Electrochromic device and apparatus using the same

Abstract

To provide a complementary organic EC device that avoids a side reaction between reactants generated by a pair of electrodes and is provided with memory properties to achieve low power consumption.SOLUTION: An EC device has a separator 4 that divides the gap between electrodes 2a, 2b equally into two, and a pair of EC layers 3a, 3b arranged across the separator 4. A separator, which is used as the separator 4, has an ion resistance in a thickness direction of 50 Ωcm2 or more and 300 Ωcm2 or less when it is immersed in a 0.1 M tetrabutyl ammonium TFSI / propylene carbonate solution.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an electrochromic element and a device constructed using the electrochromic element. [Background technology]

[0002] An electrochromic (hereinafter sometimes referred to as "EC") element is an element having a pair of electrodes and an EC layer disposed between the electrodes. It is an active optical element that adjusts the hue and light quantity in the visible light range by applying a voltage between the pair of electrodes to oxidize or reduce a compound in the EC layer. To date, EC elements have been gradually used as light-control windows in homes and aircraft. However, in recent years, growing demand for environmentally friendly windows has created a demand for the development of larger-area, lower-power-consumption light-control windows that maintain the performance of conventional elements. EC elements using organic EC compounds have the characteristics that the light intensity can be adjusted over a wide range and color design is relatively easy. Furthermore, when considering the coloring efficiency (the amount of change in optical density divided by the required amount of charge), it is preferable that an electrochemically active anodic material and an electrochemically active cathodic material are included between the pair of electrodes in a complementary manner, and both of them have EC properties. In addition, in order to realize a high-speed response, it is necessary for a large amount of organic EC compounds to react on the electrode surface per unit time, and therefore it is preferable to configure the EC layer as a solution or gel so that the organic EC compounds can move freely inside the EC layer. However, when such a configuration is adopted, the anodic and cathodic organic EC compounds that react at the pair of electrodes undergo charge exchange (side reaction) inside the EC layer and relax to a neutral state. Therefore, it is necessary to continuously apply electricity to maintain the optical density, which has been an obstacle to reducing the power consumption of complementary organic EC elements. Patent Document 1 discloses an element structure in which a selectively permeable membrane that is permeable to electrolyte ions but not to reactant molecules is provided in an EC layer in a complementary organic EC element, thereby avoiding side reactions between reactants generated at a pair of electrodes. Furthermore, Patent Document 2 discloses an element structure in which a selectively permeable membrane that realizes a light transmittance of 80% or more in a complementary organic EC element is used to avoid side reactions between reactants generated at a pair of electrodes. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Pat. No. 3,453,038 [Patent Document 2] U.S. Pat. No. 1,099,6536 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-mentioned conventional technology, the requirements for the selectively permeable membrane that separates the EC layer into two compartments, i.e., the requirements regarding transparency and the requirements for preventing side reactions and reducing power consumption, are unclear. Furthermore, the effect of reducing power consumption in Patent Document 2 cannot be said to be sufficient. In view of the above problems, the present invention aims to avoid side reactions between reactants generated at a pair of electrodes in a complementary organic EC element, impart memory properties to the element, realize low power consumption, and further impart excellent transparency in a neutral state. [Means for solving the problem]

[0005] The present invention provides an electrochromic device comprising a first electrode, a second electrode, a separator bisecting a gap between the first electrode and the second electrode, a first electrochromic layer disposed between the first electrode and the separator and including at least one cathodic electrochromic compound, and a second electrochromic layer disposed between the second electrode and the separator and including at least one anodic electrochromic compound, The ionic resistance of the separator in the thickness direction when impregnated with 0.1M tetrabutylammonium TFSI / propylene carbonate solution is 50Ωcm.2 More than 300Ωcm 2 The present invention is characterized in that: Effect of the Invention

