KR20130047795A - Non-covalent functionalized carbon nanotube and preparing method of the same, composite using the same, and thin film transistor using the composite - Google Patents

Abstract

PURPOSE: A non-covalent functionalized carbon composite is provided to uniformly dispersed in hydrophobic solution a polymer such as P3HT and to improve mobility of a filed effect of an organic thin film transistor 15 times. CONSTITUTION: A manufacturing method of a non-covalent functionalized carbon nanotube comprises a step of conducting reaction of an aromatic compound with aliphatic amine to obtain an oleophilic surfactant which contains an aromatic compound modified by aliphatic amide(S2); a step of obtaining a non-covalent functionalized carbon nanotube by mixing the oleophilic surfactant and carbon nanotubes(S3). The aromatic compound contains carboxyl functional group. The aromatic compound comprises a pyrene compound, porphyrin-basd compound, or a combination thereof. [Reference numerals] (AA,BB) Start; (S1) Obtain an aromatic compound with an acyl group by introducing an acyl group into an aromatic compound; (S2) Obtain an oleophilic surfactant by reacting the acyl group introduced aromatic compound with aliphatic amine; (S3) Obtain a non-covalent functionalized carbon nanotube by mixing the oleophilic surfactant with carbon nanotube and processing

Description

NON-COVALENT FUNCTIONALIZED CARBON NANOTUBE AND PREPARING METHOD OF THE SAME, COMPOSITE USING THE SAME, AND THIN FILM TRANSISTOR USING THE COMPOSITE}

The present application relates to a non-covalent functionalized carbon nanotube and a method for manufacturing the same, an organic material / carbon nanotube composite using the non-covalent functionalized carbon nanotube, and an organic thin film transistor using the organic material / carbon nanotube composite.

Over the past decade, π-conjugated oligomeric or polymeric semiconductor materials have been proposed as good candidates for flexible electronics that replace inorganic materials due to solution process compatibility. Solution-fairness has numerous advantages such as large area application, structural flexibility, low temperature processability and low cost. In such materials, regioregular poly (3-hexiophene) (P3HT) has been used as one of the most promising conjugated polymers and can typically be deposited by solution processes as the active material of organic thin film transistors (OTFTs). It can be. P3HT has higher hole mobility than other solution-processed organic materials due to its good solubility in organic solvents and the properties that affect charge transfer in the special lamellar microstructures of the pi-pie stacked chains. However, spin-coated P3HT loses crystallinity during evaporation of the solvent, and most of them show low charge mobility. Thus, carbon nanotubes (CNT) were added to P3HT to increase the charge mobility of P3HT.

The carbon nanotubes are known to have excellent properties such as high strength, modulus of elasticity, electrical conductivity, thermal conductivity, specific surface area, and contrast ratio, and research has been conducted to apply them to nanotechnology. Despite these excellent properties, however, carbon nanotubes are one-dimensional tube shapes with a diameter of several nanometers (nm) and lengths of several tens of micrometers (μm), and are difficult to dissolve or disperse because they exist as aggregates. Is difficult to use directly.

There is an acid treatment method using a strong acid to disperse carbon nanotubes in a solvent. By chemically oxidizing the surface of the nanotube and the tip portion using a mixed acid such as nitric acid or sulfuric acid, oxygen-containing functional groups such as -C = O, -COOH, and -OH can be introduced in a covalent manner. In this case, the attraction force with the water molecules increases and the carbon nanotubes are negatively charged, thereby generating an electrostatic repulsion force, thereby obtaining a stable carbon nanotube dispersion solution without generating precipitation. An open tip may be formed during the acid treatment, and through such treatment, the carbon nanotubes may form an electrostatically stable solution in an aqueous solution or an alcohol solution. However, in the case of such covalent functionalization, defects are formed on the surface of the carbon nanotubes by acid treatment, thereby reducing the excellent electrical properties of the carbon nanotubes.

On the other hand, the use of the carbon nanotubes to which the above-described hydrophilic group is introduced to make an organic material / carbon nanotube composite such as a polymer / carbon nanotube composite is not suitable in terms of dispersibility in a polymer having mostly hydrophobic properties.

In recent studies, non-covalent functionalization of CNTs by pyrene molecules has been disclosed as a new route to overcome the disadvantages of covalent functionalization. Pyrene molecules have flat conjugated double bonds with sp ² structures, such as CNTs, and are easily adsorbed on the surface of CNTs by π-π interactions. For example, when aminopyrene was used [ Wang, S., Wang , X., Jiang , SP, Langmuir , 2008 , 24, pp . 10505-10512. ], When pyrene carboxylic acid (PCA) is used [ Simmons , TJ, Bult , J., Hashim , DP, Linhardt , RJ, Ajayan , PM, ACS Nano , 2009 , 3, pp . 865-870. ], And pyrene butyric acid (PBA) [ Ham , HT, Choi , YS, Chee , MG, Cha , MH, Chung , IJ, Polym . Eng . Sci . 2008 , 48, pp . 1-10. ], And these various pyrene molecules make it possible to attach functional groups on CNTs without generating any defects on the CNTs. However, the hydrophilic functional groups of the pyrene molecules make it difficult to disperse CNTs at hydrophobic sites such as P3HT.

