WO2020137328A1

WO2020137328A1 - Electrochromic transistor, electronic curtain, information display/storage device, and anti-glare mirror

Info

Publication number: WO2020137328A1
Application number: PCT/JP2019/046479
Authority: WO
Inventors: 太田　裕道; 尚記小野里
Original assignee: 国立大学法人北海道大学
Priority date: 2018-12-27
Filing date: 2019-11-28
Publication date: 2020-07-02
Also published as: JP2020106626A

Abstract

An electrochromic transistor has: a gate electrode 17 comprising an active layer 15 including an electrolyte containing an electrochromic resin and water, and a transparent electroconductive film 12 and a transparent electroconductive film provided with the active layer 15 therebetween; and a source electrode 13 and a drain electrode 14. From a state in which the electrochromic resin of the active layer 15 is a colorless and transparent insulator, a positive gate voltage is applied to the gate electrode 17, and by electrolysis of the water contained by the electrolyte of the active layer 15, protons are generated, and the electrochromic resin is protonated and converted to a black metal. A negative gate voltage is applied to the gate electrode 17, and protons are thereby moved in the reverse direction, and the electrochromic material is deprotonated and returned to the colorless and transparent insulator state.

Description

Electrochromic transistor, electronic curtain, information display storage device and anti-glare mirror

The present invention relates to an electrochromic transistor, an electronic curtain, an information display storage device, and an antiglare mirror, and relates to, for example, antiglare windows of aircrafts, automobiles, buildings, etc., or displaying/storing information on these windows. It is suitable for application to antiglare of automobile rearview mirrors.

Electrochromism is a phenomenon in which the color of a material is reversibly changed from colorless transparent to black by electrochemically oxidizing and reducing a substance called electrochromic material that contains metal ions. Electrochromism can be used as an electronic curtain for passenger planes and residential windows because the color of the glass can be switched from colorless transparent to black and the transmittance of outside light can be adjusted. It has begun to be applied as an anti-glare mirror to reduce the glare of the headlights of the following vehicles reflected in the mirror. Its market size is 1.5 billion dollars in 2016 (about 160 billion yen) and 4 billion dollars in 2023 ( It is expected to exceed JPY 430 billion).

Tungsten oxide (WO ₃ ), which has been known as an electrochromic material since the 1970s, is an insulator that is colorless and transparent and does not conduct electricity. However, it is a metal that is black and conducts electricity well due to electrochemical inclusion of hydrogen. The electrochromism of returning to the original colorless and transparent insulator by drawing out hydrogen is shown.

The present inventors have recently applied a thin film transistor structure to an electrochromic material to display and store information with a color change of colorless transparent ⇔ black, and at the same time store electricity ⇔ not pass (= electronic information). , Succeeded in developing a new readable three-terminal element (hereinafter referred to as “electrochromic transistor”) (see Non-Patent Document 1). A new information display storage device can be realized by using this electrochromic transistor. In this electrochromic transistor, a transparent source electrode and a drain electrode made of a tin (Sn)-doped indium oxide (ITO) film are formed on a glass substrate, and the transparent source electrode and the drain electrode are formed on the glass substrate so as to extend over these source electrode and drain electrode. A WO ₃ layer serving as an active layer is formed on the WO ₃ layer, and a water-containing cement thin film made of calcium aluminate having a large number of nanopores is formed as a gate insulating film on the WO ₃ layer. It has a structure in which a transparent gate electrode made of an ITO film is sequentially formed. In the information display storage device using this electrochromic transistor, the state of the insulator in which the WO ₃ layer does not conduct electricity is information “0”, and the state of the metal through which electricity easily passes is information “1”. It is possible to electrically store and read the information "0" and "1" in addition to the captured color change information "transparent" and "black".

This electrochromic transistor or information display memory device can be manufactured at low cost at room temperature, and it is easy to increase the area.

In the electrochromic transistor described in Non-Patent Document 1, in order to protonate the WO ₃ layer of the active layer (WO ₃ →H _x WO ₃ ), it is necessary to apply +3 V to the gate electrode with respect to the source electrode for 300 seconds. For protonation (H _x WO ₃ →WO ₃ ), it is necessary to apply −3 V to the gate electrode with respect to the source electrode for 100 seconds. That is, at a practical operation switching voltage of 3V, the time required for switching is about 100 to 300 seconds. Therefore, it has been desired to reduce the time required for switching.

Therefore, the problem to be solved by the present invention is that the time required for switching is significantly shortened as compared with the electrochromic transistor described in Non-Patent Document 1 even with a practical operating switching voltage of 3V. PROBLEM TO BE SOLVED: To provide an electrochromic transistor, a high-performance electron curtain using the electrochromic transistor, a high-performance information display storage device using the electrochromic transistor, and a high-performance antiglare mirror using the electrochromic transistor. Is.