[0006] According to the present invention, since memory properties can be obtained when colored, low power consumption can be achieved. Furthermore, by limiting the average fiber diameter of the separator, an EC element with excellent transparency when neutral can be realized. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic cross-sectional view showing one embodiment of an EC element of the present invention. [Diagram 2] FIG. 2 is a schematic diagram showing an example of a driving device including an EC element of the present invention. [Diagram 3] 1A and 1B are schematic diagrams illustrating an example of an imaging device in which an optical filter is disposed in a lens unit and in which an optical filter is disposed in the imaging device, respectively. [Figure 4] 1A and 1B are an overview diagram showing a window material using an EC element according to an embodiment of the present invention, and a schematic cross-sectional view in the thickness direction thereof. [Diagram 5] 1 is a graph plotting the optical density change ΔOD550 versus the ionic resistance R of each separator. [Figure 6] 1 is a graph plotting the optical density change ΔOD550 versus the tortuosity τ of each separator. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] The electrochromic element of the present invention is an EC element having a pair of electrochromic layers sandwiching the separator, with the gap between the electrodes being divided into two by the separator. The EC element of the present invention is a complementary EC element in which one of the pair of EC layers contains at least a cathodic electrochromic compound and the other contains at least an anodic electrochromic compound, and the ionic resistance of the separator is specified to impart memory properties during coloring and reduce power consumption. In the present invention, excellent transparency can also be obtained by limiting the average fiber diameter of the separator. Hereinafter, the configuration of the EC element according to the present invention will be described in detail as an example of a preferred embodiment with reference to the drawings. However, the configuration, relative arrangement, and the like described in the embodiment are not intended to limit the scope of the present invention unless otherwise specified.

[0009] <EC element> First, the configuration of the EC element of the present invention will be described with reference to FIG. 1. FIG. 1 is a cross-sectional schematic diagram in the thickness direction showing the configuration of one embodiment of the EC element 6 of the present invention. In FIG. 1, 1a and 1b are a pair of substrates, and a pair of electrodes 2a and 2b are formed on one side of the substrates 1a and 1b on the inner side of the element. Furthermore, EC layers 3a and 3b are provided in contact with the electrodes 2a and 2b, respectively, and the EC layers 3a and 3b are partitioned by a separator 4. In addition, a seal 5 is provided on the outer periphery of the element so as to surround the EC layers 3a and 3b. Hereinafter, for convenience, the substrate 1a will be referred to as the first substrate, the substrate 1b as the second substrate, the electrode 2a as the first electrode, the electrode 2b as the second electrode, the EC layer 3a as the first EC layer, and the EC layer 3b as the second EC layer.

[0010] Next, the members constituting the EC element of the present invention will be described in detail. The pair of substrates 1a and 1b are transparent substrates, and are required to be made of an electrical insulator such as glass or resin, have high transparency, excellent heat resistance, and high chemical stability. As glass, optical glass, quartz glass, white plate glass, blue plate glass, borosilicate glass, alkali-free glass, chemically strengthened glass, etc. can be used, and in particular, alkali-free glass is preferably used in terms of transparency and durability. As resin, polycarbonate (PC), acrylic (PMMA), polyethylene terephthalate (PET), transparent polyimide (PI), etc. can be used. In addition, it is preferable to use those having a hard coat layer formed on the surface of these resins to improve scratch resistance.

[0011] A transparent conductive material is used for the pair of electrodes 2a, 2b, and examples of such materials include indium tin oxide (ITO), fluorine-doped tin oxide (FTO), tin oxide (NESA), indium zinc oxide (IZO), graphene, etc. In addition, conductive polymers whose conductivity has been improved by doping treatment or the like, such as polyaniline, polypyrrole, polythiophene, polyacetylene, polyparaphenylene, and a complex of polyethylenedioxythiophene (PEDOT) and polystyrenesulfonic acid, are also preferably used.

[0012] The pair of EC layers 3a, 3b separated by the separator 4 is preferably a solution in which an EC compound is dissolved in an organic solvent, or a gel, and may contain an electrolyte. In addition, a spacer having a function of defining the distance between the first electrode 2a and the separator 4 and the distance between the second electrode 2b and the separator 4 may be included. The spacer may be made of an inorganic material such as silica beads or glass fiber, or an organic material such as polydivinylbenzene, polyimide, polytetrafluoroethylene, fluororubber, or epoxy resin.

[0013] Methods for forming the EC layers 3a, 3b include a method of injecting a liquid containing an EC compound prepared in advance into the gap between the pair of electrodes 2a, 2b and the separator 4 by vacuum injection, air injection, meniscus method, etc., a method of dropping a liquid containing an EC compound by the ODF method and then vacuum laminating it together with the separator 4, and a method of coating the pair of electrodes 2a, 2b by blade coating, bar coating, slit die coating, etc., and then laminating it together with the separator 4.

[0014] The EC compounds are preferably organic compounds, and the first EC layer 3a contains at least one cathodic electrochromic compound that changes color from a transparent state by a reduction reaction, and the second EC layer 3b contains at least one anodic electrochromic compound that changes color from a transparent state by an oxidation reaction. A device having both an anodic EC compound and a cathodic EC compound is called a complementary EC device, and the anodic EC compound is also called an anode material, and the cathodic compound is also called a cathode material.