The present application relates to a non-covalent functionalized carbon nanotube and a method for manufacturing the same, an organic material / carbon nanotube composite using the non-covalent functionalized carbon nanotube, and an organic thin film transistor using the organic material / carbon nanotube composite.

However, the problem to be solved by the present application is not limited to the above-mentioned problem, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

A first aspect of the present application provides a method of preparing a non-covalent functionalized carbon nanotube, comprising:

Reacting the aromatic compound with an aliphatic amine to obtain a lipophilic surface modifier comprising the aromatic compound modified with aliphatic amides;

Treating the lipophilic surface modifier with carbon nanotubes to obtain a non-covalent functionalized carbon nanotube by the lipophilic surface modifier.

A second aspect of the present application is a non-covalent functionalized carbon nanotube manufactured by the method according to the first aspect of the present application, wherein the lipophilic surface modifier is non-covalently functionalized on the surface of the carbon nanotube. To provide carbon nanotubes.

A third aspect of the present application provides an organic material / carbon nanotube composite comprising a non-covalent functionalized carbon nanotube according to the second aspect of the present application dispersed in an organic material.

A fourth aspect of the present application provides an organic thin film transistor comprising the organic material / carbon nanotube composite according to the third aspect of the present application as a semiconductor channel layer.

Provided herein is a non-covalent functionalized carbon nanotube and a method of manufacturing the same, an organic material / carbon nanotube composite using the non-covalent functionalized carbon nanotube, and an organic thin film transistor using the organic material / carbon nanotube composite. Herein, new non-covalent functionalization of carbon nanotubes can be systematically presented by the use of lipophilic surface modifiers comprising aromatic compounds such as pyrene molecules modified with hydrophobic long alkyl chains. The non-covalent functionalized carbon nanotubes can be well dispersed in a hydrophobic solution and a polymer such as P3HT. P3HT in an organic thin film transistor using a complex with a polymer such as P3HT in which the non-covalent functionalized carbon nanotubes are dispersed, as a semiconductor channel layer, by improving the dispersion degree in a polymer such as P3HT of the non-covalent functionalized carbon nanotubes, Compared to the organic thin film transistor including only, the field effect mobility can be achieved more than 15 times.

1 is a process flow chart for explaining a method of manufacturing a non-covalent functionalized carbon nanotube according to an embodiment of the present application.
FIG. 2A shows unmodified pyrene, FIG. 2B shows pyrene modified with aliphatic amine in one embodiment of the present application, and FIG. 2C shows FT-IR spectrum of carbon nanotubes adsorbed modified pyrene.
3 is a pyrene single molecule unmodified, a green line is a pyrene single molecule modified with an aliphatic amine in one embodiment of the present application, a black line is a carbon nanotube not functionalized, a red line is In one embodiment, the results of ultraviolet-visible absorption spectra of carbon nanotubes functionalized with modified pyrene single molecules are shown.
4A and 4B are scanning electron micrographs of carbon nanotubes functionalized using unfunctionalized carbon nanotubes in a nonpolar solvent and pyrene monomolecules modified with aliphatic amines according to an embodiment of the present application, respectively. .
5 is carbon nanotubes not treated with black lines, and red lines are carbon nanotubes functionalized using pyrene monomolecules modified according to one embodiment of the present application as a result of Raman spectroscopy, and blue lines are covalent functionalization methods. This is the result of acid treated carbon nanotubes.
6A is a structural conceptual diagram of an OTFT manufactured according to an embodiment of the present application.
6B is an output characteristic curve of an OTFT manufactured according to an embodiment of the present application.
6c is a transfer characteristic curve of an OTFT manufactured according to an embodiment of the present application.
Figure 6d shows the charge mobility according to the concentration of the non-covalent functionalized carbon nanotubes of the OTFT prepared according to an embodiment of the present application.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. It should be understood, however, that the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In the drawings, the same reference numbers are used throughout the specification to refer to the same or like parts.

Throughout this specification, when a part is referred to as being "connected" to another part, it is not limited to a case where it is "directly connected" but also includes the case where it is "electrically connected" do.

Throughout this specification, when a member is located "on" another member, this includes not only when one member is in contact with another member but also when another member exists between the two members.

