KR20060088152A - Electrochromic device having complex-type electrochromic layer and method for preparing thereof - Google Patents

Abstract

The present invention relates to an electrochromic device and a method of manufacturing the same. More specifically, the present invention relates to an electrochromic device having an electrochromic layer having a complex structure and having improved electrochromic speed and stability, and a method of manufacturing the same.

Electrochromic, Multi-Coated, Sol-Gel Method, Stability, Electrochromic Speed, Electrochromic Device

Description

Electrochromic device having a electrochromic layer having a composite structure and a method of manufacturing the same. {ELECTROCHROMIC DEVICE HAVING COMPLEX-TYPE ELECTROCHROMIC LAYER AND METHOD FOR PREPARING THEREOF}

1 is a schematic diagram showing the principle of operation of the electrochromic material is coated on the transparent electrode of the glass substrate to transmit or block light. FIG. 1A shows a state in which light is transmitted when the power is cut off, and FIG. 1B shows color change when the power is applied to block only light of a specific wavelength.

Figure 2 is a schematic diagram showing the structure of an electrochromic device according to an embodiment of the present invention.

3 is a scanning electron micrograph of the layer of the electrochromic material of the electrochromic device according to Example 1 of the present invention. Photograph (a) corresponds to part a, b, c + h in FIG. 2, and photograph (b) is an enlarged photograph of part A in photo (a), that is, c + h (electrochromic layer) in FIG. Corresponding.

4 is a result of continuously measuring discoloration and discoloration characteristics when power is repeatedly applied and cut off to the electrochromic device manufactured in Example 1;

Figure 5 shows the results of the characteristics of the electrochromic device prepared in Example 2.

<Description of the code>                 

a, g: substrate

b, f: electrode

c: porous material layer

d: electrolyte

e: electrochromic counter electrode

h: coated electrochromic material

i: sealed gap

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrochromic device and a method of manufacturing the same. The present invention relates to an electrochromic device and a method of manufacturing the same, having an electrochromic layer having a complex structure and improving electrochromic speed and stability.

Electrochromic material generally refers to a material whose color is changed by the flow of electric current when an electric field is applied. A device manufactured using the principle of the electrochromic material is called an electrochromic device (ECD). For example, electrochromic devices are currently used for controlling light transmittance and reflectivity in windows and mirrors.

As an example of the electrochromic device, FIG. 1 schematically shows a smart window in which the electrochromic material (c) is coated on the transparent electrode (b) of the glass substrate (a). As shown in FIG. When it is discolored it blocks light other than light of a certain wavelength.

Electrochromic materials may be divided into organic EC materials, inorganic EC materials, and organic-inorganic hybrid materials.

Representative organic electrochromic materials include polyaniline and the like. In the case of such organic materials, long-term stability is lower than that of inorganic materials, and thus the lifespan is relatively short.

Representative inorganic electrochromic materials include WO ₃ , NiO _x H _y , Nb ₂ O ₅ , V ₂ O ₅ , TiO ₂ , MoO _3, and the like, and the inorganic electrochromic materials generally have a metal oxide form as described above. . The most representative of the inorganic electrochromic materials is WO ₃ , which reacts with ions or electrons in the electrolyte and discolors through the following process.

WO ₃ (bleaching, ^{transparent) + xe - + xM + ⇔} M x WO 3 (coloration, dark blue)

Here, M represents lithium (Lithium), Proton, calcium (Calcium) and the like and typically uses lithium the most. Lithium ions (Lithium Ion) has the same electrochromic effect by reacting with WO ₃ . In order to supply lithium ions, an electrochromic device requires an electrolyte, and a liquid electrolyte and a solid polymer electrolyte, which are used commercially, may be used. Aqueous electrolytes include 1M H ₂ SO ₄ aqueous solution, 1M LiOH aqueous solution, 1M LiClO ₄ aqueous solution, 1M KOH aqueous solution, and the like, and inorganic hydrates include Ta ₂ O ₅ · 3.92H ₂ O, Sb ₂ O ₅ · 4H ₂ O Poly-AMPS, Poly (VAP), Modified PEO / LiCF ₃ SO ₃ and the like are used as the solid polymer electrolyte.

