JP2011248191A - Display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multicolor display element that has a high reflectance ratio (contrast) and excellent memory property and durability, and further allows a given color to be developed with a simple control.SOLUTION: A display element comprises a plurality of display electrodes 13a, 13b, 13c provided separately between a transparent substrate 11 and a counter electrode 15. The plurality of display electrodes support electrochromic compounds 16a, 16b, 16c that develop colors different from one another, respectively. The electrochromic compounds 16a, 16b, 16c each include a chemical compound that repeats coloration and decoloration through reversible two-electron reaction.

Description

  The present invention relates to a display element, and more particularly to an electrochromic display element capable of multicolor display.

  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.

  In recent years, electronic paper has been actively developed as a display means to compensate for these drawbacks. Since electronic paper is characterized in that the display element is used like paper, characteristics different from those of conventional display elements such as a CRT and a liquid crystal display are required. For example, it is a reflective display element, has a high white reflectance and a high contrast ratio, can display a high definition, has a memory property, can be driven even at a low voltage, is thin and light, and inexpensive. It is necessary to have characteristics such as Among these, especially as characteristics for use like paper, the degree of demand for memory performance is increasing due to the white reflectance equivalent to that of paper and the increasing interest in the environment.

  So far, as a display element for electronic paper, for example, a method using a reflective liquid crystal, a method using electrophoresis, a method using toner migration, and the like have been proposed. However, any of the above methods has a low white reflectance and an inferior contrast ratio.

  Therefore, it is not easy to develop a display element having characteristics necessary for electronic paper.

  Furthermore, in order for a certain display element technology to spread in the market, whether or not the display element can perform multicolor display is a very important condition. However, in some of the display element technologies for electronic paper described above, it is very difficult to perform multicolor display while ensuring white reflectance and contrast ratio. Generally, in order to perform multicolor display Although a color filter is provided, the color filter itself absorbs light and the reflectance decreases. In addition, since the color filter divides one pixel into red (R), green (G), and blue (B), the reflectance of the display element further decreases, and accordingly, the white reflectance and the contrast ratio are reduced. This has caused problems such as a significant drop in visibility and a very poor visibility.

  On the other hand, as a promising technique for realizing a reflective display element without providing the color filter as described above, there is a method using an electrochromic phenomenon.

  Electrochromism is a phenomenon in which a reversible redox reaction occurs by applying a voltage and the color changes reversibly. An electrochromic display element is a display element that utilizes the coloring / decoloring (hereinafter referred to as color erasing) of an electrochromic compound that causes this electrochromic phenomenon. Since this electrochromic display element is a reflective display element and can be driven at a low voltage, it has been widely researched and developed from material development to device design as a leading candidate for display element technology for electronic paper applications. Has been done.

  There are some known examples of multicolor display elements using such an electrochromic display element. For example, a multicolor display element using an electrochromic compound in which fine particles of a plurality of types of electrochromic compounds are stacked. Is disclosed (for example, see Patent Document 1). This document describes an example of a multicolor display element in which a plurality of electrochromic compounds, which are polymer compounds having a plurality of functional functional groups with different voltages exhibiting color development, are laminated to form a multicolor display electrochromic compound. .

  There has been disclosed a display element in which electrochromic layers are formed in multiple layers on an electrode and multiple colors are developed using a difference in voltage value or current value necessary for the color development (see, for example, Patent Document 2). In this document, an example of a multicolor display element having a display layer formed by laminating or mixing a plurality of electrochromic compounds that develop different colors and have different threshold voltages for color development and different charge amounts necessary for color development Is described.

  In addition, an example of a multicolor display element is described in which a plurality of electrodes each having an electrochromic layer that generates different colors between a display substrate and a counter electrode are separated by an insulating film (for example, see Patent Document 3). )

  However, even when multi-color display is developed by these methods, the problem regarding the memory property still remains.

  In addition, although an example of an electrochromic display element with improved memory characteristics is described (for example, see Patent Document 4), at least five ITO electrodes must be laminated in the case of full color, and the optical structure in the element configuration There are problems such as a large loss, a decrease in white reflectance, and a deterioration in contrast ratio. Furthermore, the poor durability inherent in organic electrochromic display elements has not been sufficiently improved yet, and the white reflectance is high, the contrast ratio is excellent, and the memory characteristics and durability are multicolored. Realization of a display device has been demanded.

JP 2003-121883 A JP 2006-106669 A JP 2009-163005 A International Publication No. 2006/129424

  The present invention has been made in view of the above problems, and its object is to provide a display element with high reflectivity (contrast), good memory properties and durability, and any color with simple control. An object of the present invention is to provide a multi-color display element capable of developing a color.

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

  1. In a display element in which a plurality of display electrodes are provided separately between a transparent substrate and a counter electrode, and the plurality of display electrodes carry an electrochromic compound that emits different colors, the electrochromic compound is A display element characterized by repeating coloring and decoloring by a reversible two-electron reaction.

  2. 2. The display element according to 1, wherein the electrochromic compound has a quinoid structure by a reversible two-electron reaction.

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

(Wherein R ₁ represents an alkyl group, a cycloalkyl group, an alkenyl group, a cycloalkenyl group, an alkynyl group, a glycidyl group, an acrylate group, a methacrylate group, an aromatic group, a heterocyclic group, an alkoxy group, an aryloxy group, an alkoxy group. Carbonyl group, aryloxycarbonyl group, sulfonamido group, sulfamoyl group, urethane group, acyl group, carbamoyl group, acylamino group, sulfonyl group, sulfonamido group, amino group, halogen atom, cyano group, nitro group, sulfo group, carboxyl Represents at least one group selected from a group, a hydroxyl group, a phosphono group, and an oxamoyl group, and R ₂ and R ₃ are each a hydrogen atom, an alkyl group, a cycloalkyl group, an alkenyl group, a cycloalkenyl group, an alkynyl group, and a glycidyl group. , Acrylate group, methacrylate Group, aromatic group, heterocyclic group, alkoxy group, aryloxy group, alkoxycarbonyl group, aryloxycarbonyl group, sulfonamido group, sulfamoyl group, urethane group, acyl group, carbamoyl group, acylamino group, sulfonyl group, sulfone X represents at least one group selected from an amide group, an amino group, a halogen atom, a cyano group, a nitro group, a sulfo group, a carboxyl group, a hydroxyl group, a phosphono group, and an oxamoyl group, and X represents —NR ₄ —, —S—. , -O-, and R ₄ represents at least one group selected from a hydrogen atom, a hydrogen atom, an alkyl group, an aromatic group, a heterocyclic group, and an acyl group.
4). 4. The display element according to any one of 1 to 3, further comprising an electrochromic layer containing the electrochromic compound and a metal oxide supporting the electrochromic compound.