In order to solve the above problems, the present invention provides
An active layer comprising at least an electrochromic material and an electrolyte containing water;
It is an electrochromic transistor having a first transparent conductive film and a second transparent conductive film provided so as to sandwich the active layer.

Here, the electrochromic transistor is a three-terminal element having a thin film transistor structure that uses an electrochromic material for an active layer and has a source electrode, a drain electrode, and a gate electrode. The active layer may have any form as long as it contains at least an electrochromic material and an electrolyte containing water, and is designed as necessary. Typically, the active layer has a structure in which a first layer made of an electrochromic material and a second layer made of an electrolyte are laminated on each other. At least a part or the whole of the active layer may have a structure in which a fine particle electrochromic material and a fine particle electrolyte are mixed. The active layer is provided so as to make electrical contact with the source electrode and the drain electrode.

One of the first transparent conductive film and the second transparent conductive film constitutes a gate electrode, the other is integrated with the active layer, and the sheet resistance of the channel is reduced by making electrical contact with the source electrode and the drain electrode. Contribute to. The first transparent conductive film and the second transparent conductive film are made of, for example, a transparent conductive oxide (TCO), a transparent metal such as ultra-thin gold (Au), or the like, and are selected as necessary. The transparent conductive oxide is generally an oxide containing at least one metal selected from the group consisting of indium (In), zinc (Zn), gallium (Ga) and tin (Sn). .. Specifically, the transparent conductive oxide is, for example, In ₂ O ₃ (ITO) doped with tin (Sn), ZnO doped with gallium (Ga), aluminum (Al), or the like, and doped with fluorine (F). Tin oxide (SnO ₂ ) and the like. The electric conductivity of the first transparent conductive film and the second transparent conductive film is generally 0.01 S/cm or more and 100000 S/cm or less.

When the active layer has a structure in which the first layer and the second layer are laminated as described above, the thickness and electric conductivity (or conductivity) of the first layer, the first transparent conductive film The thickness and electric conductivity (or electric conductivity) of the second transparent conductive film located on the first layer side are selected as follows. That is, the thickness of the first layer is t ₁ , the electrical conductivity is σ ₁ , and the thickness of _one of the first transparent conductive film and the second transparent conductive film located on the side of the first layer is t _2. , And the electrical conductivity is σ ₂ . With respect to the target electrical on/off ratio (ratio of the sheet resistance of the on channel to the sheet resistance of the on channel) of this electrochromic transistor, Log (on/off ratio)=Log(t ₁ / t ₁ , σ ₁ , t ₂ , and σ ₂ are selected so that t ₂ )+Log(σ ₁ /σ ₂ ) holds.

The electrochromic material may be an inorganic material, an organic material, or an organic-inorganic composite material, and is selected as necessary. The inorganic electrochromic material is typically an oxide electro containing at least one metal selected from the group consisting of tungsten (W), vanadium (V), niobium (Nb) and titanium (Ti). Examples include, but are not limited to, chromic materials. The oxide electrochromic material is, in one typical example, an amorphous or crystalline simple oxide represented by the composition formula AO _x (A is tungsten, vanadium, niobium or titanium, and x is in the range of 1 to 3). Is. A representative example of AO ₃ is WO ₃ . Examples of the organic electrochromic material include, but are not limited to, various conductive polymer compounds, viologen compounds, leuco dye compounds, and terephthalic acid compounds.

The electrolyte is not particularly limited as long as it contains water, and is selected as necessary. The electrolyte is preferably, but not limited to, an oxide dielectric containing 1% or more and 50% or less by volume of water. Oxide dielectrics are generally various metal oxides (including complex oxides and glasses) that can be made porous and contain water. Specific examples of such metal oxides include TaO _x , NbO _x , ZrO _x , HfO _x , AlO _x , SiO _x , and GaO _x . As the electrolyte, water-containing cement composed of calcium aluminate having a large number of nanopores described in Non-Patent Document 1 may be used.

Typically, one of the first transparent conductive film and the second transparent conductive film is provided on the transparent substrate. The transparent substrate is, for example, a transparent glass substrate or a transparent plastic substrate. The transparent substrate is configured flexibly as needed. Examples of the transparent plastic constituting the transparent plastic substrate include polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polystyrene, polyethylene, polypropylene, polyphenylene sulfide, polyvinylidene fluoride, acetyl cellulose, brominated phenoxy, aramids, polyimides, polystyrene. , Polyarylates, polysulfones, polyolefins and the like can be used.

Further, the present invention is
A transparent substrate,
Having one or more electrochromic transistors provided on the transparent substrate,
The electrochromic transistor is
An active layer comprising at least an electrochromic material and an electrolyte containing water;
It is an electronic curtain having a first transparent conductive film and a second transparent conductive film provided so as to sandwich the active layer.

