JP2019045635A - Dimming device, dimming window, and dimming method - Google Patents

Abstract

To provide a dimming device, a dimming window, and a dimming method which are capable of independently controlling the transmittance of light of a near infrared ray region and the transmittance of light of the visible ray region.SOLUTION: A dimming device includes: a first electrochromic electrode; a second electrochromic electrode provided in opposing to the first electrochromic electrode; an electrolyte layer disposed between the first electrochromic electrode and the second electrochromic electrode; and an auxiliary electrode electrically connected to the first electrochromic electrode and the second electrochromic electrode via an electrolyte layer. The transmittance of light of a near infrared ray region is controlled by applying a voltage between the first electrochromic electrode and the auxiliary electrode, and the transmittance of the light of the near infrared ray region and the transmittance of the visible ray region are controlled each independently.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a light control device, a light control window, and a light control method.

  In office buildings and ordinary houses, the problem was that much of the energy used for cooling and heating was lost due to the movement of heat through the windows.

  Therefore, attempts have been made to improve the heat insulation performance by sandwiching a layer of air or an inert gas between two glasses in order to save energy in the window. For example, the adoption of Low-E double glazing, which is a combination of double glazing and a Low-E (Low Emitance) film such as a metal or oxide that reflects near infrared rays, is progressing.

  However, when the near-infrared light is reflected to improve the heat shielding performance, the cooling load in summer can be reduced. However, since the near-infrared light cannot be taken indoors in the winter, there is a problem that the heating load increases. On the other hand, if the heat shielding performance is lowered, there arises a trade-off problem that the cooling load in summer increases. Therefore, it has been difficult to obtain a sufficient energy saving effect throughout the year in Japan where the temperature difference due to the season is large with only Low-E double-glazed glass.

  As a measure for solving this problem, development of a smart window (light control glass) capable of changing the transmittance of the window glass is underway. In particular, an electrochromic (EC) smart window using an electrochemical oxidation-reduction reaction has high controllability because the transmittance can be changed electrically. For example, strong sunlight in summer can be cut off to reduce cooling load, and in winter, sunlight can be transmitted to reduce heating load.

  However, in the conventional EC smart window, the transmittance in the wavelength range from visible light to near infrared is simultaneously increased or decreased, and it is difficult to control the transmittance for each wavelength. For this reason, if the transmittance | permeability of a window glass is reduced in order to reduce the cooling load in summer, indoors will become dark and lighting will be needed. If the transmittance is increased in order to reduce the heating load in winter, it is difficult to achieve both a reduction in heating and cooling load and a reduction in lighting load or occupant comfort, such as the sunlight being too bright and causing problems in desk work. There was a problem.

  In order to solve this problem, methods for controlling visible light and near infrared light by combining two EC cells have been proposed (Patent Documents 1 and 2). Also, a method for controlling visible light and near-infrared light by making an EC electrode that absorbs visible light and an EC electrode that absorbs near-infrared light facing each other or by making an EC electrode and a thermochromic layer face each other has been proposed. (Patent Documents 1-3). In addition, a method of arranging a third electrode in the EC element has been proposed (Patent Documents 4-8).

Special table 2014-523000 gazette Special table 2014-518405 gazette JP 2013-246374 A JP-A 61-147237 JP 61-174517 A JP-A 61-179422 Japanese Patent Laid-Open No. 2006-224441 JP 2017-16110 A

  However, in the method of combining two EC cells described in Patent Documents 1 and 2, the element structure becomes complicated (a structure in which a total of four glass substrates are laminated). It has been regarded as a problem that the effect of reducing the heating load is hindered. Further, in the method of controlling visible light and near infrared light described in Patent Documents 1-3, it has been difficult to independently control the transmittances of visible light and near infrared light to optimum values. Moreover, although the method of disposing the third electrode in the EC element described in Patent Documents 4-8 solves the problem of color residue (decoloration failure), similarly, it transmits visible light and near infrared light. The problem was left in the point which controls each rate to the optimal value independently.

  The present invention has been made in view of the above circumstances, and a light control device and a light control window capable of independently controlling the light transmittance in the near-infrared region and the light transmittance in the visible light region, respectively. And it aims at providing the light control method.

In order to achieve the above object, a light control device according to the first aspect of the present invention provides:
A first electrochromic electrode;
A second electrochromic electrode provided opposite to the first electrochromic electrode;
An electrolyte layer disposed between the first electrochromic electrode and the second electrochromic electrode;
An auxiliary electrode electrically connected to the first electrochromic electrode and the second electrochromic electrode via the electrolyte layer;
With
By applying a voltage between the first electrochromic electrode and the auxiliary electrode, the light transmittance in the near infrared region is controlled,
By applying a voltage between the second electrochromic electrode and the auxiliary electrode, the light transmittance in the visible light region is controlled,
The light transmittance in the near infrared region and the light transmittance in the visible light region are each controlled independently.
It is characterized by that.

For example, in the first electrochromic electrode, in the low transmittance state, the absorption in the near infrared region is larger than the absorption in the visible light region,
In the second electrochromic electrode, in the low transmittance state, the absorption in the visible light region is larger than the absorption in the near infrared region.

  For example, the first electrochromic electrode includes a thin film selected from the group consisting of tungsten oxide, molybdenum oxide, titanium oxide, and composite oxides thereof.

  For example, the thickness of the thin film of the first electrochromic electrode is not less than 50 nm and not more than 1 μm.

  For example, the second electrochromic electrode includes a thin film selected from the group consisting of a composite oxide containing nickel oxyhydroxide, nickel hydroxide, nickel oxide and nickel oxide.

