Electrochromic element, and optical filter, lens unit, imaging device, window material, and electrochromic mirror having the same

Abstract

To inhibit an anode charge imbalance color from remaining without increasing power consumption and lowering the response speed in an EC element using a plurality of kinds of anode EC compounds of low-molecular organic compounds.SOLUTION: The normalized variable transmittance combined with absorption of a plurality of anodic electrochromic compounds is expressed as TA(λ), and the type and concentration of the anodic electrochromic compound are selected so that RGmax, which is the maximum value of the RGB ratio obtained from TA(λ) and the sensitivity of the photodetector and the ratio between a transmissive state of an electrochromic element and a colored state of the anodic electrochromic compound, is 1.37 or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an electrochromic element and an optical device having the electrochromic element. [Background technology]

[0002] Variable light transmittance elements, which electrically control the transmittance of light transmittance-reducing elements such as ND filters that reduce the light incident on photodetectors in imaging devices, offer greater flexibility in exposure adjustment and enable image expression that was previously impossible with elements with fixed transmittance. Several types of elements are used as variable light transmittance elements, but low-molecular-weight organic electrochromic elements (hereinafter, "electrochromic" may be abbreviated as "EC") are unique in that they combine high coloring / bleaching contrast with high maximum transmittance. These low-molecular-weight organic EC elements use low-molecular-weight organic EC compounds whose optical properties (absorption wavelength, absorbance) change through electrochemical redox reactions. When using low-molecular-weight organic EC compounds in optical devices, a challenge is to suppress the effects of changes in optical properties over time. Specifically, a challenge is to suppress the effects of color retention (color retention), which occurs when a portion of the low-molecular-weight organic EC compound remains colored even when voltage conditions are applied that would cause the EC element to bleach. One cause of this color retention is "charge imbalance," which occurs when oxygen that has invaded the EC element over time is reduced, disrupting the charge balance. Most of the color retention caused by charge imbalance over time, such as the reduction of invaded oxygen, is anodic charge imbalance color retention, in which the colored body of the anodic EC compound remains. Therefore, there is a need to suppress this anodic charge imbalance color retention. Patent Document 1 discloses the use of a non-EC material in an EC device that is more easily oxidized than the anodic EC compound. These materials are hereinafter referred to as "redox buffers." In EC devices, the oxidized form of the redox buffer is more stable than the oxidized form of the anodic EC compound, which is the colored form. Therefore, even if an anodic charge imbalance occurs during bleaching, the oxidized form of the corresponding redox buffer is generated rather than the colored form of the anodic EC compound remaining, within the range that can be covered by the charge of the redox buffer. Furthermore, because this redox buffer is non-EC, the generation of these oxidized or reduced forms has little effect on transmittance. As a result, even if a charge imbalance occurs, the EC device does not directly result in color retention. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 3798980 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the EC device of Patent Document 1, the redox buffer is more easily oxidized than the anodic EC compound and therefore more reactive in potential than the EC compound. Therefore, during the coloring operation of a typical EC device, the redox buffer reacts before the EC compound. As a result, compared to when a redox buffer is not used, unnecessary current flows that does not contribute to coloring, resulting in increased power consumption and a slower response speed. The object of the present invention is to suppress color retention due to anodic charge imbalance without increasing power consumption or reducing response speed in an EC element using multiple types of anodic EC compounds that are low-molecular-weight organic compounds. [Means for solving the problem]

[0005] A first aspect of the present invention is an electrochromic device comprising a first electrode, a second electrode, and an electrochromic layer disposed between the first electrode and the second electrode, wherein the electrochromic layer comprises a plurality of anodic electrochromic compounds which are low-molecular organic compounds, and a cathodic oxidation-reduction material, The electrochromic element is intended for a photodetector having a plurality of detection light wavelength regions, The normalized variable transmittance obtained by combining the absorptions of the plurality of anodic electrochromic compounds is expressed by the following formula: T A (λ), When the charge balance in the electrochromic layer is normal, Said T A The RGB signal ratio obtained from (λ) and the sensitivity of the photodetector is the ratio between when the electrochromic element is in a transmitting state and when the plurality of anodic electrochromic compounds are in a colored state, as shown below: G RI / G RT , G RT / G RI , G BI / G BT , G BT / G BI The maximum value of RG max is 1.37 or less.

number

[0006] According to the present invention, it is possible to provide an EC element that suppresses residual color due to anodic charge imbalance without using a redox buffer, thereby providing various optical devices with excellent transmittance control characteristics without increasing power consumption or reducing response speed. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram showing a schematic configuration of an example of an optical device using an EC element of the present invention. [Figure 2] 1 is a cross-sectional view schematically showing the configuration of an embodiment of an EC element of the present invention. [Figure 3] FIG. 1 is an explanatory diagram of the concept of charge balance / imbalance in an EC element. [Figure 4] FIG. 1 is a diagram showing an example of the spectral sensitivity of a photodetector targeted by an EC element. [Figure 5] FIG. 2 is a diagram illustrating an example of the spectrum of a light source of incident light. [Figure 6] FIG. 10 is a diagram showing the relationship between RGmax and a change in white balance gain. [Figure 7] FIG. 10 is a diagram illustrating the influence of incident light wavelength on changes in white balance gain. [Figure 8] FIG. 10 is a diagram showing the relationship between RΔOD and a change in white balance gain. [Figure 9] FIG. 1 is a diagram schematically illustrating a configuration of an embodiment of an optical filter. [Figure 10] FIG. 1 is a diagram schematically illustrating a configuration of an embodiment of an imaging device. [Figure 11] 1 is a diagram illustrating a configuration of an embodiment of a window material. [Figure 12] FIG. 1 shows the change molar extinction coefficient spectrum of the EC compound used in the examples. [Figure 13] FIG. 1 shows variable optical density spectra of anodic EC compounds of Examples and Comparative Examples. [Figure 14] FIG. 10 is a diagram showing the influence of the average ratio of ΔODA(λ) with wavelength width on the change in white balance gain. [Figure 15] FIG. 10 is a diagram showing the relationship between RW ΔOD and a change in white balance gain. DETAILED DESCRIPTION OF THE INVENTION

[0008] The electrochromic device of the present invention uses a plurality of anodic electrochromic compounds. In the first invention, the RG obtained based on the variable transmittance of the anodic electrochromic compounds and the sensitivity of the target photodetector is max The second and third aspects of the present invention are characterized by the fact that the ratio of the variable transmittance of the anodic electrochromic compound at a specific wavelength is defined as an index of the likelihood of color retention, thereby reducing color retention.

[0009] The electrochromic element of the present invention and an optical device using the element will be described in detail below with reference to the accompanying drawings. Note that the present invention is not limited to the following embodiments, and appropriate modifications and improvements to the following embodiments based on the ordinary knowledge of those skilled in the art are also included within the scope of the present invention, provided that they do not deviate from the spirit of the present invention.

[0010] FIG. 1 shows a schematic configuration of an example of an optical device using an electrochromic element (EC element) of the present invention. In FIG. 1, the optical device 10 includes an EC element 11 and a photodetector 12. Incident light 13 passes through the EC element 11, which has a controlled transmittance, thereby adjusting the amount of light incident on the photodetector 12. The incident light that passes through the EC element 11 enters the photodetector 12 and is converted into an electrical signal, which is then converted into information such as color and light intensity. The optical device 10 may also include a photographing optical system including multiple lenses and an aperture, an IR filter, and the like. In this case, the incident light that enters the optical device 10 passes through a photographing optical system (not shown) including multiple lenses and an aperture, then passes through the EC element 11 and an IR filter (not shown), and then enters the photodetector 12. The EC element 11 may also include a controller that controls its transmittance. In this case, the controller may function in conjunction with or be integrated with the controller (not shown) of the optical device 10. The optical device 10 may also include a temperature sensor, a recording device, and the like that acquire temperature information from the EC element, as needed. Each of the components shown in FIG. 1 will now be described in detail.

[0011] [EC element] The EC element 11 is a device that takes in light from the outside and passes the taken-in light through at least a part of an EC layer, thereby changing the characteristics of the emitted light, typically the light intensity, in a predetermined wavelength range relative to the incident light. 2 is a cross-sectional view in the thickness direction schematically showing the configuration of one embodiment of the EC element of the present invention. The EC element 11 of this embodiment has a first electrode 21, a second electrode 22, and an electrochromic layer (EC layer) 23 disposed between the first electrode 21 and the second electrode 22. The EC element 11 may also have substrates (a first substrate 26, a second substrate 27) and a sealing material 25. The EC element 11 in Fig. 2 is one example of the configuration of the EC element of the present invention, and the present invention is not limited to the configuration in Fig. 2. For example, an anti-reflection film layer may be provided between the substrate and the electrode, or between the electrode and the EC layer.

