JP2016218359A - Method for driving electrochromic element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for driving an electrochromic element by which discoloration failure in a coloring state or degradation of the element can be suppressed.SOLUTION: A method for driving an electrochromic element (EC element) is provided, where the electrochromic element includes: an electrolyte layer 103 filling a space between a first electrode layer 101 and a second electrode layer 102 disposed to oppose to each other; a first electrochromic layer 104 comprising an oxidative electrochromic compound on a surface on the electrolyte layer 103 side of the first electrode layer 101; and a second electrochromic layer 105 comprising a reductive electrochromic compound on a surface on the electrolyte layer 103 side of the second electrode layer 102. The method includes a coloring driving step of driving the EC element into a coloring state and a discoloring driving step of driving the EL element into a discolored state. At least either of a voltage application time and a voltage magnitude necessary for discoloration in the discoloring driving step is controlled in accordance with a time required for coloring driving in the coloring driving step.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for driving an electrochromic device.

  A phenomenon in which a redox reaction occurs reversibly and a color changes reversibly by applying a voltage is called electrochromism. The electrochromic element utilizes the electrochromism. Many studies have been made to date on the electrochromic device as it can realize applications derived from the characteristics of the electrochromism.

  The electrochromic element can reversibly control the color development state and the color erasure state by voltage, but when the color development state is maintained for a long time, the color erasure by the color erasure driving becomes incomplete. There is a problem that unerasure occurs, and various proposals for solving the problem have been made.

  For example, when the power of the electrochromic display device is turned off without erasing driving, the coloring state continues for a long time, resulting in unerased color remaining. A technique for setting a program for performing the above has been proposed (see Patent Document 1).

  In addition, an electrochromic element having an electrochromic material on the working electrode is colored by applying a potential to the working electrode and then decoloring by applying a switching potential to the working electrode. However, the working electrode is completely colored. There is a technology that makes it possible to make it harder to disappear during subsequent switching operations by applying a reset potential of opposite polarity to the opposite electrode. It has been proposed (see Patent Document 2).

  The present invention provides an electrochromic element driving method capable of suppressing the disappearance of the coloring state by performing the optimum decoloring driving according to the time required for the coloring driving, and further suppressing the deterioration of the element. The purpose is to provide.

The method for driving the electrochromic device of the present invention as means for solving the above-described problems includes the first electrode layer,
A second electrode layer provided to face the first electrode layer;
An electrolyte layer filled between the first electrode layer and the second electrode layer;
A first electrochromic layer containing an oxidizable electrochromic compound on the surface of the first electrode layer on the electrolyte layer side;
A method for driving an electrochromic device having a second electrochromic layer containing a reducing electrochromic compound on a surface of the second electrode layer on the electrolyte layer side,
A color development driving step for performing color development for bringing the electrochromic element into a color development state;
A decoloring driving step for performing a decoloring drive for making the electrochromic element in a decoloring state,
In the coloring driving step, at least one of a time for applying a voltage for erasing in the erasing driving step and a voltage in the erasing driving step is adjusted according to the time for the coloring driving.

  According to the present invention, driving of an electrochromic element that can suppress the disappearance of the coloring state and further suppress the deterioration of the element by performing the optimum decoloring driving according to the time required for the coloring driving. A method can be provided.

FIG. 1 is a schematic cross-sectional view showing an example of an electrochromic element used in the method for driving an electrochromic element of the present invention. FIG. 2 shows an example of a driving voltage waveform applied in the electrochromic device driving method of the present invention. FIG. 3 shows an example of a driving voltage waveform applied in the electrochromic device driving method of the present invention. FIG. 4 shows an example of a drive voltage waveform applied in the electrochromic device driving method of the present invention. FIG. 5 is an example of a driving voltage waveform applied in the electrochromic device driving method of the present invention. FIG. 6 is an example of a driving voltage waveform applied in the electrochromic device driving method of the present invention.

(Driving method of electrochromic device)
The electrochromic element driving method of the present invention includes a color development driving process for performing color development for bringing the electrochromic element into a color development state, and a decolorization drive for performing decolorization driving for bringing the electrochromic element into a color elimination state. Including other steps as required.
In the present invention, in the coloring driving step, at least one of a time for applying a voltage for erasing in the erasing driving step and a voltage in the erasing driving step according to the time for the coloring driving. adjust.

<Electrochromic device>
The electrochromic element includes a first electrode layer, a second electrode layer provided so as to face the first electrode layer, and the first electrode layer and the second electrode layer. An electrolyte layer filled in between, and a first electrochromic layer containing an oxidizable electrochromic compound on the surface of the first electrode layer on the electrolyte layer side, and the electrolyte layer in the second electrode layer If it has the 2nd electrochromic layer containing a reducing electrochromic compound on the surface of the side, there will be no restriction | limiting in particular, According to the objective, it can select suitably, Furthermore, as needed, other members are used. Have.

