JP4846296B2 - Electrochromic display element - Google Patents

Description

  The present invention relates to a technical field of an image display element using an electrochromic method. Specifically, the present invention relates to a technical field of an electrochromic image display device having a transparent transistor and a laminated structure.

  An EC display device having an electrochromic (hereinafter abbreviated as “EC”) display element has the greatest advantage that it has no viewing angle dependency and has a light receiving type and excellent visibility because a polarizing plate or the like is unnecessary. An EC display element has a simple structure and a large size because it functions as a display element if it has at least an electrolyte containing the EC material that is reversibly colored or decolored by an electrochemical redox reaction and a pair of electrodes. Is easy. Furthermore, by selecting the EC material, various color tones can be obtained, and the display state can be stopped just by blocking the movement of electrons and maintaining the redox state, so it has excellent memory characteristics and maintains its display state. However, since it has various advantages such as low power consumption because it does not require power, it is being applied in various fields.

  In recent years, for example, an EC display device in which the EC material is deposited on a pair of electrodes and a supporting salt and a solvent are sealed between the electrodes, or the EC material, the supporting salt and a solvent are sealed between a pair of electrodes. Various EC display devices such as an EC display device have been proposed (see, for example, Patent Documents 1 to 3).

  In particular, in an EC display device in which an EC dye is supported on a semiconductor nanoporous layer (see, for example, Patent Document 4), the EC dye contained in the electrolyte layer to every corner of the micropores of the semiconductor nanoporous layer. Efficiently penetrates, it is possible to increase the moving speed of ions involved in the color development / decoloring reaction, and the reaction speed is greatly improved. Further, since the electrode area can be increased, the coloring efficiency (to reach a desired coloring density faster with a lower applied voltage) is also improved by increasing the amount of the dye on the electrode.

  Here, in the multilayer display device, there are simple matrix driving and active matrix driving as a matrix driving method for each pixel. The simple matrix drive is required to have steepness in the VT (voltage-transmittance) characteristic. Active matrix driving includes an MIM system in which an active element is a diode and a TFT system in which an active element is a transistor. As a material of the TFT, an a-Si (amorphous silicon) TFT and a p-Si (polysilicon) TFT have been put into practical use.

Since these TFTs using silicon are opaque to visible light and cannot form a transparent circuit, the aperture ratio of the display pixel becomes small.
In addition, since amorphous silicon TFTs and polysilicon TFTs generate conductive carriers by irradiation with visible light, transistor characteristics deteriorate under high light irradiation. That is, a photo-induced current is generated by backlight irradiation, and the switching characteristics as a switching element are deteriorated. In order to prevent such deterioration, it is necessary to provide a light-shielding film (black matrix) on the TFT for cutting off the backlight light. As a result, the aperture ratio is decreased, and there is a problem that display performance is deteriorated.

  Such problems of the silicon field effect transistor can be solved in principle by using a semiconductor material having a large energy bandwidth instead of silicon. Actually, an attempt was made to produce a field effect transistor using ZnO, which is a transparent oxide semiconductor, and a homologous compound single crystal thin film containing ZnO as a main component or ZnO produced by a reactive solid phase epitaxial method. There has been disclosed a field effect transistor using a homologous amorphous thin film containing as a main component as an active layer (see, for example, Patent Document 5).

However, a simple combination of a conventional transparent transistor and an EC display element has a problem that the TFT is affected by the ionic substance of the electrolyte.
Japanese Patent Laid-Open No. 9-120088 JP 7-152050 A JP-A-6-242474 JP 2003-270671 A JP 2004-198689 A

  The present invention aims to solve the above-described problems and solve the following problems. In other words, the present invention is a multilayer electrochromic display element that is effective for full-color display, which is a problem when using a transistor that is effective for high-definition and high-speed response. It aims at suppressing.

Means for solving the above-mentioned problems are as follows.
<1> On a substrate, an electrochromic layer including at least one electrochromic dye and an electrolyte, at least one transparent thin film transistor, a transparent pixel electrode arranged in a matrix, and a transparent counter electrode and the electrode, Ri name by stacking a plurality of structural units comprising a,
The thin film transistor is homologous compound InMO ₃ (ZnO) _{m (M} is an In, Fe, Ga, or an Al, m represents. An integer of 1 or more and less than 50) the Rukoto to have a thin film A characteristic electrochromic display element.

According to the invention <1>, since the electrode and the thin film transistor (TFT) are transparent, the aperture ratio is increased, and the display performance is improved. In particular, in an EC display element, since the ion migration speed greatly affects the color development / decoloration reaction speed, it is extremely effective to provide a TFT for each constituent unit in the laminated structure. With such a structure, since the number of TFTs to be installed increases, the effect of improving the aperture ratio by making the TFTs transparent is extremely large.
Further, by combining with a transparent TFT, halftone display is easy and high-definition image display is possible. Furthermore, by combining with a transparent TFT, the response speed is improved, and a display element that does not feel uncomfortable when rewritten can be realized.

<2> It is characterized in that at least three structural units are laminated, and the electrochromic layers contained in the three structural units each independently contain yellow, cyan, or magenta electrochromic dyes. The electrochromic display element according to <1>.

  According to the invention <2>, there is a problem in that the aperture ratio is small because the thin film transistor for driving these displays is transparent even in the structure of a multilayer display element effective for full color display. It will be resolved.

<3> The electrochromic display according to <2>, wherein electrochromic layers each containing the magenta, yellow, and cyan electrochromic dyes are laminated in order from the side closer to the viewing side. element.
<4> The electro according to any one of <1> to <3> , wherein a surface of the counter electrode includes a semiconductor nanoporous layer as one of the electrochromic layers. Chromic display element.

< 5 > The electrochromic dye is reversibly developed or decolored by at least one of an electrochemical oxidation reaction and a reduction reaction, and the electrochromic dye is supported on the semiconductor nanoporous layer. ,
The electrochromic display element according to < 4 >, wherein an electrolyte layer is provided between the semiconductor nanoporous layer and the pixel electrode.

According to the inventions < 4 > and < 5 >, since the EC dye is supported on the semiconductor nanoporous layer, the EC dye can be efficiently penetrated to every corner of the display layer, and color development / decoloration reaction can be achieved. The movement speed of ions involved in the reaction can be increased, and the reaction speed is greatly improved. In addition, since the electrode area can be increased, the coloring efficiency is improved by increasing the amount of the dye on the electrode.

< 6 > The electrochromic display element according to < 5 >, wherein the electrolyte layer contains a charge transfer agent.

According to the invention < 6 >, by using the charge transfer agent and the EC dye together, a color-adding effect due to the simultaneous color development of both, and the interaction between the two, the oxidation-reduction reaction proceeds smoothly, and the color development efficiency is further improved. Can be improved.

< 7 > The semiconductor nanoporous layer includes semiconductor fine particles, and the semiconductor fine particles are at least one selected from the group consisting of a single semiconductor, an oxide semiconductor, a compound semiconductor, an organic semiconductor, a composite oxide semiconductor, and a mixture thereof. The electrochromic display element according to any one of the above < 4 > to < 6 >, wherein the electrochromic display element is a seed.

< 8 > The semiconductor fine particles are SnO ₂ —ZnO, Nb ₂ O ₅ —SrTiO ₃ , Nb ₂ O ₅ —Ta ₂ O ₅ , Nb ₂ O ₅ —ZrO ₂ , Nb ₂ O ₅ —TiO ₂ , Ti—SnO. _{2. The} electrochromic display element according to < 7 >, which is at least one complex oxide semiconductor selected from the group consisting of Zr—SnO ₂ , In—SnO ₂ and Bi—SnO ₂ .

< 9 > The electrochromic display according to any one of <1> to < 8 >, wherein the electrochromic dye is at least one selected from the group consisting of an organic compound and a metal complex. element.

  According to the present invention, in a multi-layer electrochromic display element that is effective for full-color display, degradation of display performance due to a decrease in aperture ratio, which is a problem when using a transistor that is effective for high-definition and high-speed response. It is possible to provide an electrochromic display element that suppresses the above.

The electrochromic display element (hereinafter sometimes referred to as EC display element) of the present invention comprises at least one electrochromic dye (hereinafter sometimes referred to as EC dye) and an electrolyte on a substrate. An electrochromic layer (hereinafter sometimes referred to as EC layer), at least one transparent thin film transistor, a transparent pixel electrode arranged in a matrix, and a transparent counter electrode. structural unit comprising Ri Na by stacking a plurality of said thin film transistor, homologous compound InMO ₃ (ZnO) _{m (M} is an in, Fe, Ga, or an Al, m is either less than one or more 50 represents an integer.), characterized in Rukoto to have a thin film.
Hereinafter, after describing each composition, the structure of an electrochromic display element is demonstrated.

<Transparent thin film transistor>
The transparent thin film transistor used in the present invention is not particularly limited as long as it is transparent. A transparent thin film transistor typically has a semiconductor active layer, a gate electrode, a source electrode, a drain electrode, and a gate insulating film, and by making all these transparent, the entire thin film transistor can be made transparent.
As the material of the transparent constituent element of the thin film transistor, a conventionally known transparent material can be employed. For example, a gate electrode, a source electrode, a drain electrode, a gate insulating film, and a semiconductor active layer may be formed using a material containing zinc oxide (ZnO) as a base material. ZnO has a large energy band gap of 3 eV or more, and the conductivity can be controlled by doping impurities therein.
Particularly in transparent thin film transistor used in the present invention, Ru using homologous compound InMO ₃ a (ZnO) _m thin film as a semiconductor active layer. Here, in InMO ₃ (ZnO) _m , M represents In, Fe, Ga, or Al, preferably Ga or Fe, and m represents any integer of 1 to less than 50, preferably Represents an integer of 1 to 10. Hereinafter, it is synonymous in the chemical formula InMO ₃ (ZnO) _m .
Hereinafter, the gate electrode, the source electrode, the drain electrode, the gate insulating film, and the semiconductor active layer will be described in detail.

(Gate electrode, source electrode, drain electrode)
As a material of the gate electrode, the source electrode, and the drain electrode, any material may be used as long as it is transparent to visible light and can provide a low resistivity. For example, an oxide material such as indium oxide (In ₂ O ₃ ), tin oxide (SnO ₂ ), or ZnO, or a material obtained by doping impurities into this oxide material can be used as the transparent conductive film material.

Specifically, as the transparent conductive film material, for example, In ₂ O ₃ doped with tin (Sn) (generally called ITO (Indium Tin Oxide)), SnO ₂ with antimony (Sb) or fluorine (F) doped, ZnO doped with In, ZnO doped with gallium (Ga) (generally called GZO), ZnO doped with Al (commonly called AZO) Etc. can be adopted.

