Electrochromic element

Abstract

To provide an electrochromic element having high transparency in a discoloured state.SOLUTION: The electrochromic element includes: a first electrochromic layer 104 having a conductive or semiconductor nano structure and electrochromic compound on a first electrode 101; and an electrolyte layer 103 containing electrolyte between the first electrochromic layer 104 and a second electrode 102. The electrochromic compound is a compound represented by the following formula, anion of the electrolyte is monovalent anion with higher oxidation potential by 3.1 V or more than reduction potential of di-cation in the formula.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to an electrochromic element. [Background technology]

[0002] Electrochromism is the phenomenon in which a color changes due to a redox reaction caused by the application of voltage. Generally, electrochromism occurs between two opposing electrodes, and the redox reaction takes place in a configuration where an ion-conducting electrolyte layer fills the space between the electrodes.

[0003] In such electrochromic elements, when attempting to obtain a transparent display element or constructing an element with a stacked structure of three color-producing layers of cyan (C), magenta (M), and yellow (Y), it is important that the element is composed of a reducing electrochromic material that is transparent in its neutral state, or an oxidizing electrochromic material that is transparent in its neutral state. Furthermore, organic electrochromic materials that can be given various colors by substituents are suitable for such vividly colored display elements.

[0004] As the electrochromic material, viologen derivatives that are colorless and transparent in a neutral state and exhibit an electrochromic phenomenon of color development in a reduced state are used. When the viologen derivative is used as the color-developing layer of the device, titanium dioxide is preferably used. Among these, it has been reported that by using titanium dioxide particles as the supported particles of the electrochromic compound in a stacked structure, a layer of viologen derivative can be formed at a very high concentration, thereby achieving high optical density and a high contrast ratio. Furthermore, by forming the viologen derivative as a solid layer, high responsiveness and memory properties can be obtained, which is a significant advantage compared to electrochromic devices consisting of layers using liquids or gels in which the viologen derivative is dissolved in a solvent.

[0005] As such an electrochromic device, for example, an electrochromic device using an electrochromic layer in which a viologen derivative is attached to a conductive or semiconductive nanostructure has been disclosed (see, for example, Patent Document 1). In this device, examples of the counter anion of the viologen derivative include Br ion (Br - ), Cl ion (Cl - ), I ion (I - ), OTf (triflate) ion (OTf - ), ClO4 ion (ClO4 - ), PF6 ion (PF6 - ), and BF4 ion (BF4 - ). As another example, Patent Document 2 also discloses an electrochromic device. In this device, examples of the counter anion of the viologen derivative include Br ion (Br - ), Cl ion (Cl - ), ClO4 ion (ClO4-), PF6 ion (PF6 - ), BF4 ion (BF4 - ), TFSI ion (C2F6NO4S2 - ), and FSI ion (CF3SO3 - ). These counter anions are not particularly limited, and as specific examples, only Br - and Cl - are described. In addition, these documents do not mention at all how various characteristics of the device change depending on the type of counter anion.

[0006] On the other hand, many devices using solutions or gels of viologen derivatives dissolved in a solvent have been disclosed. For example, Patent Document 3 discloses a device in which a viologen derivative is dissolved in a solvent, gelled, and then stacked. Patent Document 4 also discloses a configuration in which a solution of a viologen derivative is sandwiched between electrodes. Furthermore, as a viologen derivative to be used in a solution system, Patent Document 5 discloses, for example, an aryl viologen derivative. However, while several specific anions of viologen derivatives are presented in these devices or materials, they are not necessarily limited, and in particular, there is no mention of the differences in properties depending on the type of anion. The fact that several specific anions are presented is that they were selected solely from the perspective of being inert to oxidation-reduction reactions in the device, as is explicitly stated in Patent Document 6, for example. [Overview of the project] [Problems that the invention aims to solve]

[0007] The object of this invention is to provide an electrochromic element that has high transparency in a decolorized state. [Means for solving the problem]

[0008] An example of a means to solve the above problems is an electrochromic element, which has the following configuration, for example. The first electrode and A second electrode is provided opposite to the first electrode at a distance from it, A first electrochromic layer having a conductive or semiconducting nanostructure and an electrochromic compound is provided on the first electrode. The first electrochromic layer and the second electrode are separated by an electrolyte layer containing an electrolyte, The electrochromic compound is a compound represented by the following general formula 1, The electrochromic element is characterized in that the anion of the electrolyte is a monovalent anion having an oxidation potential 3.1V or higher than the reduction potential of the dication in the general formula 1. [General formula 1] [ka] In the general formula 1 described above, R1 and R2 represent functional groups that can be bonded to a hydrogen atom, an aryl group having up to 14 carbon atoms, a heteroaryl group having up to 14 carbon atoms, a branched alkyl group having up to 10 carbon atoms, an alkenyl group having up to 10 carbon atoms, or a cycloalkyl group having up to 10 carbon atoms, or a hydroxyl group, respectively. And, R 1 and R 2 At least one of these is a phosphonic acid group, a phosphate group, a carboxylic acid group, a sulfonyl group, a silyl group, and a silanol group. R3 and R4 represent alkylene groups with 1 to 10 carbon atoms. In the above general formula 1, Z is selected from the divalent groups of alkylene, cycloalkylene, and R7-Y-R8 (wherein R7 and R8 are each independently selected from a single bond, alkylene, and cycloalkylene, and Y is selected from arylene, cycloalkylene, heteroarylene, arylene-arylene, and arylene-CR'R''-arylene, where R' and R'' form a carbocyclic group together with the carbon to which they are bonded). The alkylene, cycloalkylene, arylene, heteroarylene, and carbocyclic group may be substituted with one or more substituents selected from halogen, alkyl, alkoxy, alkylthio, hydroxyalkyl, acyloxy, cycloalkyl, aryl, substituted aryl, aryloxy, heteroaryl, and substituted heteroaryl. k represents 0 or 1. In the general formula 1, X - This represents a monovalent anion having an oxidation potential at least 3.1 V higher than the reduction potential of the dication in the general formula 1. In the above general formula 1, W 2+ This represents a dication represented by the following general formula 2. [General formula 2] [ka] In the above general formula 2, o, p, and q each independently represent 0 or 1, and A, B, and C each independently represent an arylene group or heterocyclic group having 2 to 20 carbon atoms, which may have substituents.

[0009] Another example of a means to solve the above problems is an electrochromic element, which has, for example, the following configuration. The first electrode and A second electrode is provided opposite to the first electrode at a distance from it, On the first electrode, a first electrochromic layer is provided, which is obtained by depositing an electrochromic compound onto a conductive or semiconducting nanostructure. The first electrochromic layer and the second electrode are separated by an electrolyte layer. An electrochromic element characterized in that the electrochromic compound is a compound represented by the following general formula 1. [General formula 1] [ka] In the general formula 1 described above, R1 and R2 represent functional groups that can be bonded to a hydrogen atom, an aryl group having up to 14 carbon atoms, a heteroaryl group having up to 14 carbon atoms, a branched alkyl group having up to 10 carbon atoms, an alkenyl group having up to 10 carbon atoms, or a cycloalkyl group having up to 10 carbon atoms, or a hydroxyl group, respectively. And, R 1 and R 2 At least one of these is a phosphonic acid group, a phosphate group, a carboxylic acid group, a sulfonyl group, a silyl group, and a silanol group. R3 and R4 represent alkylene groups with 1 to 10 carbon atoms. In the above general formula 1, Z is selected from the divalent groups of alkylene, cycloalkylene, and R7-Y-R8 (wherein R7 and R8 are each independently selected from a single bond, alkylene, and cycloalkylene, and Y is selected from arylene, cycloalkylene, heteroarylene, arylene-arylene, and arylene-CR'R''-arylene, where R' and R'' form a carbocyclic group together with the carbon to which they are bonded). The alkylene, cycloalkylene, arylene, heteroarylene, and carbocyclic group may be substituted with one or more substituents selected from halogen, alkyl, alkoxy, alkylthio, hydroxyalkyl, acyloxy, cycloalkyl, aryl, substituted aryl, aryloxy, heteroaryl, and substituted heteroaryl. k represents 0 or 1. In the general formula 1, X - This represents a monovalent anion having an oxidation potential at least 3.1 V higher than the reduction potential of the dication in the general formula 1. In the above general formula 1, W 2+ This represents a dication represented by the following general formula 2. [General formula 2] [ka] In the above general formula 2, o, p, and q each independently represent 0 or 1, and A, B, and C each independently represent an arylene group or heterocyclic group having 2 to 20 carbon atoms, which may have substituents. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide an electrochromic element that has high transparency in a decolorized state. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a schematic diagram showing an example of the configuration of the electrochromic element of the present invention. [Modes for carrying out the invention]

[0012] The reason why viologen derivative anions can be used in solution systems without being particularly affected by their type is that in such solution systems, the viologen derivative does not actually exist in the form of a complex or ion pair, but rather dissociates ionically after dissolving in the solvent and exists as a solvated free cation. Therefore, it exhibits the same behavior as a viologen derivative cation, regardless of the type of the original counterion. Even if it were to be affected by relatively nearby free anions, these solution systems usually contain a much larger amount of electrolyte than the viologen derivative, and the influence of the anions in this electrolyte becomes dominant, so it is still largely unaffected by the type of the original counterion.

[0013] In contrast, in environments where viologen derivatives exist as ion pairs or complexes, with little or no solvent or other ions between the viologen derivative molecules, and where viologen derivatives are present at very high concentrations, the properties of the viologen derivative are strongly influenced by the type of counteranion. Such environments refer to cases where viologen derivatives are used in a solid state or supported on a carrier, and a typical example is an electrochromic device using an electrochromic layer in which a viologen derivative is attached to a conductive or semiconducting nanostructure. Therefore, the inventors have found that the significant change in the device's properties depending on the type of counteranion of the viologen derivative is a problem unique to electrochromic devices using an electrochromic layer having a viologen derivative and a conductive or semiconducting nanostructure.

[0014] However, as mentioned above, the influence of the type of counteranion on such electrochromic elements has not been sufficiently studied to date.

[0015] Therefore, the inventors diligently investigated the types of counteranions of dications in electrochromic elements having an electrochromic layer comprising a specific dication (a compound represented by the general formula A below) such as a viologen derivative and a conductive or semiconducting nanostructure. They discovered that the transparency of the element in its decolorized state differs depending on the type of counteranion. [General formula 1] [ka] In the above general formula 1, R1 and R2 each represent a functional group that can be bonded to a hydrogen atom, an aryl group having up to 14 carbon atoms, a heteroaryl group having up to 14 carbon atoms, a branched alkyl group having up to 10 carbon atoms, an alkenyl group having up to 10 carbon atoms, or a cycloalkyl group or hydroxyl group having up to 10 carbon atoms. R3 and R4 each represent an alkylene group having 1 to 10 carbon atoms or an arylene group having up to 12 carbon atoms which may have substituents. In the above general formula 1, Z is selected from the divalent groups of alkylene, cycloalkylene, and R7-Y-R8 (wherein R7 and R8 are each independently selected from a single bond, alkylene, and cycloalkylene, and Y is selected from arylene, cycloalkylene, heteroarylene, arylene-arylene, and arylene-CR'R''-arylene, where R' and R'' form a carbocyclic group together with the carbon to which they are bonded). The alkylene, cycloalkylene, arylene, heteroarylene, and carbocyclic group may be substituted with one or more substituents selected from halogen, alkyl, alkoxy, alkylthio, hydroxyalkyl, acyloxy, cycloalkyl, aryl, substituted aryl, aryloxy, heteroaryl, and substituted heteroaryl. k represents 0 or 1. In the general formula 1, X - This represents an ion that neutralizes charge. In the above general formula 1, W 2+ This represents a dication represented by the following general formula 2. [General formula 2] [ka] In the above general formula 2, o, p, and q each independently represent 0 or 1, and A, B, and C each independently represent an arylene group or heterocyclic group having 2 to 20 carbon atoms, which may have substituents. Further investigations revealed that by using a monovalent anion with an oxidation potential 3.1V or higher than the reduction potential of the dication in general formula 1 as the anion of the specific dication, high transparency is achieved in the decolorized state, thus completing the present invention.