[0015] When the complementary EC element is driven, an electron is extracted from the EC compound by an oxidation reaction at one electrode, and an electron is received by the EC compound by a reduction reaction at the other electrode. A radical cation may be generated from a neutral molecule by an oxidation reaction. Alternatively, a radical anion may be generated from a neutral molecule by a reduction reaction, or a radical cation may be generated from a dicationic molecule. In the present invention, the EC compound is colored at both of the pair of electrodes 2a and 2b, and a large change in optical density is obtained when the EC compound is colored. Examples of the organic EC compound include conductive polymers such as polythiophene and polyaniline, viologen-based compounds, anthraquinone-based compounds, oligothiophene derivatives, and phenazine derivatives, as well as other organic low molecular weight compounds.

[0016] In the present invention, the first EC layer 3a may contain one or more anodic EC compounds, and the second EC layer 3b may contain one or more cathodic EC compounds, or the EC layers 3a and 3b may be made of the same composition containing one or more anodic EC compounds and one or more cathodic EC compounds.

[0017] When the EC layers 3a and 3b contain multiple types of EC compounds, it is preferable that the difference in redox potential between the EC compounds is small. When multiple types of EC compounds are present, the anodic and cathodic compounds may be combined to form a total of four or more types of EC compounds, or five or more types of EC compounds. When multiple types of EC compounds are present, the redox potential of the multiple anodic materials is preferably within 60 mV, and the redox potential of the multiple cathodic materials is preferably within 60 mV. When multiple types of EC compounds are present, the multiple EC compounds may include a compound having an absorption peak from 400 nm to 500 nm, a compound having an absorption peak from 500 nm to 650 nm, and a compound having an absorption peak above 650 nm. The absorption peak refers to a peak with a half-width of 20 nm or more. In addition, the state of the material when absorbing light may be an oxidized state, a reduced state, or a neutral state.

[0018] The electrolyte that may be contained in the EC layers 3a and 3b is not limited as long as it is an ion-dissociating salt and has good solubility in a solvent and high compatibility with a solid electrolyte. Among them, an electrolyte having electron-donating properties is preferable. These electrolytes can also be called supporting electrolytes. Examples of the electrolyte include inorganic ion salts such as various alkali metal salts and alkaline earth metal salts, quaternary ammonium salts, and cyclic quaternary ammonium salts. Specific examples include alkali metal salts of Li, Na, and K, such as LiClO4, LiSCN, LiBF4, LiAsF6, LiCF3SO3, LiPF6, LiI, NaI, NaSCN, NaClO4, NaBF4, NaAsF6, KSCN, and KCl, as well as quaternary ammonium salts and cyclic quaternary ammonium salts, such as (CH3)4NBF4, (C2H5)4NBF4, (n-C4H9)4NBF4, (n-C4H9)4NPF6, (C2H5)4NBr, (C2H5)4NClO4, and (n-C4H9)4NClO4.

[0019] The solvent for dissolving the EC compound and the electrolyte is not particularly limited as long as it can dissolve the EC compound and the electrolyte, but it is particularly preferable to use a solvent having polarity.Specific examples of the solvent include water and organic polar solvents such as methanol, ethanol, propylene carbonate, ethylene carbonate, dimethyl sulfoxide, dimethoxyethane, γ-butyrolactone, γ-valerolactone, sulfolane, dimethylformamide, dimethoxyethane, tetrahydrofuran, acetonitrile, propiononitrile, 3-methoxypropiononitrile, benzonitrile, dimethylacetamide, methylpyrrolidinone, and dioxolane.

[0020] The EC layers 3a and 3b may further contain a polymer matrix, a gelling agent, and a crosslinking agent. In this case, the EC layers 3a and 3b may be made into a gel (physical gel) from a highly viscous liquid by adding only a polymer, or into a gel (chemical gel) by adding a crosslinking agent to a polymer matrix. Examples of polymers include polyacrylonitrile, carboxymethylcellulose, pullulan-based polymers, polyvinyl chloride, polyethylene oxide, polypropylene oxide, polyurethane, polyacrylate, polymethacrylate, polyamide, polyacrylamide, polyester, polyvinylpyridine, Nafion (registered trademark), and the like.

[0021] The seal 5 is preferably made of a material that is chemically stable, impermeable to gases and liquids, and does not inhibit the redox reaction of the EC compound, such as inorganic materials such as glass frit, and organic materials such as epoxy resin.