  For example, the thickness of the thin film of the second electrochromic electrode is 50 nm or more and 1 μm or less.

  For example, the auxiliary electrode is selected from the group consisting of iron oxyhydroxide, iron hydroxide, iron oxide, iridium oxide, and complex oxides thereof.

  For example, the charge capacity of the auxiliary electrode is larger than the charge capacity of the first electrochromic electrode and the second electrochromic electrode.

The light control window according to the second aspect of the present invention is:
The light control apparatus which concerns on the 1st viewpoint of this invention is provided.

For example, the first electrochromic electrode and the second electrochromic electrode are installed in a central portion of a window surface,
The auxiliary electrode is installed in the window frame portion.

For example, the first electrochromic electrode and the second electrochromic electrode are installed in a central portion of a window surface,
The auxiliary electrode is installed in the electrolyte layer.

The dimming method according to the third aspect of the present invention is:
By applying a voltage between the first electrochromic electrode and the auxiliary electrode, the light transmittance in the near infrared region is controlled,
By applying a voltage between the second electrochromic electrode provided opposite to the first electrochromic electrode and the auxiliary electrode, the light transmittance in the visible light region is controlled,
The auxiliary electrode is electrically connected to the first electrochromic electrode and the second electrochromic electrode via an electrolyte layer disposed between the first electrochromic electrode and the second electrochromic electrode. Connected,
The light transmittance in the near infrared region and the light transmittance in the visible light region are each controlled independently.
It is characterized by that.

  According to the present invention, it is possible to provide a light control device, a light control window, and a light control method capable of independently controlling the light transmittance in the near-infrared region and the light transmittance in the visible light region. it can.

It is a figure which illustrates roughly the light modulation apparatus of this embodiment. It is a figure explaining the state of control of the light transmittance of the near-infrared area | region and the light transmittance of the visible light area | region of the light modulation apparatus of this embodiment, (a) is the transmittance | permeability of visible light and a near-infrared area | region. (B) is a near-infrared blocking state in which the transmittance in the visible light region is high but the transmittance in the near-infrared region is low, and (c) is a transmission in the visible light region that has a high transmittance in the near-infrared region. The rate is a low visible light blocking state, and (d) is a diagram showing a state where both the visible light and the near infrared region have low transmittance, and both the visible light and the near infrared ray are blocked. It is the figure explaining the oxidation reduction reaction of the 1st EC electrode and the 2nd EC electrode, (a) is the 1st EC electrode is in an oxidation state (WO ₃ ), the 2nd EC electrode is in a reduction state (Ni (OH) ₂ ), The transparent state in which the transmittance of both the 1EC electrode and the second EC electrode is high, (b) is the first EC electrode is in the reduced state (H _x WO ₃ ), and the second EC electrode is also in the reduced state (Ni (OH) ₂ ). The near-infrared shielding state in which the transmittance of the electrode is low and the transmittance of the second EC electrode is high, (c) is the first EC electrode is in the oxidized state (WO ₃ ), and the second EC electrode is also in the oxidized state (NiOOH). Visible light blocking state in which the transmittance is high and the transmittance of the second EC electrode is low, (d) is the first EC electrode is in a reduced state (H _x WO ₃ ), the second EC electrode is in an oxidized state (NiOOH), Second EC electrode transmission It is a figure showing the state which blocked | interrupted both visible light and near-infrared rays with both low rates. It is the figure explaining the form which has arrange | positioned the elongate auxiliary electrode in the window frame part of the light control window, (a) is a front view, (b) is a figure showing sectional drawing. It is the figure explaining the form which installed the wire-shaped auxiliary electrode in parallel inside the light control window, (a) is a front view, (b) is a figure showing sectional drawing. It is the figure explaining the form which installed the wire-shaped auxiliary electrode in the inside of the light control window in the grid | lattice form, (a) is a front view, (b) is a figure showing sectional drawing. It is a graph showing the transmission spectrum in the high transmittance state (at the time of decoloring) and the low transmittance state (at the time of coloring) of the WO ₃ thin film, (a) is a film thickness of 100 nm, (b) is a film thickness of 200 nm, (c). FIG. 6 is a graph showing a transmission spectrum at a film thickness of 300 nm. It is a graph showing the transmission spectrum in the high transmittance state (at the time of decoloring) and the low transmittance state (at the time of coloring) of a NiOOH thin film, (a) is a film thickness of 100 nm, (b) is a film thickness of 200 nm, (c) is A film thickness of 300 nm and (d) are graphs showing a transmission spectrum at a film thickness of 400 nm. Is a graph showing the change in transmittance in the high transmittance state (the colored state) (decolorized state) and a low transmittance state due to the film thickness difference in the WO ₃ film and NiOOH film, (a) shows the WO ₃ film, ( b) is a graph showing a change in transmittance in a NiOOH thin film. Is a graph showing the transmission spectrum when the combination of the NiOOH thin WO ₃ thin film and the thickness 100nm of thickness 200 nm, (a) is WO ₃ film is the oxidation state _(WO 3), NiOOH films reduced state ( Ni is an _{(OH) 2),} both a high transmittance state, (b) the WO ₃ film has low transmittance in a reduced state _(H x WO _3), NiOOH films reduced state (Ni _(OH) 2) (C) is a state in which the WO ₃ thin film is in an oxidized state (WO ₃ ) and has a high transmittance, a NiOOH thin film is in an oxidized state (NiOOH) and has a low transmittance, and (d) is a state in which the WO ₃ thin film is It is a graph showing a transmission spectrum in a reduced state (H _x WO ₃ ), a NiOOH thin film is in an oxidized state (NiOOH), and the WO ₃ thin film and the NiOOH thin film have low transmittance. It is the graph which measured the mobile charge density of various transition metal oxide thin films. It is a photograph figure of the light control apparatus of this embodiment, (a) is a state with high transmittance (decoloring) in both the WO ₃ thin film and the NiOOH thin film, (b) is a low transmittance (colored) of the WO ₃ thin film, and NiOOH The thin film has a high transmittance (decoloration), (c) has a high transmittance of the WO ₃ thin film (decoloration), and the NiOOH thin film has a low transmittance (coloration). (D) shows both the WO ₃ thin film and the NiOOH thin film. It is a photograph figure showing a state with low transmittance (coloring).