[0016] In this invention, having high transparency in the decolorized state means that the first electrochromic layer has a low YI (Yellow Index) value. That is, even if the YI value of the element itself is high due to the coloring of the electrodes, if the YI value of the first electrochromic layer is kept low, it will be considered to have high transparency in the decolorized state.

[0017] Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

[0018] (Electrochromic element) Figure 1 shows an example of the configuration of the electrochromic element of the present invention. The electrochromic element has a first electrode 101, a second electrode 102, an electrolyte layer 103, a first electrochromic layer 104, and a second electrochromic layer 105.

[0019] The electrochromic element of the present invention includes, for example, the following first and second embodiments.

[0020] <First aspect> A first aspect of the electrochromic element of the present invention is The first electrode and A second electrode is provided opposite to the first electrode at a distance from it, On the first electrode, a first electrochromic layer is provided, which is obtained by depositing an electrochromic compound onto a conductive or semiconducting nanostructure. The first electrochromic layer and the second electrode are separated by an electrolyte layer. The electrochromic compound is a compound represented by the following general formula 1. [General formula 1] [ka] In the above general formula 1, R1 and R2 each represent a functional group that can be bonded to a hydrogen atom, an aryl group having up to 14 carbon atoms, a heteroaryl group having up to 14 carbon atoms, a branched alkyl group having up to 10 carbon atoms, an alkenyl group having up to 10 carbon atoms, or a cycloalkyl group or hydroxyl group having up to 10 carbon atoms. R3 and R4 each represent an alkylene group having 1 to 10 carbon atoms or an arylene group having up to 12 carbon atoms which may have substituents. In the above general formula 1, Z is selected from the divalent groups of alkylene, cycloalkylene, and R7-Y-R8 (wherein R7 and R8 are each independently selected from a single bond, alkylene, and cycloalkylene, and Y is selected from arylene, cycloalkylene, heteroarylene, arylene-arylene, and arylene-CR'R''-arylene, where R' and R'' form a carbocyclic group together with the carbon to which they are bonded). The alkylene, cycloalkylene, arylene, heteroarylene, and carbocyclic group may be substituted with one or more substituents selected from halogen, alkyl, alkoxy, alkylthio, hydroxyalkyl, acyloxy, cycloalkyl, aryl, substituted aryl, aryloxy, heteroaryl, and substituted heteroaryl. k represents 0 or 1. In the general formula 1, X - This represents a monovalent anion (hereinafter sometimes referred to as a "high oxidation potential anion") that has an oxidation potential 3.1 V or higher than the reduction potential of the dication in the general formula 1. In the above general formula 1, W 2+ This represents a dication represented by the following general formula 2. [General formula 2] [ka] In the above general formula 2, o, p, and q each independently represent 0 or 1, and A, B, and C each independently represent an arylene group or heterocyclic group having 2 to 20 carbon atoms, which may have substituents.

[0021] An important aspect of the first embodiment is that the first electrochromic layer is obtained by attaching the electrochromic compound to a conductive or semiconducting nanostructure. That is, when forming the first electrochromic layer by attaching the electrochromic compound to a conductive or semiconducting nanostructure, the high oxidation potential anion is used as the anion of the electrochromic compound. Comparing the examples and comparative examples in this specification, the examples use the compound of general formula 1 when forming the first electrochromic layer. On the other hand, in the comparative examples, when forming the first electrochromic layer, instead of the anion of the compound of general formula 1, a monovalent anion (Br) having an oxidation potential not higher than 3.1V than the reduction potential of the dication in general formula 1 is used. - Cl - (Hereafter, this may be referred to as "low oxidation potential anions") In the electrochromic devices of the examples described herein, a low YI value is obtained during device fabrication due to the high oxidation potential anion, and this state is maintained for a long time. On the other hand, in the electrochromic elements of the comparative examples described herein, a high YI value is obtained during the fabrication of the element due to the low oxidation potential anion, and this state is maintained for a long time. Generally, after the fabrication of an electrochromic device, ion exchange occurs between the anions in the electrolyte layer and the anions in the first electrochromic layer. Although the extent of ion exchange is not clear, it is expected to be 50% or more. Therefore, the anions contained in the electrolyte layer at the time of device fabrication are exchanged to some extent with the anions contained in the first electrochromic layer at the time of device fabrication, and in the electrochromic device of the comparative example described herein, after device fabrication, the anions contained in the electrolyte layer are contained in the first electrochromic layer. Once ion exchange occurs, it is nearly impossible to determine the amount of ion-exchanged anions from the device after ion exchange. This is because, after ion exchange has occurred, it is not possible to analyze whether the anions contained in the first electrochromic layer and the anions contained in the electrolyte layer of the device after ion exchange were the anions used to form the first electrochromic layer or the anions used to form the electrolyte layer during device fabrication. In the comparative electrochromic device described herein, the high oxidation potential anion is used to form the electrolyte layer during device fabrication. In this case, when ion exchange occurs, the high oxidation potential anion will be present in the first electrochromic layer of the comparative device after ion exchange, but even then, it maintains a YI value that is high enough to be distinguishable from the YI value of the example. Therefore, in both the examples and comparative examples of this specification, although there is a state in the first electrochromic layer with the high oxidation potential anion after the device is fabricated, the YI values ​​of the examples and comparative examples in those states are clearly different. However, in both the examples and comparative examples of this specification, ion exchange occurs after the device is fabricated, and it is impossible or impractical to distinguish between these states by analysis when there is a state in the first electrochromic layer with the high oxidation potential anion. This is impossible or impractical, for example, because it is impossible to analyze the differences between the following two devices (the first device and the second device) after they are fabricated and after ion exchange. • First element: An element in which, during the fabrication of the element, one unit of the high oxidation potential anion is used to form the first electrochromic layer, and a mixture of the high oxidation potential anion and the low oxidation potential anion (a mixture of 50 units:50 units) is used to form the electrolyte layer. • Second element: An element in which, during the fabrication of the element, one unit of the low oxidation potential anion is used to form the first electrochromic layer, and a mixture of the high oxidation potential anion and the low oxidation potential anion (a mixture of 49 units and 51 units) is used to form the electrolyte layer. In the first and second elements, after ion exchange of approximately 50% or more of the anions in the first electrochromic layer has occurred between the first electrochromic layer and the electrolyte layer, it is no longer possible to distinguish by analysis the difference in the amounts of the high oxidation potential anions and the low oxidation potential anions present in the first electrochromic layer and the electrolyte layer, respectively, between the first and second elements. Therefore, an important point in the first embodiment is that the first electrochromic layer is obtained by attaching the electrochromic compound to a conductive or semiconducting nanostructure. That is, when forming the first electrochromic layer by attaching the electrochromic compound to a conductive or semiconducting nanostructure, the high oxidation potential anion is used as the anion of the electrochromic compound. This point is particularly important under conditions where the anion used to form the electrolyte layer is not limited.

[0022] <Second aspect> A second aspect of the electrochromic element of the present invention is: The first electrode and A second electrode is provided opposite to the first electrode at a distance from it, A first electrochromic layer having a conductive or semiconducting nanostructure and an electrochromic compound is provided on the first electrode. The first electrochromic layer and the second electrode are separated by an electrolyte layer containing an electrolyte, The electrochromic compound is a compound represented by the following general formula 1, The anion of the electrolyte is a monovalent anion having an oxidation potential 3.1 V or higher than the reduction potential of the dication in the general formula 1. [General formula 1] [ka] In the above general formula 1, R1 and R2 each represent a functional group that can be bonded to a hydrogen atom, an aryl group having up to 14 carbon atoms, a heteroaryl group having up to 14 carbon atoms, a branched alkyl group having up to 10 carbon atoms, an alkenyl group having up to 10 carbon atoms, or a cycloalkyl group or hydroxyl group having up to 10 carbon atoms. R3 and R4 each represent an alkylene group having 1 to 10 carbon atoms or an arylene group having up to 12 carbon atoms which may have substituents. In the above general formula 1, Z is selected from the divalent groups of alkylene, cycloalkylene, and R7-Y-R8 (wherein R7 and R8 are each independently selected from a single bond, alkylene, and cycloalkylene, and Y is selected from arylene, cycloalkylene, heteroarylene, arylene-arylene, and arylene-CR'R''-arylene, where R' and R'' form a carbocyclic group together with the carbon to which they are bonded). The alkylene, cycloalkylene, arylene, heteroarylene, and carbocyclic group may be substituted with one or more substituents selected from halogen, alkyl, alkoxy, alkylthio, hydroxyalkyl, acyloxy, cycloalkyl, aryl, substituted aryl, aryloxy, heteroaryl, and substituted heteroaryl. k represents 0 or 1. In the general formula 1, X - This represents a monovalent anion having an oxidation potential at least 3.1 V higher than the reduction potential of the dication in the general formula 1. In the above general formula 1, W 2+ This represents a dication represented by the following general formula 2. [General formula 2] [ka] In the above general formula 2, o, p, and q each independently represent 0 or 1, and A, B, and C each independently represent an arylene group or heterocyclic group having 2 to 20 carbon atoms, which may have substituents.

[0023] In the second embodiment, an element with superior transparency can be obtained even when ion exchange occurs between the anions of the electrochromic compound and the anions of the electrolyte within the element.

[0024] In a second embodiment, the first electrochromic layer has conductive or semiconducting nanostructures and an electrochromic compound on the first electrode. In the second embodiment, the first electrochromic layer is not particularly limited as long as it has a conductive or semiconductive nanostructure and the electrochromic compound described above, and can be appropriately selected depending on the purpose. The first electrochromic layer is preferably one in which the electrochromic compound is attached to a conductive or semiconducting nanostructure. In other words, in the second embodiment, the first electrochromic layer is preferably one in which the electrochromic compound is attached to a conductive or semiconducting nanostructure.

[0025] The following two points are important in the second embodiment: (i) The electrochromic compound in the first electrochromic layer is the compound represented by the general formula 1. (ii) The anions of the electrolyte in the electrolyte layer containing the electrolyte are monovalent anions having an oxidation potential 3.1 V or higher than the reduction potential of the dication in the general formula 1.

[0026] In the first embodiment, when forming a first electrochromic layer by attaching the electrochromic compound to a conductive or semiconducting nanostructure, it is important to use the high oxidation potential anion as the anion of the electrochromic compound. This is especially important under conditions where the anion used for forming the electrolyte layer is not limited. On the other hand, in the second embodiment, in addition to the electrochromic compound in the first electrochromic layer being the compound represented by general formula 1, the anion in the electrolyte of the electrolyte layer is the high oxidation potential anion. In this case, since the anions present in the first electrochromic layer and the electrolyte layer are substantially only the high oxidation potential anion, even if these anions undergo ion exchange, the state of the high oxidation potential anion present in the first electrochromic layer and the electrolyte layer remains almost unchanged. In a second embodiment, the fact that the electrochromic compound in the first electrochromic layer is a compound represented by the general formula 1, and that the anion of the electrolyte is a monovalent anion having an oxidation potential 3.1 V or higher than the reduction potential of the dication in the general formula 1, may occur before or after anion exchange between the first electrochromic layer and the electrolyte layer. In the second embodiment, the electrolyte layer may contain trace amounts to about 10 mol% of the total amount of anions of the low oxidation potential anions. Furthermore, the first electrochromic layer may contain trace amounts to about 10 mol% of the total amount of anions of the low oxidation potential anions.

[0027] <First electrochromic layer> In the first embodiment, the first electrochromic layer is obtained by depositing an electrochromic compound onto a conductive or semiconducting nanostructure. In a second embodiment, the first electrochromic layer comprises a conductive or semiconducting nanostructure and an electrochromic compound. In a second embodiment, it is preferable that the first electrochromic layer is obtained by attaching an electrochromic compound to a nanostructure.

[0028] In this invention, "adhesion" refers to a state in which particles are chemically bonded by means such as covalent bonds or ionic bonds, a state in which particles are physically adsorbed by means such as hydrogen bonds or intermolecular forces, and a state in which particles or amorphous solids are physically deposited, but is not limited to these.

