JP2008020519A - Electrochromic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrochromic device of cyan coloring capable of contributing to full-color image display and having high color purity. <P>SOLUTION: The electrochromic device is characterized in that: a pair of electrode structures on which transparent electrodes are formed are disposed facing each other through an electrolyte layer; a porous electrode adsorbing a pyridine compound expressed by formula (1) is formed on one of the transparent electrodes; and reversible coloring and decolorizing of cyan is carried out by applying a voltage between electrodes. In the formula, a and b represent integers satisfying a×b=2; X<SP>b-</SP>represents an anion having a valence of b; two of Y<SB>1</SB>, Y<SB>2</SB>, Y<SB>3</SB>, Y<SB>4</SB>are trifluoromethyl groups or cyano groups, and others in Y<SB>1</SB>, Y<SB>2</SB>Y<SB>3</SB>, Y<SB>4</SB>are hydrogen or aliphatic hydrocarbon groups; A<SB>1</SB>and A<SB>2</SB>represent aliphatic hydrocarbon groups or aromatic hydrocarbon groups which may be substituted and one of A<SB>1</SB>and A<SB>2</SB>has an adsorbing group to the porous electrode. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electrochromic device excellent in response speed, color development efficiency, display color purity, capable of forming a clear and sharp image and excellent in repeated durability.

In recent years, there has been a growing demand for display dye materials and display elements using the same that are bright and excellent in color purity, consume less power, and can be easily applied to full-color display. Conventionally, CRT, LCD, PDP Many proposals have been made on light-emitting elements such as ELD.
However, since the above-mentioned various conventional light-emitting elements are used in such a manner that the user looks directly at the light emission, there is a problem that visual fatigue is caused when browsing for a long time.
In addition, mobile devices such as mobile phones are often used outdoors, and there is also a problem that the visibility is deteriorated by canceling light emission under sunlight.
Furthermore, LCD is a technology that is especially in demand among light-emitting elements, and is used in various display applications such as large and small. However, LCD has a narrow viewing angle and is easy to see. There are issues to be improved.

By the way, regarding the reflective display element, various techniques have been proposed in the past due to an increase in demand for electronic paper. For example, a reflective LCD or an electrophoretic method can be used.
As the reflective LCD, a GH type liquid crystal system using a dichroic dye, a cholesteric liquid crystal, and the like are known. These have the advantage of power saving because they do not use a backlight as compared with conventional light emitting LCDs. However, they have a viewing angle dependency and low light reflection efficiency. There is a problem that the screen becomes dark.
On the other hand, the electrophoresis method is a method that utilizes a phenomenon in which charged particles dispersed in a solvent move by an electric field, and has the advantage of low power consumption and no viewing angle dependency. However, in the case of performing full color, it is necessary to apply a juxtaposed mixing method using a color filter, so that there is a problem that the reflectance is lowered and the screen is inevitably darkened.

In recent years, a device using an electrochromic (hereinafter abbreviated as EC) element has been proposed for a light control mirror, a timepiece or the like of an automobile.
Display using an EC element does not require a polarizing plate or the like, has no viewing angle dependency, has a color development type, has excellent visibility, has a simple structure and can be easily increased in size, and further varies depending on the selection of materials. There is an advantage that a color tone can be displayed.

  As a display device using an EC element, a proposal has been made for a display device having a structure in which a semiconductor nanoporous layer is formed on at least one of a pair of transparent electrodes and an EC dye is supported on the semiconductor nanoporous layer. (For example, refer to Patent Documents 1 and 2.) This display device can be held in a static state simply by configuring an open circuit to block the movement of electrons between the electrodes and maintaining the oxidation-reduction state, so no power is required to maintain the display image, and power consumption Is excellent in that it is extremely low.

JP 2003-248242 A JP 2003-270670 A

However, in the above-mentioned conventionally proposed technology, a bipyridine compound called viologen is used as a reactive dye, which performs blue color development and decoloration having a broad absorption wavelength width in the vicinity of a wavelength of 600 nm. In addition, since it has absorption even in the vicinity of a wavelength of 400 nm, it cannot be said that it is suitable for a display device for performing full-color display.
Regarding the EC dye that is optimal for so-called full-color development that develops in the required color tones of cyan (C), magenta (M), and yellow (Y) and has a sharp absorption width at a predetermined wavelength, it is still a technical disclosure. Has not been made.
In addition, the conventionally proposed display devices still have many problems in that the color purity is low and accurate and clear image display is performed.