[0012] The EC element of the present invention has a maximum light attenuation ratio between the transmission state and the dimming state during normal use (the ratio of the amount of light emitted when the same amount of light is incident (transmission state / dimming state)) of preferably 8 (ND8) or more, and more preferably 32 (ND32) or more. There are two reasons for this: (a) Usefulness as an EC element: When the extinction ratio is 8 or less, the adjustable range of the EC element is limited, and the range of application as an EC element is severely limited. On the other hand, when the extinction ratio is 32 or more, the applicability as an EC element is dramatically expanded. (b) The greater the extinction ratio, the greater the maximum degree of charge imbalance color retention. For example, when the extinction ratio is small, such as 8 or less, the effect of color retention is relatively small. However, when the extinction ratio is 8 or more, the effect of color retention becomes significant, and when the extinction ratio is 32 or more, the effect becomes extremely significant. The present invention provides an EC element that suppresses anodic charge imbalance color retention, and to achieve this effect, an extinction ratio of 8 or more, preferably 32 or more, is preferable. Furthermore, "normal use" refers to conditions under which an EC element is normally used without any problems. For example, this does not refer to conditions under which the characteristics of an EC element would be rapidly deteriorated, but rather refers to values ​​listed in a specification sheet, etc.

[0013] The components of the EC element will be described below. <Substrate> In the case of an EC element 11 having substrates 26 and 27, as shown in FIG. 2, both substrates must be transparent if the EC element 11 is a transmissive type, and at least the substrates on the light-incident and light-exiting sides must be transparent if the EC element 11 is a reflective type. "Transparent" here refers to a light transmittance of 50% to 100%, more preferably 70% to 100%. Furthermore, "light" in this specification refers to light in the wavelength range for which the EC element is intended. For example, if the EC element is used as an optical filter for the visible light range, this refers to light in the visible light range, and if the EC element is used as an optical filter for the infrared range, this refers to light in the infrared range.

[0014] Specifically, colorless or colored glass or transparent resin can be used as the substrate. Examples of glass include optical glass, quartz glass, white plate glass, blue plate glass, borosilicate glass, alkali-free glass, and chemically strengthened glass. Examples of transparent resins include polyethylene terephthalate, polyethylene naphthalate, polynorbornene, polyamide, polysulfone, polyethersulfone, polyetheretherketone, polyphenylene sulfide, polycarbonate, polyimide, and polymethyl methacrylate. When a non-transparent substrate is used, there are no particular limitations.

[0015] <Electrode> The first and second electrodes are preferably made of a material that is stable in the operating environment of the EC device and that can rapidly undergo a redox reaction in response to the application of an external voltage. Examples of materials that can be used for the electrodes include transparent conductive materials and metals, which will be described later. At least one of the first electrode and the second electrode is preferably a transparent electrode. Here, "transparent" means that the light transmittance is 50% or more and 100% or less. By using a transparent electrode for at least one of the first electrode and the second electrode, light can be efficiently taken in from outside the EC element, and the light can interact with the EC compound in the EC layer, allowing the optical properties of the EC compound to be reflected in the emitted light.

[0016] The transparent electrode may be a film formed of a transparent conductive material on a substrate, a transparent electrode in which metal wires are partially arranged on a transparent substrate, etc. Here, although the metal wires themselves are not transparent, in the present invention, an electrode in which the metal wires are partially arranged and the light transmittance is set within the above range is called a transparent electrode. Examples of transparent conductive materials include transparent conductive oxides and carbon materials such as carbon nanotubes. Examples of transparent conductive oxides include tin-doped indium oxide (ITO), zinc oxide, gallium-doped zinc oxide (GZO), aluminum-doped zinc oxide (AZO), tin oxide, antimony-doped tin oxide (ATO), fluorine-doped tin oxide (FTO), and niobium-doped titanium oxide (TNO). Among these, ITO and FTO are preferred.

[0017] When an electrode is formed from a transparent conductive oxide, the thickness of the electrode is preferably 10 nm to 10 μm. In particular, by using ITO or FTO formed to a thickness in the range of 10 nm to 10 μm as an electrode, both high transparency and chemical stability can be achieved. When an electrode is formed using a transparent conductive oxide, the electrode may have a structure in which sublayers of transparent conductive oxide are stacked. This facilitates achieving high conductivity and high transparency. It is also preferable to make the electrode porous to increase the electrode area per projected area, thereby increasing the amount of redox substances and EC compounds immobilized on the electrode and enhancing the electrode reaction.

[0018] The metal constituting the electrode is not particularly limited, but electrochemically stable metals such as silver (Ag), gold (Au), platinum (Pt), and titanium (Ti) are preferably used. Furthermore, a grid-like arrangement pattern of metal wires is preferably used. Electrodes having metal wires are typically flat electrodes, but curved electrodes can also be used if necessary.

[0019] As described above, it is preferable that at least one of the first electrode and the second electrode is a transparent electrode. However, if one electrode is a transparent electrode, the other electrode can be selected according to the intended use of the EC device. For example, if the EC device is a transmissive EC device, it is preferable that both the first electrode and the second electrode are transparent electrodes. On the other hand, if the EC device is a reflective EC device, it is preferable that one of the first electrode and the second electrode is a transparent electrode, and the other is an electrode that reflects the light captured by the EC device. Furthermore, by forming a reflective layer or a scattering layer between the first electrode and the second electrode, the degree of freedom in the optical properties of the other electrode can be improved. For example, if a reflective layer or a scattering layer is introduced between the first electrode and the second electrode, an opaque electrode or an electrode that absorbs the target light can also be used as the other electrode.

[0020] The first electrode and the second electrode can be arranged in any commonly known manner for EC device electrode arrangements. A typical example is shown in FIG. 2 , in which a first electrode 21 formed on a first substrate 26 and a second electrode 22 formed on a second substrate 27 are arranged so that the first electrode 21 and the second electrode 22 face each other across an EC layer 23. In this case, the distance between the first electrode 21 and the second electrode 22 (inter-electrode distance) is preferably 1 μm or more and 500 μm or less. Increasing the inter-electrode distance allows for a thicker EC layer 23, allowing for a sufficient amount of EC compound to be disposed in the EC layer 23 for the EC device 11 to function effectively. This is advantageous in that it facilitates lowering the transmittance during coloring. On the other hand, reducing the inter-electrode distance is advantageous in that it facilitates increasing the response speed of the EC device 11. As described above, setting the inter-electrode distance to 1 μm or more and 500 μm or less facilitates achieving low transmittance and fast response during coloring.

[0021] <Sealing material> As shown in FIG. 2, the sealant 25 is disposed between the first electrode 21 and the second electrode 22, and bonds the first electrode 21 and the second electrode 22 together. The sealing material is preferably composed of a material that is chemically stable, impermeable to gases and liquids, and does not inhibit the redox reaction of the EC compound. For example, inorganic materials such as glass frit, organic materials such as epoxy and acrylic resins, and metals can be used. The sealing material may contain a spacer material to maintain the distance between the first electrode 21 and the second electrode 22. In this case, the first electrode 21, the second electrode 22, and the sealing material 25 can form a space for disposing the EC layer 23 between the electrodes.

[0022] If the sealing material 25 does not have the function of defining the distance between the first electrode 21 and the second electrode 22, a spacer having the function of defining and maintaining the distance between the two electrodes may be separately disposed to maintain the distance between the two electrodes. The spacer may be made of inorganic materials such as silica beads and glass fiber, or organic materials such as polyimide, polytetrafluoroethylene, polydivinylbenzene, fluororubber, and epoxy resin.

[0023] <Electrochromic layer> In the EC device of the present invention, the EC layer contains multiple types of anodic EC compounds and a cathodic redox material. The cathodic redox material is preferably an EC compound. The anodic EC compound and cathodic redox material of the EC layer may be dissolved in a solvent or immobilized on an electrode. Dissolving them in a solvent is preferable because the amount of the EC compound and redox material in the EC layer can be increased to enhance the contrast between coloring and fading. Immobilizing them is preferable because it can provide memory properties. The first and second electrodes may be porous electrodes integrated with the electrochromic layer.

[0024] (solvent) The solvent can be appropriately selected depending on the application, taking into consideration the solubility, vapor pressure, viscosity, potential window, etc. of the solutes, such as the anodic EC compound and the cathodic redox material, to be used. The solvent is preferably one that can dissolve the anodic EC compound and the cathodic redox material to be used. Furthermore, the solvent is preferably a polar solvent. Specific examples include organic polar solvents such as ether compounds, nitrile compounds, alcohol compounds, dimethyl sulfoxide, dimethoxyethane, sulfolane, dimethylformamide, dimethylacetamide, and methylpyrrolidinone, as well as water. Among these, solvents containing cyclic ethers, such as propylene carbonate, ethylene carbonate, γ-butyrolactone, valerolactone, and dioxolane, are preferred. These solvents containing cyclic ethers are preferred in terms of the solubility, boiling point, vapor pressure, viscosity, and potential window of the EC compound. Among cyclic ethers, solvents containing propylene carbonate and γ-butyrolactone are particularly preferred. Furthermore, ionic liquids can also be used as the solvent.