However, the inorganic electrochromic material as described above is excellent in memory effect that the discolored state lasts for a relatively long time, but in general, the electrochromic material is coated on the electrode in a sol state or deposited by a method such as vapor deposition on the electrode in a thin film form. Because of the coating, a non-porous membrane structure is formed, so that the contact with the electrolyte is not smooth, so that discoloration and decolorization rate are slow. In particular, there is a problem in that afterimage discoloration may occur due to a decrease in the discoloration rate, resulting in a decrease in transparency. Therefore, use of an electrochromic device requiring rapid response may be limited.

In order to compensate for the disadvantages of the inorganic electrochromic material and the organic electrochromic material, an organic-inorganic hybrid material may be used as the electrochromic material. The most common organic-inorganic hybrid electrochromic material is an organic material that exhibits electrochromic properties on inorganic particles. A typical type of material is a chemically adsorbed viologen dye on anatase TiO ₂ nanoparticles.

For example, WO97 / 35227 and WO98 / 35267 disclose electrochromic devices using an organic-inorganic hybrid material as an electrochromic material, which is modified by chemically adsorbing an organic electrochromic material such as viologen on titanium oxide. Doing. The electrochromic device having an electrochromic layer made of nanostructured metal oxide whose surface is modified by chemisorption of an organic electrochromic material, which is a kind of organic compound as described above, has a large surface area of the electrode as compared with the conventional electrochromic device, resulting in high driving speed. It is very fast and does not leave afterimages when discoloring. However, the titanium oxide used is preferably in the form of anatase, the anatase type of titanium oxide reacts to UV light, so the light stability is reduced and as a result shorten the life of the device. In addition, the organic electrochromic material used for the surface modification has a problem of poor long-term stability.

That is, in the case of the organic-inorganic hybrid electrochromic material in which the organic electrochromic material is fixed to the nano-metal oxide as described above, the organic electrochromic material is fixed to the inorganic material in the form of a single molecule, which is fixed to the inorganic material. Since the organic material of the monomolecular layer is discolored / discolored by the oxidation / reduction reaction with electrons supplied from the electrode, not the reaction with the ions in the electrolyte, the reaction rate is increased, but a problem occurs in UV stability and long-term reliability.

Meanwhile, methods have been devised to improve the properties of tungsten oxide, an electrochromic material having better light stability than an organic-inorganic hybrid material.

For example, Korean Patent Publication No. 2000-0055936 discloses a specific etching solution by mixing tungsten oxide, which is difficult to etch, and nanomaterial, which is well etched, to form a thin film and etching the nano-sized particles thereon to form a thin film. It is described to fabricate a porous discoloration material layer having a void. Due to the presence of the voids formed in the tungsten oxide electrochromic layer, the reaction surface area was widened, and the movement speed of the ions was increased to improve the discoloration speed and to realize a dark color concentration. However, in order to produce such a porous tungsten oxide requires a uniform etching process, if the etching is not uniform may bring a difference in the color concentration may impair the transmittance of the surface state or reduce the sharpness of the image.

As described above, the conventional electrochromic device has a problem in that the discoloration rate becomes slow because ions in the electrolyte layer mainly move into the electrochromic layer through cracks or voids. In addition, when the pores are not formed uniformly when the pores are artificially formed after the electrochromic layer is formed, there is a problem of uneven coloring.

The present inventors have solved the above-mentioned problems of the conventional electrochromic materials to overcome the shortcomings of the conventional electrochromic materials, has been studied to develop a electrochromic device using a long discoloration speed, excellent light stability and excellent durability.

As a result of such studies, it was found that when nanoparticles capable of forming porous membranes were treated with inorganic electrochromic materials, both the long-term stability of the inorganic electrochromic materials and the improvement of electrochromic speed due to the porous thin film structure were found. The present invention has been completed.

An object of the present invention is to provide an electrochromic device and a method of manufacturing the same that can achieve a fast discoloration speed.

Another object of the present invention is to provide an electrochromic device and a method of manufacturing the same, which can increase the color concentration by maximizing the reaction surface area.

In addition, an object of the present invention is to provide an electrochromic device having a long lifespan with excellent light crystallinity and excellent durability, and a method of manufacturing the same.