Therefore, in the present invention, in view of the technical problems of the conventional EC element as described above, an organic EC dye capable of reversibly performing cyan decolorization as a dye that can contribute to full-color image formation. We decided to make a proposal on electrochromic devices using the.
Furthermore, by examining the chemical structure of the organic EC dye, it was decided to provide an electrochromic device having high color purity, capable of forming a clear image, and excellent in repeated durability.

  In the present invention, a pair of electrode structures in which at least a transparent electrode is formed on a support substrate are disposed with an electrolyte layer sandwiched so that the transparent electrodes face each other, and the pair of electrode structures A porous electrode on which a pyridine compound represented by the following general formula (1) is adsorbed is formed on at least one of the transparent electrodes constituting the electrode, and a voltage is applied between the pair of electrode structures. Thus, an electrochromic device capable of reversible cyan color reversal is provided.

However, in the general formula (1), a and b are integers satisfying a × b = 2, and X ^b− represents a b-valent anion.
At least two of Y ₁ , Y ₂ , Y ₃ and Y ₄ are a trifluoromethyl group or a cyano group, and Y ₁ , Y ₂ , Y ₃ and Y ₄ other than the above are hydrogen, aliphatic carbonization It is a hydrogen group.
A ₁ and A ₂ are an optionally substituted aliphatic hydrocarbon group or an aromatic hydrocarbon group, and at least one of A ₁ and A ₂ is an adsorption for adsorbing to the porous electrode. Has a group.

  According to the electrochromic device of the present invention, a clear cyan color tone that can contribute to full color can be stably displayed repeatedly many times, excellent in response speed and coloring efficiency, high color purity, and precise image control. Became possible.

The electrochromic device of the present invention will be specifically described with reference to the drawings.
However, the present invention is not limited to the following examples, and a conventionally known configuration can be added as appropriate, and does not depart from the gist of the present invention.

FIG. 1 shows a schematic sectional view of an example of the electrochromic device of the present invention.
The electrochromic device 10 includes a display electrode structure 11 having a configuration in which a transparent electrode 2 and a porous electrode 4 on which an organic EC dye 3 made of a pyridine compound described below is supported are supported on a support substrate 1, and a support substrate 6. Further, the counter electrode structure 12 having the configuration including the transparent electrode 7 and the porous electrode 8 is disposed so as to be opposed to each other with the electrolyte layer 5 interposed therebetween.
In FIG. 1, porous electrodes 4 and 8 are formed on both of the opposing transparent electrodes 2 and 7, but the present invention is not limited to this configuration, and only one electrode is necessary if necessary. A porous electrode may be formed, and the organic EC dye 3 may be supported on the porous electrode. Hereinafter, the components will be sequentially described.

The support substrates 1 and 6 are preferably made of a material having excellent heat resistance and high dimensional stability in the planar direction. Specifically, glass materials and transparent resins can be applied, but the present invention is not limited thereto. Absent.
Examples of the transparent resin include polyethylene terephthalate, polyethylene naphthalate, polyamide, polysulfone, polyether sulfone, polyether ether ketone, polyphenylene sulfide, polycarbonate, polyimide, polymethyl methacrylate, and polystyrene.

The transparent electrodes 2 and 7 are formed by laminating a transparent electrode layer on a predetermined transparent substrate.
Examples of the material for forming the transparent electrode layer include a mixture of In ₂ O ₃ and SnO ₂ , a so-called ITO film, and a film coated with SnO ₂ or In ₂ O ₃ .
Further, Sn, Sb, F, or the like may be doped into the ITO film or a film coated with SnO ₂ or In ₂ O ₃ , and other MgO, ZnO, or the like can be applied.