[0022] The separator 4 is preferably made of nanofibers, and in order to ensure transparency in the visible light region, nanocellulose (cellulose nanofiber, hereinafter sometimes referred to as "CNF") having a fiber diameter of 10 nm or less is particularly preferred. Specifically, it is preferable that the light transmittance at a wavelength of 550 nm is 80% or more.

[0023] Here, the requirements for the separator of the EC element of the present invention that realizes low power consumption will be described in detail. The separator 4 is a selectively permeable membrane that does not allow the EC compound to pass through but allows electrolyte ions to pass through, preventing contact between the excited cathodic EC compound contained in the first EC layer 3a and the anodic EC compound contained in the second EC layer 3b, thereby suppressing cross-reactions (side reactions) between them, thereby enabling the EC element 6 to consume less power. The separator 4 can be defined by various physical property values, but can be preferably defined by direct physical property parameters related to the porous structure, such as ionic resistance and tortuosity. The ionic resistance R can be evaluated by measuring the impedance in the thickness direction of the separator 4 impregnated with an electrolyte solution, and the tortuosity τ is defined by the following formula [1] as the ratio of the effective path length to the thickness of the separator 4.

[0024] τ=l / d=((R ε) / (ρ d)) 1 / 2 [1] l: Effective path length in the thickness direction of the separator 4 (m) d: thickness of separator 4 (m) R: Ion resistance (Ωcm 2 ) ε: Porosity ρ: resistivity of the electrolyte solution (Ω)

[0025] The separator 4 suppresses cross-reaction between the excited anodic EC compound and the excited cathodic EC compound, but the resistance of the separator 4 limits the electrode reaction between the electrodes 2a and 2b. In the present invention, the ionic resistance R of the separator 4 in the thickness direction is 50 Ω cm. 2 More than 300Ωcm 2 If the ionic resistance R is less than 50 Ωcm, the electrode reaction between the electrodes 2a and 2b becomes more dominant than the cross reaction between the excited anodic EC compound and the excited cathodic EC compound, and the colored state is efficiently maintained. 2 More than 150Ωcm 2 The following is preferable: As the electrolyte solution for measuring the ionic resistance R, a 0.1 M tetrabutylammonium TFSI / propylene carbonate solution (TFSI: trisfluoromethanesulfonylimide) is used.

[0026] For the same reason as for the ionic resistance R, the tortuosity τ of the separator 4 is preferably 1.5 to 4.5, and in consideration of the responsiveness of the EC element 6, the tortuosity τ is preferably 1.5 to 3.0.

[0027] <Use of the EC element> The EC element according to this embodiment can be used in an optical filter, a lens unit, an imaging device, a window material, or the like.

[0028] 〔Optical filter〕 The optical filter according to this embodiment includes the EC element according to the present invention and an active element connected to the EC element. The active element is an active element that drives the EC element and adjusts the amount of light passing through the EC element. Examples of the active element include a transistor. The transistor may have an oxide semiconductor such as InGaZnO in the active region.

[0029] The optical filter according to this embodiment has a driving device connected to the EC element according to the present invention. FIG. 2 is a schematic diagram showing an example of the driving device 20 of the EC element and the EC element 6 driven by the driving device 20. The driving device 20 of the optical filter according to this embodiment includes a driving power source 8, a resistance switch 9, and a controller 7.

[0030] The driving power source 8 applies a voltage necessary for the EC material contained in the EC layer to cause an electrochemical reaction to the EC element. The driving voltage is more preferably a constant voltage. This is because when the EC material is composed of a plurality of types of materials, the absorption spectrum may change due to the difference in the oxidation-reduction potential difference or molar absorption coefficient of the materials, so a constant voltage is preferred. The start or retention of the voltage application of the driving power source 8 is performed by a signal from the controller 7, and the constant voltage application state is retained during the period of controlling the light transmittance of the EC element 6.

[0031] The controller 7 controls the transmittance of the EC element 6 in a manner suited to the element being used. Specifically, this can be achieved by inputting predefined conditions to the EC element 6 for a desired set value of transmittance, or by comparing the set value of transmittance with the transmittance of the EC element 6 and selecting and inputting conditions that match the set value. Examples of parameters that can be changed include the voltage, current, and duty ratio. The controller 7 can change the coloring density of the EC element 6 by changing the voltage, current, or duty ratio.