The present invention provides an electrochromic device including an electrochromic layer having a porous composite structure formed of a structure in which an inorganic electrochromic material is coated on a nanoparticle forming a porous membrane, and a method of manufacturing the same.

Electrochromic device for achieving the above object of the present invention comprises a first substrate, a second substrate formed to face a predetermined distance apart; First and second electrodes formed on the opposing first and second substrates, respectively; An electrochromic layer formed on the first electrode; And an electrolyte layer filled in a spaced area between the electrochromic layer and the second electrode.

Here, the electrochromic layer has a porous membrane structure including nanoparticles and an inorganic electrochromic material, the nanoparticles are coated by the inorganic electrochromic material, the structure there is a gap between the nanoparticles Has

That is, the electrochromic layer is a composite structure in which an inorganic electrochromic material is coated on the nanoparticles, and the electrochromic layer in the form of a porous membrane is formed by filling the nanoparticles in the form of a membrane to form a plurality of gaps. The present invention also provides an electrode on which the electrochromic layer is formed as described above and a method of manufacturing the electrode.

Hereinafter, the present invention will be described in more detail.

In the present invention, the nanoparticles (hereinafter referred to as "nanoparticles") that can form the porous membrane are solid nanoparticles having a particle size of 1 ~ 1000nm. As such nanoparticles, metal oxides are mainly used. The metal oxide nanoparticles are relatively easy to manufacture by controlling chemical reactions (hydrolysis, condensation or condensation) and molecular combinations such as metal alkoxides or salts, and have excellent adhesion to inorganic electrochromic materials in the form of metal oxides. Excellent coating properties with inorganic electrochromic materials.

Preferably, the nanoparticles capable of forming the porous membrane are WO ₃ , NiO _x H _y , Nb ₂ O ₅ , V ₂ O ₅ , TiO ₂ , MoO ₃ , Al ₂ O ₃ , SiO ₂ , ZrO ₂ , CeO ₂ , ZnO, metal oxides such as Y ₂ O ₃ or mixtures thereof.

When the nanoparticles are coated on the electrode, they have a porous structure because the voids can be formed by the gap created by the filling of the particles. As a result, the contact area with the electrolyte can be widened and the moving speed of the electrolyte can be increased, thereby improving the electrochromic reaction rate of the electrochromic material coated on the nanoparticles.

Nanoparticles to form the porous membrane, preferably has a particle size of 10 ~ 30nm in diameter. When the size of the nanoparticles is too large, the transmittance and light scattering increase the optical properties, and if the particles are too small it is not easy enough to form a porous film because there is not a sufficient gap, such a particle size is preferred Do.

According to the research of the present inventors, sufficient electrochromic properties could not be obtained when the electrochromic material itself was formed of the nanoparticles as described above. For example, coating tungsten oxide sol on the surface of such nanoparticles was superior in terms of discoloration rate than preparing tungsten oxide nanoparticles. This is thought to be because it is easier to discolor only the electrochromic material on the surface of the nanoparticles than to discolor the entire nanoparticles, and the electrochromic speed is fast. In addition, even when a material having electrochromic properties is used as the nanoparticles, it was confirmed that better electrochromic properties and stability can be obtained by recoating an electrochromic material having excellent stability and electrochromic properties.

The porous membrane formed by the nanoparticles may be formed by a known method, for example, a coprecipitation method, a sol-gel method, a gas phase hydrolysis method, a gas evaporation method, a laser ablation method, or the like.

The thickness of the porous membrane is preferably 100nm ~ 5㎛. The thickness of the porous thin film is closely related to the optical properties of the electrochromic device. If the thickness is too thin, it may not have sufficient optical density. If the thickness is too thick, the thickness of the porous thin film may degrade the light transmittance and cause light scattering. There is a problem of becoming a state. Therefore, it is preferable to adjust the thickness as described above.

As the electrochromic material coated on the nanoparticles to form a complex structure, any material having excellent light stability while exhibiting electrochromic properties may be used without limitation. Preferably, it is preferable to use an inorganic electrochromic material having excellent long-term usability than conventional organic electrochromic materials. Non-limiting examples of such inorganic electrochromic materials include WO ₃ , NiO _x H _y , Nb ₂ O ₅ , V ₂ O ₅ , TiO ₂ , MoO ₃ or mixtures thereof.