Throughout this specification, when an element is referred to as "including " an element, it is understood that the element may include other elements as well, without departing from the other elements unless specifically stated otherwise. The terms "about "," substantially ", etc. used to the extent that they are used throughout the specification are intended to be taken to mean the approximation of the manufacturing and material tolerances inherent in the stated sense, Accurate or absolute numbers are used to help prevent unauthorized exploitation by unauthorized intruders of the referenced disclosure. The word " step (or step) "or" step "used to the extent that it is used throughout the specification does not mean" step for.

Throughout this specification, the term “combination of these” included in the expression of the mark of the form refers to one or more mixtures or combinations selected from the group consisting of the elements described in the mark of the form of Markus, wherein the components It means to include one or more selected from the group consisting of.

Hereinafter, exemplary embodiments will be described in detail with reference to the accompanying drawings. However, it is not limited to these embodiments and examples herein.

A first aspect of the present application provides a method of preparing a non-covalent functionalized carbon nanotube, comprising:

Reacting the aromatic compound with an aliphatic amine to obtain a lipophilic surface modifier comprising the aromatic compound modified with aliphatic amides;

Treating the lipophilic surface modifier with carbon nanotubes to obtain a non-covalent functionalized carbon nanotube by the lipophilic surface modifier.

According to the exemplary embodiment of the present application, the aromatic compound may be an aromatic compound having an acyl group introduced thereto, but is not limited thereto. The acyl group introduced into the aromatic compound reacts with the aliphatic amine, thereby obtaining a lipophilic surface modifier including the aromatic compound modified by aliphatic amides.

According to one embodiment of the present application, the lipophilic surface modifier is adsorbed on the surface to provide a non-covalent functionalized carbon nanotube. The lipophilic surface modifier may be a compound having functional groups capable of being adsorbed by a non-covalent bond to carbon nanotubes and functional groups having dispersibility in a low polar or nonpolar organic solvent.

In the present specification, a low polar or nonpolar organic solvent includes a high polar solvent such as a protonic solvent containing -OH such as water or alcohol, or a solvent containing> C = O such as acetone or dimethylformamide (DMF). Means the solvent except. The lipophilic surface modifier may have an aromatic hydrocarbon group at one end to be attached to the surface of the carbon nanotubes by π-electron interaction. At the same time, the other end may have an aliphatic hydrocarbon group.

The aromatic hydrocarbon group is not particularly limited as long as the aromatic hydrocarbon group is non-covalently adsorbed with a π-π stacking force with a graphite plate having a hexagonal honeycomb structure composed of sp ² carbon on the surface of the carbon nanotube, for example, a pyrene-based compound, Porphyrin-based compound and combinations thereof may be selected from the group consisting of, but is not limited thereto.

The aliphatic hydrocarbon group imparts lipophilic so that carbon nanotubes are well dispersed in a low polar or nonpolar organic solvent. The organic solvent may dissolve an organic material such as a polymer, and at the same time, the solvent is not particularly limited as long as the carbon nanotube is substantially uniformly dispersed therein. For example, the organic solvent may include one selected from the group consisting of chloroform, chlorobenzene, dichlorobenzene, benzene, and toluene, but is not limited thereto.

The aliphatic hydrocarbon may have an appropriate carbon number, for example, about 6 to about 20 carbon atoms, but is not limited thereto. If the carbon number is less than the range of carbon nanotubes dispersibility may be low, if the carbon number exceeds the range may form a composite with a conductive polymer may lower the conductivity.

The chain including the aromatic hydrocarbon terminal and the chain including the aliphatic hydrocarbon terminal may have a structure connected to each other by an amide bond. The amide bond structure may be derived from the carboxyl group and the amine group included in the aromatic hydrocarbon raw material and the aliphatic hydrocarbon raw material necessary for preparing the lipophilic surface modifier.

According to an embodiment of the present disclosure, the aromatic compound may include a carboxyl functional group, and may include, for example, "subscription 3", but is not limited thereto. For example, the aromatic compound containing the carboxyl functional group is 1-pyrene carboxylic acid, 1-pyrene acetic acid, 1-pyrene butanoic acid, 2-carboxy porphyrin, 3-carboxy porphyrin, 4-carbo It may include, but is not limited to, at least one selected from the group consisting of carboxylic porphyrin, 5-carboxy porphyrin, 6-carboxy porphyrin, 7-carboxy porphyrin, and 8-carboxy porphyrin.

According to an embodiment of the present disclosure, the introduction of the acylating group is performed by stirring thionyl chloride at about 65 ° C to about 75 ° C for about 10 to about 48 hours to the aromatic compound containing the carboxylic acid functional group. May be, but is not limited thereto.

According to one embodiment of the present application, the aliphatic amine may include, but is not limited to, a primary amine having about 6 to about 20 carbon atoms. For example, the aliphatic amine may include at least one selected from the group consisting of hexyl amine, octyl amine, decyl amine, dodecyl amine, tetradecyl amine, hexadecyl amine, and octadecyl amine, but is not limited thereto. It is not.