(Gate insulation film)
The gate insulating film disposed between the gate electrode and the semiconductor active layer is mainly composed of, for example, silicon oxide (SiO ₂ ), alumina (Al ₂ O ₃ ), silicon nitride (SiN), or silicon oxynitride. Can be formed. The gate insulating film may contain impurities as long as the object can be achieved.
The gate insulating film may have a two-layer structure by combining the above compositions.

(Semiconductor active layer)
The semiconductor active layer may be formed of a material that is transparent to visible light and has, for example, an energy band gap between the conduction band and the valence band of 3 eV or more and a carrier concentration of 10 ¹⁸ cm ⁻³ or less. .
As such a material, for example, such as those based on zinc oxide (ZnO) and the like, in the present invention, Ru is used as particularly homologous compound InMO ₃ (ZnO) _m thin film semiconductor active layer. The following (1) to (4) can be mentioned as advantages when using the homologous compound InMO ₃ (ZnO) _m thin film.

(1) The homologous compound single crystal InMO ₃ (ZnO) _m thin film manufactured by the reactive solid phase epitaxial method has a defect at the interface between the gate and the active layer because the InO _1.5 layer forms a flat thin film surface at the atomic level. Thus, a thin film field effect transistor with little gate leakage current can be manufactured.
In InMO ₃ (ZnO) _m , the value of m is preferably an integer of 1 or more and less than 50. In principle, the value of m can be up to infinity, but in practice, if the value of m becomes too large, the variation of m in the film increases and oxygen defects are likely to occur. As a result, the electrical conductivity of the film increases, making it difficult to make a normally-off type FET.

(2) Since the band gap energy of the homologous compound InMO ₃ (ZnO) _m containing ZnO as a main constituent is larger than 3.3 eV, it is transparent to visible light having a wavelength of 400 nm or more. Therefore, by using a homologous compound single crystal InMO ₃ (ZnO) _m thin film as an active layer, a thin film field effect transistor with high visible light transmittance and no generation of photoinduced current due to visible light can be produced.

(3) The homologous compound InMO ₃ (ZnO) _m single crystal thin film produced by the reactive solid phase epitaxial method has a very small deviation from the stoichiometric composition and is a good insulator near room temperature. By using a crystalline InMO ₃ (ZnO) _m thin film as an active layer, a transparent thin film field effect transistor with good switching characteristics can be manufactured with a normally-off operation.

(4) The amorphous state in which a homologous compound containing ZnO is formed at room temperature by the reactive solid phase epitaxial method is stable up to a high temperature of about 1000 ° C., and the electron carrier mobility in that state is higher than that of amorphous silicon. 10 times larger. Therefore, a field effect transistor using a homologous amorphous thin film as an active layer has a higher visible light transmittance than a silicon amorphous field effect transistor, operates stably against light irradiation, and operates at a higher speed. I can expect that.

When using a homologous compound InMO ₃ (ZnO) _m thin film as the semiconductor active layer, the gate insulating film is preferably Al ₂ O ₃ . Further, the thickness of the homologous compound InMO ₃ (ZnO) _m thin film is preferably 50 nm to 1000 nm, and more preferably 100 nm to 500 nm.
Hereinafter, a method for producing a homologous compound InMO ₃ (ZnO) _m thin film will be described in detail.

As a method for forming a homologous compound InMO ₃ (ZnO) _m thin film, a ZnO single crystal thin film is epitaxially grown on the substrate by MBE method, pulse laser deposition method (PLD method) or the like, and then, on the ZnO thin film, Examples include a method of growing a homologous compound thin film described as InMO ₃ (ZnO) _m by a MBE method, a pulsed laser deposition method (PLD method) or the like using a polycrystalline sintered body of the oxide as a target. It is done.
The obtained homologous compound InMO ₃ (ZnO) _m thin film does not need to be a single crystal film, and may be a polycrystalline film or an amorphous film. Finally, it is preferable to cover the whole thin film with a high melting point compound such as Al ₂ O ₃ and to carry out a heat diffusion treatment at high temperature and atmospheric pressure containing ZnO vapor.

If InMO ₃ (ZnO) _m and the ZnO film diffuse and react with each other and the temperature is set appropriately, a uniform composition InMO ₃ (ZnO) _{m ′} is obtained. m ′ is determined from the ratio of InMO ₃ (ZnO) _m and ZnO film thickness. When the ZnO film thickness is less than 5 nm and the InMO ₃ (ZnO) _m film thickness exceeds 100 nm, m ′ is substantially the same as m. become.

A suitable temperature is 800 degrees or more and 1600 degrees or less, more preferably 1200 degrees or more and 1500 degrees or less. If it is less than 800 degrees, diffusion is slow and InMO ₃ (ZnO) _m having a uniform composition cannot be obtained. On the other hand, if it exceeds 1600 degrees, evaporation of ZnO cannot be suppressed and InMO ₃ (ZnO) _m having a uniform composition cannot be obtained.

Moreover, the homologous single crystal film containing ZnO obtained by the reactive solid phase epitaxial growth method is close to the stoichiometric composition, exhibits a high insulating property of 10 ⁸ W · cm or more at room temperature, and is a normally-off field effect type. Suitable for transistors.

  Next, a method for manufacturing a top gate type MIS field effect transistor using the obtained homologous single crystal thin film containing ZnO as a main component as an active layer will be described.

  First, a gate insulating film and a metal film for a gate electrode are formed on a homologous single crystal thin film containing ZnO epitaxially grown on a substrate as a main component.

Al ₂ O ₃ is most suitable for the gate insulating film. Au, Ag, Al, Cu, or the like can be used for the metal film for the gate electrode. A gate electrode is manufactured by optical lithography and dry etching or a lift-off method, and finally a source electrode and a drain electrode are manufactured.

(Insulating film)
In the electrochromic display element of the present invention, it is preferable to provide an insulating film so that the thin film transistor is not deteriorated by the influence of an ionic substance contained in the electrolyte layer described below. The composition of the insulating film is not particularly limited as long as it has insulating properties, but it is preferable to use polyimide.

FIG. 1 shows a schematic diagram of the configuration as an example of the transparent thin film transistor according to the present invention.
In FIG. 1, a top gate type MIS field effect transistor (MIS-FET) 10 is shown. In the transparent thin film transistor of FIG. 1, a homologous compound single crystal thin film (InMO ₃ (ZnO) _m ) containing ZnO as a main component used in the present invention is provided as a semiconductor active layer 12, and a drain electrode 14 and a source electrode 16 are formed thereon. Then, the insulating film 18 and the gate electrode 20 are formed.
The drain electrode 14, the source electrode 16, and the gate electrode 20 may be made of any material as long as it is transparent to visible light and can have a low resistivity. For example, an oxide material such as indium oxide (In ₂ O ₃ ), tin oxide (SnO ₂ ), or ZnO, or a material obtained by doping impurities into this oxide material can be used as the transparent conductive film material.

Specifically, as the transparent conductive film material, for example, In ₂ O ₃ doped with tin (Sn) (generally called ITO (Indium Tin Oxide)), SnO ₂ with antimony (Sb) or fluorine (F) doped, ZnO doped with In, ZnO doped with gallium (Ga) (generally called GZO), ZnO doped with Al (commonly called AZO) Etc. can be adopted.
As described above, Al ₂ O ₃ is most suitable for the gate insulating film 18.

  The shape of the field effect transistor according to the present invention includes a top gate type MIS field effect transistor (MIS-FET), J-FET, and the like.

  Even when a homologous amorphous thin film containing ZnO as a main constituent is used, a top-gate MIS field effect transistor can be similarly produced. In the case of an amorphous thin film, it is not necessary to perform epitaxial growth, so that ZnO epitaxial growth and a high temperature annealing process can be eliminated. Therefore, the gate electrode can be formed between the substrate and the film, and a bottom gate MIS field effect transistor can also be manufactured.

  In the electrochromic display element of the present invention, the height from the lower surface of the semiconductor active layer of the transparent transistor to the gate electrode is preferably 50 nm to 500 nm, and more preferably 100 nm to 200 nm. If it is thinner than 50 nm, it becomes difficult to produce stably, and if it is thicker than 500 nm, the driving voltage increases and power consumption increases, which is not preferable.

  The channel length is preferably 0.01 mm to 0.1 mm, and more preferably 0.02 mm to 0.08 mm. The channel width is preferably 0.1 mm to 0.5 mm, and more preferably 0.1 mm to 0.3 mm.

<Pixel electrode and counter electrode (transparent electrode)>
The pixel electrode and the counter electrode used in the present invention are transparent electrodes and are arranged so as to face each other. The pixel electrode and the counter electrode may have the same composition or different ones. The transparent electrode refers to an electrode having a light transmittance of at least 50%.
The transparent electrode is not particularly limited as long as it is transparent and can conduct electricity, and can be appropriately selected according to the purpose. For example, indium tin oxide (ITO), tin oxide (NESA), fluorine-doped oxide Examples include tin (FTO), indium oxide, zinc oxide, platinum, gold, silver, rhodium, copper, chromium, and carbon. Among these, metal oxides represented by tin oxide-indium oxide (ITO), tin oxide, zinc oxide and the like are preferably used, and furthermore, the surface resistance value is low, the heat resistance is good, and the chemical stability is high. In view of high light transmittance, tin oxide (FTO) doped with fluorine and indium tin oxide (ITO) are preferable.
In particular, the electrochromic display element of the present invention may be provided with an electrolyte layer or a semiconductor nanoporous layer described below adjacent to the transparent electrode, and it must be chemically stable even when in contact therewith. Therefore, tin oxide (FTO) and indium tin oxide (ITO), which are oxides, are suitable.

  The thickness of the pixel electrode and the counter electrode is not particularly limited and can be appropriately selected according to the purpose. For example, it is generally 0.1 μm or more, more specifically 0.1 μm to 20 μm. is there.

  As for the transparent electrode, for example, those described in pages 232 to 239 of “Liquid Crystal Device Handbook” (edited by the Japan Society for the Promotion of Science 142nd Committee, Nikkan Kogyo Shimbun, 1989) are used. The transparent electrode can be formed by a sputtering method, a sol-gel method, or a printing method.

  In the case of a reflective optical element, the electrode farthest from the viewing direction is a metal oxide layer represented by tin oxide-indium oxide (ITO), tin oxide, zinc oxide, or the like. In addition, a conductive polymer or a metal layer represented by carbon, copper, aluminum, gold, silver, nickel, platinum, or the like can be used.

