KR101598565B1 - A transparent carbon nanotube electrode and preparation method thereof - Google Patents

Abstract

Disclosed is a carbon nanotube (CNT) transparent electrode having excellent adhesion and a method of manufacturing the same. According to an embodiment of the present invention, a carbon nanotube thin film coated with a solution in which a carbon nanotube is mixed with a solvent is coated on a substrate, and a carbon nanotube thin film including an adhesive film coated with a solution in which an adhesive solution and a carbon nanotube dispersion solution are mixed. A transparent electrode is provided. Thereby, it is possible to provide a carbon nanotube transparent electrode having characteristics of a transparent electrode and excellent in adhesion.

Carbon nanotubes, CNTs, adhesives, styrene butadiene

Description

Technical Field [0001] The present invention relates to a transparent carbon nanotube electrode and a preparation method thereof,

The present invention relates to a carbon nanotube transparent electrode and a manufacturing method thereof.

A transparent electrode is required for a display device, and indium tin oxide (ITO) is used as a transparent electrode for a display. ITO is currently the most widely used material and features relatively high transparency and low sheet resistance. However, since the ITO thin film is formed by a physical vapor deposition (PVD) method such as sputtering or E-beam evaporation, the cost of forming the ITO thin film is high, There is a problem in that the price is increased according to In addition, when the ITO thin film is bent, a crack is generated and the resistance is increased, so that it is difficult to apply to a flexible device.

Recently, carbon nanotubes (hereinafter referred to as CNTs) have been attracting attention as a transparent electrode material that replaces ITO. CNT has excellent electrical conductivity and strength and can easily bend. Transparent electrodes can be used for LCD, OLED, touch screen panel (TSP) and paper like display The present invention can be widely applied not only to the same display device but also as an electrode material for an energy device such as a solar cell and a secondary cell.

The present invention relates to a transparent electrode using CNTs and a method of manufacturing the same, and in particular, to improve the adhesion of a CNT transparent electrode to a substrate using an adhesive.

The present invention further provides a CNT transparent electrode having excellent light transmittance, low sheet resistance, and excellent adhesive strength by further applying a solution obtained by mixing an adhesive and CNT to a substrate coated with a CNT dispersion solution.

According to an aspect of the present invention, there is provided a CNT transparent electrode,

A CNT thin film on which a CNT dispersion solution in which carbon nanotubes (CNTs) are dispersed in an organic solvent is coated on a substrate, and an adhesive film on which a solution in which an adhesive solution and a CNT dispersion solution are mixed is applied.

The CNT transparent electrode is characterized in that the adhesive solution is a mixed solution of an adhesive and a solvent.

The adhesive may be a polyimide resin, an acrylic resin, a polyurethane resin, an ethercellulose, an epoxy resin, a polyvinyl chloride solvent (PVC) A silicon-based adhesive, a silicone-based adhesive, a styrene-butadiene rubber, or a derivative thereof.

The CNT transparent electrode is characterized in that the mixing ratio of the adhesive and the solvent is 1:10 to 1:30.

The CNT transparent electrode is characterized in that the mixing ratio of the solution in which the adhesive solution and the CNT dispersion solution are mixed is 1:20 to 1:30.

Further, there is provided a CNT transparent electrode characterized in that a plurality of adhesive films are formed by applying a solution obtained by mixing the adhesive solution and the CNT dispersion solution.

In addition, a CNT transparent electrode characterized in that the substrate is flexible is provided.

According to another embodiment of the present invention, there is provided a method of manufacturing a CNT thin film, comprising: forming a CNT thin film by applying a CNT dispersion solution in which a carbon nanotube (CNT) is dispersed in a solvent; And ii) applying a solution prepared by mixing the CNT dispersion solution and an adhesive solution onto a substrate to form an adhesive film.

Further, a method of manufacturing a CNT transparent electrode further comprising a heat treatment step is provided.