  First, the light control device of this embodiment will be described in detail.

  As shown in FIG. 1, the light control device according to the present embodiment includes a first electrochromic electrode (hereinafter referred to as “first EC electrode”), a second electrochromic electrode (hereinafter referred to as “second EC electrode”), An electrolyte layer and an auxiliary electrode are provided. A power source is connected to the first EC electrode, the second EC electrode, and the auxiliary electrode.

  In the present specification, the “low transmittance state” and the “low transmittance state” represent a state in which the transmittance of the electrode is relatively low. The “low transmittance state” and the “low transmittance state” may be, for example, a state where the average transmittance in the visible light region or the near infrared region is 50% or less, or, for example, a colored state. However, the present invention is not limited to these.

  In this specification, the “high transmittance state” and the “high transmittance state” represent a state in which the transmittance of the electrode is relatively high. The “high transmittance state” and the “high transmittance state” may be, for example, a state where the average transmittance in the visible light region or the near infrared region is 50% or more, or, for example, a decolored state or a transparent state Although it may be a state, it is not limited to these.

  As the first EC electrode, electrochromic can transmit visible light and near infrared light at a predetermined transmittance in a high transmittance state, and has a large absorption in the near infrared region compared to absorption in the visible light region in a low transmittance state. Material is used. The electrochromic material used for the first EC electrode may be an inorganic compound or an organic compound. Moreover, the electrochromic material used for the first EC electrode may contain a heat ray absorbent, an adhesive strength adjusting agent, and the like.

  As an inorganic compound used for the first EC electrode, visible light and near-infrared light can be transmitted with a predetermined transmittance in a high transmittance state, and in the near-infrared region in comparison with absorption in the visible light region in a low transmittance state. As long as it is an inorganic compound that absorbs a large amount of water, it can be used without any particular limitation. For example, it is selected from the group consisting of tungsten oxide, molybdenum oxide, titanium oxide, and composite oxides thereof.

  As an organic compound used for the first EC electrode, visible light and near infrared light can be transmitted at a predetermined transmittance in a high transmittance state, and near infrared region compared to absorption in the visible light region in a low transmittance state. Any organic compound that absorbs a large amount can be used without particular limitation, and examples thereof include polyamine imide compounds and polythiophene compounds.

  The first EC electrode includes, for example, a thin film made of the above material. Since the transmittance follows the Lambert-Beer law, the transmittance decreases exponentially as the film thickness of the first EC electrode increases. For this reason, a larger transmittance change is obtained as the film thickness is increased. However, at the same time, the transmittance in a high transmittance state is also lowered, so it is necessary to select an optimum film thickness. From the viewpoint of maintaining an appropriate transmittance change and maintaining the transmittance in the visible light or near infrared region at a certain level or higher even in a high transmittance state, the film thickness of the thin film of the first EC electrode is, for example, 50 nm or more and 1 μm or less, Preferably they are 50 nm or more and 300 nm or less.

  As shown in FIG. 1, the second EC electrode is provided opposite to the first EC electrode, and can transmit visible light and near infrared light with a predetermined transmittance in a high transmittance state, and near in a low transmittance state. An electrochromic material that has a larger absorption in the visible light region than that in the infrared region is used. The electrochromic material used for the second EC electrode may be an inorganic compound or an organic compound. Further, the electrochromic material used for the second EC electrode may contain a heat ray absorbent, an adhesive strength adjusting agent, and the like.

As an inorganic compound used for the second EC electrode, visible light and near-infrared light can be transmitted with a predetermined transmittance in a high transmittance state, and visible light region in a low transmittance state as compared with absorption in the near-infrared region. An inorganic compound that absorbs a large amount of oxygen can be employed without any particular limitation. For example, a composite oxide containing nickel oxyhydroxide (NiOOH), nickel hydroxide (Ni (OH) ₂ ), nickel oxide (NiO), and nickel oxide Selected from the group consisting of nickel hydroxide and hydrated zirconium oxide (ZrO ₂ .nH ₂ O). The inorganic compound used for the second EC electrode is a metal complex such as Prussian blue (Fe ₄ [Fe (CN) ₆ ] ₃ ), Prussian blue analog in which a part of Prussian blue iron is replaced with nickel or indium ( Ni _x [Fe (CN) ₆ ] _y or In _x [Fe (CN) ₆ ] _y ) or the like may be used.

  As an organic compound used for the second EC electrode, visible light and near infrared light can be transmitted at a predetermined transmittance in a high transmittance state, and in the low transmittance state, the visible light region is larger than the absorption in the near infrared region. May be employed without particular limitation as long as the organic compound absorbs a large amount of, for example, polypyrrole compound, polyacetylene compound, polythiophene compound, polyparaphenylene vinylene compound, polyaniline compound, polyethylenedioxythiophene compound, metal phthalocyanine compound, viologen compound, Examples thereof include viologen salt compounds, ferrocene compounds, and dimethyl terephthalate compounds.

