KR100987993B1 - Carbon nano tube film having excellent conductivity and optical transparency, and electronic devices and optical transmission type electrode obtained by using thereof - Google Patents

Abstract

The present invention provides a method of improving the bonding strength between carbon nanotube films and reducing the electrical bonding resistance between carbon nanotubes in a carbon nanotube film, and using the carbon nanotube film having excellent electrical conductivity and light transmittance. A method of manufacturing a device and a light transmissive electrode, comprising: preparing a substrate on which carbon nanotubes are adsorbed by using arc discharge, and then surface treating the substrate with an organic solvent to arrange the carbon nanotubes horizontally The resulting carbon nanotube film was heated in an oxidizing gas atmosphere to remove carbon nanoparticles other than amorphous carbon and carbon nanotubes, and catalyst metal particles were removed with an acidic solution to improve electrical conductivity and light transmittance. Through photoresist coating, exposure fixation, SOG coating, and thin film deposition It is possible to manufacture electronic devices, and it is composed of manufacturing electrodes of fine pattern form.

According to the method of the present invention, a large area can be obtained by introducing a horizontal arrangement of carbon nanotubes together with the production of a carbon nanotube film, and the electrical conductivity and light transmittance of the carbon nanotube film can be improved by a simple and inexpensive method. . In addition, the surface-treated carbon nanotube film is not only used for electromagnetic shielding, electrodes of electrochemical storage devices (secondary cells, fuel cells or supercapacitors), light transmitting electrodes, but also for carbon nanotube transistors, sensor elements, and organic and inorganic pollutants. It can be used in a filter that can exhibit a selective adsorption performance for.

Carbon nanotube film, horizontal arrangement, organic solvent, electrical conductivity, light transmittance

Description

Carbon nanotube film having excellent conductivity and optical transparency, and electronic devices and optical transmission type electrode obtained by using according to carbon nanotube film having excellent electrical conductivity and light transmittance.

The present invention relates to a carbon nanotube film having excellent electrical conductivity and light transmittance, and an electronic device and a light transmitting electrode obtained therefrom, and more specifically, to a carbon nanotube of a carbon nanotube film. By increasing the bonding force between substrates and increasing the probability of electrical bonding between carbon nanotubes in the carbon nanotube film to reduce the electrical resistance of the carbon nanotube film, and using the carbon nanotube film having excellent electrical conductivity and light transmittance A method of manufacturing an electronic device and a light transmitting electrode.

Multi-walled carbon nanotubes have a diameter of several tens to hundreds of nanometers, and the structure is largely anisotropic, ranging from several micros to hundreds of microns. In addition, it is mechanically strong (about 100 times as much as steel), has excellent chemical stability, high thermal conductivity, and hollow characteristics. Such carbon nanotubes are actively applied to electromagnetic shielding, electrodes of electrochemical storage devices (secondary cells, fuel cells or supercapacitors), field emission displays, electronic amplifiers, or gas sensors.

Carbon nanotubes have a specific surface area of 100 to 400 m 3 / g, which is smaller than other activated carbons, but shows excellent performance in electrochemical storage, gas sensors, and electromagnetic shielding. In addition, carbon nanotubes with increased specific surface area are expected to exhibit more excellent properties.

In particular, carbon nanotubes with increased specific surface area are filters for wastewater treatment, adsorption and removal of harmful exhaust gases from incinerators and chemical process facilities, removal of traces of harmful gases in electrical and electronic manufacturing, and removal of harmful substances and bacteria. Applicable to

Therefore, various methods for increasing the specific surface area have been attempted. For example, in Korean Patent Application No. 1998-7009168, a thin carbon film is coated on the synthesized carbon nanofibers, and then steam, carbon dioxide or air is used to Methods of activation through methods such as selective oxidation and methods of activating surfaces by reacting or contacting one or more materials to attach functional groups are disclosed. However, such a method requires a separate process of first coating a thin carbon film on carbon nanofibers, and thus has a problem in that cost increases during mass production.

In addition, Korean Patent Application No. 2002-0030684 is mixed with 30 to 1000 parts by weight of an alkali compound based on 100 parts by weight of carbon nanotubes or carbon nanofibers in a vacuum atmosphere or an inert atmosphere, and then 20 minutes to 120 minutes at 500 to 1500 ° C. Disclosed is a method of treating a surface of a carbon nanotube or carbon nanofiber, and a device used therein, the method comprising treating the carbon nanotube or the carbon nanofiber. However, the treatment at high temperature is a heat treatment method for increasing the crystallinity of carbon nanotubes or inducing the doping of alkali metals in the carbon nanotubes. It is not to carry out the process.