Further, the present invention is
A transparent substrate,
Having a plurality of electrochromic transistors provided on the transparent substrate,
The electrochromic transistor is
An active layer comprising at least an electrochromic material and an electrolyte containing water;
An information display storage device having a first transparent conductive film and a second transparent conductive film provided so as to sandwich the active layer.

The information display storage device displays color information "colorless and transparent" and "black" when the electrochromic transistor is off and on, and electrical conduction information "0" and "1" when the electrochromic transistor is off and on. It can be stored and read. The arrangement of the electrochromic transistors on the transparent substrate is selected as necessary, but typically, a plurality of electrochromic transistors are arranged in a matrix.

Further, the present invention is
A transparent substrate provided on the surface of the mirror,
Having one or more electrochromic transistors provided on the transparent substrate,
The electrochromic transistor is
An active layer comprising at least an electrochromic material and an electrolyte containing water;
It is an antiglare mirror having a first transparent conductive film and a second transparent conductive film provided so as to sandwich the active layer.

The use of the anti-glare mirror is not particularly limited, but it is, for example, an automobile rearview mirror.

In each of the inventions of the electronic curtain, the information display storage device, and the antiglare mirror described above, what has been described in connection with the invention of the electrochromic transistor is established unless it is contrary to the property.

According to the present invention, since the transparent conductive film is provided in contact with the active layer containing at least the electrochromic material and the electrolyte containing water, the effective sheet resistance of the channel can be significantly reduced. Enables a high performance electrochromic transistor with an active layer that is colorless and transparent and has an extremely high electrical and optical on/off ratio between an insulator state and a black state and a metal state and a switching speed. be able to. By using this high-performance electrochromic transistor, it is possible to realize an electronic curtain capable of controlling light transmission at high speed, and at the same time, information display capable of displaying/storing/reading information at high speed. A storage device can be realized. Furthermore, by using this high-performance electrochromic transistor, it is possible to realize an antiglare mirror capable of effective antiglare even at night.

1 is a sectional view showing an electrochromic transistor according to a first embodiment of the present invention. 1 is a plan view showing an electrochromic transistor according to a first embodiment of the present invention. FIG. 3 is a sectional view showing a first example of a structure of an active layer of the electrochromic transistor according to the first embodiment of the present invention. FIG. 6 is a sectional view showing a second example of the structure of the active layer of the electrochromic transistor according to the first embodiment of the present invention. FIG. 3 is a schematic diagram showing the relationship between the electrical on/off ratio and the thickness ratio t ₁ /t ₂ of the electrochromic transistor according to the first embodiment of the present invention. FIG. 3 is a cross-sectional view showing an electrochromic transistor according to an example. FIG. 6 is a plan view showing an electrochromic transistor according to an example. 8 is a drawing-substituting photograph showing an electrochromic transistor according to an example. FIG. 6 is a cross-sectional view showing an electrochromic transistor according to a comparative example. FIG. 6 is a schematic diagram showing a time change of sheet resistance due to protonation of an electrochromic transistor according to an example and an electrochromic transistor according to a comparative example. FIG. 6 is a schematic diagram showing a change over time in sheet resistance with deprotonation of an electrochromic transistor according to an example and an electrochromic transistor according to a comparative example. FIG. 6 is a schematic diagram showing transmission spectra of an electrochromic transistor according to an example and an electrochromic transistor according to a comparative example in an initial state and a state in which +3V is applied to a gate electrode. It is a top view which shows the electronic curtain by the 2nd Embodiment of this invention. It is a front view which shows the example which applied the electronic curtain by the 2nd Embodiment of this invention to the window of an aircraft. It is a front view which shows the example which applied the electronic curtain by the 2nd Embodiment of this invention to the window of a building. It is a top view which shows the information display memory|storage device by the 3rd Embodiment of this invention. It is a top view which shows an example which displays and memorize|stores information in the information display memory|storage device by the 3rd Embodiment of this invention.

Hereinafter, modes for carrying out the invention (hereinafter, referred to as “embodiments”) will be described with reference to the drawings.

<First Embodiment>
[Electrochromic transistor]
1 and 2 show an electrochromic transistor according to a first embodiment, FIG. 1 is a sectional view, and FIG. 2 is a plan view.

