WO2022113702A1

WO2022113702A1 - Electrochromic compound, electrochromic composition, and electrochromic element

Info

Publication number: WO2022113702A1
Application number: PCT/JP2021/040812
Authority: WO
Inventors: Daisuke Goto; Yusuke Kanebako; Kengo TAKASHIMA
Original assignee: Ricoh Company, Ltd.
Priority date: 2020-11-30
Filing date: 2021-11-05
Publication date: 2022-06-02

Abstract

Provided is an electrochromic element including a first electrode, a second electrode facing the first electrode with a space between the first electrode and the second electrode, an electrolyte layer disposed between the first electrode and the second electrode, and a layer including an electrochromic compound represented by General Formula (1) and being disposed on or above the first electrode

Description

ELECTROCHROMIC COMPOUND, ELECTROCHROMIC COMPOSITION, AND ELECTROCHROMIC ELEMENT

The present disclosure relates to an electrochromic compound, an electrochromic composition, and an electrochromic element.

Electrochromic elements, which use coloring and/or decoloring (may be referred to as “coloring and decoloring”) of an electrochromic material (electrochromic compound) causing electrochromism, have been researched and developed as a promising candidate for a display device, such as electronic paper, and a light-shielding unit.

The electrochromic element includes an electrolyte layer and an electrochromic layer between a pair of electrode. When forward voltage or reverse voltage is applied to the electrochromic element, the electrochromic compound is colored and decolored.

In principle, the electrochromic element reversible changes between a colorless state and a colored state. Since the electrochromic element can color in various colors when multiple coloring layers, such as cyan (C), magenta (M), and yellow (Y), are disposed, the electrochromic element is expected as an element that can realize a multicolor display. In order to use the electrochromic element as a transparent display device or a device capable of multicolor display, therefore, the electrochromic compound is desirably a material in a colorless transparent state when it is decolored.

As electrochromic compounds for three primary colors of CMY, red and magenta color materials are proposed (see, for example, PTL 1 and PTL 2). The proposed electrochromic compounds and electrochromic elements using such electrochromic compounds are said to have stability, such as repetitive operations, but color rendering thereof is not sufficiently satisfactory.

Moreover, proposed is an electrochromic element including a compound represented by General Formula (1) achieving excellent reproducibility of magenta, cyan or green, or a cured product of a compound represented by General Formula (1) or a compound (see, for example, PTL 3 and PTL 4).

(In General Formula (1), R₁ to R₅ are each independently a hydrogen atom, a halogen atom, or a monovalent organic group, A is a group represented by any of General Formulae (1-1) to (1-4))

(In General Formulae (1-1) to (1-4), R₁₄, R₁₆, R₁₈, or R₂₀ is a single bond bonded to a nitrogen atom; R₁₅, R₁₇, R₁₉, or R₂₁ is a single bond bonded to a nitrogen atom; R₃₀, R₃₂, R₃₄, or R₃₆ is a single bond bonded to a nitrogen atom; R₃₁, R₃₃, R₃₅, or R₃₇ is a single bond bonded to a nitrogen atom; R₄₂, R₄₃, R₄₄, or R₄₅ is a single bond bonded to a nitrogen atom; R₆ to R₅₂, excluding a single bond bonded to a nitrogen atom, are each independently a hydrogen atom, a halogen atom, or a monovalent organic group; X₁ and X₂ are each independently an oxygen atom, a sulfur atom, or a group represented by General Formula (1-5)

(In General Formula (1-5), R₅₃ and R₅₄ are each independently an alkyl group or an aryl group, where R₅₃ and R₅₄ may be bonded together to form a cyclic structure); X₃ and X₄ are each independently an oxygen atom or a sulfur atom; and X₅ is an oxygen atom or a sulfur atom.)

Japanese Patent No. 6613663 Japanese Unexamined Patent Application Publication No. 2017-008025 Japanese Unexamined Patent Application Publication No. 2020-140053 Japanese Unexamined Patent Application Publication No. 2020-138925

The present disclosure has an object to provide an electrochromic element having excellent durability against repetitive use and favorable coloring.

According to one aspect of the present disclosure, an electrochromic element includes a first electrode, a second electrode facing the first electrode with a space between the first electrode and the second electrode, an electrolyte layer disposed between the first electrode and the second electrode, and a layer including an electrochromic compound represented by General Formula (1). The layer is disposed on or above the first electrode.

In General Formula (1), R₁ to R₂₂ are each a hydrogen atom, a halogen atom, an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an aryl group, a heteroaryl group, an amino group, a group represented by General Formula (2), or a polymerizable functional group including an acryloyl group, a methacryloyl group, an acryloyloxy group, or a methacryloyloxy group; at least one selected from R₁, R₂, and R₁₅ is the group represented by General Formula (2), where R₁₆ to R₂₂ may be identical to or different from each other when a plurality of groups represented by General Formula (2) are present; and at least one selected from R₉ to R₁₄ forms a cyclic structure by bonding to a substituent on an adjacent benzene ring, or inserting a carbon atom, a silicon atom, an oxygen atom, a sulfur atom, or a selenium atom.

The present disclosure can provide an electrochromic element having excellent durability against repetitive use and favorable coloring.

FIG. 1 is a view illustrating an example of a structure of the electrochromic element according to the first embodiment. FIG. 2 is a view illustrating an example of a structure of the electrochromic element according to the second embodiment. FIG. 3 is a view depicting an ultraviolet and visible absorption spectrum of the neutral state of the electrochromic compound of Example 6. FIG. 4 is a view depicting a fluorescence spectrum of the neutral state of the electrochromic compound of Example 6. FIG. 5 is a view depicting the result of cyclic voltammetry of the electrochromic compound of Example 6. FIG. 6 is a view depicting an ultraviolet and visible absorption spectrum of Example 2-1 when colored. FIG. 7 is a view depicting ultraviolet and visible absorption spectra of the electrochromic elements of Examples 2-1, 2-2, and 2-3.

(Electrochromic element)
The electrochromic element of the present disclosure includes a first electrode, a second electrode facing the first electrode with a space between the first electrode and the second electrode, and an electrolyte layer disposed between the first electrode and the second electrode. The electrochromic element includes a layer including an electrochromic compound represented by General Formula (1) disposed on the first electrode.

In General Formula (1), R₁ to R₂₂ are each a hydrogen atom, a halogen atom, an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an aryl group, a heteroaryl group, an amino group, a group represented by General Formula (2), or a polymerizable functional group including an acryloyl group, a methacryloyl group, an acryloyloxy group, or a methacryloyloxy group.
At least one selected from R₁, R₂, and R₁₅ is a group represented by General Formula (2). When a plurality of groups represented by General Formula (2) are present, R₁₆ to R₂₂ may be identical to or different from each other.
At least one selected from R₉ to R₁₄ may form a cyclic structure by bonding to a substituent on a benzene ring, or inserting a carbon atom, a silicon atom, an oxygen atom, a sulfur atom, or a selenium atom.

The present inventors have diligently repeated researches on materials that color in excellent red and magenta through the electrochromic phenomenon focusing on a particular structure of a diarylaminostilbene skeleton that may include a polymerizable functional group. As a result, the present inventors have found an electrochromic compound represented by General Formula (1), by which the present invention has been accomplished.
Specifically, the present inventors have found that the diarylaminostilbene skeleton has a conjugated system where vinyl benzene is bonded to triphenylamine, which generally colors in red to magenta. Moreover, the same tendency can be found with the structure where a phenyl group is introduced in the alpha-site of the stilbene through substitution. Furthermore, it has been also found that coloring in the red to magenta region can be desirably controlled by directly bonding between phenyl groups of the triphenylamine skeleton present in the center, or inserting certain atoms.

In the present disclosure, for example, the color “red” means 32 degrees±30 degrees, preferably 32 degrees±20 degrees, and more preferably 32 degrees±10 degrees, and the color “magenta” means around 355 degrees±30 degrees, preferably around 355 degrees±20 degrees, and more preferably 355 degrees±10 degrees based on the Japan color with hue h of the CIE Lab color system or the CIE LCh color system as the standard.

PTL 3 and PTL 4 (Japanese Unexamined Patent Application Publication Nos. 2020-140053 and 2020-138925), which are related art, disclose clearly different structures, as a cyclic structure including selenium (Se) is included in General Formula (1-1), and at least one of R₁, R₂, and R₁₅ in the present disclosure does not include a group represented by General Formula (2). Moreover, in the related art, reproducibility of magenta of the Japan color is not sufficient, and desirable coloring of red and magenta cannot be obtained.

(Electrochromic compound)
The electrochromic compound of the present disclosure is represented by General Formula (1), and has a diarylaminostilbene skeleton where a styryl group is substituted.
The electrochromic compound preferably has a diphenylaminostilbene skeleton where two phenyl groups are introduced into a nitrogen atom constituting a diarylaminostilbene skeleton by substitution, and is more preferably a radical polymerizable compound.

Examples of the halogen atom in General Formula (1) include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

In General Formula (1), the alkyl group is, for example, preferably a straight-chain, branched-chain, or cyclic C1-C30 alkyl group considering readily availability of raw materials. Among the cyclic C1-C30 alkyl group, a cyclic C1-C18 alkyl group is more preferable.
Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, a tert-butyl group, an isopropyl group, an isobutyl group, a pentyl group, a hexyl group, a heptyl group, an ethylhexyl group, an octyl group, a decyl group, a dodecyl group, a 2-butyloctyl group, an octadecyl group, a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and an adamantyl group.

In General Formula (1), the alkenyl group is, for example, preferably a straight-chain, branched-chain, or cyclic C1-C30 alkenyl group, considering readily availability of raw materials. Among the cyclic C1-C30 alkenyl group, a cyclic C1-C18 alkenyl group is more preferable.
Examples of the alkenyl group include a vinyl group, a methylvinyl group, a cis- or trans-styryl group, an alpha-phenylstyryl group (e.g., dibenzoethenyl group) and groups obtained by taking 2 hydrogen atoms away from a methyl group, a ethyl group, a propyl group, a butyl group, a tert-butyl group, an isopropyl group, an isobutyl group, a pentyl group, a hexyl group, a heptyl group, an ethylhexyl group, an octyl group, a decyl group, a dodecyl group, a 2-butyloctyl group, an octadecyl group, a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, an adamantyl group, etc. to form double bonds. Examples thereof include substituents represented by the following structural formulae.

Considering thermal and chemical stability of the double bond site, alkenyl groups represented by the following structural formulae are preferable.

In General Formula (1), the alkynyl group is, for example, preferably a straight-chain, branched-chain, or cyclic C1-C30 alkynyl group, considering readily availability of raw materials. Among the cyclic C1-C30 alkynyl group, a cyclic C1-C18 alkynyl group is more preferable.
Examples of the alkenyl group include a vinyl group, a methyl vinyl group, a styryl group, and an alpha-phenylstyryl group (e.g., dibenzoethenyl group), and also groups each including a triple bond formed by taking 4 hydrogen atoms away from groups, such as a methyl group, an ethyl group, a propyl group, a butyl group, a tert-butyl group, an isopropyl group, an isobutyl group, a pentyl group, a hexyl group, a heptyl group, an ethylhexyl group, an octyl group, a decyl group, a dodecyl group, a 2-butyloctyl group, an octadecyl group, a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and an adamantyl group. Examples thereof include an ethenyl group, and a phenylethenyl group.

In General Formula (1), the alkoxy group is a group -O(alkyl) having the specific number of carbon atoms. Examples of the alkoxy group include a C1-C6 alkoxy group.
Examples of the C1-C6 alkoxy group include a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, a 1-methylpropoxy group, a 2-methylpropoxy group, a tert-butoxy group, a pentyloxy group, a 1-methylbutoxy group, a 2-methylbutoxy group, a 3-methylbutoxy group, a 1,1-dimethylpropoxy group, a 2,2-dimethylpropoxy group, a 1,2-dimethylpropoxy group, a 1-ethylpropoxy group, a hexyloxy group, a 1-methylpentyloxy group, a 2-methylpentyloxy group, a 3-methylpentyloxy group, a 4-methylpentyloxy group, a 1,1-dimethylbutoxy group, a 2,2-dimethylbutoxy group, a 3,3-dimethylbutoxy group, a 1,2-dimethylbutoxy group, a 1,3-dimethylbutoxy group, a 2,3-dimethylbutoxy group, a 1-ethylbutoxy group, a 2-ethylbutoxy group, and a 1-ethyl-2-methylpropoxy group.

Examples of the aryl group in General Formula (1) include a phenyl group, an o-tolyl group, a m-tolyl group, a p-tolyl group, a p-chlorophenyl group, a p-fluorophenyl group, a p-trifluorophenyl group, a naphthyl group, a biphenyl group, an anthryl group, a phenanthryl group, a pyrenyl group, a fluorenyl group, a benzopyrenyl group, a chrysenyl group, and a triphenylene group.

In General Formula (1), the heteroaryl group is, for example, preferably a C2-C12 heteroaryl group.
Examples of constitutional elements of the C2 or higher heteroaryl group include a nitrogen atom, a sulfur atom, an oxygen atom, a silicon atom, or a selenium atom. Among the above-listed examples, the C2 or higher heteroaryl group preferably includes at least one selected from the group consisting of a nitrogen atom, a sulfur atom, and an oxygen atom.
Examples of the C2 or higher heteroaryl group include monocyclic heteroaryl groups and polycyclic heteroaryl groups.

Examples of the monocyclic heteroaryl groups include a pyridine ring, a pyrimidine ring, a pyridazine ring, a pyrazine ring, tetrazine, a thiophene ring, a furan ring, pyrrole, imidazole, pyrazole, a thiazole ring, an oxazole ring, isoxazole, an oxadiazole ring, a triazine ring, a tetrazole ring, and a triazole ring.

Examples of the polycyclic heteroaryl groups include a quinolone group, an isoquinoline group, a quinazoline group, a phthalazine group, an indole group, a benzothiophene group, a benzofuran group, a benzoimidazole group, a benzothiodiazole group, an acridine group, an acridane group (9,10-dihydroacridine), a phenoxazine group, a phenothiazine group, a carbazole group, a 9-phenylcarbazole group, a 9-ethylcarbazole group, a benzodithiophene group, a benzodifuran group, a dibenzofuran group, and a dibenzothiophene group.

The polycyclic heteroaryl group may be a group where an aryl group and a heteroaryl group are bonded with a covalent bond, or a group where an aryl group and a heteroaryl group are condensed to form a ring together. Examples of the group where an aryl group and a heteroaryl group are bonded with a covalent bond, or the group where an aryl group and a heteroaryl group are condensed to form a ring together include a biphenyl group, a terphenyl group, a 1-phenylnaphthalene group, and a 2-phenylnaphthalene group.
In General Formula (1), the aryloxy group and the heteroaryloxy group are a group -O(aryl) having the specific number of carbon atoms, and a group -O(heteroaryl) having the specific number of carbon atoms, respectively.