In addition, according to Zhong Chen's "Transparent, conductive carbon nanotube films", 2004, Science, carbon nanotubes were dispersed and formed using a filtering process to form a carbon nanotube film on a filter and placed it on a substrate. A technique of forming a carbon nanotube film by performing a two-step process of melting a filter is disclosed, but the filter used in the process uses a nano-sized membrane, and uses a polymer-based nanomembrane and anodized aluminum oxide. In general, in this case, the size of the carbon nanotube film is determined by the size of the polymer-based nano-membrane filter, which generally does not exceed 10 cm, so the large-area process is limited and the process is cumbersome. There is a disadvantage that the tube film production time and cost is high.

Therefore, an object of the present invention is to solve the problems of the prior art and the technical problems that have been requested from the past.

That is, it is an object of the present invention to mount a carbon nanotube produced by the arc discharge method during the arc discharge and mount the substrate in the arc discharge chamber to adsorb it onto the substrate. By surface-treating the adsorbed substrate with an organic solvent, it is to provide a method for producing a carbon nanotube film that can increase the bonding strength between the carbon nanotubes and the substrate as well as large area.

Another object of the present invention is to arrange the carbon nanotubes horizontally by this method, thereby increasing the bonding force between the carbon nanotubes and the substrate and the electrical bonding probability between the carbon nanotubes, thereby lowering the electrical resistance of the carbon nanotube film, thereby reducing the electrical conductivity and the light transmittance. The superiority of the present invention is to provide a highly functional activated carbon nanotube film that can be used for electrodes or filters.

Another object of the present invention is to provide a method for producing an electronic device and a light transmitting electrode from the carbon nanotube film thus obtained.

According to one aspect of the invention,

After the substrate is inserted into the arc discharge chamber, an arc discharge causes the single-walled or multi-walled carbon nanotubes to adsorb weakly to the substrate during the cooling and condensation of the carbon atoms and the catalytic metal atoms vaporized by the arc plasma. 1 step,

A second step of surface treatment using an organic solvent on the substrate having undergone the first step; carbon of the carbon nanotube film comprising a carbon nanotube film including a horizontally arranged carbon nanotube film on the substrate; The present invention provides a method of reducing the electrical resistance of a carbon nanotube film by increasing the bonding force between the nanotube and the substrate and increasing the electrical bonding probability between the carbon nanotubes in the carbon nanotube film.

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According to the second aspect of the present invention,

Carbon nanotubes prepared by one method are arranged horizontally to provide a carbon nanotube film with increased electrical conductivity and light transmittance.

According to the third aspect of the present invention,

Coating a metal layer, a metal alloy layer, a metal oxide, an organic thin film, a nitride, a ceramic material, and a photoresist layer on the carbon nanotube film of the second aspect; It provides an electronic device manufacturing process, an electrical conductivity and a light transmittance excellent in manufacturing an electronic device comprising a.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

In the present invention, the single-walled or multi-walled carbon nanotubes are weakly bonded to the substrate in the process of cooling and condensing the carbon atoms and the catalytic metal atoms vaporized by the arc plasma after the substrate is inserted into the arc discharge chamber. A carbon nanotube film comprising a first step of adsorbing, a second step of surface treatment using an organic solvent on the substrate subjected to the first step; .

The arc discharge method of the present invention can be used without limitation as long as it is a conventionally available method, but is not limited thereto. For example, the inside of the chamber is made into a vacuum and argon gas, helium gas or hydrogen at a pressure of 300 to 400 torr. While flowing gas, when a DC voltage of 10 to 30 V is applied thereto while the gap between the anode carbon rod and the cathode carbon rod installed in the chamber is approximately 1 mm, an arc is generated between the two electrodes. By discharging, composite multi-walled carbon nanotubes (MWNT: MultiWall NanoTube) or single-walled carbon nanotubes (SWNT: SingleWall NanoTube) are manufactured. The type, size, and yield of carbon nanotubes are determined by the amount of arc discharge current, application time, voltage, catalyst, and inert atmosphere. For reference, in the case of multi-walled carbon nanotubes, the multi-walled carbon nanotubes grown under the influence of the arc plasma directly on the graphite plate on the cathode side cannot be directly grown on the substrate by the arc discharge method. In the case of single-walled carbon nanotubes and double-walled carbon nanotubes synthesized by condensation and cooling of vaporized carbon and catalytic metal, single-walled carbon nanotubes and double-walled carbon nanotubes are attached to the substrate without being affected by direct arc plasma. Can be.