As shown in FIGS. 1 and 2, in this electrochromic transistor, a transparent conductive film 12 is provided on a transparent substrate 11. A transparent source electrode 13 and a transparent drain electrode 14 are provided on the transparent conductive film 12 so as to face each other. An active layer 15 is provided on the transparent conductive film 12 so that both ends thereof are electrically contacted over the source electrode 13 and the drain electrode 14. The active layer 15 contains at least an electrochromic material and an electrolyte containing water, and may contain a material other than the electrochromic material and the electrolyte as necessary, but typically, the electrochromic material and the electrolyte. It consists of and. The electrochromic material forming the active layer 15 is a colorless and transparent insulator when it is not protonated, and in the electrochromic transistor, the active layer 15 becomes non-conductive and a current flows between the source electrode 13 and the drain electrode 14. However, when the electrochromic material is protonated, it changes to a black metal. At that time, in the electrochromic transistor, the active layer 15 becomes conductive and a current flows between the source electrode 13 and the drain electrode 14 to turn it on. Become. An absorption layer 16 that also serves as a gate insulating film is provided on the active layer 15. A gate electrode 17 made of a transparent conductive film is provided on the absorption layer 16. Therefore, this electrochromic transistor has a structure in which the active layer 15 is sandwiched between the transparent conductive film and the transparent conductive film 12 which form the gate electrode 17.

The transparent substrate 11 is a transparent glass substrate or a transparent plastic substrate made of the transparent plastic already mentioned. The transparent substrate 11 is configured flexibly as needed. The thickness and material of the transparent substrate 11 are selected as needed within a range in which required transparency and strength can be obtained. In FIG. 2, the planar shape of the transparent substrate 11 is rectangular, but the planar shape of the transparent substrate 11 is selected as necessary depending on the application of the electrochromic transistor and other polygons (triangle, pentagon, hexagon, etc.). Besides, it may have a circular shape, an elliptical shape, or a shape obtained by modifying these shapes.

The transparent conductive film forming the transparent conductive film 12 and the gate electrode 17 is made of, for example, various kinds of transparent conductive oxide (TCO) or an ultrathin Au film. The thickness and electric conductivity of the transparent conductive film 12 will be described later.

The source electrode 13 and the drain electrode 14 are made of, for example, a transparent conductive film such as various transparent conductive oxides (TCO) or an ultrathin Au film, and are selected as needed. The planar shapes of the source electrode 13 and the drain electrode 14 are generally rectangular, but are not limited to this.

The electrochromic material and the electrolyte forming the active layer 15 are selected from those already mentioned as needed. The electrolyte consists of an oxide dielectric containing water and is transparent. The active layer 15 has a structure in which a first layer made of an electrochromic material and a second layer made of an electrolyte are laminated on each other, and at least a part or all of the active layer 15 is a fine particle electrochromic material and fine particles. There is a case where it has a mixed structure with a solid electrolyte. An example of the former is shown in FIG. 3 and an example of the latter is shown in FIG. As shown in FIG. 3, in this example, the lower layer of the active layer 15 is a first layer 15a made of an electrochromic material and the upper layer is a second layer 15b made of an electrolyte. Another example shown in FIG. 4 has a structure in which a large number of fine particle electrochromic materials 15c and fine particle electrolytes 15d are mixed. In FIG. 4, the fine particle electrochromic material 15c is drawn larger than the fine particle electrolyte 15d in order to distinguish between the fine particle electrochromic material 15c and the fine particle electrolyte 15d. Is not limited to this, and is selected as needed. Further, in FIG. 4, the fine particle-shaped electrochromic material 15c and the fine particle-shaped electrolyte 15d are drawn in a spherical shape, but the shape is not limited to this, and other shapes may be used. The planar shape of the active layer 15 is generally rectangular, but is not limited to this and may be selected as necessary.

The absorption layer 16 plays a role of absorbing OH ⁻ released from the active layer 15 during the operation of the electrochromic transistor. The absorption layer 16 is made of, for example, NiO, but is not limited to this. The thickness of the absorption layer 16 is not particularly limited and is selected as necessary, but is generally 10 nm to 30 nm. The absorption layer 16 can be omitted if necessary.

Like the source electrode 13 and the drain electrode 14, the gate electrode 17 is made of, for example, a transparent conductive film such as various transparent conductive oxides (TCO) or an ultrathin Au film, and is selected as necessary. The planar shape of the gate electrode 17 is generally rectangular, but is not limited to this. The thickness of the gate electrode 17 is not particularly limited and is selected as necessary, but is generally 10 nm to 30 nm.

When the active layer 15 has a two-layer structure including a first layer 15a made of an electrochromic material and a second layer 15b made of an electrolyte as shown in FIG. 3, the thickness t of the first layer 15a is t. _{1, the} electric conductivity σ ₁ , the thickness t ₂ of the transparent conductive film 12 and the electric conductivity σ ₂ are selected as follows. That is, in FIG. 5, the vertical axis represents the electrical on/off ratio of the electrochromic transistor, and the horizontal axis represents the thickness ratio t ₁ /t ₂ . In FIG. 5, σ ₁ is fixed at 7,000 S/cm (assuming that the first layer 15a is the WO ₃ layer), and σ ₂ is a parameter, Log (on/off ratio)=Log(t ₁ /t ₂ )+Log(σ ₁ /σ ₂ ). In FIG. 5, σ ₂ was changed to 0.01 S/cm, 0.1 S/cm, 1 S/cm, 10 S/cm, 100 S/cm, and 1000 S/cm to draw a straight line. t ₁ , t ₂ , σ ₁ , and σ ₂ are Log (on/off ratio)=Log(t ₁ /t ₂ )+Log(σ ₁ /σ ₂ ) with respect to the target electrical on/off ratio. Is selected so that For example, if σ ₂ =1000 S/cm, it can be understood that t ₁ /t ₂ should be set to about 2 when the target electrical on/off ratio is 10.