The electrochromic material is present as coated on the nanoparticles forming the porous membrane. 2 and 3 illustrate a state in which an electrochromic material is coated on nanoparticles forming the porous membrane. Due to the structure as described above, the electrochromic material is thin and wide on the surface of the nanoparticles forming the porous membrane, and thus the electrochromic material has a wide contact area with the electrolyte and enables rapid electrochromic. In addition, when the inorganic electrochromic material having excellent light stability is used, the light stability and long-term use are excellent.

There is no limitation on the method of coating the electrochromic material on the nanoparticles.

For example, first, the nanoparticles may be coated on an electrode, and then, a sol solution may be prepared using an electrochromic material, and then, the nanoparticles may be coated on the nanoparticles coated on the electrode and heat treated to fix the sol solution.

In addition, the nanoparticles and the electrochromic material may be mixed with each other and applied to the electrode in the form of a paste, followed by heat treatment to remove the adhesive from the paste and to fix the nanoparticles and the electrochromic material to the electrode.

Such a sol-gel process is a technique applied to manufacturing ceramics or glass, and according to the present invention, such a sol-gel method may be applied. The sol-gel process dissolves and chemically reacts a metal alkoxide or a salt of a metal as a starting material to a sol state and then undergoes other necessary treatments to ultimately remove incidental organics and remove the oxide-only mesh structure. It is a technique to form. At this time, the precursor is a precursor for obtaining a desired substance, which can be dissolved or chemically reacted to form a sol solution. Further chemical reactions or other necessary treatments result in agglomeration of fine particles or macromolecules, resulting in gelled fluids, such as jelly.

The method of making the sol solution from the electrochromic material is not particularly limited. For example, the precursor of the electrochromic material may be prepared in the form of an acidic or basic sol solution to prepare a sol solution, and then coated on the nanoparticles by dip coating, spray coating, or spin coating.

The sol solution may be prepared, for example, by dissolving the electrochromic material in hydrogen peroxide, or may be prepared using ethanol or another solvent. The solvent used depends on the electrochromic material. If the material that can dissolve the electrochromic material can be used by selecting the appropriate solvent as needed. The solvent is required to make a precursor containing the electrochromic material to be prepared, and those skilled in the art can appropriately select a solvent in consideration of chemical reactions and the possibility of molecular combination. Depending on the solvent choice, the sol solution properties, including the size or phase of the metal oxide produced, can vary.

The concentration of the sol solution and the pH vary depending on the type of nanoparticles used and the type of electrochromic material, and also on which method is applied. Those skilled in the art can easily determine the appropriate concentration and pH as needed.

The coating thickness of the electrochromic material can be appropriately adjusted as necessary, the thickness of about 50 ~ 300nm is the most common. Since the electrochromic material is applied in a sol solution state, it is possible to form a uniform film on the nanoparticles forming the porous film, and may have a state of being attached in the form of particles having a size of several nm.

By coating an inorganic electrochromic material on the nanoparticles as described above, the electrochromic layer becomes more stable. In the case of the conventional organic-inorganic hybrid electrochromic material, a structure in which a coating film is formed by polymerizing an organic material on an inorganic nanoparticle (eg, TiO ₂ ) surface, the organic coating layer itself may be modified by UV, etc. TiO ₂ was also anatase and did not have good stability. However, when coated with an inorganic electrochromic material as in the present invention, since the electrochromic material itself is stable as an inorganic material, it is primarily stable to UV and the like, and the electrochromic material may also serve to protect the nanoparticles therein. This further improves stability.