<< first electrode layer, second electrode layer >>
The material for the first electrode layer and the second electrode layer is not particularly limited as long as it is a transparent material having conductivity, and can be appropriately selected according to the purpose. For example, indium oxide doped with tin (Hereinafter referred to as “ITO”), tin oxide doped with fluorine (hereinafter referred to as “FTO”), tin oxide doped with antimony (hereinafter referred to as “ATO”), zinc oxide, and other inorganic materials. Can be mentioned. Among these, InSnO, GaZnO, SnO, In ₂ O ₃ and ZnO are preferable.
In addition, carbon nanotubes with transparency and other highly conductive non-permeable materials such as Au, Ag, Pt, and Cu are formed in a fine network to improve conductivity while maintaining transparency. An electrode may be used.

The average thickness of each of the first electrode layer and the second electrode layer is adjusted so that an electrical resistance value necessary for the oxidation-reduction reaction of the electrochromic layer is obtained.
When the ITO is used as the material of the first electrode layer and the second electrode layer, the average thickness of each of the first electrode layer and the second electrode layer is, for example, 50 nm or more and 500 nm or less. preferable.

Examples of a method for manufacturing each of the first electrode layer and the second electrode layer include a vacuum deposition method, a sputtering method, and an ion plating method.
There is no particular limitation as long as each material of the first electrode layer and the second electrode layer can be formed by coating. For example, spin coating method, casting method, micro gravure coating method, gravure coating method, bar coating Method, roll coating method, wire bar coating method, dip coating method, slit coating method, capillary coating method, spray coating method, nozzle coating method, gravure printing method, screen printing method, flexographic printing method, offset printing method, reverse printing method Various printing methods such as an inkjet printing method can be used.

<< Electrolyte layer >>
The electrolyte layer is a solid electrolyte layer, and is formed as a film holding the electrolyte in light or thermosetting resin. Furthermore, it is preferable to mix inorganic particles for controlling the thickness of the electrolyte layer. Such an electrolyte layer is preferably a porous inorganic film previously coated on the electrochromic layer as a mixed solution of the inorganic fine particles, a curable resin, and an electrolyte, and then cured by light or heat. After the fine particle layer is formed, the film may be coated with a solution in which a curable resin and an electrolyte are mixed so as to penetrate into the inorganic fine particle layer, and then cured with light or heat. Furthermore, when the electrochromic layer is a layer in which an electrochromic compound is supported on conductive or semiconducting nanoparticles, the electrochromic layer is coated as a mixed solution of a curable resin and an electrolyte so as to penetrate into the electrochromic layer. Later, a film cured with light or heat may be used.

As the solution in which the electrolyte is mixed, a liquid electrolyte such as an ionic liquid or a solution in which a solid electrolyte is dissolved in a solvent is used.
Examples of the electrolyte material include inorganic ion salts such as alkali metal salts and alkaline earth metal salts, quaternary ammonium salts, acids, and supporting salts of alkalis. Specific examples include LiClO ₄ and LiBF _4. , LiAsF ₆ , LiPF ₆ , LiCF ₃ SO ₃ , LiCF ₃ COO, KCl, NaClO ₃ , NaCl, NaBF ₄ , NaSCN, KBF ₄ , Mg (ClO ₄ ) ₂ , Mg (BF ₄ ) _{2 and the} like.

There is no restriction | limiting in particular as said ionic liquid, According to the objective, it can select suitably, What kind of substance is generally used as long as it is researched or reported.
An organic ionic liquid has a molecular structure that exhibits a liquid in a wide temperature range including room temperature.
The molecular structure is composed of a cation component and an anion component.
Examples of the cation component include imidazole derivatives such as N, N-dimethylimidazole salt, N, N-methylethylimidazole salt, and N, N-methylpropylimidazole salt; N, N-dimethylpyridinium salt, N, N- Examples include aromatic salts such as pyridinium derivatives such as methylpropylpyridinium salts; aliphatic quaternary ammonium compounds such as tetraalkylammonium such as trimethylpropylammonium salt, trimethylhexylammonium salt, and triethylhexylammonium salt.
The anion component is preferably a compound containing fluorine in terms of stability in the atmosphere. For example, BF ₄ ⁻ , CF ₃ SO ₃ ⁻ , PF ₄ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ , B ( CN ₄₎ ^-, and the like. An ionic liquid formulated by a combination of these cationic components and anionic components can be used.

  Examples of the solvent include propylene carbonate, acetonitrile, γ-butyrolactone, ethylene carbonate, sulfolane, dioxolane, tetrahydrofuran, 2-methyltetrahydrofuran, dimethyl sulfoxide, 1,2-dimethoxyethane, 1,2-ethoxymethoxyethane, and polyethylene glycol. , Alcohols, or a mixed solvent thereof.

  Examples of the curable resin include common materials such as acrylic resins, urethane resins, epoxy resins, vinyl chloride resins, ethylene resins, melamine resins, phenolic resins and other photocurable resins, and thermosetting resins. However, a material having high compatibility with the electrolyte is preferable. The material is preferably an ethylene glycol derivative such as polyethylene glycol or polypropylene glycol. Further, as the curable resin, it is preferable to use a photocurable resin. This is because the device can be manufactured at a low temperature and in a short time compared to thermal polymerization or a method of thinning the film by evaporating the solvent.