Examples of the amino group include, as well as non-substituted amino groups, substituted amino groups where an alkyl group, an aryl group, or a heteroaryl group is introduced into a nitrogen atom through substitution. Examples thereof include a diethylamino group, an ethylphenylamino group, a 4-diethylaminophenyl group, a triphenylamine group, a diphenylamino group, and a cyclic amino group (e.g., a piperazine group, a piperidine group, and a morpholyl group.

The monocyclic heteroaryl, polycyclic heteroaryl, and amino group are preferably not electron-rich nitrogen-containing rings, because the compound with any of the monocyclic heteroaryl, polycyclic heteroaryl, and amino group as an oxidation-coloring electrochromic material increases sites that tend to be oxidized other than in the main skeleton, leading unexpected change in color tone. Moreover, the monocyclic heteroaryl, polycyclic heteroaryl, and amino group are also preferably not electron-deficient nitrogen-containing rings that have acceptor characteristics strong enough not to oxidize the main skeleton. Examples of the former group include carbazole, phenoxazine, phenothiazine, acridane, a diethylamino group, an ethylphenylamino group, a 4-diethylaminophenyl group, a triphenylamine group, a diphenylamino group, and a cyclic amino group (e.g., a piperazine group, a piperidine group, and a morpholyl group). Examples of the latter group include pyridine, pyrimidine, thiazole, oxazole, benzimidazole, quinoline, and acridine.

The alkyl group, alkenyl group, alkynyl group, aryl group, alkoxy group, aryloxy group, alkylthio group, arylthio group, heteroaryl group or amino group in General Formula (1) may be substituted with a substituent.
Examples of the substituent include a halogen atom, a nitro group, a cyano group, a carboxyl group, an alkyl group, an alkoxy group, an aryloxy group, an aryl group, and an aralkyl group.

In General Formula (1), the polymerizable functional group may be any group as long as the polymerizable functional group has a carbon double bond (C=C) and is a polymerizable group. Examples of the polymerizable functional group include a 1-substituted ethylene functional group and a 1,1-substituted ethylene functional group below.

(1) Examples of the 1-substituted ethylene functional group include a functional group presented by General Formula (i) below.

In General Formula (i), X₁ is an arylene group, an alkenylene group, －CO－, －COO－, －CON(R₁₀₀)－ (R₁₀₀ is a hydrogen atom, an alkyl group, an aralkyl group, or an aryl group), or －S－, where the arylene group or alkenylene group may have a substituent.

Examples of the arylene group include a phenylene group, and a naphthylene group. The phenylene group may have a substituent.

Examples of the alkenylene group include an ethenylene 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.

Examples of the polymerizable functional group represented by General Formula (i) include a vinyl group, a styryl group, a 2-methyl-1,3-butadienyl group, a vinylcarbonyl group, an acryloyloxy group, an acryloylamide group, and a vinyl thioether group.

(2) Examples of the 1,1-substituted ethylene functional group include a functional group represented by General Formula (ii) below.

In General Formula (ii), Y is an alkyl group, an aralkyl group, an aryl group, a halogen atom, a cyano group, a nitro group, an alkoxy group, or －COOR₁₀₁ (R₁₀₁ is a hydrogen atom, an alkyl group, an aralkyl group, an aryl group, or CONR₁₀₂R₁₀₃ [R₁₀₂ and R₁₀₃ are each a hydrogen atom, an alkyl group, an aralkyl group, or an aryl group, where R₁₀₂ and R₁₀₃ may be identical or different]). The above-listed groups may have a substituent.
Moreover, X₂ is a substituent that is same as any of the groups listed as X₁ of General Formula (i), or an alkylene group, where at least one of Y and X₂ is an oxycarbonyl group, a cyano group, an alkenylene group, or an aromatic ring.

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.
Examples of the alkoxy group include a methoxy group, an ethoxy group, and a group with which an ethylene glycol unit or propylene glycol unit is condensed, such as diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol, tetraethylene glycol, tetrapropylene glycol, polyethylene glycol, and polypropylene glycol.

Examples of the polymerizable functional group represented by General Formula (ii) include an alpha- chloro acryloyloxy group, a methacryloyloxy group, an alpha-cyanoethylene group, an alpha-cyanoacryloyloxy group, an alpha-cyanophenylene group, and a methacryloylamino group.

Examples of a substituent further substituting the substituents of 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; and an aralkyl group, such as a benzyl group and a phenethyl group.

Among the functional groups represented by General Formula (i) or General Formula (ii), a group including at least one selected from the group consisting of an acryloyl group, a methacryloyl group, an acryloyloxy group, and a methacryloyloxy group is preferable, a group including an acryloyloxy group or a methacryloyloxy group is more preferably considering synthesis, and a group including an acryloyloxy group is particularly preferable considering polymerization speed and a polymerization completion rate.

Considering high durability against oxidation and reduction, the polymerizable functional group in General Formula (1) is, for example, preferably introduced through substitution at a terminal of a C1 or higher alkyl group or alkoxy group, a C6 or higher aryl group or phenoxy group, or an aryl group substituted with an alkyl group or an alkoxy group, more preferably introduced at a terminal of an alkyl group or alkoxy group, and particularly preferably introduced at an alkoxy group in which a hydrogen atom is not present in the benzyl site.
The number of carbon atoms of the alkyl group or alkoxy group is preferably 3 or greater.

At least one of R₁ to R₂₂ is preferably a polymerizable functional group including an acryloyl group, a methacryloyl group, an acryloyloxy group, or a methacryloyloxy group.

The polymerizable functional group is preferably bonded to a main skeleton of the electrochromic compound of the present disclosure via a C2 or higher alkyl group.

R₁, R₂, and R₁₅ are preferably all a halogen atom, an alkyl group, an alkoxy group, a group represented by General Formula (2), an acryloyl group, or a polymerizable functional group including a methacryloyl group, an acryloyloxy group, or a methacryloyloxy group.
This is because, when hydrogen atoms are present in para-sites of benzene rings introduced to a nitrogen atom of triphenylamine or benzidine, multimerization of the triphenylamine or benzidine occurs during oxidation and/or reduction to thereby change optical properties of the triphenylamine or benzidine, and therefore the better electrical and optical stability can be obtained by substituting the para-sites with an alkyl group or alkoxy group.

The number of groups represented by General Formula (2) in R₁, R₂, and R₁₅ is preferably 2 or less. It is preferred that R₁, R₂, and R₁₅ are not hydrogen atoms. The conjugated system is expanded as the group represented by General Formula (2) is introduced in the para-site through substitution, to thereby shift the absorption wavelength of the compound to the longer wavelength side to extend into the visible range. As a result, tinting may occur in the neutral state, when the compound is used as an electrochromic compound. Therefore, the number of group represented by General Formula (2) is 2 or less, more preferably 1 or less.

In General Formula (1), among R₉ to R₁₄ that are ortho-sites based on the nitrogen atom of each benzene ring bonded to the nitrogen atom of triphenylamine, two sites are preferably bonded to form a ring structure. Specifically, the ring structure is a structure represented by General Formula (3), and X₁ and X₂ are each independently an embodiment of direct bond (e.g., formation of carbazole skeleton), a substituted or unsubstituted carbon atom, a substituted or unsubstituted silicon atom, an oxygen atom, a sulfur atom, or a selenium atom.
In case of the carbon atom and the silicon atom, the carbon atom and the silicon atom may be substituted with an alkyl group, an alkoxy group, or an aryl group, where the alkyl group, the alkoxy group, and the aryl group may be bonded to each other to form a ring structure.
X₁ and X₂ are preferably each an embodiment of direct bond, a substituted carbon atom, or a substituted silicon atom. In case of the oxygen atom and the sulfur atom, a resultant compound has high donor characteristics, and therefore the edge of the absorption wavelength range of the compound in the neutral state extends to the visible region, which tends to appear as tinting. Particularly when a crosslink is formed with a plurality of oxygen atoms or sulfur atoms, watchful eyes may be particularly kept on tinting due to development of the conjugated system. Moreover, use of a selenium atom may not be preferable considering toxicity and difficulty of synthesis compared to an oxygen atom and a sulfur atom, and use thereof may be avoided.

Examples of the compound represented by General Formula (1) include the following exemplary compounds. However, the electrochromic compound of the present invention is not limited to the following exemplary compounds. In the following exemplary compounds, “MeO－” denotes a methoxy group, and “tBu－” denotes a tertiary butyl group.

<Electrochromic composition>
The electrochromic composition for use in the present disclosure includes the electrochromic compound of the present disclosure, and may further include other components according to the necessity.

As described above, the electrochromic compound of the present disclosure is a radical polymerizable compound having a diarylaminostilbene skeleton. Therefore, the electrochromic compound is important for imparting an electrochromic function involving redox reactions at a surface of a first electrode of the below-described electrochromic element of the present disclosure.

In addition to the electrochromic compound of the present disclosure, the electrochromic composition preferably further include another radical polymerizable compound.

<Another radical polymerizable compound>
Another radical polymerizable compound is different from the electrochromic compound of the present disclosure and a compound including at least radical polymerizable functional group. As another radical polymerizable compound, a plurality of compounds each having a triphenylamine skeleton or benzidine skeleton may be used.

Examples of another radical polymerizable compound include radical polymerizable compounds, such as a monofunctional radical polymerizable compound, a bifunctional radical polymerizable compound, and a trifunctional radical polymerizable compound, a trifunctional or higher radical polymerizable compound, functional monomers, and radical polymerizable oligomers. Among the above-listed examples, a bifunctional or higher radical polymerizable compound is particularly preferable. Examples of the radical polymerizable functional group in any of the above-listed other radical polymerizable compounds are identical to any of the examples listed as the radical polymerizable functional group of the electrochromic compound of the present disclosure. Among the above-listed examples, an acryloyloxy group and a methacryloyloxy group are particularly preferable

Examples of the monofunctional radical polymerizable compound include 2-(2-ethoxyethoxy)ethylacrylate, methoxy polyethylene glycol monoacrylate, methoxy polyethylene glycol monomethacrylate, phenoxy polyethylene glycol acrylate, 2-acryloyloxyethylsuccinate, 2-ethylhexylacrylate, 2-hydroxyethylacrylate, 2-hydroxypropylacrylate, tetrahydrofurfuryl acrylate, 2-ethylhexylcarbitol acrylate, 3-methoxybutylacrylate, benzylacrylate, cyclohexyl acrylate, isoamyl acrylate, isobutyl acrylate, methoxy triethylene glycol acrylate, phenoxy tetraethylene glycol acrylate, cetyl acrylate, isostearyl acrylate, stearyl acrylate, and a styrene monomer. The above-listed examples may be used alone or in combination.

Examples of the bifunctional radical polymerizable compound 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. The above-listed examples may be used alone or in combination.

Examples of the trifunctional or higher radical polymerizable compound 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, tris(acryloyloxyethyl) 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 phosphoric acid triacrylate, and 2,2,5,5-tetrahydroxymethylcyclopentanone tetraacrylate. The above-listed examples may be used alone or in combination. In the present specification, the term “EO-modified” means ethyleneoxy-modified, and the term “PO-modified” means propyleneoxy-modified.

Examples of the functional monomer include: a monomer substituted with a fluorine atom, such as octafluoropentyl acrylate, 2-perfluorooctylethylacrylate, 2-perfluorooctylethylmethacrylate, and 2-perfluoroisononylethylacrylate; vinyl monomers including a polysiloxane group having from 20 through 70 repeating units of siloxane, such as acryloyl polydimethylsiloxane ethyl, methacryloyl polydimethylsiloxane ethyl, acryloyl polydimethylsiloxane propyl, acryloyl polydimethylsiloxane butyl, and diacryloyl polydimethylsiloxane diethyl, disclosed in Japanese Examined Application Publication Nos. 05-60503 and 06-45770; acrylate; and methacrylate. The above-listed examples may be used alone or in combination.

Examples of the radical polymerizable oligomer include an epoxy acrylate-based oligomer, a urethane acrylate-based oligomer, and a polyester acrylate-based oligomer.

The electrochromic compound of the present disclosure and another radical polymerizable compound may be copolymerized through a polymerization reaction. The electrochromic compound or the radical polymerizable compound, or both preferably have 2 or more radical polymerizable functional groups in view of formation of a polymerized product or crosslinked product. The polymerized product or crosslinked product is preferable because, in addition to mechanical strength thereof, the polymerized product or crosslinked product is not dissolved with various organic solvents or electrolytes, and does not cause interlayer migration when a multi-layer structure is formed.

An amount of the electrochromic compound is preferably 10% by mass or greater but 100% by mass or less, and more preferably 30% by mass or greater but 90% by mass or less, relative to a total amount of the electrochromic composition. When the amount thereof is 10% by mass or greater, an electrochromic function of the first electrochromic layer of the below-described electrochromic element is sufficiently exhibited, excellent durability against repetitive use upon application of voltage is achieved, and excellent coloring sensitivity is obtained. When the amount thereof is 100% by mass or less, an electrochromic function of the first electrochromic layer is exhibited, and sufficiently high coloring sensitivity relative to a thickness thereof can be obtained. When the amount thereof is 100% by mass, compatibility between the electrochromic compound and an ionic liquid used for charge transfer may be low, and therefore deteriorations in electric properties, such as reduction in durability as a result of repetitive use upon application of voltage may be caused. Notably, electric properties required vary depending on a process in which the electrochromic compound is used. In view of a balance between coloring sensitivity and durability against repetitive use, the amount of the electrochromic compound is preferably 30% by mass or greater but 90% by mass or less.

The electrochromic composition preferably includes filler and a polymerization initiator.

-Filler-
The filler is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include inorganic filler and organic filler.

Examples of the inorganic filler include: metal powder, such as copper, tin, aluminium, and indium; metal oxide, such as silicon oxide (silica), tin oxide, zinc oxide, titanium oxide, aluminium oxide (alumina), zirconium oxide, indium oxide, antimony oxide, bismuth oxide, calcium oxide, antimony-doped tin oxide (ATO), and tin-doped indium oxide; and metal fluoride, such as tin fluoride, calcium fluoride, and aluminium fluoride. The above-listed examples may be used alone or in combination. Among the above-listed examples, the metal oxide is preferable, and silica, alumina, and antimony-doped tin oxide (ATO) are particularly preferable, considering transparency, stability, and easiness of a surface treatment.

Examples of the organic filler include: resins, such as polyester, polyether, polysulfide, polyolefin, silicone, and polytetrafluoroethylene; low molecular compound, such as fatty acid; and pigments, such as phthalocyanine. The above-listed examples may be used alone or in combination. The average primary particle diameter of the filler is preferably 1 micrometer or less, and more preferably 10 nm or greater but 1 micrometer or less. When the average primary particle diameter of the filler is 1 micrometer or less, coarse particles are not formed, a resultant film has an excellent surface configuration, and excellent surface smoothness.

An amount of the filler based on the solid content is preferably 0.3 parts by mass or greater but 1.5 parts by mass or less, and more preferably 0.6 parts by mass or greater but 0.9 parts by mass or less, relative to 100 parts by mass of a total amount of the radical polymerizable compounds. When the amount of the filler is 0.3 parts by mass or greater, an effect obtainable by adding the filler can be sufficiently exhibited, and excellent film formability can be obtained. When the amount of the filler is 1.5 parts by mass or less, an appropriate ratio of the triarylamine compound is maintained, and excellent electrochemical properties of the resulting electrochromic element are obtained.