[0032] In this embodiment, known means can be used to change the voltage, change the current, and modulate the pulse width. The pulse width can also be modulated as follows. The resistance switch 9 switches between a resistor R1 (not shown) and a resistor R2 larger than the resistor R1 and connects them in series in a closed circuit including the driving power supply 8 and the EC element 6. The resistance value of the resistor R1 is preferably smaller than the largest impedance of the element closed circuit, and is preferably 10Ω or less. The resistance value of the resistor R2 is preferably larger than the largest impedance of the element closed circuit, and is preferably 1MΩ or more. The resistor R2 may be air. In this case, strictly speaking, the closed circuit becomes an open circuit, but it can be considered as a closed circuit by regarding the air as the resistor R2. The controller 7 sends a switching signal to the resistor switch 9 to control the switching of the resistors R1 and R2. However, without the resistor switch 9, the PWM signal may be generated using a comparator or the like.

[0033] [Lens unit] The lens unit according to the present embodiment includes an imaging optical system having a plurality of lenses and an optical filter having the EC element of the present invention. The optical filter may be provided either between the plurality of lenses or outside the lens. The optical filter is preferably provided on the optical axis of the lens.

[0034] [Imaging device] The imaging device of this embodiment has an optical filter and a light receiving element that receives light that has passed through the optical filter. Specific examples of imaging devices include cameras, video cameras, and mobile phones with cameras. The imaging device may be in a form in which a main body having a light receiving element and a lens unit having a lens can be separated. In this case, when the imaging device can be separated into a main body and a lens unit, the present invention also includes a form in which an optical filter separate from the imaging device is used during imaging. In this case, the optical filter may be disposed outside the lens unit, between the lens unit and the light receiving element, between multiple lenses (when the lens unit has multiple lenses), and the like.

[0035] FIG. 3(a) is a schematic diagram of an example of an imaging device in which an optical filter is disposed in a lens unit, and FIG. 3(b) is a schematic diagram of an example of an imaging device in which an optical filter is disposed in the imaging device.

[0036] The imaging device 100 includes a lens unit 102 and an imaging unit 103. The lens unit 102 includes an imaging optical system including an optical filter 101 and a plurality of lenses or a lens group. The optical filter 101 is an optical filter including the EC element of the present invention according to the above-described embodiment.

[0037] 3(a), the lens unit 102 represents, for example, a rear-focus type zoom lens that performs focusing behind the aperture. It has four lens groups, in order from the object side, a first lens group 104 with positive refractive power, a second lens group 105 with negative refractive power, a third lens group 106 with positive refractive power, and a fourth lens group 107 with positive refractive power. Magnification is changed by changing the distance between the second lens group 105 and the third lens group 106, and focusing is performed by moving a part of the lens groups in the fourth lens group 107.

[0038] The lens unit 102 has, for example, an aperture stop 108 between the second lens group 105 and the third lens group 106, and also has an optical filter 101 between the third lens group 106 and the fourth lens group 107. The lens unit is arranged so that light passing through each of the lens groups 104 to 107, the aperture stop 108, and the optical filter 101 passes through, and the amount of light can be adjusted using the aperture stop 108 and the optical filter 101. The lens unit 102 is detachably connected to the imaging unit 103 via a mount member (not shown).

[0039] In this embodiment, the optical filter 101 is disposed between the third lens group 106 and the fourth lens group 107 in the lens unit 102, but the imaging device 100 is not limited to this configuration. For example, the optical filter 101 may be disposed either in front of (on the subject side) or behind (on the imaging unit 103 side) the aperture stop 108, or may be disposed in front of, behind, or between any of the first to fourth lens groups 104 to 107. If the optical filter 101 is disposed at a position where light converges, there is an advantage in that the area of ​​the optical filter 101 can be reduced.

[0040] The configuration of the lens unit 102 is not limited to the above configuration, and can be selected as appropriate. For example, in addition to the rear focus type, it may be an inner focus type in which focusing is performed in front of the aperture, or other types. In addition to the zoom lens, special lenses such as a fisheye lens or a macro lens can also be selected as appropriate.

[0041] The imaging unit 103 has a glass block 109 and a light receiving element 110. The glass block 109 is a glass block such as a low-pass filter, a face plate, or a color filter. The light receiving element 110 is a sensor unit that receives light that has passed through a lens unit, and an imaging element such as a CCD or CMOS can be used. Alternatively, it may be an optical sensor such as a photodiode, and it is possible to appropriately use one that obtains and outputs information on the intensity or wavelength of light.

[0042] 3(a), when the optical filter 101 is incorporated in the lens unit 102, the driving device may be disposed inside or outside the lens unit 102. When disposed outside the lens unit 102, the EC element 6 in the lens unit 102 is connected to the driving device through a wire to control driving.