[0025] The solvent may further contain a polymer, gelling agent, or thickener to increase the viscosity of the EC layer or to form a gel. A polymer electrolyte or gel electrolyte may be used as the solvent or electrolyte. The polymer may be, but is not limited to, polyacrylonitrile, carboxymethyl cellulose, polyvinyl chloride, polyethylene oxide, polypropylene oxide, polyurethane, polyacrylate, polymethacrylate, polyamide, polyacrylamide, polyester, Nafion®, and derivatives thereof. Increasing the viscosity of the EC layer or forming a gel suppresses the migration of the EC compound within the EC layer. This further suppresses vertical color separation.

[0026] The EC layer may further contain a supporting electrolyte. The supporting electrolyte is not particularly limited as long as it is an ion-dissociating salt and has good solubility in the solvent. The supporting electrolyte is preferably a substance that is stable at the operating potential of the EC element. The supporting electrolyte may be selected from various cations and anions, and a combination of both may be used. Examples of cations include metal ions such as alkali metal ions and alkaline earth metal ions, and organic ions such as quaternary ammonium ions. Specifically, Li + , Na + , K. + , Ca 2+ , Ba 2+ Examples of anions include anions of various fluorine compounds, halide ions, etc. Specifically, ClO4 - , SCN - , BF4 - , AsF6 - , CF3SO3 - , CF3SO2NSO2CF3 - , PF6 - , I - , Br - , Cl - In addition, by using a salt compound as the EC compound, the EC compound may also function as a supporting electrolyte. Examples of EC compounds that are also salt compounds include viologen derivatives.

[0027] The method for forming the EC layer is not particularly limited, and examples thereof include a method of injecting a liquid containing a solvent and an EC compound into a gap provided between a first electrode and a second electrode by a vacuum injection method, an atmospheric injection method, a meniscus method, etc. Specifically, for example, into a cell formed by a pair of electrodes and a sealing material, a liquid containing a solvent and an EC compound is injected through an opening (not shown) formed in a part of the electrodes or the sealing material, and the opening is sealed with a sealing member.

[0028] (Redox substances and EC compounds) In the present invention, the EC layer disposed between the first electrode and the second electrode contains multiple types of anodic EC compounds and a cathodic redox material. The cathodic redox material is preferably an EC compound. The first electrode and the second electrode may be porous electrodes integral with the electrochromic layer.

[0029] In the present invention, at least two types of redox substances (including a low-molecular-weight organic EC compound) are present between the first electrode and the second electrode. Specifically, the two types of redox substances present between the first electrode and the second electrode are either of the combinations shown in (i) or (ii) below, with the preferred configuration being (ii), which can increase the coloring / bleaching contrast. The anodic EC compound is a low-molecular-weight organic compound in either case. (i) Anodic EC compounds and cathodic redox materials (ii) Anodic EC compounds and cathodic EC compounds

[0030] In the present invention, the color retention caused by charge imbalance in a so-called complementary EC element that uses an anodic EC compound and a cathodic redox material is suppressed. The concept of charge balance / imbalance will be described later.

[0031] As used herein, a redox substance refers to a compound that can be repeatedly oxidized and reduced within a predetermined potential range, and inorganic or organic substances can be used without particular limitations. Among these, low-molecular-weight organic EC compounds are preferred due to their compatibility with the operating environment. In this specification, redox substances may be referred to as anodic or cathodic redox substances. An anodic redox substance is a substance that is typically in a reduced state when no driving voltage is applied to the device and becomes oxidized when a driving voltage is applied to the device. A cathodic redox substance is a substance that is typically in an oxidized state when no driving voltage is applied to the device and becomes reduced when a driving voltage is applied to the device.

[0032] As used herein, the term "EC compound" refers to a type of redox substance, a compound whose optical properties change in the target light wavelength range of the EC element due to a redox reaction. Examples of optical properties include light absorption properties and light reflection properties, and are typically light absorption properties. EC compounds can also be said to be compounds whose light transmittance changes in the target light wavelength range of the EC element due to a redox reaction. The phrase "changes in optical properties" here typically refers to switching between a light absorbing state and a light transmitting state. In this case, the EC compound can also be said to be a compound whose light absorbing state and a light transmitting state change due to a redox reaction.

[0033] As used herein, the term "anodic EC compound" refers to an EC compound whose optical properties change in the target wavelength region of the EC device due to an oxidation reaction when the EC device is operated. An oxidation reaction typically involves the removal of electrons from the EC compound. Furthermore, as used herein, the term "cathodic EC compound" refers to an EC compound whose optical properties change in the target wavelength region of the EC device due to a reduction reaction when the EC device is operated. A reduction reaction typically involves the addition of electrons to the EC compound. Typical examples of anodic EC compounds include compounds that change from a light-transmitting state to a light-absorbing state due to an oxidation reaction when the EC device is operated. Typical examples of cathodic EC compounds include compounds that change from a light-transmitting state to a light-absorbing state due to a reduction reaction when the EC device is operated. However, the term is not limited to these examples and may also refer to compounds that change from a light-absorbing state to a light-transmitting state due to an oxidation reaction or a reduction reaction when the EC device is operated. In the following description, in order to easily visualize the change in the light absorption properties of an EC compound, a typical example will be taken, in which an EC element changes from a light-transmitting state (bleached state) to a light-absorbing state (colored state) when driven.

[0034] Both the anodic and cathodic EC compounds undergo oxidation or reduction reactions by controlling the voltage applied between the first and second electrodes or by switching the EC device on and off, thereby taking on at least two distinct states. In this specification, the EC compound in its oxidized state through one or more oxidation reactions is referred to as its "oxidized form," and the EC compound in its reduced state through one or more reduction reactions is referred to as its "reduced form." That is, the anodic EC compound is in its reduced form when the EC device is not activated, but partially becomes its oxidized form when the EC device is activated. Similarly, the cathodic EC compound is in its oxidized form when the EC device is not activated, but partially becomes its reduced form when the EC device is activated.

[0035] Some literature describes the state of an EC compound as changing from an oxidant to a neutral state and then to a reduced state (or vice versa). However, in the following explanation, we will use the terms oxidant and reduced state, recognizing that a reduced state is essentially the state produced when an oxidant is reduced, and an oxidant is essentially the state produced when a reduced state is oxidized. For example, ferrocene (a neutral molecule as a whole) containing divalent iron is the reduced state of ferrocene (the anodic redox material) when ferrocene functions as an anodic redox material. When this reduced state is oxidized to a trivalent iron state (ferrocenium ion), it is the oxidized state of ferrocene (the anodic redox material), specifically the first oxidized state. Furthermore, when a dicationic salt of a viologen functions as a cathodic EC compound, the dicationic salt is the oxidized state of the cathodic EC compound. Furthermore, a monocationic salt obtained by one-electron reduction of the dicationic salt is the reduced state of the cathodic EC compound, specifically the first reduced state.

[0036] The EC compound used in the present invention is a low-molecular-weight organic compound having a molecular weight of 2000 or less. The molecular weight here means a molecular weight of 2000 or less excluding counter ions. Preferably, both the anodic EC compound and the cathodic EC compound are compounds that change from a decolorized form to a colored form upon activation of the EC device. The EC compound may contain multiple types of anodic EC compounds or multiple types of cathodic EC compounds.

[0037] Examples of anodic EC compounds include aromatic amine compounds, with dihydrophenazine derivatives being particularly preferred. Dihydrophenazine derivatives exhibit high durability in accelerated driving tests. In their neutral (reduced) state, these compounds have an absorption peak in the ultraviolet range, no absorption in the visible range, and a bleached state with high transmittance in the visible range. When these molecules undergo an oxidation reaction to form radical cations (oxidized forms), the absorption peak shifts to the visible range, resulting in a colored state. The absorption wavelength of these molecules can be altered to some extent by expanding or contracting their π-conjugation length or by modifying the substituents to alter the π-conjugated system. Generally, phenazine derivatives have an absorption peak around 500 nm in the colored state and exhibit a yellow to red color. Over time, anodic charge imbalance results in the color of the anodic EC compound, i.e., the yellow to red color of the dihydrophenazine derivative, remaining in the bleached state. Since the absorption wavelength range of the colored product of one type of dihydrophenazine derivative is not wide, it is preferable to use multiple types of compounds for applications that require absorption over a wide wavelength range, such as ND filters, which can improve color reproducibility when used as an ND filter, for example.

[0038] The cathodic EC compound is not particularly limited, but examples thereof include pyridine derivatives such as viologen derivatives, quinone compounds, etc. Among these, pyridine derivatives such as viologen derivatives are most preferably used. Therefore, the cathodic EC compound is preferably a compound having a pyridine skeleton or a quinone skeleton, and more preferably a compound represented by the following general formula (1).

