JP2012093699A - Electrochromic element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrochromic element including combination with a macromolecular organic compound.SOLUTION: An electrochromic element includes an electrochromic layer and an electrolyte layer that are arranged between a pair of electrodes. The electrochromic layer includes a compound shown by the general formula and a macromolecular organic compound. Symbols A and A' in the general formula are selected from a hydrogen atom, an alkyl group and an aryl group; however, at least one of A and A' falls under the alkyl group or the aryl group, and symbols Rand Rtherein are each independently selected from a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an aryl group, an aralkyl group, a substituted amino group and a silyl group.

Description

  The present invention relates to an electrochromic device.

  An electrochromic element is an element having a function of adjusting the transmittance of visible light by oxidizing or reducing an electrochromic compound by application of a voltage. The case where the transmittance is high is called a decolored state, and the case where the transmittance is low is called a colored state.

  An electrochromic element has an electrochromic layer and an electrolyte layer between two electrodes. The electrochromic layer fades upon oxidation and reduction. The electrolyte layer exchanges ionic species with the electrochromic layer, thereby causing an oxidation reaction and a reduction reaction of the electrochromic layer.

  Patent Document 1 describes an electrochromic element having polyvinyl carbazole as a base material of an electrochromic layer and diheptyl viologen bromide as an electrochromic compound.

JP 2003-35914 A

K. L. Hoy, Journal of Paint Technology, 42, 76-118 (1970)

  It is known that an electrochromic element uses a polymer organic compound as a base material for an electrochromic layer. This is because when the electrochromic compound is a low molecule, it is difficult to form a layer by itself. That is, the high molecular organic compound is used to hold the electrochromic compound.

  However, depending on the combination of the polymer organic compound and the electrochromic compound, there is a problem that the transmittance of the electrochromic layer does not change sufficiently.

  For example, polyvinyl carbazole is used as a base material for an electrochromic layer because it has a high hole transport property and a high film property.

  However, since polyvinyl carbazole has a shallow HOMO (maximum occupied molecular orbital), it is difficult for holes to move from polyvinyl carbazole to an electrochromic compound.

  For this reason, there is a problem that the electrochromic compound is not sufficiently oxidized and the transmittance of the electrochromic compound does not change sufficiently.

Therefore, an object of the present invention is to provide an electrochromic device having a preferable combination of a polymer organic compound and an electrochromic compound.
Here, the shallow HOMO means that the HOMO level is closer to the vacuum level.

Therefore, the present invention
An electrochromic device having a pair of electrodes and an electrochromic layer and an electrolyte layer disposed between the pair of electrodes,
The ectrochromic layer provides an electrochromic device comprising an electrochromic compound represented by the following general formula [1] and a polymer organic compound.

  In the general formula [1], A and A ′ are each independently selected from a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, and an aryl group. However, at least one of A and A ′ is the alkyl group or the aryl group.

R ₁ and R ₂ are each independently selected from a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an aryl group, an aralkyl group, a substituted amino group, and a silyl group. .
The aryl group, the aralkyl group, the substituted amino group, and the silyl group selected as R ₁ and R ₂ may have an alkyl group having 1 to 4 carbon atoms as a substituent. n is 1 or 2.

  ADVANTAGE OF THE INVENTION According to this invention, the electrochromic element which has the high molecular organic compound which is a base material with high film property, and the novel electrochromic compound with good compatibility with it can be provided.

It is a cross-sectional schematic diagram of the electrochromic element which concerns on this embodiment.

The present invention is an electrochromic device having a pair of electrodes and an electrochromic layer and an electrolyte layer disposed between the pair of electrodes,
The ectrochromic layer is an electrochromic device comprising an electrochromic compound represented by the following general formula [1] and a high molecular organic compound.

  In the general formula [1], A and A ′ are each independently selected from a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, and an aryl group. However, at least one of A and A ′ is the alkyl group or the aryl group.

R ₁ and R ₂ are each independently selected from a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an aryl group, an aralkyl group, a substituted amino group, and a silyl group. .
The aryl group, the aralkyl group, the substituted amino group, and the silyl group selected as R ₁ and R ₂ may have an alkyl group having 1 to 4 carbon atoms as a substituent. n is 1 or 2.