The porous electrodes 4 and 8 are made of a material having a large surface area in order to enhance the dye-supporting function described later.
Specifically, those having a mesoporous shape, aggregated particle shape, lot shape, wire shape or the like having fine pores on the surface and inside are preferable.
As the material of the porous electrodes 4 and 8, for example, a metal, an intrinsic semiconductor, an oxide semiconductor, a composite oxide semiconductor, an organic semiconductor, carbon, or the like can be applied.
Examples of the metal include Au, Ag, Pt, and Cu. Examples of the intrinsic semiconductor include Si, Ge, and Te. Examples of the oxide semiconductor include TiO ₂ , SnO ₂ , Fe ₂ O ₃ , SrTiO ₃ , WO ₃ , ZnO, ZrO ₂ , Ta ₂ O ₅ , Nb ₂ O ₅ , V ₂ O ₅ , In ₂ O ₃ , Examples thereof include CdO, MnO, CoO, TiSrO ₃ , KTiO ₃ , Cu ₂ O, sodium titanate, barium titanate, and potassium niobate. Examples of the complex oxide semiconductor include SnO ₂ —ZnO, Nb ₂ O ₅ —SrTiO ₃ , Nb ₂ O ₅ —Ta ₂ O ₅ , Nb ₂ O ₅ —ZrO ₂ , Nb ₂ O ₅ —TiO _2. , Ti—SnO ₂ , Zr—SnO ₂ , Sb—SnO ₂ , Bi—SnO ₂ , In—SnO _2, etc., and particularly TiO ₂ , SnO ₂ , Sb—SnO ₂ , and In—SnO ₂ are suitable. . Examples of the organic semiconductor include polythiophene, polypyrrole, polyacetylene, polyphenylene vinylene, and polyphenylene sulfide.

Next, the organic EC dye 3 will be described.
The organic EC dye 3 is assumed to be carried on the surface of the porous electrode 4 and the fine pores inside, and in the present invention, in particular, a pyridine compound represented by the following general formula (1) is applied.

However, in the general formula (1), a and b are integers satisfying a × b = 2, and X ^{b −} represents an appropriate b-valent anion. Fluorine ion, chlorine ion, bromine ion, iodine ion, perchlorate ion, periodate ion, hexafluorophosphate ion, hexafluoroantimonate ion, hexafluorostannate ion, phosphate ion, boron fluoride Inorganic acid ions such as hydrocyanic acid ions and tetrafluoroboric acid ions, thiocyanate ions, benzene sulfonate ions, naphthalene sulfonate ions, naphthalene disulfonate ions, p-toluene sulfonate ions, alkyl sulfonate ions, benzene carboxylic acids It is selected from organic acid ions such as ions, alkyl carboxylate ions, trihaloalkyl carboxylate ions, alkyl sulfate ions, trihaloalkyl sulfate ions, nicotinate ions, and tetracyanoquinodimethane ions.

At least two of Y ₁ , Y ₂ , Y ₃ and Y ₄ are a trifluoromethyl group or a cyano group.
A ₁ and A ₂ are an optionally substituted aliphatic hydrocarbon group or an aromatic hydrocarbon group, and at least one of A ₁ and A ₂ is an adsorbing group for adsorbing to the porous electrode. have. Specific examples of the adsorptive group include an acidic group such as a carboxyl group, a sulfonic acid group, and a phosphonic acid group, an amino group, a metal alkoxide, a metal halide, and the like, and a phosphonic acid group is particularly preferable.

  The pyridine compound of the organic EC dye represented by the general formula (1) includes, for example, a pyridine compound represented by the following general formula (2) and a halide represented by the following general formula (3) (especially bromide and iodide). Preferably) in a predetermined solvent or directly.

However, at least two of Y ₁ , Y ₂ , Y ₃ and Y ₄ in the general formula (2) are trifluoromethyl groups or cyano groups.

AX (3)
However, X shall be bromine or iodine.

  The compound represented by the general formula (2) includes, for example, a pyridine compound represented by the following general formula (4), (5) or (6) and a halide represented by the general formula (7) (particularly bromide, Iodide is preferred) by a coupling reaction in a suitable solvent in the presence of a palladium catalyst and a base.

However, in the above formula, at least two of Y ₁ , Y ₂ , Y ₃ and Y ₄ are a trifluoromethyl group or a cyano group.
However, X shows bromine or iodine.

  The compound represented by the above general formula (1) can synthesize all the structures having the functional groups shown in the proviso, and in any case, cyan coloration in the radical state, which is the object of the present invention, is possible. It was confirmed that there was.

With respect to the compound of the general formula (1), various compound characteristics such as color hue can be controlled by the types of substituents represented by Y ₁ , Y ₂ , Y ₃ , Y ₄ , A ₁ , A _2. It was confirmed that desired characteristics could be obtained by changing.
Specifically, with respect to Y ₁ , Y ₂ , Y ₃ , Y ₄ , the absorption wavelength shifts to the longer wavelength side by increasing the number of trifluoromethyl groups or cyano groups, and the color development is improved. Further, it was found that the trifluoromethyl group tends to obtain a steeper absorption wavelength peak.
Moreover, regarding A ₁ and A ₂ , it was found that there is a difference in display potential by selecting, for example, an alkyl chain or an aromatic ring. The display potential of the aromatic ring is lower, but in this regard, it is necessary to select it appropriately in consideration of the chemical structure of the dye and the optimum redox potential of the porous electrode to be adsorbed.

