KR101158425B1 - Electrochromic films using sol-gel coating solutions dispersed of tungsten oxide nano particle and process thereof - Google Patents

Abstract

The present invention provides a crystalline tungsten oxide nanoparticle dispersion type, characterized in that a reducing electrode film can be formed on a transparent electrode in a sol-gel coating solution containing crystalline tungsten oxide nanoparticles having an electrochromic phenomenon. The present invention relates to an electrochromic film using a sol-gel coating solution and a method of manufacturing the same, and is applicable to various fields such as a thermal barrier window film and a flexible display market as well as an outdoor advertising market and a sensor. The device is manufactured in a complex process such as electroplating or sputtering and is manufactured at a high manufacturing cost, which delays commercialization and is thus formed only in a very limited market, whereas the present invention is sputtering or electroplating. There is no need to use expensive equipment such as a roll-to-roll process, It is an advantage that the electrochromic film can be manufactured with a price competitiveness by drastically reducing time.

Description

Electrochromic films using sol-gel coating solutions dispersed of tungsten oxide nanoparticles and process according to crystalline tungsten oxide nanoparticle dispersion type sol gel coating solution

The present invention enables the formation of a reducing electrode film on a transparent electrode at a low temperature in a sol-gel coating solution containing crystalline tungsten oxide nanoparticles having electrochromic phenomena and at the same time a flexible material such as a plastic substrate as well as a glass substrate. In addition, the wet coating can be used to reduce the process cost and to create a flexible device, so that it can be applied to various applications, using the crystalline tungsten oxide nanoparticle dispersion type Sol-Gel coating solution. It relates to an electrochromic film and a method of manufacturing the same.

Electrochromic film is a film whose color changes due to redox reactions at each of the oxidation electrode and the reduction electrode due to the applied potential, and the color is changed. The film is artificially controllable by visible light and infrared ray. Inorganic oxides are used as electrode materials. Representative inorganic oxide electrode materials include FeO, IrO _x , NiO, RhO ₅ , V ₂ O _5, etc., and reduction electrode materials include Bi ₂ O ₃ , CoO, MoO ₃ , Nb ₂ O ₅ , TiO ₂ , WO ₃ and so on.

In general, the components of the electrochromic film are composed of five layers such as a transparent electrode layer, an oxide electrode layer, an electrolyte layer, a reduction electrode layer, and a transparent electrode layer, and in the case of a film form, an adhesive layer and a release film for attaching to a glass or a mirror are included. It is possible to add.

In particular, in recent years there is a tendency to use a lot of glass as a wall material when building construction, and has been increasing continuously. This trend is expected to continue to increase in the future considering the view of natural scenery, the need for natural light, and the functionality of buildings. In particular, in the case of high-rise buildings, the usability of the glass material is increasing in accordance with the demand for lightening the building materials.

Accordingly, a lot of glass materials have been developed to give special functionality to the existing transparent glass, and in particular, the need for energy efficiency improvement is increasing due to the lack of fossil fuel. The most representative ones are heat reflecting glass, heat absorbing glass, low-e glass, and multilayer glass, and the development of films having these functions in general transparent glass is progressing worldwide. However, the aforementioned functional glass and films are fixed glass, and the disadvantage is that the amount of sunlight can not be arbitrarily adjusted by the user after construction. However, in case of electrochromic film, light transmittance can be adjusted according to various demands such as external environmental change, indoor environmental condition, and psychological state of occupants to realize a pleasant indoor environment and increase the energy efficiency of cooling and heating. to be.