R ₁ and R ₂ each independently represent a hydrogen atom, a halogen atom, or an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an aryl group, an aralkyl group, an amino group, or a silyl group. . n is 1 or 2.

  Examples of the alkyl group having 1 to 20 carbon atoms according to A and A ′ include methyl group, ethyl group, normal propyl group, isopropyl group, normal butyl group, tertiary butyl group, pentyl group, octyl group, dodecyl group, Examples include a cyclohexyl group, a bicyclooctyl group, an adamantyl group, and the like.

  Among these alkyl groups, those having a small number of carbon atoms are preferable, and a methyl group, an ethyl group, an isopropyl group, or a tertiary butyl group is preferable. More preferably, it is a methyl group, an ethyl group or an isopropyl group.

  Examples of the alkoxy group related to A and A ′ include a methoxy group, an ethoxy group, an octyloxy group, a decyloxy group, and the like.

  Examples of the aryl group according to A and A ′ include a phenyl group, a biphenyl group, a terphenyl group, a fluorenyl group, a naphthyl group, a fluoranthenyl group, an anthryl group, a phenanthryl group, a pyrenyl group, and a perylenyl group. Preferably, it is a phenyl group or a biphenyl group.

  The aryl group may further have a halogen atom, an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an aryl group, an aralkyl group, a substituted amino group, and a substituted silyl group. Groups. Specific examples of the alkyl group and aryl group are the same as the specific examples of the alkyl group and aryl group which are substituents introduced into A and A ′ described above. In the alkyl group, a hydrogen atom may be substituted with a fluorine atom.

At least one of A and A ′ is the alkyl group or the aryl group. This is because the dithienothiophene site serving as the light absorption site is sterically protected by at least one of A and A ′. Therefore, a phenyl group, a biphenyl group, an isopropyl group, a tertiary butyl group, and a dodecyl group are preferable because they are bulky. This is because when the dithienothiophene according to the present embodiment is in a radical cation state, the substituent is bulky, so that it is possible to suppress contact and reaction between another molecule and the dithienothiophene skeleton.
Moreover, this phenyl group and biphenyl group may have an alkyl group as a substituent.

  If one of A and A ′ is the alkyl group or the aryl group, the other may be a hydrogen atom.

Examples of the substituent related to R ₁ and R ₂ include the same alkyl groups and aryl groups as the specific examples of the alkyl group and aryl group that are substituents introduced into A and A ′ described above. Other examples of the substituents related to R ₁ and R ₂ include alkoxy groups such as methoxy group, ethoxy group, octyloxy group and decyloxy group, aralkyl groups such as benzyl group and phenylethyl group, dimethylamino group, diphenylamino group and the like. Examples thereof include substituted silyl groups such as a substituted amino group, trimethylsilyl group, and triisopropylsilyl group.

  These substituents have an effect of increasing the electron density of the dithienothiophene moiety of the compound represented by the general formula [1]. Oxidation potential is lowered by electron donation of the substituent, and there is an effect of lowering the driving voltage when used in an electrochromic device. In particular, a methyl group, an ethyl group, a methoxy group, and a dimethylamino group are preferable.

Moreover, it is preferable that the substituent which concerns on these R < ₁ > and R < ₂ > is substituted by the para position of the phenyl group couple | bonded with a dithienothiophene site | part. This is to suppress side reactions such as electrolytic polymerization accompanying redox.

  Examples of the polymer organic compound included in the electrochromic device according to this embodiment include polyvinyl carbazole, poly (t-butyl acrylate), poly (methyl methacrylate), and polystyrene. These may be used alone or mixed.

  Polyvinylcarbazole is used for electrochromic devices because of its high film properties and high hole transportability.

  A comparison between dithienothiophene, which is the basic skeleton of the electrochromic compound according to the present embodiment, and 1,10-phenanthroline used as the electrochromic compound will be described below.

  Here, the basic skeleton indicates only the condensed ring structure in the structural formula.

  The structural formula of 1,10-phenanthroline is shown below. Hereinafter, 1,10-phenanthroline is simply referred to as phenanthroline.