[0039] [ka]

[0040] In the general formula (1), X1 and X2 are each independently selected from an alkyl group, an aralkyl group, and an aryl group. The alkyl group, the aralkyl group, and the aryl group may have a substituent. R 11 ~R 18 are each independently any one of a hydrogen atom, an alkyl group, an aralkyl group, an alkoxy group, an aryl group, a heterocyclic group, a substituted amino group, a halogen atom, and an acyl group. The alkyl group, the alkoxy group, the aralkyl group, the aryl group, and the heterocyclic group may have a substituent and may have a cyclic structure. - and A2 - each independently represents a monovalent anion.

[0041] <Charge balance / imbalance> The concept of charge balance / imbalance will be explained below with reference to the drawings. FIG. 3 is a diagram for explaining the concept of charge balance / imbalance. Note that FIG. 3 is a complementary EC element, and is directed to a system in which an anodic EC compound and a cathodic EC compound are used in combination. FIG. 3 shows a first electrode E1, which is an anode, and a second electrode E2, which is a cathode. In FIG. 3, A is the reduced form (discolored state) of the anodic EC compound, and A + In FIG. 3, C is the oxidized form (colored state) of the anodic EC compound. Furthermore, in FIG. 3, C is the oxidized form (discolored state) of the cathodic EC compound, and C - is the reduced form (colored state) of the cathodic EC compound.

[0042] 3(a) shows the coloring process of an EC device. When a coloring voltage is applied between the first electrode E1 and the second electrode E2, an oxidation reaction of the anodic EC compound shown in (α) below proceeds at the first electrode E1, and a reduction reaction of the cathodic EC compound shown in (β) below proceeds at the second electrode E2. A → A + +e - (α) C+e - →C - (β)

[0043] As these reactions proceed, the EC layer becomes colored.

[0044] Figure 3(b) shows the decoloring process, which is the opposite process to the coloring process. To decolorize the EC layer, a decoloring voltage (e.g., short circuit (0 V)) is applied between the first electrode E1 and the second electrode E2, causing the reverse reaction of the reaction shown in Figure 3(a) to proceed, as indicated by the arc-shaped arrow in Figure 3(b). This allows the colored EC compound to return to its decolored state. When the reactions shown in Figures 3(a) and (b) are repeated, the charge balance of the EC element is normal, and the element normally repeats coloring and fading.

[0045] On the other hand, when an EC element is operated, a process other than this normal coloring / decoloring may occur in some part of the element, causing the charge balance to be disrupted. There are several reasons for this, but here we will take the degradation of the reduced form of the cathodic EC compound as an example and explain it using Figure 3(c). (The irreversible reduction reaction of oxygen that has entered the EC element is also a similar process.) The reduced form C of the cathodic EC compound that has been colored through the normal coloring process - When the second electrode E2 is degraded and is no longer able to react, or when an irreversible reduction reaction of oxygen that has entered the EC element occurs, the oxidized form A of the anodic EC compound is also produced at the first electrode E1. +However, the anodic EC compound loses its electron supply source and is no longer able to react. In the following explanation, this phenomenon is referred to as a charge imbalance. As a result of the charge imbalance, the EC element exhibits a color loss problem in which a colored body of the anodic EC compound remains, even though the anodic EC compound is normal.

[0046] Charge imbalance can occur due to irreversible electron transfer reactions (particularly electrode reactions) of the substrates involved in the redox reaction. Specifically, this can be due to impurities (derived from the EC compound, environmental impurities (oxygen, water, etc.), or sealants) or chemical reactions between radicals. A typical example is the irreversible reduction of oxygen that has entered the EC element. This can result in poor decolorization, with the color of the anodic EC compound remaining.

[0047] <Photodetector> The first EC element of the present invention is intended for a specific photodetector. In other words, this EC element is designed to function in combination with a specific photodetector. Examples include a combination of a camera system (camera, interchangeable lens) and an imaging element such as a CMOS sensor, a combination of a variable transmittance window and a human eye, a combination of variable transmittance glasses and a human eye, and a combination of a variable reflectance mirror and a human eye. This photodetector has multiple detection light wavelength ranges. Specifically, in the case of an imaging CMOS sensor, it has multiple detection light wavelength ranges of R, G, and B, and in the case of a human eye, it has multiple detection light wavelength ranges of the x bar, y bar, and z bar of the CIE color matching functions, as an example.

[0048] The detectable wavelength range of a photodetector is the wavelength range in which the photodetector has significant spectral sensitivity. The spectral sensitivity of a photodetector is the spectral sensitivity when used in its normal configuration. Specifically, when the photodetector is used as part of a camera system, it is the spectral sensitivity including other optical elements normally used in the camera system, such as UV and IR cut filters and low-pass filters.

[0049] Figure 4(a) shows an example of the spectral sensitivity of an RGB image sensor, including the effects of the transmittance of UV and IR cut filters and low-pass filters when the photodetector is used as a camera system. If the photodetector is the human eye, the CIE color matching functions correspond to this. Figure 4(b) shows the CIE color-matching functions. A typical example of the detection wavelength range of these photodetectors is the range from 425 nm to 680 nm. Another example is the wavelength range where the photodetector has a sensitivity of 10% or more of the maximum spectral sensitivity.

[0050] <Incoming light> The light incident on the EC element (light incident on the photodetector through the EC element) will now be described. The EC element of the present invention is an EC element that suppresses color retention due to anodic charge imbalance. As the light source of the reference incident light, natural daylight, which is frequently used for EC elements, is preferably selected, and a light source corresponding to this is preferably selected. Figure 5 shows examples of the spectra of natural daylight and simulated sunlight with a color temperature of approximately 5000 K. Examples of defined light sources include CIE D65, D55, D50, illuminant B, and illuminant C.

[0051] <Principle of anodic charge imbalance to prevent color retention> The spectra of complementary EC devices are generally designed as follows: The absorption spectrum of a characteristic anodic EC compound is complementarily combined with the absorption spectrum of a cathodic EC compound that absorbs at a different wavelength than the anodic EC compound. This achieves a colored absorption spectrum with low wavelength dependency (high neutral density) for the entire EC device. The colored anodic EC compounds, which are low-molecular-weight organic compounds used in such EC devices, often have relatively sharp absorption spectra. For example, dihydrophenazine derivatives, a typical anodic EC compound, have an absorption peak around 500 nm in the colored state and exhibit a yellow to red color in the colored state. Over time, when an EC device experiences an anodic charge imbalance, the color of the anodic EC compound remains in the bleached state, resulting in a residual color.

[0052] In response to this, the inventors have devised a method to suppress the occurrence of residual color even when a charge imbalance occurs by combining the absorption spectra of the individual colored bodies of multiple anodic EC compounds (the absorption spectrum of the colored bodies of multiple anodic EC compounds) and making it closer to achromatic (regardless of the absorption spectrum of the cathodic EC compound).To achieve this, an index RG max We developed RG max The invention was completed by identifying the effective range for suppressing anodic charge imbalance color retention using this index, making it possible to derive the spectral conditions for the colored state of the anodic EC compound, and then selecting the type and concentration of the anodic EC compound based on this. max The conditions for this will be described in detail below.

[0053] <RG max > In the optical device 10 shown in FIG. 1, the photodetector 12 has an effective wavelength range of λ0 to λ1 and a spectral sensitivity of D R (λ),D G (λ),D B(λ) of the RGB image sensor, and the signal strength output in response to the light incident on the image sensor is S R ,S G ,S B Here, R stands for red, G stands for green, and B stands for blue. The transmittance of the EC element in the transmission state is T0(λ). The effective maximum variable optical density of the EC element (the maximum variable optical density during normal operation of the EC element, the absorption by the anodic EC compound + cathodic EC compound) is ΔOD max and the average variable optical density in the effective wavelength range of the photodetector is B. ΔOD max The normalized variable optical density (absorption by the anodic EC compound and the cathodic EC compound, average optical density = 1) was calculated by the average variable optical density B. ave Then, the normalized variable optical density ΔOD ave The contribution of each colored body of the anodic EC compound and the cathodic EC compound in Aave , ΔOD Cave (ΔOD ave =ΔOD Aave +ΔOD Cave ) The normalized variable transmittance T of the anodic and cathodic EC compounds, respectively A (λ), T C (λ) is given by the following formula:

[0054]

number

[0055] The RGB signal intensity of the image sensor when the charge balance is normal is given by the following formula using the incident light spectrum I0(λ):

[0056]

number

[0057] In contrast, the charge imbalance causes the normalized variable transmittance T A RGB signal of the image sensor when the colored body of the anodic EC compound corresponding to (λ) remains Strength S RI ,S GI ,S BI is given by the following formula:

[0058]

number

[0059] At this time, let us consider the correction ratio of the R and B signals for each wavelength range of the detected light from the photodetector in the transmitted state, with G of RGB as the reference. The signal ratio G when the charge balance is normal RT ,G BT , signal ratio at charge imbalance G RI ,G BI are written as gains (reciprocals) based on G as shown in the following equations. G RT =S GT / S RT G BT =S GT / S BT G RI =S GI / S RI G BI =S GI / S BI

[0060] The RG used as the degree of change in these signal correction ratios R , R.G. B As shown in the formula below, G R ,G B is given by the ratio of RG R =G RI / G RT RG B =G BI / G BT

[0061] And, RG is an index of how easily color retention occurs when a charge imbalance occurs. max is the above RG R ,RG B and its reciprocal (1 / RG R , 1 / RG B ) four values, namely, G RI / G RT , G RT / G RI , G BI / G BT , G BT / G BI is the maximum value among

[0062] That is, RG max is the normalized variable transmittance T A It is the maximum value of the ratio of the RGB signal ratio obtained from (λ) and the sensitivity of the photodetector when the EC element is in a transmitting state to when the anodic EC compound is in a colored state.

