JP2015210955A - Method of producing conductive coating, and conductive coating, conductive film, electrode for solar battery and solar battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of producing a conductive coating that makes it possible to produce a conductive coating having excellent conductivity and reliability.SOLUTION: A method of producing a conductive coating comprises a step of bringing a coating comprising carbon nanotubes, where an average diameter (Av) and a diameter standard deviation (σ) satisfy the relational expression: 0.60>3σ/Av>0.20, and a p-type dopant into contact with each other.

Description

  The present invention relates to a method for producing a conductive film, and particularly relates to a method for producing a conductive film containing carbon nanotubes. Moreover, this invention relates to the electrically conductive film manufactured using the manufacturing method of the said electrically conductive film, the electroconductive film provided with the said electrically conductive film, the electrode for solar cells using the said electrically conductive film, or the said electroconductive film, and a solar cell. Is.

  In recent years, carbon nanotubes (hereinafter sometimes referred to as “CNT”) have attracted attention as carbon materials having excellent characteristics such as conductivity, and a technique for improving the performance of various products by using CNTs. Has been proposed. Specifically, for example, regarding a conductive film used in a solar cell, a technique for improving the conductivity of the conductive film by blending CNTs has been proposed. In recent years, further enhancement of performance of products such as solar cells has been promoted, and a film containing CNT (hereinafter referred to as a “CNT-containing film”) may be used in the production of a conductive film as these materials. .)), A technique for improving the conductivity of the conductive film has been studied.

For example, Patent Document 1 discloses that a chloroauric acid aqueous solution with a predetermined concentration is brought into contact with an untreated conductive layer formed on a base material and containing a carbon nanotube having a hydrophilic group introduced therein and a dispersant for a predetermined time. A technique for reducing the surface resistance value of the obtained conductor has been proposed.
Patent Document 2 proposes a technique for improving conductivity by doping a carbon nanotube film with an oxidizing solution containing an oxidizing agent and an organic solvent.

JP 2013-45695 A JP 2008-297196 A

However, the conductive film obtained by using the above conventional technique is not yet sufficiently conductive, and the reliability (storage stability) is not satisfactory.
Therefore, the conventional method for producing a conductive film still has room for improvement in terms of further improving the conductivity and reliability of the conductive film.

Then, an object of this invention is to provide the manufacturing method of the electrically conductive film which can manufacture the electrically conductive film which is excellent in electroconductivity and reliability.
Moreover, this invention provides the electrically conductive film which is excellent in electroconductivity and reliability, the electroconductive film provided with the said electrically conductive film, the electrode for solar cells using the said electrically conductive film, or the said electrically conductive film, and a solar cell. With the goal.

  The present inventors have intensively studied to achieve the above object. Then, the present inventors only have high conductivity by performing a doping treatment using a specific dopant on a film containing carbon nanotubes in which the average diameter and the standard deviation of the diameter satisfy a specific relational expression. In addition, the inventors have found that a conductive film having excellent reliability can be manufactured, and completed the present invention.

That is, the present invention aims to advantageously solve the above-mentioned problems, and the method for producing a conductive film of the present invention has an average diameter (Av) and a standard deviation (σ) of the diameter as a relational expression: It is characterized by comprising a step of contacting a film containing carbon nanotubes satisfying 0.60> 3σ / Av> 0.20 and a p-type dopant. In this manner, a conductive film having excellent conductivity and reliability can be manufactured by bringing a thin film containing CNT having 3σ / Av of more than 0.20 and less than 0.60 into contact with a p-type dopant.
In the present invention, “average diameter (Av) of carbon nanotubes” and “standard deviation of carbon nanotube diameter (σ: sample standard deviation)” are carbons selected at random using a transmission electron microscope, respectively. It can be obtained by measuring the diameter (outer diameter) of 100 nanotubes.

  Here, in the manufacturing method of the electrically conductive film of this invention, it is preferable that the said p-type dopant contains at least one of gold trichloride and chloroauric acid. This is because if at least one of gold trichloride and chloroauric acid is used as the p-type dopant, the conductivity and reliability of the obtained conductive film can be further improved.

Moreover, in the manufacturing method of the electrically conductive film of this invention, it is preferable that the average length of the said carbon nanotube is 0.1 micrometer or more and 10 mm or less. This is because if the CNT having an average length of 0.1 μm or more and 10 mm or less is used for forming the conductive film, the conductivity and reliability of the obtained conductive film can be further improved.
In the present invention, the “average length of carbon nanotubes” can be obtained by measuring the length of 100 carbon nanotubes selected at random using a transmission electron microscope.

  And the electrically conductive film of this invention is manufactured by either of the manufacturing methods of the electrically conductive film mentioned above, It is excellent in electroconductivity and reliability.