  When considering the movement of holes, focus on the highest occupied orbit (HOMO) of molecules.

Table 1 shows a comparison of HOMO values of polyvinylcarbazole, phenanthroline, and dithienothiophene. Phenanthroline is listed as an example of an electrochromic compound.
The energy level of HOMO was calculated using molecular orbital calculation.

  Molecular orbital calculation is performed using Gaussian 03 (Gaussian 03, Revision D.01, MJ Frisch, GW Trucks, H. B. Schlegel, GE Scuseria, MA Robbb, which is currently widely used. , JR Cheeseman, JA Montgomery, Jr., T. Vreven, K. N. Kudin, J. C. Burant, J. M. Millam, S. S. Iyengar, J. Tomasi, V. Barone, B. Mennucci, M. Cossi, G. Scalmani, N. Rega, GA Petersson, H. Nakatsuji, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa, J. Hasegawa. Ishida, T Nakajima, Y. Honda, O. Kitao, H. Nakai, M. Klene, X. Li, J. E. Knox, H. P. Hratchian, J. B. Cross, V. Bakken, C. Adamo, J. Jaramillo, R. Gomperts, R. E. Stratmann, O. Yaziev, A. J. Austin, R. Cammi, C. Pomelli, J. W. Octerski, P. Y. Ayala, K. Morokuma, G.A. Voth, P. Salvador, JJ Dannenberg, VG Zakrzewski, S. Daprich, AD Daniels, MC Strain, O. Farkas, DK Malick, AD Rabuck , K. Rachavach ri, JB Foresman, JV Ortiz, Q. Cui, AG Baboul, S. Clifford, J. Cioslowski, BB Stefanov, G. Liu, A. Liashenko, P. Piskov, I. Komaromi, RL Martin, D.J. Fox, T. Keith, MA Al-Laham, CY Peng, A. Nanayakara, M. Challacombe, P.M.W.Gill, B. Johnson, W. Chen, MW Wong, C. Gonzalez, and JA Popple, Gaussian, Inc., Wallingford CT, 2004). Was used to calculate the DFT basis function 6-31G (d). Although this calculation method is known to contain extremely small errors with respect to the actually measured values, it is a useful calculation method for molecular design and for comparing other compounds relative to each other.

  The molecular weight of polyvinyl carbazole is preferably 10,000 or more. This is to maintain the film properties of polyvinyl carbazole. Since HOMO of polyvinylcarbazole shows a substantially constant value regardless of the molecular weight, the value of HOMO may be considered as it is in the table.

  Further, dithienothiophene is easily expected to have a deeper HOMO than the electrochromic compound according to the present embodiment. That is, it can be expected that the HOMO becomes shallower in the order of phenanthroline, dithienothiophene, and the electrochromic compound according to the present embodiment.

  When the calculated values shown in Table 1 are compared, phenanthroline has a HOMO value of 0.93 eV deeper than polyvinylcarbazole. Since this difference becomes an energy barrier, the movement of holes from polyvinylcarbazole to phenanthroline is difficult and needs to be improved.

  In contrast, the difference in the HOMO value between polyvinylcarbazole and dithienothiophene is 0.28 eV. That is, dithienothiophene is more likely to receive holes from polyvinylcarbazole than phenanthroline.

  Then, it turns out that the electrochromic compound which concerns on this embodiment tends to receive a hole from polyvinyl carbazole.

  Therefore, in the electrochromic device having polyvinyl carbazole and dithienothiophene in the electrochromic layer, more holes are supplied to the exemplary compound A-1 than phenanthroline, so that an unreacted compound hardly remains. Therefore, the electrochromic element obtains high transmittance. High transmittance means that the transmittance of light having a wavelength of 360 nm or more and 830 nm or less is high. The transmittance is preferably 70% or more.

  In addition to Exemplified Compound A-1, the compound represented by the general formula [1] has a shallower HOMO than phenanthroline, and thus an electrochromic device having the compound can obtain high transmittance.

  In the electrochromic compound according to this embodiment, the repeating unit n of dithienothiophene is 1 or 2. When n is 3 or more, a light absorption region in the visible light region appears. When n is 1 or 2, since there is no absorption in the visible light region, high transparency is exhibited in an electrically neutral state.