Tungsten oxide (WO ₃ ) may be used as a representative example of the inorganic electrochromic material. That is, the tungsten oxide may be prepared as a sol solution and used as an electrochromic material. In order to prepare the tungsten oxide sol solution, when the metal tungsten powder is added to hydrogen peroxide (H ₂ O ₂ ) and reacted, hydrogen is generated to produce a tungsten oxide sol solution and hydrogen peroxide is decomposed into water molecules. Using the tungsten oxide sol solution (iso-polytungstate precursor), after coating the tungsten oxide sol solution by spin coating, spray coating or dipping method on the porous membrane by nanoparticles formed on the electrode, By heat treatment between 100 ~ 200 ℃ can be obtained a thin tungsten oxide thin film coated on the porous membrane. The solvent is removed by the heat treatment and the sol solution is agglomerated to form a gel thin film.

In this case, when the heat treatment is performed at a temperature of 200 ° C. or higher, crystallization of the tungsten oxide thin film starts to occur and thus lowers the electrochromic property of the film. Therefore, it is preferable that the heat treatment is performed at the lowest possible temperature so that the tungsten oxide remains in an amorphous state.                     

As another example of the sol solution, the TiO ₂ -CeO ₂ sol solution dissolves Ce (NO ₃ ) ₆ (NH ₄ ) ₂ in an aqueous solution of water and ethanol and Ti [O (CH ₂ ) ₃ CH ₃ ] ₄ and ethanol, CH ₃ COOH is added as catalyst. The color of the solution changes from red to pale yellow over several days by reduction of cerium (IV) by ethanol.

In the electrochromic device, a transparent substrate is preferably used, but a glass substrate is mainly used.

 The first electrode is preferably a transparent electrode. A well-known electrode can be used as said transparent electrode. Non-limiting examples include ITO electrode, FTO electrode and the like.

Meanwhile, the second electrode may be formed as a transparent electrode or a mirror electrode as necessary. For example, the second electrode may be manufactured by coating an electrode material on a glass substrate (second substrate). Depending on the application, transparent materials such as ITO or FTO may be used as electrode materials, metal surfaces may be used, and opaque antimony doped tin oxide (ATO) nano thin films may be used as electrode materials. If necessary, a metal oxide layer may be further formed on the second electrode.

That is, in the case of fabricating an electrochromic device, not a transmissive electrochromic device (transparent when bleaching) but a reflective type (one side has a background color such as white even when bleaching). Because of the additional formation, an opaque electrode may be used instead of a transparent electrode, and an additional counter electrode (eg, ATO, Sb doped SnO ₂ ) may be formed on the transparent electrode.

For example, TiO ₂ and ATO (Sb doped SnO ₂ ) containing 1-10 wt% of NiO _x H _y , TiO ₂ , CeO _2, or CeO ₂ added to the second electrode may be formed by a sol-gel method, sputtering method, screen printing method, or the like. It can be coated so that the thickness is in the range of 0.01 ~ 5㎛.

In order to supply an oxidation / reduction material that reacts with the electrochromic material, an electrochromic device requires an electrolyte. Commercially used liquid electrolytes and solid polymer electrolytes may be used. Solid polymer electrolyte is a material that can transfer ions in the solid state. Unlike liquid electrolyte, there is no problem such as leakage of liquid when manufacturing device, so it is environmentally friendly and thin film can be manufactured in any desired shape. Has the advantage.

Aqueous electrolytes include H ₂ SO ₄ aqueous solution, LiOH aqueous solution, LiClO ₄ aqueous solution, CF ₃ SO ₃ Li aqueous solution, KOH aqueous solution and the like, and inorganic hydrates include Ta ₂ O ₅ · 3.92H ₂ O, Sb ₂ O ₅ 4H ₂ O and the like, and poly-AMPS, Poly (VAP), and Modified PEO / LiCF ₃ SO ₃ are used as the solid polymer electrolyte. Those skilled in the art may select and use various electrolytes in addition to the above-listed electrolytes as necessary.

The present invention also provides a method of manufacturing an electrochromic device comprising a porous electrochromic layer having a structure in which an inorganic electrochromic material is coated on nanoparticles forming a porous membrane.                     

The manufacturing method comprises the steps of first preparing a first, second substrate; Forming first and second electrodes on the first and second substrates, respectively; Forming a porous electrochromic layer coated with an inorganic electrochromic material on nanoparticles forming a porous membrane on the first electrode; And disposing the first and second substrates to face each other at a predetermined distance and filling an electrolyte layer between the porous electrochromic layer and the second electrode.