The thin film may be formed by any one of a slit coating method, a spin coating method, a spray coating method, a filtration method, and a bar coating method.

According to an embodiment of the present invention, A CNT thin film coated with a solution of a carbon nanotube (CNT) in a solvent; And a CNT transparent electrode comprising an adhesive film coated with a solution obtained by mixing an adhesive solution and a CNT dispersion solution. Thus, it is possible to provide a CNT transparent electrode having excellent adhesion while maintaining the characteristics of the transparent electrode.

Hereinafter, the present invention will be described in detail. It should be understood, however, that the invention is not limited to the following examples, and that various forms of embodiments may be practiced within the scope of the appended claims, To facilitate the invention of the invention to those of ordinary skill in the art.

Preparation of CNT dispersion solution and adhesive solution

i) Step:

A substrate, carbon nanotube (CNT), organic solvent, and adhesive are prepared. The material used in the present invention is not particularly limited so long as it does not hinder the object of the present invention, and a commercially available product can be purchased and used. Here, the adhesive may be a polyimide, an acrylic resin, a polyurethane resin, an ethercellulose, an epoxy resin, a polyvinyl chloride solvent type, PVC, silicone-based adhesives, styrene-butadiene rubber, and the like. Examples of transparent materials for use in the transparent electrode include polyimide, epoxy resin, styrene-butadiene rubber and the like. In one embodiment of the present invention, styrene-butadiene rubber Styrene-butadiene rubber was used.

ii) Step:

In order to manufacture a CNT transparent electrode having excellent adhesion according to an embodiment of the present invention, a CNT dispersion solution and an adhesive solution should be prepared first. Here, the CNT dispersion solution is defined as a solution in which CNT is mixed with the first solvent at a predetermined ratio, and the adhesive solution is defined as a solution in which the adhesive is mixed with the second solvent at a predetermined ratio. In this embodiment, a benzene solution was used as a first solvent, a styrene butadiene rubber resin was used as an adhesive, and cyclohexanone, which is one of aliphatic cyclic ketones, was used as a second solvent. The styrene-butadiene rubber resin may be a styrene butadiene rubber (SBR), styrene butadiene styrene (SBS), or a styrene isoprene styrene (SIS) adhesive or a copolymer of styrene and butadiene.

Calculating the optimum ratio of CNT dispersion solution and adhesive solution

In the case of the CNT dispersion solution, the higher the density of CNT in benzene, the more transparent electrode can be formed with a smaller amount of CNT dispersion solution. However, when the density of CNT is high, , It is difficult to form a uniform film upon application. In this experiment, the density of CNT contained in benzene was 0.05 ~ 1 mg / l. In this case, the dispersibility could be secured while maintaining the characteristics of the transparent electrode.

Thereafter, an experiment was conducted to calculate the optimum ratio of the adhesive solution. Hereinafter, the ratio of the styrene-butadiene rubber resin as the solute of the adhesive solution to the cyclohexanone solvent as the solvent was set to 1:10 or less (Experimental Example 1), 1:10 to 1:30 (Experimental Example 2) , An experiment was conducted in which an adhesive solution was applied to a substrate by a spray method. Here, a spray method is used as a solution application method, but a conventionally known slit coating, spin coating, spray coating, or filtration method may be used. The respective coating methods are well known and detailed descriptions are omitted.

(Experimental Example 1)

Styrene-butadiene rubber resin: When the cyclohexanone ratio is less than 1:10, the amount of the solute is excessively increased and the viscosity of the solution is increased. Therefore, the thin film formed at the time of coating the substrate has an island- And includes an application area (uncoating).

The faulty island will be described with reference to Fig. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an illustration of an island failure that occurs upon application of an adhesive solution in accordance with an embodiment of the present invention. FIG. Referring to FIG. 1, an overcoated region 100 and an uncoated region 110 are shown on a substrate. The island defect means that when the amount of the solute in the adhesive solution is excessively large relative to the solvent, the viscosity of the solution increases and a uniform thin film is not formed, and the island-shaped over-coating region 100 and the non- Is bad. In this experiment, when the ratio of cyclohexanone as a solvent to the styrene-butadiene rubber resin as a solute was less than 1:10, defective islands as shown in Fig. 1 occurred.