  Next, an example using the electrochromic compound according to the present embodiment and a high molecular organic compound as a base material will be described.

The electrochromic compound and a polymer organic compound according to the present embodiment, the solubility parameter of the polymer is larger and the difference between the solubility parameters of the electrochromic compound 0,17 (cal ^1/2 cm ^-3/2) It is preferable that the relationship is 0.68 (cal ^1/2 cm ^−3/2 ) or less. Hereinafter, the basis will be described in detail.

When the solubility parameter δ (cal ^1/2 cm ^{−3 /} 2) is calculated by the Hoy method described in Non-Patent Document 2, the compound of the following compound A is 9.93 (cal ^1/2 cm ^−3/2). ), Compound of Exemplified Compound A-17 is 8.25 (cal ^1/2 cm ^−3/2 ), t-butyl polyacrylate is 8.42 (cal ^1/2 cm ^−3/2 ), and polystyrene is 8 .92 (cal ^1/2 cm ^−3/2 ), polymethyl methacrylate is 9.44 (cal ^1/2 cm ^−3/2 ), and polyvinylcarbazole is 10.1 (cal ^1/2 cm ^−3/2). )

In the Hoy method, the solubility parameter δ is set to δ = (density) (gcm ⁻³ ) × (sum of molar attraction constant) (cal ^1/2 cm ^3/2 mol ⁻¹ ) / (molecular weight) (gmol ⁻¹ ). For polymers, the value of monomer is used for (molecular weight). The molar attractive force constant is determined for each atomic group or functional group, and a value is described in Table 4 of Non-Patent Document 2. The calculation process is shown below.

<Compound A>
(Density) = 1.20 (gcm ⁻³ ), (Molecular weight) = 196 (gmol ⁻¹ ), (Sum of molar attraction constants) = 117.12 × 4 + 98.12 × 4 + 20.99 × 3 + 209.42 × 3 = 1621.97 (cal ^{1 / 2} cm ^3/2 mol ⁻¹ ), and δ = 1.2 × 162.97 / 196 = 9.93 (cal ^1/2 cm ^−3/2 )
<Exemplary Compound A-17>
(Density) = 1.15 (gcm ⁻³ ), (Molecular weight) = 432 (gmol ⁻¹ ), (Sum of molar attraction constants) = 117.12 × 2 + 98.12 × 6 + 20.99 × 3 + 23.26 × 3 + 148.3 × 6 + 117.12 × 4 + 98.12 × 8 + 23.26 × 2 + (−23.44) × 2
= 3098.59 (cal ^1/2 cm ^3/2 mol ⁻¹ ), and δ = 1.15 × 3098.59 / 432 = 8.25 (cal ^1/2 cm ^−3/2 )
<T-butyl polyacrylate>
(Density) = 1.09 (gcm ⁻³ ), (Molecular weight) = 128 (gmol ⁻¹ ), (Sum of molar attraction constants) = 148.3 × 3 + 326.58 × ¹ + 85.99 × ¹ + 131.5 × ¹ = 988.97 (cal ^{1 / 2} cm ^3/2 ), and δ = 1.09 × 988.97 / 128 = 8.42 (cal ^1/2 cm ^−3/2 )
<Polystyrene>
(Density) = 1.03 (gcm ⁻³ ), (Molecular weight) = 104 (gmol ⁻¹ ), (Sum of molar attraction constants) = 85.99 × 1 + 131.5 × 1 + 117.12 × 5 + 98.12 × 1 + 23.26 × 1 + (− 23.44) x1 = 901.03 (cal ^1/2 cm ^3/2 ) and δ = 1.03 × 901.03 / 104 = 8.92 (cal ^1/2 cm ^−3/2 )
<Polymethyl methacrylate>
(Density) = 1.20 (gcm ⁻³ ), (Molecular weight) = 100 (gmol ⁻¹ ), (Sum of molar attraction constants) = 148.3 × 2 + 326.58 × ¹ + 32.03 × ¹ + 131.5 × ¹ = 786.71 (cal ^{1 / 2} cm ^3/2 ), and δ = 1.20 × 786.71 / 100 = 9.44 (cal ^1/2 cm ^−3/2 )
<Polyvinylcarbazole>
(Density) = 1.20 (gcm ⁻³ ), (Molecular weight) = 193 (gmol ⁻¹ ), (Sum of molar attraction constants) = 85.99 × 1 + 131.5 × 1 + 117.12 × 8 + 98.12 × 4 + 61.08 × 1 + 23.26 × 2 + (− 23. 44) x2 + 20.99x1 = 1628.64 (cal ^1/2 cm ^3/2 ), and δ = 1.20x162.64 / 193 = 10.1 (cal ^1/2 cm ^−3/2 )

