JP2015146227A - Method of producing conductive coating, conductive coating, conductive film and electrode for dye-sensitized solar cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of producing a conductive coating with excellent conductivity and coating strength, the conductive coating, a conductive film comprising the conductive coating, and an electrode for dye-sensitized solar cell comprising the conductive coating or the conductive film.SOLUTION: A method of producing a conductive coating comprises a step of preparing a dispersion liquid in which an amount of desorption of carbon monoxide is 1000-10000 μmol/g and an amount of desorption of carbon dioxide is 500-5000 μmol/g at 150-950°C in temperature-programmed desorption method, a step of forming a coating from the dispersion liquid, and a step of bringing the coating into contact with a reductant for reduction.

Description

  The present invention relates to a method for producing a conductive film, a conductive film, a conductive film, and an electrode for a dye-sensitized solar cell.

  In recent years, carbon-based materials have been widely used as constituent materials for conductive layers and catalyst layers of electrodes used in electronic devices and electronic members such as touch panels, solar cells, and fuel cells. For example, Patent Document 1 proposes a fluorinated multilayer carbon nanomaterial as a material useful for electrochemical devices such as primary batteries and secondary batteries, particularly lithium batteries.

Special table 2009-515813

  However, the carbon nanotube described in Patent Document 1 has poor dispersibility, and the volume resistivity of a film formed using the carbon nanotube has not been sufficiently low.

  The objective of this invention is the manufacturing method of the electrically conductive film excellent in electroconductivity and film | membrane strength, the said electrically conductive film, the electrically conductive film provided with the said electrically conductive film, and the dye-sensitized sun provided with the said electrically conductive film or the said electrically conductive film. The object is to provide an electrode for a battery.

  As a result of intensive studies aimed at solving the above problems, the present inventors have found that the desorption amount of carbon monoxide and the desorption amount of carbon dioxide at 150 to 950 ° C. in the temperature programmed desorption method are within a predetermined range. The present inventors have found that the above-mentioned problems can be solved by forming a dispersion containing the carbon nanotubes in the film, and reducing the film in the state of the film, thereby completing the present invention.

That is, the present invention
[1] including carbon nanotubes having a carbon monoxide desorption amount of 1000 to 10,000 μmol / g and a carbon dioxide desorption amount of 500 to 5000 μmol / g at 150 to 950 ° C. in the temperature programmed desorption method. A method for producing a conductive film, comprising: a step of preparing a dispersion; a step of forming a film from the dispersion; and a step of bringing the film into contact with a reducing agent and reducing the film.
[2] A conductive film produced by the production method according to [1],
[3] A conductive film comprising the conductive film according to [2] on a substrate,
[4] A dye-sensitized solar cell electrode comprising the conductive film according to [2] or the conductive film according to [3],
I will provide a.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the electrically conductive film which can manufacture the electrically conductive film excellent in electroconductivity and film | membrane intensity | strength can be provided. Moreover, according to this invention, the electrode for dye-sensitized solar cells provided with the said electrically conductive film, the electroconductive film provided with the said electrically conductive film, and the said electrically conductive film or the said electroconductive film can be provided.

1. Manufacturing method of conductive film The manufacturing method of the conductive film of the present invention is that carbon monoxide desorption amount is 1000 to 10000 μmol / g at 150 to 950 ° C. in the temperature programmed desorption method, and carbon dioxide is desorbed. A step of preparing a dispersion containing carbon nanotubes in an amount of 500 to 5000 μmol / g, a step of forming a film from the dispersion, and a step of reducing the membrane by bringing it into contact with a reducing agent. To do.
Hereinafter, the carbon nanotubes used in the method for producing a conductive film of the present invention, the dispersion, the reducing agent, and the conductive film produced by the method will be described in detail.

(carbon nanotube)
Carbon nanotubes (hereinafter also referred to as “CNT”) used in the method for producing a conductive film of the present invention have a carbon monoxide (CO) desorption amount of 1000 to 150 ° C. in a temperature programmed desorption method. The desorption amount of carbon dioxide (CO ₂ ) is 500 to 5000 μmol / g.