<Electrochromic layer>
The electrochromic layer in the present invention is a layer containing an electrochromic dye and an electrolyte. There is no restriction | limiting in particular except this, For example, what contained EC dye in the electrolyte layer containing electrolyte (electrolyte EC layer), what added EC dye to the semiconductor nanoporous layer mentioned later, etc. are mentioned. Of course, a layer containing an electrochromic dye may be formed separately from the electrolyte layer and the semiconductor nanoporous layer. That is, the electrochromic layer refers to a layer that can contain an EC dye, including an electrolyte layer, a semiconductor nanoporous layer, a layer containing an EC dye (including a layer having these functions), and the like.

  The EC dye is reversibly blackened or decolored by an oxidation-reduction reaction. Specifically, the light transmittance at a wavelength of 300 to 750 nm is preferably 10% or less, and a wavelength of 350 to 700 nm. The light transmittance is more preferably 10% or less, and the light transmittance at a wavelength of 400 to 600 nm is further preferably 10% or less. The EC dye exhibiting such color development and decoloring behavior is not particularly limited, but two or more EC dyes are preferably used in combination, and specific combinations will be described later.

(Semiconductor nanoporous layer)
The semiconductor nanoporous layer is formed between at least one or both of the inner surfaces of the transparent electrode, preferably on the counter electrode side, between the transparent electrodes.
The semiconductor nanoporous layer has a porous structure so that the surface and the inside thereof have many micropores capable of supporting an EC dye and, if necessary, a charge transfer agent.

  The semiconductor nanoporous layer may have a single layer structure, but is formed in a multilayer structure, for example, a 2-4 layer structure, and carries the same type of EC dye for each semiconductor nanoporous layer of the multilayer structure. Thus, the color intensity can be adjusted and the color intensity can be enhanced. Moreover, blackening can be easily achieved by carrying EC dye of a different color for each layer of the semiconductor nanoporous layer having a multilayer structure.

1-5000 m < ² > / g is preferable and, as for the specific surface area of a semiconductor nanoporous layer, 10-2500 m < ² > / g is more preferable. Here, the specific surface area means the BET specific surface area obtained from the adsorption amount of nitrogen gas. If the specific surface area is too small, the adsorption amount of the EC dye cannot be increased, and the object of the present invention may not be achieved.
The thickness of the semiconductor nanoporous layer (total thickness in the case of a multilayer structure) is preferably 5 μm to 200 μm, and more preferably 10 μm to 50 μm. If the thickness is less than 5 μm, the amount of dye adsorbed decreases, so that the display performance deteriorates. If the thickness is more than 200 μm, the driving voltage increases, which is not preferable.

  The semiconductor nanoporous layer may have any configuration, but it is preferable from the viewpoint of ease of production to form a porous state by filling fine particles. The semiconductor fine particles contained in the semiconductor nanoporous layer are not particularly limited and can be appropriately selected according to the purpose. For example, a single semiconductor, an oxide semiconductor, a compound semiconductor, an organic semiconductor, a composite oxide semiconductor, Or a mixture thereof may be mentioned, and these may contain impurities as a dopant. There is no particular limitation on the form of the semiconductor, and it may be single crystal, polycrystal, amorphous, or a mixed form thereof.

  Examples of the single semiconductor include silicon (Si), germanium (Ge), and tellurium (Te).

The oxide semiconductor is a metal oxide and has semiconductor properties. For example, TiO ₂ , SnO ₂ , Fe ₂ O ₃ , SrTiO ₃ , WO ₃ , ZnO, ZrO ₂ , Ta ₂ O ₅ , Nb ₂ Examples thereof include O ₅ , V ₂ O ₅ , In ₂ O ₃ , CdO, MnO, CoO, TiSrO ₃ , KTiO ₃ , Cu ₂ O, sodium titanate, barium titanate, and potassium niobate.

  Examples of the compound semiconductor include cadmium sulfide, zinc sulfide, lead sulfide, silver sulfide, antimony sulfide, bismuth sulfide, cadmium selenide, lead selenide, cadmium Examples include telluride, zinc phosphide, gallium phosphide, indium phosphide, cadmium phosphide, gallium-arsenic selenide, copper-indium selenide, copper-indium sulfide, and the like.

  Examples of the organic semiconductor include polythiophene, polypyrrole, polyacetylene, polyphenylene vinylene, polyphenylene sulfide, and the like.

Examples of the complex oxide semiconductor include SnO ₂ —ZnO, Nb ₂ O ₅ —SrTiO ₃ , Nb ₂ O ₅ —Ta ₂ O ₅ , Nb ₂ O ₅ —ZrO ₂ , Nb ₂ O ₅ —TiO ₂ , _{Ti-SnO 2, Zr-SnO} 2, Bi-SnO 2, In-SnO 2, and the like. The SnO ₂ —ZnO is obtained by coating relatively large ZnO particles (particle size: about 0.2 μm) around the center with SnO ₂ ultrafine particles (particle size: about 15 nm). _{SnO 2: ZnO = 70: 30~30} : is preferably in the range of 70. The _{Nb 2 O 5 -SrTiO 3, Nb} 2 O 5 -Ta 2 O 5, Nb 2 O 5 -ZrO 2, and Nb ₂ O ₅ complex, such as Nb ₂ O ₅ -TiO ₂ includes a Nb ₂ O ₅ The mass ratio is 8: 2 to 2: 8.

  The shape of the semiconductor fine particles is not particularly limited and can be appropriately selected according to the purpose. The shape may be any of a spherical shape, a nanotube shape, a rod shape, and a whisker shape, and two or more types having different shapes may be used. Fine particles can also be mixed. In the case of the spherical particles, the number average particle size is preferably 0.1 to 1000 nm, more preferably 1 to 100 nm. Two or more kinds of fine particles having different particle size distributions may be mixed. In the case of the rod-like particles, the aspect ratio is preferably 2 to 50000, and more preferably 5 to 25000.

  The method for forming the semiconductor nanoporous layer is not particularly limited and may be appropriately selected depending on the type of semiconductor. For example, metal anodization, cathode deposition, screen printing, sol-gel method, heat Examples include oxidation, vacuum deposition, DC and DF sputtering, chemical vapor deposition, metalorganic chemical vapor deposition, molecular beam deposition, laser ablation, and the like. A porous layer can also be produced.

(Method for forming oxide semiconductor nanoporous layer)
As one method for forming an oxide semiconductor (metal oxide) nanoporous layer, in a solution containing a metal oxide precursor and a compound having one or more functional groups that interact with the metal oxide precursor A first step of producing a composite gel by reacting the metal oxide precursor to obtain a colloidal dispersion sol composed of metal oxide fine particles, and applying the sol to a support and drying or baking the sol And a second step of forming a semiconductor nanoporous layer having micropores on the transparent conductive film on the transparent insulating substrate (hereinafter also referred to as “composite gelation method”). ).

  In the first step, since the formation reaction of metal oxide fine particles proceeds in a gel whose diffusion is restricted, colloid in which fine particles having a small particle diameter are uniformly dispersed without formation of coarse particles or sedimentation of particles. A dispersed sol solution can be obtained. In the so-called sol-gel method, when metal oxide precursors are, for example, metal alkoxides, they are gelled by hydrolysis and dehydration condensation reaction. In this case, -M-OM- (here , M is a metal element, and O is an oxygen element), a chemically strong three-dimensional bond network is formed and cannot be solated again. Once gelled, it can be processed by means such as coating. Can not. On the other hand, in a method of obtaining a composite gel by reacting a metal oxide precursor in a solution containing the metal oxide precursor and a compound that interacts with the metal oxide precursor, By utilizing the interaction property of the compound that interacts with the body, it can be made into a sol again and can have excellent processability.

Here, examples of the metal oxide precursor include metal compounds such as metal halides, metal complex compounds, metal alkoxides, metal carboxylates, and chelate compounds that are soluble in the solvent used. Specific examples of the compound include metals such as TiCl ₄ (titanium tetrachloride), ZnCl ₂ (zinc chloride), WCl ₆ (tungsten hexachloride), SnCl ₂ (stannous chloride), and SrCl ₆ (strontium chloride). Halides, nitrates such as Ti (NO ₃ ) ₄ (titanium nitrate), Zn (NO ₃ ) ₂ (zinc nitrate), Sr (NO ₃ ) ₂ (strontium nitrate), and general formula: M (OR) n (however, , M is a metal element, R is an alkyl group, and n is an oxidation number of the metal element).

  Examples of the metal alkoxide include zinc diethoxide, tungsten hexaethoxide, vanadyl ethoxide, tin tetraisopropoxide, strontium diisopropoxide, and the like.

  For example, when forming a metal oxide layer of titanium oxide, examples of the metal alkoxide include titanium tetraisopropoxide, titanium tetranormal propoxide, titanium tetraethoxide, titanium tetranormal butoxide, titanium tetraisobutoxide, and titanium tetra. Tertiary butoxide and the like can be preferably used.

  Examples of the functional group that interacts with the metal oxide precursor include a carboxyl group, an amino group, and a hydroxyl group. Moreover, as a functional group which interacts with a metal oxide precursor, you may have 1 or more types of the said functional groups like an amic acid structure. The compound having at least one functional group that interacts with the metal oxide precursor is a compound having at least one functional group selected from a carboxyl group, an amino group, a hydroxyl group, and an amino acid structure. Particularly preferred are polymer compounds. Specific examples of such a low molecular weight compound include dicarboxylic acid, diamine, diol, diamic acid and the like.

  Specific examples of the polymer compound include a polymer compound having at least one functional group selected from a carboxyl group, an amino group, a hydroxyl group, and an amic acid structure in the main chain, side chain, or cross-linked portion. The main chain structure of the polymer compound is not particularly limited, but a polyethylene structure, a polystyrene structure, a polyacrylate structure, a polymethacrylate structure, a polycarbonate structure, a polyester structure, a cellulose structure, Examples thereof include a silicone structure, a vinyl polymer structure, a polyamide structure, a polyamideimide structure, a polyurethane structure, a polyurea structure, etc., or an arbitrary structure such as a copolymer structure.

  Furthermore, as a polymer compound having at least one functional group selected from the carboxyl group, amino group, hydroxyl group, and amic acid structure in the main chain, side chain, or cross-linked portion, the polymer compound interacts with the metal oxide precursor. From the viewpoint of suitable form, the use of polyacrylic acid having a carboxyl group in the side chain is particularly preferred. The polymer compound having at least one functional group that interacts with the metal oxide precursor has a carboxyl group, an amino group, a hydroxyl group, and an amic acid structure with the polymer compound having an interacting functional group. It may be a copolymer with a polymer compound having the same main chain structure as described above. The polymer compound having at least one functional group that interacts with the metal oxide precursor has a mixed system of two or more, or a carboxyl group, an amino group, a hydroxyl group, and an amic acid structure, depending on the purpose. A mixed system with a polymer compound having a main chain structure similar to that described above may be used. The average degree of polymerization of the polymer compound having one or more functional groups that interact with the metal oxide precursor is preferably 100 to 10,000,000, and more preferably 5,000 to 250,000.