The organic solvent is a polar organic solvent in consideration of the fact that carbon nanotubes have a very high hydrophobicity and most carbon nanotubes are separated from the substrate and float on water as well as nonpolar materials. In other words, methanol, acetone, ethanol, trichloroethylene, isopropyl alcohol, toluene, n-hexane, DMF and the like should be used. This is because the polar organic solvent-containing solution is not dispersed without the use of a separate surfactant.

When such a polar organic solvent reacts with a nonpolar material such as carbon nanotubes, rapid condensation occurs to reduce surface energy. Accordingly, the condensation of carbon nanotubes is in a horizontal arrangement on a substrate.

In addition, the amount of the organic solvent used may be more than a capacity to completely immerse the substrate when immersed and a capacity to completely cover the surface when applied to the surface, preferably, if the amount is too small based on the weight of the substrate The organic solvent acts only on a part of the substrate to be used, so that the horizontal arrangement effect of the carbon nanotubes may not be improved, and when too much, the carbon nanotubes may have too much influence upon the adsorption of carbon nanotubes. Therefore, it is preferable that it is 30-1000 weight part, It is more preferable that it is 50-700 weight part, It is most preferable that it is 100-500 weight part. Such an organic solvent can be used by being immersed or applied to a substrate.

The exact reaction of the horizontal arrangement of carbon nanotubes by surface treatment of organic solvents is not known.However, since carbon nanotubes are very hydrophobic, carbon nanotubes fall off the substrate when treated in an aqueous solution-based solution. In the case of organic solvents, carbon nanotubes are inferred in the form of agglomerates on the substrate. Also, when the atmosphere is changed from air to organic solvents, the agglomeration of carbon nanotubes occurs quickly and is horizontally arranged on the substrate. It is considered to be. (See Figure 1C)

The substrate may include, but is not limited to, a corning glass, a soda lime glass substrate, a Si substrate on which SiO ₂ is deposited, a quartz substrate, a sapphire substrate, a GaAs substrate, a MgO substrate, and the like. Possible carbon nanotube film thickness can be controlled by controlling the arc discharge time, and increasing the arc discharge time can increase the thickness of the carbon nanotube film. The diameter of the carbon nanotubes constituting the film of the carbon nanotubes is a bundle structure in the case of the single-walled carbon nanotubes, and the thickness of the bundle structure is preferably about 30 nm or less.

In this way, it is preferable to produce carbon nanotube films in which carbon nanotubes are arranged horizontally, and then raise the temperature of the substrate in an oxidizing gas atmosphere to remove carbon nanoparticles other than amorphous carbon and carbon nanotubes. The oxidizing gas atmosphere may be made using an atmosphere selected from air, oxygen, ozone, and nitrogen oxide.

At this time, the temperature of the reaction, as described above, to effectively remove the amorphous carbon in the temperature range as 300 to 420 ℃, ignition of amorphous carbon is made at about 400 degrees, ignition of carbon nanotubes 450 degrees This is because the carbon nanotubes are oxidized and removed at a high temperature because the carbon nanotubes are removed at a high temperature, and amorphous carbon is not removed at too low a temperature.

In addition, the treatment time is preferably 20 to 360 minutes as described above, if the treatment time is too short, the amorphous carbon is not sufficiently removed, on the contrary too long is economically undesirable.

At the same time or sequentially, it is preferable to remove the catalyst metal particles and the catalyst metal oxide by treating with one or more acid solutions selected from nitric acid, hydrochloric acid, sulfuric acid, aqua regia, hydrofluoric acid solution. For reference, carbon nanotubes grown by the arc discharge method contain catalytic metal particles (a mixture of Ni, Fe, Co, Mo, Pt, Pd, Au, or single metal particles). It is strongly adsorbed on the surface and the tip, and it can be effectively removed by treating with acid at 30-60% concentration, especially for 5 minutes or more.

In this case, when the acid having a low concentration is used, the removal time of the catalyst metal particles will be longer, and the etching process time is too short when the acid having a high concentration is used, which is not preferable.