  The second EC electrode includes, for example, a thin film made of the above material, and the film thickness is, for example, 50 nm or more and 1 μm or less for the same reason as the first EC electrode described above.

  As shown in FIG. 1, the electrolyte layer is disposed between the first EC electrode and the second EC electrode, and serves to electrically connect the first EC electrode and / or the second EC electrode and the auxiliary electrode. The material of the electrolyte layer can be used without particular limitation as long as it does not affect the light transmission in the first EC electrode and the second EC electrode and plays a role as an electrolyte having high ion conductivity. For example, sulfonated tetrafluoroethylene (trade name: Nafion) dispersed in a solvent (for example, a mixed solution of water and propyl alcohol); polystyrene-block-poly (ethylene-ran-butylene) -block-polystyrene sulfone Acid solution; Proton-conducting electrolytes such as solid films formed by evaporating these solvents; Lithium salts such as lithium perchlorate and lithium borofluoride added to solvents such as propylene carbonate, ethylene carbonate, and γ-butyrolactone Lithium ion conductive electrolyte or the like is used.

  The auxiliary electrode is electrically connected to the first EC electrode and the second EC electrode via the electrolyte layer. By providing the auxiliary electrode, the first EC electrode and the second EC electrode can be controlled independently.

  The auxiliary electrode plays a role of accumulating charges that move with the redox reaction of the first EC electrode and the second EC electrode. As the material of the auxiliary electrode, a material having high electrochemical activity and a large charge capacity is used, and preferably has a charge capacity larger than that of the first EC electrode and the second EC electrode and is chemically stable. A material that does not react with the material of the electrolyte layer is used. The material of the auxiliary electrode is selected from the group consisting of, for example, iron oxyhydroxide, iron hydroxide, iron oxide, iridium oxide, and complex oxides thereof. Inorganic compounds used for the auxiliary electrode are titanium oxide, vanadium oxide, chromium oxide, manganese oxide, cobalt oxide, nickel oxide, tungsten oxide, molybdenum oxide, ruthenium oxide, rhodium oxide, Prussian blue, Prussian blue analog, etc. Also good. In addition, polyamine imide compounds, polypyrrole compounds, polyacetylene compounds, polythiophene compounds, polyparaphenylene vinylene compounds, polyaniline compounds, polyethylene dioxythiophene compounds, metal phthalocyanine compounds, viologen compounds, viologen salt compounds, ferrocene compounds, dimethyl terephthalate compounds, etc. It may be an organic compound.

  An example of light transmittance and color change in the light control device of this embodiment will be described with reference to FIG. In the high transmittance state (decolored state), both the first EC electrode and the second EC electrode are in a transparent state and transmit both visible light and near infrared rays (FIG. 2A). By applying a voltage between the first EC electrode and the auxiliary electrode, the first EC electrode is in a low transmittance state (colored), and absorption in the near infrared region is larger than absorption in the visible light region. Near-infrared rays are blocked and visible light is transmitted (FIG. 2B). On the other hand, by applying a voltage between the second EC electrode and the auxiliary electrode, the second EC electrode is in a low transmittance state (colored), and the absorption in the visible light region is larger than the absorption in the near infrared region. Therefore, visible light is blocked and near infrared rays are transmitted (FIG. 2C). By applying a voltage between the first EC electrode and the auxiliary electrode and between the second EC electrode and the auxiliary electrode, the first EC electrode and the second EC electrode are in a low transmittance state (colored), and near infrared and visible light. Since the absorption of both of the regions becomes large, both near infrared rays and visible light are blocked (FIG. 2D). Note that the transmittance of each electrode can be continuously changed depending on the polarity of the power supply voltage, the magnitude of the voltage to be applied, the time for which the voltage is applied, and the like. In this way, by applying a voltage between the first EC electrode and the auxiliary electrode, the transmittance of light in the near-infrared region (for example, wavelength 0.7 to 2.5 μm) is controlled, and the second EC electrode and the auxiliary electrode are controlled. By applying a voltage between the electrodes, the light transmittance in the visible light region (for example, wavelength 0.4 to 0.7 μm) is controlled, and the light transmittance in the near infrared region and the light in the visible light region are controlled. The transmittance of each is controlled independently.