  As the solvent, alcohols such as methanol, ethanol, isopropanol and butanol, and metal oxide precursors such as formamide, dimethylformamide, dioxane and benzene can be dissolved and do not react with the metal oxide precursor. Can be used.

  Hereinafter, the method for forming a semiconductor nanoporous layer will be described in detail by taking as an example the case of using a metal alkoxide as the metal oxide precursor.

First, the metal alkoxide is added to the solvent (for example, an organic solvent such as alcohol). Further, water necessary for partially hydrolyzing the metal alkoxide and an acid such as hydrochloric acid, nitric acid, sulfuric acid or acetic acid are added as a catalyst. The amount of water and acids added here can be appropriately selected according to the degree of hydrolyzability of the metal alkoxide used.
Next, the resulting mixed solution is heated or refluxed at room temperature (about 25 ° C., the same applies to room temperature) to 150 ° C., preferably room temperature to 100 ° C. under a stream of dry nitrogen while stirring. The reflux temperature and time can also be appropriately selected according to the hydrolyzability of the metal oxide precursor used.
As a result of the reflux, the metal alkoxide is partially hydrolyzed. That is, since the amount of the water contained in the mixed solution is small enough not to sufficiently hydrolyze the alkoxyl group of the metal alkoxide, the metal represented by the general formula: M (OR) _n In alkoxides, all of the —OR groups are not hydrolyzed, resulting in a partially hydrolyzed state. In the partially hydrolyzed metal alkoxide, the polycondensation reaction does not proceed. For this reason, even if the chain | strand of -MOMM is formed between the said metal alkoxides, the said metal alkoxide will be in an oligomer state. The mixed solution after reflux containing the metal alkoxide in the oligomer state is colorless and transparent and hardly increases in viscosity.

  Next, the temperature of the mixed solution after reflux is lowered to room temperature, and the mixed solution is a polymer compound (preferably polyacrylic acid) having at least one functional group selected from a carboxyl group, an amino group, a hydroxy group, and an amino acid structure. Acid). In this case, the polymer compound that is originally difficult to dissolve in an organic solvent such as alcohols is easily dissolved in the mixed solution to obtain a transparent sol. This is considered to be because the carboxyl group of the polymer compound and the metal alkoxide are bonded by a salt formation reaction to form a polymer complex compound. This transparent sol is usually a colorless and transparent uniform solution.

  By adding an excessive amount of water to the transparent sol and maintaining the reaction at room temperature to 150 ° C., preferably about room temperature to 100 ° C., the reaction is continued for several minutes (for example, 5 minutes) to about 1 hour. The transparent sol is gelled to form a composite gel having a crosslinked structure of the polymer compound and the metal alkoxide.

  When the resulting composite gel is further maintained at room temperature to 90 ° C. (usually about 80 ° C.) for 5 to 50 hours and the reaction is continued, the composite gel is dissolved again to obtain a translucent metal oxide fine particle colloidal dispersion sol. . This is because the polycondensation reaction proceeds by the hydrolysis reaction of the metal alkoxide, and the salt structure of the polymer compound and the metal alkoxide is decomposed to change into metal oxide fine particles, carboxylic acid ester, and the like. Is due to.

  The semitransparent metal oxide fine particle colloidal dispersion sol obtained as described above is applied to an electrode layer provided on a substrate, and then dried or baked to form a metal oxide film having fine pores.

  The coating method can be performed by a known method without any particular limitation. Specific examples include a dip coating method, a spin coating method, a wire bar method, and a spray coating method. In addition, for example, air drying, drying using an oven or the like, and vacuum freeze drying are possible for drying. Moreover, the method of evaporating a solvent using apparatuses, such as a rotary evaporator, may be used. In this case, the drying temperature, time, etc. can be appropriately selected according to the purpose.

  Further, the polymer compound or its reaction product may not be removed only by drying the metal oxide fine particle colloidal dispersion sol (removal of the liquid component containing the solvent) at a drying temperature. In such a case, it is preferable to perform firing in order to remove these further to obtain a pure metal oxide. The firing can be performed using, for example, a furnace, and the firing temperature varies depending on the type of the polymer compound having the functional group used, but a low temperature is suitable for multi-layering. About 100 ° C to 700 ° C is preferable, and 100 ° C to 400 ° C is more preferable.

  The firing causes crystallization of the metal oxide fine particles and sintering of the metal oxide fine particles, and at the same time, the organic polymer component is thermally decomposed and disappears.

  In the formation of the semiconductor nanoporous layer, the formation reaction of metal oxide fine particles proceeds in a composite gel in which diffusion is regulated, so that formation of coarse particles, aggregation due to sedimentation of particles does not occur, and the like. A metal oxide fine particle colloidal dispersion sol in which small ultrafine particles are uniformly dispersed can be obtained.

  Regarding the size of the metal oxide fine particles of the semiconductor nanoporous layer, the period of the metal oxide fine particle aggregated structure, the volume ratio of the metal oxide fine particle aggregated phase and the void phase, etc., for example, relative to the metal oxide precursor The addition amount of the compound having one or more functional groups that interact with the metal oxide precursor is combined with the compound having one or more functional groups that interact with the metal oxide precursor and the metal oxide precursor. The ratio of the solid component to the whole mixed solution can be controlled to a desired level.

  That is, when the addition amount of the compound having one or more functional groups to be fired with the metal oxide precursor is increased, the volume ratio of the void phase in the obtained semiconductor nanoporous layer is increased, and the metal oxide precursor and the metal oxide are oxidized. If the ratio of the solid component combined with the compound having at least one functional group that interacts with the precursor of the compound to the whole mixed solution is reduced, the cycle of the resulting metal oxide fine particle aggregated structure becomes smaller, and the density of the void phase However, the size of the metal oxide fine particles themselves increases.

  The addition amount of the compound having one or more functional groups that interact with the metal oxide precursor with respect to the metal oxide precursor can be appropriately selected depending on the ratio of the solid component to the whole mixed solution, In general, the mass ratio is preferably 0.1 to 1, and more preferably 0.2 to 0.8. By setting it as such a range, it is possible to more effectively prevent the formation of a large three-dimensional network of -M-OM- and hinder the re-dissolution of the composite gel, and the dense semiconductor nanometer with few macropores. Make the porous layer easier. On the other hand, if the addition amount is increased to exceed 1, relatively large voids are generated, and a transparent semiconductor nanoporous layer tends to be formed.

  The ratio of the solid component to the entire mixed solution can be appropriately selected because it varies depending on the amount of the metal oxide precursor and the compound having one or more functional groups that interact with the metal oxide precursor. However, generally 1-10 mass% is preferable and 2-5 mass% is more preferable. When the proportion is less than 1% by mass, the progress of the complex gelation reaction is slow, and metal oxide fine particles are formed in a transparent sol state with high fluidity, and coarse particles are formed, whereas 10% by mass. If it exceeds 50%, the progress from the transparent sol to the composite gel is fast, and a uniform composite gel may not be obtained.

  Below, the case where tungsten hexaethoxide is used as the metal alkoxide is taken as an example, and the method for forming the tungsten oxide porous layer will be described in more detail.

  First, tungsten hexaethoxide is added to alcohol to prepare a mixed solution. In this case, water and an acid as a catalyst are added to the alcohol, and the water is preferably 0.1 mole to equimolar to tungsten hexaethoxide, and the acid is tungsten hexaethoxide. The molar amount is preferably 0.05 times to 0.5 times mol. The resulting mixed solution is refluxed under a stream of dry nitrogen with stirring, for example, at room temperature to 80 ° C. The reflux temperature and time here are preferably about 30 minutes to 3 hours at 80 ° C. As a result of this reflux, a transparent mixed solution is obtained.

  In this mixed solution, tungsten hexaethoxide is partially hydrolyzed and is in an oligomer state. The temperature of the mixed solution is lowered to room temperature and polyacrylic acid is added. Polyacrylic acid, which is essentially insoluble in alcohol, dissolves easily in this mixed solution, and a colorless transparent sol is obtained. This is because the carboxylic acid of polyacrylic acid and tungsten hexaethoxide are bonded by a salt formation reaction to form a polymer complex compound. When an excessive amount of water is further added to this transparent sol and kept at room temperature to 80 ° C., the transparent sol gels in about several minutes to 1 hour, and a composite of a crosslinked structure containing at least polyacrylic acid and tungsten hexaethoxide Gelation is formed.

  When this composite gel is held at about 80 ° C. for 5 to 50 hours, the composite gel is dissolved again to obtain a translucent sol. This is because the hydrolysis and polycondensation reaction of tungsten hexaethoxide proceeds, and the salt structure of polyacrylic acid and tungsten hexaethoxide decomposes to change into titanium oxide and carboxylic acid ester. .

  The obtained sol solution is applied to a suitable substrate by a dip coating method or the like and heated to a high temperature of about 100 ° C. to 600 ° C. With this heating, crystallization of tungsten oxide fine particles and sintering between the tungsten oxide fine particles proceed, and at the same time, the polymer phase is thermally decomposed to form film-like tungsten oxide fine particles in which tungsten oxide is aggregated in a phase separated state. It becomes.

  The amount of polyacrylic acid relative to tungsten hexaethoxide is preferably 0.3 to 0.7 by weight. By setting the mass ratio to 0.3 or more, it is possible to prevent the case where the gel does not dissolve due to the formation of a large three-dimensional network of -MOMM, and to 0.7 or less. It is possible to more effectively prevent a relatively large void from being formed and forming a transparent layer.

  Moreover, as a ratio with respect to the said whole mixed solution of the solid component of tungsten hexaethoxide and polyacrylic acid, 1-10 mass% is preferable. By making the ratio 1% by mass or more, the progress of the composite gelation reaction is slow, and tungsten oxide fine particles can be formed in a highly fluid sol state, so that coarse tungsten oxide fine particles can be formed more effectively. Can be prevented. On the other hand, when the content is 10% by mass or less, the case where a uniform composite gel cannot be obtained with a rapid progress from the transparent sol to the composite gel can be more unlikely to occur.

(Method for forming compound semiconductor nanoporous layer)
Examples of the method for forming the compound semiconductor nanoporous layer include (1) electrolytic deposition, (2) chemical bath deposition, and (3) photochemical deposition, and are specifically described below.

