KR20090029982A - Method for preparing electrochromic polymer nanotube and electrochromic device utilizing the same - Google Patents

Abstract

A method for preparing an electrochromic polymer nanotube and an electrochromic device using the same are provided to synthesize a nonotube in RTILs(Room Temperature Ionic Liquids) by using a porous template and surface-process the synthesize nanotube by using surfactant, thereby drastically increasing a surface size per unit volume of an electrochromic polymer material. A nanotube is surface-processed by using surfactant to improve a response speed of electrochromic reaction and make electrolyte to fully contact a nanotube air bubble. A porous template is an anodized aluminum oxide membrane. A transparent electrode is made according to a normal ITO transparent electrode depositing method by putting the anodized aluminum oxide membrane in a sputtering chamber. The first transparent electrode is made by separating an AAO/PEDOT/ITO surface-process by surfactant in an electro polymerizing apparatus and attaching the AAO/PEDOT/ITO on an ITO glass substrate. Another ITO glass substrate is the second transparent electrode. 0.2M LiClO/GBL(gamma-butyrolactone) is injected between the first and second transparent electrodes. The injected portion is sealed by epoxy, thereby producing an electrochromic device.

Description

Method for preparing electrochromic polymer nanotube and electrochromic device using same {Method For Preparing Electrochromic Polymer Nanotube and Electrochromic Device Utilizing The Same}

The present invention relates to a method for manufacturing an electrochromic polymer nanotube and an electrochromic device using the same. More particularly, in the preparation of an electrochromic polymer nanotube, a room temperature ionic liquid (RTILs) is used by using a porous template. Electropolymerizing the electrochromic polymer nanotubes in the inside), and the electrochromic polymer nanotubes synthesized by the above method using a surface active agent, the electrochromic polymer having a fast reaction speed and excellent contrast It relates to a method for manufacturing a nanotube and an electrochromic device using the same.

Electrochromism is a phenomenon in which a color is reversibly changed due to an electric field when a voltage is applied.A material in which the optical properties of the material can be reversibly changed by an electrochemical redox reaction is called an electrochromic material. do. That is, the electrochromic material does not have a color when the electric field is not applied from the outside and becomes colored when the electric field is applied, or is colored when the electric field is not applied from the outside. This has the property of disappearing.

Such electrochromic materials include inorganic metal oxides such as tungsten oxide and molybdenum oxide, and electrochromic polymers such as polypyrrole, polyaniline, polyazulene, polythiophene, polypyridine, polyindole, and polyquinone, and include viologen and anthraquinone. And organic discoloring materials such as phenocyazine. In particular, the electrochromic polymer material has recently been actively studied due to the characteristics of the organic material, that is, the variety of synthetic methods, the ease of forming into a fiber or film form, flexibility, electrochromic, low production cost.

As such, the electrochromic device using the electrochromic polymer material has excellent reflectivity, excellent flexibility, portability, and light weight without the need of an external light source, and thus, it is expected to be widely used in various flat panel displays. In particular, recently, as an electronic medium replacing paper, it has a high possibility of being applied to an electronic paper (E-paper), which is being actively researched.

However, in order for an electrochromic device using an electrochromic polymer material to realize display performance as paper, it is necessary to make the electrochromic response speed of the electrochromic polymer material faster and to improve the contrast when discoloring and decolorizing. It is becoming.

The present invention is to overcome the problems of the prior art as described above, one object of the present invention is to provide a method for producing an electrochromic polymer nanotubes with a fast electrochromic response speed and excellent contrast when discoloring and discoloring.

Another object of the present invention is to provide an electrochromic device having a fast electrochromic response speed and an excellent contrast when discoloring and discoloring.

One aspect of the present invention for achieving the above object is, in the preparation of the electrochromic polymer nanotubes, the step of electropolymerizing the electrochromic polymer nanotubes in the pores of the porous template using a room temperature ionic liquid as the electrolyte And surface treating the electrochromic polymer nanotubes synthesized by the method using a surfactant.

Another aspect of the present invention for achieving the above object, in the electrochromic device comprising a first transparent electrode, a second transparent electrode, an electrochromic material layer and an electrolyte, wherein the electrochromic material layer in the method of the present invention Electrochromic device comprising an electrochromic polymer nanotubes.

In the method for producing an electrochromic polymer nanotube according to the present invention, a nanotube is synthesized in a room temperature ionic liquid using a porous template, and the electrochromic polymer nanotube is subjected to a surface treatment using a surfactant, thereby electrochroming. The surface area per unit volume of the polymer material is significantly increased, and the surface of the hydrophobic electrochromic polymer nanotube is changed to hydrophilicity.