As a method for forming the porous electrochromic layer, for example, there is a method of forming a porous membrane using nanoparticles on a first electrode and then coating an electrochromic material, or nano to form the porous membrane. A porous electrochromic layer can be formed by applying a paste in which particles and the electrochromic material are mixed to the first electrode.

In the method of manufacturing the electrochromic device, the first substrate on which the electrochromic layer is formed and the second substrate opposite to each other are bonded to each other at regular intervals. At this time, a portion of the adhesive portion is left, through which the electrolyte is injected and sealed using an inert gas in a vacuum chamber. After the electrolyte is injected, a part of the adhesive is completely sealed to maintain airtightness.

The types and characteristics of the first substrate, the first electrode, the electrochromic layer, the second substrate, the second electrode, and the electrolyte are the same as those described above.

2 and 3 show the structure of the electrochromic device having an electrochromic layer formed by the composite coating method of the nano metal oxide as an example of the electrochromic device according to the present invention.                     

First, the electrode b is formed on the glass upper substrate a. In the device, an anatase type having a diameter of about several tens nm is formed on a transparent electrode (b) such as indium tin oxide (ITO) or fluorine doped tin oxide (FTO) as an electrode to form a porous film for forming an electrochromic layer. TiO ₂ or NiO ₂ may be applied in the form of a paste by screen printing or doctor blading to form a thin film. The formed thin film is sintered at 350 to 450 ° C. to remove the binder present in the paste, thereby forming a porous film c having a thickness of 3 to 5 μm. The prepared porous membrane electrochromic material is coated. FIG. 2 illustrates a dip coating using a tungsten oxide sol solution as an electrochromic material.

The opposing electrode of electrochromic material is fabricated on a glass bottom substrate (g) coated with ITO or FTO (f), depending on the application used, either transparent material, metal surface, or opaque antimony doped tin oxide). Herein, the transparent TiO ₂ or TiO ₂ -CeO ₂ sol solution is used to illustrate the thin film (e).

A liquid or solid electrolyte (d) is filled between the lower plate thus prepared and the upper plate coated with tungsten oxide. Subsequently, in the inert atmosphere gas atmosphere containing no moisture, sealing (i) is performed with UV resin to which a ball spacer is added, and then UV curing may be completed to complete the electrochromic device.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. These examples or comparative examples are intended to illustrate the present invention by way of example, but the scope of the present invention is not limited thereto.

<Example 1>

Anatase-type TiO ₂ was coated on a glass substrate coated with fluorine doped tin oxide (FTO) having a width of 15 cm and a length of 15 cm as an electrode, and having a width of 11 cm and a length of 11 cm to form a porous membrane.

Specifically, Ti (O-iPr) ₄ was hydrolyzed to make TiO ₂ nanocrystalline colloidal dispersions. The average particle size of the initially prepared nanocrystals was 7 nm, and autoclave was carried out at 200 ° C. for 12 hours to obtain an average particle size of 12 nm. After distilling the solvent under reduced pressure to make a concentration of 160g / L, 40 wt% of Carbowax 20000 [which is poly (ethylene oxide) having an average molecular weight of 20000] was added to TiO ₂ to give a high viscosity white titania paste. made. This was coated on a glass substrate coated with fluorine doped tin oxide (FTO) by screen printing to form a thin film having a size of 11 cm and 11 cm. The printed thin film was sintered at 400 ° C. to remove the binder and the solvent component included in the paste. After sintering, the thickness was measured by an alpha step, which is a thickness measuring device, and a scanning electron microscope (SEM), and it was confirmed that a porous titanium oxide thin film having a thickness of about 4 μm was formed.

A tungsten oxide sol solution was prepared as follows to coat tungsten oxide as an inorganic electrochromic material on the prepared porous titanium oxide thin film.

In order to produce a tungsten oxide sol solution, tungsten powder (Aldrich Chemical Company, Inc.) having a tungsten content of about 99.95% was mixed with a H ₂ O ₂ solution (a 30% aqueous solution for industry). At this time, tungsten is oxidized to form sol tungsten-oxide. After filtering, impurities are filtered out from the sol-form tungsten-oxide solution, and the remaining H ₂ O ₂ solution is decomposed into hydrogen and water using a platinum catalyst, and then hydrogen is blown to remove tungsten oxide (iso). Tungsten oxide sol solution was prepared.