-Polymerization initiator-
The electrochromic composition preferably optionally includes a polymerization initiator in order to facilitate an efficient cross-liking reaction between the electrochromic compound of the present disclosure and other radical polymerizable compounds. Examples of the polymerization initiator include a thermal polymerization initiator and a photopolymerization initiator. In view of polymerization efficiency, the polymerization initiator is preferably a photopolymerization initiator.

The thermal polymerization initiator is not particularly limited and may be appropriately selected depending on the intended purpose. Examples of the thermal polymerization initiator include: a peroxide-based initiator, such as 2,5-dimethylhexane-2,5-dihydroperoxide, dicumyl peroxide, benzoyl peroxide, t-butylcumyl peroxide, 2,5-dimethyl-2,5-di(peroxybenzoyl)hexyne-3, di-t-butylperoxide, t-butylhydroperoxide, cumene hydroperoxide, and lauroyl peroxide; and an azo-based initiator, such as azobisisobutyl nitrile, azobiscyclohexane carbonitrile, methyl azobisisobutyrate, azobisisobutylamidine hydrochloride, and 4,4′-azobis-4-cyanovaleric acid. The above-listed examples may be used alone or in combination.

The photopolymerization initiator is not particularly limited and may be appropriately selected depending on the intended purpose. Examples of the photopolymerization initiator include: an acetophenone-based or ketal-based photopolymerization initiator, such as diethoxyacetophenone, 2,2-dimethoxy-1,2-diphenylethan-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, 4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone-1, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2-methyl-2-morpholino(4-methylthiophenyl)propan-1-one, and 1-phenyl-1,2-propanedione-2-(o-ethoxycarbonyl)oxime; benzoin ether-based photopolymerization initiators, such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isobutyl ether, and benzoin isopropyl ether; a benzophenone-based photopolymerization initiator, such as benzophenone, 4-hydroxybenzophenone, methyl o-benzoyl benzoate, 2-benzoylnaphthalene, 4-benzoylbiphenyl, 4-benzoyl phenyl ether, acrylated benzophenone, and 1,4-benzoylbenzene; and a thioxanthone-based photopolymerization initiator, such as 2-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, and 2,4-dichlorothioxanthone. The above-listed examples may be used alone or in combination.

Examples of other photopolymerization initiators include ethyl anthraquinone, 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, methylphenylglyoxylic acid ester, 9,10-phenanthrene, acridine-based compounds, triazine-based compounds, and imidazole-based compounds. The above-listed examples may be used alone or in combination.

Note that, a compound having an effect of accelerating photopolymerization may be used alone or in combination with the photopolymerization initiator. Examples of such a compound include triethanolamine, methyl diethanol amine, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, (2-dimethylamino)ethyl benzoate, and 4,4′-dimethylaminobenzophenone.

An amount of the polymerization initiator is preferably 0.5 parts by mass or greater but 40 parts by mass or less, and more preferably 1 part by mass or greater but 20 parts by mass or less, relative to 100 parts by mass of a total amount of the radical polymerizable compounds.

<Other components>
The electrochromic composition may further include other components according to the necessity. The above-mentioned other components are not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a solvent, a plasticizer, a leveling agent, a sensitizer, a dispersant, a surfactant, and an antioxidant.

The electrochromic composition may include a crosslinking agent, and may be a copolymerized product (e.g., linear copolymer having a linear structure) obtained by polymerizing the electrochromic compound of the present disclosure. Moreover, the electrochromic composition may be a crosslinked product having a branched structure or a three-dimensional network structure obtained by crosslinking the electrochromic compound of the present disclosure. The crosslinking agent is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include isocyanurates, an amino resin, a phenol resin, amines, an epoxy compound, monofunctional (meth)acrylate, polyfunctional (meth)acrylate having 2 or more ethylenically unsaturated bonds per molecule, acrylic acid ester, and methacrylic acid ester. Among the above-listed examples, isocyanurates are preferable, and polyisocyanate having two or more isocyanate groups is particularly preferable.

Since the electrochromic composition includes the electrochromic compound of the present disclosure, desirable properties of the electrochromic element can be achieved. As described above, examples of the desired properties of the electrochromic element include that the electrochromic composition is transparent in a neutralized state, that the electrochromic composition is soluble, and that an electrochromic layer can be laminated.

(Electrochromic element)
The electrochromic element of the present disclosure includes a first electrode, a second electrode, and an electrolyte layer disposed between the first electrode and the second electrode. The electrochromic element may further include other members according to the necessity.
The electrochromic element includes an electrochromic layer including the electrochromic composition for use in the present disclosure disposed on or above the first electrode, or an electrolyte layer including the electrochromic composition for use in the present disclosure.

The electrochromic composition has excellent light fastness and durability against repetitive use, and can achieve physical properties suitable for an electrochromic element. Therefore, the electrochromic element can use the electrochromic element with the optimal structural conditions in the optimal structural position. Accordingly, the electrochromic element of the present disclosure exhibits excellent effects, particularly excellent durability against repetitive use and light fastness compared to conventional electrochromic elements.

In the present disclosure, an embodiment where the electrochromic element of the present disclosure includes an electrochromic layer including the electrochromic composition for use in the present disclosure is referred to as an electrochromic element of the first embodiment. An embodiment where the electrochromic element of the present disclosure includes an electrolyte layer including the electrochromic composition for use in the present disclosure is referred to as an electrochromic element of the second embodiment. Hereinafter, the electrochromic elements of the first and second embodiments will be described hereinafter.

-Electrochromic element of first embodiment-
The electrochromic element of the first embodiment will be described. In order to facilitate clear understanding, a scale of each member in drawings may be different from the actual scale between members. For the matter of convenience in describing the layer structure etc., moreover, the embodiment below is described with a drawing in which the first support is arranged at the bottom. However, the production or use of the first embodiment is not necessarily performed with such an arrangement. In the descriptions below, one side of the first support with respect to the thickness direction is referred to above, up, or top, and the other side of the support may be referred to as below, under, or bottom.

FIG. 1 is a view illustrating one example of the structure of the electrochromic element of the present embodiment. As illustrated in FIG. 1, the electrochromic element 10A of the present disclosure includes a first support 11, a display electrode (first electrode) 12, a first electrochromic layer 13, an electrolyte layer 14A, a second electrochromic layer 15, a counter electrode (second electrode) 16, and a second support 17, which are sequentially disposed in this order from the side of the first support 11.

The display electrode 12 is disposed on the top surface of the first support 11, and the first electrochromic layer 13 is disposed on the display electrode 12. Meanwhile, the counter electrode 16 is disposed on the bottom surface of the second support 17, and the second electrochromic layer 15 is disposed on the bottom surface of the counter electrode 16. The display electrode 12 and the counter electrode 16 are arranged to face each other with a predetermined gap between the display electrode 12 and the counter electrode 16, and the electrolyte layer 14A is disposed between the both electrodes (i.e., the display electrode 12 and the counter electrode 16).

In the electrochromic element 10A of the present embodiment, the first electrochromic layer 13 colors and decolors at the surface of the display electrode 12 due to redox reactions, and the second electrochromic layer 15 colors and decolors at the surface of the counter electrode 16 due to redox reactions.

Each member constituting the electrochromic element 10A of the present embodiment will be described hereinafter.

<First electrochromic layer>
The first electrochromic layer includes the electrochromic composition for use in the present disclosure. In the present embodiment, the electrochromic composition is referred to as a first electrochromic composition in order to distinguish from the below-described second electrochromic composition.

In the present embodiment, as described above, the first electrochromic composition preferably includes the electrochromic compound of the present disclosure and another radical polymerizable compound considering solubility of a polymer of the first electrochromic composition and durability.

A single layer of the first electrochromic layer is disposed on the first electrode, but the layer structure of the first electrochromic layer is not limited to such example. Two or more layers of the first electrochromic layer may be disposed on the first electrode.

The first electrochromic layer is disposed on an entire surface of the first electrode. The arrangement of the first electrochromic layer is not limited to such embodiment. The first electrochromic layer may be disposed on part of the first electrode.

The first electrochromic layer may be formed by the below-described method for producing an electrochromic element. The average thickness of the first electrochromic layer is preferably 0.1 micrometers or greater but 30 micrometers or less, and more preferably 0.4 micrometers or greater but 10 micrometers or less.

<First electrode and second electrode>
A material of the first electrode and a material of the second electrode are not particularly limited as long as the materials thereof are each a transparent conductive material. The material of the first electrode and the material of the second electrode may be appropriately selected depending on the intended purpose. Examples of the material of the first electrode and the material of the second electrode include inorganic materials, such as tin-doped indium oxide (may be referred to as “ITO” hereinafter), fluorine-doped tin oxide (may be referred to as “FTO” hereinafter), antimony-doped tin oxide (may be referred to as “ATO” hereinafter), and zinc oxide. Among the above-listed examples, InSnO, GaZnO, SnO, In₂O₃, and ZnO are preferable.

Moreover, it is also possible to use an electrode which is prepared by forming transparent carbon nanotubes, or a highly-conductive non-transparent material, such as Au, Ag, Pt, and Cu, into a fine network, to improve conductivity with maintaining transparency.

A thickness of the first electrode and a thickness of the second electrode are both adjusted to attain an electric resistance value sufficient to cause a redox reaction of the first electrochromic layer and a redox reaction of the second electrochromic layer. When ITO is used as the material of the first electrode and the material of the second electrode, for example, the thickness of the first electrode and the thickness of the second electrode are each preferably 50 nm or greater but 500 nm or less.

As a production method of the first electrode and a production method of the second electrode, for example, vacuum vapor deposition, sputtering, ion plating, etc. may be used. The production methods thereof are not particularly limited as long as the method can apply the materials of the first electrode or the materials of the second electrode through coating. Any of various coating or printing methods may be used. Examples thereof include 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, flexo printing, offset printing, reverse printing, and inkjet printing.

<Electrolyte layer>
The electrolyte layer is formed of an electrolyte filling the gap between the first electrode and the second electrode. The electrolyte is introduced by injecting the electrolyte from injection holes formed in a sealing material disposed between the first electrode and the second electrode to fill the gap between the first electrode and the second electrode.

As the electrolyte, for example, inorganic ionic salts (e.g., alkali metal salts and alkaline earth metal salts), quaternary ammonium salts, and acid or alkaline supporting electrolytes may be used. Specific examples thereof include LiClO₄, LiBF₄, LiAsF₆, LiPF₆, LiCF₃SO₃, LiCF₃COO, KCl, NaClO₃, NaCl, NaBF₄, NaSCN, KBF₄, Mg(ClO₄), and Mg(BF₄)₂.

As a material of the electrolyte, an ionic liquid may be used. Among ionic liquids, an organic ionic liquid is preferable because an organic ionic liquid has a molecular structure that allows the organic ionic liquid to be in a liquid state in a wide temperature range including room temperature. Examples of a cationic component of the molecular structure of the organic ionic liquid include: imidazole derivatives, such as N,N-dimethylimidazole salts, N,N-methylethylimidazole salts, and N,N-methylpropylimidazole salts; pyridinium derivatives, such as N,N-dimethylpyridinium salts, and N,N-methylpropylpyridinium salts; and aliphatic quaternary ammonium salts, such as trimethylpropyl ammonium salts, trimethylhexyl ammonium salts, and triethylhexyl ammonium salts. Considering stability in the atmosphere, moreover, a fluorine-containing compound is preferably used as an anionic component. Examples thereof include BF₄ ^-, CF₃SO₃ ^-, PF₄ ^-, (CF₃SO₂)₂N^-, and tetracyanoboron anion (B(CN)₄ ^-).

As a material of the electrolyte, an ionic liquid including an arbitrary combination of a cationic component and an anionic component is preferably used. The ionic liquid may be directly dissolved in a photopolymerizable monomer, an oligomer, or a liquid crystal material. When the solubility of the electrolyte is poor, the electrolyte may be dissolved in a small amount of a solvent, and the resultant solution may be mixed with the photopolymerizable monomer, oligomer, or liquid crystal material. Examples of the solvent include propylene carbonate, acetnitrile, γ-butyrolactone, ethylene carbonate, sulfolane, dioxolane, tetrahydrofuran, 2-methyltetrahydrofuran, dimethyl sulfoxide, 1,2-dimethoxyethane, 1,2-ethoxymethoxyethane, polyethylene glycol, alcohols, and mixed solvents thereof.

The electrolyte is not necessarily a low-viscous liquid, and may be in any of various states, such as a gel, a cross-linked polymer, and a liquid crystal dispersion. It is advantageous to form the electrolyte into a gel or solid state in view of an improvement in strength of a resultant element, and an improvement in reliability of the element. A solidification method is preferably to retain the electrolyte and the solvent in a polymer because high ion conductivity and a solid strength can be obtained. Moreover, the polymer resin is preferably a photocurable resin because an electrochromic element can be produced at a low temperature within a short period compared to a method where a thin film is formed by thermal polymerization or evaporating a solvent.
The average thickness of the electrolyte layer formed of the electrolyte is not particularly limited and may be appropriately selected depending on the intended purpose. The average thickness thereof is preferably 100 nm or greater but 10 micrometers or less.

<Second electrochromic layer>
The second electrochromic layer composed of a single layer is disposed on the bottom surface of the second electrode, but the arrangement of the second electrochromic layer is not limited to the above-described arrangement. Two or more layers of the second electrochromic layer may be disposed. Moreover, the second electrochromic layer may be disposed on the entire bottom surface of the second electrode, but the arrangement of the second electrochromic layer is not limited to the above-described arrangement. The second electrochromic layer may be disposed on part of the bottom surface of the second electrode.

The second electrochromic layer may include a second electrochromic compound that is a compound (viologen compound) represented by General Formula (I) below. The second electrochromic layer include an electrochromic composite where the viologen compound represented by General Formula (I) is adsorbed on conductor nanostructures or semiconductor nanostructures (i.e., conductor or semiconductor nanostructures). The viologen compound represented by General Formula (I) can be bonded to or adsorbed on the conductor or semiconductor nanostructures. When the electrochromic composite is used in an electrochromic element, the electrochromic element colors mainly in blue, and excellent image memory, i.e., colored image retention, can be obtained.

Other than the viologen compound represented by General Formula (I), the second electrochromic layer may include a phosphonic acid compound represented by General Formula (II) or straight-chain alkyl phosphonate disclosed in Japanese Unexamined Patent Application Publication No. 2017-111434. Alternatively, the phosphonic acid compound or straight-chain alkyl phosphonate may be adsorbed together with the viologen compound in the second electrochromic layer.

-Viologen compound-
The viologen compound represented by General Formula (I) will be described.
In General Formula (I), R₁ and R₂ are each a hydrogen atom, an aryl group having 14 or less carbon atoms, a heteroaryl group, a branched alkyl group having 10 or less carbon atoms, an alkenyl group, a cycloalkyl group, and a functional group that can be bonded to a hydroxyl group; n and m are each 0 or an integer of from 1 through 10; and X^- is an ion neutralize the charge.