[0029] As a method for forming the first electrochromic layer, for example, vacuum deposition, sputtering, ion plating, etc., can be used. Furthermore, if the material for the first electrochromic layer can be coated, various printing methods can be used, such as spin coating, casting, microgravure coating, gravure coating, bar coating, roll coating, wire bar coating, dip coating, slit coating, capillary coating, spray coating, nozzle coating, gravure printing, screen printing, flexographic printing, offset printing, reverse printing, inkjet printing, etc. For example, by forming the first electrochromic layer using the method shown in the examples of this specification, a first electrochromic layer can be produced in which an electrochromic compound is attached to a conductive or semiconducting nanostructure.

[0030] The average thickness of the first electrochromic layer is not particularly limited and can be appropriately selected depending on the purpose, but it is preferably 0.2 μm or more and 5.0 μm or less. If the average thickness is 0.2 μm or more, a high color density can be easily obtained, and if it is 5.0 μm or less, manufacturing costs can be reduced and a decrease in visibility due to coloring is less likely to occur. The first electrochromic layer can also be formed by vacuum deposition, but in terms of productivity, it is preferable to form it by coating as a particle dispersion paste.

[0031] The first electrochromic layer is stacked on the first electrode, and may consist of only one layer or two or more layers.

[0032] The electrochromic compound may be attached after the conductive or semiconducting nanostructure has been formed. In this case, the conductive or semiconducting nanostructure can be formed using the same method as the first electrochromic layer formation method. For example, the method for attaching the electrochromic compound can be vacuum deposition, sputtering, ion plating, etc. In addition, various printing methods such as spin coating, casting, microgravure coating, gravure coating, bar coating, roll coating, wire bar coating, dip coating, slit coating, capillary coating, spray coating, nozzle coating, gravure printing, screen printing, flexographic printing, offset printing, reverse printing, and inkjet printing can be used.

[0033] <<Conductive or semiconducting nanostructures>>

[0034] The conductive or semiconducting nanostructure according to the present invention is a structure having nanoscale irregularities, such as nanoparticles or nanoporous structures.

[0035] As the material constituting the conductive or semiconducting nanostructure, metal oxides are preferred in terms of transparency and conductivity. Examples of such metal oxides include those mainly composed of titanium oxide, zinc oxide, tin oxide, zirconium oxide, cerium oxide, yttrium oxide, boron oxide, 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, vanadium oxide, aluminosilicate, calcium phosphate, and aluminosilicate. These metal oxides may be used individually or in mixtures of two or more.

[0036] Considering electrical properties such as electrical conductivity and physical properties such as optical properties, when one or a mixture thereof of metal oxides selected from titanium oxide, zinc oxide, tin oxide, zirconium oxide, iron oxide, magnesium oxide, indium oxide, and tungsten oxide is used, the response speed of color change is excellent. In particular, when titanium oxide is used, the response speed of color change is even better.

[0037] The shape of the metal oxide is preferably a metal oxide nanoparticle with an average primary particle diameter of 30 nm or less. The smaller the particle diameter, the better the light transmittance to the metal oxide, and a shape with a large surface area per unit volume (hereinafter referred to as "specific surface area") is used. Having a large specific surface area allows the electrochromic compound to be supported more efficiently, enabling multi-color display with excellent display contrast ratio of color change. The specific surface area of ​​the nanostructure is not particularly limited, but for example, 100 m 2 It can be 1g or more.

[0038] <<Electrochromic Compounds>> The electrochromic compound of the present invention is a compound represented by the following general formula 1. [General formula 1] [ka] In the above general formula 1, R1 and R2 each represent a functional group that can be bonded to a hydrogen atom, an aryl group having up to 14 carbon atoms, a heteroaryl group having up to 14 carbon atoms, a branched alkyl group having up to 10 carbon atoms, an alkenyl group having up to 10 carbon atoms, or a cycloalkyl group or hydroxyl group having up to 10 carbon atoms. R3 and R4 each represent an alkylene group having 1 to 10 carbon atoms or an arylene group having up to 12 carbon atoms which may have substituents. In the above general formula 1, Z is selected from the divalent groups of alkylene, cycloalkylene, and R7-Y-R8 (wherein R7 and R8 are each independently selected from a single bond, alkylene, and cycloalkylene, and Y is selected from arylene, cycloalkylene, heteroarylene, arylene-arylene, and arylene-CR'R''-arylene, where R' and R'' form a carbocyclic group together with the carbon to which they are bonded). The alkylene, cycloalkylene, arylene, heteroarylene, and carbocyclic group may be substituted with one or more substituents selected from halogen, alkyl, alkoxy, alkylthio, hydroxyalkyl, acyloxy, cycloalkyl, aryl, substituted aryl, aryloxy, heteroaryl, and substituted heteroaryl. k represents 0 or 1. In the general formula 1, X - This represents a monovalent anion having an oxidation potential at least 3.1 V higher than the reduction potential of the dication in the general formula 1. In the above general formula 1, W 2+ This represents a dication represented by the following general formula 2. [General formula 2] [ka] In the above general formula 2, o, p, and q each independently represent 0 or 1, and A, B, and C each independently represent an arylene group or heterocyclic group having 2 to 20 carbon atoms, which may have substituents.

[0039] In the above general formula 1, W 2+ R1 exhibits electrochromic function, and the color changes through oxidation-reduction of this part. R1, R2, R3, R4 and Z do not contribute to electrochromic function, and W 2+ It does not inhibit the electrochromic function.

[0040] A more preferred embodiment is a functional group in which at least one of R1 or R2 can bond to a hydroxyl group. This facilitates attachment to the conductive or semiconducting nanostructure. A more preferable configuration is one in which both R1 and R2 are functional groups capable of bonding to the hydroxyl group. This results in a stronger bond, reducing the possibility of detachment within the device and leading to improved reliability. Another preferred embodiment is a functional group in which either R1 or R2 can bond to the hydroxyl group. This allows more electrochromic compounds to adhere to the conductive or semiconductive nanostructure, leading to an improvement in color intensity.

[0041] Examples of functional groups that can be bonded to the hydroxyl group include phosphonic acid groups, phosphoric acid groups, carboxylic acid groups, sulfonyl groups, silyl groups, and silanol groups. Among these, phosphonic acid groups, phosphoric acid groups, and carboxylic acid groups are preferred, with phosphonic acid groups being more preferred, from the viewpoint of ease of synthesis, adsorption to supported particles, and stability of the compound. Examples of silyl groups include the following alkoxysilyl groups. -SiR 100 n (OR 101 ) 3-n In the above formula, R 100 R represents an alkyl group with 1 to 4 carbon atoms. 101 R represents an alkoxy group with 1 to 4 carbon atoms. n represents an integer from 0 to 2. 100 However, if there are two or more, they may be the same or different. 101 However, if there are two or more, they may be the same or different.

[0042] Thus, in the present invention, for example, it is preferable that at least one of R1 and R2 in the general formula 1 is one of a phosphonic acid group, a phosphoric acid group, a carboxylic acid group, a sulfonyl group, a silyl group, and a silanol group. This makes it possible to easily adhere to the conductive or semiconducting nanostructure. In this case, in the present invention, for example, if R1 and R2 (both R1 and R2) in the general formula 1 are any of the following: a phosphonic acid group, a phosphoric acid group, a carboxylic acid group, a sulfonyl group, a silyl group, and a silanol group, the bond becomes stronger, the possibility of detachment within the device is reduced, and reliability can be improved. Furthermore, in the present invention, if either R1 or R2 in the general formula 1 is one of a phosphonic acid group, a phosphoric acid group, a carboxylic acid group, a sulfonyl group, a silyl group, or a silanol group, and the other is one of a hydrogen atom, an aryl group having up to 14 carbon atoms, a heteroaryl group having up to 14 carbon atoms, a branched alkyl group having up to 10 carbon atoms, an alkenyl group having up to 10 carbon atoms, or a cycloalkyl group having up to 10 carbon atoms, then more electrochromic compounds can adhere to the conductive or semiconductive nanostructure, thereby improving the color intensity.

[0043] When the electrochromic compound has functional groups such as phosphonic acid, phosphate, carboxyl, and sulfonyl groups, it adheres to the nanostructure even more readily. Furthermore, when the electrochromic compound has silyl and silanol groups, it adheres to the nanostructure via siloxane bonds, and these bonds become strong, allowing for the creation of a stable electrochromic layer. The siloxane bond refers to a chemical bond mediated by silicon and oxygen atoms.

[0044] Examples of the phosphonic acid group include methylphosphonic acid group, ethylphosphonic acid group, propylphosphonic acid group, hexylphosphonic acid group, octylphosphonic acid group, decylphosphonic acid group, dodecylphosphonic acid group, octadecylphosphonic acid group, benzylphosphonic acid group, phenylethylphosphonic acid group, phenylpropylphosphonic acid group, and biphenylphosphonic acid group. Examples of the phosphate group include methyl phosphate group, ethyl phosphate group, propyl phosphate group, hexyl phosphate group, octyl phosphate group, decyl phosphate group, dodecyl phosphate group, octadecyl phosphate group, benzyl phosphate group, phenylethyl phosphate group, phenylpropyl phosphate group, and biphenyl phosphate group. Examples of the carboxylic acid group include methyl carboxylic acid group, ethyl carboxylic acid group, propyl carboxylic acid group, hexyl carboxylic acid group, octyl carboxylic acid group, decyl carboxylic acid group, dodecyl carboxylic acid group, octadecyl carboxylic acid group, benzyl carboxylic acid group, phenylethyl carboxylic acid group, phenylpropyl carboxylic acid group, biphenyl carboxylic acid group, 4-propylphenyl carboxylic acid group, and 4-propylbiphenyl carboxylic acid group.

[0045] Examples of the sulfonyl group include methylsulfonyl group, ethylsulfonyl group, propylsulfonyl group, hexylsulfonyl group, octylsulfonyl group, decylsulfonyl group, dodecylsulfonyl group, octadecylsulfonyl group, benzylsulfonyl group, phenylethylsulfonyl group, phenylpropylsulfonyl group, and biphenylsulfonyl group. Examples of the silyl group include methylsilyl group, ethylsilyl group, propylsilyl group, hexylsilyl group, octylsilyl group, decylsilyl group, dodecylsilyl group, octadecylsilyl group, benzylsilyl group, phenylethylsilyl group, phenylpropylsilyl group, and biphenylsilyl group. Examples of the silanol group include methylsilanol group, ethylsilanol group, propylsilanol group, hexylsilanol group, octylsilanol group, decylsilanol group, dodecylsilanol group, octadecylsilanol group, benzylsilanol group, phenylethylsilanol group, phenylpropylsilanol group, and biphenylsilanol group.

[0046] In the above general formula 1, Z is C1-C12 alkylene, C3-C7 cycloalkylene, C3-C14 arylene, C5-C10 heteroarylene, (C1-C4 alkylene)-(C3-C14 arylene), (C1-C4 alkylene)-(C3-C14 heteroarylene), (C1-C4 alkylene)-(C3-C14 arylene)-(C1-C4 alkylene), (C1-C4 alkylene)-(C3-C14 heteroarylene)-(C1-C4 alkylene), (C3-C14 arylene)-(C3-C14 arylene), (C1-C4 alkylene)-(C3-C14 arylene)-(C3-C14 arylene)-(C1-C4 alkylene), and (C3-C14 Preferably selected from arylene)-(CR'R'')-(C3-C14 arylene), where R' and R'' together with the carbon to which they are bonded form a C3-C20 carbocyclic group; the arylene and cycloalkylene groups may be substituted with one or more substituents selected from halogens, C1-C4 alkyls, C1-C4 alkoxys, and C3-C7 cycloalkyls, and the alkylene group may be substituted with one or more substituents selected from halogens, C3-C14 alkyls, C1-C12 alkoxys, C2-C12 acyloxys, C1-C12 hydroxyalkyls, C3-C12 cycloalkyls, phenyls, phenyloxys, and substituted phenyls. Specifically, the substituted alkylene comprises -CH2(CRaRb)CH2-, where Ra and Rb may be independently selected from H, C3-C14 alkyl, C3-C12 cycloalkyl, (cycloalkyl)methyl, aryl, substituted aryl, arylalkyl (e.g., benzyl or phenyl(C2-C7 alkyl)), phenyloxyethyl, substituted arylalkyl, C1-C12 alkoxy, C2-C12 acyloxy, C1-C12 hydroxyalkyl, and C1-C12 alkoxymethyl.