The oxidation-reduction reaction of the first EC electrode and the second EC electrode will be described with reference to FIG. FIG. 3 shows a light control device when a WO ₃ thin film is used as the first EC electrode, a NiOOH thin film is used as the second EC electrode, Fe ₂ O ₃ is used as the auxiliary electrode, and sulfonated tetrafluoroethylene is used as the electrolyte layer. Sulfonated tetrafluoroethylene is a proton-conductive electrolyte, and the WO ₃ thin film, NiOOH thin film, and Fe ₂ O ₃ thin film used as electrodes are respectively
The redox reaction of Here, the oxidized state WO ₃ is a high transmittance state (transparent), the reduced state H _x WO ₃ is a low transmittance state (blue), and the oxidized state NiOOH is a low transmittance state (brown), a reduced state. Ni (OH) ₂ is in a high transmittance state (transparent). Fe ₂ O ₃ and Fe ₃ O ₄ are yellow to brown and do not cause a significant color change. When a positive voltage is applied to the first EC electrode (WO ₃ thin film) and a negative voltage is applied to the auxiliary electrode (Fe ₂ O ₃ ), the first EC electrode enters a high transmittance state (decolored), and the second EC electrode (NiOOH thin film) When a negative voltage and a positive voltage are applied to the auxiliary electrode (Fe ₂ O ₃ ), the second EC electrode enters a high transmittance state (decolored), and both the first EC electrode and the second EC electrode enter a high transmittance state (transparent state). (FIG. 3 (a)). By applying a negative voltage to the first EC electrode and a positive voltage to the auxiliary electrode, H _x WO _{3 in} the reduced state becomes blue, and the first EC electrode enters a low transmittance state (colors) (FIG. 3 (b )). On the other hand, when a positive voltage is applied to the second EC electrode and a negative voltage is applied to the auxiliary electrode, the oxidized NiOOH turns brown and the second EC electrode enters a low transmittance state (colors) (FIG. 3C). ). By applying a negative voltage to the first EC electrode, a positive voltage to the auxiliary electrode, a positive voltage to the second EC electrode, and a negative voltage to the auxiliary electrode, the reduced state H _x WO ₃ becomes blue, NiOOH in an oxidized state turns brown, and both the first EC electrode and the second EC electrode are in a low transmittance state (colored) (FIG. 3D). As described above, the auxiliary electrode exchanges electric charges between the first EC electrode and the second EC electrode through the electrolyte layer.

WO ₃ thin film as the first EC electrode, NiOOH thin film as the second EC electrode, Fe ₂ O ₃ as the auxiliary electrode, and sulfonated tetrafluoroethylene (trade name: Nafion) as the material of the electrolyte layer are dispersed in a mixed solution of water and propyl alcohol. An example of the operation will be described with reference to an example of a dimming device using an apparatus.

When both visible light and near infrared light are transmitted, a positive voltage is applied to the first EC electrode (WO ₃ thin film) and a negative voltage is applied to the auxiliary electrode (Fe ₂ O ₃ ), so that the first EC electrode has a high transmittance. By applying a negative voltage to the second EC electrode (NiOOH thin film) and applying a positive voltage to the auxiliary electrode (Fe ₂ O ₃ ), the second EC electrode is brought into a high transmittance state (decolorization). Thus, both the first EC electrode and the second EC electrode are in a high transmittance state (transparent state). When blocking near-infrared rays and transmitting visible light, a negative voltage is applied to the first EC electrode and a positive voltage is applied to the auxiliary electrode to bring the first EC electrode (WO ₃ thin film) into a low transmittance state. (Colored blue). On the other hand, when blocking visible light and transmitting near infrared rays, applying a positive voltage to the second EC electrode and a negative voltage to the auxiliary electrode makes the second EC electrode (NiOOH thin film) in a low transmittance state. Do (color brown). When blocking both near infrared and visible light, a negative voltage is applied to the first EC electrode, a positive voltage is applied to the auxiliary electrode, a positive voltage is applied to the second EC electrode, and a negative voltage is applied to the auxiliary electrode. As a result, both the first EC electrode (WO ₃ thin film) and the second EC electrode (NiOOH thin film) are brought into a low transmittance state (colored). Thus, by applying a voltage between the first EC electrode and the auxiliary electrode, the light transmittance in the near infrared region is controlled, and by applying a voltage between the second EC electrode and the auxiliary electrode, The light transmittance in the visible light region is controlled, and the light transmittance in the near-infrared region and the light transmittance in the visible light region are independently controlled.

  Next, the light control window of this embodiment is demonstrated.

  The light control window of this embodiment includes the light control device described above. The first EC electrode and the second EC electrode are arranged to face each other, and sunlight has a structure that passes through these and enters the room indoors. The auxiliary electrode is preferably arranged so as not to affect the change in light transmittance, and so as not to interfere with the transmission of sunlight. For example, the auxiliary electrode is arranged in a window frame portion with a reduced area. It arrange | positions by the method of arrange | positioning at the window surface in the shape of a thin wire. The auxiliary electrode can also be used in the form of a thin film or powder.

  Examples of installation of the auxiliary electrode in the light control window are shown in FIGS.

In FIG. 4, the first EC electrode and the second EC electrode are disposed in the center portion of the window surface, and the elongated auxiliary electrode is disposed in the window frame portion of the light control window. Since the oxidation-reduction reaction proceeds by the movement of electrons and ions inside the EC material, the movement speed of the electrons and ions dominates the response speed of the first EC electrode and the second EC electrode. When the auxiliary electrode is installed in the window frame portion shown in FIG. 4, the ion movement distance becomes longer between the first EC electrode and the second EC electrode in the central portion of the window and the auxiliary electrode, and the effective ion resistance is increased. Therefore, the response speed may decrease. Since the resistivity of the transparent electrode with respect to electronic conduction is 10 ⁻³ to 10 ⁻⁴ Ωcm and the film thickness is about 100 nm, the sheet resistance is on the order of 10 to 100 Ω / sq. On the other hand, the resistivity with respect to ionic conduction of a general electrolyte material is 1 to 10 ² Ωcm. Therefore, in this case, by setting the thickness of the electrolyte layer to, for example, about 0.1 to 10 mm, the sheet resistance of the transparent electrode (first EC electrode and second EC electrode) and the electrolyte layer becomes approximately the same, and the response speed decreases. Can be prevented.

  In FIG. 5, wire-like auxiliary electrodes are arranged in parallel in the electrolyte layer between the first EC electrode and the second EC electrode inside the dimming window. Thereby, since the distance between the first EC electrode and the second EC electrode and the auxiliary electrode is shortened, it is possible to prevent the response speed from being lowered even if the thickness of the electrolyte layer is reduced.