  A particularly preferable combination constituting the electrolyte layer is composed of a solid solution of a matrix polymer containing an oxyethylene chain or an oxypropylene chain and an ionic liquid. By using the above configuration, it is easy to achieve both hardness and high ionic conductivity.

The inorganic fine particle is not particularly limited as long as it is a material capable of forming a porous layer and holding the electrolyte layer and the curable resin, but the stability and visibility of the electrochromic reaction are not limited. From the viewpoint, a material having high insulation, transparency, and durability is preferable. Specific examples of the material include oxides or sulfides such as silicon, aluminum, titanium, zinc, and tin, or mixtures thereof.
There is no restriction | limiting in particular in the magnitude | size (average particle diameter) of the said inorganic fine particle, Although it can select suitably according to the objective, 10 nm-10 micrometers are preferable, and 10 nm-100 nm are more preferable.

<< First Electrochromic Layer >>
The first electrochromic layer includes a material that is colored by an oxidation reaction.
As the material that is colored by the oxidation reaction, for example, at least one selected from a triarylamine compound, a Prussian blue complex, and nickel oxide is used.

Examples of the triarylamine compound include those described in Chem. Mater. 2006.18, 5823-5829, Org. Electron. Examples include compounds described in 2014.15, 428-434, Japanese Patent Application No. 2014-162598, and the like.
Examples of the Prussian blue complex include a material composed of Fe (III) ₄ [Fe (II) (CN) ₆ ] ₃ , and a solution in which fine particles of these pigments are dispersed can be used.
As the first electrochromic layer, a structure in which an organic electrochromic compound is supported on conductive or semiconductive fine particles is preferably used.

<< Second Electrochromic Layer >>
Each of the second electrochromic layers is a layer containing an electrochromic material that causes a color change due to a reduction reaction.
The electrochromic material may be either an inorganic electrochromic compound or an organic electrochromic compound. Alternatively, a conductive polymer known to exhibit electrochromism may be used.

Examples of the inorganic electrochromic compound include tungsten oxide, molybdenum oxide, iridium oxide, and titanium oxide.
Examples of the organic electrochromic compound include viologen, rare earth phthalocyanine, and styryl.
Examples of the conductive polymer include polypyrrole, polythiophene, polyaniline, or derivatives thereof.

As the second electrochromic layer, a structure in which an organic electrochromic compound is supported on conductive or semiconductive fine particles is preferably used. Specifically, it has a structure in which fine particles having a particle diameter of about 5 nm to 50 nm are bound to the electrode surface, and an organic electrochromic compound having a polar group such as phosphonic acid, carboxyl group, silanol group or the like is adsorbed on the surface of the fine particles. .
In the structure, since electrons are efficiently injected into the organic electrochromic compound by utilizing the large surface effect of the fine particles, a high-speed response is possible as compared with the conventional electrochromic display element. Furthermore, since a transparent film can be formed as a display layer by using fine particles, a high color density of the electrochromic dye can be obtained. A plurality of types of organic electrochromic compounds may be supported on conductive or semiconductive fine particles. Furthermore, electroconductive particle can serve as electroconductivity as an electrode layer.
Specifically, polymer-based and dye-based electrochromic compounds include, for example, azobenzene, anthraquinone, diarylethene, dihydroprene, dipyridine, styryl, styrylspiropyran, spirooxazine, spirothiopyran, thioindigo. , Tetrathiafulvalene, terephthalic acid, triphenylmethane, benzidine, triphenylamine, naphthopyran, viologen, pyrazoline, phenazine, phenylenediamine, phenoxazine, phenothiazine, phthalocyanine, Examples thereof include low molecular organic electrochromic compounds such as fluoran, fulgide, benzopyran, and metallocene, and conductive polymer compounds such as polyaniline and polythiophene. These may be used individually by 1 type and may use 2 or more types together.
Among these, viologen compounds and dipyridine compounds are preferable from the viewpoint of low color development / discoloration potential and good color values. For example, dipyridine compounds represented by the following general formula (1) are more preferable.

<General formula (1)>

In the general formula (1), R1 and R2 each independently represent an optionally substituted alkyl group having 1 to 8 carbon atoms and an aryl group, and at least one of R1 and R2 is , COOH, PO (OH) ₂ , and Si (OC _k H _{2k + 1} ) ₃ (wherein k represents 1 to 20).
In the general formula (1), X represents a monovalent anion. The monovalent anion is not particularly limited as long as it forms a stable pair with the cation moiety, and can be appropriately selected according to the purpose. For example, Br ion (Br ⁻ ), Cl ion (Cl ⁻ ), ClO ₄ ions (ClO ₄ ⁻ ), PF ₆ ions (PF ₆ ⁻ ), BF ₄ ions (BF ₄ ⁻ ), and the like.
In the said General formula (1), n, m, and 1 represent 0, 1, or 2 each independently.
In the said General formula (1), A, B, and C represent either the C1-C20 alkyl group, aryl group, and heterocyclic group which may have a substituent each independently.

  In addition, as the metal complex-based and metal oxide-based electrochromic compounds, for example, inorganic electrochromic compounds such as titanium oxide, vanadium oxide, tungsten oxide, indium oxide, iridium oxide, nickel oxide, and Prussian blue can be used. it can.