Therefore, the electrochromic device including the electrochromic polymer nanotube manufactured by the method of the present invention has a large area of the electrochromic active layer adjacent to the electrolyte and good wettability and contact state between the electrolyte and the electrochromic active layer. It shows very fast electrochromic phenomenon and shows excellent contrast when discoloring and discoloring the device.

Hereinafter, with reference to the drawings will be described in more detail the manufacturing method of the present invention.

1 is a conceptual diagram illustrating a manufacturing method of the present invention. As shown in FIG. 1, the method for preparing an electrochromic polymer nanotube according to the present invention comprises the steps of synthesizing an electrochromic polymer nanotube in the pores of a porous template by electropolymerization using a room temperature ionic liquid as an electrolyte and It characterized in that it comprises the step of surface treatment of the synthesized nanotubes using a surfactant.

Referring to the manufacturing method of the present invention in more detail step by step as follows.

 (Iii) electropolymerizing electrochromic polymer nanotubes using room temperature ionic liquids as electrolytes

First, a porous template is placed in a sputtering chamber, and a transparent electrode is formed on the rear surface of the porous template according to a general ITO transparent electrode deposition method, and then a general electrochemical reaction cell is formed using this as a working electrode.

The counter electrode and the reference electrode are installed in the cell, the electrolyte solution in which the precursor of the electrochromic polymer material to be polymerized is filled, and electropolymerization is performed under a constant current according to a conventional method. At this time, if the polymerization rate is properly adjusted, the electrochromic polymer material to be polymerized will grow along the walls inside the pores of the porous template.

The preparation method according to the present invention is characterized in that the room temperature ionic liquid is used as the electrolyte in synthesizing the electrochromic polymer nanotubes by the electropolymerization method.

An ionic liquid is an ionic salt having a property of being present as a liquid at a temperature of 100 ° C. or lower. In particular, an ionic liquid present as a liquid at room temperature is referred to as room temperature ionic liquids (RTILs).

Since ionic liquids are nonvolatile, they have no vapor pressure and have high ionic conductivity. In particular, since the polarity is large, it dissolves inorganic and organometallic compounds well, and has a unique characteristic of being present as a liquid in a wide temperature range, and thus it can be applied to a wide range of chemical fields such as catalyst, separation, and electrochemistry. In addition, ionic liquids are non-toxic, non-flammable, have excellent thermal stability, and are environmentally friendly next-generation solvents that can replace existing toxic organic solvents such as wide temperature range, high solvation ability, and non-coordinating ability as liquids. It has physical and chemical properties as

In the production method of the present invention, particularly by using an ionic liquid at room temperature as an electrolyte for electropolymerization, high quality electrochromic polymer nanotubes having a uniform aspect ratio at room temperature can be synthesized. When using a general organic solvent, it is affected by the purity and structure of the electrical polymer due to decomposition of organic compounds during electropolymerization, generation of harmful radicals by moisture, oxygen, etc. It seems to be because it is hardly affected by by-products and impurities during the electrical polymerization. Prior to the start of the electropolymerization, it is advantageous to form an electrochromic polymer having a more uniform nanotube structure after removing the impurities such as moisture and oxygen in the room temperature ionic liquid in a vacuum atmosphere.

2 and 3 are scanning electron microscope (SEM) photographs of electrochromic polymer nanotubes synthesized by the above method. As shown in Figures 2 and 3, the electrochromic polymer prepared by the method of the present invention is very thin and elongated tube aspect ratio (aspect ratio) is more than 100, the surface area is greatly increased.

Therefore, when the nanotubes prepared by the method of the present invention are used as the electrochromic material layer of the electrochromic device, the contact area between the active layer and the electrolyte is increased to shorten the diffusion distance of ions in the electrolyte during the electrochromic reaction. This speeds up the response of the electrochromic device.

Specific examples of room temperature ionic liquids used as electrolytes for electropolymerization in the process of the present invention are 1-alkyl-3-methyl imidazolium hexaflurophosphate ([BMIM] [PF ₆ ]), wherein the double alkyl group has 4 carbon atoms. Is used a compound that exhibits room temperature ionic character between 8 and 8. In addition, as the 1-alkyl-3-methyl imidazolium boron tetrafluoride compound, a compound in which a double alkyl group exhibits room temperature ionic character between 2 and 12 is used. However, the room temperature ionic liquid compound of the present invention is not necessarily limited thereto.