  In FIG. 6, wire-like auxiliary electrodes are arranged in a grid pattern in the electrolyte layer between the first EC electrode and the second EC electrode inside the light control window. Thereby, since the distance between the first EC electrode and the second EC electrode and the auxiliary electrode is shortened, it is possible to prevent the response speed from being lowered even if the thickness of the electrolyte layer is reduced.

  By placing a laminated structure of electrolyte membrane / auxiliary electrode / electrolyte membrane with a wire-like auxiliary electrode sandwiched between two solid electrolyte membranes between the first EC electrode and the second EC electrode, The light control window shown in FIG. 5 or 6 can be easily produced.

  Next, the light control method of this embodiment is demonstrated.

  The light control method of this embodiment controls the light transmittance in the near-infrared region by applying a voltage between the first EC electrode and the auxiliary electrode, and sets the voltage between the second EC electrode and the auxiliary electrode. By applying the light, the light transmittance in the visible light region is controlled. The auxiliary electrode is electrically connected to the first EC electrode and the second EC electrode via an electrolyte layer disposed between the first EC electrode and the second EC electrode, and transmits light in the near infrared region and in the visible light region. The light transmittance is controlled independently of each other. The first EC electrode, the second EC electrode, the auxiliary electrode, the electrolyte layer, and the like are the same as described above.

  As described above, in the light control device, the light control window, and the light control method of the present embodiment, a) When both the first EC and the second EC electrodes are in a high transmittance state, visible light and near infrared light are transmitted with a predetermined transmittance. B) When the first EC electrode is in a low transmittance state and the second EC electrode is in a high transmittance state, only near infrared rays are blocked. C) The first EC electrode is in a high transmittance state, and the second EC electrode is in a low transmittance state. It is possible to realize four states: only visible light is blocked in the rate state, and d) both visible light and near infrared are blocked when both the first EC electrode and the second EC electrode are in the low transmittance state. . It is also possible to continuously control the transmittance between the states. In this way, by controlling the transmittance in the visible light region and the near-infrared region independently, in the summer, the near-infrared rays are blocked to reduce the cooling load, and the visible light is partially transmitted to reduce the illumination load. be able to. In the case of a strong western day, both the visible region and the near-infrared region can be blocked to reduce the cooling load to the maximum. On the other hand, sunlight in the visible light region is reduced in winter, but the heating load can be reduced by sufficiently transmitting near infrared rays. On cloudy days, it is possible to achieve optimal transmittance control that keeps high transmittance in both the visible and near-infrared regions and maximizes sunlight.

  In addition, the light control device of this embodiment has a simple structure as compared with the case where two or more conventional EC cells are stacked, and efficiently transmits visible light and near infrared light at a predetermined transmittance in a high transmittance state. Therefore, a high energy saving effect can be obtained.

  Further, in the conventional complementary EC smart window, it is necessary to limit the electrode to a combination of a reduction coloring type in which the transmittance decreases in the reduction state and an oxidation coloring type in which the transmittance decreases in the oxidation state. However, in the light control device of the present embodiment, ions can be moved between the first EC electrode and the auxiliary electrode, and ions can also be moved between the second EC electrode and the auxiliary electrode. The material of the first EC electrode and the material of the second EC electrode may be a combination of reduction coloring EC materials or a combination of oxidation coloring EC materials, and the degree of freedom of electrode material selection can be greatly expanded. Furthermore, unlike the conventional complementary EC smart window, it is not necessary to balance the charge between the two EC electrodes, and therefore, a design that makes the best use of the optical density change of the two EC electrodes is possible.

  The light control device, the light control window, and the light control method of this embodiment can be used for windows in office buildings and general homes. By blocking strong sunlight in summer and reducing the cooling load, and increasing the transmittance in winter, sunlight can be taken indoors and the heating load can be reduced. Furthermore, the energy of indoor lighting can be saved by appropriately controlling the transmittance of visible light in the near-infrared region and the near-infrared region. Moreover, according to the light control window of this embodiment, since the state of the outdoors can be seen without obstructing the field of view like a blind or a curtain, the comfort of the resident is improved. Further, it can be applied to a window of a transportation facility such as an automobile, an aircraft, a railway vehicle, or a ship to save energy. In addition, the light control device of the present embodiment can be applied to an imaging device as an optical shutter capable of independently controlling the transmittance in the visible light region and the near infrared region.

  Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to these examples.

Example 1
A light control device using a tungsten oxide (WO ₃ ) thin film as the first EC electrode and a nickel oxyhydroxide (NiOOH) thin film as the second EC electrode was verified.

First, the relationship between the transmittance and the wavelength was examined for the first EC electrode. As a first EC electrode, a tungsten oxide (WO ₃ ) thin film having a thickness of 100, 200, or 300 nm was formed on a glass substrate with an ITO (Indium Tin Oxide) transparent electrode by a sputtering method. In the production of the WO ₃ thin film, an RF magnetron sputtering apparatus was used, and a metal tungsten target (diameter 2 inches, purity 99.9%) was reactively sputtered in a sputtering gas atmosphere of 100% oxygen. The substrate temperature was room temperature, the sputtering gas pressure was 50 mTorr, and the RF power was 50 W. After oxidation-reduction of the WO ₃ thin film of each film thickness in a 1M H ₂ SO ₄ aqueous electrolyte, an ultraviolet-visible spectrophotometer (manufactured by Hitachi High-Tech Science Co., U-2910) and a Fourier transform infrared spectrophotometer ( The transmission spectrum was measured using JASCO Corporation FT / IR-6100.