There is no restriction | limiting in particular as electroconductive or semiconductive fine particle which carries the said electrochromic compound, Although it can select suitably according to the objective, It is preferable to use a metal oxide.
Examples of the metal oxide material include titanium oxide, zinc oxide, tin oxide, zirconium oxide, cerium oxide, yttrium oxide, boron oxide, magnesium oxide, strontium titanate, potassium titanate, barium titanate, and calcium titanate. , Calcium oxide, ferrite, hafnium oxide, tungsten oxide, iron oxide, copper oxide, nickel oxide, cobalt oxide, barium oxide, strontium oxide, vanadium oxide, aluminosilicate, calcium phosphate, aluminosilicate, etc. Is mentioned. These may be used individually by 1 type and may use 2 or more types together.
Among these, from the viewpoint of physical properties such as electrical properties and optical properties such as electrical conductivity, from titanium oxide, zinc oxide, tin oxide, zirconium oxide, iron oxide, magnesium oxide, indium oxide, and tungsten oxide. At least one selected from the above is preferable, and titanium oxide is particularly preferable from the viewpoint that a color display excellent in response speed of color development and decoloration is possible.

  The shape of the conductive or semiconductive fine particles is not particularly limited and can be appropriately selected according to the purpose. In order to efficiently carry the electrochromic compound, the surface area per unit volume (hereinafter referred to as specific surface area). ) Is used. For example, when the fine particle is an aggregate of nanoparticles, it has a large specific surface area, so that the electrochromic compound is more efficiently supported and the display contrast ratio of color development and decoloration is excellent.

  The second electrochromic layer and the conductive or semiconductive fine particle layer may be formed by vacuum film formation, but is preferably formed by coating as a particle dispersion paste from the viewpoint of productivity.

  The average thickness of the first electrochromic layer and the second electrochromic layer is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 0.2 μm to 5.0 μm. When the average thickness is 0.2 μm or more, a color density can be obtained reliably, and when the average thickness is 5.0 μm or less, the manufacturing cost can be suppressed and the deterioration of visibility due to coloring can be prevented. it can.

<< Other parts >>
There is no restriction | limiting in particular as said other member, According to the objective, it can select suitably, For example, a support body (it may be mentioned a board | substrate), an insulating porous layer, a deterioration prevention layer, a protective layer etc. are mentioned. It is done.

<<< Support >>>
The support is not particularly limited as long as it is formed of a transparent material that can support each layer and can support each layer, and the shape, structure, size, material, and the like are not particularly limited. can do.

  There is no restriction | limiting in particular as a shape of the said support body, According to the objective, it can select suitably, For example, the shape which has flat plate shape, a curved surface, etc. are mentioned.

  There is no restriction | limiting in particular as a structure of the said support body, According to the objective, it can select suitably.

  There is no restriction | limiting in particular as a magnitude | size of the said support body, According to the objective, it can select suitably.

  As the material of the support, it is sufficient if it is transparent, and well-known organic materials and inorganic materials can be used as they are, for example, glass substrates such as alkali-free glass, borosilicate glass, float glass, and soda lime glass, In addition, resin substrates such as polycarbonate resin, acrylic resin, polyethylene, polyvinyl chloride, polyester, epoxy resin, melamine resin, phenol resin, polyurethane resin, and polyimide resin can be used.

  The surface of the support may be provided with a transparent insulating layer, a UV cut layer, an antireflection layer, or the like in order to improve water vapor barrier properties, gas barrier properties, ultraviolet resistance, and visibility.

<<< Insulating porous layer >>>
The insulating porous layer has a function of retaining an electrolyte while isolating the first electrode layer and the second electrode layer so as to be electrically insulated. The material of the insulating porous layer is not particularly limited as long as it is porous, and can be selected as appropriate. However, organic materials and inorganic materials having high insulating properties and durability and excellent film forming properties, and those It is preferable to use a complex of
As the method for forming the insulating porous layer, for example, a sintering method (using fine pores formed between particles by partially fusing polymer fine particles or inorganic particles by adding a binder or the like), extraction, etc. Method (after forming a constituent layer with a solvent-soluble organic or inorganic substance and a binder that does not dissolve in the solvent, the organic or inorganic substance is dissolved in the solvent to obtain pores), foaming foaming method, good solvent and poor Examples include a phase change method in which a solvent is manipulated to phase-separate a mixture of polymers, and a radiation irradiation method in which various radiations are emitted to form pores.

<<< Deterioration prevention layer >>>
The role of the deterioration preventing layer is to perform a chemical reaction reverse to that of the electrochromic layer, and to balance the charge, the first electrode layer and the second electrode layer are corroded or deteriorated by an irreversible redox reaction. Is to suppress it. In addition, the reverse reaction includes acting as a capacitor in addition to the case where the degradation preventing layer is oxidized and reduced.
The material of the deterioration preventing layer is not particularly limited as long as it is a material that plays a role of preventing corrosion due to irreversible oxidation-reduction reaction of the first electrode layer and the second electrode layer, and is appropriately selected depending on the purpose. For example, antimony tin oxide, nickel oxide, titanium oxide, zinc oxide, tin oxide, or a conductive or semiconductive metal oxide containing a plurality of them can be used.
The deterioration preventing layer can be composed of a porous thin film that does not hinder electrolyte injection. For example, conductive or semiconductive metal oxides such as antimony tin oxide, nickel oxide, titanium oxide, zinc oxide, and tin oxide can be used. By immobilizing fine particles on the second electrode with, for example, an acrylic, alkyd, isocyanate, urethane, epoxy, phenolic binder, the electrolyte permeability and the function as a deterioration preventing layer A suitable porous thin film satisfying the above can be obtained.