In the more preferable embodiment, R₁ or R₂ is a functional group that can be bonded to a hydroxyl group. As a result, adsorption and fixation of the viologen compound onto the transparent electrode (e.g., ITO) is realized. In the case where bearing particles formed of metal oxide are disposed on a transparent electrode, similarly, adsorption and fixation of the second electrochromic layer to the transparent electrode is realized. Therefore, it is advantageous that R₁ or R₂ is a functional group that can be bonded to a hydroxyl group. In a particularly preferable embodiment, R₁ and R₂ are both a functional group that can be bonded to a hydroxyl group.

Examples of the functional group that can be bonded to a hydroxyl group include a phosphonic acid group, a phosphoric acid group, a carboxylic acid group, a sulfonyl group, a silyl group, and a silanol group. Among the above-listed examples, a phosphoric acid group, a phosphoric acid group, and a carboxyl group are preferable, and a phosphoric acid group is more preferable, considering simplicity of synthesis, adsorption to bearing particles when the bearing particles of metal oxide are disposed on a transparent electrode, and stability of the compound.

Examples of the phosphonic acid group include a methphosphonic acid group, an ethylphosphonic acid group, a propylphosphonic acid group, a hexylphosphonic acid group, an octylphosphonic acid group, a decylphosphonic acid group, a dodecylphosphonic acid group, an octadecylphosphonic acid group, a benzylphosphonic acid group, a phenylethylphosphonic acid group, a phenylpropylphosphonic acid group, and a biphenylphosphonic acid group.

Examples of the phosphoric acid group include a methylphosphoric acid group, an ethylphosphoric acid group, a propylphosphoric acid group, a hexylphosphoric acid group, an octylphosphoric acid group, a decylphosphoric acid group, a dodecylphosphoric acid group, an octadecylphosphoric acid group, a benzylphosphoric acid group, a phenylethylphosphoric acid group, a phenylpropylphosphoric acid group, and a biphenylphosphoric acid group.

Examples of the carboxyl group include a methylcarboxylic acid group, an ethylcarboxylic acid group, a propylcarboxylic acid group, a hexylcarboxylic acid group, an octylcarboxylic acid group, a decylcarboxylic acid group, a dodecylcarboxylic acid group, an octadecylcarboxylic acid group, a benzylcarboxylic acid group, a phenylethylcarboxylic acid group, a phenylpropylcarboxylic acid group, a biphenylcarboxylic acid group, a 4-propylphenylcarboxylic acid group, and a 4-propylbiphenylcarboxylic acid group.

Examples of the sulfonyl group include a methylsulfonyl group, an ethylsulfonyl group, a propylsulfonyl group, a hexylsulfonyl group, an octylsulfonyl group, a decylsulfonyl group, a dodecylsulfonyl group, an octadecylsulfonyl group, a benzylsulfonyl group, a phenylethylsulfonyl group, a phenylpropylsulfonyl group, and a biphenylsulfonyl group.

Examples of the silyl group include a methylsilyl group, an ethylsilyl group, a propylsilyl group, a hexylsilyl group, an octylsilyl group, a decylsilyl group, a dodecylsilyl group, an octadecylsilyl group, a benzylsilyl group, a phenylethylsilyl group, a phenylpropylsilyl group, and a biphenylsilyl group.

Examples of the silanol group include a methylsilanol group, an ethylsilanol group, a propylsilanol group, a hexylsilanol group, an octylsilanol group, a decylsilanol group, a dodecylsilanol group, an octadecylsilanol group, a benzylsilanol group, a phenylethylsilanol group, a phenylpropylsilanol group, and a biphenylsilanol group.

In General Formula (I), the ion X^- neutralizing the charge is a monovalent anion, and is not particularly limited as long as the ion can stable form a pair with a cation site. Examples of the ion X^- neutralizing the charge include Br ion (Br^-), Cl ion (Cl^-), I ion (I^-), OTf (triflate) ion (OTf^-), ClO₄ ion (ClO₄ ^-), PF₆ ion (PF₆ ^-), and BF₄ ion (BF₄ ^-).

The viologen compound is preferably a symmetric viologen compound having an alkyl chain of a certain length. In this case, in General Formula (I), m and n are each preferably from 4 through 10, and m and n are more preferably the same integer.

Specific exemplary compounds of the viologen compound are listed below, but the viologen compound is not limited to the following compounds.

<Conductive or semiconductive nanostructures>
The conductive or semiconductive nanostructures will be described.
The conductive or semiconductive nanostructures are preferably transparent.

In General Formula (I), at least one of R₁ to R₂ is a functional group that can be bonded to a hydroxyl group. For the bonding or adsorption structure of the viologen compound onto the conductive or semiconductive nanostructures, a phosphonic acid group, a sulfonic acid group, a phosphoric acid group, or a carboxyl group is used. In this case, the second electrochromic compound easily forms a complex with the nanostructures to become an electrochromic composite having excellent color image retention.

Two or more phosphonic acid groups, sulfonic acid groups, phosphoric acid groups, or carboxyl groups may be included in the viologen compound. When the viologen compound includes a silyl group or a silanol group, the viologen compound is bonded to each nanostructure via a siloxane bond to make a strong bond, and therefore a stable electrochromic composite can be obtained. The siloxane bond refers to a chemical bond via a silicon atom and an oxygen atom.

Moreover, the electrochromic composite is not particularly limited as long as the electrochromic composite has a structure where the viologen compound and the nanostructures are bonded via a siloxane bond. A bonding method and embodiment thereof are not particularly limited.

The conductive or semiconductive nanostructures are structures having nano-scale irregularities, such as nanoparticles, and porous nanostructures. A material constituting the conductive or semiconductive nanostructures is preferably metal oxide considering transparency and conductivity.

Examples of metal oxide include metal oxides each including, as a main component, 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, indium oxide, aluminosilicate, calcium phosphate, or aluminosilicate. The above-listed examples may be used alone or in combination. Among the above-listed examples, titanium oxide, zinc oxide, tin oxide, zirconium oxide, iron oxide, magnesium oxide, indium oxide, and tungsten oxide are preferable, and titanium oxide is more preferable, considering electrical properties, such as electrical conductivity, and physical properties, such as optical characteristics. Use of the metal oxide or a mixture of the metal oxides above achieves excellent response speed of coloring and decoloring.

A shape of the metal oxide is preferably metal oxide particles having the average primary particle diameter of 30 nm or less. As the average primary particle diameter thereof is smaller, light transmittance of the metal oxide increases, and the surface area (may be referred to as a “specific surface area” hereinafter) of the electrochromic composite per unit volume increases. Since the electrochromic composite has a large specific surface area, the second electrochromic compound is more efficiently carried on the conductive or semiconductive nanostructures, and multicolor display of an excellent display contrast ratio of coloring and decoloring can be realized.
The specific surface area of the electrochromic composite is not particularly limited and may be appropriately selected depending on the intended purpose. For example, the specific surface area thereof is preferably 100 m²/g or greater.

The average primary particle diameter of the metal oxide particles can be determined by observing randomly selected 100 metal oxide particles under a transmission electron microscope (TEM), determining a projected area of each particle, calculating a circle equivalent diameter of the obtained area to determine each particle diameter, and calculating an average value of the measured values to determine an average primary particle diameter of the metal oxide particles.

Examples of a formation method of the second electrochromic layer include vacuum vapor deposition, sputtering, and ion plating. When the materials of the second electrochromic layer can be applied to form a film by coating, various coating or printing methods can be used. Examples thereof include 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.

The average thickness of the second electrochromic layer is not particularly limited and may be appropriately selected depending on the intended purpose. The average thickness thereof is preferably 0.2 micrometers or greater but 5.0 micrometers or less. When the average thickness thereof is 0.2 micrometers or greater, high coloring density can be obtained. When the average thickness thereof is 5.0 micrometers or less, increase in the production cost can be suppressed, and reduction in visibility due to unintentional coloring can be prevented. The second electrochromic layer can be formed by vacuum film formation, but the second electrochromic layer is preferably formed by applying a particle dispersion paste by coating considering productivity.

<First support and second support>
The first support and second support have a function of supporting the first electrode, the first electrochromic layer, the second electrode, the second electrochromic layer, etc. Any of organic materials and inorganic materials known in the art may be used as the support as long as the material is a transparent material that can support the above-mentioned layers.

As the support, for example, a glass substrate, such as non-alkali glass, borosilicate glass, float glass, and soda-line glass, may be used. As the support, moreover, a resin substrate may be used. Examples of the resin substrate include a polycarbonate-based resin, an acryl-based resin, a polyethylene-based resin, a polyvinyl chloride-based resin, a polyester-based resin, an epoxy-based resin, a melamine-based resin, a phenol resin, a polyurethane-based resin, and a polyimide-based resin. Moreover, a surface of the support may be coated with a transparent insulation layer, a UV-cut layer, or an antireflection layer in order to enhance water-vapor barrier properties, gas barrier properties, UV resistance, or visibility.

A planar shape of the support is not particularly limited and may be appropriately selected depending on the intended purpose. For example, the shape thereof may be a rectangle or a circle. Two or more of the supports may be laminated. For example, the support having a structure where the electrochromic display element is sandwiched between two glass substrates can enhance water-vapor barrier properties and gas barrier properties.

<Other members>
Other members are not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a porous insulation layer, an antideterioration layer, and a protective layer.

-Porous insulation layer-
The porous insulation layer has a function of retaining the electrolyte, as well as separating the first electrode and the second electrode from each other to attain electrical insulation between the first electrode and the second electrode. A material of the porous insulation layer is not particularly limited, as long as the material is porous. The material is preferably an organic material, an inorganic material, or a composite of the organic material and the inorganic material, all of which have high insulating properties and durability and excellent film formability.

Examples of a formation method of the porous insulation layer include a sintering method (a method where polymer particles or inorganic particles are added to a binder to partially fuse the particles to utilize pores generated between the particles), an extraction method (a method where, after forming a constituting layer with an organic or inorganic material soluble in a solvent and a binder insoluble in the solvent, the organic or inorganic material is dissolved with the solvent to obtain pores), a foaming method where a coating liquid is foamed, a phase transformation method where a mixture of high-molecular-weight compounds are phase-separated by appropriately using a good solvent and a poor solvent, and a radiation method where pores are formed by applying various radial rays.

-Antideterioration layer-
The antideterioration layer has a role of performing a reverse chemical reaction to a reaction of the first electrochromic layer or second electrochromic layer to take a balance of charges. In this manner, it is possible to prevent corrosions or deteriorations caused by an irreversible redox reaction of the first electrode or second electrode. Note that, the reverse chemical reaction means functioning as a capacitor as well as a case where the antideterioration layer is oxidized or reduced.

A material of the antideterioration layer is not particularly limited and may be appropriately selected depending on the intended purpose, as long as the material is a material that prevents corrosions caused by an irreversible redox reaction of the first electrode or the second electrode. As the material of the antideterioration layer, for example, antimony tin oxide, nickel oxide, titanium oxide, zinc oxide, tin oxide, or conductive or semiconductive metal oxide containing two or more of the above-listed materials can be used. The antideterioration layer can be composed of a porous film that has a degree of porosity not to interfere an injection of the electrolyte. For example, a preferable porous film that permeates the electrolyte and functions as an antideterioration layer can be obtained by fixing conductive or semiconductive metal oxide particles (e.g., antimony tin oxide, nickel oxide, titanium oxide, zinc oxide, and tin oxide) on the second electrode with a binder (e.g., an acryl-based binder, an alkyd-based binder, an isocyanate-based binder, an urethane-based binder, an epoxy-based binder, and a phenol-based binder).

-Protective layer-
The protective layer is used for protecting the electrochromic element from external stress or chemicals used for washing processes, preventing leakage of the electrolyte, and preventing migration of substances (e.g., moisture and oxygen in the air) that are unnecessary for stable operations of the electrochromic element.

A material of the protective layer is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a UV-curable resin or heat-curable resin can be used. Specific examples thereof include an acrylic resin, a urethane-based resin, and an epoxy-based resin.

The average thickness of the protective layer is not particularly limited and may be appropriately selected depending on the intended purpose. The average thickness thereof is preferably 1 micrometer or greater but 200 micrometers or less.

<Production method of electrochromic element of first embodiment>
One example of the production method of the electrochromic element of the first embodiment will be described.

First, a display electrode 12 is formed on a first support 11. Then, a coating liquid (electrolytic liquid) that includes a first electrochromic composition including the electrochromic compound of the present disclosure, and one or a plurality of other radical polymerizable compounds is applied onto the display electrode 12. In this manner, a first laminate, in which the display electrode 12 and the first electrochromic layer 13 are sequentially formed on the first support 11, is produced.

The electrochromic compound and other radical polymerizable compounds for use are the same as ones described in the electrochromic element of the first embodiment.

The coating liquid is optionally diluted with a solvent to coat. The solvent is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include: alcohol-based solvents, such as methanol, ethanol, propanol, and butanol; ketone-based solvent, such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ester-based solvents, such as ethyl acetate, and butyl acetate; ether-based solvents, such as tetrahydrofuran, dioxane, and propyl ether; halogen-based solvents, such as dichloromethane, dichloroethane, trichloroethane, and chlorobenzene; aromatic solvents, such as benzene, toluene, and xylene; and cellosolve-based solvents, such as methyl cellosolve, ethyl cellosolve, and cellosolve acetate. The above-listed examples may be used alone or in combination.

The dilution rate with the solvent varies depending on dissolvability of the first electrochromic composition, a coating method for use, a thickness of the first electrochromic layer, etc. Thus, the dilution rate may be appropriately selected.

For example, the coating may be performed by dip coating, spray coating, bead coating, or ring coating.

Moreover, the production method of the electrochromic element of the present disclosure may include a step (polymerization or crosslinking step) including externally applying energy to the coated first electrochromic composition to polymerize or crosslink the first electrochromic composition.

In the polymerization or crosslinking step, after applying the first electrochromic composition onto the first electrode, energy is externally applied to the first electrochromic composition to cure the first electrochromic composition to thereby form a first electrochromic layer. Examples of the external energy include heat, light, and radial rays. A method for applying the heat energy is performed by heating the first electrochromic layer from the side of the coated surface or the side of the support using gas (e.g., air and nitrogen), vapor, various heat media, infrared rays, or electromagnetic waves.

The heating temperature is not particularly limited and may be appropriately selected depending on the intended purpose. The heating temperature is preferably from 60 degrees Celsius through 170 degrees Celsius. As the light energy, UV irradiation light sources mainly having emission wavelength in ultraviolet rays (UV), such as high-pressure mercury lamps, and metal halide lamps can be used. However, it is possible to use a visible light source matched to an absorption wavelength of a radical polymerizable group-containing compound or a photopolymerization initiator. The irradiation dose of UV is not particularly limited and may be appropriately selected depending on the intended purpose. The irradiation dose thereof is preferably from 5 mW/cm² through 15,000 mW/cm².

Next, a counter electrode 16 is formed on the second support 17. Thereafter, a coating liquid including an electrochromic composite, which includes the second electrochromic composition and conductive or semiconductive nanostructures, is applied onto the counter electrode 16. In this manner, a second laminate where the counter electrode 16 and the second electrochromic layer 15 are sequentially disposed on the second support 17 is produced.