The electrochromic film as described above has been developed and patented in various ways, looking at the contents of the patent application, Korean Patent Laid-Open No. 2001-0087586 discloses depositing a conductive indium-tin oxide thin film on the glass film One of two ITO films (1A, 1B) is deposited with MoO ₃ , a reducing color oxide, and another with WO ₃ , which is also a reducing color material, and deposited on top of it. The film is changed from transparent to blue when a polyaniline, which is a conductive polymer, is inserted between two sheets, and a high-frequency compression roller is applied to it, and a glass film having a thickness of 0.05 mm is disclosed in Korean Utility Model Publication No. 0184841 (5A. 5B). ) Indium-tin oxide (4A. 4B) was deposited on the surface, and the reduced color material WO ₃ and the oxidative color development were interposed between the polymer solid electrolyte α-PEO copolymer. Background Art A discoloration film by electric energy is known, which is bonded to both sides of a transition metal oxide film on which IrO ₂ is deposited, by a high frequency roller.

In the case of the above patents, it is possible to form a thin film using tungsten oxide, which is mainly used as a reduction electrode, and conventional development methods are mainly coated with indium-tin oxide (ITO) and fluorine tin oxide (FTO). An oxide electrode and a reduction electrode are prepared on the glass substrate by electroplating, dry coating such as sputtering, or coated on the glass substrate using a sol-gel coating method, followed by high temperature treatment at 250 ° C. or higher. Methods of forming crystalline tungsten oxide on a substrate are mainly used. At this time, when the high temperature treatment is not performed, an amorphous WO ₃ thin film is formed. The amorphous tungsten oxide absorbs visible region when colored but transmits light in the infrared region, so that the thermal barrier property is not good, It is known that there is a problem in durability, while there is a problem that is difficult to use for a plastic substrate during high temperature treatment. In addition, when the thickness of the thin film becomes thicker than 200 nm, the crack of the thin film causes problems in durability of the electrode. Therefore, the thickness of the thin film cannot be thickened. When the thickness of the thin film is formed below 200 nm, it has a low contrast. There was a problem.

Acids such as citric acid or acetic acid (CH ₃ COOH) have been introduced to increase the coating thickness by adding them during the sol-gel process, but this method must also be subjected to a firing temperature of 250 ° C or higher. There is a problem in the use of the substrate, and the electroplating method allows the formation of a thin film by a wet process, but it takes a considerable time to obtain the electrode thin film, it is difficult to coat on a large-area flexible plastic substrate, there is a limitation on the equipment There are disadvantages. In addition, the sputtering method can use both a plastic substrate and a glass substrate, but the expensive equipment by using expensive equipment, there are many disadvantages in the process difficult.

In addition, a method of preparing crystalline tungsten nanoparticles, dispersing it in a solvent such as ethylene glycol, coating a glass substrate, and blowing the solvent through high temperature heat treatment to form an electrode film has been proposed, but this method also requires the use of only a glass substrate. It is proposed to prepare crystalline nanoparticles, and then disperse them using a polymer dispersant or other dispersants together, and then mix them with an organic binder or an inorganic binder such as a polymer, so that they can be used in a low temperature process. And it can be used in the plastic substrate, but there is a problem in the oxidation and reduction rate that influences the electrode discoloration characteristics, there was a disadvantage that the coloring and decolorization rate is slow.

Accordingly, in order to solve the above problems, the present invention provides a sol-gel prepared by dispersing crystalline tungsten oxide nanoparticles having an electrochromic phenomenon in an organic solvent by a mechanical method and mixing with an inorganic binder. The coating solution is to provide an electrochromic film using a crystalline tungsten oxide nanoparticle dispersion type sol-gel (Sol-Gel) coating solution, characterized in that the adhesion between the crystalline tungsten nanoparticles and the substrate is excellent.

In addition, the conventional electrochromic device has a disadvantage in that the synthetic resin substrate can not be used as a heat treatment at a high temperature of more than 250 ℃, the present invention can form a reducing electrode film on a transparent electrode at a low temperature of less than 150 ℃ and at the same time not only glass substrate but also plastic Wet coating can be applied to flexible materials such as materials, which not only reduces the process cost but also makes flexible devices, which can be applied to various applications. Crystalline tungsten oxide nanoparticle dispersion type sol gel (Sol-Gel) Another object is to provide a method for manufacturing an electrochromic film using a coating solution.