  5. 5. The display element according to 4 above, wherein the electrochromic compound is chemically bonded to the metal oxide through a silyl group.

  6). 6. The display element according to any one of 1 to 5, wherein at least one of the plurality of display electrodes is an ion-permeable porous electrode.

  7). 7. The display element according to any one of 1 to 6, wherein an insulating film for insulating the plurality of display electrodes from each other is provided between the plurality of display electrodes.

  8). 8. The display element according to 7, wherein the insulating film is a porous inorganic material.

  The present invention provides a display element with high reflectance (contrast), good memory and durability, and further capable of developing any color with simple control. We were able to.

It is sectional drawing which shows typically the structure of the display element which concerns on embodiment of this invention.

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

(Embodiment)
A display element according to an embodiment of the present invention will be described with reference to FIG.

  FIG. 1 is a cross-sectional view schematically showing a configuration of a display element 10 according to an embodiment of the present invention.

  However, FIG. 1 shows an example of the display element according to the embodiment of the present invention, and the display element according to the embodiment of the present invention is not limited to the configuration of FIG.

  First, the configuration of the display element 10 will be described.

  As shown in FIG. 1, a display element 10 according to an embodiment of the present invention includes a display substrate 11, a counter substrate 12 provided to face the display substrate 11, and the display substrate 11 and the counter substrate 12. The cell space is formed by being pasted through the spacer 18.

  The display substrate 11 is in contact with the first display electrode 13a formed on the display substrate 11, the first electrochromic layer 14a provided in contact with the first display electrode 13a, and the first electrochromic layer 14a. An insulating film 22a provided in contact with the insulating film 22a, a second display electrode 13b provided in contact with the insulating film 22a, a second electrochromic layer 14b provided in contact with the second display electrode 13b, and a second display electrode 13b. Insulating film 22b provided in contact with electrochromic layer 14b, third display electrode 13c provided in contact with insulating film 22b, and third electrochromic layer provided in contact with third display electrode 13c 14c. The display substrate 11 is a substrate for supporting the above laminated structure.

  The first display electrode 13a is an electrode for controlling the potential with respect to the counter electrode 15 and causing the first electrochromic layer 14a to develop color.

  The first electrochromic layer 14a includes a first electrochromic compound 16a and a metal oxide 17 that supports the first electrochromic compound 16a. The first electrochromic compound 16a is a portion that develops color by an oxidation-reduction reaction, and the metal oxide 17 is for carrying the first electrochromic compound 16a and performing color development and decoloration at high speed.

  The insulating film 22a is isolated so that the first display electrode 13a provided with the first electrochromic layer 14a and the second display electrode 13b provided with the second electrochromic layer 14b are insulated. Is to do. The first display electrode 13a and the second display electrode 13b must be insulated from each other in order to control the potential with respect to the counter electrode 15 independently. Therefore, the first display electrode 13a and the second display electrode 13b are insulated by the insulating film 22a.

  Similar to the first display electrode 13a, the second display electrode 13b is an electrode for controlling the potential with respect to the counter electrode 15 and causing the second electrochromic layer 14b to develop color.

  Similarly to the first electrochromic layer 14a, the second electrochromic layer 14b includes a second electrochromic compound 16b and a metal oxide 17 that supports the second electrochromic compound 16b. Similarly to the first electrochromic compound 16a, the second electrochromic compound 16b is a portion that develops a color by an oxidation-reduction reaction, and the metal oxide 17 carries the second electrochromic compound 16b and emits light. It is for performing color at high speed. The second electrochromic compound 16b develops a color different from that of the first electrochromic compound 16a.

  The insulating film 22b is isolated so that the second display electrode 13b provided with the second electrochromic layer 14b and the third display electrode 13c provided with the third electrochromic layer 14c are insulated. Is to do. The second display electrode 13b and the third display electrode 13c must be insulated from each other in order to control the potential with respect to the counter electrode 15 independently. Accordingly, the second display electrode 13b and the third display electrode 13c are insulated by the insulating film 22b.

  Similar to the second display electrode 13b, the third display electrode 13c is an electrode for controlling the potential with respect to the counter electrode 15 and causing the third electrochromic layer 14c to develop color.

  Similar to the first electrochromic layer 14a, the third electrochromic layer 14c includes a third electrochromic compound 16c and a metal oxide 17 that supports the third electrochromic compound 16c. Similar to the first electrochromic compound 16a, the third electrochromic compound 16c is a portion that develops a color by an oxidation-reduction reaction, and the metal oxide 17 carries the third electrochromic compound 16c and is extinguished. It is for performing color at high speed. The third electrochromic compound 16c develops a different color from the first electrochromic compound 16a and the second electrochromic compound 16b.

  The counter substrate 12 has a counter electrode 15 formed on the counter substrate 12. The counter electrode 15 controls the potential of the first display electrode 13a, the second display electrode 13b, or the third display electrode 13c with respect to the counter electrode 15, and the first electrochromic layer 14a or the second electrochromic layer 14b. Or it is an electrode for coloring the third electrochromic layer 14 c, and the counter substrate 12 is for supporting the counter electrode 15.

  The remaining space inside the cell is filled with the electrolyte 20 and the white scatterer 21.