In general formula (1), it is expressed as divalent. However, when cyan coloring is performed, a reduction reaction results in a monovalent radical state.
At this time, the b-valent anion is appropriately released in the electrolyte according to its valence, or an ionic bond is formed with the proton of another organic EC dye compound so that electrical balance is obtained. Made.
This compound can be stabilized in this monovalent state, and it was confirmed that it is extremely excellent as an organic EC dye for cyan color development.
Specific examples of the bipyridine compound represented by the general formula (1) are shown below.

Next, a method for supporting the organic EC dye on the porous electrode 4 will be described.
For example, conventionally known techniques such as a method of adsorbing on the surface of the porous electrode 4 and a method of chemically bonding the surface of the porous electrode and the organic EC dye can be applied.
Specifically, a dry process such as a vacuum deposition method, a coating method such as spin coating, an electric field deposition method, an electric field polymerization method, a natural adsorption method in which a supported compound solution is immersed, and the like can be applied. A method of chemically bonding to the surface of the porous electrode with an organic EC dye adsorbing group is preferable.

As a natural adsorption method, a solution is prepared by dissolving a predetermined organic EC dye in a predetermined solvent, and a transparent substrate on which a porous electrode 4 that has been previously dried is formed is immersed, The method of apply | coating the solution which melt | dissolved organic EC pigment | dye to the porous electrode 4 is mentioned.
In this natural adsorption method, in order to reliably adsorb the organic EC dye to the porous electrode 4, it is necessary to introduce a functional group having adsorptivity into the chemical structure of the organic EC dye.
The functional group having adsorptivity is appropriately selected according to the material of the porous electrode 4. For example, when the porous electrode 4 is made of an oxide semiconductor, the adsorptive functional group in the chemical structure of the organic EC dye includes a phosphonic acid group, a sulfonic acid group, a carboxyl group, a hydroxy group, an amino group, etc. Is preferably introduced in advance.

  The adsorptive functional group may be introduced directly into the skeleton of the chemical structure of the organic EC dye, or may be introduced by forming a bond via another predetermined functional group. Among the above, when a predetermined functional group is used, an adsorptive functional group can be introduced through, for example, an alkyl group, a phenyl group, an ester, an amide group, or the like.

  Examples of the solvent for dissolving the organic EC dye include water, alcohol, acetonitrile, propionitrile, halogenated hydrocarbons, ethers, dimethyl sulfoxide, N, N-dimethylformamide, N-methylpyrrolidone, esters, Carbonates, ketones, hydrocarbons and the like can be applied. These may be used singly or may be mixed as appropriate.

Further, when the organic EC dye is chemically bonded to the surface of the porous electrode 4, a predetermined functional group may be interposed between the surface of the porous electrode 4 and the organic EC dye skeleton. For example, functional groups such as an alkyl group, a phenyl group, an ester, and an amide can be mentioned.
Further, after the surface of the porous electrode 4 is modified with a silane coupling agent or the like, an organic EC dye may be chemically bonded and formed.
When the organic EC dye forms a chemical bond with the material of the porous electrode 4 by such surface modification treatment of the porous electrode, the binding force of the organic EC dye becomes stronger. For example, the material of the electrolyte layer 5 As such, it is advantageous when a material having high dye solubility is used, the material selectivity of the organic dye is increased, and the durability of the electrochromic device is improved.

Although FIG. 1 shows an example in which the organic EC dye 3 is supported only on the porous electrode 4 on the display electrode structure 11 side, the electrochromic device of the present invention is not limited to this configuration. .
In other words, the porous electrode 8 on the counter electrode structure 12 side may be configured to carry a predetermined organic EC dye. In this case, it is necessary to select materials so that the coloring reaction and the decoloring reaction occur according to the reverse reaction of the oxidation reaction and the reduction reaction, respectively.
For example, when the pyridine dye supported on the porous electrode 4 becomes a radical state by the reduction reaction and develops color, the porous electrode 8 has the same color tone as the pyridine dye supported on the porous electrode 4 in a steady state. An organic EC dye that develops color by an oxidation reaction is selected.
As described above, by adopting a configuration in which the organic EC dye is supported in both the electrode structures 11 and 12, in the finally obtained electrochromic device, the color development can be clarified and the sharpness of the image can be improved. .