Furthermore, the conductive film of the present invention includes a base film and a conductive film on the base film, and the conductive film is the conductive film described above. Since the conductive film of the present invention includes the conductive film of the present invention, it has excellent conductivity and reliability.
The conductive film of the present invention preferably has a surface resistivity of 0.01Ω / □ or more and 10 ⁴ Ω / □ or less.

  In addition, the solar cell electrode of the present invention is formed using the conductive film of the present invention or the conductive film of the present invention, and the solar cell of the present invention includes the solar cell electrode of the present invention. It is characterized by that.

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 reliability can be provided.
Moreover, according to this invention, the electrically conductive film which is excellent in electroconductivity and reliability, the electroconductive film using the said electrically conductive film, the electrode for solar cells using the said electrically conductive film, or the said electroconductive film, and a solar cell. Can be provided.

Hereinafter, embodiments of the present invention will be described in detail.
Here, the manufacturing method of the electrically conductive film of this invention can be used when manufacturing the electrically conductive film which is excellent in electroconductivity and reliability containing CNT. And the electrically conductive film manufactured using the manufacturing method of the electrically conductive film of this invention and an electrically conductive film provided with the said electrically conductive film are not specifically limited, It can be used for various products, such as an electrode for solar cells, and a solar cell. it can.

(Manufacturing method of conductive film)
The conductive film manufacturing method of the present invention includes a film containing carbon nanotubes having an average diameter (Av) and a standard deviation (σ) of a diameter satisfying a relational expression: 0.60> 3σ / Av> 0.20, p One of the major features is to provide a step of contacting the type dopant. And according to the manufacturing method of the electrically conductive film of this invention, the electrically conductive film which is excellent in electroconductivity and reliability can be manufactured.

<Carbon nanotube-containing film>
The CNT-containing film used in the present invention is a film containing at least CNT. Hereinafter, CNT contained in the CNT-containing film, optional additives, and a method for forming the CNT-containing film will be described in detail.

[carbon nanotube]
As the CNT, a CNT having a ratio (3σ / Av) of a value (3σ) obtained by multiplying the standard deviation (σ) of the diameter by 3 with respect to the average diameter (Av) is more than 0.20 and less than 0.60. It is more preferable to use CNTs with 3σ / Av exceeding 0.25, and it is even more preferable to use CNTs with 3σ / Av exceeding 0.50. If 3CNT / Av is more than 0.20 and less than 0.60, the dispersibility of the CNT will be improved, and the conductivity and reliability of the conductive film will be sufficiently enhanced even with a small amount of CNT. Can do. Therefore, it is possible to obtain a transparent conductive film excellent in conductivity, reliability, and transparency by reducing the amount of CNTs necessary for obtaining a conductive film having desired conductivity and reliability.
The average diameter (Av) and standard deviation (σ) of CNTs may be adjusted by changing the CNT manufacturing method and manufacturing conditions, or by combining multiple types of CNTs obtained by different manufacturing methods. May be.

  In the present invention, as the CNT, the diameter measured as described above is plotted on the horizontal axis and the frequency is plotted on the vertical axis. The

  The CNT is not particularly limited, and single-walled carbon nanotubes and / or multi-walled carbon nanotubes can be used. The CNTs are preferably single-walled to carbon-walled carbon nanotubes. More preferably, it is a nanotube. If single-walled carbon nanotubes are used, the conductivity and reliability of the conductive film can be improved as compared with the case where multi-walled carbon nanotubes are used.

  Furthermore, the CNT preferably has a peak of Radial Breathing Mode (RBM) when evaluated using Raman spectroscopy. Note that there is no RBM in the Raman spectrum of multi-walled carbon nanotubes of three or more layers.

  CNTs preferably have a ratio of G band peak intensity to G band peak intensity (G / D ratio) in the Raman spectrum of 1 or more and 20 or less. When the G / D ratio is 1 or more and 20 or less, the conductivity and reliability of the conductive film can be sufficiently improved even if the amount of CNT is small. Therefore, it is possible to obtain a transparent conductive film excellent in conductivity, reliability, and transparency by reducing the amount of CNTs necessary for obtaining a conductive film having desired conductivity and reliability.

  Furthermore, the average diameter (Av) of CNTs is preferably 0.5 nm or more, more preferably 1 nm or more, preferably 15 nm or less, and more preferably 10 nm or less. If the average diameter (Av) of CNT is 0.5 nm or more, it is possible to obtain a conductive film having excellent conductivity and reliability by suppressing CNT aggregation and improving the dispersibility of CNT in the CNT-containing film. . Moreover, if the average diameter (Av) of CNT is 15 nm or less, the electrically conductive film which is excellent in electroconductivity and reliability can be obtained.

  The average length of the CNTs is preferably 0.1 μm or more, more preferably 10 μm or more, preferably 10 mm or less, and more preferably 1 mm or less. When the average length of CNTs is 0.1 μm or more and 10 mm or less, it is possible to improve the dispersibility of CNTs in the CNT-containing film and obtain a conductive film having excellent conductivity and reliability.