In the present invention for achieving the above object in the electrochromic film consisting of a base material, a transparent electrode layer and a reduction electrode layer,

The reduction electrode layer is an electrochromic film, characterized in that the layer formed by coating a tungsten oxide nanoparticle dispersion type sol gel (Sol-Gel) coating solution as a means for solving the problem.

And the present invention is a method of manufacturing an electrochromic film using a transparent electrode layer coating substrate,

The crystalline tungsten oxide nanoparticles are mechanically dispersed using only an organic solvent and an inorganic binder to prepare a coating solution for a reduction electrode (S100);

Forming a reduction electrode layer by wet-coating the prepared coating solution for the reduction electrode on the transparent electrode layer at a low temperature by a sol-gel (Sol-Gel) method (S200);

Method for producing an electrochromic film, characterized in that it comprises another problem solving means.

In the present invention, the sol-gel coating solution is crystalline tungsten oxide nanoparticles 5 to 30% by weight, 60 to 90% by weight of an organic solvent, 5 to 30% by weight of an inorganic binder,

The transparent electrode layer is an electrode layer formed by coating a conductive compound indium tin oxide (ITO) or fluorine tin oxide (FTO) on a substrate,

The substrate is characterized in that the film is produced by selecting one of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyether sulfone (PES) or polycarbonate (PC),

The electrochromic reducing electrode layer is characterized in that the coating thickness is 5 ~ 5,000 nm.

The present invention by means of the above-mentioned solution to the problem is that the expensive electrochromic device currently on the market is heavy and not easy to install because the glass is used as a substrate, and there is a limitation in the application field by using a complex process, while tungsten oxide nanoparticle dispersion It is possible to manufacture electrochromic device at low temperature below 150 ℃ by using Sol-Gel coating solution, which can reduce the process cost and make flexible device, so it can be applied to various applications. Do.

In particular, although the electrode is manufactured by a low temperature process, the crystalline tungsten oxide is contained in the electrode, and thus, a reduced type electrochromic electrode having excellent durability and infrared control function is manufactured in the form of a flexible film, so that the outdoor window market and the flexible display market may not only be used in outdoor markets. It is expected to be able to access various fields such as advertising market and sensors. In addition, the conventional electrochromic device is manufactured in a complicated manufacturing process such as electroplating or sputtering and a high manufacturing cost, and the commercialization is delayed, so that a very expensive market is formed only in a very limited range. Silver does not require expensive equipment such as sputtering or electroplating, and it is possible to apply a roll-to-roll process so that the process time can be drastically reduced, thereby making it possible to manufacture an electrochromic film having a competitive price.

1 is a cross-sectional view of a reduction electrode for an electrochromic film containing crystalline tungsten oxide according to an embodiment of the present invention,
2 is a block diagram of a method of manufacturing a reduction electrode for an electrochromic film containing crystalline tungsten oxide according to another embodiment of the present invention;
3 is a TEM photograph of a reduction electrode coating solution for electrochromic containing crystalline tungsten oxide of Example 1,
4 is an SEM image of a reduction electrode for electrochromic containing crystalline tungsten oxide of Example 1,
5 is a cyclic voltagram curve of an electrochromic reduction electrode containing crystalline tungsten oxide of Example 1,
FIG. 6 relates to an in-situ light transmittance graph of an electrochromic reduction electrode containing crystalline tungsten oxide of Example 1. FIG.

The present invention was devised to solve the above problems, hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings, Figures 1 to 6, in the detailed description of the crystalline tungsten oxide nanoparticle dispersion type sol gel ( Sol-Gel) electrochromic film using a coating solution and a description of the configuration and operation that can be easily known to those skilled in the art of manufacturing a brief or omitted.

Electrochromic film using the crystalline tungsten oxide nanoparticle dispersion type sol-gel (Sol-Gel) coating solution according to the invention is shown in Figure 1,

In the electrochromic film composed of the substrate 10, the transparent electrode layer 20 and the reduction electrode layer 30,

The reduction electrode layer 30 is characterized in that the layer formed by coating the tungsten oxide nanoparticle dispersion type sol-gel (Sol-Gel) coating solution.