The carbon nanotubes prepared by the above-described method may be horizontally arranged to provide a carbon nanotube film having increased electrical conductivity and light transmittance. As described above, since the carbon nanotube film prepared by the present invention is arranged horizontally on the substrate and has a high bonding strength with the substrate, the carbon nanotube film falls off from the substrate during the thermal oxidation process and the wet etching process of the carbon nanotubes. The phenomenon can be prevented.

The method of the present invention can be easily applied not only to introducing a horizontal arrangement of carbon nanotubes, but also to introducing functional groups on the surface of carbon nanotubes using other compounds. It should be interpreted as being included in the category.

In addition, depositing a metal layer, a metal alloy layer, a metal oxide, an organic thin film, a nitride, a ceramic material on the carbon nanotube film, coating a photoresist layer; Through the electronic device and the light transmission type electrode having excellent electrical conductivity and light transmittance can also be manufactured.

Specifically, the exposure process through the photoresist coating, the carbon nanotube film pattern formed through this, it is possible to manufacture a microelectronic device by forming a film pattern, by depositing an insulating layer such as nitride and ceramic on the microelectronic device, It is possible to fabricate an independent electronic device, and by forming an electrode such as a metal layer on the portion, it is possible to manufacture a carbon nanotube film transistor and a carbon nanotube film diode.

In addition, through the formation of the electrode layer, it is possible to manufacture a gas sensor and biosensor, and to produce a light emitting device and a light receiving device through the deposition of organic semiconductor and inorganic semiconductor material, can be utilized in the production of carbon nanotube solar cell. .

According to the method of the present invention, in addition to the carbon nanotube film production, the horizontal arrangement of the carbon nanotubes can be introduced to enable a large area, and the electric conductivity and the light transmittance of the carbon nanotube film can be increased by a simple and inexpensive method. . In addition, the surface-treated carbon nanotube film is not only used for electromagnetic shielding, electrodes of electrochemical storage devices (secondary cells, fuel cells or supercapacitors), light transmitting electrodes, but also for carbon nanotube transistors, sensor elements, and organic and inorganic pollutants. It can be used in a filter that can exhibit a selective adsorption performance for.

Hereinafter, the content of the present invention will be described in more detail with reference to Examples according to the present invention, but the scope of the present invention is not limited thereto.

[ Example  1: surface treatment of organic solvent]

After inserting the Si substrate on which SiO ₂ is deposited into the arc discharge chamber, single-walled or multi-walled carbon nanotubes are formed during the cooling and condensation of the carbon atoms and the catalytic metal atoms vaporized by the arc plasma. Adsorbed by weak binding to. The substrate was immersed for several seconds at a capacity such that the substrate was completely immersed in methanol. The carbon nanotube film obtained by the conventional arc discharge method is shown in FIG.

Conventionally obtained carbon nanotube films are entangled with each other in a state in which almost all carbon nanotubes are not attached to a substrate, as shown in FIG. 1 (a) (b), whereas the carbon nanotube films according to the method of the present invention are shown in FIG. 1. As shown in (c), it was confirmed that the carbon nanotubes were not only horizontally arranged on the substrate but also condensed with each other to form a film during treatment with an organic solvent such as ethanol. Thus, it can be inferred that surface treatment using an organic solvent can increase the bonding strength between the substrate and the carbon nanotubes.

[ Example  2: oxidative Atmosphere  Heat treatment and acid solution treatment]

The carbon nanotube film obtained in Example 1 was performed at 400 ° C. for 60 minutes in an oxygen atmosphere to remove carbon nanoparticles other than amorphous carbon and carbon nanotubes. In this case, in order to confirm the oxidizing gas atmosphere of the carbon nanotube film, TGA data was measured and shown as a graph in FIG. 2.

As shown in Figure 2, the removal of amorphous carbon is made at 360 ℃, it was confirmed that the weight reduction and the combustion of carbon nanotubes almost does not occur at 400 ℃.

In addition, in order to confirm the heat treatment temperature under an oxidizing atmosphere, DTA measurement confirmed that the oxidation reaction of amorphous carbon occurred at 400 ° C. and that the oxidation reaction of single-walled carbon nanotubes occurred at 450 ° C. From this, the temperature during the heat treatment was 400 ° C. It was confirmed that it is preferable to carry out in the vicinity. Scanning electron microscope (SEM) photographs of the specimens heat-treated under an oxidizing atmosphere are shown in FIG. 3. As shown in FIG. 3, the horizontal arrangement was clearly observed in the scanning electron micrograph.