[0047] It is even more preferable that Z is selected from C1-C12 alkylenes, aryl-substituted C1-C12 alkylenes, phenylene, naphthylene, (C1-C4 alkylene)-phenylene-(C1-C4 alkylene), (C1-C4 alkylene)-naphthylene-(C1-C4 alkylene) (e.g., naphthylenebis(methylene), etc.), quinoxaline-2,3-diyl, (C1-C4 alkylene)-quinoxaline-2,3-diyl-(C1-C4 alkylene) (e.g., quinoxaline-2,3-diylbis(methylene), etc.), phenylene-phenylene, (C1-C4 alkylene)-phenylene-phenylene-(C1-C4 alkylene), and phenylene-fluorenylene-phenylene. Examples of Z include -CH2-, -(CH2)2-, -(CH2)3-, -(CH2)4-, -(CH2)5-, -CH2-CH(CH3)-CH2-, -CH2-CH(CH2phenyl)-CH2-, -(CH2)2-CH(CH3)-CH2-, -(CH2)3-CH(CH3)-CH2-, and -(CH2)2-CH(CH3)-(CH2)2-.

[0048] Furthermore, as Z in the general formula 1, the one represented by the following structural formula can be suitably used. [ka]

[0049] In the above general formula 1, X - The oxidation potential of X is 3.1V or more higher than the reduction potential of the dication in the general formula 1. In other words, X - This represents a monovalent anion with an oxidation potential at least 3.1 V higher than the reduction potential of the dication in the general formula 1. -If the oxidation potential of the element is not 3.1V higher than the reduction potential of the dication in general formula 1, the element may be slightly colored in its decolorized state, resulting in reduced transmittance. When an electrochromic compound is attached to a conductive or semiconducting nanostructure, the anion and the dication (the dication in general formula 1) may form a CT (Charge Transfer) complex, and light of a certain wavelength may be absorbed by the CT transition. In this case, if the absorption wavelength due to the CT transition is greater than 400nm, that is, if the energy level difference between the anion's LUMO (Lowest Unoccupied Molecular Orbital) and the dication's HOMO (Highest Occupied Molecular Orbital) is less than 3.1eV, i.e., if the potential difference between the anion's oxidation potential and the dication's reduction potential is less than 3.1V, the electrochromic element will appear colored to the naked eye, which is undesirable. In such cases, the element often appears yellow due to a decrease in transmittance, especially in the short wavelength range.

[0050] X when the potential difference between the oxidation potential of the anion and the reduction potential of the dication is 3.1V or more - For example, (FSO2)2N - (CF3SO2)2N - (CN)4B - BF4 - CF3BF3 - PF6 - ClO4 - (C2F5SO2)2N - (C4F9SO2)2N - , CF3SO3, C2F5SO3, C4F9SO3, (C2F5)3PF3 - , (CF3SO2)3C - These are some examples. These can be used individually or in combination.

[0051] In a more preferred embodiment, X - (FSO2)2N - (CF3SO2)2N - (CN)4B -BF4 - PF6 - ClO4 - It is one or more types selected from the following. These anions are large enough to not easily form CT complexes with dications, are stable, and are not too large to obtain a sufficient response speed. Therefore, by using these anions, it is possible to obtain devices that are not only highly transparent but also highly responsive.

[0052] In a more preferred embodiment, X - (FSO2)2N - (CF3SO2)2N - It is one or more types selected from the following. These anions are particularly excellent in stability and responsiveness, and by using these anions, it is possible to obtain devices with even greater durability.

[0053] As the most preferred embodiment, X - (CF3SO2)2N - (hereinafter referred to as “TFSI - It is sometimes referred to as (CF3SO2)2N. - By using this method, it is possible to obtain a device that can achieve an even higher color density. The mechanism is not yet clear, but it is thought that the adhesion state, such as the distance between dication molecules, the packing structure, and the surface state of the conductive or semiconducting nanostructure during the adhesion process, are influencing the adhesion of the electrochromic compound to the nanostructure. It is presumed that the surface state of the conductive or semiconducting nanostructure during the adhesion process changes depending on the wettability and pH of the solution when the electrochromic compound solution is applied to the nanostructure.

[0054] In a preferred form of the electrochromic compound, W in the general formula 1 2+ This is represented by the following structural formula 1. This increases the stability of the dication's coloration state, resulting in a more reliable device. [Structural formula 1] [ka]

[0055] In another preferred embodiment of the electrochromic compound, k in general formula 1 is 0. This increases the solubility of the compound, making it easier to attach more of the electrochromic compound to the conductive or semiconducting nanostructure, leading to an improvement in color intensity.

[0056] In yet another preferred embodiment of the electrochromic compound, R3 in general formula 1 is represented by the following general formula 3, and R4 is represented by the following general formula 4. This increases the durability of the electrochromic compound and makes it possible to obtain a more reliable device. [General formula 3] [ka] [General formula 4] [ka] However, in the general formula 3, m represents an integer from 0 to 10, and in the general formula 4, n represents an integer from 0 to 10, and m and n may be the same value or different values.

[0057] Specific examples of electrochromic compounds of the present invention are listed below, but the electrochromic compounds are not limited to these.

[0058] <Example Compound 1-1> [ka]

[0059] <Example Compounds 1-2> [ka]

[0060] <Example Compounds 1-3>

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[0061] <Exemplary compound 1-4>

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[0062] <Exemplary compound 1-5>

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[0063] <Exemplary compound 1-6>

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[0064] <Exemplary compound 1-7>

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[0065] <Exemplary compound 1-8>

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[0066] <Exemplary compound 1-9>

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[0067] <Exemplary compounds 1-10>

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[0068] <Exemplary compound 1-11>

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[0069] <Exemplary compounds 1-12>

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[0070] <Exemplary compound 1-13>

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[0071] <Exemplary compound 1-14>

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[0072] <Exemplary compound 1-15>

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[0073] <Exemplary compound 1-16>

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[0074] <Exemplary compound 1-17>

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[0075] <Exemplary compound 1-18>

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[0076] <Exemplary compound 1-19>

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[0077] <Exemplary compounds 1-20>

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[0078] <Exemplary compound 1-21>

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[0079] <Exemplary compound 1-22>

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[0080] <Exemplary compound 1-23>

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[0081] <Exemplary compound 1-24>

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[0082] <Exemplary compound 1-25>

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[0083] <Exemplary compound 1-26>

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[0084] <Exemplary compound 1-27>

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[0085] <Exemplary compound 1-28>

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[0086] <Example Compounds 1-29> [ka]

[0087] <Example Compounds 1-30> [ka]

[0088] <Example Compounds 1-31> [ka]

[0089] <Example Compounds 1-32> [ka]

[0090] <Example Compounds 1-33> [ka]

[0091] <Example Compounds 1-34> [ka]

[0092] Various known methods can be used to identify the ion species in the electrochromic layer, with ion chromatography being particularly effective.

[0093] One method of verification involves disassembling the electrochromic element to expose the electrochromic layer, washing the electrochromic layer with a solvent such as water or alcohol, or immersing the electrochromic layer in a solvent to dissolve the electrochromic compound in the solvent. Heating or hydrolysis treatment by adding acids or alkalis may be used in conjunction with this method as needed. Alternatively, to prevent contamination by ions in the electrolyte layer, the electrochromic layer may be washed beforehand, and then the electrochromic compound may be dissolved using the above method. The resulting solution can then be analyzed using ion chromatography to identify the ion species.

[0094] However, during the analytical procedure, OH may be present in the air or other materials. - Caution is necessary because trace amounts of impurities such as halide ions may be present.

[0095] The aforementioned X - The oxidation potential can be measured using known methods, but when measuring electrochemically, for example, it is preferable to use the same measurement method as when measuring the reduction potential of an electrochromic compound. Specifically, it is preferable to use the same working electrode, counter electrode, reference electrode, solvent, electrolyte, and measurement conditions. When measuring the oxidation-reduction potential by cyclic voltammetry, first the electrode potential is swept in the reduction direction to measure the reduction potential of the electrochromic compound of the present invention, and then the electrode potential is swept in the oxidation direction to measure X - Measuring the oxidation potential allows for easy comparison of reaction potentials in the exact same system. On the other hand, due to solubility in the solvent and the potential window of the measurement system, X - If the oxidation potentials of X cannot be measured simultaneously in the same system, - By preparing a salt using a cation with a high potential window on the oxidation side as a counter cation, and measuring the oxidation potential of that salt, X - The oxidation potential can be measured. However, there are not many measurement systems with a wide potential window that can go up to a potential 3.1V or more higher than the reduction potential of the electrochromic compound of the present invention, so X -It is best to estimate the oxidation potential by comparing it with the background current value of the same measurement system that does not contain the salt.

[0096] <Second electrochromic layer> The electrochromic element of the present invention preferably has a second electrochromic layer on the second electrode. The second electrochromic layer contains a second electrochromic compound. Furthermore, the inclusion of the second electrochromic compound in the second electrochromic layer includes not only the embodiment in which the second electrochromic compound maintains its structure, but also the embodiment in which the second electrochromic compound exists as a component of the polymer. In other words, the statement that the second electrochromic layer contains the second electrochromic compound means that the second electrochromic layer contains the second electrochromic compound as a constituent component.

[0097] The presence of a second electrochromic layer allows for the decolorization and decolorization of both electrochromic layers, resulting in a higher color intensity.

[0098] The second electrochromic layer is stacked on the second electrode, and may consist of only one layer or two or more layers.

[0099] <<Second electrochromic compound>> The second electrochromic compound is not particularly limited and any known electrochromic compound can be used.

[0100] Specifically, electrochromic compounds used include low-molecular-weight organic electrochromic materials such as azobenzene, anthraquinone, diarylethene, dihydroprene, styryl, styrylspiropyran, spirooxazine, spirothiopyran, thioindigo, tetrathiafulvalene, terephthalic acid, triphenylmethane, triphenylamine, naphthopyran, viologen, pyrazoline, phenazine, phenylenediamine, phenoxazine, phenothiazine, phthalocyanine, fluorane, flugide, benzopyran, and metallocene, as well as conductive polymer compounds such as polyaniline and polythiophene. These may be used individually or in combination.

[0101] More preferably, the second electrochromic layer contains a polymer obtained by polymerizing a polymerizable material containing a radical polymerizable compound having a triarylamine skeleton. This makes it possible to obtain an electrochromic element with excellent durability. Furthermore, it is preferable that the second electrochromic layer consists essentially of polymers. Here, "essentially consisting solely of polymers" means that the second electrochromic layer may contain other components besides polymers, to the extent that it does not hinder the above-mentioned effects.

[0102] More preferably, the second electrochromic layer contains a polymer obtained by polymerizing a polymerizable material containing a radical polymerizable compound having a triarylamine skeleton and a radical polymerizable compound having a tetraarylbenzidine skeleton. This makes it possible to obtain an electrochromic element with superior durability.

[0103] The radical polymerizable compounds having the triarylamine skeleton and the radical polymerizable compounds having the tetraarylbenzidine skeleton are important for imparting electrochromic functionality, which involves redox reactions, to the surface of the second electrode. Examples of radical polymerizable compounds having the triarylamine skeleton include compounds represented by the following general formula 5. [General formula 5] An-Bm However, when n=2, m is 0, and when n=1, m is 0 or 1. At least one of A and B has a radically polymerizable functional group. The structure of A is represented by the following general formula 6, and R1 to R 15 It is coupled to B at one of the following positions. B has the structure shown in the following general formula 7, and R 16 From R 21 It is connected to A at one of the positions. The radical polymerizable compound having a tetraarylbenzidine skeleton is one of the compounds represented by the general formula 5 above, with n=2. [General formula 6] [ka] [General formula 7] [ka] However, in the above general formulas 6 and 7, R1 to R 21 These are all monovalent groups, which may be the same or different, and at least one of the monovalent groups is a radically polymerizable functional group.

