JP2009301799A - Transparent conductive film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transparent conductive film which is not deteriorated by ultraviolet rays, and which is improved in conductivity by using carbon nanotubes. <P>SOLUTION: The transparent conductive film includes a substrate, a carbon nanotube layer with a mesh structure formed on the substrate, and a metal oxide layer formed on the carbon nanotube layer. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a transparent conductive film using carbon nanotubes.

  Indium tin oxide (ITO) is currently used as the transparent conductive film used for flat panel displays and touch panels, but there are concerns about the rise and depletion of indium, and alternative materials are being actively studied. .

  For example, as a transparent conductive film having performance equivalent to that of ITO, there is a conductive film using an organic material disclosed in Patent Document 1. In this example, a polythiophene material is used as a transparent conductive film material, and carbon nanotubes (CNT) are contained therein, thereby obtaining performance equivalent to that of ITO. Of these, the polythiophene material functions as a conductive material having the same conductivity and transparency as ITO, and the carbon nanotube functions as a material that reduces the contact resistance of the surface of the polythiophene film.

  However, the polythiophene of the above conventional example is deteriorated by ultraviolet rays, and there is a problem that conductivity is lowered (Patent Document 2). That is, since displays, touch panels, and the like are often used in an indoor / outdoor environment where ultraviolet rays exist, the transparent conductive film deteriorates and the image quality deteriorates, and the touch panel has poor contact.

  Patent Document 1 discloses that there is no difference in sheet resistance when carbon nanotubes are contained and when carbon nanotubes are not contained. Therefore, it can be seen that the carbon nanotubes do not contribute to the sheet resistance of the transparent conductive film. In the polythiophene film, there is no contact between the carbon nanotubes, so an electrical network is not formed, and it seems that each is in an isolated state. That is, the carbon nanotube having high conductivity is used for reducing the contact resistance on the surface of the transparent conductive film, and has not been used for reducing the sheet resistance.

Patent Document 3 discloses a transparent conductive film having a network structure using the conductivity of carbon nanotubes. However, further improvement in conductivity has been desired.
JP2008-50391 JP2007-70455 JP2007-138026

  In view of the above problems, the present invention aims to provide a highly reliable conductive film that does not deteriorate due to ultraviolet rays or the like, and to improve the conductivity by carbon nanotubes.

  It has a substrate, a net-like carbon nanotube layer formed on the substrate, and a metal oxide layer formed on the carbon nanotube layer.

  According to the above structure, since the metal oxide layer and the carbon nanotube layer are resistant to ultraviolet rays, the transparent conductive film does not deteriorate. Further, in the net-like carbon nanotube layer, the carbon nanotubes come into contact with each other to form an electrical network, so that a transparent conductive film utilizing the conductivity of the carbon nanotubes is obtained. As a result of repeated experiments, by forming a metal oxide layer on the network carbon nanotube layer, we have a transparent conductive film that has several times higher conductivity than the conductivity of only the network carbon nanotube layer For the first time in the world to be able to create. That is, according to the present invention, there is an effect that the performance of the transparent conductive film is dramatically improved and the sheet resistance can be reduced as compared with the conventional transparent conductive film.

The transparent conductive film of the present invention is characterized in that the metal oxide layer is made of zinc oxide.
Since zinc oxide has a higher transmittance than ITO, the transmittance of the transparent conductive film can be kept high. Moreover, although zinc oxide has a higher resistivity than ITO, since the conductivity of the carbon nanotube can be utilized, the resistivity of the entire transparent conductive film can be reduced. Zinc is richer in resources than indium and can provide a transparent conductive film at low cost.

  In the transparent conductive film of the present invention, the volume occupancy of the carbon nanotube layer is 1 to 50%.

  When the volume occupancy of the carbon nanotube layer is 1 to 50%, the sheet resistance is 10 kΩ / □ or less and the transmittance is 70% or more, which can be used for a touch panel.

  In the transparent conductive film of the present invention, the volume occupancy of the carbon nanotube layer is 1 to 10%.

  When the volume occupancy of the carbon nanotube layer is 1 to 10%, the sheet resistance is 10 kΩ / □ or less and the transmittance is 90% or more, which can be used for a flat panel display.

  According to the transparent conductive film of the present invention, since the metal oxide layer and the carbon nanotube layer are resistant to ultraviolet rays, the transparent conductive film is not deteriorated and the performance of the transparent conductive film can be greatly improved. .

