JP2006058617A - Electrochromic display element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrochromic display element adaptable to high speed rewriting and having satisfactory responsiveness. <P>SOLUTION: The electrochromic display element wherein a coloring layer consisting of a conductive polymer and an electrolyte layer containing a liquid electrolyte are provided between a transparent electrode and a counter electrode is characterized in that the liquid electrolyte is a liquid ionic liquid at 20°C and the coloring layer is formed by applying a liquid containing the conductive polymer onto the transparent electrode and/or the counter electrode and drying the resultant liquid. Thus, high speed rewriting is made possible. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrochromic display element having a mechanism that changes color by electrochemical oxidation or reduction.

  The electrochromic display element basically has a pair of electrodes, at least one of which is transparent, a chromic layer (hereinafter referred to as a coloring layer) sandwiched between the electrodes, and an electrolyte layer. When a voltage is applied between the electrodes, an oxidation-reduction reaction occurs in the vicinity of both the positive and negative electrodes, current flows, and the color developing layer undergoes a color change (hereinafter, this property is referred to as electrochromic property). An image is displayed using this principle.

  As materials for the color developing layer, pigments such as viologen, Prussian blue, and methylene blue, and inorganic materials such as tungsten oxide and nickel oxide have been studied.

  In recent years, research on a material called a conductive polymer has progressed as a material for the color developing layer. Although some of these materials exhibit electrochromic properties are known, a conventional method of forming a conductive polymer film is generally a method of electrolytic polymerization of a monomer to form a polymer film. ing.

As the electrolyte layer, a solution in which an electrolyte is dissolved or an ionic liquid is usually used. The electrolyte solution is generally (C ₄ H ₉ ) ₄ N ⁺ BF ₄ ⁻ / acetonitrile solution, LiClO ₄ / propylene carbonate solution, etc. In recent years, ionic liquids have been studied as electrolyte materials with the aim of improving efficiency. Yes. The ionic liquid is also called a room temperature molten salt, and an imidazole-based or ammonium-based material is used. Patent Document 1 discloses an electrochromic display element having an electrolyte layer holding a room temperature molten salt in a polymer matrix. Patent Document 2 discloses an electrochemical device having a structure in which an ionic liquid is sandwiched between electrodes provided with a conductive polymer.
JP 2003-15163 A Japanese Patent Laid-Open No. 2003-243028

  However, conventional electrochromic display elements have a problem that they are not responsive and cannot be rewritten at high speed. In Patent Document 1, an electrochromic element in which an ion conductive layer is sandwiched between two transparent conductive substrates, the electrochromic layer is provided on at least one of the conductive substrates, and the ion conductive layer is a polychromic element. The vinylidene fluoride polymer matrix contains at least one ion conductive substance selected from (a) a supporting electrolyte and a solvent, (b) a room temperature molten salt, and (c) a room temperature molten salt and a solvent. The electrochromic element is characterized by being an ion conductive sheet, and a spacer member such as a bead is not necessarily required in the electrolyte layer, and the electrolyte layer is in the form of a sheet and is easily manufactured. A possible method is disclosed. However, in the element described in Patent Document 1, since a polymer matrix is used, there is a problem that the resistance of ion movement is not exhibited and a sufficient response speed is not exhibited. Is damaged by the sheet member. In addition, the technique disclosed in Patent Document 2 is intended to reduce the environmental load, eliminate the risk of pressure increase and combustion, and improve the safety in unsteady or high temperature environments. Therefore, it does not suggest the idea of imparting responsiveness capable of high-speed rewriting to an electrochromic display element in which an electrolyte layer is formed using an ionic liquid. An object of the present invention is to provide an electrochromic display element that has good responsiveness and excellent color change.

  As a result of intensive studies, the present inventor has been able to solve the above problems with the configuration of any one of the following descriptions.