Therefore, the electrochromic film having the structure as described above forms the reduction electrode layer 30 on the substrate 10 coated with the transparent electrode layer 20, and when the electricity is applied, the electrode is oxidized and reduced in each layer. Is characterized by a change in color.

The sol-gel coating solution is preferably composed of 5 to 30% by weight of crystalline tungsten oxide nanoparticles, 60 to 90% by weight of an organic solvent, and 5 to 30% by weight of an inorganic binder.

The crystalline tungsten oxide (WO ₃ ) nanoparticles used in the present invention are dispersed directly in an organic solvent and an inorganic binder without using a separate dispersant, thereby preparing a coating solution for a reduction electrode for electrochromic discoloration.

In this case, when the crystalline tungsten oxide nanoparticles are less than 5% by weight, the adhesion to the plastic substrate is excellent when the coating on the cathode, but there is a problem that the color contrast ratio is lowered when the electrochromic color is reduced, exceeding 30% by weight In case of dispersion, not only is it difficult to disperse, but it is also difficult to coat due to reaggregation easily between particles after dispersion. Therefore, the dispersion concentration of the crystalline tungsten oxide is most preferably 5 to 30% by weight.

In addition, various kinds of organic solvents may be used when dispersing the crystalline tungsten oxide nanoparticles, and one or more of alcohols, ethers, ketones, esters, or aromatic hydrocarbons may be selected, and specifically, methanol, Ethanol, propanol, butanol, hexanol, cyclohexanol, diacetone alcohol, ethylene glycol, diethylene glycol, glycerin, diethyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol modobutyl ether, diethylene Glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, acetone, methyl ethyl ketone, acetyl acetone, methyl isobutyl ketone, cyclohexanone, acetoacetic acid ester, methyl acetate, ethyl acetate, acetic acid n- Propyl and i-butyl acetate can be used. One or two or more solvents shown above can be used, and the dispersibility also varies depending on the composition of the solvent.

In the present invention, the amount of the organic solvent is preferably 60 to 90% by weight. When the amount of the organic solvent is less than 60% by weight, the crystalline tungsten oxide nanoparticles may not be dispersed properly, and the amount of the organic solvent is used. When the amount exceeds 90% by weight, the viscosity may be lowered due to excessive use of the organic solvent, so that the coating may not be properly performed when the upper part of the transparent electrode layer 20 is coated.

In addition, the inorganic binder not only functions as a dispersant when dispersing the crystalline tungsten oxide, but also increases adhesion to the substrate, and has excellent electrical conductivity, thereby increasing the discoloration efficiency of the electrochromic film during oxidation and reduction reactions. The amount of is preferably 5 to 30% by weight. When the amount of the inorganic binder is less than 5% by weight, adhesion to the substrate is low, so that the reduction electrode layer may be easily peeled off and there may be a problem in durability. When the amount of the inorganic binder is more than 30% by weight, tungsten is used. Although the adhesion between the oxide and the plastic substrate is excellent, relatively low tungsten oxide concentration results in a low color contrast ratio and a decrease in the porosity of the electrode, which may cause a problem of slowing the speed of electrochromic discoloration.

The inorganic binder usable in the present invention is preferably selected from one or more of silicon oxide, aluminum oxide, titanium oxide, tungsten oxide, manganese oxide, vanadium oxide or cerium oxide.

The nanoparticle size of the crystalline tungsten oxide prepared by the dispersion method as described above has a distribution of about 1 to 200 nm, and when the size of the dispersed crystalline tungsten oxide exceeds 200 nm, a lot of haze is generated in the dispersed solution. In the case of coating using such a coating solution, the optical performance may be a problem even after the electrochromic device is manufactured by maintaining the haze as it is, thus causing a problem in visibility.