  A preferred embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic sectional view of a transparent conductive film 4 of the present invention.

  In addition, this embodiment is an example and implementation with a various form is possible within the scope of the present invention.

<Transparent conductive film>
The transparent conductive film 4 of the present invention includes a substrate 1, a net-like carbon nanotube layer 2 formed on the substrate 1, and a metal oxide layer 3 formed on the carbon nanotube layer 2. Features.

<Board>
If the board | substrate 1 in this embodiment is a material generally used as a board | substrate of a touch panel or a flat panel display, the material will not be specifically limited. For example, a glass substrate such as soda glass, fused silica glass, or crystalline quartz glass, or a heat resistant resin plate made of a flexible film made of a material such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN) is used. Can do.

<Carbon nanotube layer>
The carbon nanotube layer 2 is made of carbon nanotubes (hereinafter also referred to as “CNT”). As the carbon nanotubes, there are single-walled carbon nanotubes, double-walled carbon nanotubes, and multi-walled carbon nanotubes. Any carbon nanotube can be used in the present invention, but a single-walled one is preferable because of its high conductivity, and a commercially available one having a diameter of several nm or less and a length of several μm can be used. .

  Carbon nanotubes are known to have metallic properties, semi-metallic properties, and semiconducting properties, depending on the arrangement of carbon atoms. In the transparent conductive film of the present invention, carbon nanotubes having any of these properties may be used, but among these, it is more preferable to use those having metallic properties.

A method for creating the carbon nanotube layer 2 will be described below.
First, a carbon nanotube is mixed with an aqueous solution in which catechin, a catechin derivative or a catechin polymer is dissolved in water, and a dispersion liquid in which the carbon nanotube is dispersed by ultrasonic waves is obtained. Since the catechin, the catechin derivative or the catechin polymer is adsorbed on the carbon nanotube, it can be sufficiently dispersed in water as a solvent.

  In the present invention, a primary pretreatment such as cutting the carbon nanotube or modifying the surface is unnecessary, and a dispersion can be easily obtained. In addition, as the catechin, catechin derivative or catechin polymer, commercially available green tea or the like can be used, and the cost can be greatly reduced. In addition, it is a dispersant that can be used safely with little concern about environmental pollution.

  Second, the dispersion is applied to the substrate 1. As a method of applying to the substrate 1, a predetermined amount of the dispersion liquid is dropped onto one surface of the substrate 1 using a pipette. Note that the same amount of the dispersion may be applied by spraying. As another method, a dip coating method in which the substrate is lifted after being immersed in the dispersion liquid may be used, but attention should be paid to the fact that it is applied to both surfaces of the substrate. As described above, since the dispersion to be applied is an aqueous solution of catechin, catechin derivative or catechin polymer, the substrate is a hydrophilic substrate or a substrate subjected to a hydrophilic surface treatment is used. There is a need. Thereby, it can apply | coat to the whole board | substrate uniformly. In addition to water, methanol and the like can be used as the solvent for catechin, but these are generally hydrophilic solvents and can be used similarly. If a substrate having a hydrophobic surface is used, uniform coating becomes difficult. Also, the dispersant is not limited to anything, and as described above, a dispersant containing catechin, a catechin derivative or a catechin polymer was effective for uniform coating. Note that SDS (sodium dodecyl sulfate), which is a well-known dispersant, was not effective for uniform coating.

  After coating, it is heated and dried on a hot plate. In addition, it may be exposed to a dry atmosphere or dried in a dryer. Thereby, it is possible to uniformly apply the carbon nanotube dispersion film on the substrate 1. Further, it is not necessary to cut carbon nanotubes having a length of several μm or more, and they can be used as they are and can be easily dispersed.

  Third, the dried coating film is washed with water and dried. Then, only the catechin, catechin derivative or catechin polymer having high affinity with water starts to dissolve in the water from the dispersion film, and the carbon nanotube film remains on the substrate 1. After washing and drying in the same manner as described above, a carbon nanotube film can be obtained. Thereby, the catechin, the catechin derivative or the catechin polymer can be removed, and only the carbon nanotube film can be formed on the substrate 1.