  The electrolyte 20 moves electric charges as ions between the first display electrode 13a, the second display electrode 13b, or the third display electrode 13c, and the counter electrode 15, and the first electrochromic layer 14a or the second electrochromic layer 14a. This causes color development of the electrochromic layer 14b or the third electrochromic layer 14c.

  The white scatterer 21 is for improving the white reflectance when the electrochromic display element 10 is used as a reflective display element. The white scattering material 21 is formed by injecting an electrolyte 20 in which white pigment particles are dispersed into a cell. Alternatively, the white scatterer 21 may be formed by applying a resin in which white pigment particles are dispersed on the counter electrode 15.

  Next, the multicolor display operation of the display element 10 according to the embodiment of the present invention will be described.

  Since the display element 10 has the above-described structure, multicolor display can be easily performed. That is, since the first display electrode 13a, the second display electrode 13b, and the third display electrode 13c are provided separately through the insulating films 22a and 22b, the first display electrode 13a, the second display electrode 13b, and the third display electrode 13c are separated from each other. The potential of the display electrode 13a, the potential of the second display electrode 13b with respect to the counter electrode 15, and the potential of the third display electrode 13c with respect to the counter electrode 15 can be controlled independently. As a result, the first electrochromic layer 14a provided in contact with the first display electrode 13a, the second electrochromic layer 14b provided in contact with the second display electrode 13b, and the third display electrode The third electrochromic layer 14c provided in contact with 13c can be independently developed and decolored. Since the first electrochromic layer 14a, the second electrochromic layer 14b, and the third electrochromic layer 14c are provided on the display substrate 11 side, the first electrochromic layer 14a, Color development of only the first electrochromic layer 14a, color development of only the second electrochromic layer 14b, third electrochromic, depending on the color development / decoloration pattern of the second electrochromic layer 14b and the third electrochromic layer 14c Color development of only layer 14c, color development of both first electrochromic layer 14a and second electrochromic layer 14b, color development of both first electrochromic layer 14a and third electrochromic layer 14c, second electrochromic layer 14c Chromic layer 14b and third electrochromic Color development of both 14c, can be changed to six levels of color, it is possible multicolor display.

  For example, as the first electrochromic layer 14a, the second electrochromic layer 14b, or the third electrochromic layer 14c, three types of electrochromic layers that develop three different colors of red, green, and blue are used. Multi-color display is possible.

  In addition, since the white reflective layer 21 is provided in the cell, the white reflectance is high, and the first electrochromic layer 14a, the second electrochromic layer 14b, and the third electrochromic layer 14c are stacked. The resulting decrease in reflectance can be compensated, and multicolor display with excellent visibility is possible.

  In addition, the first electrochromic layer 14a, the second electrochromic layer 14b, and the third electrochromic layer 14c are respectively composed of the first electrochromic compound 16a, the second electrochromic compound 16b, and the third electrochromic compound. In the case of having a structure in which 16c is supported on the metal oxide 17, a multicolor display excellent in the response speed of color development and decoloration is possible. In particular, when an organic compound-based material having a low electron (or hole) mobility is used for the first electrochromic compound 16a, the second electrochromic compound 16b, or the third electrochromic compound 16c, the first display From the electrode 13a, the second display electrode 13b, or the third display electrode 13c, electrons (or holes) pass through the inside of the first electrochromic compound 16a, the second electrochromic compound 16b, or the third electrochromic compound 16c. Is not conducted, but via the metal oxide 17 having a higher electron (or hole) mobility than the first electrochromic compound 16a, the second electrochromic compound 16b, or the third electrochromic compound 16c. (Or holes) can be conducted Kill for, allows developing and erasing color at a faster rate, as a result, it is possible to multi-color display with excellent response speed.

  Furthermore, when the first electrochromic compound 16a, the second electrochromic compound 16b, and the third electrochromic compound 16c are chemically bonded to the metal oxide 17 via a silyl group, a stronger bonding state is formed. Therefore, when electrons (or holes) are repeatedly conducted through the metal oxide 17, the bond is not broken or decomposed, and the multicolor is superior in durability, reliability, and memory properties. Display is possible.

  Next, materials used for the display element 10 according to the embodiment of the present invention will be described.

  First, the material of each layer formed on the display substrate 11 and the display substrate 11 will be described.

<Board>
The material of the display substrate 11 is not particularly limited as long as it is a transparent material, but is not limited to a glass substrate, a plastic film (polyester, polyimide, polymethyl methacrylate, polystyrene, polypropylene, polyethylene, polyamide, nylon, polychlorinated). Substrates such as vinyl, polyvinylidene chloride, polycarbonate, polyether sulfone, silicon resin, polyacetal resin, fluororesin, cellulose derivative, and polyolefin) are used.

<Display electrode>
The material of the first display electrode 13a, the second display electrode 13b, and the third display electrode 13c is not particularly limited as long as it is a conductive material, but it is necessary to ensure light transmittance. Therefore, a transparent electrode made of a transparent material is used. The material of the transparent electrode is not particularly limited. For example, indium tin oxide (ITO), indium zinc oxide (IZO), fluorine-doped tin oxide (FTO), antimony-doped tin oxide (ATO), Examples thereof include indium oxide, zinc oxide, platinum, gold, silver, rhodium, copper, 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, but preferably ITO, FTO, ATO are used, most preferably Is ITO. 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.

<Ion-permeable porous electrode>
In the present invention, at least one of the plurality of display electrodes is preferably an ion permeable porous electrode, and more preferably, the display electrodes other than the first display electrode 13a are ion permeable porous electrodes. It is preferable that Since the second display electrode 13b and the third display electrode 13c are ion-permeable porous electrodes, ions in the electrolyte 20 can pass through the second display electrode 13b and the third display electrode 13c. Therefore, the movement of charges accompanying the oxidation-reduction reaction is facilitated, and multicolor display with excellent response speed of color development / decoloration is possible. As the material of the ion-permeable porous electrode, the materials mentioned as the materials of the first display electrode 13a, the second display electrode 13b, and the third display electrode 13c can be used. In order to obtain a permeable porous electrode, for example, indium tin oxide (ITO) fine particles are applied by spin coating or the like, or indium tin oxide (ITO) is applied on the porous insulating films 22a and 22b. Examples of the method include sputtering and stretching a polythiophene thin film to make it porous.