Then 5 minutes in 50% hydrochloric acid solution to remove the catalyst metal and catalyst metal oxide, the purification Transmittance change according to the process and the optical properties of the film obtained through the thermal oxidation purification and acid purification process was measured and shown in FIG.

As shown in FIG. 4, the electrical conductivity and the light transmittance of the obtained carbon nanotube film could be increased, which was arranged by horizontally arranging the carbon nanotubes on the substrate by the organic solvent application process of Example 1 described above. In addition to increasing the adhesion between the tubes, it is proved that the light transmittance of the carbon nanotube film can be increased by increasing the probability of electrical bonding between the carbon nanotubes.

Those skilled in the art to which the present invention pertains, various applications and modifications are possible within the scope of the present invention based on the above description.

1 is a photograph (1a) (1b) not treated with an organic solvent of a carbon nanotube film grown by an arc discharge method and a photograph (1c) treated with an organic solvent according to an embodiment of the present invention;

2 is a graph showing TGA data confirming an oxidizing gas atmosphere of a carbon nanotube film grown by an embodiment of the present invention;

3 is a scanning electron micrograph of a specimen heat-treated under an oxidizing atmosphere according to one embodiment of the present invention;

Figure 4 shows the optical properties of the film made of carbon nanotubes of high purity through the change in permeability and thermal oxidation purification and acid purification process of the carbon nanotube film grown by an embodiment of the present invention. One drawing and a graph.

Claims (16)

After the substrate is inserted into the arc discharge chamber, an arc discharge causes the single-walled or multi-walled carbon nanotubes to adsorb weakly to the substrate during the cooling and condensation of the carbon atoms and the catalytic metal atoms vaporized by the arc plasma. 1 step; A second step of surface treatment using an organic solvent on the substrate having undergone the first step; carbon of the carbon nanotube film comprising a carbon nanotube film including a horizontally arranged carbon nanotube film on the substrate; The method of reducing the electrical resistance of carbon nanotube films by increasing the bonding force between nanotubes and substrates and increasing the probability of electrical bonding between carbon nanotubes in carbon nanotube films. The method of claim 1, wherein the organic solvent used in the surface treatment is selected from methanol, acetone, ethanol, trichloroethylene, isopropyl alcohol, toluene, n-hexane and DMF. The method of claim 2, wherein the organic solvent is applied to an amount that will submerge the substrate or cover the surface of the substrate to an extent that the substrate is completely immersed. The method of claim 1, wherein the substrate is selected from a corning glass, a soda-lime glass substrate, a Si substrate on which SiO ₂ is deposited, a quartz substrate, a sapphire substrate, a GaAs substrate, and a MgO substrate. The method of claim 1, further comprising: a third step of heat treating the substrate in an oxidizing gas atmosphere following the second step of surface treatment; Method further comprising a The method of claim 5, wherein the oxidizing gas atmosphere is selected from air, oxygen, ozone, nitrogen oxides. The method of claim 5, wherein the heat treatment conditions are performed for 20 to 360 minutes in the range of 300 to 420 ℃ 6. The method of claim 5, further comprising: a fourth step of treating with an acidic solution following the third step of heat treatment; Method further comprising a The method of claim 8, wherein the acidic solution is treated with at least one selected from nitric acid, hydrochloric acid, sulfuric acid, aqua regia, hydrofluoric acid solution at a concentration of 30 to 60%. The carbon nanotube film of which the carbon nanotubes prepared by the method of any one of claims 1 to 9 are arranged horizontally to increase electrical conductivity and light transmittance. The method of manufacturing an electronic device comprising sequentially performing a photoresist coating process, an exposure process, an SOG coating process, and a thin film deposition process on the carbon nanotube film of claim 10. A method of manufacturing a light transmissive electrode comprising sequentially performing a photoresist coating process, an exposure process, an SOG coating process, and a thin film deposition process on the carbon nanotube film of claim 10 The method of claim 11, wherein the photoresist coating process comprises depositing a metal layer, a metal alloy layer, a metal oxide, an organic thin film, a nitride, and a ceramic material on the carbon nanotube film to coat the photoresist layer. An electronic device having excellent electrical conductivity and light transmittance obtained by the method of claim 11 A light transmissive electrode excellent in electrical conductivity and light transmittance obtained by the method of claim 12 The method of claim 12, wherein the photoresist coating process comprises depositing a metal layer, a metal alloy layer, a metal oxide, an organic thin film, a nitride, and a ceramic material on the carbon nanotube film to coat the photoresist layer.

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