(1) Electrolytic Deposition Method The electrolytic deposition method includes an electrode in which a transparent conductive film on a transparent insulating substrate is formed in an electrolyte containing at least ions of elements to be deposited, and an electrode facing the electrode. It arrange | positions and raise | generates an oxidation-reduction reaction electrochemically between these electrodes, The said compound semiconductor layer is formed on the electrode in which the transparent conductive film was formed. “Surface Technology” Vol. 49, no. See pages 1, 3 and 1998.

(2) Chemical bath deposition method In the chemical bath deposition method, an electrode on which a transparent conductive film is formed on a transparent insulating substrate is placed in a solution containing at least one kind of deposited ions, and the temperature of the solution is adjusted. And the ion concentration adjustment causes a reduction reaction to form the compound semiconductor layer on the electrode. “Journal of Applied Physics” vol. 82, 2, 655, 1997 can be referred to.

(3) Photochemical deposition method In the photochemical deposition method, an electrode in which a transparent conductive film is formed on a transparent insulating substrate is placed in a solution containing at least one kind of sodium thiosulfate and metal ions, and ultraviolet rays are applied to the electrode. Irradiation causes a photoreaction, and the compound semiconductor layer is formed on the electrode. “Japan Journal Applied Physics” vol.36, L1146, 1997 can be referred to.

(Formation method of composite oxide semiconductor nanoporous layer)
The composite oxide semiconductor nanoporous layer is a method in which an oxide semiconductor nanoporous layer is further formed by a sol-gel method on the oxide semiconductor nanoporous layer formed by the above method, or two types of composites are formed. Examples thereof include a method of applying a paste mixed with oxide semiconductor particles on an electrode.

  Specifically, acetic acid is dropped into an aqueous oxide semiconductor colloid solution, and the oxide semiconductor powder and alcohol to be combined are added little by little to the gel solution mixed well in a mortar and mixed well. Further, a surfactant is added and mixed well, and this is spray-coated on a hot plate (100 to 120 ° C.) on a fluorine-doped tin oxide conductive film glass (FTO) electrode and baked, thereby producing semiconductor fine particles. Crystallization and firing of semiconductor fine particles proceed to form a composite oxide semiconductor nanoporous layer having a desired porosity.

(Electrochromic dye)
The electrochromic dye (EC dye) is preferably carried in the surface of the semiconductor nanoporous layer and in the internal micropores and, if necessary, contained in a dissolved or dispersed state in the electrolyte layer. . The EC dye is not particularly limited as long as it exhibits an effect of developing or erasing black by at least one of an electrochemical oxidation reaction and a reduction reaction, and can be appropriately selected according to the purpose. For example, an organic dye And metal complex dyes are preferred, and organic dyes are preferred. These EC dyes may be used alone or in combination of two or more.

  Examples of the metal complex dye include Prussian blue, metal-bipyridyl complex, metal phenanthroline complex, metal-phthalocyanine complex, metaferricyanide, and derivatives thereof.

  Examples of the organic dye include (1) pyridine compounds, (2) conductive polymers, (3) styryl compounds, (4) donor / acceptor type compounds, (5) other organic dyes, Etc.

  Examples of (1) pyridine compounds include viologen, heptyl viologen (such as diheptyl viologen dibromide), methylene bispyridinium, phenanthroline, azobipyridinium, 2,2-bipyridinium complex, and quinoline / isoquinoline.

  Examples of the conductive polymer (2) include polypyrrole, polythiophene, polyaniline, polyphenylenediamine, polyaminophenol, polyvinylcarbazole, polymer viologen polyion complex, TTF, and derivatives thereof.

  Examples of the (3) styryl compounds include 2- [2- [4- (dimethylamino) phenyl] ethenyl] -3,3-dimethylindolino [2,1-b] oxazolidine, 2- [4- [4- (Dimethylamino) phenyl] -1,3-butadienyl] -3,3-dimethylindolino [2,1-b] oxazolidine, 2- [2- [4- (dimethylamino) phenyl] ethenyl]- 3,3-dimethyl-5-methylsulfonylindolino [2,1-b] oxazolidine, 2- [4- [4- (dimethylamino) phenyl] -1,3-butadienyl] -3,3-dimethyl-5 -Sulfonylindolino [2,1-b] oxazolidine, 3,3-dimethyl-2- [2- (9-ethyl-3-carbazolyl) ethenyl] indolino [2,1-b] oxazolidine 2- [2- [4- (acetylamino) phenyl] ethenyl] -3,3-dimethyl-indolino [2,1-b] oxazolidine, and the like.

  Examples of the (4) donor / acceptor type compounds include tetracyanoquinodimethane and tetrathiafulvalene.

  Examples of (5) other organic dyes include carbazole, methoxybiphenyl, anthraquinone, quinone, diphenylamine, aminophenol, Tris-aminophenylamine, phenylacetylene, cyclopentyl compound, benzodithiolium compound, squalium salt, cyanine, rare earth Examples include phthalocyanine complexes, ruthenium diphthalocyanines, merocyanines, phenanthroline complexes, pyrazolines, redox indicators, pH indicators, and derivatives thereof.

  Further, as the EC dye, a reduction coloring type that shows colorless or ultra-light color in the oxidation state and develops color in the reduction state, an oxidation coloring type that shows colorless or ultra-light color in the reduction state and develops color in the oxidation state, It may be any of the multicolor coloring types that exhibit color development in the reduced state or the oxidized state, and develop several kinds of colors depending on the degree of reduction or oxidation, and can be appropriately selected according to the purpose.

  In the EC dye, a combination of coloring and decoloring black by oxidation-reduction reaction is 2- {2- [4- (dimethylamino) phenyl] ethenyl} -3, 3-dimethyl-5-phosphonoindolino [2,1-b] oxazoline and 2- {2- [4- (dimethylamino) phenyl] -1,3-butadienyl} -3,3-dimethyl-5 Carboxyindolino [2,1-b] oxazoline and 2- {2- [4- (methoxy) phenyl] ethenyl} -3,3-dimethyl-5-phosphonoindolino [2,1-b] oxazoline Combination, etc. are mentioned. Examples of the combination of reducing coloring dyes include a combination of bis- (2-phosphonoethyl) -4,4'-bipyridinium dibromide and [β- (10-phenothiazyl) propoxy] phosphonic acid.

  As the EC dye used in the present invention, any absorption maximum and absorption band may be used, but a dye having an absorption maximum in the yellow region (Y), magenta region (M), or cyan region (C). Is preferably used. A method for performing full color display by mixing a yellow dye, a magenta dye and a cyan dye is detailed in “Color Chemistry” (written by Sumio Tokita, Maruzen, 1982). Here, the yellow region is a range of 430 to 490 nm, the magenta region is a range of 500 to 580 nm, and the cyan region is a range of 600 to 700 nm.

  There is no restriction | limiting in particular as a method to carry | support EC pigment | dye on the surface and the inside of the said semiconductor nanoporous layer, A well-known technique can be used. For example, a dry process such as a vacuum deposition method, a coating method such as spin coating, an electric field deposition method, an electric field polymerization method, or a natural adsorption method in which a solution of a compound to be supported is immersed can be appropriately selected. Above all, the natural adsorption method does not require special equipment that can support functional molecules evenly throughout the fine pores of the metal oxide layer and does not require special equipment. It has many advantages such as no extra amount and is a preferred method.

  Specifically, a method of immersing a transparent substrate having a well-dried semiconductor nanoporous layer in an EC dye solution or applying a dye solution to the semiconductor nanoporous layer can be used. In the former case, an immersion method, a dip method, a roller method, an air knife method or the like can be used. In the case of the dipping method, the dye may be adsorbed at room temperature, or may be carried out by heating and refluxing as described in JP-A-7-249790. Examples of the latter application method include a wire bar method, a slide hopper method, an extrusion method, a curtain method, a spin method, and a spray method.

  Examples of the solvent for dissolving the EC dye include water, alcohols (methanol, ethanol, t-butanol, benzyl alcohol, etc.), nitriles (acetonitrile, propionitrile, 3-methoxypropionitrile, etc.), nitromethane, Halogenated hydrocarbons (dichloromethane, dichloroethane, chloroform, chlorobenzene, etc.), ethers (diethyl ether, tetrahydrofuran, etc.), dimethyl sulfoxide, amides (N, N-dimethylformamide, N, N-dimethylacetamide, etc.), N -Methylpyrrolidone, 1,3-dimethylimidazolidinone, 3-methyloxazolidinone, esters (ethyl acetate, butyl acetate, etc.), carbonates (diethyl carbonate, ethylene carbonate, propylene carbonate, etc.), ketones (acetone, 2 − Thanong, cyclohexanone), hydrocarbons (hexane, petroleum ether, benzene, toluene, etc.) or mixed solvents thereof.

The adsorption amount of the EC dye is preferably 0.01 to 100 mmol per unit surface area (1 m ² ) of the semiconductor nanoporous layer, for example. Further, the adsorption amount of the EC dye to the semiconductor fine particles is preferably in the range of 0.01 to 100 mmol per 1 g of the semiconductor fine particles. Moreover, 0.001-2 mol / L is preferable and, as for the density | concentration in electrolyte of EC pigment | dye, 0.005-1 mol / L is more preferable.
Therefore, the EC dye is included in the semiconductor nanoporous layer is intended to include the case where the EC dye is applied to the surface of the semiconductor nanoporous layer.
Of course, the EC dye of the present invention is not necessarily included in the semiconductor nanoporous layer, and may be included in other layers as long as it does not depart from the spirit of the present invention.

(Charge transfer agent)
Like the EC dye, the charge transfer agent is supported on the surface and inside of the semiconductor nanoporous layer and contained in a state of being dissolved or dispersed in the electrolyte layer or the semiconductor nanoporous layer. preferable. The charge transfer agent can be supported on the semiconductor nanoporous layer by the same method as for EC dyes. By using the charge transfer agent and the EC dye in combination, a redox reaction proceeds smoothly due to the color-adding effect by the simultaneous color development of both, and the interaction between the two, and the color development efficiency is further improved.

  The charge transfer agent is not particularly limited and may be appropriately selected depending on the intended purpose. However, those exhibiting electrochromic properties are suitable, and examples thereof include hydrazone and phenothiazine. It can use individually or in combination of 2 or more types.

The amount of adsorption of the charge transfer agent is preferably 0.01 to 100 mmol per unit surface area (1 m ² ) of the semiconductor nanoporous layer, for example. The amount of charge transfer agent adsorbed on the semiconductor fine particles is preferably in the range of 0.01 to 100 mmol per gram of semiconductor fine particles. The concentration of the charge transfer agent in the electrolyte is preferably 0.001 to 2 mol / L, and more preferably 0.005 to 1 mol / L.