CO and CO ₂ in the gas generated in the temperature programmed desorption method are variously bonded to the CNT surface, such as hydroxyl group, carboxyl group, ketone group, lactone group, aldehyde group and methyl group. Derived from a functional group. The CNT has the amount of CO and CO ₂ desorbed as described above, and it is presumed that many hydroxyl groups and carboxyl groups are present on the surface thereof. Since the CNT has such characteristics, it is excellent in dispersibility in various solvents, for example. In addition, it is possible to form a film having excellent conductivity and a very low volume resistivity. From the viewpoint of enhancing the effect of CNT used in the method for producing a conductive film of the present invention, the amount of CO desorption is preferably 1500 to 8000 μmol / g, more preferably 1800 to 6000 μmol / g, and CO ₂ desorption. The amount is preferably 800 to 4000 μmol / g, more preferably 1000 to 3500 μmol / g.

The desorption amount of CO and CO ₂ in the temperature programmed desorption method can be determined by a known method. That is, first, heat treatment is performed on the CNTs in a predetermined temperature-programmed desorption device to desorb adsorbed water from the surface of the CNTs. Next, the heat-treated CNT is heated to a predetermined temperature in an inert gas such as helium gas, and is generated along with desorption of functional groups (oxygen-containing atomic compounds, etc.) from the surface of the CNT. Quantify CO and CO ₂ respectively.
The amount of CO desorption or CO ₂ desorption at 150 to 950 ° C. in the temperature-programmed desorption method is such that the CNT is heated to 150 ° C., and then the CNT is further heated so that the temperature is 950 ° C. It is determined as the total amount of CO or the total amount of CO ₂ that has been desorbed during the period until it rises.

The CNT is, for example, a surface of an arbitrary CNT that does not satisfy the desorption amount of CO and CO ₂ in the present invention (hereinafter sometimes referred to as “raw material CNT”), strong acid such as nitric acid, ozone, fluorine, etc. It can be manufactured by processing with gas or the like. The desorption amount of CO and CO ₂ can be adjusted by appropriately changing the processing conditions of CNT according to the following.
The method for producing a conductive film of the present invention increases the dispersibility of CNTs in a dispersion by using a CNT having a desorption amount of CO and CO ₂ within the specified range. A conductive film having high conductivity and high film strength can be produced.

[Raw material CNT]
The raw material CNT may be a single layer or a multilayer, but from the viewpoint of improving the performance (for example, conductivity and mechanical properties) of the obtained conductive film and conductive film. A single layer to five layers are preferable, and a single layer is more preferable.

  The average diameter (Av) and standard deviation (σ) of the diameter of the raw material CNT are usually 0.60> (3σ / Av)> 0.20, preferably 0.60> (3σ / Av)> 0. Those satisfying 50 are preferred. Here, the diameter means the outer diameter of the raw material CNT. The average diameter (Av) and the standard deviation of diameter (σ) are the average value and standard deviation when measuring the diameter of 100 randomly selected carbon nanotubes under observation with a transmission electron microscope. (The average length described later is also obtained as an average value by measuring the length in the same manner.) As the raw material CNTs, those having a normal distribution when the diameter measured in this way is plotted on the horizontal axis and the frequency is plotted on the vertical axis and approximated by Gaussian are usually used.

The average diameter (Av) of the raw material CNT is usually preferably 0.5 nm or more and 15 nm or less, and more preferably 1 nm or more and 10 nm or less.
Moreover, the average length of raw material CNT becomes like this. Preferably they are 0.1 micrometer-1 cm, More preferably, they are 0.1 micrometer-1 mm. When the average length of the raw material CNT is within the above range, the orientation of the CNT used in the production method of the present invention is enhanced, and the conductive film can be easily formed.

As the specific surface area of the raw material CNT, the BET specific surface area by nitrogen gas adsorption is usually 600 m ² / g or more, preferably 700 m ² / g or more, the upper limit is usually 2500 m ² / g, and water vapor The BET specific surface area by adsorption is usually 0.01 to 50 m ² / g, preferably 0.1 to 30 m ² / g. The ratio of the BET specific surface area by water vapor adsorption to the BET specific surface area by nitrogen gas adsorption (BET specific surface area by water vapor adsorption / BET specific surface area by nitrogen gas adsorption) is usually 0.0001 to 0.2, preferably 0.00. 0005 to 0.15. Those specific surface areas can be measured using, for example, “BELSORP (registered trademark) -max” (manufactured by Nippon Bell Co., Ltd.).
The CO desorption amount of the raw material CNT at 150 to 950 ° C. in the temperature programmed desorption method is usually 100 to 2000 μmol / g, and the CO ₂ desorption amount is usually 1 to 3000 μmol. / G.
When the specific surface area of the raw material CNT and the desorption amount of CO and CO ₂ are within the above ranges, the dispersibility of the CNT used in the method for producing a conductive film of the present invention is preferably increased.