According to an embodiment of the present disclosure, the reaction of the acyl group with the aliphatic amine may be performed at about 50 ° C. to about 150 ° C., but is not limited thereto. In addition, the reaction of the acyl group and the aliphatic amine may be performed by stirring for about 1 to about 4 days, but is not limited thereto.

According to one embodiment of the present application, treating the lipophilic surface modifier by mixing with carbon nanotubes may include sonicating or stirring a mixture of the lipophilic surface modifier and carbon nanotubes in an organic solvent. However, it is not limited thereto. For example, the organic solvent may be selected from the group consisting of chloroform, chlorobenzene, dichlorobenzene, benzene, and toluene, but is not limited thereto.

According to one embodiment of the present application, the lipophilic surface modifier may be represented by the following Formula 1 or Formula 2, but is not limited thereto:

[Formula 1]

Pyrene- (CH ₂ ) _n -CONHR

Where n is 0 to 3,

R is an aliphatic hydrocarbon group having 6 to 20 carbon atoms; or,

[Formula 2]

Porphyrin-conhr

Wherein R is an aliphatic hydrocarbon group having 6 to 20 carbon atoms.

For example, the structure of Chemical Formula 1 may be one in which one of the hydrogen atoms of pyrene is substituted with-(CH ₂ ) _n -CONHR, but is not limited thereto.

For example, the structure of Formula 2 may be one of the hydrogen atom of porphyrin is substituted with -CONHR, but is not limited thereto.

The non-covalent functionalized carbon nanotubes described above may be coated with a lipophilic surface modifier to improve compatibility with organic materials including low polar or nonpolar solvents, various organic compounds, and polymers. In addition, there is no surface defect that may be generated in the conventional co-functionalization process.

The non-covalent functionalized carbon nanotubes according to the present application may be prepared using a process for treating a carbon nanotube surface with a lipophilic surface modifier. 1 is a process flow chart for explaining a method for producing a non-covalent functionalized carbon nanotube according to an embodiment of the present application.

Referring to FIG. 1, in step S1, an aromatic molecule having an acyl group is introduced by acylating an aromatic molecule having a functional group such as a carboxyl group. The aromatic compound having a functional group such as the carboxyl group may be at least one selected from the group consisting of pyrene, porphyrin, and derivatives thereof. The aromatic molecules having the carboxyl group include 1-pyrene carboxylic acid, 1-pyrene acetic acid, 1-pyrene butanoic acid, 2-carboxy porphyrin, 3-carboxy porphyrin, 4-carboxy porphyrin, 5-carbohydrate. At least one selected from the group consisting of carboxylic porphyrin, 6-carboxy porphyrin, 7-carboxy porphyrin, and 8-carboxy porphyrin. Thionyl chloride can be used as the acylating agent for the acylation of carboxylic acid functional groups. The acylation may be performed by stirring thionyl chloride with the aromatic molecule having the carboxyl group at about 65 ° C to about 75 ° C for about 10 to about 48 hours, but is not limited thereto. After the reaction is finished, the remaining acylating agent is removed, washed with a solvent such as tetrahydrofuran, and the remaining tetrahydrofuran is removed by drying in vacuo.

In step S2, the acyl group of the aromatic molecule is reacted with an aliphatic amine to produce a lipophilic surface modifier. By nucleophilic substitution of the acyl group, the halogen group of the acyl group is substituted with an amine having an aliphatic chain. The aliphatic amine may be a primary amine having about 6 to about 20 carbon atoms, but is not limited thereto. The carbon nanotubes to which the lipophilic surface modifier is adsorbed at the carbon number may have appropriate solvent dispersibility. More specifically, the aliphatic amine may be at least one selected from the group consisting of hexyl amine, octyl amine, decyl amine, dodecyl amine, tetradecyl amine, hexadecyl amine, octadecyl amine. The reaction of the acyl group with the aliphatic amine may be performed by stirring at about 80 ° C. to about 100 ° C. for 1 to 4 days, but is not limited thereto. It can be washed with chloroform to remove unreacted amine in the substituted result, but is not limited thereto.

In step S3, the non-covalent functionalized carbon nanotubes may be prepared by treating the surface of the carbon nanotubes with non-covalent functionalization. The non-covalent functionalization of the lipophilic surface modifier on the surface of the carbon nanotube may be performed by ultrasonication in an organic solvent. The organic solvent may be selected from the group consisting of chloroform, chlorobenzene, dichlorobenzene, benzene and toluene. Preferably, the organic solvent may be chloroform, but is not limited thereto. The final product may be separated from the organic solvent through centrifugation and washing, but is not limited thereto.

The non-covalent functionalized carbon nanotubes described above may be stored in a dry state or a solvent. In this case, chloroform or chlorobenzene may be used as the solvent, but is not limited thereto.