Further, the specific surface area of the CNT is preferably 100 m ² / g or more, and preferably 2500 m ² / g or less. When the CNT is mainly unopened, the specific surface area is preferably 600 m ² / g or more, more preferably 800 m ² / g or more, and preferably 1200 m ² / g or less. In addition, in the case where CNTs are mainly opened, the specific surface area is preferably 1300 m ² / g or more. When the specific surface area of CNT is 100 m ² / g or more, the conductivity and reliability of the conductive film can be sufficiently improved. In addition, when the specific surface area of CNT is 2500 m ² / g or less, it is possible to obtain a conductive film having excellent conductivity and reliability by suppressing CNT aggregation and improving the dispersibility of CNT in the CNT-containing film. .
In the present invention, the “specific surface area” refers to the nitrogen adsorption specific surface area measured using the BET method.

The mass density of the CNT is preferably at most 0.002 g / cm ³ or more 0.2 g / cm ^3. If the mass density is 0.2 g / cm ³ or less, the connection between the CNTs becomes weak, so that the CNTs can be uniformly dispersed to obtain a conductive film having excellent conductivity and reliability. In addition, if the mass density is 0.002 g / cm ³ or more, the integrity of the CNTs can be improved and the variation can be suppressed, so that handling becomes easy.

Furthermore, the CNT preferably has a plurality of micropores. Among them, the CNT preferably has micropores having a pore size smaller than 2 nm, and the abundance thereof is preferably a micropore volume, preferably 0.40 mL / g or more, more preferably 0.43 mL / g or more, Preferably, it is 0.45 mL / g or more, and the upper limit is usually about 0.65 mL / g. Since the CNTs have the above micropores, aggregation of the CNTs is suppressed, the dispersibility of the CNTs in the CNT-containing film is increased, and a conductive film having excellent conductivity and reliability can be efficiently obtained. . The micropore volume can be adjusted, for example, by appropriately changing the CNT preparation method and preparation conditions.
Here, the “micropore volume (Vp)” is a formula in which the nitrogen adsorption isotherm at the liquid nitrogen temperature (77 K) of CNT is measured and the nitrogen adsorption amount at relative pressure P / P0 = 0.19 is V. I): Vp = (V / 22414) × (M / ρ). Here, P is a measurement pressure at the time of adsorption equilibrium, P0 is a saturated vapor pressure of liquid nitrogen at the time of measurement, and in formula (I), M is an adsorbate (nitrogen) molecular weight of 28.010, and ρ is an adsorbate (nitrogen). ) At 77K with a density of 0.808 g / cm ³ . The micropore volume can be easily determined using, for example, “BELSORP (registered trademark) -mini” (manufactured by Nippon Bell Co., Ltd.).

  The CNT having the above-described properties is obtained by supplying a raw material compound and a carrier gas onto a base material having a catalyst layer for CNT production on the surface (hereinafter, also referred to as “CNT production base material”), for example. When synthesizing CNTs by chemical vapor deposition (CVD), the catalytic activity of the catalyst layer for CNT production is dramatically increased by the presence of a small amount of oxidizing agent (catalyst activation material) in the system. In a method of improving (super growth method; see International Publication No. 2006/011655), a catalyst layer is formed on the surface of a substrate by a wet process, and a source gas containing acetylene as a main component (for example, 50 volumes of acetylene) %), It can be produced efficiently. Hereinafter, the carbon nanotube obtained by the super growth method may be referred to as “SGCNT”.

[Optional additives]
As optional additives, known dispersants such as carboxymethyl cellulose or a salt thereof, fillers, stabilizers, colorants, charge control agents, lubricants, metal nanoparticles, etc., depending on the use of the conductive film to be formed. Additives can be used.
Here, a dispersing agent is used in order to promote dispersion | distribution in the dispersion liquid of CNT. From the viewpoint of improving the dispersibility of CNTs and improving the conductivity and reliability of the resulting conductive film in a well-balanced manner, the ratio of the amount of dispersant to the amount of CNT in the CNT-containing film (dispersant / CNT) is It is usually 0 to 20, preferably 0.01 to 10, more preferably 0.05 to 5, and particularly preferably 0.1 to 2 on a mass basis.

[Method for forming carbon nanotube-containing film]
The method for producing the CNT-containing film is not particularly limited, and a known film forming method can be used. For example, the CNT-containing film is formed by using the CNT dispersion liquid obtained by dispersing and / or dissolving the above-described CNT and an optional additive in a dispersion medium, using the following methods (i) and (ii). be able to.
(i) A method of applying a CNT dispersion onto a substrate film, removing the dispersion medium from the applied CNT dispersion, and obtaining a CNT-containing film laminated on the substrate film.
(ii) Applying the CNT dispersion onto the support for peeling, removing the dispersion medium from the applied CNT dispersion to form a CNT-containing film with a support, and then from the optionally obtained CNT-containing film with a support A method for obtaining a CNT-containing film by peeling a peeling support.
The CNT-containing film formed through the above-described CNT-containing film formation method (i) or (ii) usually contains CNT and optional additives in the same ratio as the CNT dispersion. .

