JPH07175417A - Electrochromic element material and electrochromic element using the same - Google Patents

Abstract

PURPOSE:To obtain an electrochromic element having a high coloring efficiency which can be easily made into a large-size thin film by constituting the element of fine particles obtd. by hydrolysis of a metal alkoxy compd. in a medium containing water. CONSTITUTION:The electrochromic element material consists of precipitated fine particles obtd. by hydrolysis of a metal alkoxy compd. in a medium containing water, or consists of fine particles obtd. by heat treatment of the precipitated fine particles. To produce the metal alkoxy compd., a metal or metal compd. is made by reactation with an org. compd. containing hydroxy groups. If the precipitate is an oxide, the precipitate as produced is dried and then used. If the precipitated fine particles are metal hydroxide, metal hydrate, or the like, these particles are heat treated to obtain metal oxide. The heat treatment is performed by such a method to heat the particles in an electric furnace in air or a gas atmosphere. The gas used is nitrogen, chlorine or the like. The fine particles directly obtd. by precipitation or after the heat treatment consist of superfine particles having 10-100nm particle size without depending on the kind of the metal compd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrochromic device which has a high coloring efficiency and can be easily enlarged.

[0002]

2. Description of the Related Art An electrochromic device that applies electrochromism in which a color is reversibly changed by applying a current has a memory property for display, consumes less power, has no viewing angle dependency, and is suitable for large-area display. Due to the advantages such as being provided, researches on dimming elements, display elements and the like have been conducted.

An electrochromic device generally has a laminated structure in which a transparent electrode, an electrolyte and an electrochromic layer are combined. The thin film used as the electrochromic layer is formed of a transition metal compound such as tungsten oxide, a metal complex, an inorganic or organic material such as an organic dye. These thin film layers are formed by vacuum vapor deposition, sputtering, electric field film formation, chemical film formation, or the like.

Film formation by vacuum vapor deposition or sputtering requires an expensive apparatus, and it is necessary to maintain a high vacuum inside the apparatus. Further, in order to obtain an electrochromic device having high coloring efficiency, it is necessary to increase the film thickness of the electrochromic layer, and there are restrictions such as a long vapor deposition time and strict film forming conditions. These problems make it difficult to save energy and increase the area of the device. In order to form a thin film by the electric field film formation or the chemical film formation method, it is necessary to strictly control the film formation conditions, and there is a problem that raw materials and devices used are limited. Further, when a display pattern is required, special processing such as etching and mask is required.

As a chemical film forming method, for example, a method in which a tungsten oxide prepared by coating a solution of an organic tungsten compound in an organic solvent on a transparent electrode substrate and then heating it is used as an electrochromic layer ( JP-A-56-38379), a transition metal compound solution such as an alcohol solution of tungsten chloride is coated on an electrode substrate,
A method of forming an electrochromic layer by drying (JP-A-55-11207), a chlorine-based compound of tungsten is reacted with an organic acid, and then reacted with an organic solvent having a hydroxy group to synthesize an organic compound of tungsten. Then, the organic compound of the tungsten compound is supplied onto the transparent electrode substrate and then heated to form an electrochromic layer (JP-A-62-112132, JP-A-63-1).
5228, JP-A-63-15229) and the like have been reported. However, in these methods, it is difficult to control the heating temperature because the substrate is coated and then heated. It was difficult to obtain a stable electrochromic device due to differences in thermal expansion coefficient and thermal stability.

[0006]

DISCLOSURE OF THE INVENTION The present invention overcomes the drawbacks of the conventional electrochromic device, that is, the low coloring efficiency, and the difficulty in saving energy and forming a large area when forming an electrochromic layer. It was done for good.

[0007]

Means for Solving the Problems That is, the present invention is an electro-conductive method comprising precipitate fine particles obtained by hydrolyzing a metal alkoxy compound in a medium containing water, or fine particles obtained by heat-treating the precipitate fine particles. Chromic device material.