The electrolyte layer 5 has a configuration in which a supporting electrolyte is dissolved in a solvent.
Examples of the supporting electrolyte include lithium salts such as LiCl, LiBr, LiI, LiBF ₄ , LiClO ₄ , LiPF ₆ , and LiCF ₃ SO ₃ , potassium salts such as KCl, KI, and KBr, and NaCl, NaI, NaBr, and the like. And tetraalkylammonium salts such as tetraethylammonium borofluoride, tetraethylammonium perchlorate, tetrabutylammonium borofluoride, tetrabutylammonium perchlorate, and tetrabutylammonium halide.
A known redox compound may be added to the electrolyte layer 5 as necessary. As the redox substance, for example, a ferrocene derivative, a tetracyanoquinodimethane derivative, a benzoquinone derivative, a phenylenediamine derivative, or the like can be applied.
As the solvent, a solvent that dissolves the supporting electrolyte and does not dissolve the organic EC dye described above is selected.
For example, it is appropriately selected from water, acetonitrile, dimethylformamide, propylene carbonate, dimethyl sulfoxide, propylene carbonate and the like.

Further, a so-called matrix material may be applied to the electrolyte layer 5.
Matrix material can be appropriately selected depending on the purpose, for example, skeletal unit _{respectively, - (CC-O) n} -, - (CC (CH 3) -O) n -, - (CC-N ) _n- , or-(C-C-S) _n- , for example, polyethylene oxide, polypropylene oxide, polyethyleneimine, and polyethylene sulfide.
In addition, you may have a branched structure suitably by making these into a principal chain structure. Polymethyl methacrylate, polyvinylidene fluoride, polyvinylidene chloride, polycarbonate, and the like are also suitable.

The electrolyte layer 5 may be a polymer solid electrolyte layer.
In this case, it is preferable to add a predetermined plasticizer to the polymer of the matrix material.
As the plasticizer, when the matrix polymer is hydrophilic, water, ethyl alcohol, isopropyl alcohol, and a mixture thereof are preferable. When the matrix polymer is hydrophobic, propylene carbonate, dimethyl carbonate, ethylene carbonate, γ- Preferred are butyrolactone, acetonitrile, sulfolane, dimethoxyethane, ethyl alcohol, isopropyl alcohol, dimethylformamide, dimethyl sulfoxide, dimethylacetamide, n-methylpyrrolidone, and mixtures thereof.

Next, a display method using the electrochromic device 10 of the present invention will be described.
In the electrochromic device 10 of FIG. 1, the surface of the porous electrode 4 carries a pyridine compound represented by the general formula (1), which is an organic EC dye that does not absorb in the visible region in a steady state.
A predetermined lead wire is connected to the pair of electrode structures 11 and 12 constituting the electrochromic device 10 to constitute a display device.
When a predetermined voltage is applied through a predetermined lead wire, electrons are transferred between the porous electrode 4 and the organic EC dye material carried on the porous electrode 4, and an electrochemical reduction reaction occurs in the organic EC dye. It becomes a valent radical state and develops cyan. When a predetermined voltage is further applied, the organic EC dye returns to a steady state, and cyan reversible display can be performed by this reversible reaction.

Note that the electrochromic device of the present invention is not limited to the so-called monochromatic display configuration shown in FIG. 1, and can also be applied to a multicolor display configuration.
That is, an organic EC having the same structure as the electrochromic structure shown in FIG. 1 and having a radical state due to an electrochemical reaction and developing colors of magenta (M), cyan (C), and yellow (Y). By applying a dye and carrying it on a porous electrode to produce an electrode structure, and using these three layers, a laminated structure of magenta (M), yellow (Y), and cyan (C) is obtained. As a result, a full color display electrochromic device capable of reversibly performing color generation and decoloration display is obtained.

  Next, specific examples of the electrochromic device of the present invention and comparative examples will be described.

〔Example〕
Next, specific examples of the electrochromic device of the present invention and a comparative example thereof will be described.