[[Dispersion medium]]
The dispersion medium of the CNT dispersion is not particularly limited, and examples thereof include water; methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, t-butanol, pentanol, hexanol, heptanol, octanol, Alcohols such as nonanol, decanol and amyl alcohol; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; esters such as ethyl acetate and butyl acetate; ethers such as diethyl ether, dioxane and tetrahydrofuran; N, N- Amide polar organic solvents such as dimethylformamide and N-methylpyrrolidone; Aromatic hydrocarbons such as toluene, xylene, chlorobenzene, orthodichlorobenzene and paradichlorobenzene; And the like. These may be used alone or in combination of two or more. Of these, water is preferred.

[[Preparation of CNT dispersion]]
The CNT dispersion is prepared by mixing the above-described CNT, dispersion medium, and optional additives with a known mixing and dispersing machine (for example, ball mill, bead mill, sand mill, roll mill, homogenizer, ultrasonic homogenizer, high-pressure homogenizer, jet mill, ultrasonic device, atomizer. It can be produced by mixing using a lighter, resolver, paint shaker, etc.
The content of CNT in the CNT dispersion is not particularly limited, but is preferably 0.001 to 10% by mass.

[[Method for forming CNT-containing film (i)]]
The base film to which the CNT dispersion is applied when forming the CNT-containing film is not particularly limited, and a known base film can be used according to 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 base film include a resin base and a glass base. 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. Among these substrate films, a glass substrate is preferable and a substrate made of soda glass is more preferable from the viewpoint of improving conductivity and reliability.

And the surface of the base film is treated according to a known method such as treatment by UV irradiation, treatment by corona discharge or treatment by ozone, treatment by application of a silane coupling agent, acrylic resin or urethane resin, etc. It may be. By treating the surface of the substrate film in such a manner, it is possible to control the adhesion to the conductive film, the wettability of the CNT dispersion, and the like. In addition, for example, on the resin substrate and the glass substrate described above, a hard coat layer, a gas barrier layer, a pressure-sensitive adhesive layer, and a conductive layer (conductive film) other than that formed by the method of the present invention are provided. It may be. Although the thickness of a base film should just be determined suitably according to a use, it is 10-10000 micrometers normally.
Moreover, when forming a conductive film on a base film and using it as a transparent conductive film as it is, the light transmittance (measurement wavelength: 500 nm) of the base film is preferably 60% or more. .
In addition, the light transmittance (measurement wavelength: 500 nm) of a base film can be measured, for example using a spectrophotometer (JASCO Corporation V-570).

  As a method for applying the CNT dispersion on the base film, a known application method can be employed. Specifically, the coating method includes casting method, dipping method, roll coating method, gravure coating method, knife coating method, air knife coating method, roll knife coating method, die coating method, screen printing method, spray coating method, gravure offset. The law etc. can be used.

As a method for removing the dispersion medium from the CNT dispersion applied on the base film, a known drying method can be employed. Examples of the drying method include a hot air drying method, a vacuum 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 thickness of the CNT-containing film obtained after removing the dispersion medium is not particularly limited, but is usually from 100 nm to 1 mm. Further, the content of the carbon nanotubes contained in the CNT-containing film is not particularly limited, but is usually 0.1 × 10 ^{−6 to} 15 mg / cm ² .

[[Method for forming CNT-containing film (ii)]]
As a peeling support for applying a CNT dispersion when forming a CNT-containing film, a CNT-containing film or a conductive film can be sufficiently fixed thereon, and a CNT-containing film can be formed using a thin film peeling method. There is no particular limitation as long as the film or the conductive film can be peeled off from the peeling support. Examples thereof include synthetic resin sheets such as PTFE (polytetrafluoroethylene) sheets and PET (polyethylene terephthalate) sheets, membrane filters made of nitrocellulose, and the like.
The thickness of the peeling support may be appropriately determined, but is usually 10 to 10,000 μm.

The CNT-containing film obtained on the peeling support can be peeled from the peeling support by using a known thin film peeling method. For example, when the peeling support is dissolved in a predetermined solvent, the CNT-containing film alone can be taken out by immersing the CNT-containing film with the peeling support in the solvent.
The peeling from the peeling support may be performed at the stage of the CNT-containing film as described above, or may be performed after the doping process and after forming the conductive film of the present invention.

  As a method of applying the CNT dispersion liquid on the peeling support and a method of removing the dispersion medium from the CNT dispersion liquid coated on the peeling support, [[CNT-containing film forming method (i)]] The method described above in the section can be adopted.