  The electrochromic display element according to claim 1, wherein the electrochromic display element is provided with a coloring layer made of a conductive polymer and an electrolyte layer containing a liquid electrolyte between a transparent electrode and a counter electrode. The electrolyte is an ionic liquid that is liquid at 20 ° C., and the coloring layer is formed by applying a liquid containing a conductive polymer to the transparent electrode and / or the counter electrode and drying. It is characterized by this.

  The electrochromic display element according to claim 2 is the electrochromic display element according to claim 1, characterized in that the coating is spin coating or bar coating.

The electrochromic display element according to claim 3 is the electrochromic display element according to claim 1 or 2, wherein the ionic liquid is a compound having BF ₄ ⁻ .

  The electrochromic display element according to claim 4 is the electrochromic display element according to claim 1 or 2, wherein the ionic liquid is a compound having an anion having the following structure.

(CF ₃ (CF ₂ ) _n SO ₂ ) ₂ N ⁻ (where n represents 0 or 1)
The electrochromic display element according to claim 5 is the electrochromic display element according to any one of claims 1 to 4, wherein the ionic liquid is a compound having an ammonium cation. is there.

  The electrochromic display element according to claim 6 is the electrochromic display element according to any one of claims 1 to 4, wherein the ionic liquid is a compound having an imidazolium cation. It is.

  According to the present invention, it is possible to improve the responsiveness, which has been a problem in electrochromic display elements, by forming a coloring layer made of a conductive polymer film by a coating method and using an ionic liquid as an electrolyte. it can.

  In addition, since the coating method can form a film by a simpler method than the electrolytic polymerization method, it is effective in reducing the cost.

In particular, in the present invention, an ionic liquid such as BF ₄ ⁻ or (CF ₃ (CF ₂ ) _n SO ₂ ) ₂ N ⁻ (where n represents 0 or 1), an ammonium cation, It has been confirmed that the response is further improved by using a compound having an imidazolium cation. As described above, the present invention makes it possible to provide an electrochromic display element that can be manufactured at a low manufacturing cost while increasing the response speed, which has been a problem in the past.

  Hereinafter, an electrochromic display element according to the present invention will be described with reference to the accompanying drawings.

  FIG. 1 schematically shows a basic configuration of an electrochromic display element which is a typical embodiment of the present invention. The electrochromic display element 1 includes a transparent substrate 2 having a transparent electrode 3 and a substrate 4 having a counter electrode 5, and coloring layers 6 and 7 and an ionic liquid between the transparent electrode 3 and the counter electrode 5. The electrolyte layer 8 is sandwiched and the periphery thereof is sealed with a sealing material 9 made of resin. In addition, spacers 10 are arranged on the electrolyte layer 8 (only one is schematically shown in FIG. 1 but a large number are actually arranged). Voltage-applying lead wires 11 and 12 are connected to the transparent electrode 3 and the counter electrode 5, respectively.

This electrochromic display element 1 can be driven by a power source 20 by direct current drive, alternating current drive, and pulse waveform. A voltage is applied from the lead wires 11 and 12 to the transparent electrode 3 and the counter electrode 5, and an electric field is applied to the coloring layer and the electrolyte. Act on the layer. The decoloring is performed by applying an electric field having a polarity opposite to that at the time of color development.
Hereinafter, the configuration of the electrochromic display element of the embodiment will be specifically described.

(substrate)
As the transparent substrate 2, a transparent plastic substrate such as polycarbonate (PC), polyethersulfone (PES), polyarylate (PAR), polyethylene terephthalate (PET), etc. can be used in addition to transparent glass. As the substrate 4, any insulating material can be used regardless of whether it is transparent or colored, or a metal material coated with an insulating material may be used.