(Organic EC dye compound: synthesis of the compound represented by the formula (8))
4- (4,4,5,5-tetramethyl-1,3,2-dioxaboran-2-yl) pyridine 2.21 g (10.8 mmol), 1,4-bis (trifluoromethyl) -2,5 -1.67 g (4.50 mmol) of dibromobenzene, 12 ml (1 M) of aqueous sodium carbonate solution, 0.158 g (0.255 mmo) of bis (triphenylphosphine) palladium (II) dichloride, 30 ml of dioxane, and 100 ° C. in the presence of argon. And stirred for 13 hours.
Water was added, and the formed precipitate was filtered and recrystallized with DMF to obtain white crystals.
0.20 g of the obtained white crystal was dissolved in 20 ml of DMF, 5 ml of diethyl bromoethylphosphonate was added, and the mixture was heated and stirred at 120 ° C. for 2 hours.
Acetone was added, and the resulting precipitate was filtered to obtain a white powder.
NMR analysis of the product confirmed that it was a compound represented by the formula (8).
The analysis results are shown below.
1H-NMR (DMSO) δ: 9.29 (4H, d, J = 6.3 Hz), 8.30 (6H, t, J = 13.0 Hz), 4.68-4.80 (4H, m, J = 7.2 Hz), 2.31-2.43 ( 4H, m, J = 7.3Hz).

(Organic EC dye compound: synthesis of the compound represented by the formula (12))
4- (4,4,5,5-tetramethyl-1,3,2-dioxaboran-2-yl) pyridine 2.21 g (10.8 mmol), 1,4-bis (trifluoromethyl) -2,5 -1.67 g (4.50 mmol) of dibromobenzene, 12 ml (1 M) of an aqueous sodium carbonate solution, 0.158 g (0.255 mmol) of bis (triphenylphosphine) palladium (II) dichloride and 30 ml of dioxane were added. The mixture was stirred at 13 ° C. for 13 hours.
Water was added, and the formed precipitate was filtered and recrystallized with DMF to obtain white crystals.
0.2 g of the obtained white crystals were dissolved in 10 ml of DMF, 5 ml of bromoethyl was added, and the mixture was heated and stirred at 140 ° C. for 24 hours.
The solvent was distilled off, acetone was added and filtered to obtain a pale yellow powder.
NMR analysis of the product confirmed that it was a compound represented by the formula (12).
The analysis results are shown below.
1H-NMR (DMSO) δ: 9.40 (4H, d, J = 6.8 Hz), 8.74 (2H, s), 8.60 (4H, d, J = 6.6 Hz), 4.76 (4H, q, J = 7.3 Hz) , 1.64 (6H, t, J = 7.3 Hz).

(Organic EC dye compound: synthesis of the compound represented by the formula (18))
Under N ₂ atmosphere, 1.72 g (8.4 mmol) of 4- (4,4,5,5-tetramethyl-1,3,2-dioxaboran-2-yl) pyridine, 1,4-dibromo-2,5 -Dicyanobenzene 1.0 g (3.5 mmol), sodium carbonate aqueous solution 9 ml (1 M), bis (triphenylphosphine) palladium (II) dichloride 0.139 g (0.198 mmol), and dioxane 23 ml were added, and 130 ° C. for 15 hours. Stir with heating.
After cooling to room temperature, the solution was filtered, the resulting powder was dissolved in hydrochloric acid, washed with ethyl acetate, the aqueous layer was made alkaline with sodium hydroxide, and the precipitate was filtered.
After washing with water and drying, a yellow powder was obtained.
0.2 g (0.71 mmol) of the obtained yellow powder was dissolved in 10 ml of DMF, 5 ml of diethyl bromoethylphosphonate was added, and the mixture was heated and stirred at 140 ° C. for 24 hours.
The solvent was distilled off, acetone was added and filtered to obtain a pale yellow powder.
NMR analysis of the product confirmed that it was a compound represented by the formula (18).
The analysis results are shown below.
1H-NMR (DMSO) δ: 9.40 (4H, d, J = 6.8 Hz), 8.74 (2H, s), 8.60 (4H, d, J = 6.6 Hz), 4.68-4.80 (4H, m, J = 7.2 Hz), 2.31-2.43 (4H, m, J = 7.3Hz).

  In addition to the above compounds, the same methods as the synthesis method described above are applied to the compounds represented by the formulas (9) to (11), formulas (13) to (17), and formulas (19) to (23) It was confirmed that it can be manufactured by.

(Preparation of display electrode structure)
On a support substrate 1 made of glass having a thickness of 1.1 mm, a 15 Ω / □ FTO film (transparent electrode 2) was formed in a plane.
Next, polyethylene glycol was dissolved at a rate of 5% by weight in a slurry in which 15% by weight of titanium oxide having a primary particle diameter of 20 nm was dispersed in an aqueous hydrochloric acid solution having a pH of about 1.0 to prepare a coating material. This paint was applied on the FTO film by a squeegee method.
Next, drying was performed at 80 ° C. for 15 minutes on a hot plate, and further sintering was performed at 500 ° C. for 1 hour in an electric furnace to obtain an FTO substrate on which a titanium oxide porous electrode 4 having a film thickness of 3 μm was formed. .