According to the above-described manufacturing method, a lipophilic surface modifier can be prepared by a simple method using an amide coupling reaction between a raw material containing an aromatic hydrocarbon and a raw material containing an aliphatic hydrocarbon, and the surface of the carbon nanotubes is lipophilic using the same. Can be modified.

A second aspect of the present application is a non-covalent functionalized carbon nanotube manufactured by the method according to the first aspect of the present application, wherein the lipophilic surface modifier is non-covalently functionalized on the surface of the carbon nanotube. To provide carbon nanotubes.

According to an embodiment of the present disclosure, in the non-covalent functionalized carbon nanotube, the lipophilic surface modifier may include a chain and an aliphatic hydrocarbon containing an aromatic hydrocarbon terminal to be attached to the surface of the carbon nanotube by π electron interaction. The chain including the terminal may have a structure connected to each other by an amide bond, but is not limited thereto.

All of the contents described for the method of manufacturing the non-covalent functionalized carbon nanotubes according to the first aspect of the present application may be applied to the non-covalent functionalized carbon nanotubes according to the second aspect of the present application, and the description thereof will not be repeated. .

A third aspect of the present application provides an organic material / carbon nanotube composite comprising a non-covalent functionalized carbon nanotube according to the second aspect of the present application dispersed in an organic material.

The contents described with respect to the first and second aspects of the present application may be applied to the non-covalent functionalized carbon nanotubes according to the third aspect of the present application, and the descriptions thereof are omitted for convenience.

According to one embodiment of the present application, the organic material may be semiconducting or conductive, but is not limited thereto. For example, the organic material may include a semiconductor organic compound, a semiconductor polymer, or a conductive polymer, but is not limited thereto.

For example, the semiconducting organic material is pentacene, tetracene, anthracene, naphthalene, alpha-6-thiophene, alpha-4 -Thiophene (α-4-thiopene), perylene and its derivatives, rubrene and its derivatives, coronene and its derivatives, perylene tetracarboxylic diimide ) And its derivatives, perylene tetracarboxylic dianhydride and its derivatives, poly (3-hexiophene) (P3HT) and its derivatives, polyparaperylenevinylene and its derivatives, polyfluorene And derivatives thereof, polyparaphenylene and derivatives thereof, oligoacenes of naphthalene and derivatives thereof, oligoacenes of alpha-5-thiophene and derivatives thereof, pyromellitic dianhydride and Derivatives thereof, pyromellitic diimides and derivatives thereof, perylene Tracarboxylic dianhydride and its derivatives, phthalocyanine and its derivatives, naphthalene tetracarboxylic diimide and its derivatives, naphthalene tetracarboxylic dianhydride and its derivatives It may include, but is not limited to, at least one selected from a derivative, a conjugated polymer derivative including a substituted or unsubstituted thiophene, and a conjugated polymer derivative including a substituted fluorene. It doesn't happen.

For example, the conductive organic material may include a conductive polymer such as polythiophene or polyvinylidene fluoride, but is not limited thereto.

According to the exemplary embodiment of the present disclosure, the content of the non-covalent functionalized carbon nanotube may be about 0.1 wt% to about 30 wt% based on the total weight of the organic material / carbon nanotube composite, but is not limited thereto.

The polymer may be a conductive polymer such as polythiophene or polyvinylidene fluoride, but is not limited thereto. In this case, the composite may be applied to a photoactive layer or an organic thin film transistor (TFT) of an organic solar cell. The non-covalent functionalized carbon nanotubes may be included in an amount of about 0.1 wt% to about 30 wt%. When the weight% is less, the effect of strengthening the electrical properties is hardly exhibited, and when the weight% is exceeded, the electrical conductivity no longer increases significantly and dispersibility may be reduced.

A fourth aspect of the present application provides an organic thin film transistor comprising the organic material / carbon nanotube composite according to the third aspect of the present application as a semiconductor channel layer.

All of the contents described for the first to third aspects of the present application may be applied to the organic thin film transistor according to the fourth aspect of the present application, and duplicate descriptions are omitted for convenience.

According to the exemplary embodiment of the present application, the organic thin film transistor may include a gate electrode, a gate insulating layer, and an organic material / carbon nanotube composite according to the third aspect of the present invention, the semiconductor channel layer, and the semiconductor channel layer. It may be to include a source electrode and a drain electrode spaced apart from, but is not limited thereto.

According to the exemplary embodiment of the present disclosure, the semiconductor channel layer may be manufactured by applying a solution of the organic material / carbon nanotube composite according to the third aspect of the present application to an organic solvent on the gate insulating layer. The coating method is not particularly limited and may be performed using, for example, spin coating, dip coating, screen printing, or other suitable coating methods.