(electrode)
As the transparent electrode 3, for example, a transparent conductive film such as Indium Tin Oxide (ITO: Indium Tin Oxide) or Indium Zinc Oxide (IZO: Indium Zinc Oxide) can be used. The counter electrode 5 is made of an electrochemically stable metal or the like, for example, platinum, chromium, aluminum, cobalt, palladium, or the like. The counter electrode 5 may be formed of the same transparent conductive material as that of the transparent electrode 3. Such a material can be formed on the transparent substrate 2 or the substrate 4 by mask deposition by sputtering or entire surface deposition or coating, followed by patterning by photolithography or screen printing. The thickness of the electrode is not particularly limited, but is usually 10 nm to 2 μm, preferably 20 nm to 1 μm.

(Coloring layer)
Various coloring materials are known as materials for the coloring layers 6 and 7 exhibiting electrochromic characteristics, and among them, the conductive polymer film can produce a relatively tough film and is durable. Because it is rich, it is the most preferred material. Examples of the conductive polymer film include a material called a so-called conductive polymer material obtained by polymerizing monomers such as aniline, pyrrole, and thiophene. Specific examples include polyaniline, poly (3-hexylthiophene-2,5-diyl), and polypyrrole. Conventionally, a method of forming a conductive polymer film on an electrode by an electrolytic polymerization method is known, but this method is considered to be a dense state of the film surface, which is speculated that Since the oxidation-reduction reaction occurs only at the part, there is a problem that a sufficient color change cannot be obtained and the response speed is slow. As a result of considering the manufacturing method of the conductive polymer film in consideration of such points, the conductive polymer is dispersed or dissolved in a solvent, applied to a predetermined film thickness, and dried to sufficiently change the color. I found out that it can be done at high speed. The details of this mechanism are unknown, but by forming the conductive polymer film through a coating and drying process, it is possible to obtain a more porous film quality than the electrolytic polymerization method, which increases the surface area of the conductive polymer film. Furthermore, by combining the use of an ionic liquid as the electrolyte, it is considered that the color change rate due to the electrochemical reaction is increased and high-speed response is realized.

  As a solvent for dispersion or dissolution, water, acetone, toluene, tetrahydrofuran, chloroform or the like can be used. Moreover, sodium hydroxide, sodium carbonate, sulfuric acid, hydrochloric acid, etc. can be added as a pH adjuster for dispersion stability. These solvents are prepared so that the conductive polymer material is contained in an amount of 1% by mass to 20% by mass. This mixed solution is made into a uniform solution by a disperser or a stirrer. As the disperser, a colloid mill, a ball mill, or a sand mill is used. As the stirrer, a batch mixer or an in-line mixer can be used. As a method of applying the coating solution prepared in this way, there are a spin coat method and a bar coat method.

  In the spin coating method, a substrate is fixed by vacuum suction using an apparatus called a spinner, a coating liquid is dropped thereon, and then a predetermined film thickness is obtained by rotating at a high speed for a predetermined time. The rotation speed of the spinner can be applied at 100 to 5,000 rpm although it depends on the concentration of the coating solution. Further, the rotation speed is rotated at 100 to 500 rpm for the first 5 to 60 seconds, then increased to 1,000 to 5,000 in 5 to 30 seconds, and further rotated at the rotation speed for 5 to 60 seconds. A more uniform film can be produced by performing rotation at a two-stage speed switching from low speed to high speed.

  In the bar coat method, the coating solution dropped on the substrate was slid in a bar shape with a certain gap between the substrate or a wire wrapped with a wire with a thickness on a round bar was contacted. By sliding in a state, a coating film having a certain film thickness is obtained on the substrate. In the present embodiment, a so-called doctor blade is used as the application bar. The coating gap depends on the concentration of the coating solution, but about 1 to 100 μm is used.

  The coloring material applied by such an apparatus is put into a drying apparatus and dried. The drying device is not particularly limited, and a general hot air drying device or a vacuum drying device can be used. At this time, the drying temperature is 40 to 140 ° C., and the drying time can be about 10 to 240 minutes. In particular, when the drying temperature is too low, the amount of residual solvent increases, and bubbles may be generated in the film by the oxidation-reduction reaction. If it is too high, the polymer film may be deteriorated. The drying temperature is more preferably 80 ° C to 120 ° C. In addition, if the drying time is too short, the residual solvent is increased and the film is likely to deteriorate. 30 minutes or more is preferable.