[0104] -A monovalent base- The monovalent group in general formulas 6 and 7 can be, for example, independently of each other, a hydrogen atom, a halogen atom, a hydroxyl group, a nitro group, a cyano group, a carboxyl group, an optionally substituted alkoxycarbonyl group, an optionally substituted aryloxycarbonyl group, an optionally substituted alkylcarbonyl group, an optionally substituted arylcarbonyl group, an amide group, an optionally substituted monoalkylaminocarbonyl group, an optionally substituted dialkylaminocarbonyl group, an optionally substituted monoarylaminocarbonyl group, an optionally substituted diarylaminocarbonyl group, a sulfonic acid group, an optionally substituted alkoxysulfonyl group, an optionally substituted aryloxysulfonyl group, an optionally substituted alkylsulfonyl group, or an optionally substituted group. Examples include arylsulfonyl groups, sulfonamide groups, optionally substituted monoalkylaminosulfonyl groups, optionally substituted dialkylaminosulfonyl groups, optionally substituted monoarylaminosulfonyl groups, optionally substituted diarylaminosulfonyl groups, amino groups, optionally substituted monoalkylamino groups, optionally substituted dialkylamino groups, optionally substituted alkyl groups, optionally substituted alkenyl groups, optionally substituted alkynyl groups, optionally substituted aryl groups, optionally substituted alkoxy groups, optionally substituted aralkyl groups, optionally substituted aryloxy groups, optionally substituted alkylthio groups, optionally substituted arylthio groups, and optionally substituted heterocyclic groups. Among these, alkyl groups, alkoxy groups, hydrogen atoms, aryl groups, aryloxy groups, halogen atoms, alkenyl groups, and alkynyl groups are particularly preferred from the viewpoint of stable operation.

[0105] Examples of halogen atoms include fluorine, chlorine, bromine, and iodine atoms. Examples of alkyl groups include methyl, ethyl, propyl, and butyl groups. Examples of aryl groups include phenyl and naphthyl groups. Examples of aralkyl groups include benzyl, phenethyl, and naphthylmethyl groups. Examples of alkoxy groups include methoxy, ethoxy, and propoxy groups. Examples of aryloxy groups include phenoxy, 1-naphthyloxy, 2-naphthyloxy, 4-methoxyphenoxy, and 4-methylphenoxy groups. Examples of heterocyclic groups include carbazole, dibenzofuran, dibenzothiophene, oxadiazole, and thiadiazole.

[0106] Examples of substituents that may be further substituted for the substituents include halogen atoms, alkyl groups such as nitro groups, cyano groups, methyl groups, and ethyl groups, alkoxy groups such as methoxy groups and ethoxy groups, aryloxy groups such as phenoxy groups, aryl groups such as phenyl groups and naphthyl groups, and aralkyl groups such as benzyl groups and phenethyl groups.

[0107] -Radical polymerizable functional group- The radical polymerizable functional group can be any group having a carbon-carbon double bond and capable of radical polymerization. Examples of the radical polymerizable functional group include the 1-substituted ethylene functional group and the 1,1-substituted ethylene functional group shown below.

[0108] (1) Examples of 1-substituted ethylene functional groups include the functional group represented by the following general formula (i). [ka] However, in the general formula (i) above, X1 is an optionally substituted arylene group, an optionally substituted alkenylene group, a -CO- group, a -COO- group, or a -CON(R 100 )-group [R 100represents a hydrogen atom, alkyl group, aralkyl group, or aryl group. ] or -S- group. Examples of the arylene group of general formula (i) include a phenylene group and a naphthylene group, which may have substituents. Examples of the alkenylene group include an etenylene group, a propenylene group, and a butenylene group. Examples of the alkyl group include a methyl group and an ethyl group. Examples of the aralkyl group include a benzyl group, a naphthylmethyl group, and a phenethyl group. Examples of the aryl group include a phenyl group and a naphthyl group. Specific examples of the radical polymerizable functional group represented by the general formula (i) above include vinyl group, styryl group, 2-methyl-1,3-butadienyl group, vinylcarbonyl group, acryloyl group, acryloyloxy group, acryloylamide group, vinylthioether group, and the like.

[0109] (2) Examples of 1,1-substituted ethylene functional groups include the functional group represented by the following general formula (ii). [ka] However, in the general formula (ii) above, Y is an optionally substituted alkyl group, an optionally substituted aralkyl group, an optionally substituted aryl group, a halogen atom, a cyano group, a nitro group, an alkoxy group, or a -COOR group. 101 Group [R 101 This is a hydrogen atom, an optionally substituted alkyl group, an optionally substituted aralkyl group, an optionally substituted aryl group, or CONR 102 R 103 (R 102 and R 103 X1 represents a hydrogen atom, an optionally substituted alkyl group, an optionally substituted aralkyl group, or an optionally substituted aryl group, and may be the same or different from each other. X2 represents the same substituent and single bond and alkylene group as X1 in the general formula (i) above. However, at least one of Y and X2 is an oxycarbonyl group, a cyano group, an alkenylene group, or an aromatic ring. Examples of the aryl group in the general formula (ii) include a phenyl group, a naphthyl group, etc. Examples of the alkyl group include a methyl group, an ethyl group, etc. Examples of the alkoxy group include a methoxy group, an ethoxy group, etc. Examples of the aralkyl group include a benzyl group, a naphthylmethyl group, a phenethyl group, etc.

[0110] Specific examples of the radically polymerizable functional group represented by the general formula (ii) include an α-chloroacryloyloxy group, a methacryloyl group, a methacryloyloxy group, an α-cyanoethylene group, an α-cyanoacryloyloxy group, an α-cyanophenylene group, a methacryloylamino group, etc.

[0111] Examples of the substituent that further substitutes the substituents for X1, X2, and Y include a halogen atom, a nitro group, a cyano group, an alkyl group such as a methyl group and an ethyl group, an alkoxy group such as a methoxy group and an ethoxy group, an aryloxy group such as a phenoxy group, an aryl group such as a phenyl group and a naphthyl group, an aralkyl group such as a benzyl group and a phenethyl group, etc.

[0112] Among these radically polymerizable functional groups, an acryloyloxy group and a methacryloyloxy group are particularly preferred.

[0113] Preferred examples of the radically polymerizable compound having a triarylamine skeleton include compounds represented by the following general formulas (2-1) to (2-3). [General formula (2-1)] [Chemical formula] [General formula (2-2)] [Chemical formula] [General formula (2-3)] [Chemical formula] In the general formulas (2-1) to (2-3), R 27From R 89 R are all monovalent groups, which may be the same or different from each other, and at least one of the monovalent groups is a radically polymerizable functional group. Examples of the monovalent group and the radically polymerizable functional group include those same as the general formula 5. Among these, the compound represented by the general formula (2-1) is a radically polymerizable compound having the tetraarylbenzidine skeleton. Examples of the general formula 5 and the exemplified compounds represented by the general formulas (2-1) to (2-3) include, for example, those shown below. The radically polymerizable compound having the triarylamine skeleton and the radically polymerizable compound having the tetraarylbenzidine skeleton are not limited to these.

[0114] <Exemplified Compound 3-1>

Chemical Formula

Chemical Formula

Chemical Formula

Chemical Formula

Chemical Formula

Chemical Formula

Chemical Formula

Chemical Formula

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Chem.

Chem.

Chem.

Chem.

Chem.

Chem.

Chem.

Chem.

Chem.

Chem.

Chem.

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[0115] <<Other polymerizable compounds>> The polymerizable material for forming the second electrochromic layer may contain other polymerizable compounds as needed.

[0116] The aforementioned other radical polymerizable compounds are different from the radical polymerizable compounds having the triarylamine skeleton. Furthermore, the aforementioned other radical polymerizable compounds are compounds having at least one radical polymerizable functional group. Examples of the aforementioned other radical polymerizable compounds include monofunctional radical polymerizable compounds, difunctional radical polymerizable compounds, trifunctional or more radical polymerizable compounds, functional monomers, and radical polymerizable oligomers. Among these, difunctional or more radical polymerizable compounds are particularly preferred. The radical polymerizable functional group in the aforementioned other radical polymerizable compounds is the same as the radical polymerizable functional group in the radical polymerizable compounds having the triarylamine skeleton, and among these, acryloyloxy groups and methacryloyloxy groups are particularly preferred.

[0117] Examples of the monofunctional radical polymerizable compounds include 2-(2-ethoxyethoxy)ethyl acrylate, methoxypolyethylene glycol monoacrylate, methoxypolyethylene glycol monomethacrylate, phenoxypolyethylene glycol acrylate, 2-acryloyloxyethyl succinate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, tetrahydrofurfuryl acrylate, 2-ethylhexyl carbitol acrylate, 3-methoxybutyl acrylate, benzyl acrylate, cyclohexyl acrylate, isoamyl acrylate, isobutyl acrylate, methoxytriethylene glycol acrylate, phenoxytetraethylene glycol acrylate, cetyl acrylate, isostearyl acrylate, stearyl acrylate, and styrene monomer. These may be used individually or in combination of two or more.

[0118] Examples of the aforementioned bifunctional radical polymerizable compounds include 1,3-butanediol diacrylate, 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, diethylene glycol diacrylate, polyethylene glycol diacrylate, neopentyl glycol diacrylate, EO-modified bisphenol A diacrylate, EO-modified bisphenol F diacrylate, and neopentyl glycol diacrylate. These may be used individually or in combination of two or more.

[0119] Examples of the three- or more-functional radical polymerizable compounds include trimethylolpropane triacrylate (TMPTA), trimethylolpropane trimethacrylate, EO-modified trimethylolpropane triacrylate, PO-modified trimethylolpropane triacrylate, caprolactone-modified trimethylolpropane triacrylate, HPA-modified trimethylolpropane trimethacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate (PETTA), glycerol triacrylate, ECH-modified glycerol triacrylate, EO-modified glycerol triacrylate, PO-modified glycerol triacrylate, and Examples include ris(acryloxyethyl) isocyanurate, dipentaerythritol hexaacrylate (DPHA), caprolactone-modified dipentaerythritol hexaacrylate, dipentaerythritol hydroxypentaacrylate, alkyl-modified dipentaerythritol pentaacrylate, alkyl-modified dipentaerythritol tetraacrylate, alkyl-modified dipentaerythritol triacrylate, dimethylolpropane tetraacrylate (DTMPTA), pentaerythritol ethoxytetraacrylate, EO-modified phosphate triacrylate, and 2,2,5,5-tetrahydroxymethylcyclopentanone tetraacrylate. These may be used individually or in combination of two or more. In the above, EO-modified refers to ethylene-oxy modified, and PO-modified refers to propylene-oxy modified.

[0120] Examples of the functional monomers include fluorine-substituted monomers such as octafluoropentyl acrylate, 2-perfluorooctylethyl acrylate, 2-perfluorooctylethyl methacrylate, and 2-perfluoroisononylethyl acrylate; vinyl monomers having polysiloxane groups, such as acryloyl polydimethylsiloxane ethyl, methacryloyl polydimethylsiloxane ethyl, acryloyl polydimethylsiloxane propyl, acryloyl polydimethylsiloxane butyl, and diacryloyl polydimethylsiloxane diethyl, as described in Japanese Patent Publication No. 5-60503 and Japanese Patent Publication No. 6-45770, which have 20 to 70 siloxane repeating units; acrylates; and methacrylates. These may be used individually or in combination of two or more.

[0121] Examples of the radical polymerizable oligomers include epoxy acrylate oligomers, urethane acrylate oligomers, and polyester acrylate oligomers.

[0122] It is preferable, from the standpoint of forming a crosslinked product, that at least one of the radical polymerizable compound having the triarylamine skeleton and another radical polymerizable compound different from the aforementioned radical polymerizable compound having the triarylamine skeleton has two or more radical polymerizable functional groups.

[0123] The content of the radical polymerizable compound having the triarylamine skeleton is preferably 10% to 100% by mass, and more preferably 30% to 90% by mass, relative to the total amount of material exhibiting electrochromic function in the polymerizable material. When the content is 10% by mass or more, the electrochromic function of the second electrochromic layer can be sufficiently expressed, resulting in good durability with repeated use under applied voltage and good color sensitivity. Electrochromic function is also possible with a content of 100% by mass, in which case the color sensitivity with respect to thickness is highest. Conversely, the compatibility with ions necessary for charge transfer may be low, leading to deterioration of electrical properties such as reduced durability with repeated use under applied voltage. Although it is not possible to generalize as the required electrical properties differ depending on the process used, considering the balance between color sensitivity and repeated durability, 30% to 90% by mass is particularly preferred.