<Electrochromic compound>
Of the first electrochromic compound 16a, the second electrochromic compound 16b, or the second electrochromic compound 16c included in the first electrochromic layer 14a, the second electrochromic layer 14b, or the third electrochromic layer 14c. The material is not particularly limited as long as it is a material that repeats coloring and decoloring by a reversible two-electron reaction. However, from the viewpoint of higher memory properties, durability, and color development, a quinoid is preferably formed by a reversible two-electron reaction. It is a compound having a structure. More preferably, it is a compound represented by the general formula (1). By using a material that repeats coloring and decoloring by a reversible two-electron reaction, it is not necessary to exist in a radical state for a long time as often seen in a reversible one-electron reaction, and it is more stable and durable. A display element can be realized, and in particular, by using the compound represented by the general formula (1), a display element that is more excellent in memory property and durability and has a high color density can be realized.

<Description of compound represented by general formula (1)>
Hereinafter, the compound represented by the general formula (1) according to the present invention will be described.

In the general formula (1), specific examples of the substituent represented by R ₁ , R ₂ , R ₃ include, for example, an alkyl group (for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, a t-butyl group) , Pentyl group, hexyl group, etc.), cycloalkyl group (eg, cyclohexyl group, cyclopentyl group, etc.), alkenyl group, cycloalkenyl group, alkynyl group (eg, propargyl group, etc.), glycidyl group, acrylate group, methacrylate group, aromatic Group (for example, phenyl group, naphthyl group, anthracenyl group, etc.), heterocyclic group (for example, pyridyl group, thiazolyl group, oxazolyl group, imidazolyl group, furyl group, pyrrolyl group, pyrazinyl group, pyrimidinyl group, pyridazinyl group, selenazolyl group) Group, sliphoranyl group, piperidinyl group, pyrazolyl group, tetrazolyl group Etc.), alkoxy groups (for example, methoxy group, ethoxy group, propyloxy group, pentyloxy group, cyclopentyloxy group, hexyloxy group, cyclohexyloxy group, etc.), aryloxy groups (for example, phenoxy group, etc.), alkoxycarbonyl groups (For example, methyloxycarbonyl group, ethyloxycarbonyl group, butyloxycarbonyl group, etc.), aryloxycarbonyl group (for example, phenyloxycarbonyl group, etc.), sulfonamide group (for example, methanesulfonamide group, ethanesulfonamide group, Butanesulfonamide group, hexanesulfonamide group, cyclohexanesulfonamide group, benzenesulfonamide group, etc.), sulfamoyl group (for example, aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl) Group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl 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 group (eg acetyl group, propionyl group, butanoyl group, hexanoyl group, cyclohexanoyl group, benzoyl group, pyridinoyl group etc.), carbamoyl group (eg aminocarbonyl) Group, methylaminocarbonyl group, dimethylaminocarbonyl group, propylaminocarbonyl group, pentylaminocarbonyl group, cyclohexylaminocarbonyl group, phenylaminocarbonyl group, 2-pyridyl Minocarbonyl group etc.), acylamino group (eg acetylamino group, benzoylamino group, methylureido group etc.), amide group (eg acetamido group, propionamide group, butanamide group, hexaneamide group, benzamide group etc.), sulfonyl Group (for example, methylsulfonyl group, ethylsulfonyl group, butylsulfonyl group, cyclohexylsulfonyl group, phenylsulfonyl group, 2-pyridylsulfonyl group, etc.), sulfonamide group (for example, methylsulfonamide group, octylsulfonamide group, phenylsulfone) Amide group, naphthylsulfonamide group, etc.), amino group (eg, amino group, ethylamino group, dimethylamino group, butylamino group, cyclopentylamino group, anilino group, 2-pyridylamino group, etc.), halogen atom ( For example, 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), oxamoyl group Etc. Further, these groups may be further substituted with these groups.

R ₁ is preferably a substituted or unsubstituted aryl group, more preferably a substituted or unsubstituted phenyl group, most preferably a substituted or unsubstituted 4-aminophenyl group, 2-hydroxyphenyl group, or 4 -A hydroxyphenyl group. By having a hydroxy group at the 2-position or 4-position of the phenyl group, a quinoid structure is easily formed by a two-electron oxidation reaction, so that both excellent memory properties and color development can be achieved.

R ₂ and R ₃ are preferably an alkyl group, a cycloalkyl group, an aromatic group, or a heterocyclic group, more preferably one of R ₂ and R ₃ is a phenyl group, the other is an alkyl group, and more preferably R ₂ and R ₃ are both phenyl groups.

X is preferably> N—R ₄ . R ₄ is 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 an acyl group. It is.

  In the present invention, the compound represented by the general formula (1) may be a low molecule or a polymer as long as it contains the skeleton represented by the general formula (1).

In the present invention, the first electrochromic compound 16a, the second electrochromic compound 16b, or the second electrochromic compound 16a included in the first electrochromic layer 14a, the second electrochromic layer 14b, or the third electrochromic layer 14c. It is preferable to form the first electrochromic layer 14a, the second electrochromic layer 14b, or the third electrochromic layer 14c in which the electrochromic compound 16c is supported on the metal oxide. It is preferable that the compound is chemisorbed or physically adsorbed on the metal oxide. The chemical adsorption according to the present invention is a relatively strong adsorption state due to a chemical bond with the metal oxide surface, and the physical adsorption is a relatively weak adsorption state due to van der Waals force acting between the metal oxide surface. . In the present invention, is preferably chemisorption, as the _{chemisorption, -CO 2 H, -P = O} (OH) 2, -OP = O (OH) 2, -SO 3 H, -Si (OR ) ₃ (R represents an alkyl group), and the like are mentioned. Preferably, —CO ₂ H, —P═O (OH) ₂ , —Si (OR) _{3 and the} like are used. However, it is most preferably -Si (OR) _3, which is chemically bonded to the metal oxide via a silyl group.