The transparent electrode layer 20 is preferably a layer formed by coating an indium tin oxide (ITO) or a fluorine tin oxide (FTO), which is a conductive compound, on a substrate.

And it is preferable that the surface resistance of the transparent electrode layer 20 of the base material used by this invention is 1-200 GPa / sq. It is recommended that the surface resistance of the transparent electrode layer be as low as possible, but not more than 200 mA / sq. In the above case, it is possible to use some of the small area due to the slow electrochromic speed. However, when the large area of 10 cm × 10 cm or more is used, the electrochromic speed is too slow.

The thickness of the transparent electrode layer 20 coated on the substrate used in the present invention is not particularly limited.

In addition, the substrate 10 is preferably a film prepared by selecting one of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfonate (PES) or polycarbonate (PC).

In addition, an electrochromic reducing electrode layer 30 formed by coating a tungsten oxide nanoparticle dispersion type sol gel (Sol-Gel) coating solution on the transparent electrode layer 20 has a coating thickness of 5 to 5,000 nm. . When the coating thickness of the reduction electrode layer is less than 5 nm, the color contrast ratio is low during electrochromic change due to oxidation and reduction, so there is almost no difference in color at the time of coloration and decolorization, so that the discoloration performance is reduced, and the coating thickness of the reduction electrode layer exceeds 5,000 nm. In this case, the thickness of the coating film is so thick that the cracking of the film occurs, and if the coloration or decolorization is performed several times, the reduction electrode coating layer may fall and the durability of the coating film may be lowered.

Therefore, the electrochromic film according to the present invention having the structure as described above has a discoloration transmittance of 70% or more in the visible region when the oxidation voltage is +1.5 to + 3V and the reduction voltage is -0.5 to -2.5V. It is preferable that colored transmittance is 30% or less.

Hereinafter, a method of manufacturing an electrochromic film using a crystalline tungsten oxide nanoparticle-dispersed sol-gel (Sol-Gel) coating solution according to the present invention having a laminate structure as described above will be described in detail with reference to FIG. 2. This is as follows.

The present invention provides a method for producing an electrochromic film using a transparent electrode layer coating substrate,

The crystalline tungsten oxide nanoparticles are mechanically dispersed using only an organic solvent and an inorganic binder to prepare a coating solution for a reduction electrode (S100);

Forming a reduction electrode layer by wet-coating the prepared coating solution for the reduction electrode on the transparent electrode layer at a low temperature by a sol-gel (Sol-Gel) method (S200);

And a control unit.

First, the substrate used in the present invention uses one formed by coating an indium tin oxide (ITO) or a fluorine tin oxide (FTO), which is a conductive compound, on one side thereof.

And in the step of preparing a coating solution for the reduction electrode (S100) crystalline tungsten nanoparticles are ball mill (homogenizer), roll mill (roll mill), ultrasonic disperser (ultra sonicator), bead mill ( It is preferable to grind so that the particle size has a distribution of 1 to 200 nm using a bead mill or a microfliudizer.

The present invention includes the step of mechanically dispersing the tungsten oxide nanoparticles directly into the inorganic binder and the organic solvent without the use of a dispersant in the preparation of the coating solution for the reduction electrode. Various methods are used to disperse the inorganic oxide into nano-sized particles, and it is known that the method using glass beads or ceramic beads is particularly effective. In the case of glass beads, the hardness of the glass beads is weak, so that the glass is broken when dispersed, and thus the glass beads are present as impurities after nano dispersion. Ceramic type beads such as zirconium are commonly used in nano dispersions due to their excellent strength and friction resistance. Using zirconium beads, methods such as horizontal bead mills, vertical bead mills, ball mills and the like can be used. It is known that there is a difference in dispersion degree according to the size and type of zirconium beads. The size of the zirconium beads is not limited in size, but it is theoretically known experimentally that it is possible to be between 0.1 and 10 mm, and that smaller particles can be obtained using smaller beads. Other dispersing devices such as roll mills, ultrasonic dispersers, microfluidizers, homogenizers can also be used, but the dispersibility and dispersion stability are weak compared to bead mills.