  The coating thickness is 10 nm to 2 μm, preferably 50 to 300 nm after drying. If it is too thin, sufficient color change cannot be obtained. If it is too thick, the response speed tends to deteriorate.

  The color forming layer thus produced by the coating and drying process had a response speed faster than that obtained by the conventional electrolytic polymerization method, and a sufficient color change could be obtained. This is considered to be a film having excellent porosity when applied by a spin coating method or a bar coating method and dried, and is considered to work favorably in responsiveness and color change density. In the present embodiment, the coloring layer is provided on both the transparent electrode 3 and the counter electrode 5, but either one may be used.

(Electrolytes)
Although it does not specifically limit as an ionic liquid used for the electrolyte layer 8, Although it is a liquid at 20 degreeC, A 0.005-0.3Pa * s thing can be used as a viscosity. In particular, those of 0.01 to 0.1 Pa · s are preferable. For example, the following materials can be used. Examples of the anion include compounds having tetrafluoroborate, trifluoromethylsulfonylimide, pentafluoroethylsulfonylimide and the like. In particular, a compound having tetrafluoroborate or trifluoromethylsulfonylimide as an anion is preferable.

  As cations, there are imidazolium cations such as ethylmethylimidazolium and methylbutylimidazolium, pyrrolidinium cations such as butylmethylpyrrolidinium and butylpyridinium, ammonium cations such as butyltrimethylammonium and diethylmethoxyethylmethylammonium, etc. Compounds. In particular, an imidazolium cation or an ammonium cation is preferable as the cation. As the ionic liquid, any combination of these anions and cations can be used. These ionic liquids may be used alone or in combination of two or more. Further, the electrolyte layer 8 containing a liquid electrolyte may be an ionic liquid which is liquid at 20 ° C., but an organic solvent may be used in combination as necessary. When the organic solvent is used in combination, the viscosity of the ionic liquid is lowered, and the response speed may be further improved. Furthermore, the electrolyte layer 8 can also contain a white application pigment as a background color. As such a white pigment, for example, titanium dioxide, calcium carbonate, silica, magnesium oxide, aluminum oxide and the like can be used.

(spacer)
As shown in FIG. 1, the electrochromic display element 1 according to the present invention is provided with a spacer 10 for uniformly holding a gap between the substrates 2 and 4.

  Examples of the spacer 10 include spheres made of a resin, an inorganic oxide, or a hybrid material thereof. Further, a fixed spacer having a surface coated with a thermoplastic resin is also preferably used. The thickness is usually preferably 1 to 200 μm and 5 to 100 μm.

(Seal materials and columnar structures)
As shown in FIG. 1, a sealing material 9 is provided between the transparent substrate 2 and the substrate 4. Although the sealing material is formed in a continuous frame shape around the display area, a columnar structure may be provided in the display area using a resin material similar to the sealing material, and may be used as a spacer.

  When the columnar structure is provided in the display area, for example, a columnar body, a quadrangular columnar body, an elliptical columnar body, a trapezoidal columnar body, a conical columnar body arranged in a predetermined pattern such as a lattice arrangement. It can be set as columnar structures, such as. Alternatively, stripes arranged at predetermined intervals may be used. This columnar structure can appropriately hold the gaps of the substrate, such as an arrangement with equal intervals rather than a random arrangement, an arrangement in which the intervals gradually change, an arrangement in which a predetermined arrangement pattern is repeated at a constant period, etc. The arrangement is preferably considered so as not to disturb the display. If the ratio of the area occupied by the columnar structure 9 in the display region of the electrochromic display element is 1 to 40%, characteristics that are practically satisfactory as a display element can be obtained while maintaining an appropriate strength.

