This is a continuation of pending International Patent Application PCT/KR2011/009444 filed on Dec. 8, 2011, which designates the United States and claims the priority benefit of Korean Patent Application No. 10-2011-0101907 filed on Oct. 6, 2011, the entire contents of which are incorporated herein by reference.
The present invention relates to a one-dimensional conductive nanomaterial-based conductive film having conductivity thereof enhanced by a two-dimensional nanomaterial. More particularly, the present invention relates to a one-dimensional conductive nanomaterial-based conductive film, wherein the conductivity thereof is enhanced by laminating a two-dimensional nanomaterial, such as graphene or the like, on the upper surface of a film composed of a one-dimensional conductive nanomaterial such as carbon nanotubes, metal nanowires or the like.
Generally, a transparent conductive film is used in plasma display panels (PDPs), liquid crystal displays (LCDs), light-emitting diodes (LEDs), organic light-emitting diodes (OLEDs), touch panels, solar cells, and the like.
Such a transparent conductive film is used as electrodes of solar cells, liquid crystal displays, plasma display panels, smart windows and various light-receiving and light-emitting devices, and is used as antistatic films for automobile window glass or building window glass, transparent electromagnetic wave shielding films, heat reflection films, transparent heating elements for refrigerating showcases, and the like, because this transparent conductive film has high conductivity (for example, surface resistance: 1×103 Ω/sq or less) and high visible light transmission.
As a transparent conductive film, a tin oxide (SnO2) film doped with antimony or fluorine, a zinc oxide (ZnO) film doped with aluminum or potassium, an indium oxide (In2O3) film doped with tin, and the like are widely used.
Particularly, an indium oxide film doped with tin, that is, an In2O3—Sn film, is referred to as an indium tin oxide (ITO) film, and is generally used because it has low resistance. The ITO film is advantageous in that it has excellent physical properties, and, to date, it has frequently been introduced in processes, but is problematic in that the supply and demand of indium oxide (In2O3) is unstable because indium oxide (In2O3) is produced as a by-product from a zinc (Zn) mine or the like. Further, the ITO film is problematic in that it cannot be used for a flexible substrate, such as a polymer substrate or the like, because it does not have flexibility, and in that its production cost is high because it must be prepared at high-temperature and high-pressure conditions.
Meanwhile, in order to obtain a flexible display, a flexible conductive film prepared by coating a polymer substrate with a conductive polymer may be used. However, such a flexible conductive film is problematic in that its electrical conductivity is deteriorated when it is exposed to an external environment, and it is not transparent, thus restricting the use thereof.
In order to solve the above problems, technologies of coating various kinds of substrates with carbon nanotubes have recently been researched. Carbon nanotubes are advantageous in that they have electrical conductivity next to that of metal because they have a low electrical resistance of 10−4 Ωcm, their surface area is 1000 times or more larger than that of a bulk material, and their length is several thousands of times longer than their outer diameter, and thus they are ideal materials in terms of conductivity realization, and in that the bonding force thereof to a substrate can be improved by surface functionalization. Particularly, since carbon nanotubes can be used for a flexible substrate, it expected that the use thereof will be infinite.
As a conventional carbon nanotube-using technology, there is “a carbon nanotube-containing coating film” (Korean Application Publication No. 10-2004-0030553). This conventional technology is problematic in that only carbon nanotubes having an outer diameter of 3.5 nm can be used in consideration of dispersibility and electrical conductivity, and thus the usage thereof is restricted, and in that the dispersibility and adhesivity of carbon nanotubes are deteriorated at the time of forming a coating film, and thus the characteristics of the coating film are deteriorated with the passage of time.
As another conventional technology, Korean Patent Registration No. 10-869163 discloses “a method of manufacturing a transparent conductive film containing carbon nanotubes and a binder, and a transparent conductive film manufactured thereby”.