The forming of the reduction electrode layer (S200) is a step of forming the reduction electrode layer 30 by a wet-coating method of coating a solution for the reduction electrode on the transparent electrode layer 20 by using a sol-gel (Sol-Gel) method. The reduction electrode layer heat treatment conditions are preferably heat treated for 1 to 30 minutes at 60 ~ 150 ℃.

Thus, the electrochromic film prepared according to the present invention can obtain a thick reduction electrode film by wet coating the coating solution for the reduction electrode on the transparent electrode layer 20 to form a reduction electrode layer 30 in a sol-gel (Sol-Gel) method. Excellent color contrast is reproducible. At the same time, the use of crystalline tungsten oxide nanoparticles has the advantage of ensuring excellent cycle durability and controlling light in the infrared region as well as visible light compared to the amorphous tungsten oxide film. In addition, the present invention can be used for glass substrates and plastic substrates because of the low temperature process, and also enables the roll-to-roll process, and also improves the production speed, thereby reducing energy consumption and reducing the process cost. It can be used to produce a flexible electrochromic film is characterized by.

And the method of coating the reduction electrode layer 30 is spin coating, dip coating, bar coating, spray coating, gravure coating, micro gravure coating, flow coating, capillary coating, slot die coating, knife coating, roll coating or screen It is preferred to coat using a method selected from printing.

The coating solution for the reduction electrode prepared by the above-described method was prepared by bar coating, spray coating, dip coating, spin coating, gravure, micro-gravure and The same coating method can be used. In this case, it is preferable that the temperature of the crystalline tungsten oxide is reduced to 60-150 ° C., and in this case, when the heat-treatment temperature is less than 60 ° C., the curing time of the coating film becomes longer and the curing time becomes longer. Even if the adhesion is secured to some extent, a problem occurs in the durability of the reduction electrode film after the final electrochromic device is formed. In addition, when the heat treatment hardening temperature exceeds 150 ℃, when applied to PET film, the problem that the PET film itself is poor in dimensional safety due to heat occurs, the film is warped, the ITO or FTO transparent electrode is damaged, the electrochromic It may cause a problem of not properly coloring and discoloring. In the case of a film such as polyethylene terephthalate (PEN) or polyether sulfone (PES), its heat resistance is excellent, and thus high temperature treatment is possible, but the film itself is expensive.

The present invention as described above will be described in more detail based on the following examples, but the present invention is not limited by the examples.

1. Preparation of Electrochromic Film

The electrochromic films of Examples 1 to 4 and Comparative Examples 1 and 2 were prepared according to the content ratios described in the following [Table 1].

(Example 1)

30 wt% of crystalline tungsten oxide particles, 65 wt% of ethanol, and 5 wt% of TEOS (Tetraethoxysilane) were mixed in a ball mill, and 300 wt% of 0.3 mm zirconium beads were added thereto, followed by dispersion using a ball mill for 100 hours. To prepare a wetable coating solution. The ITO PET film having a surface resistance of 10 μs / sq. Was coated using a bar coater (NO. 10), and then dried at 120 ° C. for 5 minutes. The size of the specimen was 5cm x 5cm, the thickness of the reduction electrode layer obtained at this time was 260nm. In a liquid electrolyte in which 1 M LiClO ₄ was dissolved in a propylene carbonate (PC) solvent, the characteristics of oxidation, reduction, light transmittance, coloration time, decolorization time, color contrast ratio, and cycle durability of the reduction electrode prepared by the above method were investigated. .

(Example 2)

In Example 1, it was tested in the same manner as in Example 1 except that the TEOS binder content is 10% by weight. The thickness of the reduction electrode layer which is the crystalline tungsten oxide film obtained at this time was 272 nm.

(Example 3)

In Example 1, it was tested in the same manner as in Example 1 except that the TEOS binder content is 20% by weight. The thickness of the reduction electrode layer which is a crystalline tungsten oxide film obtained at this time was 275 nm.