The tungsten oxide sol solution is coated on the prepared porous membrane (titanium thin film) by a dipping method, and then heat-treated at 150 ° C., and the tungsten oxide thinly coated on nanoparticles (titanium oxide) to form porosity. A thin film was obtained.

ATO was used as a counter electrode (second electrode) of the electrochromic electrode (first electrode). ATO was screen printed on a 11 cm wide and 11 cm long glass substrate, and rutile titanium oxide was screen printed on an ATO thin film for a white background color. As described above, the upper plate and the lower plate on which the electrodes were formed were bonded with a thermosetting adhesive to face each other at an interval of 80 μm, and a portion of the adhesive part was left about 2 mm to inject the electrolyte.

The bonded electrochromic device was injected with γ-butyrolactone with 0.2 M lithium bisimde mixed with argon gas in a vacuum chamber. After the electrolyte injection, the injection portion left for the electrolyte injection was completely sealed by applying an ultraviolet curable adhesive and irradiating ultraviolet rays.

Figure 4 is a continuous measurement of the discoloration and decolorization characteristics of the electrochromic device is manufactured. Power was applied at + 1.5V (discoloration) and -2.5V (discoloration) at 1 minute intervals while changing the polarity of the electrode. As a result, as shown in FIG. 4, discoloration progressed at a high speed up to 20% and then discolored up to 10%. When bleaching, it showed stable reversible characteristics in which the reaction proceeds faster than the discoloration rate. In particular, there was no change in properties even after 100,000 uses.

As described above, the electrochromic device according to the present invention showed stable electrical characteristics even after 100,000 cycles. On the other hand, in the case of the organic-inorganic hybrid device according to Comparative Example 1, degradation of the electrochromic material due to UV occurs gradually, and began to show a pale yellow color without complete decolorization before and after 10,000 times of use.

<Example 2>

An electrochromic device was manufactured in the same manner as in Example 1, except that the iso-polytungstic acid precursor prepared in Example 1 was mixed with a paste of titanium oxide nanoparticles and screen printed. In this method, the characteristics of the tungsten oxide thin film were worse than those of Example 1 due to the heat treatment temperature (400 ° C.) for removing the binder and the solvent of the titanium oxide.

Figure 5 shows the results of discoloration characteristics of the electrochromic device associated with the above results. When the initial voltage was applied, the transmittance was changed to about 35%, and the transmittance at the time of decolorization was not better than that of Example 1, but the behavior of discoloration and decolorization reaction was very similar. According to the present embodiment, there is an advantage in that the reaction speed of discoloration / discoloration is good and the manufacturing process is simple.

<Example 3>

An electrochromic device was manufactured in the same manner as in Example 1, except that the porous membrane was formed using the tungsten oxide nanoparticles prepared below instead of the titanium oxide nanoparticles.

Nano-size tungsten oxide was fabricated by laser ablation method (Lambda Physik, model: LPX300, KrF) using a tungsten target. The purity of the tungsten target was 99.99% and the reaction chamber was filled with oxygen at a pressure of about 800 torr to form tungsten oxide. The tungsten oxide nanoparticles thus prepared had a size of 10-20 nm and was white. As a result of analyzing the prepared nanoparticles by X-ray diffraction pattern (XRD), it was confirmed as monoclinic nano grains.

It was coated with tungsten oxide as in Example 1 as an electrochromic material. The coated electrochromic layer is in a form in which nano-tungsten oxide is thinly coated with an amorphous oxide thin film. The tungsten oxide prepared by the sol gel process is amorphous and has excellent discoloration / discoloration rate as compared to crystalline (monocrystalline) tungsten oxide produced by laser ablation.

A 10 x 10 cm ² smart window sample was fabricated in this way and measured for discoloration and decolorization rates. It took about 20 seconds when the transmittance changed from 70% to 10% and about 180 seconds when changing from 10% to 70%. . Discoloration takes a relatively long time, but the memory characteristics that the discolored state persists without applying power is very good, and the transmittance of the discolored state hardly changed even after one week.