When the active layer 15 has a structure in which a large number of fine particle electrochromic materials 15c and fine particle electrolytes 15d are mixed as shown in FIG. 4, the total mass of the electrochromic material 15c contained in the active layer 15 is By using the thickness (equivalent thickness) converted to the thickness of the first layer 15a as t ₂ , the same handling as above can be approximately performed.

[Operation of electrochromic transistor]
The electrochromic material of the active layer 15 is initially not protonated and is assumed to be a colorless and transparent insulator. In this state, the active layer 15 is not conductive and no current flows between the source electrode 13 and the drain electrode 14. A gate voltage V _g necessary for electrolysis of water described below is applied between the source electrode 13 and the gate electrode 17. Generally, the source electrode 13 is grounded. When a positive voltage is applied as the gate voltage V _g , an electric field is applied from the gate electrode 17 to the transparent conductive film 12 in the thickness direction of the active layer 15. By this electric field, water in the electrolyte contained in the active layer 15 is electrolyzed to generate protons (H ⁺ ) and hydroxide ions (OH ⁻ ). Of these, H ⁺ is taken into the electrochromic material of the active layer 15 by the electric field and protonated, and OH ⁻ penetrates the active layer 15 by the electric field and is taken into the absorption layer 16. When the electrochromic material of the active layer 15 is protonated, the electrochromic material becomes a black metal. At this time, the active layer 15 becomes conductive, and a current flows between the source electrode 13 and the drain electrode 14.

Next, when a negative voltage is applied as the gate voltage V _g , an electric field is applied in the thickness direction of the active layer 15 in the direction from the transparent conductive film 12 to the gate electrode 17. By this electric field, protons are extracted from the electrochromic material of the active layer 15 to cause deprotonation, and OH ⁻ is extracted from the absorption layer 16. Thus, H ⁺ extracted from the electrochromic material and OH ⁻ extracted from the absorption layer 16 generate water, which is taken into the electrolyte in the active layer 15. When deprotonation of the electrochromic material of the active layer 15 occurs, the electrochromic material returns to a colorless and transparent insulator. At this time, the active layer 15 does not conduct, and no current flows between the source electrode 13 and the drain electrode 14.

[Method for manufacturing electrochromic transistor]
As shown in FIG. 1, first, after forming the transparent conductive film 12 on the transparent substrate 11, the source electrode 13 and the drain electrode 14 made of the transparent conductive film are formed thereon. These transparent conductive films can be formed by a conventionally known method and are selected as necessary, and for example, a pulse laser deposition (PLD) method, a vacuum evaporation method or the like is used. The source electrode 13 and the drain electrode 14 can be formed by selectively depositing a transparent conductor using a metal mask.

Next, the active layer 15 is formed on the transparent conductive film 12 so that both ends thereof straddle the source electrode 13 and the drain electrode 14. When the active layer 15 is composed of the first layer 15a and the second layer 15b as shown in FIG. 3, the first layer 15a and the second layer 15b are sequentially formed. The first layer 15a and the second layer 15b can be formed by a conventionally known method and are selected according to need. For example, a PLD method using a metal mask, a vacuum deposition method, or the like is used. .. When the active layer 15 is composed of the fine particle electrochromic material 15c and the fine particle electrolyte 15d as shown in FIG. 4, the fine particle electrochromic material 15c and the fine particle electrolyte 15d are prepared in advance, and these are mixed with water or the like. A paste-like dispersion liquid uniformly dispersed in the solvent is prepared, and the dispersion liquid is applied or printed on the transparent conductive film 12 so as to extend over the source electrode 13 and the drain electrode 14. There is no particular limitation on the coating method or printing method of the dispersion liquid, and a conventionally known method can be used. Specifically, as a coating method, for example, a dipping method, a spray method, a wire bar method, a spin coating method, a roller coating method, a blade coating method, a gravure coating method, or the like can be used. As a printing method, a letterpress printing method, an offset printing method, a gravure printing method, an intaglio printing method, a rubber plate printing method, a screen printing method or the like can be used. In this way, the fine particle electrochromic material 15c and the fine particle electrolyte 15d are applied or printed on the transparent conductive film 12, the source electrode 13 and the drain electrode 14, and then the solvent is evaporated and removed. If necessary, firing may be performed in order to improve the mechanical strength of the active layer 15 and improve the adhesion to the transparent conductive film 12 and the like. The firing temperature is selected to be lower than the heat resistant temperature of the transparent substrate 11, and is generally 40 to 200°C.