(Example 4)

In Example 1, the test was carried out in the same manner as in Example 1 except that the TEOS binder content was 30% by weight, and an ITO PET film having a surface resistance of 200 mA / sq. Was used. The thickness of the reduction electrode layer which is the crystalline tungsten oxide film obtained at this time was 278 nm.

(Comparative Example 1)

In Example 2, the test was carried out in the same manner as in Example 2 except that the TEOS binder content was 10% by weight and the heat treatment time was performed at 150 ° C. for 60 minutes. The thickness of the reduction electrode layer, which is a crystalline tungsten oxide film obtained at this time, could not be examined for thickness measurement and electrochromic characteristics as the coating film was bent due to deformation of the film by heat and cracking of the coating film occurred.

(Comparative Example 2)

For Example 2, the TEOS binder content was 10% by weight and the surface resistance was 50 ohm / sq. Except for coating with a bar coater (NO. 6) on the phosphorus ITO PET film was tested in the same manner as in Example 2. The thickness of the reduction electrode layer which is the crystalline tungsten oxide film obtained at this time was 220 nm.

division Crystalline tungsten
oxide
(weight%) Ethyl alcohol
(weight%) TEOS Binder
(weight%) Bar coater (NO.) Heat treatment temperature (℃) Heat treatment time (min) Coating thickness
(nm) Example 1 30 65 5 10 120 5 260 Example 2 30 65 10 10 120 5 272 Example 3 30 65 20 10 120 5 275 Example 4 30 65 10 10 120 5 278 Comparative Example 1 30 65 10 10 150 60 - Comparative Example 2 30 65 10 6 120 5 220

2. Evaluation of Electrochromic Film

The electrochromic properties of the crystalline tungsten oxide reduction electrode as a result of evaluating the samples of Examples 1 to 4 and Comparative Examples 1 and 2 prepared by the above method 1 are as shown in Table 2 below.

division Coating thickness
(nm) Coloring transmittance
(%) Bleaching transmittance
(%) Color Response Time (s) Discoloration response
Time (s) Color contrast cycle
durability Example 1 260 8 82 7 14 10.25  〉 10,000 Example 2 272 8 80 7 15 10  〉 10,000 Example 3 275 10 80 11 17 8  〉 10,000 Example 4 278 11 78 13 22 7  〉 10,000 Comparative Example 1 - - - - - - - Comparative Example 2 220 28 68 18 25 2.4  〉 5,000

According to the contents of Table 2, in Examples 1 to 4, the colorless ratio is lower than that of Comparative Example 2, and the decolorization transmittance is high, so that the color contrast ratio is excellent, and the color response time and the color response time are also fast. Electrochromic efficiency and cycle durability were also superior to Example 2.

And in the case of Comparative Example 1, the coating film is bent due to deformation due to heat as the film itself heats at 150 ° C., which is a higher temperature than Examples 1 to 4, for 60 minutes, and the thickness of the coating film is cracked due to cracking of the coating film. Measurement of discoloration characteristics was not possible.

3 is a SEM photograph of a surface of an electrochromic reducing electrode containing crystalline tungsten oxide according to Example 1 of the present invention, and FIG. 4 is a crystal according to Example 1 of the present invention. TEM photograph of a reduction electrode coating solution for electrochromic containing tungsten oxide.

FIG. 5 is a cyclovoltametric graph of the electrochromic reduction electrode containing crystalline tungsten oxide according to Example 1 of the present invention. A platinum counter electrode and Ag / AgNO ₃ reference electrode were used, and the sweep rate was 50mv /. The result of the test with s shows that the shape of the graph follows the CV characteristics of typical tungsten oxide and that a reversible redox reaction occurs. When the potential changes from + 8V to -1.2V, the tungsten oxide electrode is reduced in color to blue, while the electrode becomes oxidized and transparent when the potential changes from -1.2V to + 8V.