  The CNT-containing film is usually composed of a single layer, but it is also possible to repeat the application of the CNT dispersion and the removal of the dispersion medium as appropriate to form two or more layers. Further, a CNT-containing film may be obtained, and the dispersant may be appropriately removed from the film by a known method.

<P-type dopant>
The p-type dopant is not particularly limited, and examples thereof include halogen oxoacid compounds, sulfur oxoacid compounds, metal halides, cerium ammonium compounds, nitrogen oxoacid compounds, metal oxoacid compounds, and benzoquinone compounds. Examples thereof include compounds, tetracyanoquinodimethane compounds, O ₃ and H ₂ O ₂ .
Examples of the halogen oxo acid compounds include iodobenzene, 2-iodoxybenzoic acid, des-martin periodinane, sodium hypochlorite, sodium chlorite, sodium chlorate, sodium perchlorate, silver chlorate, Halogen oxoacids such as silver chlorate and / or salts thereof.
Examples of the sulfur oxo acid compound include dimethyl sulfoxide (DMSO), H ₂ SO ₄ , KHSO ₅ , KHSO ₄ , K ₂ SO ₄ , FSO ₃ H, CF ₃ SO ₃ H, NH (CF ₃ SO ₃ H), AgN. (CF ₃ SO ₃ H).
Examples of the metal halide include FeCl ₃ , MoCl ₅ , WCl ₅ , SnCl ₄ , MoF ₅ , RuF ₅ , TaBr ₅ , SnI ₄ , HAuCl ₄ , AuCl _{3 and the} like.
Examples of the cerium ammonium compound include (NH ₄ ) ₂ Ce (SO ₄ ) ₃ and (NH ₄ ) ₂ Ce (NO ₃ ) ₆ .
As the nitrogen oxo acid compound, nitric acid and its salt, nitrogen dioxide compound or nitrogen oxide compound can be used. Specifically, NaNO ₂ , AgNO ₃ , NO ₂ F, NO ₂ Cl, N ₂ O ₅ NO ₂ BF ₄ , CH ₃ NO ₂ , C ₆ H ₅ NO ₂ , CH ₃ ONO, NO (SbCl ₆ ), NOBF ₄ , NOClO ₄ , NOSO ₄ H, C ₆ H ₅ NO, NOCl, NOF, NOBr, etc. Is mentioned.
As the metal oxo acid compound, a metal oxo acid, a salt thereof, and a metal oxide can be used. Specific examples include KMnO ₄ , BaMnO ₄ , and OsO ₄ .
Examples of the benzoquinone compounds include dichlorodicyanobenzoquinone such as benzoquinone, tetrachlorobenzoquinone, and 2,3-dichloro-5,6-dicyano-p-benzoquinone.
Examples of the tetracyanoquinodimethane compound include tetracyanoquinodimethane, tetrafluorotetracyanoquinodimethane, 2,5-bis (2-hydroxyethoxy) -7,7,8,8-tetracyanoquinodimethane, Bis (tetrabutylammonium) tetracyanodiphenoquinodimethanide, 2,5-dimethoxy-7,7,8,8-tetracyanonaphth-2,6-quinodimethane, tetracyanoethylene, 11, 11, 12, 12- Tetracyanonaphtho-2,6-quinonedimethane, 2-fluoro-7,7,8,8-tetracyanoquinodimethane, 2,5-difluoro-7,7,8,8-tetracyanoquinodimethane, tetrathiafur Ovalene-7,7,8,8, -tetracyanoquinodimethane mixture and the like.
These p-type dopants may be used alone or in combination of two or more.

Of these, metal halides are preferable, gold halides are more preferable, and gold trichloride (AuCl ₃ ) and chloroauric acid (HAuCl ₄ ) are even more preferable from the viewpoint of further increasing the conductivity of the conductive film. Gold trichloride (AuCl ₃ ) is particularly preferred.

<Method of contacting carbon nanotube-containing film with p-type dopant>
The method of bringing the CNT-containing film into contact with the p-type dopant is not particularly limited, but (1) a method of immersing the CNT-containing film in a p-type dopant-containing liquid obtained by dispersing or dissolving the p-type dopant in a medium, (2) A method of applying a p-type dopant-containing liquid on the CNT-containing film. After the immersion or application, the conductive film of the present invention can be formed by removing the medium from the p-type dopant-containing liquid attached to the CNT-containing film.
In the contact between the CNT-containing film and the p-type dopant, the CNT-containing film may be laminated on the base film or the peeling support, or may be a self-supporting film peeled from the peeling support. There may be.

  And as a method of making a CNT containing film and a p-type dopant contact, the method of (2) mentioned above is preferable. Hereinafter, the case of using the method (2) will be described as an example, and the contact method between the carbon nanotube-containing film and the p-type dopant will be described in detail.