Further, the present invention relates to an electrochromic device formed by forming an electrochromic layer containing the above electrochromic device material on a transparent electrode substrate.

In the present invention, a metal alkoxy compound may be produced by reacting a metal or a metal compound with an organic compound containing a hydroxy group. When synthesizing an alkoxy compound, a hydroxy compound of a positive metal element, a strongly basic compound such as ammonia, or HOCl, (O
H) It is preferable to coexist with an acid such as ₃ PO. or,
A weakly positive metal requires a catalyst such as mercuric chloride to allow the reaction to proceed. Further, a metal compound can be used in place of the metal in the synthesis of an alkoxy compound that cannot be obtained by a direct reaction with a metal and an organic solvent containing a hydroxy group. As the metal compound, any of metal halide compounds, metal nitrate compounds, metal acetate compounds, metal sulfate compounds, metal oxalate compounds, metal acetylacetonate compounds and the like may be used, and metal chloride compounds are particularly preferable. . The reaction of chloride with alcohol is a nucleophilic substitution reaction involving two molecules, and the ease of substitution of chloride ion with alkoxide anion strongly affects the electronegativity of the metal element of chloride under nucleophilic attack. Receive. Furthermore, in order to increase the reactivity, it is effective to add a base such as ammonia, pyridine or trialkylamine.

Metal or metal compound used in the present invention
Is any substance that exhibits electrochromism
Anything is fine. For example, Ti, V, Cr, Mn, Fe,
Co, Ni, Cu, Zr, Nb, Mo, Tc, Ru, R
h, In, Sn, W, Re, Os, Ir, Pr, Sm,
Metals such as Dy, Ho, Er and Lu, or their gold
Genus compounds such as WO₃, MoO₃, IrO_X, NiO_X,
CoO_X, TiO₂, Cr ₂O₃, V₂O_Five, Ta₂O_Five, Nb
₂O_Five, InN, SnN_X, ZrNCl, etc. or those
Solid solutions of, but are not limited to
Absent. Here, X does not represent a constant numerical value, and is not limited to an integer.
Yes.

The alkoxy compound is hydrolyzed to form fine particles of metal oxide, metal hydroxide or metal hydrate precipitates. The electrochromic layer of the present invention may be any compound thereof or a mixture thereof. The particle size of the particles to be synthesized is determined by the conditions of hydrolysis with water. The hydrolysis conditions include the kind of the alkoxy derivative, the concentration of the alkoxy compound, the ratio of the alkoxy compound and water, the water temperature during the hydrolysis, the stirring efficiency, the aging time after the hydrolysis and the like.

The type of alkoxy compound depends on the type of organic solvent containing the hydroxy group used. Examples of the organic solvent having a hydroxy group include methyl alcohol, ethyl alcohol, isopropyl alcohol, n-
Alcohols such as butyl alcohol, 1,2-ethanediol, 1,2-propanediol, 2-butene-1,
Diols such as 4-diol, tetraethylene glycol, polyethylene glycol, glycerin, 1,2,6
There are, but are not limited to, triols such as hexanetriol, and cellosolves such as methoxyethanol, 2-ethoxyethanol, and phenoxyethanol. Further, the metal or metal compound may be reacted only with an organic solvent containing a hydroxy group, or may be reacted with a system in which an organic solvent containing a hydroxy group is added to an inert solvent.

The concentration of the alkoxy compound may be any, but it is preferably in the range of 0.001 to 10 mol / l. The ratio of the alkoxy compound to the water used for the hydrolysis may be any ratio as long as water is present for the hydrolysis to proceed, but it is preferable that the water content is at least the number of moles of the metal or metal compound present. The temperature at the time of hydrolysis may be any, but is preferably 10 to 100 ° C. The stirring efficiency depends on the apparatus used, but any stirring that uniformly mixes the alkoxy derivative may be used. The aging time after hydrolysis may be any time, but since hydrolysis takes place in an extremely short time, it is preferably about 10 minutes to 5 hours in order to prevent heterogeneity of the system. Hydrolysis may be carried out only with water, or water may be added to a suitable organic solvent.