This conventional technology is configured such that acid-treated carbon nanotubes having an outer diameter of less than 15 nm are mixed with a binder (Here, the binder is added in an amount of 15 to 80 parts by weight, based on 100 parts by weight of the mixture) to obtain a carbon nanotube-binder mixed coating solution, and then the mixed coating solution is applied onto a substrate, thereby forming a transparent conductive film.
This conventional technology is also problematic in that the packing density of a carbon nanotube network is not high, so junction resistance increases, thereby decreasing conductivity, and in that carbon nanotubes have hydrophobicity, and thus it is difficult to apply a hydrophilic material onto carbon nanotubes.
Further, this conventional technology is problematic in that carbon nanotubes have pores on the surface thereof, so the surface thereof becomes rough, and thus there is a limitation in using carbon nanotubes as photoelectric elements.
Accordingly, the present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a one-dimensional conductive nanomaterial-based conductive film, wherein the conductivity thereof is enhanced by laminating a two-dimensional nanomaterial, such as graphene or the like, on the upper surface of a film composed of a one-dimensional conductive nanomaterial such as carbon nanotubes, metal nanowires or the like.
In order to accomplish the above object, an aspect of the present invention provides a one-dimensional conductive nanomaterial-based conductive film, the conductivity of which is enhanced by a two-dimensional nanomaterial, including: a substrate; a one-dimensional conductive nanomaterial layer formed on the substrate; and a two-dimensional nanomaterial layer formed on the one-dimensional conductive nanomaterial layer, wherein the one-dimensional conductive nanomaterial layer is formed of at least one one-dimensional conductive nanomaterial selected from among carbon nanotubes, metal nanowires and metal nanorods, and the two-dimensional nanomaterial layer is formed of at least one two-dimensional nanomaterial selected from among graphene, boron nitride, tungsten oxide (WO3), molybdenum sulfide (MoS2), molybdenum telluride (MoTe2), niobium diselenide (NbSe2), tantalum diselenide (TaSe2) and manganese oxide (MnO2).
Here, the substrate may be made of any one selected from the group consisting of glass, quartz, a glass wafer, a silicon wafer, and plastic.
The one-dimensional conductive nanomaterial layer may be formed by dispersing a one-dimensional conductive material in a solvent to obtain a one-dimensional conductive material solution and then applying the solution onto the substrate. The application of the solution may be performed using one method selected from among spraying, dipping, spin coating, screen printing, inkjet printing, pad printing, knife coating, kiss coating, and gravure coating.
The two-dimensional nanomaterial may be graphene oxide. The two-dimensional nanomaterial layer may be formed by acid-treating pure graphite to obtain graphite oxide, stripping the graphite oxide to form graphene oxide and then applying the graphene oxide onto the one-dimensional conductive nanomaterial layer. Here, as the acid treatment, Staudenmaier method (L. Staudenmaier, Ber. Dtsch. Chem. Ges., 31, 1481-1499, 1898), Hummers method (W. Hummers et al 1, J. Am. Chem. Soc., 80, 1339, 1958), Brodie method (B. C. Brodie, Ann. Chim. Phys., 59, 466-472, 1860) and other modified methods for effectively oxidizing and stripping graphite are known. In the present invention, these methods are used.
The application of the graphene oxide may be performed using one method selected from among spraying, dipping, spin coating, screen printing, inkjet printing, pad printing, knife coating, kiss coating, gravure coating, and offset coating.
Accordingly, there is an advantage of enhancing the conductivity of a one-dimensional conductive nanomaterial film by laminating a two-dimensional nanomaterial, such as graphene or the like, on the upper surface of a film composed of a one-dimensional conductive nanomaterial such as carbon nanotubes, metal nanowires, metal nanorods or the like.
According to the present invention, there is an effect of enhancing the conductivity of a one-dimensional conductive nanomaterial film by laminating a two-dimensional nanomaterial, such as graphene or the like, on the upper surface of a film composed of a one-dimensional conductive nanomaterial such as carbon nanotubes, metal nanowires, metal nanorods or the like.