6 shows changes in the visible light transmittance when the redox reaction is repeatedly generated using a half cell apparatus including the electrochromic reducing electrode containing the crystalline tungsten oxide according to Example 1 of the present invention as a working electrode. Observed in-situ. Using a platinum counter electrode and Ag / AgNO ₃ reference electrode, repeat the process of coloring for 30 seconds at -1V and for 30 seconds at + 1V by isothermal method, and at 650nm in-situ using UV-Vis spectrophotometer. As a result of measuring the change in transmittance of, the transmittance was 8% for coloring, the transmittance was 82% for discoloring, and the color contrast ratio was 10.25, which is the ratio of the discoloration transmittance to the coloring transmittance, and the response speed was within 15 seconds.

As described above, the electrochromic film using the crystalline tungsten oxide nanoparticle dispersion type Sol-Gel coating solution according to a preferred embodiment of the present invention and a method of manufacturing the same have been described. Those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the present invention.

10: base material layer 20: transparent electrode layer
30: reduction electrode layer

Claims (13)

In the electrochromic film consisting of a substrate, a transparent electrode layer and a reduction electrode layer,
The reduction electrode layer is composed of a layer formed by coating a tungsten oxide nanoparticle dispersion type Sol-Gel coating solution,
The transparent electrode layer is a conductive layer formed by coating indium tin oxide (ITO) or fluorine tin oxide (FTO) on a substrate,
The sol-gel coating solution consists of 5-30% by weight of crystalline tungsten oxide nanoparticles, 60-90% by weight of an organic solvent, and 5-30% by weight of an inorganic binder.
The electrochromic film is a color change transmittance of 70% or more in the visible region when the oxidation, reduction voltage is applied, the electrochromic film, characterized in that less than 30%.
delete delete The method of claim 1,
The substrate is an electrochromic film, characterized in that the film produced by selecting one of the polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyether sulfonate (PES) or polycarbonate (PC).
The method of claim 1,
The electrochromic film is characterized in that the reduction electrode layer having a coating thickness of 5 ~ 5,000 nm.
The method of claim 1,
The organic solvent is an electrochromic film, characterized in that one or more selected from alcohols, ethers, ketones, esters or aromatic hydrocarbons.
The method of claim 1,
The inorganic binder is an electrochromic film, characterized in that one or more selected from silicon oxide, aluminum oxide, titanium oxide, tungsten oxide, manganese oxide, vanadium oxide or cerium oxide.
delete The method of claim 1,
The electrochromic film is an electrochromic film, characterized in that the oxidation voltage is +1.5 ~ + 3V, the reduction voltage is -0.5 ~ -2.5V.
In the manufacturing method of the electrochromic film using a transparent electrode layer coating substrate,
The crystalline tungsten oxide nanoparticles are mechanically dispersed using only an organic solvent and an inorganic binder to prepare a coating solution for a reduction electrode (S100);
Forming a reduction electrode layer by wet coating a coating solution for a reduction electrode prepared above on a transparent electrode layer at a low temperature by a sol-gel (Sol-Gel) method (S200);
Including,
In the preparing of the coating solution for the reduction electrode (S100), the transparent electrode layer is an electrode layer formed by coating indium tin oxide (ITO) or fluorine tin oxide (FTO),
The sol-gel coating solution consists of 5-30% by weight of crystalline tungsten oxide nanoparticles, 60-90% by weight of an organic solvent, and 5-30% by weight of an inorganic binder.
In the step of forming the reduction electrode layer (S300) at the time of low temperature film formation of the reduction electrode layer heat treatment conditions characterized in that the heat treatment for 1 to 30 minutes at 60 ~ 150 ℃.
delete The method of claim 10,
In the preparing of the coating solution for the reduction electrode (S200), the crystalline tungsten nanoparticles may be a ball mill, a homogenizer, a roll mill, an ultra sonicator, or a bead mill. Method of producing an electrochromic film characterized in that the particle size is pulverized to have a distribution of 1 ~ 200nm using a bead mill or a microfliudizer.
delete

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