  When the sheet resistance of the carbon nanotube film obtained above is measured by the four probe method, it is 100 kΩ / □ or less, the average visible light transmittance in the wavelength range of 400 nm to 800 nm is 80% or more, and a good reticulated carbon nanotube Become a film. This is used as the net-like carbon nanotube layer 2 of the transparent conductive film of the present invention.

  When the concentration of the catechin, catechin derivative or catechin polymer in the aqueous solution is 100 mg / l to 1 g / l, the carbon nanotubes can be sufficiently dispersed in the aqueous solution.

  Further, when the concentration of the carbon nanotube in the aqueous solution is 1.5 mg / l to 15 mg / l, a uniform carbon nanotube film can be formed on the substrate.

  Furthermore, when the thickness of the carbon nanotube film is 2.7 to 50 nm, the sheet resistance is 10 kΩ or less, the average visible light transmittance in the wavelength range of 400 nm to 800 nm is 80% or more, and a good carbon nanotube layer 2 is formed. Obtainable.

<Metal oxide layer>
The metal oxide layer 3 in the present invention is formed on the carbon nanotube layer 2.

  It is preferable that the material of the metal oxide layer is a material that can generally be used for the transparent conductive film. Examples of such materials include indium tin oxide (ITO), tin oxide doped with fluorine (FTO), and zinc oxide (ZnO). The reason is that when a metal wiring material is provided on the surface of the transparent conductive film to supply power to the transparent conductive film, the resistance from the wiring material to the carbon nanotube layer 2 through the metal oxide layer 3 can be reduced. Because. A material other than the above may be used, but if the conductivity is low, the resistance from the wiring material to the carbon nanotube layer 2 tends to be high, so the metal oxide layer 3 needs to be further thinned, and is obtained in the present application. It is easy to reduce the effect of dramatically increasing the conductivity by forming a simple metal oxide layer 3 on the carbon nanotube layer 2.

A method for producing the metal oxide layer 3 will be described below.
A metal oxide layer 3 is formed on the carbon nanotube layer 2 by spraying.

  First, a zinc oxide raw material such as zinc acetate or zinc acetylacetonate is dissolved in an organic solvent such as methyl alcohol to prepare a coating solution for the metal oxide layer. In order to increase the conductivity of the metal oxide layer 3, aluminum can be doped by adding aluminum chloride as a doping material. In addition, indium chloride or the like can be added to dope indium.

  Next, the glass substrate 1 on which the reticulated carbon nanotube layer 2 is formed is heated on a hot plate. The coating solution for the metal oxide layer 3 is placed in a spray container and applied onto the heated substrate 1 while spraying. Then, the coating solution is heated and fired, and the metal oxide layer 3 can be formed on the reticulated carbon nanotube layer 2. Since the carbon nanotube layer 2 is network-like, voids may occur between the carbon nanotubes. At this time, the metal oxide layer 3 is formed both on the carbon nanotube layer 2 and on the glass substrate by penetrating the gap between the carbon nanotubes, and the entire surface of the substrate 1 is covered with the metal oxide layer 3. Even if the metal oxide layer 3 is not formed in the gap between the carbon nanotubes, the influence on the conductivity of the entire transparent conductive film is small.

  Thereby, the transparent conductive film 4 of this invention as shown in FIG. 1 is produced.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited thereto.

<Measurement and evaluation method>
About an Example and / or a comparative example, each measurement and evaluation were implemented with the following method about the following items.

(Calculation of carbon nanotube film thickness (CNT film thickness))
The sheet resistance of the carbon nanotube having a known film thickness was measured in advance, the relationship between the film thickness and the sheet resistance was determined, and the film thickness was converted from the measured resistance value of the sample.

First, a dispersion solution of SDS (sodium dodecyl sulfate: Sigma-Aldrich) dissolved in water is used. The concentration is 3.5 mmol / l. Carbon nanotube 0.3g was put into 100 ml of this dispersion solvent, and the dispersion process was performed for 10 minutes with the ultrasonic wave, and the carbon nanotube dispersion liquid was produced. When this is filtered on a Millipore filter and the solvent is removed, a carbon nanotube film is formed on the Millipore filter. SDS still remains in the carbon nanotube film. Next, pure water is dropped onto the carbon nanotube film on the filter and sucked in the same manner, so that the SDS is dissolved in pure water and washed to form a film of only carbon nanotubes from which SDS has been removed. This was dried to obtain a carbon nanotube film on the filter. The carbon nanotube film had a thickness of 6.3 μm and a sheet resistance of 4.3 Ω / □, which was 2.7 × 10 ⁻³ Ωcm in terms of resistivity.