(Electrolyte layer)
The electrolyte layer is not particularly limited and can be appropriately selected depending on the purpose, but preferably contains an EC dye and / or a charge transfer agent, and the EC dye and the charge transfer agent include those described above. However, it is preferable to use the same EC dye or charge transfer agent supported on the semiconductor nanoporous layer. The electrolyte layer may be any of (1) liquid, (2) solid, and (3) gel.

(1) In the case of a liquid electrolyte layer, when the electrolyte layer is a liquid, it includes redox pairs (redox couples) such as I− / I ³⁻ , Br ⁻ / Br ³⁻ , quinone / hydroquinone pairs, It is preferable to use a charge transporting substance such as an electrolyte that can be transported at a sufficient speed in a solvent.

Examples of the electrolyte include iodine, bromine, LiI, NaI, KI, CsI, CaI ₂ , LiBr, NaBr, KBr, CsBr, CaBr _{2 and} other metal halides, tetraethylammonium iodide, tetrapropylammonium iodide, iodine Halogenated salts of ammonium compounds such as tetrabutylammonium bromide, tetramethylammonium bromide, tetraethylammonium bromide and tetrabutylammonium bromide, alkyl viologens such as methyl viologen chloride and hexyl viologen bromide, polyhydroxy such as hydroquinone and naphthohydroquinone At least one of iron complexes such as benzene, ferrocene, and ferrocyanate can be used, but is not limited thereto. In addition, when a plurality of electrolytes that generate redox pairs (redox couples) in advance are used, such as a combination of iodine and lithium iodide, it is possible to improve the performance of EC display elements, particularly current characteristics. It becomes. Among these, a combination of iodine and an ammonium compound, iodine and a metal iodide, and the like are preferable.

  Solvents for dissolving these electrolytes include carbonate compounds such as ethylene carbonate and propylene carbonate, ethers such as dioxane, diethyl ether and ethylene glycol dialkyl ether, methanol, ethanol, isopropyl alcohol, ethylene glycol, propylene glycol, polyethylene glycol and the like Alcohols, nitriles such as acetonitrile and benzonitrile, aprotic polar solvents such as dimethylformamide, dimethyl sulfoxide, propylene carbonate and ethylene carbonate, water, and the like can be used, but are not limited thereto.

  The electrolyte concentration of the electrolyte in the solvent is preferably 0.001 to 2 mol / L, and more preferably 0.005 to 1 mol / L. By setting the electrolyte concentration to 0.001 mol / L or more, the function as a carrier can be more effectively maintained and the characteristics can be sufficiently maintained. On the other hand, by setting it to 2 mol / L or less, the function as a carrier can be maintained more effectively, the viscosity of the electrolyte solution can be prevented from becoming too high, and a decrease in current can be more effectively suppressed.

(2) In the case of a solid electrolyte layer When the electrolyte layer is solid, it may be any substance exhibiting ionic conductivity or electronic conductivity, for example, AgBr, AgI, CuCl, CuBr, CuI, LiI. _{, LiBr, LiCl, LiAlCl 4,} LiAlF 4, halides _{etc., AgSBr, C 5 H 5 NHAg} 5 I 6, Rb 4 Cu1 6 I 7 Cl 13, Rb 3 Cu 7 Cl 10 and the like of the inorganic Fukushio, LiN, Lithium nitride such as Li ₅ NI ₂ , Li ₆ NBr ₃ and derivatives thereof, lithium oxyacid salts such as Li ₂ SO ₄ , Li ₄ SiO ₄ , Li ₃ PO ₄ , ZrO ₂ , CaO, Gd ₂ O ₃ , HfO ₂ , Y ₂ O ₃ , Nb ₂ O ₅ , WO ₃ , Bi ₂ O ₃ , oxides such as these solid solutions, CaF ₂ , PbF ₂ , SrF ₂ , LaF ₃ , TISn ₂ F ₅ , CeF _3, etc. Fluoride, Cu Chalcogenides such as ₂ S, Ag ₂ S, Cu ₂ Se, AgCrSe ₂ , polymers containing perfluorosulfonic acid in vinyl fluoride polymers (for example, Nafion), polythiophene, polyaniline, polypyrrole as organic charge transport materials And the like, aromatic amine compounds such as triphenylamine, carbazole compounds such as polyvinyl carbazole, and silane compounds such as polymethylphenylsilane are not limited thereto.

(3) In the case of a gel electrolyte layer, when the electrolyte layer is in a gel form, polymer addition, oil gelling agent addition, and polyfunctional monomers can be mixed and used in the electrolyte and the solvent. In the case of gelation by adding the polymer, compounds described in “Polymer Electrolyte Reviews-1 and 2” (JRMacCallum and CAVincent co-edit, ELSEVIER APPLIED SCIENCE) can be used. Acrylonitrile, polyvinylidene fluoride, and the like are preferable. When gelation is performed by adding the oil gelling agent, “J. Chem Soc. Japan, Ind. Chem. Sec., 46, 779 (1943)”, “J. Am. Chem. Soc., 111, 5542 (1989) ], "J. Chem. Soc., Chem. Commun., 1993, 390", "Angew. Chem. Int. Ed. Engl., 35, 1949 (1996)", "Chem. Lett., 1996, 885". "," J. Chem. Soc., Chem. Commun., 1997, 545 "and the like can be used. In particular, compounds having an amide structure in the molecular structure are preferred.

(4) A solid electrolyte layer formed by polymerizing a mixed solution of a matrix material and a supporting electrolyte to form a film can also be used.

-Supporting electrolyte-
There is no restriction | limiting in particular as said supporting electrolyte, According to the objective, it can select suitably, An inorganic electrolyte may be sufficient and an organic electrolyte may be sufficient. These may be used individually by 1 type, may use 2 or more types together, may be a commercial item, and may synthesize | combine suitably.

  Examples of the inorganic electrolyte include inorganic acid anions-alkali metal salts, alkali metal salts, alkaline earth metals, etc. Among these, inorganic acid anions-alkali metal salts are preferable, and inorganic acid lithium salts are more preferable. preferable.

Examples of the inorganic acid anion-alkali metal salt include XAsF ₆ , XPF ₆ , XBF ₄ , XClO ₄ , etc. (where X represents H, Li, K, or Na). Specifically, lithium perchlorate and the like are preferable.

Examples of the alkali metal salt include LiI, KI, LiCF ₃ SO ₃ , LiPF ₆ , LiClO ₄ , LiBF ₄ , LiSCN, LiAsF ₆ , NaCF ₃ SO ₃ , NaPF ₆ , NaClO ₄ , NaI, NaBF ₄ , NaAsF _6. , KCF ₆ SO ₃ , KPF ₆ , and the like.

  Examples of the organic electrolyte include organic acid anion-alkali metal salts, quaternary ammonium salts, anionic surfactants, imidazolium salts, etc. Among these, organic acid anions-alkali metal salts are preferable. An organic acid lithium salt is more preferable.

Examples of the organic acid anion-alkali metal salt include XCF ₃ SO ₃ , XCnF _{2n + 1} SO ₃ (n = 1 to 3), XN (CF ₃ SO ₂ ) ₂ , XC (CF ₃ SO ₂ ) ₃ , XB (CH ₃ ) ₄ , XB (C ₆ H ₅ ) ₄ , etc. (in which X represents H, Li, K or Na), specifically, polylithium methacrylate, etc. Are preferable.

Examples of the quaternary ammonium salt include [CH ₃ (CH ₂ ) ₃ ] ₄ N · Y, C _n H _{2n + 1} N (CH ₃ ) ₃ · Y (n = 10 to 18), (C _n H _{2n + 1} ) ₂ N (CH ₃ ) ₂ · Y (n = 10 to 18), etc. (in which Y represents BF ₄ , PF ₆ , ClO ₄ , F, Cl, Br or OH). To express.)

Examples of the anionic surfactant include CnH _{2n + 1} COO · X (n = 10 to 18), C _n H _{2n + 1} OC _m H _2m COO · X (n = 10 to 18, m = 10 to 10). 18), C ₁₀ H ₇ COO · X, C _n H _{2n + 1} C ₁₀ H ₆ COO · X (n = 10 to 18), C _n H _{2n + 1} SO ₃ · X (n = 10 to 18), _{C n H 2n + 1 OC m} H 2m SO 3 · X (n = 10~18, m = 10~18), C 10 H 7 SO 8 · X, C n H 2n + 1 C 10 H 6 SO 3 · X (n = 10~18), C n H 2n + 1 OSO 3 · X (n = 10~18), and the like (however, in these X represents H, Li, K or Na.) .

  In particular, the supporting electrolyte preferably contains an inorganic acid lithium salt and an organic acid lithium salt.

-Matrix material-
There is no restriction | limiting in particular as said matrix material, According to the objective, it can select suitably, For example, the high molecular compound which has a hetero atom, etc. are mentioned.

  Examples of the polymer compound having a hetero atom include a polymer compound having an oxygen atom, a polymer compound having a nitrogen atom, a polymer compound having a sulfur atom, and a polymer compound having a halogen atom.

Examples of the polymer compound having an oxygen atom include R ¹ — (OCH ₂ CH ₂ ) _n O—R ^2, where n represents an integer, and R ¹ represents an ethylene group, a styrene group, a propylene group, or a butene group. Represents a butadiene group, a vinyl chloride group, a vinyl acetate group, an acrylic acid group, a methyl acrylate group, a methacrylic acid group, a methyl methacrylate group, a methyl vinyl ketone group, an acrylamide group or the like, and R ² represents H, CH ₃ or And a compound represented by R ^1. ), Specifically, polyethylene glycol, polypropylene glycol, non-polyethers (for example, poly (3-hydroxypropionic acid), polyvinyl acetate), Etc. are preferable.

Examples of the polymer compound having a nitrogen atom include R ¹ — (NHCH ₂ CH ₂ ) _n NH—R ² (n represents an integer, and R ¹ represents an ethylene group, a styrene group, a propylene group, or a butene group. Represents a butadiene group, a vinyl chloride group, a vinyl acetate group, an acrylic acid group, a methyl acrylate group, a methacrylic acid group, a methyl methacrylate group, a methyl vinyl ketone group, an acrylamide group or the like, and R ² represents H, CH ₃ or R ¹ represents a compound represented by R ¹ ), and specific examples thereof include polyethyleneimine, poly-N-methylethyleneimine, polyacrylonitrile, and the like.

Examples of the polymer compound having a sulfur atom include R ¹ — (SCH ₂ CH ₂ ) _n S—R ² (n represents an integer, and R ¹ represents an ethylene group, a styrene group, a propylene group, or a butene group. Represents a butadiene group, a vinyl chloride group, a vinyl acetate group, an acrylic acid group, a methyl acrylate group, a methacrylic acid group, a methyl methacrylate group, a methyl vinyl ketone group, an acrylamide group or the like, and R ² represents H, CH ₃ or R ¹ represents a compound represented by R ¹ ), and specific examples thereof include polyalkylene sulfides.