According to one embodiment of the present application, the organic material / carbon nanotube composite may be one in which the non-covalent functionalized carbon nanotubes are dispersed in the semiconductor organic material described above, but are not limited thereto. For example, as the organic material / carbon nanotube composite, the non-covalent functionalized carbon nanotubes may be dispersed in a semiconducting polymer matrix such as poly (3-hexiophene) (P3HT), but is not limited thereto. no.

For example, the organic material included in the organic material / carbon nanotube composite may include a semiconductor material, but is not limited thereto.

Hereinafter, the technology disclosed herein will be described in more detail with reference to the following examples, but the spirit of the disclosed technology is not limited by the present embodiment.

[ Example ]

Example  One. Reformed PBA ( Pyrene  Butanoic acid)

PBA (pyrene butanoic acid) As shown in the scheme below.

First, 50 mg of PBA (pyrene butanoic acid) and 20 ml of thionyl chloride (SOCl ₂ ) contained in 1 ml of DMF (dimethylformamide) were mixed and stirred at 70 ° C. for 12 hours. The remaining unreacted thionyl chloride was dried at room temperature and in vacuo, then mixed with the solid mixture remaining after drying and 1 g of octadecylamine (ODA), stirred at 100 ° C. for 48 hours, and chloroform (chloroform, Washed several times with CHCl ₃ ). Subsequently, after removing the solvent, a light yellow powder of PBA (m-PBA) modified with the alkyl amine was obtained:

[ Reformed PBA Of carbon nanotubes by Unshared  Functionalization scheme ( scheme )]

Example  2: functionalized carbon nanotubes ( CNT Manufacturing

As shown in the scheme, carbon nanotubes (CNT) were prepared using the modified PBA (m-PBA) prepared in Example 1. Non-covalent functionalization.

First, single walled carbon nanotubes (single walled CNT) manufactured by p-HiPco method (Undym, USA) were added to hydrochloric acid and purified by sonication for 12 hours. After washing with water, the CNTs were then dried under vacuum at 100 ° C. 5 mg of purified and dried CNTs and 50 mg of m-PBA were mixed and sonicated in chloroform for 15 hours. The CNTs were then washed three times with chloroform. Finally, drying in vacuo at 100 ° C. yielded CNTs non-covalently functionalized by m-PBA.

On the other hand, for comparison, covalently functionalized CNTs were prepared as follows. First, 50 mg of purified CNT was added to 100 ml of a mixture of sulfuric acid and nitric acid 3: 1 and sonicated for 3 hours to oxidize. Covalently functionalized CNTs were washed after washing until the pH of the solution reached 7.

Referring to the scheme showing non-covalent functionalization of CNT by m-PBA, the carboxylic acid group of PBA was acylated by thionyl chloride and converted into acyl chloride functional groups. The octadecylamine containing the long alkyl chain was then attached to the acyl group of PBA by nucleophilic acyl substitution. Finally, m-PBA molecules were attached on the CNTs by π-stacking, and successfully non-covalently functionalized CNTs were treated with hydrophobic media (steric hindrance effect) due to the steric hindrance effect of the long alkyl chains attached to the PBA. media).

Example  3: CNT Of P3HT  Complex OTFT Manufacturing

Using CNT / P3HT complex OTFT (Organic Thin Film Transistor) was prepared as follows.

First, a 300 nm thick insulating layer was thermally grown on an n-type silicon substrate. The n-type silicon substrate serves as a gate electrode in the OTFT. The substrate was carefully washed and hexamethyldisilazane (HMDS) was spincoated onto the substrate at 7500 rpm for 35 seconds. 0.5% by weight of P3HT was dissolved in chloroform and m-PBA-CNT was mixed and sonicated for 30 minutes so that m-PBA-CNT was 0.01, 0.1, and 0.25% by weight of P3HT. Prepared. In a glove box filled with nitrogen gas, the mixture was spin coated onto the substrate at 2000 rpm for 60 seconds. Finally, a CNT / P3HT nanocomposite having a thickness of 50 nm was formed on the insulating layer. Gold layers for the source and drain electrodes were formed on the CNT / P3HT nanocomposite with a thickness of 50 nm, which was performed by thermal evaporation in a vacuum chamber using a designed shadow mask. In the OTFT manufactured by the above process, the width W of the channel is 1500 µm and the length L of the channel is 100 µm.

<Analysis>

The FT-IR spectra were recorded by Jasco's FT / IR-4100 type-A spectrometer and the mode of use was attenuated total reflectance (ATR) absorption spectroscopy. UV-Vis spectra were measured in THF solvent using a spectrometer of the UV-3101PC model. The microstructure was analyzed using a scanning electron microscope of Hitachi's S-480 model. High resolution dispersion Raman microscopy results were obtained from electron excitation by using a laser source of 325 nm wavelength, and the instrument was an HR UV / vis / NIR model from LabRAM. Surface resistance was measured using a 4-point probe from AiT's CMT-SR2000 model.