[0063] This RG maxThe effect of charge imbalance on the likelihood of color retention is evaluated using the change in white balance gain (ΔWBG). Here, ΔWBG is expressed as the ratio of the white balance gain when there is a charge imbalance (normal balance / imbalance, or imbalance / normal balance, whichever is larger) to the white balance gain of the RGB signals acquired by the image sensor when the charge balance is normal.

[0064] In Figure 6, ΔWBG is the vertical axis and RG max The horizontal axis shows the relationship between ΔWBG and RG. max The simulation was performed under the following conditions: The normalized variable optical density spectrum was obtained by arbitrarily combining the spectra from the following two groups so that the sum of the proportions of the respective components was 1. (I) The normalized variable optical density (ΔOD Aave or ΔOD Cave ) spectrum. (II) A flat (wavelength-independent) variable optical density spectrum. The average variable optical density B of the effective wavelength region of the photodetector was 0.5, the light source was natural daylight shown in Figure 5, and the photodetector spectral sensitivity was the spectral sensitivity of the image sensor shown in Figure 4(a).

[0065] [ka]

[0066] From here RG max It was confirmed that ΔWBG, an index of remaining charge imbalance color, increased with increasing RG. max However, it can be confirmed that this effectively functions as an indicator of the likelihood of color retention when a charge imbalance occurs. When the EC element of the present invention is used as a light intensity adjustment means (ND filter) in the visible light region, the white balance gain change is preferably in the range of 5% or less. When used as a more advanced light intensity adjustment means, the white balance gain change is preferably in the range of 3% or less. These values ​​were evaluated by sensory evaluation as being at a level where a clear color change (color retention) of the device is hardly noticeable in the former range, and at a level where a color change (color retention) of the device is hardly noticeable in the latter range.

[0067] From Figure 6, the preferred RG max The range is the RG range where the white balance gain change is less than 5%. max is in the range of 1.37 or less, and more preferably, the white balance gain change is in the range of 3% or less. max The preferred RG according to the present invention is 1.21 or less. max By selecting the type and concentration of the anodic EC compound so as to provide the above, it is possible to provide an EC element in which the anodic charge imbalance color retention is suppressed.

[0068] The reason why the EC element of the present invention uses multiple anodic EC compounds is that the absorption wavelength range of colored bodies of anodic low-molecular-weight organic EC compounds is generally limited to a narrow range. When applied to ND filters, etc., using multiple types of EC compounds and overlapping their absorption wavelength ranges can prevent bias in color (absorption wavelength). It is preferable to use three or more types of EC compounds in combination. The reason for this is described below.

[0069] (a) When forming a variable transmittance spectrum by combining EC compounds with different variable absorption spectra, the more types of EC compounds there are, the more detailed the absorption wavelengths can be complemented. As a result, it is possible to achieve higher color reproducibility and suppress color retention when charge imbalance occurs. Specifically, this can be explained as follows: In terms of concentration ratio, when there are two types of EC compounds, once the concentration ratio of one EC compound is determined, there is no flexibility in the concentration ratio of the other EC compounds. When there are three or more types of EC compounds, even if the concentration ratio of one EC compound is determined, there is flexibility in the concentration ratio of the other two EC compounds, making it possible to complement more detailed absorption wavelengths.

[0070] (b) The photodetectors targeted by ND filters have three or more detection wavelength ranges, such as the human eye and RGB sensors. Therefore, if there are three or more types of EC compounds, the degree of light absorption corresponding to each detection wavelength range can be adjusted relatively freely relative to other EC compounds, which dramatically increases the effectiveness of the present invention in suppressing color retention when a charge imbalance occurs.

[0071] From the above viewpoint, it is preferable that at least one of the EC compounds selected from the plurality of anodic EC compounds has a peak of a variable absorption spectrum in each of the plurality of detection light wavelength ranges of the photodetector. This allows for more flexibility in setting the optical absorption corresponding to the detection light wavelength range of the photodetector with respect to other EC compounds. In this case, each of the plurality of detection light wavelength ranges of the photodetector is the wavelength range of the detection light wavelength range that is maximum in the normalized sensitivity spectrum of the photodetector. 4(b), for example, the multiple detection light wavelength regions (x bar, y bar, z bar) are x bar: 580 nm to 680 nm, y bar: 500 nm to 580 nm, and z bar: 425 nm to 500 nm. Preferably, at least one compound selected from the multiple anodic EC compounds has a peak of a variable absorption spectrum in each of these regions.

[0072] Next, the index RG, which is the likelihood of color retention when the aforementioned charge imbalance occurs, is max In addition, for the purpose of making the present invention easier to understand and apply, the variable optical density (ΔOD A The ratio of (λ) at a specific wavelength is presented as an index. In order to select an effective wavelength as this specific wavelength, we investigated the wavelength dependency of the likelihood of color retention.

[0073] Figure 7 shows the effect of the incident light wavelength (horizontal axis) on the white balance gain change (vertical axis). Specifically, it simulates the change in white balance gain when the transmittance at a certain wavelength of the EC element is halved. The conditions used here were the daytime natural light shown in Figure 5 as the light source, the spectral sensitivity of the image sensor shown in Figure 4(a) as the photodetector spectral sensitivity, and the same EC compound spectrum as that used in the simulation shown in Figure 6. From this, it can be seen that wavelengths of 510 nm and 605 nm have the greatest effect on the R gain change, and wavelengths of 460 nm and 550 nm have the greatest effect on the B gain change. From this, it can be seen that the ratio of the variable optical density (R ΔOD ) was used as an index. ΔOD The effect of charge imbalance on the likelihood of color retention is evaluated using the white balance gain change (ΔWBG).

[0074] In Fig. 8, ΔWBG is the vertical axis and R ΔOD The horizontal axis shows the relationship between ΔWBG and R ΔOD is the aforementioned RG max The simulation was carried out under the same conditions as in the previous section. ΔOD It was confirmed that ΔWBG, an index of remaining charge imbalance color, increased with increasing R ΔOD It can be confirmed that this effectively functions as an indicator of the likelihood of color retention when a charge imbalance occurs. A (460nm) and ΔOD AThe maximum value of the ratio of (550nm) is "605nm / 510nm" A (605 nm) and ΔOD A (510 nm) means the maximum value of the ratio.

[0075] When the EC element of the present invention is used as a light intensity adjustment means (ND filter) in the visible light region, the white balance gain change is preferably in the range of 5% or less as described above. When used as a more advanced light intensity adjustment means, the change is preferably in the range of 3% or less. From Figure 8, the preferred R ΔOD The range is the range where the white balance gain change is 5% or less. A (460nm) and ΔOD A (550nm) ratio is 1.90 or less, and ΔOD A (605 nm) and ΔOD A The maximum value of the ratio of (510 nm) is 1.72 or less. A more preferable range is a range in which the white balance gain change is 3% or less. A (460nm) and ΔOD A (550nm) ratio is 1.44 or less, and ΔOD A (605 nm) and ΔOD A The maximum value of the ratio of (510 nm) is 1.41 or less. A (λ n ) and ΔOD A (λ m ) and the maximum value of the ratio is ΔOD A (λ n ) / ΔOD A (λ m ), or ΔOD A (λ m ) / ΔOD A (λ n ) whichever is larger. According to the present invention, a suitable R ΔOD By selecting the type and concentration ratio of the anodic EC compound so as to provide the above, it is possible to provide an EC element in which the anodic charge imbalance color retention is suppressed.

[0076] The low molecular weight organic EC compound preferably used in the present invention has an absorption spectrum as shown in FIG. 12. As shown, the spectrum of an EC compound shows an absorbance peak at a specific wavelength, and has a range of absorbance in the wavelength direction centered on that peak. On the other hand, the spectral sensitivity of the photodetector that the EC element of the present invention targets also shows a sensitivity peak at a specific wavelength, and has a sensitivity range in the wavelength direction centered on that peak, as shown in FIG. 4. Therefore, the wavelength-dependent profile of the white balance gain change also has a range in the wavelength direction. From this, it is possible to reduce the ΔOD A We considered evaluating the wavelength range in which the ratio of ΔOD is calculated over a certain range. When this range is small, the stability of the effect may be somewhat reduced for EC compounds with narrow, sharp absorption spectra. (Depending on whether or not the selected wavelength matches, the effect may appear stronger or weaker than it actually is.) On the other hand, when this range is large, the effect on white balance gain changes becomes weaker, and there is a strong tendency for its effectiveness as an evaluation index to decrease. (The specificity for RGB signals decreases.) For this reason, it is important to consider the ΔOD A We investigated the appropriate value for the width of the wavelength range for calculating the ratio.