The raw material CNT preferably has a plurality of micropores. Among them, it is preferable to have micropores having a pore size smaller than 2 nm, and the abundance thereof is a micropore volume determined by the following method, preferably 0.4 mL / g or more, more preferably 0.43 mL / g or more. More preferably, it is 0.45 mL / g or more, and the upper limit is usually about 0.65 mL / g. It is preferable from the viewpoint of improving the dispersibility of the CNT used in the method for producing a conductive film of the present invention that the raw material CNT has the above-described micropores. In addition, a micropore volume can be adjusted by changing suitably the preparation method and preparation conditions of raw material CNT, for example.
Here, the “micropore volume (Vp)” is a formula in which the nitrogen adsorption isotherm at the liquid nitrogen temperature (77 K) of SGCNT is measured, and the nitrogen adsorption amount at relative pressure P / P0 = 0.19 is V. I): Vp = (V / 22414) × (M / ρ). P is the measurement pressure at the time of adsorption equilibrium, P0 is the saturated vapor pressure of liquid nitrogen at the time of measurement, and in formula (I), M is the molecular weight of adsorbate (nitrogen) 28.010, and ρ is the adsorbate (nitrogen). ) At 77K with a density of 0.808 g / cm ³ . The micropore volume can be determined using, for example, “BELSORP (registered trademark) -mini” (manufactured by Nippon Bell Co., Ltd.).

As the raw material CNT having the above characteristics, it is preferable to use CNT obtained by the following super-growth method (hereinafter sometimes referred to as SGCNT).
SGCNT is, for example, on a substrate (hereinafter also referred to as “CNT production substrate”) having a carbon nanotube production catalyst layer (hereinafter also referred to as “CNT production catalyst layer”) on its surface. In addition, when a raw material compound and a carrier gas are supplied to synthesize carbon nanotubes by chemical vapor deposition (CVD), a small amount of oxidant is present in the system, so that the catalyst layer for CNT production In a method of dramatically improving catalyst activity (super growth method; see International Publication No. 2006/011655), a catalyst layer is formed on a substrate surface by a wet process, and acetylene as a main component is used as a raw material gas. By using a gas (for example, a gas containing 50% by volume or more of acetylene), it can be efficiently produced.

In the case of oxidizing the surface, a known oxidation method such as treatment with a strong acid such as nitric acid, a gas such as ozone or fluorine, or heating in an oxygen gas atmosphere may be performed in a timely manner.
[Nitric acid treatment]
When nitric acid is used for the treatment of the raw material CNT, the form of nitric acid to be used is not particularly limited as long as it includes nitric acid, and fuming nitric acid is also included. Usually, those having a purity of 5% or more, preferably 50% or more, more preferably 80% or more are used. Usually, 200 to 10,000 parts by mass of nitric acid is added to 100 parts by mass of the raw material CNT. At that time, the obtained mixture may be subjected to ultrasonic treatment to disperse the raw material CNT. The resulting mixture may then be heated. The heating method is not particularly limited as long as it is a commonly used method, but may be selected as appropriate, such as heating with an oil bath or mantle heater, or heating by irradiating microwaves. Heating may be performed under normal pressure or under pressure such as in an autoclave. In general, heating is performed at 30 to 120 ° C. for 0.1 to 50 hours in the case of normal pressure, and in the case of pressurization, the heating is performed at 30 to 200 ° C. for about 0.1 to 50 hours. On the other hand, heating by microwave irradiation is usually set at 30 to 120 ° C. for normal pressure, and 30 to 200 ° C. for pressurization, setting the microwave output so that the mixture is heated, Perform for about 0.01 to 24 hours. In either case, heating may be performed in one step or in two or more steps. Moreover, it is preferable to stir the said mixture by arbitrary stirring means at the time of a heating.
As described above, the surface of the raw material CNT is treated with nitric acid. Since the mixture after the treatment is very hot, it is cooled to room temperature. Next, nitric acid is removed by, for example, decantation, and the treated CNTs are washed with, for example, water. The cleaning is usually performed until the cleaning liquid becomes neutral.