<<< Protective layer >>>
The role of the protective layer is unnecessary for protecting the device from external stress and chemicals in the cleaning process, preventing leakage of electrolyte, and stable operation of the electrochromic device such as moisture and oxygen in the atmosphere. For example, to prevent the entry of things.
There is no restriction | limiting in particular as average thickness of the said protective layer, Although it can select suitably according to the objective, 1 micrometer-200 micrometers are preferable.
As the material for the protective layer, for example, an ultraviolet curable resin or a thermosetting resin can be used, and specific examples include acrylic, urethane, and epoxy resins.

<Color development driving process>
If the electrochromic device is in the process of performing color driving in which a voltage applied for color development is applied between the first electrode and the second electrode in order to bring the electrochromic element into a color developing state, the magnitude of the voltage The voltage application time, the voltage application method, and the like are not particularly limited and can be appropriately selected according to the purpose. In addition, it is preferable that the voltage applied to the color development is a voltage equal to or higher than a threshold necessary for causing both the oxidizing electrochromic compound and the reducing electrochromic compound to cause a color change.
The magnitude of the voltage is not particularly limited as long as the electrochromic element can be in a colored state, and can be appropriately selected according to the purpose.
There is no restriction | limiting in particular as said application time, According to the objective, it can select suitably.
The method for applying the voltage is not particularly limited and can be appropriately selected according to the purpose. For example, when the voltage applied for color development is V1, the color development driving process is started at the same time as the voltage development process is started. A method of applying a constant voltage V1 after sweeping to the voltage V1 for color development at a voltage sweep rate, a constant voltage V3 after sweeping to a voltage V3 greater than the voltage V1 for color development at a predetermined voltage sweep rate The method of applying the voltage V1 at a constant value after applying the voltage, the operation of applying the voltage V1 for the color development at a constant value after sweeping to the voltage V1 for the color development, and the operation of making an open circuit are repeated. And a method of opening the circuit after sweeping to the voltage V1 required for the color development.
Here, the voltage V3 larger than the voltage V1 means a voltage having the same polarity as the voltage V1 and having a potential difference larger than the potential difference between 0V and the voltage V1.

<Decolorization driving process>
In order to put the electrochromic element in a decoloring state, a decoloring time adjusted according to a time corresponding to the time required for the color development driving between the first electrode and the second electrode. As long as the process of performing decoloring driving for applying the voltage for decoloring is used, the magnitude of the voltage, the method for applying the voltage, and the like are not particularly limited, and can be appropriately selected according to the purpose. In addition, it is preferable that the voltage applied to the decoloring is a voltage that is equal to or higher than a threshold necessary for both the oxidizing electrochromic compound and the reducing electrochromic compound to return to the original color.
The magnitude of the voltage is not particularly limited as long as the electrochromic element can be in a decolored state, and can be appropriately selected according to the purpose, but is adjusted according to the time required for the color development driving. It is preferable to apply a voltage of a certain magnitude.
The method for applying the voltage is not particularly limited and can be appropriately selected according to the purpose. For example, when the voltage applied to the color erasure is V2, the erasing driving is started simultaneously with the voltage erasing driving. A method in which the voltage V2 is applied only for a time adjusted according to the time required for the color development driving, and the voltage after sweeping up to the voltage V2 required for the color erasing at a predetermined voltage sweep speed at the same time as the previous color erasing driving is started. Examples include a method in which V2 is applied at a constant value during the decoloring time adjusted according to the time required for the color development driving.

  In addition, the electrochromic element uses the potentiostat to apply the driving voltage waveform between both the first electrode and the second electrode, thereby performing the coloring driving and the decoloring driving. Do. Regarding the adjustment of the color erasing drive, a table regarding the voltage for the color erasing and the time for the color erasing optimized in advance according to the time required for the color development driving is provided in the driving circuit and the control circuit. Preferably, by feeding back the information on the color development time, it is possible to adjust to the optimum color erasing drive and suppress unerasing residue when the color development state is maintained for a long time. Further, depending on how the voltage is applied, the deterioration of the electrochromic element can be suppressed by preventing an inrush current.

<Other processes>
There is no restriction | limiting in particular as said other process, According to the objective, it can select suitably.

The driving method of the electrochromic device of the present invention has the following effects. That is,
By adjusting at least one of the erasing voltage and the erasing time in accordance with the time required for the color development driving, it is possible to reduce the erasing residual.
By continuing to apply a constant voltage, the controllability of the color density can be kept high.
By sweeping to the set voltage, inrush current can be suppressed, and deterioration of the electrochromic element can also be suppressed.
By applying a voltage V3 larger than the voltage V1 in the initial stage, it is possible to improve the speed (coloring response speed) for changing from the transparent state to the coloring state.
By repeating the application of the voltage for color development and the open circuit, it is possible to prevent a decrease in color density and maintain a constant density.
After changing from the transparent state to the colored state, an open circuit can be used, so that the electric power required to maintain the colored state can be omitted.