The medium for dispersing or dissolving the p-type dopant is not particularly limited, and for example, those mentioned as the dispersion medium of the CNT dispersion liquid can be used. These may be used alone or in combination of two or more. Of these, ethanol is preferred.
A p-type dopant-containing liquid can be prepared by dispersing or dissolving the p-type dopant in these media by a known method.

  In addition, as a method of applying a p-type dopant-containing liquid on a CNT-containing film and a method of removing a medium from a p-type dopant-containing liquid applied on a CNT-containing film, As the method for applying the dispersion and the method for removing the dispersion medium from the CNT dispersion, those described above can be used. Although not particularly limited, the step of applying the p-type dopant-containing liquid on the CNT-containing film, the step of removing the medium from the p-type dopant-containing liquid applied on the CNT-containing film, and storage of the obtained conductive film are as follows: You may carry out in an inert gas or a vacuum. In some cases, deactivation of dopant species can be reduced by performing the reaction in an inert gas.

Here, the amount (doping amount) of doping the p-type dopant onto the CNT-containing film is not particularly limited, but is preferably 0.0001 mg / cm ² or more, more preferably 0.001 on a unit area basis of the CNT-containing film. 001mg / cm ² or more, more preferably 0.005 mg / cm ² or more, preferably 1 mg / cm ² or less, more preferably 0.5 mg / cm ² or less, even more preferably at 0.1 mg / cm ² or less . By setting the doping amount of the p-type dopant within the above range, the conductivity and reliability of the obtained conductive film can be further improved.

  In this way, by bringing the carbon nanotube-containing film into contact with the p-type dopant and removing the medium as necessary, the conductive film (conductive film) laminated on the base film, on the peeling support A laminated conductive film (conductive film with a support) or a conductive film that is a self-supporting film can be obtained.

  In the above method for producing a conductive film of the present invention, a CNT-containing film is prepared, and a desired conductive film is obtained by bringing the film into contact with a p-type dopant. Is added to obtain a p-type dopant-containing CNT dispersion, and a p-type dopant-containing CNT-containing film is formed according to the method (i) or (ii) described in [Method of forming carbon nanotube-containing film]. Thus, a conductive film made of the film can be obtained. Such a conductive film is also excellent in conductivity and reliability, like the conductive film of the present invention. The suitable aspect of the manufacturing method of this electrically conductive film is based on the manufacturing method of the electrically conductive film of this invention mentioned above, and the electrically conductive film obtained can be used similarly to the electrically conductive film of this invention.

(Conductive film)
One of the major features of the conductive film of the present invention is that it is manufactured using the above-described method for manufacturing a conductive film. The conductive film of the present invention has excellent conductivity and reliability.

(Conductive film)
Since the electroconductive film of this invention is equipped with the base film and the electrically conductive film mentioned above on the said base film, it has the outstanding electroconductivity and reliability. And as above-mentioned in the item of the manufacturing method of an electrically conductive film, a conductive film is formed on a base film by forming a CNT containing film on a base film, and making this CNT containing film contact with a p-type dopant. A laminated conductive film of the present invention can be obtained. Moreover, the electroconductive film of this invention can also be obtained by transferring the electrically conductive film on the peeling support body to a base film, or by sticking the electrically conductive film which is a self-supporting film to the base film. It can also be obtained.

The conductive film of the present invention has a surface resistivity of preferably 10 ⁴ Ω / □ or less, more preferably 5 × 10 ³ Ω / □ or less, particularly preferably 2 × 10 ³ Ω / □ or less, and the lower limit is Although not particularly limited, it is usually 0.01Ω / □ or more. In addition, in this invention, the surface resistivity of an electroconductive film can be measured by the method as described in the Example of this specification.

  And since the electrically conductive film of this invention and an electrically conductive film provided with this electrically conductive film have the outstanding electroconductivity and reliability, it is suitable for an antistatic film, electronic paper, a light control film, a touch panel, and a solar cell. It is preferably used for a solar cell electrode.

(Solar cell electrode and solar cell)
The electrode for solar cell of the present invention is obtained using the conductive film or conductive film of the present invention. Since the electrode for solar cell of the present invention uses the conductive film or conductive film of the present invention, the conversion efficiency is high and the durability is excellent.

  Here, examples of the solar cell include a silicon solar cell, a compound solar cell, and an organic solar cell. The solar cell electrode of the present invention is used as an electrode of these solar cells.