  The thickness of the carbon nanotube film in Table 2 is calculated in inverse proportion to the sheet resistance because the thickness is 6.3 μm when the sheet resistance of the carbon nanotube is 4.3Ω / □.

(Visible light transmittance)
The measurement was performed using a visible ultraviolet spectrophotometer (JASCO V-550) manufactured by JASCO Corporation.

(Sheet resistance measurement method)
(1) a carbon nanotube film sheet in which only the carbon nanotube film is formed, (2) a transparent conductive film sheet in which the carbon nanotube film and the metal oxide film are formed, and (3) only the metal oxide film is formed on the substrate. The sheet resistance was measured for each of the plain film sheets.

For the measurement, a four-terminal measuring instrument Loresta-GP manufactured by Dia Instruments was used.
(Calculation of metal oxide film thickness)
The metal oxide film is formed by spraying and firing the raw material liquid. The film thickness is proportional to the number of sprays. Therefore, if the film thickness created by one spray is estimated in advance, the film thickness can be calculated from the number of sprays. Hereinafter, the film thickness produced by one spray is estimated.

  The first example is a case where the metal oxide is indium-doped zinc oxide. First, a plain film obtained by firing only indium-doped zinc oxide is prepared. Zinc acetylacetonate (manufactured by Sigma Aldrich) as a zinc oxide raw material and indium chloride (manufactured by Wako Pure Chemical Industries) as a dopant are dissolved in methanol (manufactured by Wako Pure Chemical Industries) as a solvent to obtain a coating solution for a zinc oxide film. It was. The total metal concentration in the solution is 250 mmol / l, and the atomic ratio of indium to the total metal concentration is 5%. This application solution is put into a spray container having a spray amount of 0.2 ml. The glass substrate was heated on a hot plate at 350 ° C., and intermittent spraying was performed 60 times every 10 seconds from above 15 cm. Next, when the film thickness of the produced zinc oxide film was measured, it was 87 nm. That is, it can be converted when a zinc oxide film of 1.5 nm is formed on a glass substrate per spray. From this point on, the thickness of the metal oxide film to be produced is the product of the number of sprays and 1.5 nm.

  The second example is aluminum-doped zinc oxide. Aluminum dopant (manufactured by Wako Pure Chemical Industries) was used as a dopant, and the total metal concentration in the solution was 83 mmol / l. Although the total metal concentration is different from the above example, the atomic ratio of aluminum to the total metal concentration is 5% as in the above example. Using this spray container, the solution was intermittently sprayed 150 times every 10 seconds toward a glass substrate heated to 350 ° C. It was 68 nm when the film thickness of the produced zinc oxide film | membrane was measured. That is, a zinc oxide film having a thickness of 0.45 nm is generated per spray. Accordingly, the film thickness is a product of the number of sprays and 0.45 nm.

(Calculation of carbon nanotube layer volume occupancy (CNT layer volume occupancy) in transparent conductive film)
A value obtained by dividing the film thickness of the carbon nanotube film by the sum of the film thickness of the carbon nanotube film and the film thickness of the metal oxide film was defined as the CNT layer volume occupation ratio.

(Sheet resistance reduction index)
The sheet resistance reduction index was determined by the following formula.

(Sheet resistance reduction index (B) / (A)) = (Sheet resistance index (B) after formation of metal oxide film) / (Sheet resistance index (A) when only a CNT film is formed)
That is, the smaller the value, the greater the reduction rate of the sheet resistance.

(Resistivity)
The resistivity of the transparent conductive film was determined by multiplying the sheet resistance value by the sum of the film thickness of the carbon nanotube film and the film thickness of the metal oxide film.

<Examples 1-7>
(Production of carbon nanotube layer)
First, a carbon nanotube dispersion was prepared.

  Carbon nanotubes were placed in an aqueous solution in which catechin was dissolved in water (manufactured by Suntory Ltd., trade name: Iemon Enome, tea catechin concentration 660 mg / l), and subjected to a dispersion treatment with ultrasound for 10 minutes. Table 2 shows the concentration of the produced carbon nanotube dispersion. From Examples 1 to 7, seven types of carbon nanotube concentrations of 1.5 to 15 mg / l were prepared.

