CN106219516A - A kind of method that solution left standstill method prepares oriented alignment single armed CNT - Google Patents

Abstract

The invention discloses a method for preparing directional single-walled carbon nanotubes by a static solution method. A substrate with parallel electrodes on the surface is obliquely placed on single-walled carbon nanotubes, deionized water, a surfactant, In the colloidal liquid prepared by mixing organic polymers, due to the size effect of the parallel electrodes on the carbon nanotubes, the carbon nanotubes can be aligned between the parallel electrodes. Compared with the traditional chemical vapor deposition method for preparing vertically aligned carbon nanotubes, the method is simple to operate, prepares horizontally aligned carbon nanotubes, and can be applied in field effect tubes, field emitters and chemical sensors.

Description

A method for preparing single-armed carbon nanotubes with aligned arrangement by static method in solution

technical field

The invention relates to a method for preparing a functional thin film, which belongs to the fields of nano-film materials and nano-devices, and in particular relates to a novel method for preparing directional arrangement single-walled carbon nanotubes by a static solution method.

Background technique

As a new functional material that has attracted the attention of various countries in recent years, carbon nanotube material has the characteristics of good carrier mobility and current transport ability, good mechanical properties, good optical properties and so on. , Field emitters, semiconductor probes, chemical sensors and other devices have good application prospects.

For many years, single-walled carbon nanotubes have been regarded as new materials that can replace silicon-based TFTs due to their good electrical properties and ultra-thin structure. There are two methods for preparing single-walled carbon nanotube TFTs: chemical vapor deposition and solution filtration. In 2009, Chuan Wang et al. prepared a high-performance single-walled carbon nanotube TFT by the solution filtration method. The current density reached 10uA/µm, and the on-off ratio was greater than 10 ⁴ . (Chuan Wang etc Wafer～Scale Fabrication of SeparatedCarbon Nanotube Thin～Film Transistors for Display Applications, Nano Letters, 2009, Vol.9, No.12).

In 2002, S.J Wind et al. prepared single-walled carbon nanotube TFTs by chemical vapor deposition, and the current density reached 2100 uA/um. (S.J Wind etc Vertical scaling of carbon nanotube field～effecttransistors using top gate electrodes, Applied physics Letters, 2002, Vol.80, No.20) However, due to the low density and non-oriented characteristics, its electrical performance cannot meet the application requirements. In order to solve the above problems, Hyunhyub Ko et al. proposed a method to align carbon nanotubes. And when the solution filtration method is used, the polymer solution of carbon nanotubes is fixed in a certain area when forming a film, and the self-assembled film is grown in parallel on the silicon wafer, and then coated on the silicon wafer, the carbon nanotubes will be damaged due to the size The effect is oriented (due to the pitch of the self-assembled film being smaller than the length of the carbon nanotube). (Hyunhyub Ko etc Liquid～CrystallineProcessing of Highly Oriented Carbon Nanotube Arrays for Thin～FilmTransistors, Nano Letters, 2006, Vol.6, No.7) However, since this method obtains an oriented thin film and then coats electrodes, after removing the self-assembled There may be residues in the film, which will affect the structural performance, and it is not easy to determine the oriented carbon nanotube region, the operation is complicated, and it is not easy to make a complete device.

Contents of the invention

The purpose of the present invention is how to overcome the disadvantages of high cost, complicated preparation, low concentration of carbon nanotubes, lack of orientation, and poor electrical properties, etc., to improve the existing carbon nanotube preparation method and simplify the preparation method. Obtain high performance carbon nanotubes.

The technical problem proposed by the present invention is solved like this: provide a kind of method for the preparation of orientation arrangement single-walled carbon nanotube of novel solution standing method, it is characterized in that, has the following steps:

(1) Mix single-walled carbon nanotubes, deionized water, and surfactants evenly to obtain solution 1;

(2) Add an organic polymer to Solution 1, mix well to obtain a black colloidal liquid, namely Solution 2;

(3) Place the substrate with parallel electrodes obliquely in solution 2 to prepare a wet film;

(4) Naturally crystallize the film in step (3) at normal temperature and in an ordinary atmospheric environment to form single-walled carbon nanotube patterns aligned parallel to the substrate;

(5) Photolithography removes excess parts to obtain a complete pattern of aligned carbon nanotubes.