The solar cell electrode of the present invention will be described by taking a dye-sensitized solar cell, which is a kind of organic solar cell, as an example. A dye-sensitized solar cell usually has a structure in which a photoelectrode, an electrolyte layer, and a counter electrode are arranged in this order.
The photoelectrode is an electrode that can emit electrons to an external circuit by receiving light. The photoelectrode is usually a photoelectrode substrate in which a conductive film is formed on a base material, a porous semiconductor fine particle layer formed on the photoelectrode substrate, and a sensitizing dye on the surface of the porous semiconductor fine particle layer. And a sensitizing dye layer formed by adsorption.
The electrolyte layer is a layer for separating the photoelectrode and the counter electrode and efficiently performing charge transfer.
The counter electrode is an electrode for efficiently passing electrons entering from an external circuit to the electrolyte layer. The counter electrode usually has a counter electrode substrate in which a conductive film is formed on a base material and a catalyst layer formed on the counter electrode substrate.
The conductive film of the present invention is suitably used as, for example, the conductive film of the above-described photoelectrode substrate or counter electrode substrate, and the conductive film of the present invention is suitably used, for example, as the above-described photoelectrode substrate or counter electrode substrate. It is done.

And the solar cell of this invention is equipped with the electrode for solar cells of this invention mentioned above. The solar cell of this invention will not be specifically limited if it is provided with the electrode for solar cells of this invention. For example, depending on the type of semiconductor substrate, a crystalline silicon solar cell such as a single crystal silicon solar cell, a polycrystalline silicon solar cell, a microcrystalline silicon solar cell, or a multi-bonded silicon solar cell; an amorphous silicon solar cell; Examples include those classified into compound solar cells such as GaAs solar cells, CIS solar cells, and CdTe solar cells; organic solar cells such as dye-sensitized solar cells and organic thin film solar cells.
Moreover, the solar cell of this invention is not limited to what uses the sun as a light source, For example, you may use indoor illumination as a light source.
Since the solar cell of the present invention includes the solar cell electrode of the present invention, the conversion efficiency is high. Since such characteristics are particularly utilized, the solar cell of the present invention is preferably used as a portable solar cell or an indoor solar cell.

EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples.
In the examples and comparative examples, the surface resistivity was measured by the following method. The following method was used as a method for evaluating conductivity and reliability.
<Surface resistivity>
A resistivity meter (manufactured by Mitsubishi Chemical Analytech Co., Ltd., product name “Loresta (registered trademark) -GP MCP-T610”) was used, and the measurement was performed as described below in accordance with JIS K7194.
Specifically, the surface resistivity (sheet resistance) of the object was measured using a four-terminal method in an environment of a temperature of 25 ° C. and a humidity of 20% RH.
<Conductivity>
Surface resistivity of the laminate of the CNT-containing film and substrate film (pre-doping laminate) before doping (before contact with the dopant) and conductivity after doping (after contact with the dopant and after drying) The surface resistivity of the conductive film (conductive film after doping) was measured to evaluate the conductivity.
<Reliability>
The surface resistivity of the conductive film (conductive film after storage) after storing the conductive film after doping in an environment of temperature 25 ° C. and humidity 20% RH for 500 hours was measured to evaluate the reliability.

Example 1
<Synthesis of carbon nanotubes>
SGCNTs were obtained by the super-growth method according to the description in WO 2006/011655.
The obtained SGCNT had a BET specific surface area of 800 m ² / g, a mass density of 0.03 g / cm ³ , and a micropore volume of 0.44 mL / g. In addition, as a result of randomly measuring the diameter of 100 SGCNTs using a transmission electron microscope, the average diameter (Av) was 3.3 nm, and the sample standard deviation (σ) of the diameter was multiplied by 3 (3σ). Was 1.9 nm, (3σ / Av) was 0.58, and the average length was 100 μm. In addition, the obtained SGCNT was mainly composed of single-walled CNTs.
<Formation of carbon nanotube-containing film>
In a sample bottle with a capacity of 50 mL, 0.005 g of the above-mentioned carbon nanotube (SGCNT) and 0.005 g of sodium salt of carboxymethyl cellulose (CMC-Na; manufactured by Daicel Chemical Industries, Ltd., product name “CMC Daicel (product number 1130)”) as a dispersant And 10 g of pure water were added, followed by treatment with a bath-type ultrasonic disperser for 30 minutes to obtain a CNT dispersion (CNT concentration 0.05 mass%).
And said CNT dispersion liquid was apply | coated using the spray-coating method on PET film (Toyobo Co., Ltd. make, "Cosmo Shine (trademark)", product number A4100, with an easily bonding layer) as a base film. The CNT dispersion on the PET film was dried at 80 ° C. to form a CNT-containing film. The surface resistivity of the laminate (a laminate before doping) of the CNT-containing film and the PET film was measured.
<Preparation of ethanol solution of p-type dopant>
An ethanol solution (gold trichloride concentration of 0.02% by mass) of gold trichloride (AuCl ₃ ; manufactured by Wako Pure Chemical Industries) as a p-type dopant was prepared.
<Preparation of conductive film and conductive film>
Then, on the CNT-containing film formed on the PET film, the above-described gold trichloride (AuCl ₃ ) ethanol solution is cast using a casting method so that the doping amount of gold trichloride is 0.01 mg / cm ^2. And then dried at 80 ° C. to prepare a conductive film having a conductive film on a PET film. According to the above, the surface resistivity of the obtained conductive film (conductive film after doping) and the surface resistivity of the conductive film after storage were measured. The results are shown in Table 1.