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
First, a one-dimensional conductive nanomaterial layer will be described.
The one-dimensional conductive nanomaterial layer is formed on a plastic substrate using a one-dimensional conductive nanomaterial. In this embodiment, as the substrate, a polyethylene terephthalate substrate is used. Further, as the one-dimensional conductive nanomaterial, carbon nanotubes, metal nanowires, metal nanorods or the like may be used, but, in this embodiment, carbon nanotubes are used.
First, 1 mg of single-wall carbon nanotubes are added to 100 mL of a surfactant solution (concentration: 1%), the carbon nanotubes are dispersed for 1 hour using a sonicator, and then the surfactant solution dispersed with carbon nanotubes is treated by a centrifugal separator at a rotation speed of 100 rpm for 30 min to separate upper-layer liquid, thereby preparing a carbon nanotube solution.
Subsequently, the prepared carbon nanotube solution is applied onto a polyethylene terephthalate substrate using a spray coater.
Through this procedure, the substrate is formed thereon with a carbon nanotube transparent conductive film, which is a one-dimensional conductive nanomaterial layer. In this case, a surfactant remains on the transparent conductive film. Therefore, when the surfactant is removed using distilled water, finally, a carbon nanotube transparent conductive film is formed as shown in
Subsequently, a two-dimensional nanomaterial layer is formed on the one-dimensional conductive nanomaterial layer.
Graphene oxide is prepared by stripping graphite oxide using a sonicator, wherein the graphite oxide is prepared by treating pure graphite with sulfuric acid and KMnO4 for 1 day and then purifying the treated graphite with hydrogen peroxide and hydrochloric acid.
The prepared graphene oxide is a single layer as shown in
The prepared oxide graphene is applied onto a carbon nanotube transparent conductive film, which is a one-dimensional nanomaterial layer, using a spray coater, thus forming a one-dimensional conductive nanomaterial-based conductive film, the conductivity thereof being enhanced by a two-dimensional nanomaterial.
As shown in
Next, in order to observe the water contact angle of a carbon nanotube transparent conductive film according to the application of graphene oxide,
From
Further, as shown in
As shown in
Such a phenomenon is based on the fact that, as shown in
Additionally explaining the fact, when the prepared carbon nanotube transparent conductive film is coated with graphene oxide using a spray coater, as shown in
As shown in
In second embodiment of the present invention, a carbon nanotube transparent conductive film was formed in the same manner as in first embodiment, except that boron nitride was used as a two-dimensional nanomaterial.
Boron nitride, similarly to graphite, is structured such that two-dimensional boron nitride layers are piled in layers.
In this embodiment, boron nitride was dispersed in an organic solvent such as alcohol or the like, and then treated with a sonicator and a homogenizer to prepare a two-dimensional boron nitride coating solution, and then the two-dimensional boron nitride coating solution is formed into a boron nitride sheet.
The prepared boron nitride coating solution was applied onto a carbon nanotube transparent conductive film to form a two-dimensional nanomaterial layer. Similarly to the carbon nanotube transparent conductive film coated with graphene oxide in the first embodiment, the surface resistance of the nanotube transparent conductive film coated with boron nitride was lowered.
The present invention relates to a one-dimensional conductive nanomaterial-based conductive film having conductivity thereof enhanced by a two-dimensional nanomaterial. More particularly, the present invention relates to a one-dimensional conductive nanomaterial-based conductive film, the conductivity of which is enhanced by laminating a two-dimensional nanomaterial, such as graphene or the like, on the upper surface of a film composed of a one-dimensional conductive nanomaterial such as carbon nanotubes, metal nanowires or the like. This conductive film can be industrially applicable.
Number | Date | Country | Kind |
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10-2011-0101907 | Oct 2011 | KR | national |
Number | Date | Country | |
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Parent | PCT/KR2011/009444 | Dec 2011 | US |
Child | 14243053 | US |