  The resin material for the columnar structure used for the sealing material 9 or spacer for sealing can be used as long as it is a general resin such as epoxy resin, acrylic resin, polyester resin, polyether resin polyethylene resin, polyimide resin, etc. It is.

  Next, the manufacturing method of the sealing material 9 and columnar structure using a polyester resin is demonstrated. For example, first, a polyester resin solution is applied to a roll coater, a gravure coater, or screen printing on either surface of the coloring layer 6 or 7 applied on the transparent electrode 3 or the counter electrode 5 on which a predetermined pattern is formed. After printing using a printing machine such as the like, it is dried and cured.

(Cell formation)
After forming the sealing material 9 and the columnar structure, the transparent substrate 2 and the substrate 4 are overlapped with the electrode forming surfaces facing each other. The pair of substrates are heated while being pressed from both sides to soften the resin material, and then cooled to solidify it again, thereby bonding the two substrates together. In this way, an empty cell that does not yet contain electrolyte is formed.

  In order to use the empty cell as the electrochromic display element 1, the electrolyte 8 may be injected between the transparent substrate 2 and the substrate 4 with the sealing material 9 interposed therebetween, for example, by a vacuum injection method. Alternatively, when the transparent substrate 2 and the substrate 4 are bonded together, the electrolyte may be dropped, and the liquid electrolyte may be sealed simultaneously with the bonding of the substrates.

  Furthermore, in order to improve the accuracy of inter-substrate gap control, when forming the sealing material 9, a spacer 10 having a size smaller than the film thickness of the sealing material 9, such as glass fiber, ball-shaped glass or ceramic powder, or an organic material If the spherical particles made of are arranged so that the gap does not change by heating or pressurization, the gap accuracy can be further improved, and voltage unevenness, display unevenness, etc. can be reduced accordingly.

  The electrochromic display element of the present embodiment has responsiveness far superior to that of the prior art. As a method of detecting the responsiveness of the electrochromic display element, for example, the color change of the color developing layer after voltage application may be measured visually or using a stopwatch, but by using voltammetry or polarography, Quantitative and highly accurate detection is possible. That is, detection by an electrochemical measurement device capable of quantitatively analyzing the relationship between the voltage and current during the oxidation-reduction reaction between the electrodes of the electrochromic display element is preferable. Specific examples of the electrochemical measuring apparatus include a cyclic voltammetric tool HSV-100 manufactured by Hokuto Denko Corporation, and a digital voltammetric analyzer 394 manufactured by Seiko Easy & GE Corporation.

  In the electrochromic display element of this embodiment, when the response speed when a 1.5 V voltage is applied for 2 seconds using a cyclic voltammetry tool HSV-100 manufactured by Hokuto Denko Co., Ltd. is measured, the response speed is 250 msec or less. It has been confirmed that a dramatic high-speed response of 25% or less is possible.