(Experimental Example 2 and Experimental Example 3)

Styrene-butadiene rubber resin: When the ratio of cyclohexanone is increased to 1:10 or more, the viscosity of the solution gradually decreases and the coating is uniformly applied to the substrate. Then, the adhesion of the thin film decreases from the ratio of 1:30, The floating phenomenon occurs and the thin film is separated from the substrate and the resistance of the film is increased.

Therefore, the optimal ratio of the styrene-butadiene rubber resin, which is a solute, and cyclohexanone, which is a solvent, was calculated from 1:10 to 1:30 through the experiment of applying the above-mentioned adhesive solution.

Calculate optimum ratio of adhesive solution and CNT solution

Hereinafter, an experiment was conducted to calculate the optimum ratio of the adhesive solution and the CNT dispersion solution in terms of sheet resistance and transmittance for use as a transparent conductive film.

The CNT dispersion solution used here is determined within such a range as not to dissolve the solute in the solvent. In this experiment, a benzene solution diluted with CNT at a concentration of 0.1 mg / ml was used as the CNT dispersion solution, and a mixture of styrene butadiene rubber resin and cyclohexanone at a ratio of 1:10 was used as the adhesive solution.

The optimum ratio of the adhesive solution and the CNT dispersion solution will now be described with reference to the graph of FIG.

2 is a graph showing changes in sheet resistance and transmittance according to the ratio of the adhesive solution and the CNT dispersion solution according to an embodiment of the present invention.

As shown in FIG. 2, the permeability and sheet resistance tend to decrease as the ratio of the adhesive solution to the CNT dispersion solution increases. For use as a transparent electrode, a high transmittance and a low sheet resistance are required. Therefore, it is necessary to calculate an optimum ratio having a high transmittance and a low sheet resistance, even though the adhesive property is excellent.

Referring to the experimental results of FIG. 2, it can be seen that the sheet resistance is 340 Ω / sq and the transmittance is 80% when the ratio of the adhesive solution to the CNT dispersion solution is 5%. When the electrode is used as the electrode, the electrode characteristics are better as the sheet resistance is lower. However, when the transmittance is 80% or less, it is difficult to use the electrode as a transparent electrode. Therefore, the ratio of the adhesive solution to the CNT dispersion solution is about 5%.

Manufacture of carbon nanotube transparent electrode

A method of manufacturing a CNT transparent electrode having excellent adhesion according to an embodiment of the present invention will be described.

3 is a flowchart illustrating a method of manufacturing a CNT transparent electrode according to a first embodiment of the present invention.

Referring to FIG. 3, a substrate is prepared in step S300, and a CNT dispersion solution is coated on the substrate prepared in step S310. Here, the CNT dispersion solution is a solution in which CNT is mixed with an organic solvent at a predetermined ratio.

In step S320, a mixed solution prepared by mixing the adhesive solution and the CNT dispersion solution is applied on the substrate coated with the CNT dispersion solution. Here, the adhesive solution is a solution obtained by mixing a certain amount of an adhesive with an organic solvent, and the adhesive may be a styrene-butadiene rubber synthetic resin or an adhesive having a basic structure of a copolymer of styrene and butadiene, and the styrene- (Styrene Butadiene Styrene), SIS (Styrene Isoprene Styrene), or the like. In addition, the adhesive solution may be manufactured so as to be patternable including a photo-acrylic component.

Thereafter, in step S330, the substrate coated with the mixed solution of the CNT dispersion solution and the adhesive solution is heat-treated at a predetermined temperature and time.

This makes it possible to manufacture a CNT transparent electrode having a low sheet resistance and an excellent transmittance while having improved adhesion.