By treating the surface of CNT with nitric acid, it is presumed that in addition to the oxygen-containing functional group, a nitro group (? NO ₂ ) binds to the surface of CNT. The presence of the nitro group greatly contributes to the improvement of the conductivity and dispersibility of the CNT used in the method for producing a conductive film of the present invention.

[Fluorine treatment]
When fluorine gas is used for the treatment of the raw material CNT, high-purity fluorine gas is preferably used. However, the fluorine concentration in the fluorine gas is usually 1% by mass or more, such as nitrogen, argon and helium. Even if diluted with an inert gas, fluorocarbons such as tetrafluoroethane and hexafluoroethane; inorganic fluorides such as hydrogen fluoride, nitrogen trifluoride and iodine pentafluoride; oxygen; water vapor, etc. May be included. From the viewpoint of increasing the production efficiency of CNTs used in the method for producing a conductive film of the present invention, the fluorine concentration in the fluorine gas is preferably 2% by mass or more, more preferably 10% by mass or more, and particularly preferably 99% by mass. That's it.

  The contact between the raw material CNT and the fluorine gas can be performed by a known method. For example, the raw material CNT may be sealed in a reactor made of a material having corrosion resistance to fluorine, such as nickel or an alloy containing nickel or graphite, and fluorine gas may be introduced and contacted.

  The pressure of the fluorine gas when contacting with the raw material CNT is usually 0.002 to 1.0 MPa, preferably 0.005 to 0.5 MPa. If it is this range, fluorine gas can be efficiently contacted with raw material CNT. As the reaction gas, it is preferable to use a high-purity fluorine gas diluted with an inert gas such as nitrogen or argon in terms of safety and reactivity control.

  The contact between the raw material CNT and the fluorine gas may be performed in a batch mode, a semi-batch mode in which the fluorine gas is intermittently replaced, or a flow mode. Moreover, it is preferable to provide an appropriate stirring mechanism in the reactor in order to bring the raw material CNT and fluorine gas into uniform contact. Examples of the stirring mechanism include stirring by various stirring blades, a method of mechanically rotating or vibrating the reactor, and a method of flowing the raw material CNT by flowing gas.

  The temperature at which the raw material CNT is brought into contact with the fluorine gas is usually in the range of 100 to 500 ° C. From the viewpoint of shortening the reaction time and efficiently reacting the carbon constituting the CNT and fluorine, the temperature is preferably 100 to 450 ° C, more preferably 200 to 400 ° C. The contact time depends on the contact method and contact conditions, but is not particularly limited, and may be set within a range of 10 seconds to 100 hours.

After contacting the raw material CNT with fluorine gas, the treated CNT is treated with water in order to remove unnecessary fluorine gas physically adsorbed on the obtained treated CNT and hydrogen fluoride (HF) generated upon contact. Wash. Washing is performed, for example, by adding a sufficient amount of water to the treated CNTs, stirring appropriately at room temperature, and then filtering, until the fluorine is substantially not detected in the washing waste water.
Through the above steps, CNTs usable in the method for producing a conductive film of the present invention are obtained.

In the manufacturing method of the electrically conductive film of this invention, you may add a metal nanostructure with the said CNT. The metal nanostructure is a microstructure made of a metal or a metal compound and refers to a conductive material.
Alternatively, a metal may be supported on the CNT and added in the form of a metal composite material. The metal composite material is a composite of CNT and a metal that can be plated, and by using this, the conductivity of the manufactured conductive film can be increased.
Examples of the metal used in the metal nanostructure or the metal composite material include copper, nickel, tin, platinum, chromium, zinc, and composite metals thereof. The copper which it has can be used conveniently.

(Dispersion)
The dispersion of the present invention comprises the CNT. Since the CNTs are excellent in dispersibility in a solvent, a dispersant is not required for producing the dispersion. Therefore, the dispersion liquid usually consists of the CNT and a solvent.

  Solvents used for preparing the dispersion include water; alcohols such as methanol, ethanol and propanol; ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran, dioxane and diglyme; N, N-dimethylformamide, N, N -Amides such as dimethylacetamide, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone; sulfur-containing solvents such as dimethyl sulfoxide and sulfolane; and the like. These solvents can be used alone or in combination of two or more.

  The dispersion may contain a binder, a conductive aid, a dispersant, a surfactant and the like as desired. These may be appropriately known ones.