As the second electrochromic composition and conductive or semiconductive nanostructures included in the electrochromic composite, any of the examples of the electrochromic composition and conductive or semiconductive nanostructures described in the first embodiment can be used.

Next, the electrolyte solution was applied between the first laminate and the second laminate to dispose an electrolyte layer 14A between the first laminate and the second laminate. In this manner, the electrochromic element 10A of the first embodiment is produced. In the case where the electrolyte constituting the electrolyte layer14A is curable by light or heat, curing is performed after bonding the first laminate and the second laminate via the electrolyte.

The production method of an electrochromic element of the first embodiment may further include other steps according to the necessity.

As other steps, for example, a step including forming a porous insulation layer on the first electrochromic layer 13 may be included when the electrochromic element 10A of the first embodiment includes the porous insulation layer. Moreover, the porous insulation layer may be formed on the bottom surface of the second electrochromic layer 15, or may be mixed with the electrolyte constituting the electrolyte layer 14A.

When the electrochromic element 10A of the present embodiment includes an antideterioration layer or a protective layer, moreover, the production method of the first embodiment may include a step including forming an antideterioration layer or a protective layer in the electrochromic element 10A of the first embodiment.

<Electrochromic element of second embodiment>
The electrochromic element of the second embodiment will be described. The electrochromic element 10B of the second embodiment is an embodiment identical to the electrochromic element 10A of the first embodiment in FIG. 1, except that the first electrochromic layer 13 and the second electrochromic layer 15 are not disposed. The electrochromic element 10B of the second embodiment uses an electrolyte layer including the electrochromic composition of the second embodiment instead of the electrolyte layer 14A of the electrochromic element 10A of the first embodiment.

FIG. 2 is a view illustrating one example of a structure of the electrochromic element of the second embodiment. The electrochromic element 10B of the second embodiment illustrated in FIG. 2 includes a first support 11, a display electrode 12, an electrolyte layer 14B, a counter electrode 16, and a second support 17, disposed in this order from the side of the first support 11. The electrolyte layer 14B includes the electrochromic composition of the present disclosure and an electrolyte. Since members constituting the electrochromic element 10B of the second embodiments are identical to the members constituting the electrochromic element 10A of the first embodiment, detailed descriptions thereof are omitted.

<Production method of electrochromic element of second embodiment>
One example of the production method of the electrochromic element of the second embodiment will be described. The production method of the electrochromic element of the second embodiment does not include the step for forming the first electrochromic layer 13 and the second electrochromic layer 15 of the electrochromic element 10A of the first embodiment illustrated in FIG. 1. The production method of the electrochromic element 10B of the second embodiment includes a step for forming an electrolyte layer 14B including the electrochromic composition of the present disclosure, instead of the electrolyte layer 14A.

Specifically, a display electrode 12 is formed on the first support 11. A counter electrode 16 is formed on the second support 17.

Next, an electrolyte solution including the electrochromic composition of the present disclosure and an electrolyte is prepared. Thereafter, the electrolyte solution is applied to fill the gap between the display electrode 12 and the counter electrode 16 to dispose the display electrode 12 and the counter electrode 16 to face via the electrolyte layer 14B. In the manner as described, the electrochromic element 10B of the second embodiment is produced.

<Use>
Since the electrochromic element of the present disclosure has excellent light fastness and durability against repetitive use, the electrochromic element of the present disclosure is suitably used, for example, for electrochromic displays, large display panels (e.g., stock and share price displays), anti-glare mirrors, and light-controlling elements (e.g., light-controlling glass). Moreover, the electrochromic element of the present disclosure is suitably used, for example, for low-voltage-driven elements (e.g., touch-panel key switches), photoswitches, photomemories, electronic paper, electronic albums, etc.

Examples

The present disclosure will be described below by way of Examples. The present disclosure should not be construed as being limited to these Examples.

In Examples below, reactions were tracked by TLC (Silica gel 60 F254, available from Merck KGaA).
Moreover, the following NMR and mass spectrometry were performed for determination of compounds.

NMR was performed by FT-NMR (ECX-500, available from JEOL Ltd., frequencies: (¹H NMR) 500 MHz, (¹³C NMR) 126 Hz, solvent: CDCl₃ (available from KANTO CHEMICAL CO., LTD. or Merck KGaA) and CD₂Cl₂ (available from Merck KGaA), TMS internal standard). The data was presented in the order of the chemical sift (coupling, J value, the number of protons). The abbreviations of coupling are as follows.
“s”: singlet, “d”: doublet, “t”: triplet, “q”: quartet, “dd”: doublet-doublet, “td”: triplet-doublet

The mass spectrometry (MS) was performed by MS (LCT-Premier, available from Waters, with an atmospheric solids analysis probe (ASAP) mode) and high resolution MS (HRMS, LTQ-XL Orbitrap, available from Thermo-scientific, with an ESI mode).

The IR spectroscopy was performed by a Fourier transform infrared (FTIR) spectrometer (measured by Spectrum 3 available from Perkin elmer with holding a sample with diamond cells (available from Sumitomo Electric Industries, Ltd.)). The main absorptions are presented with the wavelength (cm^-1).

A melting point (m.p.) was measured by means of a melting point measuring device (MP-J3, available from Anatec Yanaco Corporation).

(Example 1)
(Synthesis Example 1)
-Synthesis of Electrochromic Compound 1-
Electrochromic Compound 1 was synthesized according to the following scheme.

-Synthesis of Compound 1-1-
A 4-necked flask was charged with 3,6-di-tert-butylcarbazole (5.30 g, 19.0 mmol), methyl-2-iodobenzoate (available from Tokyo Chemical Industry Co., Ltd., 4.98 g, 19.0 mmol), copper (available from Merck KGaA, 408 mg, 6.42 mmol), copper iodide (available from KANTO CHEMICAL CO., LTD., 310 mg, 1.62 mmol), and potassium carbonate (available from KANTO CHEMICAL CO., LTD., powder, 3.8 g, 27.5 mmol), followed by argon gas purging. Thereafter, ortho-dichlorobenzene (available from KANTO CHEMICAL CO., LTD., 30 mL), which had been deaerated with argon gas, was added, followed by refluxing for 3 hours under a flow of argon gas. The resultant was returned to room temperature, and was then subjected to CELITE filtration, followed by washing the residues on the filter with chloroform. The combined organic layers were concentrated, to thereby obtain colorless solids. The obtained solids are recrystallized with ethanol, to thereby obtain Compound 1-1 as colorless crystals (yielded amount: 7.34 g, yield: 93.6%).

The spectrum data of Compound 1-1 is presented below. It was confirmed that the target structure was obtained.
¹H NMR (500 MHz, CDCl₃, δ) : 8.12 (dd, J₁= 2.0 Hz, J₂= 0.5 Hz, 2H), 8.07 (dd, J₁= 8.3 Hz, J₂= 2.0 Hz, 1H), 7.72 (td, J₁= 8.0 Hz, J₂= 1.5 Hz, 1H), 7.55 (t, J₁= 7.5 Hz, 2H), 7.41 (dd, J₁= 8.5 Hz, J₂= 2.0 Hz, 2H), 7.06 (dd, J₁= 9.0 Hz, J₂= 0.5 Hz, 2H), 3.22 (s, 3H, -COO-CH₃), 1.45 (s, 18H).

¹³C NMR (126 MHz, CDCl₃, δ) : 166.82 (C=O), 142.70, 140.11, 137.57, 133.29, 131.90, 129.99, 129.96, 127.92, 123.69, 123.37, 116.33, 108.77, 52.20 (-OCH₃), 34.81 (C-CH₃), 32.13 (-CH₃).

MS(ASAP)m/z: [M]⁺calculated for C₂₈H₃₁NO₂: 413.2355; found. 413.2660.

HRMS(ESI)m/z: [M+H]⁺calculated for C₂₈H₃₂NO_2:413.2433; found. 414.2420.

IR(neat): cm^-1 2962, 2903, 2868, 1720, 1598, 1580, 1492, 1475, 1456, 1393, 1365, 1327, 1294, 1251, 1191, 1169, 1127, 1097, 1085, 1075, 1046, 969, 876, 811, 796, 767, 741, 715, 615, 598, 418.

m.p.: 137.5 degrees Celsius

<Synthesis of Compound 1-2>
A 4-necked flask was purged with argon gas, and was charged with methylmagnesium iodide (available from Tokyo Chemical Industry Co., Ltd., 2M in Et₂O, 15 mL, 30 mmol). The methylmagnesium iodide in the flask was cooled to 0 degrees Celsius in an ice bath. To the flask, a solution obtained by dissolving Compound 1-1 (3.10 g, 7.50 mmol) in dehydrated toluene (available from KANTO CHEMICAL CO., LTD., 20 mL) was dripped over 10 minutes. The resultant was subjected to reflux for 3 hours under a flow of argon gas. The temperature thereof was returned to room temperature, and the contents in the flask were poured over ice cubes. To the resultant, a saturated ammonium chloride aqueous solution and ethyl acetate were added to separate the organic layer, and the aqueous layer was extracted 3 times with ethyl acetate. The combined organic layers were washed with a saturated saline solution, and were dried with sodium sulfate. The filtrate was concentrated, and the residues were purified by flash chromatography (silica gel, hexane/ethyl acetate), to thereby obtain Compound 1-2 as colorless solids (yielded amount: 2.90 g, yield: 93.5%).

The spectrum data of Compound 1-2 is presented below. It was confirmed that the target structure was obtained.

¹H NMR (500 MHz, CDCl₃, δ): 8.11 (dd, J₁= 1.5 Hz, J₂= 0.5 Hz, 2H), 7.89 (dd, J₁= 8.0 Hz, J₂= 1.5 Hz, 1H), 7.51 (td, J₁= 8.0 Hz, J₂= 1.5 Hz, 1H), 7.39 (dd, J₁= 8.5 Hz, J₂= 2.0 Hz, 2H), 7.34 (td, J₁= 8.0 Hz, J₂= 1.5 Hz, 1H), 6.91 (dd, J₁= 7.3 Hz, J₂= 1.5 Hz, 1H), 6.87 (dd, J₁= 8.5 Hz, J₂= 0.5 Hz, 2H), 2.16 (s, 1H, -OH), 1.44 (s, 24H, C-CH₃ and -CH₃).

¹³C NMR (126 MHz, CDCl₃, δ): 148.50, 142.92, 142.27, 135.79, 131.98, 129.25, 128.84, 127.44, 123.82, 116.26, 110.69, 34.82, 32.12, 31.67).

MS(ASAP) m/z: [M]⁺ calculated for C₂₉H₃₅NO: 413.2719; found. 413.3120.

HRMS(ESI) m/z: [M+H]⁺ calculated for C₂₉H₃₆NO: 414.2797; found. 414.2785.

IR (neat): cm^-1 3352, 2961, 2904, 2866, 1488, 1475, 1364, 1326, 1293, 1261, 1230, 1164, 1071, 878, 811, 764, 651, 625.

m.p.: 124 degrees Celsius

<Synthesis of Compound 1-3>
A recovery flask was charged with Compound 1-2 (1.46 g) and 85% phosphoric acid (available from KANTO CHEMICAL CO., LTD., 20 mL), and the resultant mixture was stirred for 4 hours at 100 degrees Celsius. After cooling the mixture to room temperature, the mixture was neutralized with a sodium hydroxide aqueous solution. To the resultant, ethyl acetate was added to separate the organic layer. The aqueous layer was extracted 3 times with ethyl acetate. The combined organic layers were washed with a saturated ammonium chloride aqueous solution, followed by washing with a saturated saline solution. The resultant was dried with sodium sulfate. The resultant was concentrated to obtain colorless amorphous. The obtained amorphous was purified by flash chromatography (silica gel, hexane/toluene), to thereby obtain Compound 1-3 as colorless solids (yielded amount: 362 mg, yield: 26%).

The spectrum data of Compound 1-3 is presented below. It was confirmed that the target structure was obtained.

¹H NMR (500 MHz, CDCl₃, δ): 8.12 (d, J₁= 1.5 Hz, 1H), 8.05 (dd, J₁= 8.0 Hz, J₂= 1.5 Hz, 2H), 7.89 (d, J = 2.0 Hz, 1H), 7.61 (dd, J₁= 8.0 Hz, J₂= 1.5 Hz, 1H), 7.57 (dd, J₁= 8.5 Hz, J₂= 2.0 Hz, 1H), 7.50 (d, J = 1.0 Hz, 1H), 7.33 (td, J₁= 7.3 Hz, J₂= 1.5 Hz, 1H), 7.13 (td, J₁= 7.5 Hz, J₂= 1.5 Hz, 1H), 1.73 (s, 6H, -C-CH₃), 1.48 (s, 18H, -C-(CH₃)₃).

¹³C NMR (126 MHz, CDCl₃, δ): 145.50, 143.68, 136.67, 136.36, 134.34, 128.67, 127.36, 127.08, 126.33, 123.85, 122.78, 121.74, 119.18, 117.19, 113.74, 113.61, 113.09, 37.03, 35.25, 34.80, 32.77, 32.24, 32.00.

MS(ASAP) m/z: [M]⁺ calculated for C₂₉H₃₃N: 395.2613 found. 395.3000.

HRMS(ESI) m/z: [M]⁺ calculated for C₂₉H₃₃N: 395.2613; found. 395.2602.

IR(neat): cm^-1 2962, 2869, 1604, 1580, 1498, 1472, 1456, 1411, 1392, 1364, 1341, 1321, 1299, 1283, 1248, 1235, 1201, 1108, 1063, 866, 750, 666, 645, 598.

m.p.: 163 degrees Celsius

<Synthesis of Compound 1-4>
A recovery flask was charged with Compound 1-3 (257 mg, 0.65 mmol), and dehydrated dimethyl formamide (available from Wako Pure Chemical Industries, Ltd., 6.5 mL), and the resultant mixture was cooled to 0 degrees Celsius in an ice bath. To the resultant, N-bromosuccinimide (121 mg, 0.683 mmol) was added little by little. After stirring the resultant mixture for 1 hour with shielding light, the mixture was returned to room temperature and stirred for 18 hours. To the resultant, a sodium thiosulfate aqueous solution was added to separate the organic layer. The aqueous layer was extracted 3 times with ethyl acetate, and the combined organic layers were washed with a sodium thiosulfate aqueous solution once, followed by washing with a saturated saline solution. The resultant was dried with sodium sulfate. The filtrate was concentrated, and the residues were purified by flash chromatography (silica gel, hexane/toluene), to thereby obtain Compound 1-4 as colorless solids (yielded amount: 230 mg, yield: 72%).

The spectrum data of Compound 1-4 is presented below. It was confirmed that the target structure was obtained.