3, the manufacturing method of the substrate structure of the first embodiment of the present invention has been described. However, the number of times of application of the CNT dispersion solution and the application order may be changed according to the substrate structures of the second and third embodiments.

Hereinafter, the results of the embodiments will be described with reference to Figs. 4 to 6. Fig.

In order to obtain optimum coating conditions, the following experiment was carried out by adjusting the ratio of the adhesive solution. In this experiment, a styrene butadiene rubber synthetic resin and a mixed solution of cyclohexanone were used as an adhesive solution.

(Experimental Example 1)

a) 20 ml of a CNT dispersion solution having a density of 0.1 mg / ml (amount of CNT / volume of benzene) is applied by a spraying method or a spin coating method. In this case, the characteristics were measured with a transmittance of 80% and a resistance of 340? / Sq.

b) Apply 1 ml of a 1: 20 dilution of the adhesive solution (styrene butadiene: cyclohexanone = 1: 10) and CNT dispersion solution (0.1 mg / ml) by spraying or spin coating.

c) Thereafter, heat treatment is performed at 100 ° C.

In the case of Experimental Example 1, the substrate structure shown in FIG. 4 was produced. In this case, after applying a solution prepared by mixing the adhesive solution and the CNT dispersion solution, the final characteristic value was 80% of the transmittance and 340Ω / Did not occur. Also, no change in resistance or change in transmittance occurred after direct cleaning (DI cleaning).

(Experimental Example 2)

a) 20 ml of a CNT dispersion solution having a density of 0.1 mg / ml (amount of CNT / volume of benzene) is applied by a spraying method or a spin coating method. In this case, the characteristics were measured with a transmittance of 80% and a resistance of 340? / Sq.

b) 1 ml of a 1: 20 mixture of an adhesive solution (styrene butadiene: cyclohexanone = 1: 10) and a CNT dispersion solution (0.1 mg / ml) is applied by spraying or spin coating.

c) Thereafter, heat treatment is performed at 100 ° C. This step may be omitted as an intermediate heat treatment step.

d) Repeat 5 ml of the CNT dispersion solution with a density of 0.1 mg / ml (CNT quantity / volume of benzene) by spraying or spin coating. In this case, the characteristic was maintained at a transmittance of 80% and a resistance of 340? / Sq.

e) Thereafter, heat treatment is performed at 100 ° C.

In the case of Experimental Example 2, the substrate structure shown in FIG. 5 was produced, and the transmittance and resistance characteristics were similar in comparison with Experimental Example 1. FIG. However, when the intermediate annealing step c) is carried out, the upper CNT thin film is peeled off during direct cleaning, deteriorating the properties, and when the CNT thin film is not heat treated, the island shape defect occurs when the CNT dispersion solution is applied, . ≪ / RTI >

(Experimental Example 3)

a) 1 ml of a 1: 20 mixture of an adhesive (styrene butadiene: cyclohexanone = 1: 10) and a CNT dispersion solution (0.1 mg / ml) is applied by spraying or spin coating.

b) Thereafter, 20 ml of a CNT dispersion solution having a density of 0.1 mg / ml (volume of CNT / volume of benzene) is applied by a spraying method or a spin coating method. In this case, the characteristics were measured with a transmittance of 80% and a resistance of 340? / Sq.

c) After that, heat treatment is performed at 100 ° C.

In the case of Experimental Example 3, the substrate structure shown in FIG. 6 is generated, and when the upper CNT dispersion solution is applied, island shape defects are generated, which is disadvantageous in terms of uniformity.

Through the above-mentioned three experimental examples, it can be confirmed that even when a solution containing a mixture of an adhesive solution and a CNT dispersion solution is applied in manufacturing a carbon nanotube transparent electrode, the same characteristics are exhibited in terms of sheet resistance and transmittance.