This dispersion was pipetted onto a glass substrate (amount made by Corning, product name: 1737, substrate size: width 20 mm × length 40 mm × thickness 0.7 mm) in an amount of 25 to 75 μl / cm ² shown in Table 2. Water was evaporated on a hot plate that was uniformly hung and heated to 60 ° C., and dried.

  Seven types of obtained samples were immersed in pure water and washed to remove catechin molecules. Washing was repeated three times with pure water. After washing, it was naturally dried to form a carbon nanotube film from which catechin molecules were removed. The various measurements and evaluations described above were performed on the obtained carbon nanotube film. The results are shown in Table 2. Although the catechin molecules may remain slightly, the influence of the catechin molecules seems to be small because the sheet resistance value of the carbon nanotube film shown in Table 2 is not remarkably large.

(Production of metal oxide layer)
Next, a zinc oxide thin film was formed as a metal oxide layer on the network carbon nanotube layer. The first example of the metal oxide layer is indium-doped zinc oxide. Zinc acetylacetonate (manufactured by Sigma Aldrich) as a zinc oxide raw material and indium chloride (manufactured by Wako Pure Chemical Industries) as a dopant are dissolved in methanol (manufactured by Wako Pure Chemical Industries) as a solvent, and an indium-doped zinc oxide film coating solution It was. The second example is aluminum doped zinc oxide. Instead of the above-mentioned indium chloride, aluminum chloride (manufactured by Wako Pure Chemical Industries, Ltd.) was used to obtain a coating solution of aluminum-doped zinc oxide. Table 1 shows the concentrations of these coating solutions.

  The total metal concentration is the total concentration of zinc atoms and dopant atoms in the solution and is expressed in molar concentration. Note that the atomic ratio of the dopant to the total metal concentration is all 5%. This application solution is put into a spray container having a spray amount of 0.2 ml. While the glass substrate on which the reticulated carbon nanotube layer has been formed is placed on a hot plate at 350 ° C. and heated, the coating solution is sprayed intermittently from the top of 15 cm every 10 seconds. The number of sprays on each sample is as shown in Table 1. Then, the coating solution was baked on the substrate to form a zinc oxide film.

  The various measurements and evaluations described above were performed on the obtained transparent conductive film. The results are shown in Table 2.

<Comparative Examples 1-2>
(Production of metal oxide layer)
As a comparative example, a plain film was produced by firing only a metal oxide layer on a glass substrate. Since the manufacturing method is the same as that described in the section of the method for measuring the metal oxide film thickness, detailed description thereof is omitted. Two types of zinc oxide thin films with different dopants, total metal concentration, and number of sprays were prepared. Table 1 shows the dopant, total metal concentration, and number of sprays. With respect to the obtained plain films of Comparative Examples 1 and 2, the visible light transmittance and the resistivity were measured. The results are shown in Table 2.

  (Evaluation results)

  First, the evaluation results of the carbon nanotube film alone are shown in the left column of Table 2. The sheet resistances of the carbon nanotube films of Examples 1 to 7 were 520Ω / □ to 26 kΩ / □, and the average visible light transmittance in the wavelength range of 400 nm to 800 nm was 81% to 95%. When the thickness of the carbon nanotube film is 2.7 to 50 nm, the sheet resistance is 10 kΩ or less, the average visible light transmittance in the wavelength range of 400 nm to 800 nm is 80% or more, and the carbon nanotube has sufficient conductivity. A net-like carbon nanotube layer with high transmittance can be obtained while being pulled out.

  The evaluation results of the transparent conductive film in which a metal oxide layer is formed on these carbon nanotube films are shown in the right column of Table 2. The volume occupancy of the carbon nanotube layer (CNT layer volume occupancy) in the transparent conductive films of Examples 1 to 7 is 1.7 to 47%. Looking at the sheet resistance reduction index, it can be seen that the sheet resistance is reduced to 2/10 to 4/10 when zinc oxide is formed on the top as compared with the case where each sample has only carbon nanotubes. This is the first reduction effect we discovered as a result of repeated experiments and was obtained with good reproducibility. However, despite the fact that the reduction effect can be reliably obtained, the reason why the reduction can be reduced is not yet known.