The dispersion can be obtained, for example, by mixing the CNTs in a solvent and dispersing the CNTs.
For the mixing process and dispersion process, for example, a method using a nanomizer, an optimizer, an ultrasonic disperser, a ball mill, a sand grinder, a dyno mill, a spike mill, a DCP mill, a basket mill, a paint conditioner, a high-speed stirring device, or the like may be used. .

The content of the CNT in the dispersion is not particularly limited, but is preferably 0.001 to 10% by mass.
In the dispersion, CNTs are uniformly dispersed, and are suitable for manufacturing a conductive film of CNTs.

(Conductive film)
The conductive film of the present invention is produced by reducing a film formed with the dispersion containing the CNTs with a reducing agent. The thickness of the conductive film is usually in the range of 5 nm to 100 μm. The conductive film may be a long continuous sheet. The specific gravity of the conductive film is usually preferably from 0.3 to 3.0 g / cm ³ .

(Each process of the manufacturing method of an electrically conductive film)
Hereinafter, each process for producing a conductive film from the dispersion will be described.
[Deposition process of unreduced film]
In the process for producing a conductive film of the present invention, first, the dispersion is applied on, for example, an arbitrary support, and the obtained coating film is dried to form an unreduced film. When the support is porous, the dispersion may be filtered through the support and the obtained filtrate may be dried.
The unreduced membrane may be subjected to a reduction process described later with the support added, or may be subjected to a reduction process described below with the support removed.

  The support is not particularly limited as long as it can sufficiently fix the film during the production of the non-reduced film and can be easily removed after the film is formed. Examples thereof include synthetic resin sheets such as PTFE (polytetrafluoroethylene) sheets and PET (polyethylene terephthalate) sheets, and porous sheets such as cellulose, nitrocellulose, filter paper, and alumina.

  When applying the dispersion on the support, a known application method can be employed. Examples of the coating method include a dipping method, a roll coating method, a gravure coating method, a knife coating method, an air knife coating method, a roll knife coating method, a die coating method, a screen printing method, a spray coating method, and a gravure offset method.

  When drying the obtained coating film or filtration thing, a well-known drying method is employable. Examples of the drying method include a hot air drying method, a hot roll drying method, and an infrared irradiation method. The drying temperature is not particularly limited, but is usually room temperature to 200 ° C., and the drying time is not particularly limited, but is usually 0.1 to 150 minutes. The dry atmosphere may be selected as appropriate, such as in air, in an inert gas such as nitrogen or argon, or in a vacuum.

  By forming the unreduced film with the dispersion, the conductive film of the present invention to be produced can be obtained as containing no dispersant. Therefore, it is not necessary to remove the dispersant in order to increase the conductivity, and the conductive film of the present invention is excellent in conductivity as it is.

  As the unreduced film, a film using SGCNT is particularly preferable. As described above, the average diameter (Av) of SGCNT is preferably 0.5 nm or more and 15 nm or less. Moreover, the average length becomes like this. Preferably they are 0.1 micrometer-1 cm. When the non-reduced film is formed using SGCNT having such shape characteristics, a conductive film having a structure in which carbon nanotubes cross each other to form a network structure can be easily obtained.

[Reduction process of unreduced film]
Next, the non-reduced film is reduced using a reducing agent to form the conductive film of the present invention. Although it does not restrict | limit especially as a reducing agent, For example, the heating in a borohydride compound, a metal hydride, an organic reduction solvent, hydrogen gas, or inert gas etc. are mentioned. Examples of the borohydride compound include sodium borohydride, tetrabutylammonium borohydride, sodium trimethoxyborohydride, and mixtures thereof. Examples of the metal hydride include borohydride metal hydride, aluminum hydride, sodium hydride, diisobutylaluminum hydride, lithium aluminum hydride and the like, preferably sodium hydride, diisobutylaluminum hydride, hydrogen Lithium aluminum halide. These metal hydrides may be used alone or as a mixture thereof. When reducing CNTs using hydrogen gas, it is preferable to use a transition metal catalyst or to proceed the reduction reaction at a high temperature. The organic reducing solvent according to an embodiment of the present invention is not particularly limited, and examples thereof include hydrazine (NH ₂ NH ₂ ), glycol-based solvents, diol-based solvents, and mixtures thereof. Here, specific examples of the glycol solvent are not particularly limited, but preferred examples include ethylene glycol, diethylene glycol, and triethylene glycol. Specific examples of the diol solvent are not particularly limited, but 1,3-propanediol, 1,3-butanediol and the like are preferable.