(Adsorption of organic EC dye to porous electrode)
The FTO substrate on which a porous electrode made of a titanium oxide film was formed was immersed in a 5 mM aqueous solution of each of the organic EC dye compounds prepared as described above for 24 hours to adsorb the organic EC dye on the titanium oxide electrode. Thereafter, washing treatment and drying treatment were performed with an ethanol solution.

(Preparation of counter electrode structure)
On a support substrate 6 made of glass having a thickness of 1.1 mm, a 15Ω / □ FTO film (transparent electrode 7) was formed in a plane.
Next, a coating material was prepared by dissolving polyethylene glycol at a ratio of 5% by weight in a slurry obtained by dispersing 20% by weight of antimony-doped tin oxide having a primary particle diameter of 20 nm in an acidic aqueous solution. This paint was applied on the FTO film by a squeegee method.
Next, an FTO substrate on which an antimony-doped tin oxide porous electrode 8 having a film thickness of 12 μm is formed by performing a drying treatment at 80 ° C. for 15 minutes on a hot plate and further sintering at 500 ° C. for 1 hour in an electric furnace. Obtained.

(Preparation of solution for electrolyte layer)
As the electrolyte layer 5 forming solution, a solution obtained by dissolving 0.1 mol / L of lithium perchlorate in gamma-butyrolaclone, dehydrating and degassing was applied.

(Lamination of electrode structure)
Adhesion of display electrode structure (substrate with dye-adsorbed titanium oxide porous electrode) and counter electrode structure (substrate with antimony-doped tin oxide porous electrode) produced as described above to a thermoplastic film having a thickness of 50 μm Using an agent, bonding was performed at 90 ° C.
At this time, an injection port was formed in a part so that the electrolyte solution could be injected by a process described later.

(Injection of electrolyte solution)
The electrolytic solution was injected from the injection port.
Thereafter, the injection port was sealed with an epoxy-based thermosetting resin, thereby completing an electrochromic device including electrode structures facing each other with the electrolyte layer sandwiched therebetween.
In accordance with the manufacturing process of the electrochromic device described above, different organic EC dyes supported on the porous electrode were applied to prepare sample cells of the following examples and comparative examples.

(Preparation of Example Sample)
As an organic EC dye, an electrochromic device in which the compounds of the above formulas (8), (12), and (18) were adsorbed on the porous electrode constituting the display electrode structure was used as a sample.

When a voltage of −1.5 V was applied between the display electrode and the counter electrode of the electrochromic device using the organic EC dye of the above formula (8), color was immediately developed to cyan.
FIG. 2 shows the spectrum during color development.
The response speed of the display change is about 150 ms, which is a sufficiently good speed for practical use.
Furthermore, when a voltage of 0.5 V was applied between the electrodes, it became transparent again immediately. The response speed of the display change was about 90 ms.
Further, when -1.5 V and 0.5 V were alternately applied 1 million times at 1 Hz between the display electrode and the counter electrode, the initial state and the spectral shape were maintained even after the voltage application was repeated 1 million times. Almost no change was observed, and it was confirmed that the material had sufficiently excellent durability for practical use.

When a voltage of −1.2 V was applied between the display electrode and the counter electrode of the electrochromic device using the organic EC dye of the above formula (12), the color was immediately developed to cyan.
FIG. 3 shows the spectrum during color development.
The response speed of the display change is about 120 ms, which is a sufficiently good speed for practical use.
Furthermore, when a voltage of 0.5 V was applied between the electrodes, it became transparent again immediately. The response speed of the display change was about 80 ms.
Further, when -1.2 V and 0.5 V were alternately applied 1 million times at 1 Hz between the display electrode and the counter electrode, the initial state and the spectral shape were maintained even after the voltage application was repeated 1 million times. Almost no change was observed, and it was confirmed that the material had sufficiently excellent durability for practical use.

When a voltage of −1.5 V was applied between the display electrode and the counter electrode of the electrochromic device using the organic EC dye of the formula (18), the color was immediately developed to cyan.
FIG. 4 shows the spectrum during color development.
The response speed of the display change is about 150 ms, which is a sufficiently good speed for practical use.
Furthermore, when 0.5 V was applied between the electrodes, it became transparent again immediately. The response speed of the display change was about 90 ms.
Further, when -1.5 V and 0.5 V were alternately applied 1 million times at 1 Hz between the display electrode and the counter electrode, the initial state and the spectral shape were maintained even after the voltage application was repeated 1 million times. Almost no change was observed, and it was confirmed that the material had sufficiently excellent durability for practical use.