In addition, specific examples of the electrochromic polymer used in the method of the present invention include, but are not limited to, polypyrrole, polyaniline, polythiophene, polypyridine, polyindole, polycarbazole, polyazine, polyquinone or polymers thereof. In particular, PXDOT such as poly (3,4-ethylenedioxythiophene) (PEDOT), poly (3,4-propylenedioxythiophene) (PProDOT) or derivatives thereof is preferably used. PXDOTs can be applied to a variety of electrical or optoelectronic devices, including LEDs, transistors, rechargeable batteries, sensors, and electrochromic devices due to their unique conduction properties, excellent thermal and environmental stability, high oxidation and reversibility.

Materials of the porous template that can be used in the method of the present invention include a metal oxide anode membrane such as aluminum oxide anode membrane (AAO), a titania anode membrane, or a porous membrane of a polymer including polypropylene, nylon, polyester or block copolymer. A film or the like may be used, but preferably, an aluminum oxide anode film is used. In this case, the porosity of the porous material having a diameter of 10 to 300 nm is preferably 3 to 50% based on the cross-sectional area.

At this time, the electrochromic polymer nanotubes prepared by the method of the present invention preferably have an outer diameter of 30 to 300 nm, a tube thickness of 5 to 100 nm, and a length of 0.1 to 10 μm.

(Ii) electrochromic polymer nanotubes using a surfactant; Surface treatment  step

4 is a schematic diagram showing the dimensions of the electrochromic polymer nanotubes synthesized by the above method. As shown in FIG. 4, the electrochromic polymer nanotubes synthesized by electropolymerization as described above are very thin and long in shape, and in particular, the surface of the nanotubes exhibits strong hydrophobic surface characteristics. Therefore, when the electrochromic device is manufactured using such nanotubes, the electrolyte is difficult to invade into the pores of the nanotubes, and in particular, wetting between the hydrophilic electrolyte and the hydrophobic nanotube surface becomes poor. In addition, void spaces are formed in the pores of the nanotubes, resulting in poor contact between the electrochromic active layer and the electrolyte.

In addition, the interface energy difference between the hydrophobic nanotubes and the hydrophilic electrolyte prevents the formation of counter ions during electrochromic processes by oxidation and reduction reactions, resulting in a delay in response speed.

Accordingly, the method of the present invention includes the step of surface-treating the nanotubes with a surfactant to ensure that the electrolyte is in sufficient contact within the nanotube pores and to improve the response speed of the electrochromic reaction. It features. 5 is a schematic view for explaining the effect of the surface treatment of nanotubes with a surfactant.

That is, when the nanotubes are surface treated using a gaseous surfactant, the surfactants may form a thin surfactant layer in the pores of the nanotubes as shown in FIG. 5 through a self-assembly process. To form.

At this time, when the power is applied to the electrode containing the PXDOT / surfactant, the inner wall of the pore of the PXDOT nanotubes is more hydrophilic, and the contact between the inner wall of the nanotube pore and the electrolyte is significantly increased. It will facilitate the entry into the tube. On the other hand, when the applied power source is removed, the double layered charge complex is kept longer than the untreated PXDOT nanotube, which means that it has a longer bistability. In the production of electrochromic polymer devices using highly polar electrolyte solvents, the problems caused by insufficient polarity of the electrochromic polymer due to insufficient polarity of the electrolyte, such as response speed, contrast reduction, and double safety The problem can be solved by treatment of the surfactant.

Specific examples of the surfactant used in the method of the present invention include (HOO ₂ CR-Si (OCH ₃ ) ₃ ) (carboxy modified alkyl trimethoxy silane), (HOO ₂ SR-Si (OCH ₃ ) ₃ ) (sulfuric acid modified silane compounds such as alkyl trimethoxy silane) and (H ₂ NR-Si (OCH ₃ ) ₃ ) (amino modified alkyl trimethoxy silane) are used. In this case, an alkyl group compound having 1 to 30 carbon atoms may be used. However, the present invention is not limited thereto.

According to another aspect of the present invention, an electrochromic polymer nanotube prepared by the method and a first transparent electrode are used as a first surface, and a second transparent electrode is used as a second surface between the first and second surfaces. It provides an electrochromic device comprising an electrolyte.

6 is a schematic cross-sectional view of an electrochromic device according to one embodiment of the present invention. Referring to FIG. 6, the electrochromic device of the present invention includes a first transparent electrode 10, an electrochromic polymer nanotube layer 20, an electrolyte layer 30, and a second transparent electrode 40. At this time, the thickness of the electrochromic polymer nanotube layer 20 (the length of the nanotubes) is preferably 0.1 ~ 10 ㎛.