[0043] In the configuration of the imaging device 100 described above, the optical filter 101 is disposed inside the lens unit 102. However, the present invention is not limited to this configuration, and it is sufficient that the optical filter 101 is disposed at an appropriate location inside the imaging device 100, and the light receiving element 110 is disposed so as to receive light that has passed through the optical filter 101.

[0044] For example, as shown in Fig. 3(b), the imaging unit 103 may have the optical filter 101. Fig. 3(b) is a diagram for explaining the configuration of another example of the imaging device of this embodiment, and is a schematic diagram of the configuration of an imaging device having an optical filter in the imaging unit 103. In Fig. 3(b), for example, the optical filter 101 is disposed immediately before the light receiving element 110. When the imaging device itself has the optical filter 101 built in, the connected lens unit 102 itself does not need to have the optical filter 101, so it is possible to configure a dimmable imaging device using an existing lens unit 102.

[0045] The imaging device 100 of this embodiment can be applied to products that have a combination of light amount adjustment and a light receiving element. For example, it can be used in cameras, digital cameras, video cameras, and digital video cameras, and can also be applied to products that have an imaging device built in, such as mobile phones, smartphones, PCs, and tablets.

[0046] According to the imaging device 100 of this embodiment, by using the optical filter 101 as a light adjusting component, it is possible to appropriately change the amount of light adjustment with one filter, which has the advantages of reducing the number of components and saving space.

[0047] [Window materials] The window material according to the present embodiment includes an EC element according to the present invention and an active element connected to the EC element. The active element drives the EC element and adjusts the amount of light passing through the EC element. The active element may be, for example, a transistor. The transistor may have an oxide semiconductor such as InGaZnO in an active region. The window material according to the present embodiment may also be called a variable transmittance window.

[0048] Fig. 4(a) is an overview diagram showing a light control window as a window material using an EC element according to the present invention, and Fig. 4(b) is a schematic diagram showing a cross section in the thickness direction of the center part (X-X') of the light control window in Fig. 4(a). The light control window 111 of this embodiment is composed of an EC element (optical filter), transparent plates 113, 113 that sandwich it, and a frame 112 that surrounds and integrates the whole. The EC element has the configuration shown in Fig. 1 and has a driving device (not shown), which may be integrated within the frame 112, or may be arranged outside the frame 112 and connected to the EC element 6 through wiring.

[0049] There are no particular limitations on the material of the transparent plate 113 as long as it has a high light transmittance, and a glass material is preferable in consideration of use as a window material. The material of the frame 112 is not important, but anything that covers at least a part of the EC element 6 and has an integrated form may be regarded as a frame. In Fig. 4, the EC element 6 is a component independent of the transparent plate 113, but for example, the substrates 1a and 1b of the EC element 6 may be regarded as the transparent plates 113, 113.

[0050] Such a light-control window can be used, for example, to adjust the amount of sunlight entering a room during the day. Since it can be used to adjust not only the amount of sunlight but also the amount of heat, it can be used to control the brightness and temperature inside a room. It can also be used as a shutter to block the view from outside to inside the room. In addition to glass windows for buildings, such light-control windows can also be used as window materials for vehicles such as automobiles, trains, airplanes, and ships. Thus, the EC element of the present invention can be used in optical filters, lens units, imaging devices, window materials, and the like.

[0051] Moreover, an electrochromic mirror can be formed by providing a reflective member on one of the light paths of the EC element. The EC mirror may be provided in an automobile as an anti-glare mirror. The EC mirror can be configured by having an electrochromic element and a reflective member inside or outside the EC element. Having a reflective member inside means that the electrodes of the EC element are reflective. Having a reflective member outside means that a reflective member is provided in contact with the electrodes of the EC element or via another transparent member.

[0052] ≪Included components≫ The disclosure of this embodiment includes the following configuration. (Configuration 1) 1. An EC device comprising: a first electrode, a second electrode, a separator bisecting a gap between the first electrode and the second electrode, a first EC layer disposed between the first electrode and the separator and including at least one cathodic EC compound, and a second EC layer disposed between the second electrode and the separator and including at least one anodic EC compound, The ionic resistance of the separator in the thickness direction when impregnated with 0.1M tetrabutylammonium TFSI / propylene carbonate solution is 50Ωcm. 2 More than 300Ωcm 2 An EC element characterized in that: (Configuration 2) 2. The EC element according to configuration 1, wherein the separator is made of nanofibers. (Configuration 3) 3. The EC element according to configuration 2, wherein the separator made of nanofibers has an average fiber diameter of 10 nm or less. (Configuration 4) 4. An EC element according to configuration 2 or 3, characterized in that the nanofibers are made of nanocellulose. (Configuration 5) 5. The EC element according to any one of configurations 1 to 4, wherein the separator has a tortuosity of 1.5 or more and 4.5 or less. (Configuration 6) 6. The EC element according to any one of configurations 1 to 5, wherein the separator has a light transmittance of 80% or more at a wavelength of 550 nm.