[0124] <<Polymerization initiator>> The polymerizable material may contain a polymerization initiator (e.g., a radical polymerization initiator) as needed to efficiently carry out the polymerization reaction of the radical polymerizable compound having the triarylamine skeleton. Examples of polymerization initiators include thermal polymerization initiators and photopolymerization initiators, but photopolymerization initiators are preferred from the viewpoint of polymerization efficiency.

[0125] There are no particular restrictions on the thermal polymerization initiator, and it can be appropriately selected depending on the purpose. Examples include peroxide-based initiators such as 2,5-dimethylhexane-2,5-dihydroperoxide, dicumyl peroxide, benzoyl peroxide, t-butylcumyl peroxide, 2,5-dimethyl-2,5-di(peroxybenzoyl)hexine-3, di-t-butylperoxide, t-butylhydroperoxide, cumenehydroperoxide, and lauroyl peroxide; and azo-based initiators such as azobisisobutylnitrile, azobiscyclohexanecarbonitride, azobisisobutyrate methyl, azobisisobutylamidine hydrochloride, and 4,4'-azobis-4-cyanovaleric acid. These may be used individually or in combination of two or more.

[0126] The aforementioned photopolymerization initiator is not particularly limited and can be appropriately selected depending on the purpose. Examples include acetophenone-based or ketal-based photopolymerization initiators such as diethoxyacetophenone, 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxycyclohexylphenyl-ketone, 4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone-1, 2-hydroxy-2-methyl-1-phenylpropane-1-one, 2-methyl-2-morpholino(4-methylthiophenyl)propane-1-one, and 1-phenyl-1,2-propanedione-2-(o-ethoxycarbonyl)oxime. Polymerization initiators include: benzoin ether-based photopolymerization initiators such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isobutyl ether, and benzoin isopropyl ether; benzophenone-based photopolymerization initiators such as benzophenone, 4-hydroxybenzophenone, o-benzoyl methyl benzoate, 2-benzoylnaphthalene, 4-benzoylbiphenyl, 4-benzoylphenyl ether, acrylic benzophenone, and 1,4-benzoylbenzene; and thioxanthone-based photopolymerization initiators such as 2-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, and 2,4-dichlorothioxanthone.

[0127] Other photopolymerization initiators include, for example, ethylanthraquinone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylethoxyphosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, bis(2,4-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, methylphenylglyoxyester, 9,10-phenanthrene, acridine compounds, triazine compounds, and imidazole compounds. These may be used individually or in combination of two or more.

[0128] In addition, those having a photopolymerization promoting effect can be used alone or in combination with the photopolymerization initiator. For example, triethanolamine, methyldiethanolamine, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, (2-dimethylamino)ethyl benzoate, 4,4'-dimethylaminobenzophenone, etc. can be mentioned.

[0129] When forming the second electrochromic layer, the content of the polymerization initiator in the polymerizable material is preferably 0.5 parts by mass or more and 40 parts by mass or less, more preferably 1 part by mass or more and 20 parts by mass or less, based on 100 parts by mass of the total amount of the radical polymerizable compound. Here, the radical polymerizable compound refers to the total amount of the radical polymerizable compounds contained in the polymerizable material.

[0130] <Electrolyte layer> The electrolyte layer contains at least an electrolyte.

[0131] <<Electrolyte>> The electrolyte is not particularly limited and known ones can be used. However, it is preferable that the anion of the electrolyte is a monovalent anion having an oxidation potential 3.1 V or higher than the reduction potential of the dication in the general formula 1. Examples of such anions include (FSO2)2N - , (CF3SO2)2N - , (CN)4B - , BF4 - , CF3BF3 - , PF6 - , ClO4 - , (C2F5SO2)2N - , (C4F9SO2)2N - , CF3SO3, C2F5SO3, C4F9SO3, (C2F5)3PF3 - , (CF3SO2)3C -These are some examples. By using electrolytes with these anions, even when ion exchange occurs between the anions of the electrochromic compound and the anions of the electrolyte within the device, discoloration due to CT transitions of the electrochromic compound can be prevented, thus enabling the creation of electrochromic devices with superior transparency.

[0132] More preferably, the anion of the electrolyte is (FSO2)2N - (CF3SO2)2N - (CN)4B - BF4 - PF6 - ClO4 - This is the case. These anions can prevent discoloration due to CT transitions of the electrochromic compound even when ion exchange occurs between the anions of the electrochromic compound and the anions of the electrolyte within the device. Furthermore, they are stable and not too large to obtain a sufficient response speed. Therefore, by using these anions, it is possible to obtain a device that is not only highly transparent but also highly responsive.

[0133] The electrolyte cation is not particularly limited, and examples of electrolytes include metal ion systems such as Li salts, Na salts, K salts, and Mg salts; imidazole derivatives such as N,N-dimethylimidazole salt, N,N-methylethylimidazole salt, N,N-methylpropylimidazole salt, N,N-methylbutylimidazole salt, and N,N-allylbutylimidazole salt; pyridinium derivatives such as N,N-dimethylpyridinium salt and N,N-methylpropylpyridinium salt; pyrrolidinium derivatives such as N,N-dimethylpyrrolidinium salt, N-ethyl-N-methylpyrrolidinium salt, N-methyl-N-propylpyrrolidinium salt, N-butyl-N-methylpyrrolidinium salt, N-methyl-N-pentylpyrrolidinium salt, and N-hexyl-N-methylpyrrolidinium salt; and aliphatic quaternary ammonium systems such as trimethylpropylammonium salt, trimethylhexylammonium salt, and triethylhexylammonium salt.

[0134] The aforementioned anions and cations can be used in any combination; they may be used individually or in combination of multiple types.

[0135] In particular, combinations of anions and cations whose electrolyte melting point is below room temperature are preferred. That is, it is preferable to use an ionic liquid as the electrolyte. Furthermore, organic ionic liquids are preferred because they have a molecular structure that exhibits liquid behavior over a wide temperature range, including room temperature.

[0136] The electrolyte may be directly dissolved in a photopolymerizable monomer, oligomer, or liquid crystal material. If solubility is poor, it may be dissolved in a small amount of solvent and then mixed with the photopolymerizable monomer, oligomer, or liquid crystal material before use.

[0137] Examples of the aforementioned solvents include propylene carbonate, acetonitrile, γ-butyrolactone, ethylene carbonate, sulfolane, dioxolane, tetrahydrofuran, 2-methyltetrahydrofuran, dimethyl sulfoxide, 1,2-dimethoxyethane, 1,2-ethoxymethoxyethane, polyethylene glycol, alcohols, or mixtures thereof.

[0138] The electrolyte layer does not need to be a low-viscosity liquid; it can take various forms such as a gel, polymer crosslinked, or liquid crystal dispersion. Forming the electrolyte into a gel or solid state offers advantages such as improved device strength and reliability.

[0139] As a solidification method, it is preferable to retain the electrolyte within the polymer resin. This is because it allows for high ionic conductivity and solid strength to be obtained.

[0140] Furthermore, a photocurable resin is preferred as the polymer resin. This is because it allows for the manufacture of devices at low temperatures and in a short time compared to methods of thin-film formation by thermal polymerization or evaporation of solvents. The average thickness of the electrolyte layer, which consists of the aforementioned electrolyte, is not particularly limited and can be appropriately selected depending on the purpose, but it is preferably 100 nm or more and 100 μm or less. The average thickness of the electrolyte layer is not particularly limited and can be appropriately selected depending on the purpose, but it is preferably 0.1 times or more and 1000 times or less the average thickness of the first electrochromic layer.

[0141] <First electrode and second electrode> The materials for the first and second electrodes are not particularly limited and can be any commonly used conductors. The transparent electrode is not particularly limited as long as it is a transparent material that has conductivity, and can be appropriately selected according to the purpose. Examples include tin-doped indium oxide (hereinafter referred to as "ITO"), fluorine-doped tin oxide, antimony-doped tin oxide, zinc oxide, and other inorganic materials. Among these, InSnO, GaZnO, SnO, In2O3, and ZnO are preferred. Furthermore, electrodes may be used in which transparent carbon nanotubes or other highly conductive, impermeable materials such as Au, Ag, Pt, and Cu are formed in a fine network to improve conductivity while maintaining transparency. The thickness of the first electrode and the second electrode are adjusted to obtain the electrical resistance value necessary for the oxidation-reduction reaction of the electrochromic layer. When ITO is used as the material for the first electrode and the second electrode, the thickness of each of the first electrode and the second electrode is preferably, for example, 50 nm or more and 500 nm or less.

[0142] As methods for fabricating the first electrode and the second electrode, vacuum deposition, sputtering, ion plating, and the like can be used. There are no particular restrictions on the materials of the first electrode and the second electrode, as long as they can be coated and formed. For example, various printing methods such as spin coating, casting, microgravure coating, gravure coating, bar coating, roll coating, wire bar coating, dip coating, slit coating, capillary coating, spray coating, nozzle coating, gravure printing, screen printing, flexographic printing, offset printing, reverse printing, and inkjet printing can be used.

[0143] <Other components> The electrochromic element of the present invention may further include other components as needed. The aforementioned other components are not particularly limited and can be appropriately selected according to the purpose, and examples include support materials, sealing materials, protective layers, etc.

[0144] <<Support>> As a support, any transparent material capable of supporting each layer can be used, including well-known organic and inorganic materials. As the support, for example, a glass substrate such as alkali-free glass, borosilicate glass, float glass, or soda-lime glass can be used. Alternatively, a resin substrate such as polycarbonate resin, acrylic resin, polyethylene, polyvinyl chloride, polyester, epoxy resin, melamine resin, phenolic resin, polyurethane resin, or polyimide resin may be used as the support. Furthermore, the surface of the support may be coated with a transparent insulating layer, a UV-cutting layer, an anti-reflective layer, etc., to enhance water vapor barrier properties, gas barrier properties, ultraviolet resistance, and visibility. The shape of the support may be rectangular or round, and is not particularly limited. The support may consist of multiple layers; for example, by sandwiching an electrochromic element between two glass substrates, it is possible to enhance water vapor barrier properties and gas barrier properties.

[0145] <<Sealant>> The encapsulant has functions such as sealing the sides of the bonded electrochromic elements to prevent electrolyte leakage and preventing the intrusion of unwanted substances such as moisture and oxygen from the atmosphere that are necessary for the stable operation of the electrochromic elements. The encapsulant is not particularly limited, and for example, UV-curing or thermosetting resins can be used, specifically acrylic, urethane, and epoxy resins.

[0146] <<Protective layer>> The protective layer's role includes protecting the element from external stresses and chemicals used in the cleaning process, preventing electrolyte leakage, and preventing the intrusion of substances unnecessary for the stable operation of the electrochromic element, such as moisture and oxygen from the atmosphere. There are no particular restrictions on the thickness of the protective layer, and it can be appropriately selected depending on the purpose, but a thickness of 1 μm or more and 200 μm or less is preferred. As the material for the protective layer, for example, UV-curing or thermosetting resins can be used, and specifically, acrylic, urethane, and epoxy resins are examples of such materials.

[0147] <Application> Because the electrochromic element of the present invention has excellent transparency, it can be suitably used in, for example, electrochromic devices, electrochromic displays, large display boards such as stock price display boards, dimming elements such as anti-glare mirrors, dimming glass, dimming lenses, and dimming films, low-voltage driving elements such as touch panel key switches, optical switches, optical memory, electronic paper, and electronic albums. [Examples]

[0148] The following describes examples of the present invention, but the present invention is not limited in any way to the following examples.