Next, the absorption layer 16 is formed on the active layer 15. The absorption layer 16 can be formed by a conventionally known method and is selected according to need. For example, a PLD method, a vacuum vapor deposition method or the like is used.

Next, the gate electrode 17 made of a transparent conductive film is formed on the absorption layer 16. The gate electrode 17 can be formed by a conventionally known method and is selected according to need. For example, a PLD method, a vacuum deposition method or the like is used. The gate electrode 17 can be formed by selectively depositing a transparent conductor using a metal mask.

By the above, the target electrochromic transistor is manufactured.

An example will be described.
(Example)
The electrochromic transistor shown in FIGS. 6 and 7 was produced. FIG. 8 shows an optical microscope photograph of this electrochromic transistor. As the transparent substrate 11, a glass substrate having a thickness of 0.7 mm and a size of 10 mm×10 mm was used. As the transparent conductive film 12, a ZnO film having a thickness of 30 nm (electric conductivity is 30 S/cm) was formed. An ITO film (electric conductivity: 2000 S/cm) having a thickness of 20 nm was formed as the source electrode 13 and the drain electrode 14. An active layer 15 having a two-layer structure composed of a first layer 15a and a second layer 15b is used, the first layer 15a is a WO ₃ layer having a thickness of 100 nm, and the second layer 15b is a layer having a thickness of 250 nm. A TaO _x layer was formed. As the absorption layer 16, a NiO layer having a thickness of 20 nm was formed. An ITO film having a thickness of 20 nm was formed as the gate electrode 17. These ZnO film, ITO film, WO ₃ layer, TaO _x layer and NiO layer were formed by the PLD method at room temperature. The distance between the source electrode 13 and the drain electrode 14, that is, the channel length is 800 μm, which is the same as the length of the gate electrode 17 in the channel length direction, that is, the gate length. The length of the active layer 15 in the direction orthogonal to the channel length direction, that is, the channel width is 400 μm.

(Comparative example)
As a comparative example, the electrochromic transistor described in FIG. 1 of Non-Patent Document 1 was manufactured. FIG. 9 shows a sectional view of this electrochromic transistor. The plan view of this electrochromic transistor is similar to that of FIG. In this electrochromic transistor, the ZnO film as the transparent conductive film 12 is not formed, the WO ₃ layer has a thickness of 80 nm, and the cement thin film CAN having a thickness of 300 nm is used instead of the TaO _x layer shown in FIG. Different from the electrochromic transistor according to the embodiment, the formation of (calcium aluminate having a large number of holes with a diameter of about 10 nm (chemical composition 12CaO.7Al ₂ O ₃ , the main component of alumina cement)) is different from that of the electrochromic transistor according to the embodiment. And the size of each part is the same.

(Evaluation results)
FIG. 10 shows the retention time (Retention time) when the first layer 15a of the active layer 15 is protonated by applying +3 V as the gate voltage V _g to the gate electrode 17 of the electrochromic transistor according to the example and the comparative example. ) shows the measurement results of the change in the sheet resistance R _s with respect to t. To measure the sheet resistance R _s , as shown in FIG. 7, the sheet resistance measuring electrodes E ₁ to E ₄ are formed on the WO ₃ layer (first layer 15a made of an electrochromic material) and the ZnO film (transparent conductive film 12). Were contacted with each other and the DC four-terminal method was used. The applied current was about 100 μA. The inset in FIG. 10 is an enlarged view of t=0 to 10 (sec). FIG. 11 shows the retention time t when the first layer 15a of the active layer 15 is deprotonated by applying −3 V as the gate voltage V _g to the gate electrode 17 of the electrochromic transistor according to the example and the comparative example. shows the results of measuring the change in the sheet resistance R _s for. The sheet resistance R _s was measured in the same manner as above using the sheet resistance measuring electrodes E ₁ to E ₄ . The inset in FIG. 11 is an enlarged view of t=0 to 10 (sec). As is clear from FIG. 10, in the electrochromic transistor according to the comparative example, it takes about 300 seconds to complete the protonation, whereas in the electrochromic transistor according to the example, the protonation is completed in about 1 second. Further, as is apparent from FIG. 11, in the electrochromic transistor according to the comparative example, it takes about 100 seconds to complete deprotonation, whereas in the electrochromic transistor according to the example, deprotonation is completed in about 1 second. ing. That is, the electrochromic transistor according to the example has a switching time significantly shortened to about 1/300 as compared with the electrochromic transistor according to the comparative example.