  Hereinafter, although an example of the present invention is described with reference to drawings, the present invention is not limited to this example. Note that the reference numerals such as “1” in the drawings mean the same thing.

Example 1
FIG. 1 is a schematic cross-sectional view showing an example of an electrochromic element used in the method for driving an electrochromic element of the present invention.
A method for manufacturing the electrochromic element shown in FIG. 1 will be described in detail.
An ITO film of about 100 mm was formed on a 40 mm × 40 mm glass substrate 107 by a sputtering method in a 30 mm × 30 mm region and a lead portion, and the first electrode 101 was produced. The resistance in the surface of the first electrode 101 was about 20Ω. On top of this, poly (ethylene glycol) diacrylate, photoinitiator 1-hydroxy-cyclohexyl-phenyl-ketone (IRGACURE 184, manufactured by BASF), a compound represented by the following structural formula B and 2-butanone are massed. A solution mixed at a ratio (20: 1: 20: 400) was applied and UV-cured in a nitrogen atmosphere to form an oxidizable electrochromic layer 104.

[Structural formula B]

  Next, an ITO film having a thickness of about 100 nm was formed on another 40 mm × 40 mm glass substrate 107 by a sputtering method in a 30 mm × 30 mm region and a lead portion, and the second electrode 102 was manufactured. The resistance in the plane of the second electrode 102 was about 20Ω. On top of this, 4,4 ′-(1-phenyl-1H-pyrrole-2,5-diyl) bis (1- (4- (phosphomethylethyl) benzyl) pyridinium) bromide is a reducing electrochromic compound that develops reddish purple color. Containing 5 mass% of 2.2.2.3. A reducing electrochromic layer 105 was formed by spin-coating a tetrafluoropropanol solution and annealing at 120 ° C. for 10 minutes.

  Next, 1-ethyl-3-methylimidazolium bis (trifluoromethanesulfonyl) imide, which is an ionic liquid, was used as the electrolyte. A bead spacer having a particle diameter of 10 μm is placed in the electrolyte in an amount of 0.2% by mass, and an appropriate amount is dropped on the glass substrate 107 on which the first electrode 101 and the oxidizable electrochromic layer 104 are formed. And the glass substrate 107 in which the reducing electrochromic layer 105 was formed was bonded together, and the electrochromic element was produced.

  The electrochromic element having the structure shown in FIG. 1 was connected to a potentiostat (ModuLab, manufactured by Toyo Technica Co., Ltd.), and the drive voltage waveform shown in FIG. 2 was applied. The transmittance was measured with USB4000 (manufactured by Ocean Optics), and the average value (%) of the transmittance at wavelengths of 400 nm to 800 nm was calculated. The difference between the transmittance (%) in the initial state and the transmittance (%) after the decoloring drive was defined as “unerased” (%). When the time T1 required for the color development drive is changed, the voltage V2 [V] and the time (T2-T1) [s] required for the color erase drive are adjusted so as to suppress the remaining disappearance, and the remaining disappearance is evaluated as follows. Evaluation was made according to the criteria.

〔Evaluation criteria〕
A: Less than 1% disappearance remaining: 1% or more but less than 5% ×: Remaining disappearance 5% or more

  The evaluation results are shown in Table 1. From Table 1, it can be seen that the remaining unerased can be suppressed by adjusting the voltage V2 [V] and the time (T2−T1) [s] required for the decoloring drive according to the time T1 required for the color driving. I can confirm.

(Example 2)
The production method and evaluation method of the electrochromic element were the same as in Example 1, and the drive voltage waveform shown in FIG. 3 was applied to the electrochromic element, and the remaining disappearance was evaluated. The voltage sweep speed in FIG. 3 was 10 [V / s]. The evaluation results are shown in Table 2. From Table 2, it can be seen that the remaining disappearance can be suppressed by adjusting the voltage V2 [V] and the time (T2−T1) [s] required for the decoloring drive according to the time T1 required for the color driving. I can confirm.

Example 3
The production method and evaluation method of the electrochromic element were the same as in Example 1, and the drive voltage waveform shown in FIG. 4 was applied to the electrochromic element to evaluate the disappearance. The voltage sweep speed in FIG. 4 was 10 [V / s]. The evaluation results are shown in Table 3. From Table 3, it can be seen that the remaining disappearance can be suppressed by adjusting the voltage V2 [V] and the time (T2−T1) [s] required for the decoloring drive according to the time T1 required for the color driving. I can confirm.

Example 4
The production method and evaluation method of the electrochromic device were the same as those in Example 1, and the drive voltage waveform shown in FIG. 5 was applied to the electrochromic device to evaluate the disappearance. The voltage sweep speed in FIG. 5 was 10 [V / s]. The evaluation results are shown in Table 4. From Table 4, it can be understood that the remaining disappearance can be suppressed by adjusting the voltage V2 [V] and the time (T2−T1) [s] required for the decoloring drive according to the time T1 required for the color driving. I can confirm.