As the transparent electrodes 10 and 40 of the present invention, a normal transparent electrode may be used without limitation, but it is preferable to use an ITO transparent electrode.

Examples of the electrolyte used in the electrolyte layer 30 in the present invention may be a liquid type, a molten salt type, a solid type, and consists of an electrolyte containing one or more inert salts electrochemically. Specifically, for example, propylene carbonate, ethylene carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, butylene carbonate, benzonitrile, acetonitrile, tetrahydrofuran, 2-methyltetrahydrofuran, gamma-butyrolactone, Dioxolane, 4-methyldioxolane, N, N-dimethylformamide, dimethylacetamide, dimethylsulfoxide, dioxane, 1,2-dimethoxyethane, sulfolane, dichloroethane, chlorobenzene, nitrobenzene, Solvents such as dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, methyl propyl carbonate, methyl isopropyl carbonate, ethyl propyl carbonate, dipropyl carbonate, dibutyl carbonate, diethylene glycol or dimethyl ether, such as tri-alkyl-imidazolium Dazolium-based molten salt or a mixture of these materials in LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiAsF ₆ , LiClO ₄ , LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, LiC ₄ F ₉ SO ₃ , LiSbF ₆ , LiAlO ₄ , LiAlCl ₄ , LiN (C _x F _{2x +1} SO ₂ ) (C _y F _{2y +1} SO ₂ ) (Wherein x and y are natural water), one of an electrolyte composed of lithium salts such as LiCl, LiI, or a mixture of two or more thereof can be used by dissolving them. Inert salts such as lithium salts may be present in the electrolyte at a concentration of preferably 0.01 to 1.0 M, more preferably 0.05 to 0.2 M. In addition, a ferrocene-based compound and a phenoxyazine-based compound may be present in the electrolyte at a concentration of 0.01-0.2 M as the redox material.

In the manufactured electrochromic device, the porous substrate of the electrochromic polymer nanotube layer 20 is electrically connected to the first transparent electrode 10 by energizing the first transparent electrode 10 and the second transparent electrode 40. The activity occurs in the electrochromic polymer nanotubes, which are electrochromic materials present in the interior, and become discolored.

In the electrochromic device according to the present invention, since the electrochromic polymer of the electrochromic polymer nanotube layer 20 is in the form of a very thin and long tube treated with a surfactant, the surface area is greatly increased, so that the area of the active layer adjacent to the electrolyte is increased and the The thickness is also very thin, resulting in very fast electrochromic phenomena and excellent contrast.

[ Example ]

The present invention will be described in more detail with reference to the following examples, but these examples are for illustrative purposes only and should not be construed as limiting the protection scope of the present invention.

Electropolymerization of Electrochromic Polymer Nanotubes

Whatman aluminum oxide anode film (AAO, Anodisc 13,200nm) was used as the porous template. The aluminum oxide anode film was placed in a sputtering chamber to form a transparent electrode on the back side according to a general ITO transparent electrode deposition method.

Subsequently, electropolymerization was carried out by a conventional three-electrode system. The deposited AAO / ITO is fixed to an electrochemical cell to function as a working electrode. At this time, the front side of the AAO / ITO is exposed to the electrolyte about 1 cm 2, and a copper sheet is placed on the back side (ITO side). Attach and apply a positive electrode. As a counter electrode, a platinum sheet made of platinum wire was used, and a standard Ag / AgCl electrode was used as a reference electrode. An electrochemical station (CH Instrument, 660C) connected to a computer was used to control the electrochemical process.

As an electrolyte for electropolymerization, [BMIM] [PF ₆ ] (1-butyl-3-methyl imidazolium hexaflurophosphate), a room temperature ionic liquid containing 0.3 mol / L of EDOT monomer, was used.

The porous AAO template was immersed in the electrolyte for about 2 hours to allow the electrolyte to sufficiently diffuse into the pores, and then subjected to electropolymerization for 40 minutes at a 1.5 V fixed potential.

The average outer diameter of the polymerized nanotubes is about 200 nm, which is related to the pore size of the AAO template. The average inner diameter of the nanotubes is about 120 nm and the average length is about 3 μm.

Subsequently, the porous AAO / PEDOT in which the ITO layer was formed was heated to 100 ° C. under a vacuum atmosphere of 0.2 atm or lower, and then surface treated using HOOC (CH ₂ ) ₈ Si (OCH ₃ ) ₃ in a gaseous state.