[0053] (Configuration 7) 7. An optical filter comprising: an EC element according to any one of configurations 1 to 6; and a transistor connected to the EC element. (Configuration 8) A lens unit comprising the optical filter according to configuration 7 and an imaging optical system having a plurality of lenses. (Configuration 9) 8. An imaging device comprising: the optical filter according to claim 7; and a light receiving element that receives light that has passed through the optical filter. (Configuration 10) 7. A window material comprising: an EC element according to any one of configurations 1 to 6; and a transistor connected to the EC element. (Configuration 11) 7. An EC mirror comprising: an EC element according to any one of configurations 1 to 6; and a reflecting member disposed inside or outside the EC element. EXAMPLES

[0054] Table 1 shows the physical properties of the separators used in this example. The thickness of each separator is 20 μm, and the light transmittance is a value at a wavelength of 550 nm. It can be seen that No. 2 to No. 5, which have an average fiber diameter of 10 nm or less, have high transparency, and that even if the average fiber diameter is the same, there are differences in ionic resistance and tortuosity.

[0055] [Table 1]

[0056] Example 1 An EC element was fabricated by ODF and vacuum lamination using separator No. 2 shown in Table 1 and an ITO glass substrate with a sheet resistance of 10 Ω / □. The layer thickness of the pair of EC layers was determined by kneading gap control particles with a diameter of 40 μm. Each EC layer contains the anodic EC compound and cathodic EC compound below, and propylene carbonate as a solvent, and is a chemical gel crosslinked with polyvinylpyridine polymer. The composition of the pair of EC layers is the same. The light control area of ​​the element was 20 mm x 20 mm, and the outer periphery was sealed with epoxy resin.

[0057] Anodic EC Compound: MOPOPhO1MedMdHPhzn: 3-(2-isoproxy-6-methoxyphenyl)-1,5,10-trimethyl-8-phenoxy-5,10-dihydrophenazine mMeOPhO1MediPrdHPhzn: 5,10-diisopropyl-2-(3-methoxyphenoxy)-7-methyl-5,10-dihydrophenazine Cathodic EC Compounds: F3BuAFlu2TFSI: 9,9-dimethyl-2,7-bis(4,4,4-trifluorobutyl)-9H-cyclopenta[1,2-c:4,3-c']dipyridinium bis[bis(trifluoromethanesulfonyl)imide] pdtBuPh3MeVTFSI: 1,1'-bis(4-tert-butyl)phenyl-3-methyl-4,4'-dipyridinium bis[bis(trifluoromethanesulfonyl)imide]

[0058] The above four EC compounds were contained in the EC layer at the following concentrations. MOPOPhO1MedMdHPhzn:27mM mMeOPhO1MediPrdHPhzn: 351 mM F3BuAFlu2TFSI:284mM pdtBuPh3MeVTFSI:94mM

[0059] When a constant voltage of 0.55 V was applied to the obtained EC element, the light transmittance at a wavelength of 550 nm dropped from 76.2% to 1.0% in 153 seconds. When the voltage was further applied for 180 seconds and the light transmittance reached 0.70%, the circuit was opened, and the light transmittance after 1 hour was 1.34% (optical density change ΔOD 550 =-0.28) and the coloring remained unchanged (has memory properties).

[0060] Example 2 An EC element was prepared in the same manner as in Example 1, except that separator No. 3 shown in Table 1 was used. When a constant voltage of 0.55 V was applied to the obtained EC element, the light transmittance at a wavelength of 550 nm dropped from 80.4% to 1.0% in 166 seconds. When a voltage was further applied for 180 seconds, and the light transmittance reached 0.81%, the circuit was opened, and the light transmittance after 1 hour was 1.21% (change in optical density ΔOD 550 =-0.17) and the coloring remained unchanged (has memory properties).

[0061] Comparative Example 1 An EC element was prepared in the same manner as in Example 1, except that separator No. 1 shown in Table 1 was used. When a constant voltage of 0.55 V was applied to the obtained element, the current became substantially constant in about 60 seconds, and the light transmittance at a wavelength of 550 nm dropped from 18.2% to 5.4%. When a voltage was further applied for 180 seconds, and the light transmittance reached 4.6%, the circuit was opened, and the initial transmittance was restored in about 90 seconds (optical density change ΔOD 550 =-0.60 (no memory).