¹H NMR (500 MHz, CDCl₃, δ): 8.12 (d, J₁= 2.0 Hz, 1H), 7.95 (dd, J₁= 8.5 Hz, 1H), 7.90 (d, J = 1.5 Hz, 1H), 7.89 (dd, J₁= 8.5 Hz, 1H), 7.68 (d, J = 2.0 Hz, 1H), 7.56 (dd, J₁= 8.5 Hz, J₂= 2.0 Hz, 1H), 7.48 (td, J = 1.5 Hz, 1H), 7.42 (dd, J₁= 8.5 Hz, J₂= 2.5 Hz, 1H), 1.71 (s, 6H), 1.48 (s, 18H).

¹³C NMR (126 MHz, CDCl₃, δ): 145.80, 144.02, 136.53, 136.34, 135.36, 134.11, 130.25, 129.78, 127.92, 126.33, 123.91, 121.78, 119.10, 117.22, 115.03, 113.76, 112.88, 37.19, 35.15, 34.71, 32.52, 32.07, 31.84.

MS(ASAP) m/z: [M]⁺ calculated for C₂₉H₃₂BrN: 473.1718; found. 473.3195.

HRMS(ESI) m/z: [M]⁺ calculated for C₂₉H₃₂BrN: 473.1718; found. 473.1705.

IR(neat): cm^-1 3037, 2963, 2868, 1595, 1573, 1494, 1456, 1406, 1390, 1363, 1321, 1297, 1281, 1250, 1236, 1202, 1137, 1113, 1093, 1061, 1027, 966, 939, 878, 868, 797, 746, 670, 642, 599, 461.

m.p.: 173 degrees Celsius

<Synthesis of Electrochromic Compound 1>
A 3-necked flask equipped with a nitrogen inlet tube and a reflux tube was charged with Compound 1-4 (145 mg, 0.31 mmol), palladium acetate (available from Tokyo Chemical Industry Co., Ltd., 14.1 mg, 20 mol% to halide), and tri(o-tolyl)phosphine (available from KANTO CHEMICAL CO., LTD., 78.0 mg, 40 mol% to halide), and was purged with argon gas.
To the resultant, dehydrated triethylamine (available from KANTO CHEMICAL CO., LTD., 3 mL), dehydrated toluene (available from KANTO CHEMICAL CO., LTD., 3 mL), and 4-methylstyrene (available from Tokyo Chemical Industry Co., Ltd., 52 microliters, 0.397 mmol). After bubbling the resultant mixture with argon gas, the resultant was subjected to reflux for 11 hours. The resultant was then subjected to CELITE filtration, and the residues on the filter were washed with ethyl acetate. The filtrate was concentrated, and the residues were purified by flash chromatography (silica gel, hexane/toluene), to thereby obtain Compound 1 as colorless solids (yielded amount: 89 mg, yield: 57%).

The spectrum data of Compound 1 is presented below. It was confirmed that the target structure was obtained.

¹H NMR (500 MHz, CDCl₃, δ): 8.13 (d, J₁= 1.5 Hz, 1H), 8.04 (dd, J = 9.0 Hz, 1H), 8.01 (d, J = 8.5 Hz, 1H), 7.90 (d, J = 1.5 Hz, 1H), 7.71 (d, J = 2.0 Hz, 1H), 7.58 (dd, J₁= 9.0 Hz, J₂= 2.0 Hz, 1H), 7.52 (d, J = 1.5 Hz, 1H), 7.50 (dd, J₁= 8.5 Hz, J₂= 2.0 Hz, 1H), 7.45 (d, J = 8.5 Hz, 2H), 7.18 (d, J = 7.5 Hz, 1H), 7.11 and 7.07 (AB quartet, J = 16.3 Hz, 2H), 2.37 (s, 3H, Ar-CH₃), 1.78 (s, 6H), 1.48 (s, 18H).

¹³C NMR (126 MHz, CDCl₃, δ): 145.53, 143.72, 137.17, 134.81, 131.91, 129.38, 128.50, 127.39, 126.85, 126.24, 125.71, 124.89, 123.80, 121.69, 119.18, 117.11, 113.90, 113.56, 112.93, 36.97, 35.14, 34.69, 32.86, 32.09, 31.87, 21.25.

MS(ASAP) m/z: [M]⁺ calculated for C₃₈H₄₁N: 511.3239; found. 511.3720.

HRMS(ESI) m/z: [M]⁺ calculated for C₃₈H₄₁N: 511.3239; found. 511.3230.

IR(neat): cm^-1 3026, 2961, 2869, 1603, 1557, 1512, 1489, 1456, 1408, 1362, 1341, 1320, 1277, 1247, 1203, 1112, 961, 890, 868, 853, 807, 730, 671, 659, 642, 595, 584, 508, 487, 452, 425.

m.p.: 227 degrees Celsius

(Example 2)
-Synthesis Example 2: Synthesis of Electrochromic Compound 2-
-Synthesis of Electrochromic Compound 2-
Compound 2 was synthesized in the same manner as Compound 1, except that 4-methoxystyrene was used instead of 4-methylstyrene. Compound 2 was obtained as colorless solids (yielded amount: 130 mg, yield: 59%).

The spectrum data of Compound 2 is presented below. It was confirmed that the target structure was obtained.

¹H NMR (500 MHz, CDCl₃, δ): 8.13 (d, J₁= 1.7 Hz, 1H), 8.04 (dd, J = 8.7 Hz, 1H), 8.01 (d, J = 8.6 Hz, 1H), 7.90 (d, J = 1.6 Hz, 1H), 7.70 (d, J = 2.0 Hz, 1H), 7.58 (dd, J₁= 8.8 Hz, J₂= 2.0 Hz, 1H), 7.51 (d, J = 1.7 Hz, 1H), 7.49 (d, J = 8.5 Hz, 3H), 7.05 and 7.03 (AB quartet, J = 16.3 Hz, 2H), 6.95-6.88 (m, 2H), 3.84 (s, 3H, Ar-OCH₃), 1.78 (s, 6H), 1.48 (s, 18H).

¹³C NMR (126 MHz, CDCl₃, δ): 159.10, 145.51, 143.69, 136.41, 134.47, 130.44, 127.51, 126.49, 126.35, 126.21, 125.56, 124.74, 123.79, 121.68, 119.18, 117.11, 14.14, 113.91, 113.56, 112.92, 55.33, 36.98, 36.98, 35.15, 34.70, 32.86, 32.10, 31.87.

MS(ASAP) m/z: [M]⁺ calculated for C₃₈H₄₁NO: 527.3188; found. 527.3763.

HRMS(ESI) m/z: [M]⁺ calculated for C₃₈H₄₁NO: 527.3188; found. 527.3182.

IR(neat): cm^-1 2961, 2905, 2868, 1608, 1512, 1497, 1456, 1408, 1362, 1339, 1321, 1279, 1252, 1203, 1177, 1031, 963, 868, 825, 808, 525, 453, 432, 422, 413.

m.p.: 198 degrees Celsius

(Example 3)
<Synthesis Example 3: Synthesis of Electrochromic Compound 3>
-Synthesis of Electrochromic Compound 3-
A 3-necked flask was charged with Compound 1-4 (145 mg, 0.31 mmol), triethylamine (2 mL), dioxane (available from KANTO CHEMICAL CO., LTD., 3 mL), and styrene (available from Tokyo Chemical Industry Co., Ltd., 1.8 eq, 0.55 mmol, 63 microliters). After bubbling the resultant solution with argon gas for 5 minutes, a trisdibenzylidene palladium-chloroform adduct (available from Aldrich, 2 mol%, 6.3 mg) and tri-tert-butylphosphonium tetrafluoroborate (6.8 mol%, 6 mg) were added, and the resultant mixture was subjected to reflux for 8 hours. The resultant was subjected to CELITE filtration, and the residues on the filter were washed with ethyl acetate. The filtrate was concentrated, and the residues were purified by flash chromatography (silica gel, hexane/toluene), to thereby obtain Compound 3 as colorless solids (yielded amount: 103 mg, yield: 68%).

The spectrum data of Compound 3 is presented below. It was confirmed that the target structure was obtained.

¹H NMR (500 MHz, CD₂Cl₂, δ): 8.16 (d, J = 1.7 Hz, 1H), 8.06 (d, J = 8.7 Hz, 1H), 8.04 (d, J = 8.6 Hz, 1H), 7.93 (d, J = 1.7 Hz, 1H), 7.78 (d, J = 2.0 Hz, 1H), 7.61 (dd, J₁= 8.8 Hz, J₂= 2.1 Hz, 1H), 7.57-7.54 (m, 4H), 7.38 (m, 2H), 7.26 (m, 1H), 7.19 and 7.13 (AB quartet, J = 16.3 Hz, 2H), 1.78 (s, 6H), 1.481 and 1.479 (s, 18H).

¹³C NMR (126 MHz, CDCl₃, δ): 146.127, 144.324, 138.048, 136.789, 136.036, 134.977, 134.462, 132.201, 129.111, 128.968, 128.615, 127.747, 127.203, 126.669, 126.574, 126.326, 125.496, 124.323, 122.100, 119.782, 117.579, 114.355, 114.069, 113.344, 37.352, 35.473, 35.015, 33.136, 32.230, 32.001.

MS(ASAP) m/z: [M]⁺ calculated for C₃₇H₃₉N: 497.3083; found. 497.3445.

HRMS(ESI) m/z: [M]⁺ calculated for C₃₇H₃₉N: 497.3083; found. 497.3075.

IR(neat): cm^-1 2962, 2905, 2868, 1596, 1499, 1456, 1408, 1393, 1364, 1338, 1322, 1281, 1264, 1247, 1203, 1114, 963, 868, 811, 805, 754, 740, 693.

m.p.: 223.5 degrees Celsius

(Example 4)
<Synthesis Example 4: Synthesis of Electrochromic Compound 4>
Electrochromic Compound 4 was synthesized according to the following scheme.

<Synthesis of Compound 4-1>
Synthesis was performed in the same manner as in Example 3 to obtain Compound 4-1 as colorless solids (100 mg, yield: 55%), except that the equivalent amount of 1-(4-chlorobutyl)-4-vinylbenzene was used instead of styrene.

The results of the mass spectrometry of Compound 4-1 are presented below. Since the error of the high resolution mass spectrometry was 4 ppm or less, it was confirmed that the target structure was obtained.

MS(ASAP) m/z: [M]⁺ calculated for C₄₀H₄₄ClN: 573.316; found. 573.286

HRMS(ESI) m/z: [M]⁺ calculated for C₄₀H₄₄ClN: 573.3162; found. 573.3140

<Synthesis of Compound 4>
A 4-necked flask was charged with Compound 4-1 (100 mg, 0.17 mmol), acrylic acid (available from Tokyo Chemical Industry Co., Ltd. (TCI), 115 mg, 1.6 mmol), potassium carbonate (available from KANTO CHEMICAL CO., LTD., powder, 3.7 g, 25.2 mmol), dehydrated dimethyl formamide (5 mL), and 2,6-ditert-butylcresol (0.1 mg), and the resultant mixture was heated at 85 degrees Celsius for 8.5 hours. The resultant solution was cooled to room temperature. To the solution, water and ethyl acetate were added to separate the organic layer. The aqueous layer was extracted 4 times with ethyl acetate. The combined organic layers were washed 3 times with water, followed by washing with saturated saline solution. The resultant was dried with anhydrous sodium sulfate. The desiccant was separated by filtration. The filtrate was vacuum concentrated, and the obtained residues were purified by silica gel-column chromatography (toluene/ethyl acetate). To the elute, 2,6-ditert-butylcresol (0.1 mg) was added. The resultant was vacuum concentrated, to thereby obtain Electrochromic Compound 4 as pale yellow amorphous solids (yielded amount: 91 mg, yield: 85%).

The results of the mass spectrometry of Compound 4 are presented below. Since the error of the high resolution mass spectrometry was 4 ppm or less, it was confirmed that the target structure was obtained.

MS(ASAP) m/z: [M]⁺ calculated for C₄₃H₄₇NO₂: 609.3607; found. 609.348

HRMS(ESI) m/z: [M]⁺ calculated for C₄₃H₄₇NO₂: 609.3607; found. 609.3592

(Example 5)
<Synthesis Example 5: Synthesis of Electrochromic Compound 5>
Electrochromic Compound 5 was synthesized according to the following scheme.

Synthesis was performed in the same manner as in Example 4 to thereby obtain Compound 5-1 as colorless solids, followed by obtaining Compound 5 as pale yellow amorphous solids (yielded amount: 91 mg, yield: 85%), except that 1-(3-chloropropoxy)-4-vinylbenzene was used instead of 1-(4-chlorobutyl)-4-vinylbenzene.

The results of the mass spectrometry of Compound 5 are presented below. Since the error of the high resolution mass spectrometry was 4 ppm or less, it was confirmed that the target structure was obtained.

MS(ASAP) m/z: [M]⁺ calculated for C₄₃H₄₇NO₃: 625.36; found. 625.37

HRMS(ESI) m/z: [M]⁺ calculated for C₄₃H₄₇NO₃: 625.3556; found. 625.3540

(Example 6)
-Spectroscopy for electrochemical characteristics of compound (measurement of absorption spectrum, fluorescence spectrum, and cyclic voltammetry)-
Each of Electrochromic Compounds 1 to 3 obtained in Examples 1 to 3, respectively, was dissolved in cyclohexane at 10^-5 M.
A measurement was performed by means of a visible-ultraviolet spectrophotometer (UH4150 UV/VIS/IR spectrophotometer, available from Hitachi high-tech science) in the range of from 200 nm to 800 nm.
With the same sample, a measurement of a fluorescence spectrum at the excitation wavelength of 330 nm was performed by means of a spectrofluorometer (Shimadzu RF-5000 spectrofluorometer, available from Shimadzu Corporation).
Moreover, an absolute fluorescence quantum yield was measured by means of an absolute fluorescence quantum yield measuring device equipped with an integrating sphere (C9920-02, excitation wavelength of Xe lamp (λmax): 330 nm, available from Hamamatsu Photonics K.K.) and a multi-channel spectrometer (Hamamatsu PMA-11, available from Hamamatsu Photonics K.K.). The results are presented in FIGs. 3 and 4 as absorption and fluorescence spectra. Moreover, the absorption peak wavelength, molar attenuation coefficient, and absolute fluorescence quantum yield are presented in Table 1. All the measurements were performed at room temperature, i.e., 25 degrees Celsius.
Subsequently, a sample, which was each of Electrochromic Compounds 1 to 3, was dissolved in a 0.1M tetrabutylammonium perchlorate (TBAP) dichloromethane solution at a concentration of 10^-3 M. The sample solution was subjected to cyclic voltammetry (3 cycles) at the sweeping speed of 50 mV/s by means of ALS-660C (available from BAS Inc.) with a triple electrode system including a working electrode (a platinum disk electrode, available from BAS Inc.), a counter electrode (a platinum wire), and a reference electrode (an Ag/Ag⁺ electrode, an acetonitrile solution of TBAP (0.1 M) and KNO₃ (0.01 M)). The results are presented in FIG. 5. Correction was made using 1/2 of redox potential of ferrocene under the same conditions, as the standard (Fc/Fc⁺). Repetitive stable redox behaviors were observed at from around 0 V through around 0.6 V based on the ferrocene standard. Electrochromic Compounds 1 to 3 had E_1/2ox of 0.45, 0.40, and 0.48 V (Vs Fc/Fc⁺), respectively, where E_1/2ox was half-wave potential of the redox.
Moreover, a constant current measurement was performed with monitoring a change in absorbance at from 300 nm through 900 nm by USB-4000 (available from Ocean Optics, Inc.) in the same manner as the CV, except that the working electrode was replaced with an ITO electrode (area: 2.0 cm²), to thereby determine color efficiency at the peak wavelength. The coloring efficiency is represented by a value obtained by dividing the absorbance change with the quantity of the applied current. The results are presented in Table 2.