As a result, a CNT transparent electrode having a sheet resistance of at least about 80% and a sheet resistance of about 340? / Sq is obtained, and the adhesion is improved. In addition, by forming the CNT thin film including the adhesive, the peeling of the CNT transparent electrode can be prevented during the photo etching process, and the adhesion to the flexible substrate can be secured. As a result, it can replace ITO, which is transparent electrode of LCD panel, and CNT transparent electrode which can be applied to TSP (Touch Screen Panel) and solar cell electrode can be manufactured.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, Of the right.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exemplary view of an island failure that occurs upon application in accordance with an embodiment of the present invention. FIG.

2 is a graph showing changes in sheet resistance and transmittance according to the ratio of the adhesive agent according to an embodiment of the present invention.

3 is a flowchart showing a method of manufacturing a carbon nanotube transparent electrode including an adhesive component used as a first embodiment of the present invention.

4 is a first substrate structure having a carbon nanotube thin film applied to the first embodiment of the present invention.

5 is a second substrate structure having a carbon nanotube thin film applied to the second embodiment of the present invention.

6 is a third substrate structure having a carbon nanotube thin film applied to an embodiment of the present invention.

[Description of Reference Numerals]

10: substrate 30: carbon nanotube thin film

50: Adhesive film

Claims (16)

Board; A carbon nanotube thin film formed by coating a carbon nanotube dispersion solution obtained by dispersing carbon nanotubes (CNT) in an organic solvent on the substrate; And And an adhesive film formed by applying a mixed solution obtained by mixing an adhesive solution and the carbon nanotube dispersion solution onto the carbon nanotube thin film, Wherein the mixing ratio of the adhesive solution and the carbon nanotube dispersion solution is 1:20 to 1:30. The method according to claim 1, Wherein the adhesive solution is a mixed solution of an adhesive and a solvent. 3. The method of claim 2, The adhesive may be selected from the group consisting of a polyimide, an acrylic resin, a polyurethane resin, an ethercellulose, an epoxy resin, a polyvinyl chloride solvent (PVC) Wherein the carbon nanotube is one selected from the group consisting of silicone adhesives, styrene-butadiene rubber, and derivatives thereof. The method of claim 3, Wherein the mixing ratio of the adhesive and the solvent is 1:10 to 1:30. delete The method according to claim 1, Wherein the adhesive film is formed by applying a solution prepared by mixing the adhesive solution and the carbon nanotube dispersion solution. The method according to claim 1, Wherein the substrate is flexible. i) forming a carbon nanotube thin film by coating a carbon nanotube dispersion solution in which carbon nanotubes (CNTs) are dispersed in a solvent on a substrate; And ii) applying a solution of the carbon nanotube dispersion solution and an adhesive solution to the carbon nanotube thin film to form an adhesive film, Wherein the mixing ratio of the adhesive solution and the carbon nanotube dispersion solution is 1:20 to 1:30. 9. The method of claim 8, And further comprising a heat treatment step. 9. The method of claim 8, Wherein the forming of the thin film is performed by any one of a slit coating method, a spin coating method, a spray coating method, a filtration method, and a bar coating method. 9. The method of claim 8, Wherein the adhesive solution is a mixed solution of an adhesive and a solvent. 12. The method of claim 11, The adhesive may be selected from the group consisting of a polyimide, an acrylic resin, a polyurethane resin, an ethercellulose, an epoxy resin, a polyvinyl chloride solvent (PVC) Wherein the carbon nanotube is one selected from the group consisting of silicone adhesives, styrene-butadiene rubber, and derivatives thereof. 13. The method of claim 12, Wherein the mixing ratio of the adhesive and the solvent is 1:10 to 1:30. delete 9. The method of claim 8, Wherein a plurality of adhesive films are formed by applying a solution prepared by mixing the adhesive solution and the carbon nanotube dispersion solution. A liquid crystal display device using the carbon nanotube transparent electrode according to any one of claims 1 to 4, 6, and 7.

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