  The molecular weight of the matrix material is not particularly limited and can be appropriately selected according to the purpose.However, since the lower one often has fluidity at room temperature, the lower one is preferable from the viewpoint of film forming property. The number average molecular weight is preferably 1000 or less.

  The amount of the matrix material used in the electrolyte layer is preferably such that the molar ratio to the supporting electrolyte (matrix material: supporting electrolyte) is 70:30 to 5:95, and is 50:50 to 10:90. More preferably, it is particularly preferably 50:50 to 20:80.

  The molar ratio means the ratio between the molar amount of the matrix material and the molar amount of ions of the supporting electrolyte. The molar amount of the matrix material means a molar amount in which the monomer unit of the polymer compound is converted into one molecule.

<Board>
As the substrate used in the present invention, a plastic substrate, a glass substrate, paper, a metal substrate, and the like are used. However, a transparent substrate is preferable because a structural unit is laminated, and a transparent plastic substrate or glass substrate is preferable. It is. In particular, in the present invention, since a TFT is formed on a substrate, a glass substrate is more preferable from the viewpoint of heat resistance.
Examples of the plastic substrate include triacetyl cellulose (TAC), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), syndiotactic polystyrene (SPS), polyphenylene sulfide (PPS), polycarbonate (PC), and polyarylate. (PAr), polysulfone (PSF), polyester sulfone (PES), polyetherimide (PEI), cyclic polyolefin, polyimide (PI) and the like. Polyethylene terephthalate (PET) is preferable.

The thickness of the substrate in the present invention is not particularly defined, but is preferably 30 μm to 700 μm, more preferably 40 μm to 200 μm, and still more preferably 50 μm to 150 μm.
Further, the haze of the substrate is preferably 3% or less, more preferably 2% or less, further preferably 1% or less, and the total light transmittance is preferably 70% or more, more preferably 80% or more, and still more preferably 90%. % Or more. The haze is measured by a haze meter (for example, manufactured by Nippon Denshoku Industries Co., Ltd.), and the total light transmittance is measured by visible / ultraviolet absorption spectroscopy.

  In the case of a reflective optical element, a non-transparent non-light transmissive substrate can be used as the substrate farthest from the viewing direction. As the non-light transmissive substrate, a white support having light reflectivity can be used. Examples of the white support include a plastic substrate to which an inorganic pigment such as titanium oxide or zinc oxide is added.

<Electrochromic display element>
Below, the structure of the electrochromic display element (EC display element) of this invention is demonstrated.
An EC display element according to the present invention includes an electrochromic layer containing at least one electrochromic dye and an electrolyte, at least one transparent thin film transistor, and a transparent pixel electrode arranged in a matrix on a substrate. And a plurality of structural units each having a transparent counter electrode. The EC display element of the present invention may include other structural units as long as it has at least two or more of the above structural units. For example, in the case of a reflective optical element, a non-light transmissive electrode may be used as described above in the structural unit arranged on the side farthest from the viewing direction, and the substrate is also non-light transmissive. It may be of sex. Moreover, you may have a structural unit which has an electrochromic layer which does not contain electrolyte.
In particular, the electrochromic display element of the present invention is formed by laminating at least three structural units, and the electrochromic layers contained in the three structural units are each independently an electrochromic dye of yellow, cyan, or magenta. It is preferable to display a color image containing. As described above, in the case of a display element in which the structural units are stacked in the vertical direction, a method for expressing a color image is based on the same principle as that for a halftone dot of a printed material. The stacking order of yellow, cyan, or magenta is preferably magenta, yellow, cyan from the front of the viewing direction.

An example of the EC display element of the present invention is shown in FIG. FIG. 2 is a schematic cross-sectional view showing the configuration of the EC display element of the present invention.
In the EC display element of FIG. 2, a counter electrode (transparent electrode) 321 is provided on the surface of the substrate 301, and a semiconductor nanoporous layer 341 is further provided on the surface of the counter electrode (transparent electrode) 321. On the surface of the substrate 303, a pixel electrode (transparent electrode) 361 and a thin film transistor (TFT) 10 are arranged for each pixel, and the pixel electrodes (transparent electrode) 361 are arranged in a matrix. An electrolyte layer 381 is interposed between the pixel electrode (transparent electrode) 361 or the thin film transistor (TFT) 10 and the semiconductor nanoporous layer 341. In order to control the thickness of the electrochromic layer, the electrolyte layer 381 may be provided with a spacer or a support (resin structure) (not shown). As the spacer and the resin structure, known ones can be appropriately selected and applied. The distance between the counter electrode (transparent electrode) 321 and the pixel electrode (transparent electrode) 361 is preferably 0.01 mm to 1 mm, and more preferably 0.1 mm to 0.5 mm. If it is narrower than 0.01 mm, it becomes easy to energize, so that the display performance tends to deteriorate, and if it is wider than 1 mm, the driving voltage increases.

In the EC display element of FIG. 2, three such structural units are stacked to have structural units 401, 403, and 405. A scattering white reflective layer 50 is provided outside the structural unit 405 farthest from the viewing side, and a substrate 307 is further provided outside.
Since the EC display element of the present invention has a TFT for each structural unit, it is not necessary to make electrical connection with a contact hole or the like in the vertical direction, and the manufacture is simple.

FIG. 3 is an enlarged view of the structural unit 40 shown in FIG. The state in which the semiconductor nanoporous layer 34 carries the EC dye 60 contained in the electrolyte layer 38 is shown.
1 and 2 show the case where the semiconductor nanoporous layer 34 is a single layer, the semiconductor nanoporous layer 34 having a two-layer structure or a multilayer structure may be provided.
Further, although the positions of the thin film transistors in the same pixel are shown as overlapping positions when viewed from the viewing direction, the positions of the thin film transistors may be shifted. As described above, although the thin film transistor is transparent, the light transmittance in the portion where the thin film transistor is formed tends to be lower than that in the portion where the thin film transistor is not formed, and the EC layer has a height corresponding to the height of the thin film transistor. Since the thickness is reduced, the color density tends to decrease. Therefore, by shifting the position of the thin film transistor of the same pixel, it is possible to suppress uneven brightness of the display screen as compared with the case where the thin film transistors of the same pixel are arranged at positions overlapping each other.
Further, although the scattering white reflection layer 50 is provided in FIG. 1, the scattering white reflection layer 50 is not provided, and the substrate 307 farthest from the viewing side may be a white substrate having light reflectivity. In addition, after providing the scattering white reflection layer 50, the substrate 307 may be a white substrate having light reflectivity.

FIG. 4 shows a schematic plan view of the electrochromic device of the present invention.
In the electrochromic element, pixel electrodes (transparent electrodes) 36 are arranged in a matrix for each pixel in order to perform active matrix driving. In addition, in order to apply a voltage to each pixel electrode 36, a thin film transistor TFT10, and a gate line 72 and a source line 74 for driving the thin film transistor 10 are formed.

  2 to 4, the voltage is applied between the counter electrode (transparent electrode) 32 and the pixel electrode (transparent electrode) 36 to extinguish the EC dye 60 carried on the semiconductor nanoporous layer. It is what makes it color. In the multilayer EC display element of the present invention, a vertical electric field substantially perpendicular to the substrate surface is applied to the electrochromic layer. A voltage is applied to the pixel electrode of the pixel to be driven through the thin film transistor 10 connected thereto. The voltage for forming an image is not particularly limited and may be appropriately selected depending on the intended purpose. For example, about 0.5 to 10 V is preferable, and about 1 to 5 V is more preferable.

  As described above, by driving each pixel in an active matrix, the electrochromic dye contained in each electrochromic layer is colored and decolored, and full color display can be performed.

The thin film transistor 10 used for the electrochromic display element of the present invention described above is transparent, and the aperture ratio can be increased.
Further, when a homologous compound single crystal InMO ₃ (ZnO) _m thin film is used as the semiconductor active layer of the thin film transistor 10, defects are less likely to be present at the interface between the gate and the active layer, gate leakage current is reduced, and stable active matrix driving is achieved. It can be performed. In addition, since the band gap energy of the homologous compound single crystal InMO ₃ (ZnO) _m is larger than 3.3 eV, it is transparent to visible light having a wavelength of 400 nm or more, and generation of a photo-induced current due to visible light is eliminated. As a result, since the thin film transistor 10 does not malfunction even when visible light is incident, it is not necessary to provide a light blocking layer such as a black matrix mask on the thin film transistor 10, so that the aperture ratio can be improved and bright display can be performed. Furthermore, since the homologous compound single crystal InMO ₃ (ZnO) _m thin film is a good insulator near room temperature, it has normally-off operation, good switching characteristics, and is stable up to a high temperature of about 1000 ° C. Since the carrier mobility is 10 times higher than that of amorphous silicon, it can be expected to operate at high speed.

  The EC display element of the present invention varies depending on the application, but in the case of a transmissive element, the response speed until reaching the ultimate transmittance is preferably 100 msec or less, and more preferably 10 msec or less. In the case of a reflective element, the response speed until reaching the ultimate absorbance is preferably 100 msec or less, and more preferably 10 msec or less.

<Application>
The EC display element of the present invention can be suitably used in various fields, such as a light control element such as an ECD (Electrochromic Display), a large display board, an antiglare mirror, and a light control glass, a touch panel key switch, etc. It can be suitably used for a low voltage drive element, an aperture device, an optical switch, an optical memory, electronic paper, an electronic album, and the like.

  The present invention will be described more specifically with reference to the following examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below.

[Example 1]
A reflective display element shown in FIG. 2 was produced. Details of the manufacturing method will be described.

<Production of support>
Conductive tin dioxide was attached to a 1 mm-thick glass substrate (trade name Corning 1737, manufactured by Corning) by vapor deposition to prepare a support.

<Preparation of electrochromic layer>
1) Preparation of semiconductor particles
In accordance with the production method described in the paper by CJBarbe et al., J. Am. Ceramic Soc. 80, p3157, titanium tetraisopropoxide is used as a titanium raw material, and the temperature of the polymerization reaction in an autoclave is set to 230 ° C. A dispersion of anatase-type titanium dioxide having a titanium concentration of 11% by mass was synthesized. The primary particle size of the obtained titanium dioxide particles was 10 to 30 nm. The obtained dispersion was applied to an ultracentrifuge to separate the particles, and the agglomerates were dried, and then pulverized on an agate mortar to obtain a white powder.