[0077] Figure 14 shows the ΔOD A (460nm) and ΔOD A (550nm) ratio, also known as ΔOD A (605 nm) and ΔOD A This shows the effect on the white balance gain change when a wavelength range is given when calculating the ratio (460, 550, 605, 510 nm). Specifically, a wavelength range with a range in the wavelength direction is set around each wavelength (460, 550, 605, 510 nm) for which the ratio is calculated, and the ΔOD in that wavelength range is calculated. A The average value of ΔOD in that wavelength region A Use as the value of ΔOD AThe ratio of was calculated. Other conditions were the same as those in Figure 8. The horizontal axis of Figure 14 is the total width (unit: nm) in the wavelength direction of the wavelength region, and the vertical axis shows the influence on the white balance gain change, normalized so that when the width is zero (one point), it is 1. From this, it can be seen that by using a total width up to 30 nm, the influence on the white balance gain change is small, and the difference in influence depending on the type of white balance gain (B gain, R gain) is also small. From this, it can be seen that the ΔOD A The width of the wavelength region for calculating the ratio was set to 30 nm in total.

[0078] From this, for each of the R gain and B gain, the average variable optical density ΔOD in the full 30 nm range centered on the wavelength with the greatest effect is calculated. A The ratio (R WΔOD ) was used as an index. WΔOD The effect of charge imbalance on the likelihood of color retention is evaluated using the white balance gain change (ΔWBG).

[0079] In Fig. 15, ΔWBG is the vertical axis and R WΔOD The horizontal axis shows the relationship between ΔWBG and R WΔOD is the same as the R ΔOD The simulation was carried out under the same conditions as in the previous section. WΔOD It was confirmed that ΔWBG, an index of remaining charge imbalance color, increased with increasing R WΔOD It can be confirmed that this effectively functions as an index of the likelihood of color retention when a charge imbalance occurs. A and ΔOD in the wavelength range of 535nm to 565nm A Similarly, "605nm / 510nm" means the maximum value of the ΔOD in the wavelength range of 590nm to 620nm. A and ΔOD in the wavelength range of 495nm to 525nm A This means the maximum ratio of the average of ΔODA By setting the width of the wavelength region for calculating the ratio to 30 nm, it is possible to stably evaluate the influence of changes in white balance gain even for EC compounds with narrow and sharp absorption spectra. Furthermore, it can be used as an effective evaluation index without reducing the specificity for RGB signals. In the following explanation, "λ" is used. p ~λ q ΔOD in the wavelength region A "Average of ΔOD A (λ p ~λ q (average)"

[0080] When the EC element of the present invention is used as a light amount adjusting means (ND filter) in the visible light region, the white balance gain change is preferably in the range of 5% or less as described above. When used as a more advanced light amount adjusting means, it is preferably in the range of 3% or less. From FIG. 15, it is clear that the preferable R WΔOD The range is the range where the white balance gain change is 5% or less. A (average 445nm~475nm) and ΔOD A (535nm~565nm average) maximum ratio is 1.90 or less, and ΔOD A (590nm~620nm average) and ΔOD A The maximum value of the ratio to the average of 495 nm to 525 nm is 1.65 or less. A more preferable range is a range in which the white balance gain change is 3% or less. A (average 445nm~475nm) and ΔOD A (535nm~565nm average) the maximum ratio is 1.45 or less, and ΔOD A (590nm~620nm average) and ΔOD A (average of 495 nm to 525 nm) is 1.37 or less. A (λ p ~λ q average) and ΔOD A (λ r ~λ s The maximum ratio of ΔOD A (λ p ~λq average) / ΔOD A (λ r ~λ s average), or ΔOD A (λ r ~λ s average) / ΔOD A (λ p ~λ q According to the present invention, the preferred R WΔOD By selecting the type and concentration ratio of the anodic EC compound so as to provide the above, it is possible to provide an EC element that suppresses the anodic charge imbalance color retention.

[0081] <Effects of the present invention> In the EC device of the present invention, the colored state of the multiple anodic EC compounds is made closer to achromatic color, thereby suppressing the occurrence of color residue even when a charge imbalance occurs. Specifically, in the first invention, the RG (Rhodogram) described using the relationship between the spectrum and spectral sensitivity of the colored body of the anodic EC compound is used as an index of the likelihood of color residue when a charge imbalance occurs. max By selecting the type and concentration of the anodic EC compound so that this index falls within a specified range, color retention due to anodic charge imbalance can be suppressed.

[0082] In the second invention, the R ΔOD By selecting the type and concentration of the anodic EC compound so that this index falls within a specified range, color retention due to anodic charge imbalance can be suppressed.

[0083] In addition, in the third invention, as an index of the likelihood of color retention when a charge imbalance occurs, R is described using the average ratio of a specific wavelength region of the variable optical density spectrum of the colored body of the anodic EC compound. WΔOD By selecting the type and concentration of the anodic EC compound so that this index falls within a specified range, color retention due to anodic charge imbalance can be suppressed.

[0084] This suppresses the effects of changes in the optical properties of the EC element over time, thereby extending the usable time of the EC element. Other methods for extending the usable time of an EC element include the development of highly durable materials, improvements to the element configuration (including improved sealing materials), and improvements to the driving method. While the method of the present invention is different from these methods, it can be easily combined with the previously mentioned methods. This effectively extends the usable time of the EC element even further.

[0085] [Optical device] The EC device of the present invention can be used in optical devices such as optical filters, lens units, imaging devices, window materials, and electrochromic mirrors.

[0086] <Optical filters> A first embodiment of the optical filter of the present invention comprises an EC element of 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. Examples of the active element include a transistor. The transistor may have an oxide semiconductor such as InGaZnO in its active region.

[0087] A second embodiment of the optical filter of the present invention includes an EC element of the present invention and a driver connected to the EC element. Figure 9 is a diagram showing a schematic configuration of an optical filter including an EC element 11 and a driver 30 that drives the EC element 11. The driver 30 for the EC element 11 of this embodiment includes a drive power supply 32, a resistor switch 33, and a controller 31. The driving power supply 32 applies to the EC element 11 a voltage necessary to cause an electrochemical reaction in the EC material contained in the EC layer of the EC element 11. A constant driving voltage is preferable. This is because, when the EC material is composed of multiple types of materials, the absorption spectrum may change due to differences in the redox potentials and molar absorption coefficients of the materials. The driving power supply 32 starts applying voltage or maintains the applied state in response to a signal from the controller 31. The constant voltage is maintained during the period in which the light transmittance of the EC element 11 is controlled.

[0088] The controller 31 controls the transmittance of the EC element 11 in a manner appropriate for the EC element 11 being used. Specifically, this can involve inputting predefined conditions into the EC element 11 for a desired transmittance setting, or comparing the transmittance setting with the transmittance of the EC element 11 and selecting and inputting conditions that match the setting. Parameters that can be varied include voltage, current, and duty ratio. The controller 31 can change the color density of the EC element by varying the voltage, current, or duty ratio.

[0089] 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 33 switches between a resistor R1 (not shown) and a resistor R2 (larger than R1) and connects them in series in a closed circuit including the drive power supply 32 and the EC element 11. The resistance value of resistor R1 is preferably smaller than the largest impedance of the closed circuit, and is preferably 10 Ω or less. The resistance value of resistor R2 is preferably larger than the largest impedance of the closed circuit, and is preferably 1 MΩ or more. Resistor R2 may be air. In this case, strictly speaking, the closed circuit becomes an open circuit, but it can be considered a closed circuit by regarding the air as resistor R2. The controller 31 sends a switching signal to the resistor switch 33 to control the switching of the resistors R1 and R2. The controller 31 may generate a PWM signal using a comparator or the like without using the resistor switch 33.

[0090] <Lens unit> The lens unit of the present invention includes an imaging optical system having a plurality of lenses and the optical filter of the present invention. The optical filter may be provided either between the plurality of lenses or outside the lenses. The optical filter is preferably provided on the optical axis of the lenses.

[0091] <Imaging device> The imaging device of the present invention includes the optical filter of the present invention described above 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 configured such that a main body having a light-receiving element and a lens unit having a lens can be separated. If the imaging device can be separated into a main body and a lens unit, the present invention also includes a configuration in which an optical filter separate from the imaging device is used during imaging. In such cases, the optical filter may be located outside the lens unit, between the lens unit and the light-receiving element, or between multiple lenses (if the lens unit has multiple lenses).