Figure 12 shows the results of measurement of the transmission spectrum of the entire transistor while applying a + 3V as examples and the initial state (state prior to application of the gate voltage V _g) of the electrochromic transistor according to the comparative example and the gate voltage V _g. In the electrochromic transistor according to the example, the application time of the gate voltage V _g is 1 second, and in the electrochromic transistor according to the comparative example, the application time of the gate voltage V _g is 20 seconds. From FIG. 12, the light transmittance for a wavelength of about 570 nm is 67% when the electrochromic transistor according to the embodiment is off, 28% when the on/off ratio is about 40% when the on, and 71% when the electrochromic transistor according to the comparative example is off. The on/off ratio is about 10% at 63% when turned on. That is, the electrochromic transistor according to the example has an optical on/off ratio improved by about 4 times as compared with the electrochromic transistor according to the comparative example.

As described above, according to the first embodiment, the same advantages as those of the electrochromic transistor described in Non-Patent Document 1 can be obtained, and the transparent conductive film is provided between the transparent substrate 11 and the active layer 15. By providing the film 12, the electrical on/off ratio, which is the ratio of the sheet resistance of the on-channel to the sheet resistance of the off-channel, can be significantly improved, and the off-color is colorless. The optical on/off ratio, which is the ratio of the light transmittance in the black state when turned on to the light transmittance in the transparent state, can be made sufficiently high, and even at a practical operating switching voltage of 3 V, it is extremely high. It is possible to realize a high-performance electrochromic transistor capable of switching at high speed. This electrochromic transistor can be manufactured inexpensively at room temperature and can easily be made large in area. This electrochromic transistor is an electronic curtain used for windows of moving objects such as various aircraft (passenger planes, transport planes, helicopters, etc.) and various automobiles (including electric vehicles and self-driving cars), automobile rearview mirrors. In addition to an anti-glare mirror used for the above, an information display storage device for displaying and storing information in windows, etc., it can be applied to a touch panel and the like.

<Second Embodiment>
[Electronic curtain]
FIG. 13 shows an electronic curtain according to the second embodiment. This electronic curtain uses the electrochromic transistor according to the first embodiment as an optical shutter.

This electronic curtain has one or a plurality of electrochromic transistors according to the first embodiment formed on a transparent substrate 11. The electrochromic transistor does not necessarily have to be formed on the entire surface of the transparent substrate 11, and may be formed on a portion of the transparent substrate 11 where light transmission is desired to be controlled. When it is desired to control light transmission over substantially the entire surface of the transparent substrate 11, the active layer 15 of a single electrochromic transistor is formed so that the area of the transparent substrate 11 and the total area of the active layer 15 are substantially the same. Or, a plurality of electrochromic transistors are spread over the entire surface of the glass plate 110. FIG. 13 shows, as an example, a case where four electrochromic transistors T ₁ to T ₄ are formed in close contact with each other, but the present invention is not limited to this. The source wiring, the drain wiring, and the gate wiring of the electrochromic transistor can be formed on the transparent substrate 11 using various conductive films such as a transparent conductive film, and can be led out to the outer peripheral portion of the transparent substrate 11. In this way, the power source can be connected to the end portions of the source wiring, the drain wiring, and the gate wiring that are drawn to the outer peripheral portion of the transparent substrate 11.

This electronic curtain can be basically installed in any part as long as it is a part where it is desired to control the transmission of light. Specifically, for example, various types of windows such as aircraft windows, buildings, houses, etc. It can be applied to windows of buildings. FIG. 14 shows an example in which the electronic curtain 200 is applied to the window 110 provided on the wall surface 100 inside the aircraft, and FIG. 15 shows an example in which the electronic curtain 200 is applied to the window 400 on the wall 300 of the building.

According to the second embodiment, the light transmittance can be controlled at high speed, antiglare can be achieved when applied to a window, and high-performance electronic that can be manufactured at low cost. The curtain can be realized.

<Third Embodiment>
[Information display storage device]
FIG. 16 shows an information display storage device according to the third embodiment. This information display storage device uses the electrochromic transistor according to the first embodiment.

As shown in FIG. 16, in this information display storage device, the electrochromic transistors according to the first embodiment are arranged on the transparent substrate 11 in a matrix of n rows and m columns, n×m in total, vertically and horizontally. It is a thing. Each electrochromic transistor is designated as T _ij (i=1 to n, j=1 to m). n and m are appropriately selected depending on the application of the information display storage device. Although FIG. 16 shows the case where n=18 and m=22, the present invention is not limited to this. These electrochromic transistors T _ij can be driven independently. The source wiring, the drain wiring, and the gate wiring of the electrochromic transistor T _ij can be formed in the same manner as the wiring of the pixel switching thin film transistor of the liquid crystal display, for example. These source wiring, drain wiring, and gate wiring can be formed on the transparent substrate 11 using various conductive films such as a transparent conductive film, and can be drawn out to the outer peripheral portion of the transparent substrate 11. In this way, the power source can be connected to the end portions of the source wiring, the drain wiring, and the gate wiring that are drawn to the outer peripheral portion of the transparent substrate 11.