<Analysis Result>

FIG. 2A shows unmodified pyrene, FIG. 2B shows pyrene modified with aliphatic amine, and FIG. 2C shows FT-IR spectrum of carbon nanotubes adsorbed modified pyrene.

3 is a pyrene monomolecule unmodified, a green line is a pyrene monomolecule modified with an aliphatic amine, a black nanowire is a carbon nanotube not functionalized, and a red line is a functionalized pyrene single molecule. The results of ultraviolet-visible absorption spectrum of carbon nanotubes are shown. Referring to Figure 3, it can be observed that the pyrene single molecule having a carboxylic acid functional group is substituted with an aliphatic amide. In addition, it can be observed that the pyrene single molecule having an aliphatic amide group is adsorbed onto the carbon nanotube through non-covalent functionalization.

4A and 4B are scanning electron micrographs of carbon nanotubes functionalized using carbon nanotubes not functionalized in a nonpolar solvent and pyrene single molecules modified with aliphatic amines according to Example 2, respectively. 4A and 4B, it can be observed that the functionalized carbon nanotubes are uniformly dispersed in comparison with the carbon nanotubes not functionalized in the nonpolar solvent.

5 is carbon nanotubes not treated with black lines, and red lines are carbon nanotubes functionalized using pyrene monomolecules modified according to Example 2 as a result of Raman spectroscopy, and blue lines are acid treated as a covalent functionalization method. Is the result of carbon nanotubes. Referring to FIG. 5, I _G / I _D values represent values of 6.385, 5.273, and 2.632, respectively. Through this, it can be seen that the non-covalent functionalized carbon nanotubes are similar to those of which the degree of crystallinity is not functionalized and have higher crystallinity than the covalently functionalized carbon nanotubes.

6A is a structural conceptual diagram of an OTFT prepared according to Example 3;

6B is an output characteristic curve of the manufactured OTFT. When a gate bias voltage (V _GS ) of -40 V was applied, the output characteristics of pure P3HT, 0.25 wt% m-PBA-CNT / P3HT, and raw CNT / P3HT devices were shown. Because of the addition of highly conductive CNTs, the drain current (I _DS ) of the device comprising the CNT composite was higher than that of the device consisting of P3HT alone. In addition, the m-PBA-CNT / P3HT device showed higher I _DS than the raw CNT / P3HT device. Most of these improvements result from m-PBA-CNTs, which exhibit more uniform dispersibility than the raw CNTs at the P3HT matrix. Through the above, it can be seen that the non-covalent functionalized carbon nanotubes / P3HT exhibit a much higher current than the TFTs prepared from the composite of the non-functionalized carbon nanotubes / P3HT and P3HT.

6c is a transmission characteristic curve of the manufactured OTFT. It can be seen that non-covalent functionalized carbon nanotubes / P3HT exhibit much higher currents than OTFTs prepared from composites of unfunctionalized carbon nanotubes / P3HT and P3HT.

Figure 6d shows the charge mobility according to the concentration of carbon nanotubes of the prepared OTFT. As the concentration of carbon nanotubes increases, the charge mobility increases, and it can be seen that the non-covalent functionalized carbon nanotubes / P3HT have a charge mobility up to 15 times higher than that of the unfunctionalized carbon nanotubes / P3HT complex. The average field-effect mobility of each transistor was calculated from the slope in the separation region from the transfer curve of the device when V _DS was -80 V, as shown in FIG. 6D, and the data was plotted in the formula described below. Was fitted by:

Where μ is the carrier mobility, V _T is the threshold voltage, C _i is 10.8 × 10 ⁻⁹ F · cm ² , W is 1500 μm, and L is 100 μm. The raw material CNT / P3HT and m-PBA-CNT devices showed improved field-effect mobility as the concentration of CNT increased. Individually, the field-effect mobility of m-PBA-CNT / P3HT devices containing 0.25% by weight of m-PBA-CNTs in the channel layer increased 1.5 to 10 ^-2 cm ² / approximately 15 times that of pure P3HT devices. V · s. In contrast, as shown in FIG. 6D, the raw material CNT / P3HT device had only 2.4 × 10 ⁻³ cm ² / V · s of field-effect mobility in an experiment conducted under the same conditions. It also reveals that m-PBA-CNTs at the P3HT matrix are more effective in conduction pathways than when the raw CNTs are at the P3HT matrix. However, the mobility of the OTFT device prepared by adding 0.5% by weight of non-covalent functionalized CNT to P3HT showed 6.6 × 10 ⁻³ cm ² / V · s, which was lower than that of 0.25% by weight. This important result stems from the aggregation of CNTs in P3HT due to the limited coverage of m-PBA molecules that CNTs adsorb on CNTs at high concentrations.