Difference δ _P between solubility parameter δ _EC (cal ^1/2 cm ^−3/2 ) of compound A or exemplary compound A-17 and solubility parameter δ _P (cal ^1/2 cm ^−3/2 ) of various polymers −δ _EC (cal ^1/2 cm ^−3/2 ) was calculated. The results are shown in Table 2.

The numerical value in () is the value of the solubility parameter of the compound and polymer. For example, the combination of Compound A and polyacrylic acid t- butyl, is calculated as ^{_{δ P -δ EC = 8.42-9.93 = -1.51}} (cal 1/2 cm -3/2).

The solubility parameter is used as an index of compatibility between different materials. The smaller the solubility parameter difference, the higher the compatibility between different materials.

Therefore, a mixture having a large value of δ _P -δ _EC is not compatible with each other, so that the transmittance is low, and a mixture having a small value of δ _P -δ _EC is compatible with each other. The transmittance is considered to be high.

  Specific structural formulas of the compounds according to the present invention are exemplified below. However, the compounds according to the present invention are not limited to these.

  Among the exemplified compounds, the compounds shown in Group A are those in which A and A ′ in the general formula [1] are the same alkyl group or aryl group. Since the structures represented by A and A ′ are present at the ortho position of the substituted phenyl group, they form a skeleton that protects the dithienothiophene structure with steric hindrance. Therefore, an electrochromic device using these compounds as an electrochromic material has high durability against repeated redox reactions.

  Among the exemplary compounds shown in Group B, one of A and A ′ in the general formula [1] is a hydrogen atom, and the other is an alkyl group or an aryl group. In this case, since the alkyl group or aryl group has a bulky structure or a long alkyl chain length, only one substituent of A and A ′ has an effect of protecting dithienothiophene.

  Among the compounds shown in Group A, a compound represented by the following general formula [2] is particularly preferable.

  In the general formula [2], A represents the same substituent and is a methyl group or a phenyl group. R represents the same substituent and is selected from a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

The phenyl group may have an alkyl group having 1 to 4 carbon atoms as a substituent.
n is 1 or 2.

  The compound according to the present invention can be synthesized, for example, using a reaction represented by the following formula [3]. In the formula, X is a halogen atom. A combination of a halogenated dithienothiophene and a boronic acid or boronic ester compound of a phenyl group having a substituent at the ortho position, or a phenyl group having a substituent at the ortho position with a boronic acid or boronic acid ester compound of dithienothiophene It can be synthesized by a coupling reaction using a Pd catalyst in combination with a halogen compound.

  Next, the electrochromic device according to this embodiment will be described.

  The electrochromic device according to this embodiment is a device having a pair of electrodes and an electrochromic layer and an electrolyte layer disposed between the pair of electrodes. This electrochromic layer has the organic compound according to the present invention.

  FIG. 1 is a cross-sectional view schematically showing an electrochromic device according to this embodiment. In FIG. 1, 1 is a first substrate, 2 is a first electrode, 3 is an electrochromic layer, 4 is an electrolyte layer, 5 is a second electrode, and 6 is a second substrate. In this way, the elements are stacked. The first substrate 1, the first electrode 2, the second electrode 5, and the second substrate 6 are all transparent. 3 and 4 are arranged between a pair of electrodes which are the electrode 2 and the electrode 5.

  The electrochromic device according to this embodiment can be obtained by depositing the organic compound according to the present invention on an electrode substrate. The film forming method is not particularly limited, but it can be dissolved in an appropriate solvent and known coating methods (for example, spin coating, dipping, casting method, LB method, ink jet method, etc.), vacuum deposition, ionization deposition, sputtering, plasma A thin film can be formed.