[Operation of information display storage device]
The electrochromic transistor T _ij is driven according to the information to be displayed and stored in the information display storage device, the active layer 15 is colorless and transparent and the state of the insulator is “0” and the active layer 15 is black and the state of the metal is “. 1”. For example, as shown in FIG. 17, when the character “A” is displayed and stored as information, only the electrochromic transistor T _ij necessary for displaying the character “A” is driven, and the electrochromic of the active layer 15 is driven. The material turns black due to protonation. By doing so, the character "A" can be displayed and stored. When erasing the information of the character “A”, only the electrochromic transistor T _ij used for displaying the character “A” is driven to make it colorless and transparent by deprotonating the electrochromic material of the active layer 15.

According to the third embodiment, information can be displayed/stored/erased/read out at high speed on windows of various moving bodies such as airplanes and automobiles or windows of buildings, and the manufacturing cost is low. It is possible to realize a high performance information display storage device that can be realized.

Although the embodiments and examples of the present invention have been specifically described above, the present invention is not limited to the above-described embodiments and examples, and various modifications based on the technical idea of the present invention. Is possible.

For example, the numerical values, materials, configurations, arrangements, processes, etc. mentioned in the above-described embodiments and examples are merely examples, and different numerical values, materials, configurations, arrangements, processes, etc. may be used as necessary. May be.

11 transparent substrate 12 transparent conductive film 13 source electrode 14 drain electrode 15 active layer 15a first layer 15b second layer 15c fine particle electrochromic material 15d fine particle electrolyte 16 absorption layer 17 gate electrodes T ₁ to T ₄ , T _ij electrochromic transistor 100

wall surface

110, 400 window 200 electronic curtain 300 wall

Claims

An active layer comprising at least an electrochromic material and an electrolyte containing water;
An electrochromic transistor having a first transparent conductive film and a second transparent conductive film provided so as to sandwich the active layer.
The electrochromic transistor according to claim 1, wherein the active layer has a structure in which a first layer made of the electrochromic material and a second layer made of the electrolyte are laminated on each other.
The electrochromic transistor according to claim 1, wherein at least a part of the active layer has a structure in which the particulate electrochromic material and the particulate electrolyte are mixed.
The thickness of the first layer is t 1 , the electric conductivity is σ 1 , and the thickness of one of the first transparent conductive film and the second transparent conductive film located on the side of the first layer is When t 2 and the electrical conductivity are σ 2 , Log (on/off ratio)=Log(t 1 /t 2 )+Log(σ 1 /σ 2 ) with respect to the target electrical on/off ratio The electrochromic transistor according to claim 2 , wherein t 1 , σ 1 , t 2 and σ 2 are selected so that
The electrochromic transistor according to claim 1, wherein the electrochromic material is an oxide electrochromic material containing at least one metal selected from the group consisting of tungsten, vanadium, niobium, and titanium.
The oxide electrochromic material is an amorphous or crystalline simple oxide represented by the composition formula AO x (A is tungsten, vanadium, niobium or titanium, and x is in the range of 1 to 3). Electrochromic transistor.
The electrochromic transistor according to claim 1, wherein the electrolyte is an oxide dielectric containing water in a volume fraction of 1% or more and 50% or less.
The first transparent conductive film and the second transparent conductive film are made of a transparent conductive oxide containing at least one metal selected from the group consisting of indium, zinc, gallium and tin. Electrochromic transistor.
The electrochromic transistor according to claim 1, wherein the electrical conductivity of the first transparent conductive film and the second transparent conductive film is 0.01 S/cm or more and 100000 S/cm or less.
The electrochromic transistor according to claim 1, wherein one of the first transparent conductive film and the second transparent conductive film is provided on a transparent substrate.
A transparent substrate,
An active layer provided on the transparent substrate, containing at least an electrochromic material and an electrolyte containing water; and a first transparent conductive film and a second transparent conductive film provided so as to sandwich the active layer. An electronic curtain having at least one electrochromic transistor having.
A transparent substrate,
Having a plurality of electrochromic transistors provided on the transparent substrate,
The electrochromic transistor is
An active layer comprising at least an electrochromic material and an electrolyte containing water;
An information display storage device having a first transparent conductive film and a second transparent conductive film provided so as to sandwich the active layer.
A transparent substrate provided on the surface of the mirror,
Having one or more electrochromic transistors provided on the transparent substrate,
The electrochromic transistor is
An active layer comprising at least an electrochromic material and an electrolyte containing water;
An anti-glare mirror having a first transparent conductive film and a second transparent conductive film provided so as to sandwich the active layer.