In the above, the performance of the OTFT including the non-covalent functionalized CNT was evaluated. In addition, to measure the electrical conductivity of CNT itself, a thin sheet of CNT aggregate was prepared from the equivalent amounts of CNT and m-PBA-CNT, and the electrical conductivity was measured by a four-point probe. Indicated in:

Shared functionalized CNT m-PBA-CNT Electrical conductivity (S / cm) 75.9 809.9

Using the same amount of CNTs, the electrical conductivity of m-PBA-CNTs was 10 times higher than that of co-functionalized CNTs.

In summary, in this example, a new non-covalent functionalization of CNTs is systematically presented by the use of pyrene molecules modified with hydrophobic long alkyl chains. Non-covalent functionalized CNTs were well dispersed in hydrophobic solutions and P3HT sites. By addition of only 0.25% by weight of non-covalent functionalized CNTs to the P3HT matrix, a field effect mobility of 1.5 × 10 ⁻² cm ² / V · s was achieved.

In other words, poly (3-hexiophene) (P3HT) has attracted much attention as a good candidate to replace inorganic semiconductors for flexible electronics because of solution-processability. However, the low charge mobility of P3HT is an obstacle to commercialization. In order to overcome this problem, in this embodiment, a new non-covalent functionalization method of carbon nanotubes (CNT) has been proposed to synthesize CNT / P3HT complex. By using the modification of the pyrene molecules with hydrophobic long alkyl chain molecules, non-covalent functionalized CNTs can be well dispersed in hydrophobic solutions and organic semiconductor substrates. In the preparation of the organic thin film transistor derived from the non-covalent functionalized CNT / organic semiconductor composite according to the present embodiment, the damage to CNTs can be reduced by the non-covalent functionalization method according to the present embodiment, compared to the covalent functionalization by the acid treatment. have. Compared with the OTFT consisting of only P3HT, the OTFT using the non-covalent functionalized CNT / organic semiconductor composite according to the present embodiment shows a 15 times improvement in field effect mobility. This improvement was only achieved by adding 0.25% by weight of said non-covalent functionalized CNT to P3HT.

It will be understood by those of ordinary skill in the art that the foregoing description of the embodiments is for illustrative purposes and that those skilled in the art can easily modify the invention without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single entity may be distributed and implemented, and components described as being distributed may also be implemented in a combined form.

The scope of the present application is indicated by the following claims rather than the above description, and it should be construed that all changes or modifications derived from the meaning and scope of the claims and their equivalents are included in the scope of the present application.

Claims (11)

Reacting the aromatic compound with an aliphatic amine to obtain a lipophilic surface modifier comprising the aromatic compound modified with aliphatic amides;
Treating the lipophilic surface modifier with carbon nanotubes to obtain a non-covalent functionalized carbon nanotube by the lipophilic surface modifier.
A method of producing a non-covalent functionalized carbon nanotube comprising a.
The method of claim 1,
The aromatic compound is a method for producing a non-covalent functionalized carbon nanotube containing a carboxyl functional group.
The method of claim 1,
The aromatic compound is selected from the group consisting of pyrene-based compound, porphyrin-based compound and combinations thereof, a method for producing a non-covalent functionalized carbon nanotube.
The method of claim 1,
The aliphatic amine comprises a primary amine having 6 to 20 carbon atoms, method of producing a non-covalent functionalized carbon nanotube.
The method of claim 1,
Treatment of the lipophilic surface modifier by mixing with carbon nanotubes includes the step of sonicating or stirring the mixture of the lipophilic surface modifier and carbon nanotubes in a solvent. Manufacturing method.
The method of claim 1,
Method for producing a non-covalent functionalized carbon nanotubes, wherein the lipophilic surface modifier is represented by the following formula (1) or (2):
[Formula 1]
Pyrene- (CH ₂ ) _n -CONHR
Where n is 0 to 3,
R is an aliphatic hydrocarbon group having 6 to 20 carbon atoms; or,
(2)
Porphyrin-conhr
Wherein R is an aliphatic hydrocarbon group having 6 to 20 carbon atoms.
A non-covalent functionalized carbon nanotube manufactured by the method according to any one of claims 1 to 6,
The non-covalent functionalized carbon nanotubes, wherein the lipophilic surface modifier is non-covalently functionalized on the surface of the carbon nanotubes.
An organic material / carbon nanotube composite comprising a non-covalent functionalized carbon nanotube according to claim 7 dispersed in an organic material.
The method of claim 8,
The organic material comprises a semiconducting organic compound, semiconducting polymer or conductive polymer, organic material / carbon nanotube composite.
The method of claim 8,
The content of the non-covalent functionalized carbon nanotubes, based on the total weight of the organic material / carbon nanotube composite is 0.1% to 30% by weight, organic material / carbon nanotube composite.
An organic thin film transistor comprising the organic material / carbon nanotube composite according to claim 8 as a semiconductor channel layer.

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