  Specific examples of the compound represented by the general formula (1) are shown below, but the present invention is not limited to these exemplified compounds.

<Metal oxide>
The material of the metal oxide 17 is not particularly limited, but titanium oxide, zinc oxide, tin oxide, aluminum oxide (hereinafter referred to as alumina), zirconium oxide, cerium oxide, silicon oxide (hereinafter referred to as silica), yttrium oxide, Oxygen boron, magnesium oxide, strontium titanate, potassium titanate, barium titanate, calcium titanate, calcium oxide, ferrite, hafnium oxide, tungsten oxide, iron oxide, copper oxide, nickel oxide, cobalt oxide, barium oxide, strontium oxide Metal oxides mainly composed of vanadium oxide, aluminosilicate, calcium phosphate, aluminosilicate and the like are used. Moreover, these metal oxides may be used independently and 2 or more types may be mixed and used. In view of electrical properties such as electrical conductivity and physical properties such as optical properties, it is selected from titanium oxide, zinc oxide, tin oxide, alumina, zirconium oxide, iron oxide, magnesium oxide, indium oxide, and tungsten oxide. When one kind or a mixture thereof is used, multicolor display excellent in response speed of color development and decoloration is possible. In particular, when titanium oxide is used, multicolor display with a more excellent response speed of color development and decoloration is possible.

  Further, the shape of the metal oxide 17 is not particularly limited, but in order to efficiently carry the first electrochromic compound 16a, the second electrochromic compound 16b, or the third electrochromic compound 16c, A shape having a large surface area per unit volume (hereinafter referred to as specific surface area) is used. For example, when the metal oxide 17 is an aggregate of nanoparticles, since it has a large specific surface area, the electrochromic compound is more efficiently supported, and a multicolor display excellent in display / decolor display contrast ratio is achieved. Is possible.

<Insulating film>
The material of the insulating film 22 is not particularly limited, but a porous insulating film is preferably used. By using the porous insulating film, the electrolyte 20 can pass through the insulating film 22. Therefore, the movement of charges as ions in the electrolyte 20 accompanying the oxidation-reduction reaction is facilitated, and multicolor display excellent in the response speed of color development and decoloration is possible. More preferably, a porous inorganic insulating film containing silica, alumina or the like is used, and since a porous inorganic insulating film containing silica, alumina or the like is used, since the insulating film 22 is an inorganic material, the durability is excellent. Multi-color display is possible.

  Next, the material of the counter substrate 12 and the counter electrode 15 formed on the counter substrate 12 will be described.

<Counter substrate, counter electrode>
The material of the counter substrate 12 is not particularly limited, and an opaque substrate such as an inorganic substrate such as a metal substrate or a ceramic substrate can be used in addition to the materials described as the material of the display substrate 11.

  The material of the counter electrode 15 is not particularly limited as long as it is a conductive material. When a glass substrate or a plastic film is used as the counter substrate 12, the material of the counter electrode 15 is a transparent conductive film such as ITO, FTO, or zinc oxide, or platinum, gold, silver, copper, aluminum, zinc, nickel, titanium. , Conductive metals such as bismuth and their alloys, carbon and other non-transparent materials are also preferably used. The counter electrode 15 made of these transparent conductive film or conductive metal is used by being coated on the counter substrate 12. On the other hand, when a metal plate such as zinc is used as the counter electrode 15, the counter substrate 12 can also serve as the counter electrode 15.

In addition, a nanoporous electrode having a nanoporous structure can be provided on the counter electrode. 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. Particularly preferred is TiO ₂ .

<Counter electrode reaction layer>
The counter electrode 15 may have a layer of a compound exhibiting electrochemical activity (counter electrode reaction layer) on the counter electrode 15, and by immobilizing the counter electrode reactant on the counter electrode 15 as a counter electrode reaction layer, Since the transfer of electrons as a whole of the display element proceeds smoothly and unnecessary oxidation-reduction reactions in the display element are suppressed, the first electrochromic layer 14a, the second electrochromic layer 14b, or the second The reaction of color development / decoloration in the electrochromic layer 14c becomes more stable and faster. As a method of immobilizing the counter electrode reactant on the counter electrode 15, —CO ₂ H, —P═O (OH) ₂ , —OP═O (OH) ₂ , —SO ₃ H, —Si (OR) ₃ Examples thereof include a method in which the counter electrode 15 and the counter electrode reactant form a chemical bond via a group such as R represents an alkyl group.

<Electrolyte>
As a material for the electrolyte 20, generally, a material in which a supporting salt is dissolved in a solvent is used.

<Supporting salt>
As the supporting salt, salts, acids and alkalis 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, specifically, (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,
Furthermore,

Etc.

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, specifically, _(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. Moreover, these mixtures can also be used suitably.

  The supporting electrolyte of the present invention is preferably a quaternary ammonium salt, particularly a quaternary spiro ammonium salt and a lithium salt.

<Solvent>
The solvent 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, acetonitrile, γ-butyrolactone, sulfolane, dioxolane, tetrahydrofuran. , 2-methyltetrahydrofuran, dimethyl sulfoxide, 1,2-dimethoxyethane, 1,2-ethoxymethoxyethane, polyethylene glycol, butyronitrile, propionitrile, acetylacetone, 4-methyl-2-pentanone, 2-butanol, 1-butanol 2-propanol, 1-propanol, acetic anhydride, ethyl acetate, ethyl propionate, diethoxyfuran, ethylene glycol, diethylene glycol Call, triethylene glycol monobutyl ether, tricresyl phosphate, 2-ethylhexyl phosphate, dioctyl phthalate, dioctyl sebacate or the like is used. In addition, since it is not particularly limited to a liquid electrolyte in which a supporting salt is dissolved in a solvent, a gel electrolyte or a solid electrolyte such as a polymer electrolyte is also used.