2) Preparation of porous semiconductor fine particle layer The semiconductor fine particle of 1) above was added to a mixed solvent consisting of water and acetonitrile in a volume ratio of 4: 1 at a concentration of 32 g per 100 ml of solvent, and a rotating / revolving mixing conditioner was prepared. The resulting mixture was uniformly dispersed and mixed to obtain a porous semiconductor fine particle layer coating solution. As a result, the obtained white dispersion becomes a high-viscosity paste of 500 to 1500 P (= 50 to 150 N · s / m ² ), and has liquid properties suitable for use as it is. all right.
The porous semiconductor fine particle layer coating solution is applied to the support coated with the conductive tin dioxide film with a uniform liquid thickness of 40 to 70 μm using an applicator, and the coating layer is dried at room temperature for about 1 hour. I let you. Furthermore, after the coating layer was dried at 120 ° C. for 30 minutes, it was exposed to UV light from a 100 W mercury lamp ultraviolet light source for 30 minutes to perform post-treatment. In this way, a porous semiconductor fine particle layer was produced.

3) Adsorption of EC dye Next, 0.02M of 2- {2- [4- (dimethylamino) phenyl] ethenyl} -3,3 as an EC dye was applied to the porous semiconductor fine particle layer prepared in 2) above. -Dilute-5-phosphonoindolino [2,1-b] oxazoline was immersed in an acetonitrile solution, dye adsorption treatment was performed, and a part 1 that developed a yellow color was produced. Same as Part 1, except that the EC dye was 0.02M 2- {2- [4- (dimethylamino) phenyl] -1,3-butadienyl} -3,3-dimethyl-5-carboxyindolino, respectively. [2,1-b] oxazoline or 0.02M 2- {2- [4- (methoxy) phenyl] -1,3,5-hexatrienyl} -3,3-dimethyl-5-phosphonoindo In place of Reno [2,1-b], a part 2 that develops magenta and a part 3 that develops cyan are produced.

<Production of transparent transistor>
(Preparation of single crystal InGaO ₃ (ZnO) ₅ thin film)
A patterned ZnO thin film having a thickness of 2 nm was epitaxially grown on a glass substrate at a substrate temperature of 700 degrees by a PLD method through a mask. Next, the substrate temperature was cooled to room temperature, and a polycrystalline InGaO ₃ (ZnO) ₅ thin film having a thickness of 150 nm was deposited on the ZnO epitaxial thin film by the PLD method. The two-layer film produced in this way was taken out into the atmosphere, subjected to a heat diffusion treatment in the atmosphere at 1400 degrees for 30 minutes using an electric furnace, and then cooled to room temperature.

(Preparation of MISFET device)
A top gate type MISFET device was fabricated by photolithography. ITO and amorphous Al ₂ O ₃ were used for the source and drain electrodes and the gate insulating film, respectively. The channel length and channel width were 0.05 mm and 0.2 mm, respectively.

(Installation of insulation film)
A polyimide film (thickness 10 μm, manufactured by Nissan Chemical Co., Ltd.) was installed as an insulating film on the transparent transistor by coating.

<EC display element>
The EC display element was assembled by superimposing three pairs of yellow, magenta, and cyan on the EC layer side of parts 1 to 3 and the electrode substrate provided with the transparent transistor. Here, the distance between each electrode was 0.2 mm. A 0.2M tetrabutylammonium perchlorate propylene carbonate solution was used as the electrolyte solution. In addition, the magnitude | size of the produced pair electrode was 5 mm x 5 mm. A pair of electrodes in the obtained EC display element was connected with lead wires (a dye-coupled electrode on the anode and a transparent transistor electrode substrate on the cathode) to produce a display device.

<Evaluation of display element>
In this display device, when a voltage of 3 V was applied to the magenta coloring structural unit (part 2) at room temperature, the styryl derivative was oxidized at the anode and changed from colorless to magenta. Next, when a voltage of 3 V was applied to the cyan color developing structural unit (part 3) at room temperature, the styryl derivative was oxidized at the anode and changed from colorless to cyan. Further, when a voltage of 3 V was applied to the yellow coloring structural unit (part 1) at room temperature, the styryl derivative was oxidized at the anode and changed from colorless to yellow.

  Further, when a voltage of 3 V was applied simultaneously to the magenta color structural unit and the cyan color structural unit at room temperature, the styryl derivative was oxidized at the anode of each structural unit and colored to magenta and cyan. Changed. Next, when a voltage of 3 V was simultaneously applied to the magenta coloring unit and the yellow coloring unit at room temperature, the styryl derivative was oxidized at the anode of each structural unit to develop magenta and yellow. It turned red. In addition, when a voltage of 3 V was applied simultaneously to the cyan color developing unit and the yellow color developing unit at room temperature, the styryl derivative was oxidized at the anode of each structural unit to develop cyan and yellow, and the whole was colorless to green. Changed.

  Furthermore, when a voltage of 3 V was simultaneously applied to the three colored structural units at room temperature, the styryl derivative was oxidized at the anode of each structural unit and colored to magenta, cyan, and yellow, and the whole changed from colorless to black. did.

Note that the response speed until reaching the reached transmittance was 80 msec in all cases. Even after the voltage application was stopped, color development continued for over 600 seconds. In addition, even when the color development / decoloration was repeated 10,000 times, the color density during color development and the transparency during color erasure hardly changed.
Note that the aperture ratio of the obtained element was 95% and the reflectance was 60%, so that a very bright display was possible.

[Comparative Example 1]
A comparative electrochromic display element was produced in the same manner as in Example 1 except that the transparent thin film transistor having the InGaO ₃ (ZnO) ₅ thin film was replaced with the following nontransparent transistor.

(Production of comparative transistor)
The semiconductor active layer was prepared by vapor-depositing morphous silicon, and a black matrix using carbon black was attached on top of the thin film transistor.

  Since the comparative electrochromic display element obtained had a smaller aperture ratio than the electrochromic display element of the present invention of Example 1, the reflectance of the element was lowered.

[Example 2]
In Example 1, an EC display element was produced in the same manner as in Example 1 except that the following ZnO / SnO ₂ mixed porous semiconductor fine particle layer was used instead of the titanium oxide porous semiconductor fine particle layer.

(ZnO / SnO ₂ mixed porous semiconductor fine particle layer)
Acetic acid (0.3 ml) was added dropwise to 1.5 ml of a 15 mass% SnO ₂ colloidal aqueous solution (particle size: 15 nm), and 0.3 g of ZnO powder (particle size: 0.2 μm) and 20 ml of methanol were slightly added to the gel solution mixed well in a mortar. Add one by one and mix well. Further, 0.2 ml of Triton X-100 was added and mixed well, and this was masked to 0.5 × 0.5 cm ² on two fluorine-doped tin oxide conductive film glass (FTO) electrodes with a hot plate (100 To 120 ° C) and fired at 550 ° C to form a ZnO / SnO ₂ mixed porous membrane electrode. When the fine structure of the film was examined by SEM observation, the ZnO and SnO ₂ particles were not aggregated separately, but SnO ₂ fine particles were adhered to surround the periphery of ZnO having a large particle diameter. The specific surface area of the fired product film (transparent conductive film) was 100 g / cm ² . The specific surface area was measured by a method of adsorbing nitrogen gas at a liquid nitrogen temperature using a BET surface area measuring device (manufactured by Mitsuwa Richemical Co., Ltd., Multi Soap 12).

(Evaluation of display performance)
When the display performance of the obtained EC display element was evaluated in the same manner as in Example 1, the response speed until reaching the ultimate transmittance was 80 msec in all cases. Even when the voltage application was stopped, color development continued for 600 seconds or more. In addition, even when the color development / decoloration was repeated 10,000 times, the color density during color development and the transparency during color erasure hardly changed.

It is a cross-sectional schematic diagram which shows the structure of the transparent thin-film transistor concerning this invention. It is a cross-sectional schematic diagram which shows the structure of an example of the electrochromic display element of this invention. It is the figure which expanded a part of electrochromic display element of this invention. It is a plane schematic diagram showing the composition of an example of the electrochromic display element of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Thin-film transistor 12 Semiconductor active layer 301,303,305,307 Substrate 34,341,343,345 Semiconductor nanoporous layer 36,361,363,365 Pixel electrode 38,381,383,385 Electrolyte layer 40,401,403, 405 Structural unit 60 Electrochromic dye (EC dye)

Claims (9)

On a substrate, an electrochromic layer including at least one electrochromic dye and an electrolyte, at least one transparent thin film transistor, a transparent pixel electrode arranged in a matrix, a transparent counter electrode, Ri Na by stacking a plurality of structural units comprising a,
The thin film transistor is homologous compound InMO ₃ (ZnO) _{m (M} is an In, Fe, Ga, or an Al, m represents. An integer of 1 or more and less than 50) the Rukoto to have a thin film A characteristic electrochromic display element.   The at least three structural units are laminated, and the electrochromic layers included in the three structural units each independently contain a yellow, cyan, or magenta electrochromic dye. 2. The electrochromic display element according to 1.   3. The electrochromic display element according to claim 2, wherein electrochromic layers each containing the magenta, yellow, and cyan electrochromic dyes are laminated in order from the side closer to the viewing side. Wherein the surface of the counter electrode, electrochromic display element according to any one of claims 1 to 3, characterized by comprising a semiconductor nanoporous layer as one of the electrochromic layer. The electrochromic dye is reversibly developed or decolored by at least one of an electrochemical oxidation reaction and a reduction reaction, and the electrochromic dye is supported on the semiconductor nanoporous layer,
The electrochromic display element according to claim 4 , further comprising an electrolyte layer between the semiconductor nanoporous layer and the pixel electrode. The electrochromic display element according to claim 5 , wherein the electrolyte layer contains a charge transfer agent. The semiconductor nanoporous layer includes semiconductor fine particles, and the semiconductor fine particles are at least one selected from the group consisting of a single semiconductor, an oxide semiconductor, a compound semiconductor, an organic semiconductor, a complex oxide semiconductor, and a mixture thereof. The electrochromic display element according to any one of claims 4 to 6 , wherein the electrochromic display element is provided. The semiconductor fine particles are SnO ₂ —ZnO, Nb ₂ O ₅ —SrTiO ₃ , Nb ₂ O ₅ —Ta ₂ O ₅ , Nb ₂ O ₅ —ZrO ₂ , Nb ₂ O ₅ —TiO ₂ , Ti—SnO ₂ , Zr. The electrochromic display element according to claim 7 , wherein the electrochromic display element is at least one complex oxide semiconductor selected from the group consisting of —SnO ₂ , In—SnO _2, and Bi—SnO ₂ . The electrochromic dye, electrochromic display element according to any one of claims 1 to 8, characterized in that at least one member selected from the group consisting of organic compounds, and metal complexes.

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