  In the above examples, an electrochromic device was prepared by applying the organic EC dyes of the above formulas (8), (12), and (18). However, even when organic EC dyes represented by other formulas were applied, Similarly, by applying a predetermined voltage between the electrodes, it was confirmed that clear cyan reversible color display with an excellent response speed was possible.

  The compounds of the above formulas (8) to (23) are specific examples of organic EC dyes constituting the organic electrochromic device of the present invention, and the present invention is not limited thereto. In the organic electrochromic device of the present invention, various organic EC dyes having the structure of the general formula (1) can be appropriately selected according to the device configuration such as the electrode material and the electrode configuration.

In particular, a compound having two trifluoromethyl groups and having a structure in which a benzene ring is bonded to a pyridine ring, such as a compound of formula (12), forms a steep peak in the cyan color absorption wavelength. In addition, it was confirmed that the coloring potential can be kept low.
As shown in FIG. 4, the compound having two cyano groups like the compound of the formula (18) showed some absorption in the region of 450 to 500 nm, but the largest absorption peak in the vicinity of 650 nm. Therefore, practically good cyan coloration was obtained.

[Comparative example]
As the organic EC dye, a conventionally known organic EC dye represented by the following formula (24) was applied, and a sample of an electrochromic device was prepared in the same manner as in the above-described example, and the color development / decoloration evaluation was performed.

When a voltage of −1.5 V was applied between the display electrode and the counter electrode, blue color was exhibited. This color development spectrum is shown in FIG.
As is clear from FIG. 5, a peak having a wide absorption width was formed in the blue color development region, and it was confirmed that the color development required in the full color display element was not obtained. In addition, even when assuming a case where a large absorption peak is observed in the vicinity of 400 nm and a multicolor display device is manufactured by stacking electrochromic devices having the same configuration and different color development, Therefore, it was found that it was difficult to reliably control a single color, and it was unsuitable as a dye for full-color display.

  As is apparent from the above, according to the present invention, an extremely responsive reaction is achieved by applying the pyridine compound represented by the general formula (1) as the organic EC dye supported on the porous electrode constituting the electrode structure. It was possible to provide a cyan-colored electrochromic device that was excellent in color, sharp in color tone, and capable of stable reversible color-decolor display.

1 shows a schematic cross-sectional view of an example of an electrochromic device of the present invention. The visible absorption spectrum at the time of color development at the time of applying the compound of a formula (8) is shown. The visible absorption spectrum at the time of color development at the time of applying the compound of a formula (12) is shown. The visible absorption spectrum at the time of color development at the time of applying the compound of a formula (18) is shown. The visible absorption spectrum at the time of color development at the time of applying the compound of a formula (24) is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,6 ... Support substrate, 2 ... Transparent electrode, 3 ... Organic EC pigment | dye, 4,8 ... Porous electrode, 5 ... Electrolyte layer, 10 ... Electrochromic device, 11 ... Display electrode structure , 12 ... Counter electrode structure

Claims (2)

On the support substrate, a pair of electrode structures in which at least a transparent electrode is formed are arranged with an electrolyte layer sandwiched so that the transparent electrodes face each other,
On at least one of the transparent electrodes constituting the pair of electrode structures,
A porous electrode on which a pyridine compound represented by the following general formula (1) is adsorbed is formed,
An electrochromic device that performs reversible cyan coloration by applying a voltage between the pair of electrode structures.

However, in the general formula (1), a and b are integers satisfying a × b = 2, and X ^b− represents a b-valent anion.
At least two of Y ₁ , Y ₂ , Y ₃ and Y ₄ are a trifluoromethyl group or a cyano group, and Y ₁ , Y ₂ , Y ₃ and Y ₄ other than the above are hydrogen, aliphatic Consists of a hydrocarbon group.
A ₁ and A ₂ are an optionally substituted aliphatic hydrocarbon group or an aromatic hydrocarbon group, and at least one of A ₁ and A ₂ is an adsorption for adsorbing to the porous electrode. Has a group. 2. The electrochromic device according to claim 1, wherein the porous electrode is formed of a metal, a semiconductor material, or a conductive polymer having a mesoporous shape, an aggregated particle shape, a lot shape, or a wire shape.

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