  The unreduced film is reacted with the reducing agent, and the unreduced film is reduced to form a conductive film. The amount of the reducing agent is not particularly limited, but is preferably 0.003 to 3000% by mass and more preferably 0.03 to 500% by mass with respect to CNT. The specific amount of the reducing agent varies depending on the type of the reducing agent.

  The reaction time and reaction temperature between the reducing agent and the unreduced film are not particularly limited, but it is preferable to react at 25 to 300 ° C. for 1 to 24 hours. The specific temperature and time vary depending on the type of reducing agent. The reduction of the unreduced film is measured by comparing the peak intensity corresponding to C = O and COOH on the film surface using, for example, an X-ray photoelectron analyzer (XPS) before and after the reduction process. It can be confirmed with. After the reduction step, the peak intensity decreases.

  When the unreduced film is subjected to a reduction process with a support added, the conductive film of the present invention can be obtained by peeling the reduced film from the support.

  According to the method for producing a conductive film of the present invention, an unreduced film having high film strength can be obtained by forming a film using highly dispersible CNTs, and further, the conductive film can be made conductive by reducing the unreduced film. A highly conductive film can be formed.

2. Conductive film A predetermined base material is prepared for the conductive film, and the base film is pressure-bonded to the base material by hot pressing or the like to form a conductive film comprising the conductive film of the present invention on the base material. be able to. In this case, the conductive film may be pressure-bonded to the substrate without being peeled from the support used at the time of forming the non-reduced film, and the support may be peeled off from the conductive film after pressure bonding.
Alternatively, a predetermined base material or the like is used as a support, the dispersion liquid is applied thereon, and the obtained coating film is dried and reduced to provide the conductive film of the present invention on the base material. A conductive film may be formed.

  The substrate is not particularly limited, and a known substrate can be used depending on the use of the conductive film to be produced. Specifically, for example, when the obtained conductive film is used as a transparent conductive film, examples of the substrate include a resin substrate and a glass substrate. Resin base materials include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyimide, polyphenylene sulfide, aramid, polypropylene, polyethylene, polylactic acid, polyvinyl chloride, polycarbonate, polymethyl methacrylate, and alicyclic. The base material which consists of an acrylic resin, a cycloolefin resin, a triacetyl cellulose etc. can be mentioned. Examples of the glass substrate include a substrate made of ordinary soda glass.

3. Product using conductive film Here, the conductive film of the present invention was prepared using a dispersant, so that CNTs were well dispersed in the conductive film, and were prepared through a cleaning process and a decomposition process. Therefore, the content of the dispersant is reduced. Therefore, the conductive film of the present invention is excellent in transparency because desired conductivity and mechanical properties can be obtained even if the CNT content is low. That is, the electrically conductive film of this invention can be used especially suitably as transparent electrically conductive films, such as a solar cell and a touch panel.
In addition, the electrically conductive film of this invention can also be used for various products, after laminating | stacking known functional layers, such as an overcoat layer arbitrarily. Here, lamination of a functional layer such as an overcoat layer on the conductive film can be performed using a known technique.

(Touch panel)
Specifically, the conductive film of the present invention can be suitably used as a conductive layer that is formed on a transparent substrate and constitutes a touch sensor of a touch panel such as a capacitive touch panel.

(Solar cell)
Moreover, the electrically conductive film of this invention can be used as a conductive layer and a catalyst layer which comprise the electrode of solar cells, such as a dye-sensitized solar cell. More specifically, the conductive film of the present invention includes a conductive layer constituting a photoelectrode of a dye-sensitized solar cell, a conductive layer constituting a counter electrode (catalyst electrode) of the dye-sensitized solar cell, and / or It can be used as a catalyst layer.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples. The physical properties were evaluated by the following methods.