Next, although the performance evaluation experiment of the present Example of the electrochromic display element according to the present invention will be specifically described together with a comparative experiment, the present invention is not limited to these Examples. In this embodiment, the response speed of the display element is used as an evaluation item. This is a quantitative evaluation of the color change of the coloring layer after voltage application. Specifically, while using HSV-100 for voltammetry measurement (manufactured by Hokuto Denko), the produced display element was clip-connected to the HSV-100 and a voltage of 1.5 V was applied for 2 seconds. The time required for the current value to converge to a certain level was defined as the response speed. Therefore, the smaller this value, the better the response.
Example 1
A 10 mm × 10 mm indium tin oxide (ITO) film was formed on a 30 mm × 30 mm transparent glass substrate by sputtering to a thickness of 100 nm. This substrate was set on an Actes spinner, and a polyaniline dispersion (polyaniline sulfonic acid 5 mass%, pure water 95 mass% dispersion: Aqua-PASS Mitsubishi Rayon Co., Ltd.) was dropped onto the electrode side, and 20 at 300 rpm. After rotating for 2 seconds, the rotation speed was increased to 3,000 rpm in 5 seconds, and further rotated for 20 seconds. Two substrates were produced as a display part side and a non-display part side, and then placed in a constant temperature and constant temperature drying apparatus manufactured by Yamato Scientific Co., Ltd. at 80 ° C. for 30 minutes for drying. The film thickness after drying was 200 nm. The two substrates are sandwiched with 10 μm spacers (Micropearl: manufactured by Sekisui Chemical Co., Ltd.) with the electrode sides facing each other, and filled with ionic liquid A composed of BF ₄ ⁻ and butylmethylimidazolium cation, Then, the periphery was sealed with an epoxy resin so that the ionic liquid did not leak, and an electrochromic display element was produced. Thereafter, the response speed and the color change at that time were observed by the measurement method.
Example 2
In Example 1, only the substrate on the non-display portion side was replaced with polyaniline sulfonic acid, and a 2% by weight toluene solution of poly-3-hexylthiophene-2,5-diyl (manufactured by Aldrich) was rotated at 300 rpm for 20 seconds with a spinner. After that, the rotational speed was increased to 3,000 rpm in 5 seconds, and the coating was further rotated for 20 seconds and applied, and the ionic liquid A in Example 1 was used from BF ₄ ⁻ and ethylmethylimidazolium cation. Example 2 was an electrochromic display element produced by the same procedure and formulation except that the ionic liquid B was changed.
Example 3
In Example 1, the polyaniline solution was applied by a bar coating method using a doctor blade with a gap of 20 μm, and the ionic liquid A in Example 1 was ionic liquid B composed of BF ₄ ⁻ and ethylmethylimidazolium cation. Example 3 was an electrochromic display device produced by the same procedure and formulation except that the above was replaced.
Example 4
An electrochromic display element produced in the same procedure and formulation was used in Example 4 except that the ionic liquid A in Example 1 was replaced with the ionic liquid C composed of BF ₄ ^- and diethylmethoxyethylmethylammonium cation.
Example 5
In Example 1, a 2% by weight toluene solution of poly-3-hexylthiophene-2,5-diyl (manufactured by Aldrich) was rotated on a non-display side substrate with a spinner at 300 rpm for 20 seconds, and after 3 seconds in 3 seconds. Increase the rotation speed to 1,000,000 rpm, rotate for another 20 seconds,
Example 5 An electrochromic display element produced in the same manner as in Example 5 except that ionic liquid D consisting of (CF ₃ SO ₂ ) ₂ N ⁻ and ethylmethylimidazolium cation was used instead of ionic liquid A It was.
Example 6
In Example 1, a polyaniline solution was applied by a bar coating method using a doctor blade with a gap of 20 μm, and instead of ionic liquid A, (CF ₃ CF ₂ SO ₂ ) ₂ N ⁻ and ethylmethylimidazolium cation were used. Example 6 was an electrochromic display element produced in the same manner except that the ionic liquid E was used.
Example 7
In Example 1, a polyaniline solution was applied by a bar coating method using a doctor blade with a gap of 20 μm, and ionic liquid F consisting of BF ₄ ⁻ and butyltrimethylammonium cation was used instead of ionic liquid A. An electrochromic display element produced in the same manner was designated as Example 7.
Comparative Example 1
In Example 1, an electrochromic display element produced by the same procedure and formulation was used as Comparative Example 1, except that the electrolytic polymerization method was used as a method for producing the conductive polymer film. As an electrolytic polymerization method at this time, a substrate in which the ITO film of Example 1 was formed as a working electrode in an aqueous solution obtained by adding 0.5 M aniline to 1 M HCl, platinum foil as a counter electrode, and as a reference electrode A black aniline film was prepared by using Ag / AgCl and applying 2 mV between the electrodes for 15 minutes.
Comparative Example 2
In Example 1, the electropolymerization method was used as a method for producing the conductive polymer film, and the ionic liquid A was replaced with the ionic liquid C composed of BF ₄ ^- and diethylmethoxyethylmethylammonium cation. The electrochromic display element produced by the above procedure and formulation was referred to as Comparative Example 2. As the electrolytic polymerization method, the same method as in Comparative Example 1 was used.
Comparative Example 3
In Example 1, the same procedure was used except that an electropolymerization method was used as a method for producing the conductive polymer film, and the ionic liquid A was replaced with the ionic liquid F composed of BF ₄ ^- and butyltrimethylammonium cation. The electrochromic display element produced by the prescription was referred to as Comparative Example 3. As the electrolytic polymerization method, the same method as in Comparative Example 1 was used.
Comparative Example 4
In Example 1, instead of polyaniline dispersion, polymethyl methacrylate (PMMA) powder was added to toluene at a ratio of 1: 1, and fluoran dye GreenDCF (manufactured by Hodogaya Chemical Co., Ltd.) was added at 5 mass%. The electrochromic display element produced in the same manner was used as Comparative Example 4 except that the added mixed solution was used and the drying condition after coating was 60 ° C.
Comparative Example 5
An electrochromic display device produced in the same procedure and formulation was used in Example 5 except that the ionic liquid A in Example 1 was replaced with a 1 mol / L LiClO ₄ propylene carbonate solution.
Comparative Example 6
As the electrolyte layer in Example 1, a sheet produced by the following manufacturing method was used. Polyvinylidene fluoride (2 g) and 1 mol / L of (CF ₃ SO ₂ ) ₂ N ^- and 5 g of propylene carbonate solution of ionic liquid B consisting of ethylmethylimidazolium cation were mixed and diluted with acetone to obtain a uniform solution. . This solution was applied onto a tetrafluoroethylene substrate by a doctor blade method, dried by heating, and the solvent was blown off to obtain a uniform ion conductive sheet having a thickness of 50 μm. An electrochromic display element produced by the same procedure and formulation as in Example 1 except that this sheet was used as the electrolyte layer was used as Comparative Example 6.