[0149] <Measurement of the reduction potential of dications> Octyl viologen dibromide (Tokyo Chemical) was dissolved in propylene carbonate to a concentration of 0.01 mol / L, and 1-ethyl-3-methyl-imidazolium bis(fluorosulfonyl)imide (EMIMFSI, Kanto Chemical) was further dissolved as an electrolyte to a concentration of 0.1 mol / L to prepare the measurement solution. A glassy carbon electrode was used as the working electrode, a platinum electrode as the counter electrode, and an Ag / Ag+ electrode separated by ion-permeable glass as the reference electrode. Cyclic voltammetry was performed using a potentiostat to measure the reduction potential of the octyl viologen dication. Note that the dications of example compounds 1-1 to 1-18 and 1-24 to 1-26, which have a common viologen skeleton, exhibit the same reduction potential. Furthermore, when example compounds 1-19 to 1-23 were dissolved in propylene carbonate to a concentration of 0.01 mol / L and the reduction potential of the dications was measured using the same method, the reduction potentials of each compound were all lower than that of the dication of octyl viologen.

[0150] <Measurement of the oxidation potential of anions> Next, 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide was dissolved in propylene carbonate at a concentration of 0.1 mol / L as the anion of example compound 1-1 and example compound 1-7, and the oxidation potential of the FSI anion was measured by sweeping the potential towards the oxidation side. As a result, no significant reaction current was observed even at a potential 3.1 V higher than the reduction potential of the octyl viologen dication. From this, it can be seen that the oxidation potential of the bis(fluorosulfonyl)imide anion is 3.1 V or more higher than the reduction potential of the dications of example compounds 1-1 to 1-26.

[0151] Similarly, 1-ethyl-3-methyl-imidazolium bis(trifluoromethanesulfonyl)imide was used as the anion for example compounds 1-2 and 1-8 to 1-34, 1-ethyl-3-methyl-imidazolium tetracyanoborate was used as the anion for example compound 1-3, 1-ethyl-3-methyl-imidazolium tetrafluoroborate was used as the anion for example compound 1-4, 1-butyl-3-methyl-imidazolium hexafluorophosphate was used as the anion for example compound 1-5, and tetrabutylammonium perchloride was used as the anion for example compound 1-6. These solutions were dissolved in propylene carbonate at a concentration of 0.1 mol / L, and the oxidation potential of each anion was measured by sweeping the potential towards the oxidation side. As a result, no significant reaction current was observed even at a potential 3.1V higher than the reduction potential of the octyl viologen dication. In all measurements, an oxidation current began to flow around a potential exceeding 3.1V higher than the reduction potential of the octyl viologen dication. Since it is unlikely that all anions have the same oxidation potential, this current is thought to be due to the oxidation of propylene carbonate. Therefore, the specific oxidation potential of each anion is unknown, but it is certainly at least 3.1V higher than the reduction potential of the octyl viologen dication. From this, it can be seen that the oxidation potential of these anions is at least 3.1V higher than the reduction potential of the dications of example compounds 1-1 to 1-26.

[0152] (Example 1) <Fabrication of electrochromic layer> A titanium dioxide nanoparticle dispersion (product name: SP210, manufactured by Showa Titanium Co., Ltd., average particle size: approximately 20 nm) was applied by spin coating onto an ITO glass substrate (40 mm x 40 mm, thickness 0.7 mm, ITO film thickness: approximately 100 nm) as the first electrode, and then annealed at 120°C for 15 minutes to form a nanostructured semiconductor material consisting of a titanium dioxide particle film with a thickness of 2.5 μm. A 40 mmol% 2,2,3,3-tetrafluoropropanol solution of Exemplary Compound 1-1 was applied to this titanium oxide particle film by spin coating, and an annealing treatment was performed at 120°C for 10 minutes to form a first electrochromic layer with a thickness of 2.5 μm on the first electrode, in which Exemplary Compound 1-1 was deposited on the surface of the titanium oxide particles.

[0153] <Fabrication of the second electrochromic layer> On an ITO glass substrate (40 mm × 40 mm, thickness 0.7 mm, ITO film thickness: approximately 100 nm) serving as the second electrode, a solution was prepared by mixing exemplary compound 3-10 having a triarylamine skeleton and exemplary compound 3-40 having a tetraarylbenzidine skeleton as the second electrochromic compound, Bremmer AME400 (NOF) and Bremmer ADE400A (NOF) as other polymerizable compounds, Irgacure 184 as a polymerization initiator, and 2-butanone as a solvent in a mass ratio (exemplary compound 3-10:exemplary compound 3-40:AME400:ADE400A:irgacure 184:2-butanone = 3:7:6:4:0.1:80). This solution was applied and dried by spin coating, and then UV-cured under a nitrogen atmosphere to form a second electrochromic layer with a thickness of 1.3 μm on the second electrode.

[0154] <Electrolyte filling> First, 195 parts by mass of Bremmer AME400 (NOF) and 195 parts by mass of Bremmer ADE400A (NOF) were mixed as monomers, 10 parts by mass of IRGACURE184 (BASF) as a polymerization initiator, and 60 parts by mass of 1-ethyl-3-methyl-imidazolium bis(fluorosulfonyl)imide (EMIMFSI, Kanto Chemical) as an electrolyte to obtain a monomer composition solution and an electrolyte solution. 50 μL of the obtained electrolyte solution was measured using a micropipette and dropped onto an ITO glass substrate having the first electrochromic layer. An ITO glass substrate having a second electrochromic layer was then bonded to it, with an electrode lead-out portion, to fabricate a bonded element. The resulting bonded element was irradiated with UV (wavelength 250 nm) light (SPOT CURE, manufactured by Ushio Inc.) at 10 mW for 60 seconds. An electrochromic element was then fabricated. The average thickness of the electrolyte layer was 30 μm.

[0155] <Evaluation of colorless and transparent properties> The transmittance of the fabricated electrochromic elements was measured using an Ocean Optics USB4000, and the yellow index (YI) value was calculated from the obtained spectra. The calculation results are shown in Table 1-1.

[0156] <Color intensity evaluation> For the fabricated electrochromic element, the color-producing area was 10 mC / cm² per unit area. 2 The transmittance at 610 nm when a charge was applied was measured using an Ocean Optics USB4000. The measurement results are shown in Table 1-1.

[0157] <Durability Evaluation> For the fabricated electrochromic element, the color-producing area was 5 mC / cm² per unit area. 2 The sample was subjected to a charge to induce color development and then tested in a weather resistance tester SUNTEST CPS+ (Toyo Seiki) at an ambient temperature of 28°C and a light intensity of 250 W / m². 2 A 50-hour durability test was conducted. After the test, the element was decolorized, and its transmittance was measured using an Ocean Optics USB4000. The yellow index (YI) value was calculated from the obtained spectrum. The yellow index value was calculated using the same method as the evaluation of colorless transparency described above. The increase in YI from the value before the durability test, ΔYI, was calculated. The calculation results are shown in Table 1-1.

[0158] (Examples 2-90) Regarding the fabrication method of the electrochromic elements, electrochromic elements were fabricated and evaluated in the same manner as in Example 1, except that the electrochromic compounds and electrolytes were changed to those shown in Tables 1-1 to 1-4. The results are shown in Tables 1-1 to 1-4. The notation for the electrolytes is summarized in Table 2.

[0159] (Comparative Examples 1-3) Regarding the fabrication method of the electrochromic elements, electrochromic elements were fabricated and evaluated in the same manner as in Example 1, except that the electrochromic compounds and electrolytes were changed to those shown in Table 1-4. The results are shown in Table 1-4. The electrochromic compounds used in the comparative examples are the compounds listed below. <Comparative compound 1> [ka] <Comparative compound 2> [ka] <Comparative compound 3> [ka]

[0160] <Measurement of the oxidation potential of the anion in the comparative example> Similar to the method for measuring the oxidation potential of anions of electrochromic compounds according to the present invention, the oxidation potentials of 1-ethyl-3-methyl-imidazolium bromide were measured as the anion of comparative compound 1 and comparative compound 3, and the oxidation potential of 1-ethyl-3-methyl-imidazolium chloride was measured as the anion of comparative compound 2. As a result, a current due to the oxidation reaction was confirmed for 1-ethyl-3-methyl-imidazolium bromide at a potential 1.1V higher than the reduction potential of the dication of octyl viologen, and a current due to the oxidation reaction was confirmed for 1-ethyl-3-methyl-imidazolium chloride at a potential 1.4V higher than the reduction potential of viologen. From this, it can be seen that the oxidation potentials of these anions are not more than 3.1V higher than the reduction potential of the dications of comparative compounds 1 to 3.

[0161] [Table 1-1]

[0162] [Table 1-2]

[0163] [Table 1-3]

[0164] [Table 1-4]

[0165] [Table 2]

[0166] The results confirmed that the electrochromic element of the present invention exhibits excellent transparency, color density, and durability.