Further, the visible light transmittance was 77% to 94%, which was a good value as a transparent conductive film. In particular, the visible light transmittances of Examples 4 to 7 were very good at 90% or more. FIG. 2 shows data on the wavelength dependence of the visible light transmittance of each material. FIG. 3 shows an example of an SEM image of a transparent conductive film produced by using the method of the present invention. Traces of reticulated carbon nanotubes can be observed. 4 shows a photograph of the transparent conductive film substrate of Example 2, and FIG. 5 shows a photograph of the transparent conductive film substrate of Example 7. In Example 2 of FIG. 4, since the transmittance is 78%, the coated region of the carbon nanotube can be visually observed. In Example 7 of FIG. 5, since the transmittance is 93%, the coating region of the carbon nanotube cannot be visually confirmed. That is, a sheet resistance value as low as 2.2 × 10 ³ Ω / □ can be maintained despite the thin carbon nanotube layer capable of increasing the transmittance.

  In this example, zinc oxide was used as the material for the metal oxide layer as described above. Zinc oxide has a disadvantage that the resistivity is generally higher than that of ITO, but the resistivity can be reduced by supplementing the conductivity by utilizing carbon nanotubes. However, zinc oxide has the advantage that the transmittance is higher than that of ITO, and the transmittance of the transparent conductive film can be maintained high. That is, by combining carbon nanotubes and zinc oxide, a transparent conductive film having low resistivity and high transmittance could be realized. Note that zinc used for zinc oxide has more resources than indium used for ITO, and can provide a transparent conductive film at low cost.

  Further, as shown in Table 2, the transparent conductive film of this example has a sheet resistance of 10 kΩ / □ or less and a transmittance of 70% or more, and thus can be sufficiently used for a touch panel. A sample having a transmittance of 90% or more can be used for a flat panel display that requires higher performance.

  In Comparative Examples 1 and 2, a transmittance of 87 to 96% was obtained, but the resistivity was about one to two digits higher than that of the example of the present invention. That is, although the transmittance | permeability of the Example of this invention was equivalent compared with the comparative example, the resistivity could be reduced about 1 to 2 digits, and the effect of the net-like carbon nanotube layer was able to be confirmed. .

  Eventually, even if the resistivity of zinc oxide is higher than that of ITO, a transparent conductive film having both transmittance and resistivity can be obtained by utilizing the high transmittance of zinc oxide while supplementing the conductivity with carbon nanotubes. . Note that Comparative Example 1 using indium chloride as a dopant has a feature that the resistivity can be reduced although the transmittance of the zinc oxide film is lower than that of Comparative Example 2 using aluminum chloride.

  As described above, according to the transparent conductive film of the present invention, the zinc oxide and carbon nanotube layers, which are metal oxide layers, are resistant to ultraviolet rays, so that the transparent conductive film does not deteriorate. Further, in the net-like carbon nanotube layer, the carbon nanotubes come into contact with each other to form an electrical network, so that a transparent conductive film utilizing the conductivity of the carbon nanotubes is obtained. Furthermore, as a result of repeated experiments, by forming a metal oxide layer on the network carbon nanotube layer, we have a transparent conductivity that is several times higher than the conductivity of only the network carbon nanotube layer. I discovered for the first time that I could create a membrane. That is, according to the present invention, there is an effect that the performance of the transparent conductive film is dramatically improved and the sheet resistance can be reduced as compared with the conventional transparent conductive film.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a schematic diagram of the transparent conductive film of this invention. It is data which shows the wavelength dependence of the transmittance | permeability of the transparent conductive film of this invention. It is an electron micrograph of the transparent conductive film of this invention. It is a photograph of the board | substrate in which the transparent conductive film of this invention was formed. It is a photograph of the board | substrate in which the transparent conductive film of this invention was formed.

Explanation of symbols

  1 substrate, 2 carbon nanotube layer, 3 metal oxide layer.

Claims (4)

  A transparent conductive film comprising a substrate, a net-like carbon nanotube layer formed on the substrate, and a metal oxide layer formed on the carbon nanotube layer.   The transparent conductive film according to claim 1, wherein the metal oxide layer is made of zinc oxide.   3. The transparent conductive film according to claim 1, wherein the volume ratio of the carbon nanotube layer is 1 to 50%.   3. The transparent conductive film according to claim 1, wherein the volume occupancy of the carbon nanotube layer is 1 to 10%.