[0092] FIG. 10(a) is a schematic diagram of an example of an imaging device in which an optical filter is arranged in a lens unit, and FIG. 10(b) is a schematic diagram of an example of an imaging device in which an optical filter is arranged in an imaging unit. 10 includes a lens unit 42 and an imaging unit 43. The lens unit 42 includes an optical filter 41 and an imaging optical system including a plurality of lenses or a lens group. The optical filter 41 is the optical filter of the present invention described above.

[0093] 10(a), the lens unit 42 represents, for example, a rear-focusing zoom lens in which focusing is performed after the aperture. It has four lens groups, in order from the object side: a first lens group 44 with positive refractive power, a second lens group 45 with negative refractive power, a third lens group 46 with positive refractive power, and a fourth lens group 47 with positive refractive power. Magnification is changed by changing the distance between the second lens group 45 and the third lens group 46, and focusing is performed by moving some of the lens groups in the fourth lens group 47.

[0094] The lens unit 42 has, for example, an aperture diaphragm 48 between the second lens group 45 and the third lens group 46, and an optical filter 41 between the third lens group 46 and the fourth lens group 47. The lens unit is arranged so that light passing through each of the lens groups 44 to 47, the aperture diaphragm 48, and the optical filter 41, and the amount of light can be adjusted using the aperture diaphragm 48 and the optical filter 41. The lens unit 42 is detachably connected to the imaging unit 43 via a mount member (not shown).

[0095] In this embodiment, the optical filter 41 is disposed between the third lens group 46 and the fourth lens group 47 in the lens unit 42, but the imaging device is not limited to this configuration. For example, the optical filter 41 may be disposed either in front of (on the subject side) or behind (on the imaging unit 43 side) the aperture stop 48, or may be disposed in front of, behind, or between any of the first to fourth lens groups 44 to 47. Disposing the optical filter 41 at a position where light converges has the advantage of making it possible to reduce the area of ​​the optical filter 41.

[0096] The configuration of the lens unit 42 is not limited to the above configuration and can be selected as appropriate. For example, in addition to a rear-focusing type, it may be an inner-focusing type in which focusing is performed in front of the aperture, or any other type. Furthermore, special lenses such as a fisheye lens or a macro lens can be selected as appropriate in addition to a zoom lens.

[0097] The imaging unit 43 has a glass block 49 and a light receiving element 50. The glass block 49 is a glass block that includes a low-pass filter, a face plate, a color filter, etc. The light receiving element 50 is a sensor unit that receives light that has passed through the lens unit, and an imaging element such as a CCD or CMOS can be used. Alternatively, an optical sensor such as a photodiode can be used, and any device that acquires and outputs information on the intensity or wavelength of light can be used as appropriate.

[0098] 10(a), when the optical filter 41 is incorporated into the lens unit 42, the drive device for the EC element (not shown) may be disposed inside or outside the lens unit 42. When the drive device is disposed outside the lens unit 42, the EC element in the lens unit 42 and the drive device are connected via wiring to control the drive.

[0099] Furthermore, in the configuration of the imaging device described above, the optical filter 41 is disposed inside the lens unit 42. However, the present invention is not limited to this configuration, and it is sufficient that the optical filter 41 is disposed in an appropriate location inside the imaging device, and the light receiving element 50 is disposed so as to receive light that has passed through the optical filter 41.

[0100] For example, as shown in Fig. 10(b), the imaging unit 43 may have an optical filter 41. Fig. 10(b) is a diagram for explaining the configuration of another example of the imaging device of the present invention, and is a schematic diagram of the configuration of an imaging device having the optical filter 41 in the imaging unit 43. In Fig. 10(b), for example, the optical filter 41 is arranged immediately before the light receiving element 50. When the imaging device itself has the optical filter 41 built in, the connected lens unit 42 itself does not need to have the optical filter 41, so it is possible to configure a dimmable imaging device using an existing lens unit 42.

[0101] The imaging device of the present invention can be applied to products that combine light intensity adjustment and a light receiving element, such as cameras, digital cameras, video cameras, and digital video cameras, as well as to products that have a built-in imaging device, such as mobile phones, smartphones, PCs, and tablets. According to the imaging device of the present invention, by using the optical filter of the present invention as a dimming component, it is possible to appropriately vary the amount of dimming using a single filter, which has the advantages of reducing the number of components and saving space.

[0102] <Window materials> The window material of the present invention includes the EC element of 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. Examples of the active element include a transistor. The transistor may have an oxide semiconductor such as InGaZnO in its active region. The window according to this embodiment may also be called a variable transmittance window.

[0103] Fig. 11(a) is a schematic diagram showing a light control window as a window material using the EC element of the present invention, and Fig. 11(b) is a schematic diagram showing the A-A' area of ​​Fig. 11(a), i.e., a cross section in the thickness direction of the central portion. The light control window of this embodiment consists of an EC element 11, transparent plates 61a and 61b that sandwich the EC element 11, and a frame 62 that surrounds and integrates the entire element. The EC element 11 has a drive unit (not shown), which may be integrated within the frame 62 or may be located outside the frame 62 and connected to the EC element 11 via wiring.

[0104] The transparent plates 61a and 61b can be made of any material with high light transmittance, but a glass material is preferable considering their use as windows. The frame 62 can be made of any material, but any material that covers at least a portion of the EC element 11 and has an integrated form can be considered a frame. In Figure 11, the EC element 11 is a component independent of the transparent plates 61a and 61b, but for example, the transparent substrates 26 and 27 of the EC element 11 can also be considered as the transparent plates 61a and 61b.

[0105] 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 views from the outside into the room. In addition to glass windows for buildings, such light-control windows can also be used as windows for vehicles such as automobiles, trains, airplanes, and ships.

[0106] Thus, the EC device of the present invention can be used in optical filters, lens units, imaging devices, window materials, and the like. Furthermore, by providing a reflective member on one of the light paths of the EC element, it can be made into an electrochromic mirror (EC mirror). EC mirrors may be installed in automobiles as anti-glare mirrors. EC mirrors can be constructed by having the EC element of the present invention and a reflective member disposed 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 transparent electrodes of the EC element or via another transparent member. [Example]

[0107] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples. Specific examples of the anodic EC compound and cathodic EC compound used in this example are shown below. However, the EC compounds used in the present invention are not limited to these. EC compounds (2), (4), and (5) are anodic EC compounds, dihydrophenazine derivatives, which are aromatic amine derivatives, and were synthesized by the method described in WO 2020 / 121845. EC compounds (6) to (9) are cathodic EC compounds, viologen derivatives, which are pyridine derivatives. EC compounds (6) and (7) were synthesized by the method described in WO 2020 / 121845, EC compound (8) was synthesized by the method described in JP 2016-155802 A, and EC compound (9) was synthesized by the method described in JP 2017-021327 A.

[0108] [ka]

[0109] [ka]

[0110] (Fabrication of EC element) An EC device having the configuration shown in FIG. 2 was fabricated by the following steps. (1) Fabrication of EC element body: First, two sheets of transparent conductive glass coated with an indium-doped tin oxide (ITO) film were prepared. Next, a thermosetting epoxy adhesive mixed with 30 μm spacer beads was applied to the periphery of the transparent conductive glass as a sealant 25. After that, two sheets of transparent conductive glass 26 and 27 were overlapped so that the ITO films (first electrode 21, second electrode 22) faced each other, and the adhesive was cured by heating, bonding substrate 26 and substrate 27 together. A portion where the sealant was not applied was created to serve as an injection port.

[0111] (2) Injection of electrolyte solution: The anodic EC compound and cathodic EC compound were dissolved in a 10 wt% polymethyl methacrylate solution in propylene carbonate to achieve the dimmed concentration (unit: mmol / L) listed in Table 1. Figure 12(a) shows the change in molar absorption coefficient Δε (the molar absorption coefficient of the colored compound minus the molar absorption coefficient of the bleached compound) for EC compounds (2), (4), and (5), and Figure 12(b) shows the change in molar absorption coefficient Δε (the molar absorption coefficient of the colored compound minus the molar absorption coefficient of the bleached compound) for EC compounds (2), (4), and (5) in this solution. The anodic EC compounds in this solution were three types: (2), (4), and (5), and each had a peak in the colored compound spectrum in the B, G, and R regions of the target image sensor with the spectral sensitivity shown in Figure 4(a).

[0112] [Table 1]

[0113] Next, an electrolyte solution containing the EC compound was injected through the injection port of the EC element body, and then sealed with the thermosetting epoxy adhesive to obtain an EC element. max ) was approximately 1.8 (ND64) on average from 425 nm to 680 nm. Variable optical density (ΔOD A ) spectrum is shown in Figure 13. Also, the index RG max and R ΔOD (ΔOD A Ratio of WΔOD (ΔOD with wavelength width A Table 2 shows the average ratio of

[0114] [Table 2]

[0115] From FIG. 13, the ΔOD of the anodic EC compound of the example AIt can be seen that the spectrum is spread over a wider wavelength range than that of the comparative examples. A The spectrum shows that the absorption is relatively concentrated around 500 nm, as is often seen in colored bodies of common dihydrophenazine derivatives. max The value of RG was 1.21 or less in Example 1 and 1.37 or less in Example 2. max The value of was greater than 1.37.