[0167] Examples of the present invention are as follows: <1> The first electrode and A second electrode is provided opposite to the first electrode at a distance from it, A first electrochromic layer having a conductive or semiconducting nanostructure and an electrochromic compound is provided on the first electrode. The first electrochromic layer and the second electrode are separated by an electrolyte layer containing an electrolyte, The electrochromic compound is a compound represented by the following general formula 1, The electrochromic element is characterized in that the anion of the electrolyte is a monovalent anion having an oxidation potential 3.1V or higher than the reduction potential of the dication in the general formula 1. [General formula 1] [ka] In the above general formula 1, R1 and R2 each represent a functional group that can be bonded to a hydrogen atom, an aryl group having up to 14 carbon atoms, a heteroaryl group having up to 14 carbon atoms, a branched alkyl group having up to 10 carbon atoms, an alkenyl group having up to 10 carbon atoms, or a cycloalkyl group having up to 10 carbon atoms, or a hydroxyl group. R3 and R4 each represent an alkylene group having 1 to 10 carbon atoms or an arylene group having up to 12 carbon atoms which may have substituents. In the above general formula 1, Z is selected from the divalent groups of alkylene, cycloalkylene, and R7-Y-R8 (wherein R7 and R8 are each independently selected from a single bond, alkylene, and cycloalkylene, and Y is selected from arylene, cycloalkylene, heteroarylene, arylene-arylene, and arylene-CR'R''-arylene, where R' and R'' form a carbocyclic group together with the carbon to which they are bonded). The alkylene, cycloalkylene, arylene, heteroarylene, and carbocyclic group may be substituted with one or more substituents selected from halogen, alkyl, alkoxy, alkylthio, hydroxyalkyl, acyloxy, cycloalkyl, aryl, substituted aryl, aryloxy, heteroaryl, and substituted heteroaryl. k represents 0 or 1. In the general formula 1, X - This represents a monovalent anion having an oxidation potential at least 3.1 V higher than the reduction potential of the dication in the general formula 1. In the above general formula 1, W 2+ This represents a dication represented by the following general formula 2. [General formula 2] [ka] In the above general formula 2, o, p, and q each independently represent 0 or 1, and A, B, and C each independently represent an arylene group or heterocyclic group having 2 to 20 carbon atoms, which may have substituents. <2> The first electrochromic layer is obtained by attaching the electrochromic compound to the nanostructure, <1> This is the electrochromic element described in [reference]. <3> The first electrode and A second electrode is provided opposite to the first electrode at a distance from it, On the first electrode, a first electrochromic layer is provided, which is obtained by depositing an electrochromic compound onto a conductive or semiconducting nanostructure. The first electrochromic layer and the second electrode are separated by an electrolyte layer. The electrochromic element is characterized in that the electrochromic compound is a compound represented by the following general formula 1. [General formula 1] [ka] In the above general formula 1, R1 and R2 each represent a functional group that can be bonded to a hydrogen atom, an aryl group having up to 14 carbon atoms, a heteroaryl group having up to 14 carbon atoms, a branched alkyl group having up to 10 carbon atoms, an alkenyl group having up to 10 carbon atoms, or a cycloalkyl group having up to 10 carbon atoms, or a hydroxyl group. R3 and R4 each represent an alkylene group having 1 to 10 carbon atoms or an arylene group having up to 12 carbon atoms which may have substituents. In the above general formula 1, Z is selected from the divalent groups of alkylene, cycloalkylene, and R7-Y-R8 (wherein R7 and R8 are each independently selected from a single bond, alkylene, and cycloalkylene, and Y is selected from arylene, cycloalkylene, heteroarylene, arylene-arylene, and arylene-CR'R''-arylene, where R' and R'' form a carbocyclic group together with the carbon to which they are bonded). The alkylene, cycloalkylene, arylene, heteroarylene, and carbocyclic group may be substituted with one or more substituents selected from halogen, alkyl, alkoxy, alkylthio, hydroxyalkyl, acyloxy, cycloalkyl, aryl, substituted aryl, aryloxy, heteroaryl, and substituted heteroaryl. k represents 0 or 1. In the general formula 1, X - This represents a monovalent anion having an oxidation potential at least 3.1 V higher than the reduction potential of the dication in the general formula 1. In the above general formula 1, W 2+ This represents a dication represented by the following general formula 2. [General formula 2] [ka] In the above general formula 2, o, p, and q each independently represent 0 or 1, and A, B, and C each independently represent an arylene group or heterocyclic group having 2 to 20 carbon atoms, which may have substituents. <4> The electrolyte layer contains an electrolyte, The anion of the electrolyte is a monovalent anion having an oxidation potential 3.1 V or higher than the reduction potential of the dication in the general formula 1. <3> This is the electrochromic element described in [reference]. <5> The anion of the electrolyte in the electrolyte layer is (FSO2)2N - (CF3SO2)2N - (CN)4B - BF4 - PF6 - , and ClO4 -The above is one or more types selected from <1> , <2> , and <4> One of these is an electrochromic element. <6> In the above general formula 1, at least one of R1 and R2 is one of a phosphonic acid group, a phosphoric acid group, a carboxylic acid group, a sulfonyl group, a silyl group, and a silanol group. <1> from <5> It is an electrochromic element as described in any of the following. <7> In the above general formula 1, either R1 or R2 is one of a phosphonic acid group, a phosphoric acid group, a carboxylic acid group, a sulfonyl group, a silyl group, and a silanol group. The other party is one of a hydrogen atom, an aryl group having up to 14 carbon atoms, a heteroaryl group having up to 14 carbon atoms, a branched alkyl group having up to 10 carbon atoms, an alkenyl group having up to 10 carbon atoms, and a cycloalkyl group having up to 10 carbon atoms. <1> from <6> It is an electrochromic element as described in any of the following. <8> In the above general formula 1, X - However, (FSO2)2N - (CF3SO2)2N - (CN)4B - BF4 - PF6 - , and ClO4 - The above is one or more types selected from <1> from <7> It is an electrochromic element as described in any of the following. <9> In the above general formula 1, X - However, (FSO2)2N - , and (CF3SO2)2N - The above is one or more types selected from <1> from <8> It is an electrochromic element as described in any of the following. <10> In the above general formula 1, X - However, (CF3SO2)2N - The above <1> from <9> It is an electrochromic element as described in any of the following. <11> In the above general formula 1, W 2+ However, the above is represented by the following structural formula 1. <1> from <10> It is an electrochromic element as described in any of the following. [Structural formula 1] [ka] <12> In the above general formula 1, k is 0. <1> from <11> It is an electrochromic element as described in any of the following. <13> In the aforementioned general formula 1, R3 is represented by the following general formula 3, and R4 is represented by the following general formula 4. <1> from <12> It is an electrochromic element as described in any of the following. [General formula 3] [ka] [General formula 4] [ka] However, in the general formula 3, m represents an integer from 0 to 10, and in the general formula 4, n represents an integer from 0 to 10, and m and n may be the same value or different values. <14> The second electrode further has a second electrochromic layer, The electrolyte layer is located between the first electrochromic layer and the second electrochromic layer. <1> from <13> It is an electrochromic element as described in any of the following. <15> The second electrochromic layer contains a polymer obtained by polymerizing a polymerizable material that contains a radical polymerizable compound having a triarylamine skeleton. <14> This is the electrochromic element described in [reference]. <16> The polymerizable material further contains a radical polymerizable compound having a tetraarylbenzidine skeleton. <15> This is the electrochromic element described in [reference].

[0168] The aforementioned <1> from <16> The electrochromic element described above can solve the aforementioned problems of the conventional invention and achieve the objectives of the present invention. [Explanation of symbols]

[0169] 100 Electrochromic elements 101 First electrode 102 Second electrode 103 Electrolyte layer 104 First electrochromic layer 105 Second electrochromic layer [Prior art documents] [Patent Documents]

[0170] [Patent Document 1] Japanese Patent Publication No. 2017-107153 [Patent Document 2] Japanese Patent Publication No. 2008-052172 [Patent Document 3] Special Publication No. 2018-508034 [Patent Document 4] Japanese Patent Publication No. 2017-206499 [Patent Document 5] Patent No. 6456964 [Patent Document 6] Special Publication No. 2002-524762

Claims

1. The first electrode and A second electrode is provided opposite to the first electrode at a distance from it, A first electrochromic layer having a conductive or semiconducting nanostructure and an electrochromic compound is provided on the first electrode. The first electrochromic layer and the second electrode are separated by an electrolyte layer containing an electrolyte, The electrochromic compound is a compound represented by the following general formula 1, An electrochromic element characterized in that the anion of the electrolyte is a monovalent anion having an oxidation potential 3.1 V or higher than the reduction potential of the dication in the general formula 1. [General formula 1] 【Chemistry 1】 In the above general formula 1, R １ , and R ２ Each represents a functional group that can be bonded to a hydrogen atom, an aryl group up to 14 carbon atoms, a heteroaryl group up to 14 carbon atoms, a branched alkyl group up to 10 carbon atoms, an alkenyl group up to 10 carbon atoms, or a cycloalkyl group up to 10 carbon atoms, or a hydroxyl group, and at least one of R1 and R2 is one of a phosphonic acid group, a phosphoric acid group, a carboxylic acid group, a sulfonyl group, a silyl group, or a silanol group. ３ , and R ４ This represents an alkylene group having 1 to 10 carbon atoms. In the above general formula 1, Z is alkylene, cycloalkylene, and R ７ -Y-R ８ (Here, R ７ and R ８ Each of the following is independently selected from single bonds, alkylenes, and cycloalkylenes, and Y is selected from arylenes, cycloalkylenes, heteroarylenes, arylene-arylenes, and arylene-CR'R''-arylenes, where R' and R'' are divalent groups that form a carbocyclic group together with the carbon to which they are bonded. The alkylenes, cycloalkylenes, arylenes, heteroarylenes, and carbocyclic groups may be substituted with one or more substituents selected from halogens, alkyls, alkoxys, alkylthios, hydroxyalkyls, acyloxys, cycloalkyls, aryls, substituted aryls, aryloxys, heteroaryls, and substituted heteroaryls. k represents 0 or 1. In the general formula 1, X － represents a monovalent anion having an oxidation potential 3.1 V or more higher than the reduction potential of the dication in the general formula 1. In the above general formula 1, W ２＋ This represents a dication represented by the following general formula 2. [General formula 2] 【Chemistry 2】 In the above general formula 2, o, p, and q each independently represent 0 or 1, and A, B, and C each independently represent an arylene group or heterocyclic group having 2 to 20 carbon atoms, which may have substituents.

2. The electrochromic element according to claim 1, wherein the first electrochromic layer is obtained by attaching the electrochromic compound to the nanostructure.

3. The first electrode and A second electrode is provided opposite to the first electrode at a distance from it, On the first electrode, a first electrochromic layer is provided, which is obtained by attaching an electrochromic compound to a conductive or semiconducting nanostructure. The first electrochromic layer and the second electrode are separated by an electrolyte layer. An electrochromic element characterized in that the electrochromic compound is a compound represented by the following general formula 1. [General formula 1] 【Transformation 3】 In the above general formula 1, R １ , and R ２ Each represents a functional group that can be bonded to a hydrogen atom, an aryl group up to 14 carbon atoms, a heteroaryl group up to 14 carbon atoms, a branched alkyl group up to 10 carbon atoms, an alkenyl group up to 10 carbon atoms, or a cycloalkyl group up to 10 carbon atoms, or a hydroxyl group, and at least one of R1 and R2 is one of a phosphonic acid group, a phosphoric acid group, a carboxylic acid group, a sulfonyl group, a silyl group, or a silanol group. ３ , and R ４ This represents an alkylene group having 1 to 10 carbon atoms. In the above general formula 1, Z is alkylene, cycloalkylene, and R ７ -Y-R ８ (Here, R ７ and R ８ Each of the following is independently selected from single bonds, alkylenes, and cycloalkylenes, and Y is selected from arylenes, cycloalkylenes, heteroarylenes, arylene-arylenes, and arylene-CR'R''-arylenes, where R' and R'' are divalent groups that form a carbocyclic group together with the carbon to which they are bonded. The alkylenes, cycloalkylenes, arylenes, heteroarylenes, and carbocyclic groups may be substituted with one or more substituents selected from halogens, alkyls, alkoxys, alkylthios, hydroxyalkyls, acyloxys, cycloalkyls, aryls, substituted aryls, aryloxys, heteroaryls, and substituted heteroaryls. k represents 0 or 1. In the general formula 1, X － This represents a monovalent anion having an oxidation potential 3.1 V or higher than the reduction potential of the dication in the general formula 1. In the above general formula 1, W ２＋ This represents a dication represented by the following general formula 2. [General formula 2] 【Chemistry 4】 In the above general formula 2, o, p, and q each independently represent 0 or 1, and A, B, and C each independently represent an arylene group or heterocyclic group having 2 to 20 carbon atoms, which may have substituents.

4. The electrolyte layer contains an electrolyte, The electrochromic element according to claim 3, wherein the anion of the electrolyte is a monovalent anion having an oxidation potential 3.1 V or higher than the reduction potential of the dication in the general formula 1.

5. The anions of the electrolyte in the electrolyte layer are (FSO ２ ) ２ N － (CF ３ SO ２ ) ２ N － (CN) ４ B － BF ４ － , PF ６ － , and ClO ４ － An electrochromic element according to any one of claims 1, 2, and 4, which is one or more selected from the above.

6. In the above general formula 1, R １ and R ２ Either one of them is a phosphonic acid group, a phosphate group, a carboxylic acid group, a sulfonyl group, a silyl group, or a silanol group. The electrochromic element according to any one of claims 1 to 5, wherein the other is a hydrogen atom, an aryl group having up to 14 carbon atoms, a heteroaryl group having up to 14 carbon atoms, a branched alkyl group having up to 10 carbon atoms, an alkenyl group having up to 10 carbon atoms, and a cycloalkyl group having up to 10 carbon atoms.

7. In the above general formula 1, X － However, (FSO ２ ) ２ N － (CF ３ SO ２ ) ２ N － (CN) ４ B － BF ４ － , PF ６ － , and ClO ４ － An electrochromic element according to any one of claims 1 to 6, which is one or more selected from the above.

8. In the above general formula 1, X － However, (FSO ２ ) ２ N － , and (CF ３ SO ２ ) ２ N － An electrochromic element according to any one of claims 1 to 7, which is one or more selected from the above.

9. In the above general formula 1, X － However, (CF ３ SO ２ ) ２ N － The electrochromic element according to any one of claims 1 to 8.

10. In the above general formula 1, W ２＋ However, the electrochromic element according to any one of claims 1 to 9, represented by the following structural formula 1. [Structural formula 1] 【Transformation 5】

11. The electrochromic element according to any one of claims 1 to 10, wherein k is 0 in the general formula 1.

12. In the above general formula 1, R ３ This is expressed by the following general formula 3, R ４ An electrochromic element according to any one of claims 1 to 11, wherein the following general formula 4 is used. [General formula 3] 【Transformation 6】 [General formula 4] 【Transformation 7】 However, in the general formula 3, m represents an integer from 1 to 10, and in the general formula 4, n represents an integer from 1 to 10, and m and n may be the same value or different values.

13. The second electrode further has a second electrochromic layer, The electrochromic element according to any one of claims 1 to 12, wherein the electrolyte layer is located between the first electrochromic layer and the second electrochromic layer.

14. The electrochromic element according to claim 13, wherein the second electrochromic layer contains a polymer obtained by polymerizing a polymerizable material containing a radical polymerizable compound having a triarylamine skeleton.

15. The electrochromic element according to claim 14, wherein the polymerizable material further contains a radical polymerizable compound having a tetraarylbenzidine skeleton.

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