(Example 2)
Laminate in the same manner as in Example 1 except that soda glass (“ASLAB slide glass” manufactured by ASONE, model number 10127101P, thickness: 1.0 to 1.2 mm) was used instead of PET film as the base film. The body, the electrically conductive film, and the electroconductive film were produced, and the surface resistivity was measured. The results are shown in Table 1.

(Example 3)
A laminate, a conductive film and a conductive film were produced in the same manner as in Example 2 except that CMC-Na was not used when forming the CNT-containing film, and the surface resistivity was measured. The results are shown in Table 1.

Example 4
A laminated body and a conductive film in the same manner as in Example 2 except that chloroauric acid tetrahydrate (HAuCl ₄ .4H ₂ O; manufactured by Wako Pure Chemical Industries, Ltd.) was used instead of gold trichloride as the p-type dopant. And the conductive film was produced and the surface resistivity was measured. The results are shown in Table 1.

(Example 5)
Example 2 with the exception that tetrafluorotetracyanoquinodimethane (F ₄ TCNQ; purity> 98.0% (sublimation product), manufactured by Tokyo Chemical Industry Co., Ltd.) was used as the p-type dopant instead of gold trichloride. Similarly, a laminate, a conductive film and a conductive film were prepared, and the surface resistivity was measured. The results are shown in Table 1.

(Example 6)
A laminate, a conductive film and a conductive film were prepared in the same manner as in Example 2 except that silver nitrate (AgNO ₃ ; manufactured by Wako Pure Chemical Industries, Ltd.) was used instead of gold trichloride as the p-type dopant. The rate was measured. The results are shown in Table 1.

(Comparative Example 1)
A laminate was produced in the same manner as in Example 2, and the surface resistivity was measured. Further, the p-type dopant was not brought into contact with the CNT-containing film, and the laminate was regarded as a conductive film, and the surface resistivity was measured in the same manner. The results are shown in Table 1.

(Comparative Example 2)
Example 2 was used except that cesium carbonate (Cs ₂ CO ₃ ; purity 99.999%, manufactured by Kojundo Chemical Laboratories), which is an n-type dopant, was used instead of the gold trichloride, which was a p-type dopant. Then, a laminate, a conductive film and a conductive film were prepared, and the surface resistivity was measured. The results are shown in Table 1.

(Comparative Example 3)
Instead of SGCNT, VGCF-H (average diameter (Av) = 150 nm; manufactured by Showa Denko), which is a multilayer and does not satisfy 0.60> 3σ / Av> 0.20, and a CNT-containing film A laminate, a conductive film, and a conductive film were produced in the same manner as in Example 2 except that CMC-Na was not used when forming the film. However, the surface resistivity was too high to be measured. could not.

  From Table 1, the conductive films obtained in Examples 1 to 6 have a lower surface resistivity than those of Comparative Example 1 that was not subjected to doping treatment and those of Comparative Example 2 using an n-type dopant. It can be seen that the film is excellent in conductivity and maintains a low surface resistivity even after storage, and is excellent in reliability. Moreover, from Examples 2-6, it turns out that the electroconductivity and reliability of an electroconductive film can be improved by changing the kind of p-type dopant. Furthermore, it can be seen from Examples 1 and 2 that the conductivity and reliability of the conductive film after doping can be improved by changing the type of the base film.

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 reliability can be provided.
ADVANTAGE OF THE INVENTION According to this invention, the electrically conductive film excellent in electroconductivity and reliability, the electroconductive film using the said electrically conductive film, the electrode for solar cells using the said electrically conductive film or the said electroconductive film, and a solar cell are provided. be able to.

Claims (8)

A step of contacting a film containing carbon nanotubes having an average diameter (Av) and a standard deviation (σ) of the diameter satisfying a relational expression: 0.60> 3σ / Av> 0.20 with a p-type dopant;
A method for producing a conductive film comprising:   The method for producing a conductive film according to claim 1, wherein the p-type dopant includes at least one of gold trichloride and chloroauric acid.   The manufacturing method of the electrically conductive film of Claim 1 or 2 whose average length of the said carbon nanotube is 0.1 micrometer or more and 10 mm or less.   The electrically conductive film manufactured by the manufacturing method of the electrically conductive film in any one of Claims 1-3. A base film, and a conductive film on the base film,
The electroconductive film whose said electrically conductive film is the electrically conductive film of Claim 4. The conductive film according to claim 5, wherein the surface resistivity is 0.01Ω / □ or more and 10 ⁴ Ω / □ or less.   The electrode for solar cells using the electrically conductive film of Claim 4, or the electroconductive film of Claim 5 or 6.   A solar cell provided with the electrode for solar cells of Claim 7.