  The solvent used in the coating method using a solution is not particularly limited as long as it can dissolve an electrochromic compound and can be removed by volatilization after coating. Examples thereof include dimethyl sulfoxide, dimethylacetamide, dimethylformamide, and N-methylpyrrolidone. , Propylene glycol methyl ether acetate, dimethoxyethane, acetonitrile, propiononitrile, tetrahydrofuran, dioxane, methanol, ethanol, propanol, chloroform, toluene, xylene, methyl ethyl ketone, cyclohexanone and the like.

  The electrochromic layer according to this embodiment has polyvinyl carbazole.

  This electrochromic layer preferably has polycarbazole in the range of 50 wt% to 90 wt%. This is because polyvinyl carbazole increases the efficiency of transferring holes to the electrochromic compound.

  The molecular weight of polyvinyl carbazole is not particularly limited. Polyvinylcarbazole may be a polymer or a copolymer.

  The ion-conducting substance used for the ion-conducting layer is an ion-dissociating salt that exhibits good solubility in the solution or high compatibility with the solid electrolyte, and has an electron donating property to the extent that coloring of the electrochromic compound can be ensured. If it is a salt containing the anion which has, it will not specifically limit. For example, a liquid ion conductive substance, a gelled liquid ion conductive substance, or a solid ion conductive substance can be used.

  As said liquid type ion conductive substance, what dissolved support electrolytes, such as salts, acids, alkalis, etc. in the solvent can be used. The solvent is not particularly limited as long as it can dissolve the supporting electrolyte, but is preferably polar. Specifically, water, methanol, ethanol, propylene carbonate, ethylene carbonate, dimethyl sulfoxide, dimethoxyethane, acetonitrile, γ-butyrolactone, γ-valerolactone, sulfolane, dimethylformamide, dimethoxyethane, tetrahydrofuran, acetonitrile, propiononitrile, dimethyl Organic polar solvents such as acetamide, methylpyrrolidinone, dioxolane and the like can be mentioned.

The salt as the supporting electrolyte is not particularly limited, and examples thereof include inorganic ion salts such as various alkali metal salts and alkaline earth metal salts, quaternary ammonium salts, cyclic quaternary ammonium salts, and the like. Specifically, LiClO ₄ LiSCN, LiBF ₄ , LiAsF ₆ , LiCF ₃ SO ₃ , LiPF ₆ , LiI, NaI, NaSCN, NaClO ₄ , NaBF ₄ , NaAsF ₆ , alkali metals salts of Li, Na, K such as KSCN, KCl, etc. _{CH 3) 4 NBF 4, (} C 2 H 5) 4 NBF 4, (n-C 4 H 9) 4 NBF 4, (C 2 H 5) 4 NBr, (C 2 H 5) 4 NClO 4, (n -C ₄ H _{9) 4} NClO quaternary ammonium salts and cyclic quaternary ammonium salts such as _4.

  As the gelled liquid ion conductive substance, it is possible to use a highly viscous or gelled substance by adding a polymer or a gelling agent to the liquid ion conductive substance. it can. The polymer (gelator) is not particularly limited. For example, polyacrylonitrile, carboxymethylcellulose, polyvinyl chloride, polyethylene oxide, polypropylene oxide, polyurethane, polyacrylate, polymethacrylate, polyamide, polyacrylamide, polyester, and Nafion (registered) Trademark).

  The solid ion conductive material is not particularly limited as long as it is solid at room temperature and has ion conductivity, such as polyethylene oxide, oxyethylene methacrylate polymer, Nafion (registered trademark), polystyrene sulfonic acid, etc. Can be mentioned.

  These electrolyte materials may be used alone or in combination.