[0062] Separator No. 1 had a large average fiber diameter of 3.2 μm, which not only scattered visible light and impaired the transparency of the EC element, but also had too low ionic resistance R to exhibit memory properties, requiring a large amount of power to maintain the colored state.

[0063] (Comparative Examples 2, 3, and 4) An EC element of Comparative Example 2 was prepared in the same manner as in Example 1, except that no separator was used. In addition, EC elements of Comparative Examples 3 and 4 were prepared in the same manner as in Example 1, except that separators No. 4 and 5 shown in Table 1 were used.

[0064] The optical density change ΔOD at a wavelength of 550 nm when a constant voltage of 0.55 V was applied for 3 minutes to the obtained EC element and each of the EC elements of Examples 1 and 2 and Comparative Example 1 was 550 A graph in which the change in optical density ΔOD 550 is larger than those in Comparative Examples 1 and 2. This indicates that the electrode reaction is dominant over the charge exchange reaction (side reaction), and the colored state can be efficiently maintained. In the EC elements of Comparative Examples 3 and 4, the ionic resistance R of the separator is large, which limits the electrode reaction, and therefore the optical density change ΔOD 550 Therefore, the ionic resistance R in the thickness direction of the separator is 50 Ω cm 2 More than 300Ωcm 2 The following is the result.

[0065] In addition, for each of the EC devices in Examples 1 and 2 and Comparative Examples 1 to 4, the change in optical density ΔOD at a wavelength of 550 nm when a constant voltage of 0.55 V was applied for 3 minutes was 550 A graph in which the above is plotted against the separator tortuosity τ is shown in Figure 6. It can be seen that the separator tortuosity τ is also preferably 1.5 or more and 4.5 or less.

[0066] Table 2 shows the change in optical density ΔOD at a wavelength of 550 nm when a constant voltage of 0.55 V was applied for 3 minutes for each of the EC devices in Examples 1 and 2 and Comparative Examples 1 to 4. 550 The change in optical density ΔOD indicates whether the ink has a memory function or not. 550 The relative values ​​in the column are the optical density change ΔOD of Comparative Example 2. 550 The memory property is measured by applying a constant voltage of 0.55 V to each EC element for 3 minutes, then leaving the element in an open circuit state, and measuring the change in optical density ΔOD after 1 hour.550 If the absolute value of (increase in transmittance) was less than 0.3, it was judged that there was a memory effect, and if it was 0.3 or more, it was judged that there was no memory effect.

[0067] [Table 2] [Explanation of symbols]

[0068] 2a, 2b: electrodes, 3a, 3b: electrochromic layers, 4: separator, 6: electrochromic element, 101: optical filter, 102: lens unit, 110: light receiving element, 100: imaging device

Claims

1. An electrochromic element comprising: a first electrode; a second electrode; a separator dividing the gap between the first electrode and the second electrode; a first electrochromic layer disposed between the first electrode and the separator and containing at least one cathode electrochromic compound; and a second electrochromic layer disposed between the second electrode and the separator and containing at least one anodic electrochromic compound, The separator is made of nanofibers, The ionic resistance in the thickness direction of the separator when impregnated with a 0.1 M tetrabutylammonium TFSI / propylene carbonate solution is 50 Ωcm. 2 More than 300Ωcm 2 An electrochromic element characterized by the following:

2. The electrochromic element according to claim 1, characterized in that the average fiber diameter of the separator is 10 nm or less.

3. The electrochromic element according to claim 1, characterized in that the nanofibers are made of nanocellulose.

4. The electrochromic element according to claim 1, characterized in that the separator has a curve ratio of 1.5 or more and 4.5 or less.

5. The electrochromic element according to claim 1, characterized in that the separator has a light transmittance of 80% or more at a wavelength of 550 nm.

6. An optical filter comprising an electrochromic element according to any one of claims 1 to 5, and a transistor connected to the electrochromic element.

7. A lens unit characterized by comprising an optical filter according to claim 6 and an imaging optical system having a plurality of lenses.

8. An imaging device characterized by comprising an optical filter according to claim 6 and a light-receiving element that receives light that has passed through the optical filter.

9. A window material characterized by comprising an electrochromic element according to any one of claims 1 to 5, and a transistor connected to the electrochromic element.

10. An electrochromic mirror characterized by comprising an electrochromic element according to any one of claims 1 to 5, and a reflective member disposed inside or outside the electrochromic element.

Images