Next, coloring efficiency and an absorption peak wavelength of each of Comparative Compounds 6-1 to 6-3 represented by the following structural formulae were measured in the same manner as in Electrochromic Compounds 1 to 3 of the present disclosure. The results are presented in Table 2.

Me denotes a methyl group.

It was found from the results in FIG. 3 and Table 1 that Electrochromic Compounds 1 to 3 of the present disclosure in the neutral state did not have almost any absorption in the visible range, and therefore high transparency could be expected when any of Electrochromic Compounds 1 to 3 would be used in an element. In addition, it was found from FIGs. 3 and 4 that the Stokes shift of the fluorescence spectrum was extremely small, and therefore it could be expected that a structural change in the excited state would be small. As a result, the fluorescence quantum yield, that was close to 80%, was exhibited.

It was found from the results in Table 2 that Electrochromic Compounds 1 to 3 exhibited high coloring efficiency compared to known triphenylamine of Comparative Compound 6-2, which caused one-electron oxidation. Compared to Comparative Compound 6-1 and Comparative Compound 6-3 (ethylviologen diperchlorate) that might cause two-electron oxidation and reduction, moreover, Electrochromic Compounds 1 to 3 exhibited similar coloring efficiency.

(Example 1-1)
<Production of first electrochromic element>
A production example of an electrochromic element of Example 1-1 will be described hereinafter.

-Formation of first electrochromic layer on first electrode-
A first electrochromic composition having the following composition was prepared for forming a first electrochromic layer on a first electrode.
<Composition>
Electrochromic Compound 1-1 including an acryloyl group (Exemplary Compound 1): 50 parts by mass
IRGACURE 184 (available from BASF Japan): 5 parts by mass
Polyethylene glycol including a diacryloyloxy group (“PEG400DA,” available from Nippon Kayaku Co., Ltd.): 50 parts by mass
Methyl ethyl ketone: 900 parts by mass

Next, the obtained first electrochromic composition was applied onto an ITO glass substrate (40 mm×40 mm, thickness: 0.7 mm, ITO film thickness: about 100 nm) serving as a first electrode by spin coating. The obtained coated film was irradiated with UV at 10 mW for 60 seconds by means of a UV irradiation device (SPOT CURE, available from USHIO INC.), followed by performing annealing at 60 degrees Celsius for 10 minutes, to thereby form a crosslinked first electrochromic layer having the average thickness of 400 micrometers.

-Formation of antideterioration layer on second electrode-
Next, a titanium oxide nano particle dispersion liquid (product name: SP210, available from SHOWA DENLO K.K., average particle diameter: about 20 nm) was applied as an antideterioration layer onto an ITO glass substrate (40 mm×40 mm, thickness: 0.7 mm, ITO film thickness: about 100 nm) serving as a second electrode by spin coating. Then, the coated film was annealed at 120 degrees Celsius for 15 minutes, to thereby form a nanostructure semiconductor material formed of a titanium oxide particle film having a thickness of 1.0 micrometer.

-Formation of second electrochromic layer on second electrode-
In order to form a second electrochromic layer on a second electrode, a second electrochromic composition having the following composition was prepared.
<Composition>
Electrochromic Compound 1-2 having a functional group that can be bonded to a hydroxyl group (Exemplary Compound A): 20 parts by mass
Tetrafluoropropanol: 980 parts by mass

The obtained second electrochromic composition was applied onto the nanostructure semiconductor material formed of the titanium oxide particle film on the second electrode by spin coating to allow the electrochromic compound in the second electrochromic composition to be adsorbed on the titanium oxide particles. Then, any excess part of the electrochromic compound, which was not adsorbed on the titanium oxide particles, was washed off with methanol, to thereby form a second electrochromic layer.

-Filling with electrolyte solution-
An electrolyte solution having the following composition was prepared.
<Composition>
IRGACURE184 (available from BASF Japan): 5 parts by mass
PEG400DA (available from Nippon Kayaku Co., Ltd.): 100 parts by mass
1-Ethyl-3-methylimidazolium tetracyanoborate (available from Merck KGaA): 50 parts by mass

The obtained electrolyte solution was collected by 30 mg with a micropipette, and the collected electrolyte solution was dripped onto the ITO glass substrate, serving as the second electrode, having the antideterioration layer and the second electrochromic layer. Onto the ITO glass substrate, the ITO glass substrate, serving as the first electrode, having the crosslinked first electrochromic layer, was bonded in a manner that drawing parts for the electrodes were secured, to thereby produce a bonded element. The bonded element was irradiated with UV (wavelength: 250 nm) by a UV irradiation device (SPOT CURE, available from USHIO INC.) at 10 mW for 60 seconds, to thereby produce an electrochromic element of Example 1-1.

<Coloring and decoloring operation>
Coloring and decoloring of the produced electrochromic element of Example 1-1 were confirmed. Voltage of ＋2.0 V was applied between the drawing part of the first electrode and the drawing part of the second electrode. As a result, coloring owing to Electrochromic Compound 1 of the first electrochromic layer was confirmed in the area where the first electrode layer and the second electrode layer were overlapped. Moreover, coloring owing to Electrochromic Compound 2 of the second electrochromic layer was confirmed. Subsequently, voltage of -0.5 V was applied between the drawing part of the first electrode and the drawing part of the second electrode for 5 seconds. As a result, it was confirmed that the area where the first electrode and the second electrode were overlapped was decolored and turned transparent.

The ultraviolet and visible absorption spectrum of the electrochromic element of Example 1-1 as colored is presented in FIG. 3. The absorption spectrum of FIG. 3 is an ultraviolet and visible absorption spectrum obtained by subtracting the ultraviolet visible absorption spectrum of Electrochromic Compound 1-2 as colored and the ultraviolet and visible absorption spectra of Electrochromic Compound 1-1 and Electrochromic Compound 1-2 as decolored from the ultraviolet and visible absorption spectrum of Electrochromic Compound 1-1 of the electrochromic element of Example 1 as colored. Specifically, the absorption spectrum of FIG. 3 only depicts the ultraviolet and visible absorption spectrum of Electrochromic Compound 1-1 (Exemplary Compound 1) as colored. In FIG. 3, the absorption spectrum in the wavelength range of from 380 nm through 780 nm is presented. As presented in FIG. 3, it was confirmed with naked eyes that Electrochromic Compound 1-1 (Exemplary Compound 1) colored in magenta.

(Examples 1-2 to 1-11)
Electrochromic elements of Examples 1-2 to 1-11 were each produced in the same manner as in Example 1-1, except that Exemplary Compound 1 used as Electrochromic Compound 1-1 was replaced with Exemplary Compounds 2 to 11.
It was confirmed that the electrochromic elements of Examples 1-2 to 1-11 also had the similar ultraviolet and visible absorption spectrum to that of the electrochromic element of Example 1-1. The ultraviolet and visible absorption spectrum of Electrochromic Compound 2 of Example 1-2 as colored is presented in FIG. 4. It was confirmed that Electrochromic Compound 2 also colored in magenta, similarly to Exemplary Compound 1.

(Comparative Examples 1-1 to 1-6)
Electrochromic elements of Comparative Examples 1-1 to 1-6 were each produced in the same manner as in Example 1-1, except that Exemplary Compound 1 used as Electrochromic Compound 1-1 was replaced with Comparative Compounds 1 to 6, respectively.
It was confirmed that the electrochromic elements of Comparative Examples 1-1 to 1-6 had the similar ultraviolet and visible absorption spectrum to that of the electrochromic element of Example 1-1.

The types and locations of the electrochromic compounds used in Examples 1-1 to 1-11 and Comparative Examples 1-1 to 1-6 are presented in Table 3.

<Evaluations>
Each of the produced electrochromic elements was subjected to a repeat test, and a coloring test in the following manner. The results are presented in Table 3.

Test 1-1: Durability test against repetitive use
Each of the produced electrochromic elements of Examples and Comparative Examples was tested. Voltage of 2.0 V was applied between the drawing part of the first electrode and the drawing part of second electrode for 5 seconds to color the electrochromic element, followed by applying voltage of －0.5 V between the drawing part of the first electrode and the drawing part of the second electrode for 5 seconds to decolor the electrochromic element, which was determined as 1 operation of coloring and decoloring. The coloring and decoloring operation was performed 500 times. The maximum absorbance in the visible region (380 nm to 780 nm) during the operations was determined as λmax. A change in the absorbance during the test was measured by means of USB4000 (available from Ocean Optics, Inc.), and the result was evaluated based on the following criteria.
<Evaluation criteria>
A: The absorbance of λmax was 95% or greater of the initial absorbance.
B: The absorbance of λmax was 90% or greater or less than 95% of the initial absorbance.
C: The absorbance of λmax was less than 90% of the initial absorbance.

Test 1-2: Coloring test
Each of the produced electrochromic elements of Examples and Comparative Examples was tested. After completing Test 1-1 above, voltage of ＋2.0 V was again applied, followed by confirming coloring with naked eyes. The result was evaluated based on the following evaluation criteria.
<Evaluation criteria>
I: No change was observed in coloring.
II: A slight change was observed in coloring.
III: A change was observed in coloring.

*EC: Exemplary Compound, CC: Comparative Compound
First: First electrochromic layer, Second: Second electrochromic layer
Third: Third electrochromic layer

It was confirmed from the results presented in Table 3 that the electrochromic elements of Examples 1-1 to 1-11 colored in magenta to red, and there was durability against repetitive use and no change in coloring after repetitive use.
In contrast, it was confirmed that the electrochromic elements of Comparative Examples 1-1 to 1-6 did not color in magenta, or could not achieve durability against repetitive use and no change in coloring after repetitive use.
Accordingly, it was found that the electrochromic composition according to the first embodiment contributed to realize an electrochromic element coloring excellent red and magenta, compared to materials known in the art.

(Example 2-1)
<Production of second electrochromic element>
Production example of an electrochromic element of Example 2-1 will be described below.

-Formation of spacer on first electrode-
An isopropanol solution of gap-controlling particles (average particle diameter: 80 micrometers, product name: Micropearl GS, available from SEKISUI CHEMICAL CO., LTD.) was applied onto an ITO glass substrate (40 mm × 40 mm, thickness: 0.7 mm, ITO film thickness: about 100 nm) serving as a first electrode, and the coated film was dried at 80 degrees Celsius for 3 minutes.

-Formation of antideterioration layer on second electrode-
Next, a titanium oxide nanoparticle dispersion liquid (product name: SP210, available from SHOWA DENLO K.K., average particle diameter: about 20 nm) was applied as an antideterioration layer onto an ITO glass substrate (40 mm×40 mm, thickness: 0.7 mm, ITO film thickness: about 100 nm) serving as a second electrode by spin coating. Then, the coated film was annealed at 120 degrees Celsius for 15 minutes, to thereby form a nanostructure semiconductor material formed of a titanium oxide particle film having a thickness of 1.0 micrometer.

-Bonding of substrates-
The ITO substrate serving as the first electrode and the ITO substrate serving as the second electrode were bonded in a manner that the first electrode and the second electrode were faced to each other, and the ITO substrates were arranged to be displaced by 5 mm from each other to leave drawing parts of the electrodes. Thereafter, the edge surfaces of the bonded element were coated with a sealing material (TB3050B, available from ThreeBond Holdings Co., Ltd.) except two inlets. The resultant bonded element was irradiated with UV (wavelength: 250 nm) by an UV irradiation device (SPOT CURE, available from USHIO INC.) at 10 mW for 60 seconds.

-Filling with electrolyte solution-
An electrolyte solution having the following composition was prepared.
<Composition>
Electrochromic Compound 2 (Exemplary Compound M1): 50 parts by mass
1-Ethyl-3-methylimidazolium bisfluorosulfonylimide (EMIM-FSI) (available from Merck KGaA): 100 parts by mass
N-methylpyrrolidone (NMP): 600 parts by mass

The obtained electrolyte solution was collected by 30 mg with a micropipette, and the collected electrolyte solution was injected into the cell from the inlets. The inlets were then sealed with the sealing material, followed by irradiating the cell with UV (wavelength: 250 nm) by an UV irradiation device (SPOT CURE, available from USHIO INC.) at 10 mW for 60 seconds. In the manner as described, an electrochromic element of Example 2-1, as illustrated in FIG. 6, was produced.

<Coloring and decoloring operation>
Coloring and decoloring of the produced electrochromic element of Example 2-1 were confirmed in the same manner as the confirmation method used for the electrochromic element of Example 1-1. As a result, coloring (magenta) owing to Electrochromic Compound 2 (Exemplary Compound M1) of the electrochromic layer was confirmed in the area where the first electrode and the second electrode were overlapped, when voltage of 2 V was applied between the drawing part of the first electrode and the drawing part of the second electrode for 5 seconds. Moreover, it was confirmed that, when voltage of －2 V was applied between the drawing part of the first electrode and the drawing part of the second electrode for 5 seconds, the area where the first electrode and the second electrode were overlapped was decolored and turned transparent.

(Examples 2-2 to 2-86)
Electrochromic elements of Examples 2-2 to 2-86 were each produced in the same manner as in Example 2-1, except that Exemplary Compound M1 used as Electrochromic Compound 2 was replaced with Exemplary Compounds M2 to M86, respectively.
Absorption spectra of the elements using Electrochromic Compound 2 (Exemplary Compounds M1, M2, and M3) of Examples 2-1, 2-2, and 2-3 are presented in FIG. 7. Moreover, the absorption spectra was standardized, and the standardized abruption spectrum in the range of from 380 nm through 780 nm, or from 400 nm through 780 nm was converted into transmittance. Moreover, tristimulus values (X, Y, and Z) were determined from a spectrum distribution and color-matching function (x, y, and z) of the standard illuminant (D65 light source), and each value of CIE L^*a^*b^* was determined from the calculated tristimulus values. Based on the obtained values of CIE L^*a^*b^*, CIE L^*a^*b^* was converted into L^*C^*h color space. The results (a^*, b^*, h) are presented in Table 5. In this color space system, h is arctan (b^*/a^*). Each of the standard values of Japan Color was obtained by measuring coat paper of Japan Color Standard by means of LCD panel evaluation device LCD5200 (available from Otsuka Electronics Co., Ltd.) with a D65 light source, and calculating values of L^*a^*b^* according to the above-described method. According to the standards of Japan Color, it is specified that a color should be measured with a D50 light source. It has been known that a value slightly sifts when a D65 light source is used for a measurement. Therefore, both values obtained using D50 and D65 light sources are presented.
Note that, values of the compound disclosed in Example 2-1 of Japanese Unexamined Patent Application Publication No. 2020-140053 (PTL 3) are also presented together.