  Examples of the electrode material include indium tin oxide alloy (ITO), tin oxide (NESA), indium zinc oxide (IZO), silver oxide, vanadium oxide, molybdenum oxide, gold, silver, platinum, copper, indium, and chromium. Examples thereof include silicon materials such as metals, metal oxides, polycrystalline silicon, and amorphous silicon, and carbon materials such as carbon black, graphite, and glassy carbon. In addition, conductive polymers whose conductivity has been improved by doping treatment (for example, polyaniline, polypyrrole, polythiophene, polyacetylene, polyparaphenylene, polyethylenedioxythiophene (PEDOT) and polystyrenesulfonic acid complex, etc.) are also preferably used. .

  In the optical filter according to the present embodiment, transparency as an optical filter is also required. Therefore, ITO, IZO, NESA, and a conductive polymer with improved conductivity are not particularly preferable in the visible light region. Used. These can be used in various forms such as bulk and fine particles. These electrode materials may be used alone or in combination.

  The method for producing the electrochromic device according to this embodiment is not particularly limited, and an electrochromic layer is formed on the electrode substrate, and a vacuum injection method is provided in a gap provided between the substrate and the sealed counter electrode substrate. , A method of injecting by an atmospheric injection method, a meniscus method, etc., a method of forming a layer of an ion conductive material on an electrode substrate or an electrode substrate on which an electrochromic layer is formed, and then aligning the counter electrode substrate, A method of using an ion conductive substance or the like can be used.

  Since the electrochromic device according to the present embodiment is excellent in durability and high transparency at the time of decoloring, it can be suitably used for controlling the amount of incident light on an image sensor such as a camera. This is because the light passing through the electrochromic element is controlled. That is, the amount of light received by the light receiving element can be controlled by installing the electrochromic element in the imaging optical system (lens system). When the electrochromic element is in a decolored state, high transparency can be exhibited, so that a sufficient amount of transmitted light can be obtained with respect to incident light, and in the case of a colored state, optical characteristics for reliably blocking incident light can be obtained. .

Electrochromic property evaluation of exemplary compound A-1 The ITO substrate was ultrasonically cleaned with isopropyl alcohol and then vacuum-dried at 120 ° C. Next, a mixture of Exemplified Compound A-1 and polyvinylcarbazole (weight ratio 2: 8) was dissolved in a chlorolum solution to prepare a 2 wt% solution. And the solution of the mixture was apply | coated on the wash | cleaned ITO electrode substrate, and it dried after that, and produced the electrochromic layer. The layer was colorless and transparent, and the layer thickness was 5 ± 2 μm (± represents unevenness within 1 cm × 1 cm).

  Next, coloring and decoloring of the electrochromic layer on the ITO substrate were confirmed. The method of oxidation-reduction used an electrochemical reaction, the method of oxidizing and reducing an electrochromic compound, and the method of confirmation confirmed visually coloring and decoloring.

  Next, the ITO substrate having the electrochromic layer was immersed in a 0.1 M solution of lithium perchlorate in propylene carbonate. An electrochemical reaction was performed using this ITO substrate as a working electrode. The propylene carbonate solution is an electrolyte solution. This solution corresponds to the electrolyte layer of the electrochromic device. That is, carrier movement occurs between the electrochromic layer and this solution. The reference electrode was a silver / silver chloride electrode, and the counter electrode was a platinum electrode. Then, DC voltages of +1.5 and −1.5 V were applied to the working electrode to examine the presence or absence of coloring and decoloring.

  Polyvinylcarbazole did not dissolve in propylene carbonate.

  When a DC voltage of +1.5 V was applied to the working electrode for 50 seconds, the electrochromic layer on the working electrode was colored red, and the colored state was maintained in the entire region of the device. From this, it can confirm that the oxidation reaction of exemplary compound A-1 reacted in the whole area | region. Immediately after that, when a DC voltage of -1.5 V was applied for 50 seconds, the electrochromic layer became almost colorless. From this, since the transmittance became high in the entire in-plane region of the device, it was confirmed that the reduction reaction of the exemplary compound A-1 reacted in the entire in-plane region of the device.

  From the above results, an oxidation reaction and a reduction reaction in the solution were confirmed. From this, it is considered that the electrochromic device having polyvinyl carbazole and dithienothiophene undergoes a sufficient oxidation reaction, and thus a sufficient change in transmittance occurs.