Fabrication of Electrochromic Device

The AAO / PEDOT / ITO surface-treated with a surfactant as described above is separated from the electropolymerization apparatus and attached to the ITO glass substrate as the first transparent electrode, and another ITO glass substrate as the second transparent electrode on the opposite side. 0.2 M LiClO / GBL (γ-butyrolactone) was injected into the electrolyte and sealed with epoxy to prepare an electrochromic device.

When the first transparent electrode of the finished device is a cathode and the second transparent electrode is applied as an anode, a voltage of 1 to 1.5 V is applied, and the electrochromic material is activated, and the color becomes dark blue purple upon reduction. On the contrary, when the voltage is reversed and oxidized, the electrochromic material loses its activity and becomes discolored and becomes transparent. If no electricity is applied after the oxidation / reduction reaction, the color of the oxidation / reduction state is maintained for at least 1 hour. At this time, the response speed at the time of discoloration and discoloration was very fast under 500 ms, and the contrast was excellent because there was no afterimage remaining at the time of discoloration.

Although the present invention has been described in detail above, these are merely for the purpose of explanation, and the present invention is capable of many modifications by those skilled in the art to which the present invention pertains within the scope of the technical idea of the present invention. Will be self explanatory.

1 is a conceptual diagram illustrating a method of manufacturing an electrochromic polymer nanotube according to an embodiment of the present invention,

2 is a planar scanning electron microscope (SEM) photograph of an electrochromic polymer nanotube layer prepared by the method of the present invention;

Figure 3 is a scanning electron microscope (SEM) photograph of the electrochromic polymer nanotube layer prepared by the method of the present invention,

4 is a perspective view of an electrochromic polymer nanotube produced by the method of the present invention,

Figure 5 is a schematic diagram for explaining the effect of the surface treatment of nanotubes with a surfactant in the production method of the present invention,

6 is a schematic cross-sectional view of an electrochromic device according to an embodiment of the present invention.

* Description of the symbols for the main parts of the drawings *

10: first transparent electrode 20: electrochromic polymer nanotube layer

30 electrolyte layer 40 second transparent electrode

Claims (11)

In preparing electrochromic polymer nanotubes using a porous template, Electropolymerizing the electrochromic polymer nanotubes in the pores of the porous template using a room temperature ionic liquid in which a precursor of the electrochromic polymer material is dissolved as an electrolyte; And Method for producing an electrochromic polymer nanotubes comprising the step of surface-treated the synthesized electrochromic polymer nanotubes using a surfactant. The electrochromic polymer nanotube of claim 1, wherein the electrochromic polymer material is selected from the group consisting of polypyrrole, polyaniline, polythiophene, polypyridine, polyindole, polycarbazole, polyazine and polyquinone. Manufacturing method. The method of claim 1, wherein the electrochromic polymer material is PEDOT, PProDOT, or a derivative thereof, PXDOT. The method of claim 1, wherein the porous template is an aluminum oxide anode film. The method of claim 4, wherein the porous template has a pore diameter of 10 to 300 nm and a pore density of 3 to 50% based on the cross-sectional area. The method of claim 1, wherein the room temperature ionic liquid is 1-alkyl-3-methyl imidazolium hexafluro phosphate ([BMIM] [PF ₆ ]) or 1-alkyl-3-methyl imidazolium boron tetrapulo Method for producing an electrochromic polymer nanotubes, characterized in that the lide compound. The method of claim 1, wherein the surfactant is (HOO ₂ CR-Si (OCH ₃ ) ₃ ) (carboxy modified alkyl trimethoxy silane), (HOO ₂ SR-Si (OCH ₃ ) ₃ ) (sulfuric acid modified alkyl trimethoxy silane) And (H ₂ NR-Si (OCH ₃ ) ₃ ) (amino modified alkyl trimethoxy silane). The method of manufacturing an electrochromic polymer nanotube, characterized in that it is selected from the group consisting of silane compounds. The method of claim 1, wherein the surface treatment with the surfactant is performed in a state in which the surfactant is in a gaseous phase. The method of claim 1, wherein the nanotubes have an outer diameter of 100 to 300 nm, a thickness of 5 to 100 nm, and a length of 0.1 to 10 μm. In the electrochromic device comprising a first transparent electrode, a second transparent electrode, an electrochromic material layer and an electrolyte, Electrochromic device, characterized in that the electrochromic material layer comprises an electrochromic polymer nanotube prepared by the method of claim 1 to claim 9. The electrochromic device according to claim 10, wherein the thickness of the electrochromic material layer is 0.1 to 10 μm, the length of the nanotubes.

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