  Table 1 shows the ionic liquid, conductive polymer, coating method, and response speed of the coloring layer after voltage application for Examples 1 to 7 and Comparative Examples 1 to 6.

  As shown in Table 1, Examples 1 to 7 which are electrochromic display elements according to the present invention have a response speed of 250 msec or less, and are markedly higher than Comparative Examples 1 to 6 in which the response speed is 500 msec or more. It was confirmed to have excellent responsiveness.

1 is a schematic basic configuration diagram of an embodiment of an electrochromic display element according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrochromic display element 2 Transparent substrate 3 Transparent electrode 4 Substrate 5 Counter electrode 6, 7 Conductive polymer film 8 Electrolyte layer 9 Sealing material 10 Spacer 11, 12 Lead wire 20 Power supply

Claims (6)

In an electrochromic display element in which a coloring layer made of a conductive polymer and an electrolyte layer containing a liquid electrolyte are provided between a transparent electrode and a counter electrode, the liquid electrolyte is a liquid ionic liquid at 20 ° C. The electrochromic display element is characterized in that the color-developing layer is formed by applying and drying a liquid containing a conductive polymer on the transparent electrode and / or the counter electrode. The electrochromic display element according to claim 1, wherein the coating is spin coating or bar coating. The electrochromic display element according to claim 1, wherein the ionic liquid is a compound having BF ₄ ⁻ . The electrochromic display element according to claim 1, wherein the ionic liquid is a compound having an anion having the following structure.
(CF ₃ (CF ₂ ) _n SO ₂ ) ₂ N ⁻ (where n represents 0 or 1) The electrochromic display element according to claim 1, wherein the ionic liquid is a compound having an ammonium cation. The electrochromic display element according to claim 1, wherein the ionic liquid is a compound having an imidazolium cation.

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