 2 or more, each R ₁ may be the same or different, and may be linked to each other to form a condensed ring. However, at least one of R ₁ represents a cyano group or a substituent having a cyano group. In the general formula (1), R ₁ is a halogen atom, an alkyl group, an aryl group, an alkylcarbonamide group, an arylcarbonamide group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, a cyano group, an alkoxycarbonyl group, The display element according to claim 1, wherein the display element is an aryloxycarbonyl group, an alkylcarbonyl group, an arylcarbonyl group, an amino group, a hydroxy group, or a heterocyclic group. 3. The display element according to claim ₁ , wherein Z ₁ in the general formula (1) represents a nitrogen-containing heterocyclic ring. The display element according to claim 3, wherein the compound represented by the general formula (1) is represented by the following general formula (2).

In General Formula (2), Z ₂ represents an atomic group necessary for constituting a nitrogen-containing heterocyclic ring together with C═N. R ₂ and R ₃ represent a substituent, and m represents an integer of 0 to 5. When m is 2 or more, each R ₂ may be the same or different, and may be linked to each other to form a condensed ring. However, at least one of R ₂ represents a cyano group, or at least one of R ₂ and R ₃ represents a substituent having a cyano group. In the general formula (2), R ₂ and R ₃ are halogen atoms, alkyl groups, aryl groups, alkylcarbonamide groups, arylcarbonamide groups, alkoxy groups, aryloxy groups, alkylthio groups, arylthio groups, cyano groups, alkoxy groups. The display device according to claim 4, wherein the display device is a carbonyl group, an aryloxycarbonyl group, an alkylcarbonyl group, an arylcarbonyl group, an amino group, a hydroxy group, or a heterocyclic group. The display element according to claim 4, wherein the compound represented by the general formula (2) is represented by the following general formula (3).

In general formula (3), R ₄ and R ₅ represent a hydrogen atom and a substituent, and R ₆ represents a substituent. However, R ₅ represents a cyano group or at least one of R _{4 to} R ₆ represents a substituent having a cyano group. In the general formula (3), R ₄ is a hydrogen atom, an alkyl group, an aryl group, an alkylcarbonyl group, an arylcarbonyl group, an amino group or a heterocyclic group, R ₅ is a hydrogen atom, a halogen atom, an alkyl group, an aryl group, Alkylcarbonamide group, arylcarbonamide group, alkoxy group, aryloxy group, alkylthio group, arylthio group, cyano group, alkoxycarbonyl group, aryloxycarbonyl group, alkylcarbonyl group, arylcarbonyl group, amino group, hydroxy group or hetero The display device according to claim 6, wherein the ring group and R ₆ are a halogen atom, an alkyl group, an aryl group, an alkylcarbonyl group, an arylcarbonyl group, or a heterocyclic group. The electrode located on the display side among the pair of opposed electrodes is made of a transparent conductive oxide, and the metal salt compound is a silver salt compound. The display element as described. The display element according to claim 1, wherein the electrolyte layer contains an auxiliary compound that can be further oxidized and reduced in addition to the metal salt compound.