<White scattering material>
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 scatterer, and even if formed by injecting an electrolyte 20 in which white pigment particles are dispersed in a cell. Alternatively, a resin in which white pigment particles are dispersed may be formed by applying the resin on the counter electrode 15, but it is preferable to inject an electrolyte in which white pigment particles are dispersed. Examples of the material of the white pigment particles contained in the white reflective layer 21 include titanium oxide, aluminum oxide, zinc oxide, silica, cesium oxide, yttrium oxide, barium sulfate, calcium carbonate, magnesium oxide and zinc hydroxide, magnesium hydroxide. , Magnesium phosphate, magnesium hydrogen phosphate, alkaline earth metal salt, talc, kaolin, zeolite, acidic clay, organic compounds such as polyethylene, polystyrene, acrylic resin, ionomer, ethylene-vinyl acetate copolymer resin, benzoguanamine resin, urea -Formalin resin, melamine-formalin resin, 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 particles, titanium dioxide is preferably used from the viewpoint of coloring prevention at high temperature and the reflectance of the element due to the refractive index, and particularly inorganic oxides (Al ₂ O ₃ , AlO (OH), Titanium dioxide surface-treated with SiO ₂ or the like is more preferably used.

<Thickener>
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 (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. .

<Promoter>
Further, in order to promote the electrochemical reaction of the electrochromic material, an auxiliary compound (promoter) that can be oxidized and reduced may be added. The promoter is not particularly limited and can be appropriately selected according to the purpose. A known EC compound can be used, but when used as a redox mediator, an electrochromic compound used as a display dye The known mediators described in the Journal of Synthetic Organic Chemistry, Vol. 43, No. 6 (Special Issue on “Organic Synthesis Using Electric Energy”) (1985), etc. .

<Other additives>
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).

  The types of compounds and their descriptions shown in these three research disclosures are listed below.

Additive RD17643 RD18716 RD308119
Page Classification Page Page Classification Chemical sensitizer 23 III 648 Upper right 96 III
Sensitizing dye 23 IV 648-649 996-8 IV
Desensitizing dye 23 IV 998 IV
Dye 25-26 VIII 649-650 1003 VIII
Development accelerator 29 XXI 648 Upper right Anti-fogging agent / stabilizer
24 IV 649 Upper right 1006-7 VI
Brightener 24 V 998 V
Hardener 26 X 651 Left 1004-5 X
Surfactant 26-7 XI 650 Right 1005-6 XI
Antistatic agent 27 XII 650 Right 1006-7 XIII
Plasticizer 27 XII 650 Right 1006 XII
Slipper 27 XII
Matting agent 28 XVI 650 Right 1008-9 XVI
Binder 26 XXII 1003-4 IX
Support 28 XVII 1009 XVII
As described above, according to the electrochromic display element 10 according to the present embodiment, the potential of the first display electrode 13a, the potential of the second display electrode 13b, and the potential of the third display electrode 13c are independently determined. And the first electrochromic layer 14a, the second electrochromic layer 14b, and the third electrochromic layer 14c can be independently developed and decolored by simple control, and further the reflection A multicolor display element having a high rate (contrast) and good memory property can be provided.

(Preparation of display substrate 1)
The display electrode and the electrochromic layer were produced as follows. On a glass substrate having a transparent conductive thin film of tin oxide formed on the front surface as a first display electrode, a titanium oxide nanoparticle dispersion (SP210, manufactured by Showa Titanium Co., Ltd.) and 5% by mass of Exemplified Compound (1) -61 2 , 2,3,3-tetrafluoropropanol solution mixed at a ratio of 4 / 2.4 is applied by spin coating, and annealed at 120 ° C. for 10 minutes to form the first electrochromic layer. Formed. Subsequently, an insulating film was formed by depositing ZnS / SiO ₂ having a composition ratio of 8/2 to a thickness of 100 nm by a sputtering method. Thereafter, an ITO film was formed to a thickness of 100 nm by a sputtering method to obtain a second display electrode. Next, a titanium oxide nanoparticle dispersion (SP210, manufactured by Showa Titanium Co., Ltd.) and a 5 mass% 2,2,3,3-tetrafluoropropanol solution of Exemplified Compound (1) -62 at a ratio of 4 / 2.4 The mixed coating solution was applied by a spin coating method and annealed at 120 ° C. for 10 minutes to form a second electrochromic layer. Subsequently, an insulating film was formed by depositing ZnS / SiO ₂ having a composition ratio of 8/2 to a thickness of 100 nm by a sputtering method. Thereafter, an ITO film was formed to a thickness of 100 nm by sputtering to form a third display electrode. Next, a titanium oxide nanoparticle dispersion (SP210, manufactured by Showa Titanium Co., Ltd.) and a 5 mass% 2,2,3,3-tetrafluoropropanol solution of Exemplified Compound (1) -63 at a ratio of 4 / 2.4 The mixed coating solution was applied by a spin coating method and annealed at 120 ° C. for 10 minutes to form a third electrochromic layer.

(Preparation of counter substrate 1)
A counter electrode made of tin oxide was formed on the entire surface of the counter substrate made of a glass substrate. A 20 mass% aqueous dispersion of tin oxide particles (manufactured by Mitsubishi Materials Corporation) having a primary particle size of 30 nm is formed on the upper surface of a glass substrate on which a transparent conductive thin film of tin oxide is formed on the entire surface by spin coating. It apply | coated so that it might become 2 micrometers. Then, it was made to sinter for 1 hour at 400 degreeC, and the counter substrate 1 was produced.

<Preparation of display element 1>
The display substrate 1 and the counter substrate 1 were bonded to each other through a 75 μm spacer to produce a cell. 35% by mass of titanium oxide particles (manufactured by Ishihara Sangyo Co., Ltd.) having a primary particle size of 300 nm are dispersed in a solution in which 0.025 g of tetrabutylammonium perchlorate is dissolved in 2.5 g of propylene carbonate to prepare an electrolyte solution. The display element 1 was produced by enclosing it in the inside.