The results are shown in FIG. In the oxidized state, it became a high transmittance state (decolored state), and showed a high transmittance of 80% or more in the visible light region. On the other hand, a reduced transmittance state (colored state) is obtained in the reduced state, and a relatively high transmittance of 40 to 60% is maintained in the visible light, particularly in a short wavelength region of 400 to 500 nm. The transmittance was reduced to about%. As a result, it was confirmed that the WO ₃ thin film exhibits a large transmittance change in the near infrared region. In the mid-infrared region of 2.5 μm or more, the transmittance was lowered due to absorption by the glass substrate and reflection by the ITO transparent electrode.

Next, the relationship between the transmittance and the wavelength was examined for the second EC electrode. As the second EC electrode, a nickel oxyhydroxide (NiOOH) thin film having a thickness of 100, 200, 300, or 400 nm was formed on a glass substrate with an ITO transparent electrode by a sputtering method. Similar to the WO ₃ thin film, a NiOOH thin film was produced by reactive sputtering of a metallic nickel target (diameter 2 inches, purity 99.9%) in a sputtering gas atmosphere of 100% water vapor using an RF magnetron sputtering apparatus. . The substrate temperature was room temperature, the sputtering gas pressure was 50 mTorr, and the RF power was 50 W. After the NiOOH thin film of each film thickness was oxidized and reduced in a 1M KOH aqueous solution electrolyte, the transmission spectrum was measured in the air in the same manner as described above.

  The results are shown in FIG. In the reduced state, it became a high transmittance state (decolored state), and showed a high transmittance of about 60 to 80% in the visible light region and the near infrared region. On the other hand, in the oxidized state, it is in a low transmittance state (colored state) and maintains a relatively high transmittance of about 30 to 60% in the near infrared region, but the transmittance is reduced to about 30% or less in the visible light region. Was. As a result, it was confirmed that the NiOOH thin film showed a large transmittance change in the visible light region.

FIG. 9 shows the relationship between the film thickness and the transmittance of the first EC electrode and the second EC electrode. Since the transmittance follows the Lambert-Beer law, the transmittance decreases exponentially as the thickness of the EC electrode increases. For this reason, a larger transmittance change is obtained as the film thickness is increased. However, at the same time, the transmittance in the high transmittance state (during decolorization) also decreases, and it is necessary to select an optimum film thickness. From FIG. 9, it can be seen that both the WO ₃ thin film and the NiOOH thin film have almost no change in transmittance at a film thickness of 50 nm or less, and that the film thickness of 1 μm or more has a transmittance in the visible light or near infrared region of 50 even at the time of decolorization. % Was shown to fall below%.

Next, the relationship between the transmittance and wavelength when a WO ₃ thin film was combined as the first EC electrode and a NiOOH thin film was combined as the second EC electrode was examined. More specifically, the film thickness is 200 nm WO ₃ film serving as the 1EC electrode, the transmission spectrum when the film thickness as the 2EC electrode was used NiOOH thin 100 nm, the light of both the WO ₃ film and NiOOH film Was calculated using the transmittance shown in FIG. 7 and FIG.

The results are shown in FIG. FIG. 10 (a) is a transmission spectrum when both the WO ₃ thin film and the NiOOH thin film are in a decolored state, and it is shown that a high transmittance of 40 to 70% can be obtained from the visible light to the near infrared region. FIG. 10B shows a case where only the WO ₃ thin film of the first EC electrode is colored, and the transmittance in the near infrared region is as low as 20% or less, but a relatively high transmittance of about 40% in the visible light region. It was shown to be obtained. FIG. 10C shows a case where only the NiOOH thin film of the second EC electrode is colored, and the transmittance in the visible light region is reduced to about 20% compared to the transmittance in the near infrared region is about 40%. It was shown that FIG. 10 (d) shows a case where both the WO ₃ thin film and the NiOOH thin film are colored, and it is shown that the transmittance is reduced to about 10% in the entire wavelength region from visible light to near infrared.

(Example 2)
The material of the auxiliary electrode of the light control device was verified. With respect to various transition metal oxides shown in FIG. 11, a thin film having a thickness of 100 nm was prepared by a sputtering method, and the mobile charge density (charge capacity) was evaluated by cyclic voltammetry. Cyclic voltammetry is a method of measuring the current flowing through a sample while changing the potential applied to the sample at a constant rate, and is a measurement method that can know the potential at which an electrode reaction proceeds and the reaction rate. By integrating the measured current value over time, the amount of charge transferred with the electrode reaction can be obtained. This charge amount was normalized by the area of the sample and plotted in FIG. 11 as a moving charge amount per unit area. In the measurement of cyclic voltammetry, Ag / AgCl was used for the reference electrode, Pt was used for the counter electrode, and the potential scanning speed was 20 mV / s.

The results are shown in FIG. It was found that the charge capacities of iron oxide (Fe ₂ O ₃ ) and iridium oxide (IrO _x ) were large. When compared with the same film thickness as NiOOH used for the second EC electrode, it was shown that Fe ₂ O ₃ had a mobile charge density about 4 times greater than that of NiOOH. Therefore, even if the film area of Fe ₂ O ₃ is reduced to ¼, it is possible to obtain a similar mobile charge density. Since Fe ₂ O ₃ is less expensive than IrO _x , it can be suitably used as a material for the auxiliary electrode.