(Example 5)
The production method and evaluation method of the electrochromic element were the same as in Example 1, and the drive voltage waveform shown in FIG. 6 was applied to the electrochromic element, and the disappearance was evaluated. The voltage sweep speed in FIG. 6 was 10 [V / s]. The evaluation results are shown in Table 5. From Table 5, it can be seen that the remaining disappearance can be suppressed by adjusting the voltage V2 [V] and the time (T2−T1) [s] required for the decoloring drive according to the time T1 required for the color driving. I can confirm.

(Comparative Example 1)
In Example 1, when the time T1 required for color development driving is changed, the voltage V2 [V] and time (T2−T1) [s] required for decoloring driving are set to 0 [V] and 10 [s], respectively. The remaining disappearance was evaluated under fixed conditions. The evaluation results are shown in Table 6. From Table 6, it can be confirmed that the disappearance is increased as the time T1 required for color development is increased.

(Comparative Example 2)
In the second embodiment, when the time T1 required for the color development drive is changed, the voltage V2 [V] and the time (T2-T1) [s] required for the decoloring drive are set to 0 [V] and 10 [s], respectively. The remaining disappearance was evaluated under fixed conditions. Table 7 shows the evaluation results. From Table 7, it can be confirmed that the remaining amount increases as the time T1 required for color development increases.

(Comparative Example 3)
In Example 3, when the time T1 required for color development driving is changed, the voltage V2 [V] and time (T2-T1) [s] required for decoloring driving are set to 0 [V] and 10 [s], respectively. The remaining disappearance was evaluated under fixed conditions. The evaluation results are shown in Table 8. From Table 8, it can be confirmed that the disappearance remaining increases as the time T1 required for color development increases.

(Comparative Example 4)
In Example 4, when the time T1 required for color development driving is changed, the voltage V2 [V] and time (T2-T1) [s] required for decoloring driving are set to 0 [V] and 10 [s], respectively. The remaining disappearance was evaluated under fixed conditions. Table 9 shows the evaluation results. From Table 9, it can be confirmed that the remaining amount increases as the time T1 increases.

(Comparative Example 5)
In Example 5, when the time T1 required for color development driving is changed, the voltage V2 [V] and time (T2−T1) [s] required for decoloring driving are set to 0 [V] and 8 [s], respectively. The remaining disappearance was evaluated under fixed conditions. Table 10 shows the evaluation results. From Table 10, it can be confirmed that the remaining amount increases as the time T1 increases.

As an aspect of this invention, it is as follows, for example.
<1> a first electrode layer;
A second electrode layer provided to face the first electrode layer;
An electrolyte layer filled between the first electrode layer and the second electrode layer;
A first electrochromic layer containing an oxidizable electrochromic compound on the surface of the first electrode layer on the electrolyte layer side;
A method for driving an electrochromic device having a second electrochromic layer containing a reducing electrochromic compound on a surface of the second electrode layer on the electrolyte layer side,
A color development driving step for performing color development for bringing the electrochromic element into a color development state;
A decoloring driving step for performing a decoloring drive for making the electrochromic element in a decoloring state,
In the color development driving step, according to the time required for the color development driving, at least one of a time for applying a voltage for color erasing in the color erasing driving step and a voltage in the color erasing driving step is adjusted. The driving method of the electrochromic element.
<2> The electrochromic device according to <1>, wherein when the time required for the color development driving in the color development driving step is lengthened, the time for applying the voltage for the color erasing in the color erasing driving step is adjusted to be long. This is a driving method.
<3> When the color development is performed, a voltage V1 that is equal to or higher than a threshold necessary for causing both the oxidizing electrochromic compound and the reducing electrochromic compound to cause a color change is applied to the first electrode layer and the second electrode. The method for driving an electrochromic element according to any one of <1> to <2>, wherein the driving is applied between the electrode layer and the electrode layer.
<4> The decoloring driving is performed by applying a voltage V2 that is equal to or higher than a threshold value required for both the oxidizing electrochromic compound that has changed color and the reducing electrochromic compound that has changed color to return to the original color. The method for driving an electrochromic device according to any one of <1> to <3>, wherein the driving is applied between one electrode layer and the second electrode layer.
<5> The coloring driving causes the voltage between the first electrode layer and the second electrode layer to cause a color change between the oxidizing electrochromic compound and the reducing electrochromic compound. The method for driving an electrochromic element according to any one of <1> to <4>, wherein the voltage V1 is swept up to a voltage V1 that is greater than or equal to a threshold necessary for the voltage V1, and then the voltage V1 is applied at a constant value. .
<6> The erasing drive sweeps the voltage V2 that is equal to or higher than a threshold necessary for the color-changed oxidizing electrochromic compound and the color-changed reducing electrochromic compound to return to the original color. The method of driving an electrochromic device according to any one of <1> to <5>, wherein the voltage V2 is applied at a constant value after being applied.
<7> The color development causes the voltage between the first electrode layer and the second electrode layer to cause a color change between the oxidizing electrochromic compound and the reducing electrochromic compound. <1> to <6>, in which the voltage V3 is swept up to a voltage V3 lower than the voltage V1 that is more than the threshold necessary to apply the voltage V3 at a constant value and then the voltage V1 is applied at a constant value. A method for driving an electrochromic device according to any one of the above.
<8> The coloring driving causes the voltage between the first electrode layer and the second electrode layer to cause a color change between the oxidizing electrochromic compound and the reducing electrochromic compound. In any one of <1> to <6>, the driving is performed by repeating the operation of applying the voltage V1 at a constant value and the operation of opening the circuit after sweeping to the voltage V1 that is equal to or higher than a threshold necessary for the operation. It is a drive method of the described electrochromic element.
<9> The color development causes the voltage between the first electrode layer and the second electrode layer to cause a color change between the oxidizing electrochromic compound and the reducing electrochromic compound. The method of driving an electrochromic device according to any one of <1> to <6>, wherein the circuit is driven to open circuit after being swept up to the voltage V1 that is greater than or equal to a threshold necessary for the purpose.
<10> The method for driving an electrochromic device according to any one of <5> to <9>, wherein a voltage sweep speed when sweeping the voltage is 10 [V / s].