Comparative Example 1

Example 1 except that the modified nanostructured metal oxide film was chemically adsorbed on titanium oxide according to the method described in WO 98/35267 as an electrochromic layer (if using an organic-inorganic hybrid electrochromic layer). An electrochromic device was manufactured in the same manner.

In the case of the organic-inorganic hybrid device according to the comparative example, degradation of the electrochromic material due to UV gradually occurred, and after about 10,000 times of use, the color of the organic-inorganic hybrid device did not completely discolor and began to show a pale yellow color.

In the case of the electrochromic device according to the present invention, long-term stability and fast discoloration rate can be obtained by forming the electrochromic layer into a composite structure. As a result, the range of use can be extended to energy-saving smart windows in buildings that must be used stably for at least 10 to 20 years, as well as advertisements and outdoor purifier displays that require UV stability.

Claims (15)

First and second substrates disposed to face each other; First and second electrodes respectively formed on the first and second glass substrates facing each other; An electrochromic layer formed on the first electrode; And And an electrolyte layer filled in the spaced area between the porous electrochromic layer and the second electrode. The electrochromic layer has a porous membrane structure including nanoparticles and inorganic electrochromic material, the nanoparticles are coated by the inorganic electrochromic material, characterized in that there is a gap between the nanoparticles. Electrochromic device. The electrochromic device according to claim 1, wherein the nanoparticles have a particle diameter of 10 to 30 nm. The electrochromic device according to claim 1, wherein the nanoparticles are nanoparticles made of a metal oxide. The method of claim 3, wherein the metal oxide is WO ₃ , NiO _x H _y , Nb ₂ O ₅ , V ₂ O ₅ , TiO ₂ , MoO ₃ , Al ₂ O ₃ , SiO ₂ , ZrO ₂ , CeO ₂ , ZnO and Electrochromic device, characterized in that at least one selected from the group consisting of Y ₂ O ₃ . The electrochromic device according to claim 1, wherein the porous membrane has a thickness of 100 nm to 500 µm. The electrochromic device of claim 1, wherein the inorganic electrochromic material is at least one selected from the group consisting of WO ₃ , NiO _x H _y , Nb ₂ O ₅ , V ₂ O ₅ , TiO _2, and MoO ₃ . . Preparing a first and a second substrate; Forming first and second electrodes on the first and second substrates, respectively; Forming a porous electrochromic layer coated with an inorganic electrochromic material on nanoparticles forming a porous membrane on the first electrode; And Disposing the first and second substrates to face each other at a predetermined distance and filling an electrolyte layer between the porous electrochromic layer and the second electrode; Method of manufacturing an electrochromic device comprising a. The method of claim 7, wherein the forming of the electrochromic layer comprises: forming a porous film on the first electrode using the nanoparticles; And coating an electrochromic material on the porous membrane. The method of claim 8, wherein the porous membrane is formed by coprecipitation, sol-gel, gas phase hydrolysis, gas evaporation, or laser ablation. The method of claim 8, wherein the electrochromic material is coated on the porous membrane by dip coating, spray coating or spin coating. The method of claim 8, wherein the coating of the electrochromic material on the porous membrane, Preparing a sol solution comprising an electrochromic material; Applying said sol solution to a porous membrane; And Heat-treating the porous membrane to which the sol solution is applied; Method comprising a. 8. The method of claim 7, wherein forming the electrochromic layer comprises mixing nanoparticles and the electrochromic material to form the porous membrane and applying the mixture to a first electrode. Way. An electrochromic device manufactured by the method of any one of claims 7 to 12. An electrode having an electrochromic layer formed on its surface, The electrochromic layer has a porous membrane structure including nanoparticles and inorganic electrochromic material, The nanoparticles are coated by the inorganic electrochromic material, An electrode, characterized in that there is a gap between the nanoparticles. (1) forming a porous thin film using nanoparticles on an electrode; (2) preparing a sol solution comprising an electrochromic material; (3) applying the sol solution to the porous thin film formed in (1); And (4) heat-treating the porous thin film to which the sol solution is applied; Method for producing an electrode according to claim 14 comprising a.

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