(Example 3)
A light control device using a WO ₃ thin film as the first EC electrode, a NiOOH thin film as the second EC electrode, and Fe ₂ O ₃ as the auxiliary electrode was manufactured.

  FIG. 12 shows a photograph of the light control device. As the electrolyte material, a material obtained by dispersing sulfonated tetrafluoroethylene (trade name: Nafion) in a mixed solution of water and propyl alcohol was used.

Sulfonated tetrafluoroethylene is a proton-conductive electrolyte, and the WO ₃ thin film, NiOOH thin film, and Fe ₂ O ₃ thin film used as electrodes are respectively
The redox reaction of Here, the oxidation state WO ₃ is transparent, the reduction state H _x WO ₃ is blue, the oxidation state NiOOH is brown, and the reduction state Ni (OH) ₂ is transparent. Fe ₂ O ₃ and Fe ₃ O ₄ are yellow to brown and do not cause a significant color change.

When a positive voltage is applied to the first EC electrode (WO ₃ thin film) and a negative voltage is applied to the auxiliary electrode (Fe ₂ O ₃ ), the first EC electrode is decolored, and a negative voltage is applied to the second EC electrode (NiOOH thin film). When a positive voltage is applied to (Fe ₂ O ₃ ), the second EC electrode is decolored, both the first EC electrode and the second EC electrode are in a transparent state, and both visible light and near infrared light are transmitted (FIG. 12A). By applying a negative voltage to the first EC electrode and a positive voltage to the auxiliary electrode, the first EC electrode (WO ₃ thin film) is colored blue, the near infrared ray is blocked, and visible light is transmitted (FIG. 12B). )). On the other hand, by applying a positive voltage to the second EC electrode and a negative voltage to the auxiliary electrode, the second EC electrode (NiOOH thin film) is colored brown, the visible light is blocked, and the near infrared light is transmitted (FIG. 12 ( c)). By applying a negative voltage to the first EC electrode, a positive voltage to the auxiliary electrode, and further applying a positive voltage to the second EC electrode and a negative voltage to the auxiliary electrode, the first EC electrode (WO ₃ thin film) and the second EC Both electrodes (NiOOH thin film) are colored, and both near infrared rays and visible light are blocked (FIG. 12 (d)). Thus, by applying a voltage between the first EC electrode and the auxiliary electrode, the light transmittance in the near infrared region is controlled, and by applying a voltage between the second EC electrode and the auxiliary electrode, The light transmittance in the visible light region was controlled. From the above, it has been shown that the light transmittance in the near-infrared region and the light transmittance in the visible light region are independently controlled by the light control device of the present embodiment.

Claims (12)

A first electrochromic electrode;
A second electrochromic electrode provided opposite to the first electrochromic electrode;
An electrolyte layer disposed between the first electrochromic electrode and the second electrochromic electrode;
An auxiliary electrode electrically connected to the first electrochromic electrode and the second electrochromic electrode via the electrolyte layer;
With
By applying a voltage between the first electrochromic electrode and the auxiliary electrode, the light transmittance in the near infrared region is controlled,
By applying a voltage between the second electrochromic electrode and the auxiliary electrode, the light transmittance in the visible light region is controlled,
The light transmittance in the near infrared region and the light transmittance in the visible light region are each controlled independently.
A light control device characterized by that. In the first electrochromic electrode, in the low transmittance state, the absorption in the near infrared region is larger than the absorption in the visible light region,
In the second electrochromic electrode, in the low transmittance state, the absorption in the visible light region is larger than the absorption in the near infrared region,
The light control device according to claim 1. The first electrochromic electrode includes a thin film selected from the group consisting of tungsten oxide, molybdenum oxide, titanium oxide, and composite oxides thereof.
The light control device according to claim 1 or 2, wherein The thickness of the thin film of the first electrochromic electrode is not less than 50 nm and not more than 1 μm.
The light control device according to claim 3. The second electrochromic electrode includes a thin film selected from the group consisting of a composite oxide containing nickel oxyhydroxide, nickel hydroxide, nickel oxide and nickel oxide,
The light control device according to claim 1, wherein the light control device is a light control device. The film thickness of the thin film of the second electrochromic electrode is not less than 50 nm and not more than 1 μm.
The light control device according to claim 5. The auxiliary electrode is selected from the group consisting of iron oxyhydroxide, iron hydroxide, iron oxide, iridium oxide, and complex oxides thereof.
The light control device according to claim 1, wherein the light control device is a light control device. The charge capacity of the auxiliary electrode is larger than the charge capacity of the first electrochromic electrode and the second electrochromic electrode,
The light control device according to any one of claims 1 to 7, wherein   A light control window comprising the light control device according to claim 1. The first electrochromic electrode and the second electrochromic electrode are installed in a central portion of a window surface,
The auxiliary electrode is installed in the window frame part,
The light control window according to claim 9. The first electrochromic electrode and the second electrochromic electrode are installed in a central portion of a window surface,
The auxiliary electrode is disposed in the electrolyte layer;
The light control window according to claim 9. By applying a voltage between the first electrochromic electrode and the auxiliary electrode, the light transmittance in the near infrared region is controlled,
By applying a voltage between the second electrochromic electrode provided opposite to the first electrochromic electrode and the auxiliary electrode, the light transmittance in the visible light region is controlled,
The auxiliary electrode is electrically connected to the first electrochromic electrode and the second electrochromic electrode via an electrolyte layer disposed between the first electrochromic electrode and the second electrochromic electrode. Connected,
The light transmittance in the near infrared region and the light transmittance in the visible light region are each controlled independently.
The light control method characterized by this.