[0116] R ΔOD (ΔOD A When we look at the ratio of ΔOD A (460nm) and ΔOD A The ratio of ΔOD (550 nm) was 1.44 or less in both the Examples and Comparative Examples. A (605 nm) and ΔOD A The ratio of the wavelength to the incident light (510 nm) was 1.41 or less in Example 1 and 1.72 or less in Example 2. In contrast, in Comparative Examples 1 and 2, the ratio was greater than 1.72.

[0117] R WΔOD (ΔOD with wavelength width A Looking at the ratio of the average of ΔOD A (average 445nm~475nm) and ΔOD A The ratio of ΔOD (average of 535 nm to 565 nm) was 1.45 or less in both the Examples and Comparative Examples. A (590nm~620nm average) and ΔOD A The ratio of the total wavelength (average wavelength of 495 nm to 525 nm) was 1.37 or less in Example 1 and 1.65 or less in Example 2. In contrast, in Comparative Examples 1 and 2, the ratio was greater than 1.65.

[0118] (3) Durability of EC element and change in white balance gain A voltage of 0.7 V was applied between the first and second electrodes of the EC element in a constant temperature and humidity chamber at 60°C and 90% RH to color it. After 500 hours, the first and second electrodes were short-circuited to bleach it. It was confirmed that the EC element retained color, primarily due to absorption by the anodic EC compound. In the optical device shown in Figure 1, which has an image sensor with the spectral sensitivity shown in Figure 4(a), natural daylight was used as the light source. Table 3 shows the maximum change in white balance gain (ΔWBG) relative to the white balance gain of the bleached EC element before the durability test.

[0119] [Table 3]

[0120] The maximum value of the white balance gain change was 1.0% in Example 1 and 3.6% in Example 2. This confirmed that in the optical device using the EC element of Example 1, the charge imbalance color residue caused by the durability test was at a level that was difficult to perceive. Also, in the optical device using the EC element of Example 2, it was confirmed that the charge imbalance color residue caused by the durability test was at a level that was difficult to clearly perceive. In contrast, the maximum value of the white balance gain change in Comparative Examples 1 and 2 exceeded 5%. This confirmed that in the optical devices using the EC elements of Comparative Examples 1 and 2, the charge imbalance color residue caused by the durability test was at a level that was clearly perceivable.

[0121] From this example, the following effects were confirmed. (A) Charge imbalance index RG max Using this method, the type and concentration of the anodic EC compound, a low molecular weight organic compound, is selected so that the variable optical density spectrum of the anodic EC compound is 1.21 or less. This makes it possible to reduce the level at which the charge imbalance color residue that occurs during durability tests is difficult to notice. Similarly, RG maxBy selecting the type and concentration of the anodic EC compound so that the difference is 1.37 or less, the charge imbalance color residue that occurs in the durability test can be reduced to a level that is not clearly noticeable.

[0122] (B) The ratio of the variable optical density of the anodic EC compound at a specific wavelength, which is a simple indicator of the likelihood of charge imbalance color retention, is used to select the type and concentration of the anodic EC compound, a low-molecular-weight organic compound. A (460nm) and ΔOD A (550nm) the maximum ratio of 1.44 or less, and ΔOD A (605 nm) and ΔOD A By setting the maximum value of the ratio to (510 nm) to 1.41 or less, it is possible to make the charge imbalance color residue that occurs in the durability test less noticeable. A (460nm) and ΔOD A (550nm) the maximum ratio of 1.90 or less, and ΔOD A (605 nm) and ΔOD A By setting the maximum value of the ratio to (510 nm) to 1.72 or less, it is possible to set the level at which charge imbalance color residue that occurs in durability tests is not clearly noticeable.

[0123] (C) The type and concentration of the anodic EC compound, which is a low molecular weight organic compound, are selected using the ratio of the average values ​​of the variable optical densities in a specific wavelength range of the anodic EC compound, which is a simple indicator of the likelihood of charge imbalance color retention. A (average 445nm~475nm) and ΔOD A The maximum ratio of ΔOD (average of 535 nm to 565 nm) is 1.45 or less. A (590nm~620nm average) and ΔOD A By setting the maximum value of the ratio to (average of 495 nm to 525 nm) to 1.37 or less, it is possible to make the charge imbalance color residue that occurs in the durability test less noticeable. A (average 445nm~475nm) and ΔOD A The maximum ratio of ΔOD (average of 535 nm to 565 nm) is 1.90 or less.A (590nm~620nm average) and ΔOD A By setting the maximum value of the ratio to (average of 495 nm to 525 nm) to 1.65 or less, it is possible to achieve a level at which residual charge imbalance that occurs in durability tests is not clearly noticeable. [Explanation of symbols]

[0124] 11: electrochromic (EC) element, 12: photodetector, 21: first electrode, 22 : second electrode, 23: electrochromic (EC) layer, 30: driving device, 41: optical filter filter, 42: lens unit, 50: light receiving element

Claims

1. An electrochromic device comprising a first electrode, a second electrode, and an electrochromic layer disposed between the first electrode and the second electrode, wherein the electrochromic layer comprises a plurality of anodic electrochromic compounds which are low-molecular organic compounds, and a cathodic oxidation-reduction material, The electrochromic element is intended for a photodetector having a plurality of detection light wavelength regions, The normalized variable transmittance obtained by combining the absorptions of the plurality of anodic electrochromic compounds and expressed by the following formula is T A (λ), and the T when the charge balance in the electrochromic layer is normal. A The ratio of the RGB signal ratio obtained from (λ) and the sensitivity of the photodetector when the electrochromic element is in a transmitting state to when the plurality of anodic electrochromic compounds are in a colored state is represented by the following formula G: RI / G RT , G RT / G RI , G BI / G BT , G BT / G BI RG, which is the maximum value of max An electrochromic element characterized in that: [Equation 1] ΔOD Aave (λ): ΔOD max Normalized variable optical density ΔOD normalized by B ave Contribution of colored bodies of anodic EC compounds in B: Average variable optical density in the effective wavelength range of the photodetector ΔOD max : Effective maximum variable optical density of the electrochromic element G RI =S GI / S RI G RT =S GT / S RT G BI =S GI / S BI G BT =S GT / S BT S RT : The intensity of the signal detected in the red wavelength region transmitted through the electrochromic element in the transmitting state when the charge balance is normal and detected by the photodetector S GT : Detected signal intensity in the green wavelength region that is transmitted through the electrochromic element in a transmitting state when the charge balance is normal and detected by the photodetector S BT : Detected signal intensity in the blue wavelength region that is transmitted through the electrochromic element in a transmitting state when the charge balance is normal and detected by the photodetector S RI : The intensity of a signal detected in the red wavelength region transmitted through the anodic electrochromic compound in a colored state when the charge balance is normal and detected by the photodetector S GI : The intensity of a detected signal in the green wavelength region that is transmitted through the anodic electrochromic compound in a colored state when the charge balance is normal and detected by the photodetector S BI : The intensity of the detected signal in the blue wavelength region that is transmitted through the anodic electrochromic compound in a colored state when the charge balance is normal and detected by the photodetector

2. The RG max 2. The electrochromic device according to claim 1, wherein the value of .lambda. is 1.21 or less.

3. 3. The electrochromic device according to claim 1, wherein the plurality of anodic electrochromic compounds have variable optical density spectrum peaks in the respective plurality of detection light wavelength regions of the photodetector.

4. The anodic electrochromic compound is a dihydrophenazine derivative.

4. An electrochromic device according to claim 1, wherein the electrochromic device is a polyimide.

5. The electrochromic composition is characterized in that three or more kinds of the anodic electrochromic compounds are used.

5. The electrochromic device according to claim 1, wherein the electrochromic device is a polyimide film.

6. The maximum value between the transmission state and the dimming state of the electrochromic element during normal use 6. The electrochromic device according to claim 1, wherein the light-extinction ratio (transmitting state / light-extinction state) is 8 or more.

7. 7. The electrochromic device according to claim 6, wherein the light extinction ratio is 32 or more.

8. 8. An optical filter comprising: the electrochromic element according to claim 1; and an active element connected to the electrochromic element.

9. An optical filter comprising: the electrochromic element according to claim 1; and a driving device for driving the electrochromic element.

10. 10. A lens unit comprising: the optical filter according to claim 8; and an imaging optical system having a plurality of lenses.

11. 10. An imaging device comprising: the optical filter according to claim 8; and a light receiving element that receives light that has passed through the optical filter.

12. A window material comprising: the electrochromic element according to claim 1; and an active element connected to the electrochromic element.

13. 8. An electrochromic mirror comprising: the electrochromic element according to claim 1; and a reflective member disposed inside or outside the electrochromic element.

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