(Preparation of display substrate 2)
A display substrate 2 was produced in the same manner as in the production method of the display substrate 1 except that the following compound A was used instead of the exemplified compound (1) -62.

<Preparation of display element 2>
A display element 2 was manufactured in the same manner as in the method for manufacturing the display element 1 except that the display substrate 2 was used instead of the display substrate 1.

(Preparation of display substrate 3)
In the method for producing the display substrate 1, the exemplified compound (1) -64 is substituted for the exemplified compound (1) -61, the exemplified compound (1) -65 is substituted for the exemplified compound (1) -62, and the exemplified compound ( 1) A display substrate 3 was produced in the same manner except that the exemplary compound (1) -66 was used instead of -63.

<Preparation of display element 3>
A display element 3 was manufactured in the same manner as in the manufacturing method of the display element 1 except that the display substrate 3 was used instead of the display substrate 1.

(Preparation of display substrate 4)
In the manufacturing method of the display substrate 1, a polyolefin-based porous insulating film (Hypore, Asahi Kasei E Chemicals Co., Ltd.) is used instead of the ZnS / SiO ₂ insulating film on the first electrochromic layer and the second electrochromic layer. The display substrate 4 was produced in the same manner except that the product was made by stacking.

<Preparation of display element 4>
In the production of the display element 1, the display element 4 was produced in the same manner except that the display substrate 4 was used instead of the display substrate 1.

(Preparation of display substrate 5)
In the production of the display electrode 1, a 5% by mass 2,2,3,3-tetrafluoropropanol solution of Exemplified Compound (1) -61 was spun onto a glass substrate on which a transparent conductive thin film of tin oxide was formed on the entire surface. The first electrochromic layer was formed by applying the coating method and performing an annealing treatment at 120 ° C. for 10 minutes. Subsequently, an insulating film was formed by depositing ZnS / SiO ₂ having a composition ratio of 8/2 to a thickness of 100 nm by a sputtering method. Thereafter, an ITO film was formed to a thickness of 100 nm by a sputtering method to obtain a second display electrode. Next, a 5% by mass 2,2,3,3-tetrafluoropropanol solution of Exemplified Compound (1) -62 was applied by a spin coating method, and annealed at 120 ° C. for 10 minutes, whereby the second electrochromic was performed. A layer was formed. Subsequently, an insulating film was formed by depositing ZnS / SiO ₂ having a composition ratio of 8/2 to a thickness of 100 nm by a sputtering method. Thereafter, an ITO film was formed to a thickness of 100 nm by sputtering to form a third display electrode. Next, a 5% by mass 2,2,3,3-tetrafluoropropanol solution of Exemplified Compound (1) -63 was applied by spin coating, and annealed at 120 ° C. for 10 minutes to form a third electrochromic. A layer was formed, and the display substrate 5 was produced.

(Preparation of display element 5)
A display element 5 was manufactured in the same manner as in the manufacturing method of the display element 1 except that the display substrate 5 was used instead of the display substrate 1.

(Preparation of display substrate 6)
The display electrode and the electrochromic layer were produced as follows. As a first display electrode, a titanium oxide nanoparticle dispersion (SP210, manufactured by Showa Titanium Co., Ltd.) and 5% by mass of the following compound B 2,2,3 are formed on a glass substrate having a transparent conductive thin film of tin oxide formed on the front surface. , 3-tetrafluoropropanol solution mixed at a ratio of 4 / 2.4 was applied by spin coating, and annealed at 120 ° C. for 10 minutes to form a first electrochromic layer. Subsequently, an insulating film was formed by depositing ZnS / SiO ₂ having a composition ratio of 8/2 to a thickness of 100 nm by a sputtering method. Thereafter, an ITO film was formed to a thickness of 100 nm by a sputtering method to obtain a second display electrode. Next, a coating liquid in which a titanium oxide nanoparticle dispersion (SP210, manufactured by Showa Titanium Co., Ltd.) and a 5 mass% 2,2,3,3-tetrafluoropropanol solution of the following compound C are mixed at a ratio of 4 / 2.4. Was applied by spin coating and annealed at 120 ° C. for 10 minutes to form a second electrochromic layer, thereby producing a display substrate 6.

<Preparation of display element 6>
A display element 6 was manufactured in the same manner as in the manufacturing method of the display element 1 except that the display substrate 6 was used instead of the display substrate 1.

(Color development test)
The color development / decoloration measurement of the element was performed by irradiating diffused light using a spectrocolorimeter LCD-5000 manufactured by Otsuka Electronics Co., Ltd. For voltage application, a function generator FG-02 manufactured by Toho Giken Co., Ltd. was used.

  The display elements 1 to 5 show white in the state where no voltage is applied. Next, when the first display electrode is connected to the positive electrode, the counter electrode is connected to the negative electrode, and a voltage of 2.5 V is applied, the color is yellow. . Next, when the second display electrode was connected to the positive electrode, the counter electrode was connected to the negative electrode, and a voltage of 2.5 V was applied, a magenta color was developed. Next, when the third display electrode was connected to the positive electrode, the counter electrode was connected to the negative electrode, and a voltage of 2.5 V was applied, the color was developed to cyan. Furthermore, when the first display electrode, the second display electrode, and the third display electrode were connected to the positive electrode, the counter electrode was connected to the negative electrode, and a voltage of 2.5 V was applied, the color was black.

  The display element 6 of the comparative example shows white in a state where no voltage is applied, and then, when the voltage of 2.5 V is applied with the first display electrode connected to the negative electrode and the counter electrode connected to the positive electrode, the color is blue. . Next, when the second display electrode was connected to the negative electrode, the counter electrode was connected to the positive electrode, and a voltage of 2.5 V was applied, the color was green. Next, when the third display electrode was connected to the positive electrode, the counter electrode was connected to the negative electrode, and a voltage of 2.5 V was applied, the color was developed to cyan. Further, when the counter electrode was connected to the positive electrode to the electrode that lost the first display electrode and the second display electrode and a voltage of 2.5 V was applied, the color was black.