The metal alkoxy compound produced as described above reacts with water to form a precipitate of a metal oxide, a metal hydroxide or a metal hydrate. When the precipitate is an oxide, it can be dried and used as it is. Precipitated fine particles such as metal hydroxide or metal hydrate can be heat-treated to obtain metal oxide. Examples of the heat treatment include a method of heating in an electric furnace in the air or a gas atmosphere, but any method may be used. The gas used may be any of nitrogen, chlorine, hydrogen, ammonia, argon, helium, etc., depending on the gas atmosphere, a metal oxide, a metal hydroxide, a part or all of a metal hydrate is a nitride, It may be replaced with chloride or the like. The fine particles directly obtained by precipitation or obtained by heat treatment are composed of ultrafine particles of 10 to 100 nm regardless of the kind of metal compound.

The electrochromic layer of the present invention is a chemical method in which a metal compound is dispersed by a physical method such as vacuum deposition or sputtering, or a metal compound alone is dispersed, or a coating liquid in which a metal or a metal compound is dispersed in a resin is applied. It is formed by the method. The electrochromic layer formed by vacuum vapor deposition or sputtering heats a metal compound in a low vacuum container of 1 Torr or less to form a thin film on a transparent electrode substrate. Resins used in chemical methods are known and include polyvinyl butyral, polyacrylates, polycarbonates, polyesters, phenoxy,
Acrylic, acrylic polyol, polyamide, urethane, epoxy, silicone, polystyrene, cellulose,
Polyvinyl chloride, vinyl chloride vinyl acetate copolymer, phenol, an inorganic resin such as a melamine resin or a siloxy resin,
A mixture of these resins may be used. Isocyanate, melamine, or the like may be added to these resins to form an electrochromic layer by heat curing, UV light or electron beam curing. The thickness of the electrochromic layer is 0.01 to
10 μm is preferable.

The dispersion solvent used in the chemical method may be a known solvent or a mixture thereof, and may be an organic solvent, an inorganic solvent, water or the like. The organic solvent may be any of alcohol type, ketone type, ether type, ester type, hydrocarbon type, halogen type and the like. Specific examples include methanol, ethanol, isopropyl alcohol, acetone, methyl ethyl ketone, diethyl ether, dipropyl ether, tetrahydrofuran, 1,4-dioxane, toluene, xylene, carbon tetrachloride and the like.
As the inorganic solvent, liquid ammonia, liquid carbon dioxide, silicone oil, acid or alkaline aqueous solution is suitable.

The electrochromic device of the present invention includes a transparent electrode, an electrolyte, an electrochromic layer, an electrochromic device having a laminated structure of transparent electrodes, or a transparent electrode, a first electrochromic layer, an electrolyte and a second electrochromic layer. , An electrochromic device including a transparent electrode is preferable, but the device structure is not limited to these. The oxidative coloring type electrochromic layer of the electrochromic element is a film in which a substance exhibiting electrochromism is oxidized to develop a color, and the reduction coloring type electrochromic layer is a film in which a substance exhibiting electrochromism is reduced to develop a color.

The electrode of the electrochromic device of the present invention is preferably a transparent electrode having a high electric conductivity such as tin oxide, indium oxide and ITO, and the substrate is a solid such as glass or resin and has a high light transmittance. Any material may be used.

As the electrolyte, a known electrolyte can be used,
Either an inorganic or organic electrolyte may be used, but a resin or a dielectric containing a solvent or a cation having a high ionic conductivity such as H, Li, K, Na or Mg is preferable. The electrolyte may be a liquid, a solid solution, or a solid, but a solid is preferable because of sealing, liquid leakage, and the like. The thickness of the electrolyte is 1 mm to 0.01
μm is preferred.

[0020]

EXAMPLES The present invention will be specifically described with reference to the following examples. However, the present invention is not limited to the following examples.