(Comparative Examples 2-1 to 2-6)
Electrochromic elements of Comparative Examples 2-1 to 2-6 were each produced in the same manner as in Example 2-1, except that Exemplary Compound M1 used as Electrochromic Compound 1 was replaced by Comparative Compounds m1 to m6, respectively.
It was confirmed that the electrochromic elements of Comparative Examples 2-1 to 2-6 also colored owing to Electrochromic Compound 2, similarly to the electrochromic element of Example 2-1.

<Evaluations>
Each of the produced electrochromic elements was subjected to a continuous coloring test and a coloring test. The results are presented in Tables 4-1 and 4-2.

Test 2-1: Durability test against repetitive use
Each of the produced electrochromic elements of Examples and Comparative Examples was tested. Voltage of 2.0 V was applied between the drawing part of the first electrode and the drawing part of second electrode for 5 seconds, followed by applying voltage of －0.5 V between the drawing part of the first electrode and the drawing part of the second electrode for 5 seconds, which was determined as 1 operation of coloring and decoloring. The coloring and decoloring operation was performed 500 times. The maximum absorbance in the visible region (380 nm to 780 nm) during the operations was determined as λmax. A change in the absorbance during the test was measured by means of USB4000 (available from Ocean Optics, Inc.), and the result was evaluated based on the following criteria.
<Evaluation criteria>
A: The absorbance of λmax was 95% or greater of the initial absorbance.
B: The absorbance of λmax was 90% or greater or less than 95% of the initial absorbance.
C: The absorbance of λmax was less than 90% of the initial absorbance.

Test 2-2: Coloring test
Each of the produced electrochromic elements of Examples and Comparative Examples was tested. After completing Test 2-1 above, voltage of ＋2.0 V was again applied, followed by confirming coloring with naked eyes. The result was evaluated based on the following evaluation criteria.
<Evaluation criteria>
I: No change was observed in coloring.
II: A slight change was observed in coloring.
III: A change was observed in coloring.

In Table 4-1, “EC” stands for “Exemplary Compound”; e.g., EC M1 is Exemplary Compound M1.

In Table 4-2, “EC” stands for “Exemplary Compound”; e.g., “EC M48” is “Exemplary Compound M48”, and “CC” stands for “Comparative Compound”; e.g., “CC m1” is “Comparative Compound m1”.

It was confirmed from the results in Tables 4-1 and 4-2 that the electrochromic elements of Examples 2-1 to 2-86 colored in magenta to red, and there was durability against repetitive use and no change in coloring after repetitive use.
On the other hand, it was confirmed that the electrochromic elements of Comparative Examples 2-1 to 2-6 did not color in magenta, or durability against repetitive use and no change in coloring after repetitive use could not be achieved.
Compared between the standard values of magenta presented in Table 5 and the compound disclosed in Japanese Unexamined Patent Application Publication No. 2020-140053 (PTL 3), the compound (Exemplary Compound M 1) having higher reproducibility of magenta of Japan Color compared to the conventional material was obtained. The color is generally classified into “color of a light source” and “color of an object.” The color of the electrochromic element with which the remained light absorbed by the object is observed, unlike a self-emitting organic EL display, is preferably specified with the standard color of “color of object.” Japan Color is the standards for printing colors of offset printing in Japan. The expression of “color of object” is the closest to Japan Color.
Accordingly, the electrochromic compound according to the second embodiment contributed to realize an electrochromic element coloring in excellent red and magenta, compared to conventional materials.

For example, embodiments of the present disclosure are as follows.
<1> An electrochromic element including:
a first electrode;
a second electrode facing the first electrode with a space between the first electrode and the second electrode;
an electrolyte layer disposed between the first electrode and the second electrode; and
a layer including an electrochromic compound represented by General Formula (1) where the layer is disposed on or above the first electrode,

wherein, in General Formula (1), R₁ to R₂₂ are each a hydrogen atom, a halogen atom, an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an aryl group, a heteroaryl group, an amino group, a group represented by General Formula (2), or a polymerizable functional group including an acryloyl group, a methacryloyl group, an acryloyloxy group, or a methacryloyloxy group,
at least one selected from R₁, R₂, and R₁₅ is the group represented by General Formula (2), where R₁₆ to R₂₂ may be identical to or different from each other when a plurality of group represented by General Formula (2) are present, and
at least one selected from R₉ to R₁₄ forms a cyclic structure by bonding to a substituent on an adjacent benzene ring, or inserting a carbon atom, a silicon atom, an oxygen atom, a sulfur atom, or a selenium atom.
<2> An electrochromic element including:
a first electrode;
a second electrode facing the first electrode with a space between the first electrode and the second electrode; and
an electrolyte layer disposed between the first electrode and the second electrode,
wherein the electrolyte layer includes an electrochromic compound represented by General Formula (1),

wherein, in General Formula (1), R₁ to R₂₂ are each a hydrogen atom, a halogen atom, an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an aryl group, a heteroaryl group, an amino group, a group represented by General Formula (2), or a polymerizable functional group including an acryloyl group, a methacryloyl group, an acryloyloxy group, or a methacryloyloxy group,
at least one selected from R₁, R₂, and R₁₅ is the group represented by General Formula (2), where R₁₆ to R₂₂ may be identical to or different from each other when a plurality of group represented by General Formula (2) are present, and
at least one selected from R₉ to R₁₄ forms a cyclic structure by bonding to a substituent on an adjacent benzene ring, or inserting a carbon atom, a silicon atom, an oxygen atom, a sulfur atom, or a selenium atom.
<3> The electrochromic element according to <1> or <2>,
wherein R₁, R₂, and R₁₅ are all a halogen atom, an alkyl group, an alkoxy group, a group represented by General Formula (2), or a polymerizable functional group including an acryloyl group, a methacryloyl group, an acryloyloxy group, or a methacryloyloxy group.
<4> The electrochromic element according to any one of <1> to <3>,
wherein the number of the groups represented by General Formula (2) in R₁, R₂, and R₁₅ is 2 or less.
<5> The electrochromic element according to any one of <1> to <4>,
wherein two cyclic structures are formed among R₉ to R₁₄.
<6> The electrochromic element according to any one of <1> to <5>,
wherein the cyclic structure is bonded directly or bonded via a carbon atom or a silicon atom.
<7> The electrochromic element according to any one of <1> to <6>,
wherein at least one selected from R₁ to R₂₂ is a polymerizable functional group including an acryloyl group, a methacryloyl group, an acryloyloxy group, or a methacryloyloxy group.
<8> An electrochromic compound represented by General Formula (1),

wherein, in General Formula (1), R₁ to R₂₂ are each a hydrogen atom, a halogen atom, an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an aryl group, a heteroaryl group, an amino group, a group represented by General Formula (2), or a polymerizable functional group including an acryloyl group, a methacryloyl group, an acryloyloxy group, or a methacryloyloxy group,
at least one selected from R₁, R₂, and R₁₅ is the group represented by General Formula (2), where R₁₆ to R₂₂ may be identical to or different from each other when a plurality of groups represented by General Formula (2) are present, and
at least one selected from R₉ to R₁₄ forms a cyclic structure by bonding to a substituent on an adjacent benzene ring, or inserting a carbon atom, a silicon atom, an oxygen atom, a sulfur atom, or a selenium atom.
<9> The electrochromic compound according to <8>,
wherein R₁, R₂, and R₁₅ are all a halogen atom, an alkyl group, an alkoxy group, a group represented by General Formula (2), or a polymerizable functional group including an acryloyl group, a methacryloyl group, an acryloyloxy group, or a methacryloyloxy group.
<10> The electrochromic compound according to <8> or <9>,
wherein the number of the groups represented by General Formula (2) in R₁, R₂, and R₁₅ is 2 or less.
<11> The electrochromic compound according to any one of <8> to <10>,
wherein R₁, R₂, and R₁₅ are not a hydrogen atom.
<12> The electrochromic compound according to any one of <8> to <11>,
wherein two cyclic structures are formed among R₉ to R₁₄.
<13> The electrochromic compound according to any one of <8> to <12>,
wherein the cyclic structure is bonded directly or bonded via a carbon atom or a silicon atom.
<14> The electrochromic compound according to any one of <8> to <13>,
wherein at least one selected from R₁ to R₂₂ is a polymerizable functional group including an acryloyl group, a methacryloyl group, an acryloyloxy group, or a methacryloyloxy group.
<15> An electrochromic composition including
the electrochromic compound according to any one of <8> to <14>.
<16> The electrochromic composition according to <15>, further including
another radical polymerizable compound.
<17> The electrochromic composition according to <15> or <16>,
wherein the polymerizable functional group included in the electrochromic composition is polymerized or crosslinked.
<18> An electrochromic element including:
a first electrode;
a second electrode facing the first electrode with a space between the first electrode and the second electrode;
an electrolyte layer disposed between the first electrode and the second electrode; and
a layer including the electrochromic composition according to any one of <15> to <17>, where the layer is disposed on or above the first electrode.
<19> An electrochromic element including:
a first electrode;
a second electrode facing the first electrode with a space between the first electrode and the second electrode; and
an electrolyte layer disposed between the first electrode and the second electrode,
wherein the electrolyte layer includes the electrochromic composition according to any one of <15> to <17>.

The electrochromic element according to any one of <1> to <7>, <18>, and <19>, the electrochromic compound according to any one of <8> to <14>, and the electrochromic composition according to any one of <15> to <17> can solve the above-described various problems existing in the art and can achieve the object of the present disclosure.

Claims

An electrochromic element comprising:
a first electrode;
a second electrode facing the first electrode with a space between the first electrode and the second electrode;
an electrolyte layer disposed between the first electrode and the second electrode; and
a layer including an electrochromic compound represented by General Formula (1) where the layer is disposed on or above the first electrode,

wherein, in General Formula (1), R₁ to R₂₂ are each a hydrogen atom, a halogen atom, an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an aryl group, a heteroaryl group, an amino group, a group represented by General Formula (2), or a polymerizable functional group including an acryloyl group, a methacryloyl group, an acryloyloxy group, or a methacryloyloxy group,
at least one selected from R₁, R₂, and R₁₅ is the group represented by General Formula (2), where R₁₆ to R₂₂ may be identical to or different from each other when a plurality of groups represented by General Formula (2) are present, and
at least one selected from R₉ to R₁₄ forms a cyclic structure by bonding to a substituent on an adjacent benzene ring, or inserting a carbon atom, a silicon atom, an oxygen atom, a sulfur atom, or a selenium atom.
An electrochromic element comprising:
a first electrode;
a second electrode facing the first electrode with a space between the first electrode and the second electrode; and
an electrolyte layer disposed between the first electrode and the second electrode,
wherein the electrolyte layer includes an electrochromic compound represented by General Formula (1),

wherein, in General Formula (1), R₁ to R₂₂ are each a hydrogen atom, a halogen atom, an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an aryl group, a heteroaryl group, an amino group, a group represented by General Formula (2), or a polymerizable functional group including an acryloyl group, a methacryloyl group, an acryloyloxy group, or a methacryloyloxy group,
at least one selected from R₁, R₂, and R₁₅ is the group represented by General Formula (2), where R₁₆ to R₂₂ may be identical to or different from each other when a plurality of groups represented by General Formula (2) are present, and
at least one selected from R₉ to R₁₄ forms a cyclic structure by bonding to a substituent on an adjacent benzene ring, or inserting a carbon atom, a silicon atom, an oxygen atom, a sulfur atom, or a selenium atom.
The electrochromic element according to claim 1 or 2,
wherein R₁, R₂, and R₁₅ are all a halogen atom, an alkyl group, an alkoxy group, a group represented by General Formula (2), or a polymerizable functional group including an acryloyl group, a methacryloyl group, an acryloyloxy group, or a methacryloyloxy group.
The electrochromic element according to any one of claims 1 to 3,
wherein a number of the groups represented by General Formula (2) in R₁, R₂, and R₁₅ is 2 or less.
The electrochromic element according to any one of claims 1 to 4,
wherein two cyclic structures are formed among R₉ to R₁₄.
The electrochromic element according to any one of claims 1 to 5,
wherein the cyclic structure is bonded directly or bonded via a carbon atom or a silicon atom.
The electrochromic element according to any one of claims 1 to 6,
wherein at least one selected from R₁ to R₂₂ is a polymerizable functional group including an acryloyl group, a methacryloyl group, an acryloyloxy group, or a methacryloyloxy group.
An electrochromic compound represented by General Formula (1),

wherein, in General Formula (1), R₁ to R₂₂ are each a hydrogen atom, a halogen atom, an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an aryl group, a heteroaryl group, an amino group, a group represented by General Formula (2), or a polymerizable functional group including an acryloyl group, a methacryloyl group, an acryloyloxy group, or a methacryloyloxy group,
at least one selected from R₁, R₂, and R₁₅ is the group represented by General Formula (2), where R₁₆ to R₂₂ may be identical to or different from each other when a plurality of groups represented by General Formula (2) are present, and
at least one selected from R₉ to R₁₄ forms a cyclic structure by bonding to a substituent on an adjacent benzene ring, or inserting a carbon atom, a silicon atom, an oxygen atom, a sulfur atom, or a selenium atom.
The electrochromic compound according to claim 8,
wherein R₁, R₂, and R₁₅ are all a halogen atom, an alkyl group, an alkoxy group, a group represented by General Formula (2), or a polymerizable functional group including an acryloyl group, a methacryloyl group, an acryloyloxy group, or a methacryloyloxy group.
The electrochromic compound according to claim 8 or 9,
wherein a number of the groups represented by General Formula (2) in R₁, R₂, and R₁₅ is 2 or less.
The electrochromic compound according to any one of claims 8 to 10,
wherein R₁, R₂, and R₁₅ are not a hydrogen atom.
The electrochromic compound according to any one of claims 8 to 11,
wherein two cyclic structures are formed among R₉ to R₁₄.
The electrochromic compound according to any one of claims 8 to 12,
wherein the cyclic structure is bonded directly or bonded via a carbon atom or a silicon atom.
The electrochromic compound according to any one of claims 8 to 13,
wherein at least one selected from R₁ to R₂₂ is a polymerizable functional group including an acryloyl group, a methacryloyl group, an acryloyloxy group, or a methacryloyloxy group.
An electrochromic composition comprising
the electrochromic compound according to any one of claims 8 to 14.
The electrochromic composition according to claim 15, further comprising
another radical polymerizable compound.
The electrochromic composition according to claim 15 or 16,
wherein the polymerizable functional group included in the electrochromic composition is polymerized or crosslinked.
An electrochromic element comprising:
a first electrode;
a second electrode facing the first electrode with a space between the first electrode and the second electrode;
an electrolyte layer disposed between the first electrode and the second electrode; and
a layer including the electrochromic composition according to any one of claims 15 to 17, where the layer is disposed on or above the first electrode.
An electrochromic element comprising:
a first electrode;
a second electrode facing the first electrode with a space between the first electrode and the second electrode; and
an electrolyte layer disposed between the first electrode and the second electrode,
wherein the electrolyte layer includes the electrochromic composition according to any one of claims 15 to 17.