  The method for driving an electrochromic device according to any one of <1> to <10> solves the above-described problems and achieves the following object. That is, the driving method of the electrochromic element can suppress the disappearance when the coloring state is kept for a long time by performing the optimum decoloring driving according to the coloring time, and further suppress the deterioration of the element. It is an object of the present invention to provide a method for driving an electrochromic device that can be used.

Japanese Patent Laid-Open No. 11-316396 JP 2013-114079 A

DESCRIPTION OF SYMBOLS 101 1st electrode layer 102 2nd electrode layer 103 Electrolyte layer 104 Oxidative electrochromic layer 105 Reducible electrochromic layer 107 Substrate

Claims (9)

A first electrode layer;
A second electrode layer provided to face the first electrode layer;
An electrolyte layer filled between the first electrode layer and the second electrode layer;
A first electrochromic layer containing an oxidizable electrochromic compound on the surface of the first electrode layer on the electrolyte layer side;
A method for driving an electrochromic device having a second electrochromic layer containing a reducing electrochromic compound on a surface of the second electrode layer on the electrolyte layer side,
A color development driving step for performing color development for bringing the electrochromic element into a color development state;
A decoloring driving step for performing a decoloring drive for making the electrochromic element in a decoloring state,
In the color development driving step, according to the time required for the color development driving, at least one of a time for applying a voltage for color erasing in the color erasing driving step and a voltage in the color erasing driving step is adjusted. A method for driving an electrochromic device.   2. The method of driving an electrochromic device according to claim 1, wherein when the time required for the color development drive in the color development drive step is lengthened, the time for applying the voltage for the color erase in the color erase drive step is adjusted to be long.   In the color development, the first electrode layer and the second electrode layer have a voltage V1 that is equal to or higher than a threshold value required for both the oxidizing electrochromic compound and the reducing electrochromic compound to cause a color change. The method for driving an electrochromic device according to claim 1, wherein the driving is applied between the two.   In the decoloring drive, the first electrode is supplied with a voltage V2 that is equal to or higher than a threshold necessary for both the oxidizing electrochromic compound that has changed color and the reducing electrochromic compound that has changed color to return to the original color. 4. The method for driving an electrochromic device according to claim 1, wherein the driving is applied between a layer and the second electrode layer.   The color development is necessary for the voltage between the first electrode layer and the second electrode layer to cause a color change between the oxidizing electrochromic compound and the reducing electrochromic compound. 5. The method of driving an electrochromic device according to claim 1, wherein the voltage V <b> 1 is applied at a constant value after the voltage V <b> 1 is swept to a threshold value or more.   After the erasing drive sweeps the oxidizable electrochromic compound whose color has changed and the reducing electrochromic compound whose color has changed to the voltage V2 which is equal to or higher than a threshold necessary for returning to the original color. 6. The method of driving an electrochromic device according to claim 1, wherein the driving is performed by applying the voltage V2 at a constant value.   The color development is necessary for the voltage between the first electrode layer and the second electrode layer to cause a color change between the oxidizing electrochromic compound and the reducing electrochromic compound. The electro according to any one of claims 1 to 6, wherein the driving is such that the voltage V3 is swept to a voltage V3 lower than the voltage V1 equal to or higher than a threshold, the voltage V3 is applied at a constant value, and then the voltage V1 is applied at a constant value. Driving method of chromic element.   The color development is necessary for the voltage between the first electrode layer and the second electrode layer to cause a color change between the oxidizing electrochromic compound and the reducing electrochromic compound. The electrochromic device according to any one of claims 1 to 6, wherein the driving is performed by repeating the operation of applying the voltage V1 at a constant value and the operation of opening the circuit after sweeping the voltage V1 above a certain threshold. Driving method.   The color development is necessary for the voltage between the first electrode layer and the second electrode layer to cause a color change between the oxidizing electrochromic compound and the reducing electrochromic compound. The method of driving an electrochromic device according to claim 1, wherein the driving is performed to make an open circuit after sweeping to the voltage V <b> 1 greater than or equal to a threshold value.