Example 1 500 ml of isopropyl alcohol and 20 g of nickel chloride were placed in a beaker and stirred. After adding 150 ml of 28% aqueous ammonia, the mixture was filtered to obtain a purple-white precipitate. 200m of this precipitate is isopropyl alcohol
Pour in 1 and stir. Hydrolysis was completed by adding 4 liters of water thereto. The green-white precipitate thus obtained was filtered and dried to obtain 13.8 g of fine particle powder. As a result of instrumental analysis of this powder, it was found to be nickel hydroxide. This nickel hydroxide 10.0 g was heated at 400 ° C. for 2 hours in the air atmosphere to obtain nickel oxide 7.8 g. The particle diameter of the nickel oxide fine particles obtained by the above method is 0.02 μ
It was m.

Dispersion medium consisting of 2.0 g of nickel oxide fine particles, 10 ml of methyl ethyl ketone, xylene: butyl acetate: acrylic polyol = 1: 1: 1 (weight ratio).
6 g was put in a ball mill and dispersed for 24 hours to prepare a dispersion liquid. Next, the above dispersion liquid was spun on a transparent ITO glass electrode of 10 Ω / cm ² at 2000 r
It was applied by pm to obtain a thin film of 0.2 μm. This coating 5
An electrochromic layer was obtained by drying at 0 ° C. for 6 hours.
The haze ratio of this layer was 1%, and it was found that the transparency was high. Furthermore, using 1N KOH as the electrolyte, +1
The electrochromic film to which V was applied for 30 seconds showed an extremely dark brown color, and the transmittance at 600 nm was 10.5%.
Met. The electrochromic layer to which -1 V was applied for 1 minute had extremely high transmittance, and the transmittance at 600 nm was 87.2%.

The electrochromic layer thus obtained was used as a first electrochromic layer, and an ITO electrode of 10 Ω / cm ² was used as a second electrochromic layer. After sandwiching the two electrochromic layers with a spacer and adhering them with an epoxy resin, a 0.1 N KOH aqueous solution was injected between the electrochromic layer and the counter electrode to prepare an electrochromic element as an electrolyte. As a result of examining the coloring and decoloring response of the obtained electrochromic device, it is found that the transmittance changes from 15% to 70% in 15 seconds, and the responsiveness is good. From the measurement result of the cyclic voltammogram, the injected charge amount of this electrochromic device was 8 mC / cm ^2.
It was a good result.

Example 2 The first electrochromic layer was formed by vacuum evaporation method 1
Except for forming by vacuum of 0 ^{over 5} Toor was prepared an electrochromic device in the same manner as in Example 1. In this electrochromic device, the transmittance changed from 15% to 70% for 18 seconds, and from the measurement result of the cyclic voltammogram, the injected charge amount was 4 mC / cm ² , and a good result was obtained.

Example 3 An electrochromic device was produced in the same manner as in Example 1 except that the first electrochromic layer was formed of nickel oxide fine particles dispersed without the acrylic polyol resin. In this electrochromic device, it took 23 seconds for the transmittance to change from 15% to 70%, and the injected charge amount was 5 mC from the cyclic voltammogram measurement results.
/ Cm ² , which was a good result.

Example 4 500 ml of isopropyl alcohol and 4 g of tungsten hexachloride were placed in a beaker and stirred. After adding 150 ml of 28% aqueous ammonia, the mixture was filtered to obtain a purple-white precipitate. This precipitate was added to isopropyl alcohol 20
Add to 0 ml and stir. Hydrolysis was completed by adding 4 liters of water thereto. The green-white precipitate obtained was filtered and dried to obtain 3.3 g of fine particle powder. As a result of instrumental analysis of this powder, it was found to be tungsten hydroxide. 400 g of this tungsten hydroxide in an air atmosphere
The mixture was heated at ℃ for 2 hours to obtain 2.2 g of tungsten trioxide. The particle size of the tungsten trioxide fine particles obtained by the above method was 0.025 μm.