(Evaluation of reflectance)
The reflectance at a wavelength of 550 nm in white display in a state where the voltage of the manufactured display elements 1 to 5 is not applied, the first display electrode, the second display electrode, and the third of the display elements 1 to 5 When the display electrode is connected to the positive electrode, the counter electrode is connected to the negative electrode, and a voltage of 2.5 V is applied for 1.5 seconds to display black, the reflectance at a wavelength of 550 nm is a spectral colorimeter CM manufactured by Konica Minolta Sensing Co., Ltd. It was measured at −3700d.

  On the other hand, the display element 6 connects the reflectance at a wavelength of 550 nm in white display in a state where no voltage is applied, the first display electrode and the second display electrode to the negative electrode, and the counter electrode to the positive electrode. The reflectance at a wavelength of 550 nm when a voltage of 2.5 V was applied for 1.5 seconds to display black was measured in the same manner.

(Evaluation of memory)
Next, for the display elements 1 to 6 displayed in black, the time required for the reflectivity to increase by 10% in the circuit open state was obtained, and this was used as a measure of the memory property. The longer the rise time, the better the memory.

(Durability evaluation (reflectance 5% fluctuation frequency))
The first display electrode, the second display electrode, and the third display electrode of the produced display element display elements 1 to 5 are connected to the positive electrode, the counter electrode is connected to the negative electrode, and a voltage of 2.5 V is applied for 1.5 seconds. The reflectance at a wavelength of 550 nm when displaying black, the first display electrode, the second display electrode, and the third display electrode are connected to the negative electrode, the counter electrode is connected to the positive electrode, and a voltage of 2.5 V is set to 1. The reflectance at a wavelength of 550 nm when white is displayed by applying for 5 seconds is repeatedly measured with a spectral colorimeter CM-3700d manufactured by Konica Minolta Sensing Co., Ltd., and the white reflectance or black reflectance is 5% or more. The number of times required to change was obtained and used as a measure of durability. It shows that it is excellent in durability, so that the frequency | count of fluctuation is large.

  On the other hand, the display element 6 has a wavelength of 550 nm when the first display electrode and the second display electrode are connected to the negative electrode, the counter electrode is connected to the positive electrode, and a voltage of 2.5 V is applied for 1.5 seconds to display black. Reflectance at a wavelength of 550 nm when the first display electrode and the second display electrode are connected to the positive electrode, the counter electrode is connected to the negative electrode, and a voltage of 2.5 V is applied for 1.5 seconds to display black. The rate was measured in the same way.

  That is, the display element of the present invention can easily perform multicolor display by selecting a display electrode to which a voltage is applied between the first display electrode, the second display electrode, and the third display electrode, As is apparent from the results shown in Table 1, the display elements 1 to 5 satisfying the configuration of the present invention have significantly improved memory performance as compared with the display element 6 of the comparative example, and the reflectance at the time of white display. Since the reflectivity is high and the reflectance during black display is low, it is possible to display an image with high contrast.

10 Display element 11 Display substrate (transparent substrate)
12 counter substrate 13a first display electrode 13b second display electrode 13c third display electrode 14a first electrochromic layer 14b second electrochromic layer 14c third electrochromic layer 15 counter electrode 16a first electro Chromic compound 16b Second electrochromic compound 16c Third electrochromic compound 17 Metal oxide 18 Spacer 20 Electrolyte 21 White scatterer 22a, 22b Insulating film

Claims (8)

  In a display element in which a plurality of display electrodes are provided separately between a transparent substrate and a counter electrode, and the plurality of display electrodes carry an electrochromic compound that emits different colors, the electrochromic compound is A display element characterized by repeating coloring and decoloring by a reversible two-electron reaction.   The display element according to claim 1, wherein the electrochromic compound has a quinoid structure by a reversible two-electron reaction. The display element according to claim 1, wherein the electrochromic compound is represented by the following general formula (1).

(Wherein R ₁ represents an alkyl group, a cycloalkyl group, an alkenyl group, a cycloalkenyl group, an alkynyl group, a glycidyl group, an acrylate group, a methacrylate group, an aromatic group, a heterocyclic group, an alkoxy group, an aryloxy group, an alkoxy group. Carbonyl group, aryloxycarbonyl group, sulfonamido group, sulfamoyl group, urethane group, acyl group, carbamoyl group, acylamino group, sulfonyl group, sulfonamido group, amino group, halogen atom, cyano group, nitro group, sulfo group, carboxyl Represents at least one group selected from a group, a hydroxyl group, a phosphono group, and an oxamoyl group, and R ₂ and R ₃ are each a hydrogen atom, an alkyl group, a cycloalkyl group, an alkenyl group, a cycloalkenyl group, an alkynyl group, and a glycidyl group. , Acrylate group, methacrylate Group, aromatic group, heterocyclic group, alkoxy group, aryloxy group, alkoxycarbonyl group, aryloxycarbonyl group, sulfonamido group, sulfamoyl group, urethane group, acyl group, carbamoyl group, acylamino group, sulfonyl group, sulfone X represents at least one group selected from an amide group, an amino group, a halogen atom, a cyano group, a nitro group, a sulfo group, a carboxyl group, a hydroxyl group, a phosphono group, and an oxamoyl group, and X represents —NR ₄ —, —S—. , -O-, and R ₄ represents at least one group selected from a hydrogen atom, a hydrogen atom, an alkyl group, an aromatic group, a heterocyclic group, and an acyl group.   The display element according to claim 1, further comprising an electrochromic layer containing the electrochromic compound and a metal oxide supporting the electrochromic compound.   The display element according to claim 4, wherein the electrochromic compound is chemically bonded to the metal oxide via a silyl group.   6. The display element according to claim 1, wherein at least one of the plurality of display electrodes is an ion-permeable porous electrode.   The display element according to claim 1, wherein an insulating film for insulating the plurality of display electrodes from each other is provided between the plurality of display electrodes.   The display element according to claim 7, wherein the insulating film is a porous inorganic material.

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