(1) Evaluation by temperature-programmed desorption method A conductive film was placed on a fully automatic temperature-programmed desorption spectrometer “TPD-1-ATw” manufactured by Bell Japan, and carrier gas (He) was circulated at 50 mL / min. . The amount of CO and CO ₂ desorbed was raised from 150 ° C. to 950 ° C. at a rate of temperature increase of 5 ° C./min to heat the conductive film, and the CO and CO ₂ produced during that time were measured using a quadrupole mass spectrometer. The amount of gas (μmol) generated from 1 g of CNTs was calculated from the gas amounts of CO and CO ₂ obtained, and the amounts of CO and CO ₂ desorbed were determined, respectively.
(2) Dispersibility 0.001 g of CNT was added to 5 mL of ion-exchanged water or ethanol and dispersed for 60 minutes with an ultrasonic disperser, and the dispersibility was visually evaluated according to the following evaluation criteria.
〔Evaluation criteria〕
○: No visible agglomerates existed x: Visible agglomerates existed (3) Volume resistivity Four terminals by conductivity meter (product name “Loresta (registered trademark) GP” manufactured by Mitsubishi Analitech Co., Ltd.) Measured by the method.
〔Evaluation criteria〕
○: conductivity improved after reduction ×: conductivity decreased after reduction

(Preparation of CNT)
SGCNT was prepared by the super-growth method according to the description of WO 2006/011655.
The obtained SGCNT was mainly composed of single-walled CNTs, and had a BET specific surface area of 800 m ² / g and a micropore volume of 0.44 mL / g. The average diameter (Av) was 3.3 nm, the diameter distribution (3σ) was 1.9 nm, (3σ / Av) was 0.58, and the average length was 500 μm.

[Example: Preparation of conductive film]
A thermometer, a water flow reflux condenser and a stirrer were attached to a 500 mL three-necked flask, and 1 g of the above SGCNT and 80 mL of nitric acid (Tokyo Kasei Co., Ltd., purity 69%) were added to the flask. The three-necked flask was heated in a 130 ° C. oil bath, and the reaction was carried out by heating and stirring for 6 hours after the internal temperature reached a reflux state of 130 ° C. After completion of the reaction, the reaction mixture was allowed to cool to room temperature, ion exchange water was added, the supernatant was removed by decantation, and ion exchange water was further added. The addition and decantation of ion-exchanged water were repeated until the supernatant (washing solution) to be removed became neutral (pH = 6.8) to obtain 21.3 g of nitric acid-treated SGCNT in a wet state.
In a 30 mL glass bottle, a 1% aqueous ammonia solution added to 10 mL of the nitric acid-treated SGCNT so as to be 0.05% by mass is subjected to a dispersion treatment at room temperature for 30 minutes in an ultrasonic bath (BRANSON). A dispersion was obtained.
The obtained dispersion was applied to a PET film (hydrophilized, manufactured by Toyobo) using a bar coater (# 6), placed in an oven at 80 ° C., and dried for 5 minutes. After drying, it was removed from the oven and the conductivity was measured.
The dried film is reduced by heating in a hydrazine (NH ₂ NH ₂ ) gas atmosphere at 80 ° C. for 20 minutes after being heat-treated at 100 ° C. for 30 minutes in a vacuum (0.1 Torr) with a hot plate. did. Thereafter, the conductivity was measured. Table 1 shows the measured values.

[Comparative example]
In the examples, a film was formed in the same manner as in the example except that the SGCNT was not oxidized with nitric acid, and the conductivity of the film before and after the reduction was measured. Table 1 shows the measured values.

From Table 1, it was found that the post-treatment SGCNT obtained in the examples showed a predetermined amount of CO and CO ₂ desorption in the present invention, and showed good dispersibility in the dispersion. In addition, although the film of the comparative example did not show a significant change in the conductivity before and after the reduction process, the conductive film of the example sufficiently improved the conductivity of the conductive film before and after the reduction process. It was observed.

The conductive film and conductive film of the present invention are suitably used as constituent materials for electrodes used in electronic devices and electronic members such as touch panels, solar cells, and fuel cells.

Claims (4)

  A dispersion containing carbon nanotubes having a carbon monoxide desorption amount of 1000 to 10000 μmol / g and a carbon dioxide desorption amount of 500 to 5000 μmol / g at 150 to 950 ° C. in a temperature programmed desorption method. The manufacturing method of the electrically conductive film including the process of preparing, the process of forming a film | membrane from the said dispersion liquid, and the process of making the said film | membrane contact and reducing.   The electrically conductive film manufactured by the manufacturing method of Claim 1.   The electroconductive film provided with the electrically conductive film of Claim 2 on the base material. The electrode for dye-sensitized solar cells provided with the electrically conductive film of Claim 2, or the electroconductive film of Claim 3.