An electrochromic device was prepared in the same manner as in Example 1 except that the tungsten trioxide fine particles prepared in this Example as the second electrochromic layer were propylene carbonate containing 1M lithium perchlorate as an electrolyte. Was produced. This electrochromic device has a transmittance of 1% even if it changes from 15% to 70%.
From the measurement result of the cyclic voltammogram for 2 seconds, the injected charge amount was 10 mC / cm ² , and a good result was obtained.

Example 5 In a beaker, 500 ml of n-butyl alcohol, tetrasalt
Add 10 g of titanium oxide and stir. 28% ammonia water
(150 ml) was added dropwise, and after filtration, isopropyl alcohol was added.
Place in 200 ml of coal and stir. 4 l of water in it
Was added dropwise to complete the hydrolysis. The green-white precipitate obtained
The starch was filtered and dried to obtain 7.9 g of fine particle powder.
As a result of instrumental analysis of this powder, it was found to be titanium hydroxide.
7.0 g of this titanium hydroxide was added to 400 g in the atmosphere.
After heating at ℃ for 2 hours, 5.2 g of titanium oxide was obtained. that's all
The particle size of the titanium oxide fine particles obtained by the method is 0.0
It was 2 μm. True to the first electrochromic layer
Example 1 was repeated except that the titanium oxide fine particles of the example were used.
An electrochromic device was produced by the same method. Book
The electrochromic device has a transmittance of 15% to 70%.
35 seconds to change to%, cyclic volta mole
Injected charge amount is 3 mC / cm ²And
And obtained good results.

Example 6 In a beaker (A), 500 m of n-butyl alcohol was added.
l, Titanium tetrachloride 10g, 28% ammonia water
150 ml was dropped. Next, in a beaker (B),
Fill with chill alcohol 500ml and strontium 12g
Stir. Do not stir the solution in the beaker (B)
Then, the solution in the beaker (A) is dropped to react.
After that, the reaction solution was replaced with benzene to remove by-products.
I removed it. After refluxing the reaction solution for 2 hours, 4 liters of water was added dropwise.
Hydrolysis was completed. The green-white precipitate obtained is filtered.
After filtering and drying, 13.7 g of fine particle powder was obtained. This powder
As a result of instrumental analysis of powder, SrTiO₃Met. More than
Obtained by the method₃The particle size of the fine particles is 0.01
μm, ultrafine particles are formed without heating
I understand. In the first electrochromic layer,
SrTiO₃Same as Example 1 except using fine particles
An electrochromic device was manufactured by the method described above. Book
The chromochromic device has a transmittance of 15% to 70%.
It takes 40 seconds to change in cyclic voltammogram
From the measurement results, the injected charge amount is 5 mC / cm ²And good
I got good results.

[0030]

EFFECTS OF THE INVENTION Electrodes formed from fine particles of a precipitate obtained by reacting a metal or a metal compound with an organic solvent containing a hydroxy group and then hydrolyzing it, or fine particles formed by heating the precipitate. With the chromic layer, an electrochromic device having high coloring efficiency and capable of easily forming a large-area thin film can be manufactured. Further, since the fine particles of the present invention have a small particle size and good dispersion, it is possible to remove as much as possible raw materials present in particles having a large particle size, impurities mixed during synthesis or purification, and therefore physical properties such as vacuum deposition and sputtering. A uniform thin film having high purity can be obtained even when the thin film is selectively formed. The electrochromic device manufactured by using the material of the present invention can be used for a panel display, a sign board, a light control glass, etc., and therefore has great industrial significance.

Claims (2)

[Claims] 1. An electrochromic device material comprising fine precipitate particles obtained by hydrolyzing a metal alkoxy compound in a medium containing water, or fine particles obtained by heat-treating the fine precipitate particles. 2. An electrochromic device comprising an electrochromic layer containing the electrochromic device material according to claim 1 formed on a transparent electrode substrate.