  When phenanthroline is used instead of exemplary compound A-1, phenanthroline has a deeper level of HOMO energy than exemplary compound A-1, and therefore it is considered that fewer holes are supplied to phenanthroline than in the case of A-1. . For this reason, phenanthroline is not sufficiently oxidized and may leave a region of the element that is not colored.

  For comparison, a 2 wt% chloroform solution containing only exemplary compound A-1 without polyvinyl carbazole was prepared, cast on a cleaned ITO substrate, and dried. The layer was brittle and cloudy, and the layer thickness was 5 ± 1 μm.

  Next, the ITO substrate covered with exemplary compound A-1 was impregnated with a 0.1 M solution of lithium perchlorate in propylene carbonate to obtain a working electrode. A DC voltage of +1.5 and -1.5 V was applied to the working electrode to examine the presence or absence of coloring and decoloring, but neither coloring nor decoloring of the layer was confirmed. Dithienothiophene is presumed to have eluted in propylene carbonate.

  Since the electrochromic device according to this embodiment has polyvinyl carbazole, the electrochromic compound does not elute. In addition, since it is an electrochromic compound that can easily receive holes from polyvinyl carbazole, a sufficient change in transmittance can be obtained.

Table 3 shows examples and comparative examples. What is required of an electrochromic layer is film formability, transparency, and color fading. The film formability means that a film is formed on an ITO glass substrate with a uniform thickness and good adhesion, and that a film is formed.
Transparency refers to being colorless and transparent without white turbidity when no voltage is applied, and decoloring property refers to being decolored and transparent at -1V and colored at + 1V.

  In Examples 1 to 5, film formation was confirmed. In Examples 1 to 3, both the transparency and the color erasing property were good. This is because the film was formed by the presence of the polymer. In Examples 1 to 3, the difference in solubility parameter between the compound and the polymer is further small, and the compatibility between the two is high.

  In addition, the intermediate | middle in transparency in Table 3 means that a part of film | membrane was transparent and a part became cloudy.

  In Comparative Examples 1 and 2, not a film but a cloudy aggregate was formed on the ITO glass substrate. This is because it does not contain a polymer, and the compound is a low molecule and does not have film-forming properties.

From Table 3, the value of δ _P -δ _EC is preferably 0.17 or more and 0.68 or less.

  By using an electrochromic compound and a polymer organic compound that satisfy this range, an electrochromic device having film formability and transparency can be provided.

Claims (9)

An electrochromic device having a pair of electrodes and an electrochromic layer and an electrolyte layer disposed between the pair of electrodes,
The electrochromic layer has an electrochromic compound represented by the following general formula [1] and a polymer organic compound.

In the general formula [1], A and A ′ are each independently selected from a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, and an aryl group. However, at least one of A and A ′ is the alkyl group or the aryl group.
R ₁ and R ₂ are each independently selected from a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an aryl group, an aralkyl group, a substituted amino group, and a silyl group. .
The aryl group, the aralkyl group, the substituted amino group, and the silyl group represented by R ₁ and R ₂ may have an alkyl group having 1 to 4 carbon atoms as a substituent. n is 1 or 2.   2. The electrochromic device according to claim 1, wherein both A and A ′ of the compound represented by the general formula [1] are either a phenyl group or a methyl group.   2. The electrochromic device according to claim 1, wherein both A and A ′ of the compound represented by the general formula [1] are methyl groups.   The electrochromic device according to claim 1, wherein the high molecular organic compound is polyvinyl carbazole.   The electrochromic device according to any one of claims 1 to 3, wherein the high molecular organic compound is t-butyl polyacrylate.   The electrochromic device according to claim 1, wherein the high molecular organic compound is polystyrene.   The electrochromic device according to claim 1, wherein the high molecular organic compound is polymethyl methacrylate.   4. The polymer organic compound according to claim 1, wherein the polymer organic compound is a mixture of at least two polymer organic compounds selected from polyvinyl carbazole, poly (t-butyl acrylate), polystyrene, and poly (methyl methacrylate). The electrochromic element according to any one of the above. An imaging device having an imaging optical system and a light receiving element that receives light passing through the imaging optical system,
4. The imaging apparatus according to claim 1, wherein the light received by the light receiving element is light that has passed through the electrochromic element according to claim 1.