Further, the mass ratio of the single-walled carbon nanotubes to the surfactant is 1:5-10.

Further, the mass ratio of the single-walled carbon nanotubes to the organic polymer is 1:10-20.

Further, the surfactant and the organic polymer can suspend the single-walled carbon nanotubes on the surface of the solution.

The preparation environment is an ordinary indoor environment without inert gas protection, absolute dryness and other requirements.

The surfactant is one of dodecyltrimethylammonium bromide, cetyltrimethylammonium bromide, sodium dodecylbenzenesulfonate, sodium cetylbenzenesulfonate or more, preferably sodium dodecylbenzenesulfonate;

The organic polymer is polypeptide or protein, such as polystyrene sulfonate, polyvinyl alcohol, polyvinylpyrrolidone, etc., preferably polyvinylpyrrolidone.

Further, there is no special requirement on the thickness of the substrate, and an insulating layer of 300-500 nm is arranged above it, and a metal layer of 100-300 nm is arranged on the insulating layer, and parallel electrodes are formed by photolithography on the metal layer.

Preferably, the insulating layer is a SiO ₂ insulating layer, the length of the parallel electrodes is 0.1-5 mm, and the distance between the electrodes is 3-30 µm. The parallel electrode pattern can orient the carbon nanotubes distributed between the electrodes.

Further, in the step (3), the oblique standing means that the substrate is inclined at 3-20° in the petri dish containing solution 2, and the long side of the parallel electrode is at an angle of 3-20° with the horizontal plane, The standing time in the step (3) is 24-72 hours.

Further, the mixing in the step (1) and the step (2) both adopt ultrasonic mixing.

As a preference, the step (1) or step (2) may be combined with magnetic stirring while ultrasonic mixing is used, the temperature of the magnetic stirring in the step (1) is 60-80°C, and the time is 3-6 hours. The temperature of the magnetic stirring in the step (2) is 60-80° C. and the time is 10-30 minutes.

The carbon nanotubes prepared by the method of the present invention have the following advantages:

A. The product has good orientation, stable electrical performance, stable structure, uniformity and smoothness;

B. Make the interdigitated electrodes first, and then use the interdigitated electrodes to orient the carbon nanotubes. The whole process is easy to operate;

C. Normal temperature reaction, and no special requirements for the environment, low equipment requirements, less investment, and low product cost;

D. The reactants are non-toxic and harmless, and will not pollute the environment and affect human health.

Description of drawings

Fig. 1 is a flow chart of the method of the present invention;

Fig. 2 is the directional SEM figure of the single-walled carbon nanotubes between the parallel electrodes of the product obtained in embodiment 1;

Fig. 3 is the non-directional SEM figure of the single-walled carbon nanotubes outside the parallel electrodes of the product obtained in embodiment 1;

Fig. 4 is a schematic diagram (section) of the method of the present invention;

Among them, 1 is the substrate, 2 is the SiO ₂ insulating layer, 3 is the parallel electrodes, and 4 is the aligned single-walled carbon nanotubes.

detailed description

Below in conjunction with embodiment and accompanying drawing, the present invention is described further:

Embodiment 1: A kind of method for preparing single-walled carbon nanotubes of oriented arrangement by solution static method, comprises the following steps:

(1) Take 20 mL of deionized water and put it into a beaker, weigh 15 mg of carbon nanotubes, weigh 100 mg of sodium dodecylbenzenesulfonate and add it to the beaker, put a magnetic rotor in the beaker, put the beaker into a magnetic stirrer, Adjust the temperature to 70°C, the rotational speed to 12rad/s, magnetically stir for 3 hours, and perform ultrasonic mixing at the same time, so that sodium dodecylbenzenesulfonate and carbon nanotubes are uniformly dispersed in deionized water to obtain solution 1;

(2) Take 150 mg of polyvinylpyrrolidone and add it to solution 1, adjust the temperature to 70°C, rotate at 12 rad/s, stir magnetically for 10 minutes, and perform ultrasonic mixing at the same time to obtain a black colloidal liquid, namely solution 2;

(3) The wet film was prepared by the solution standing method, and the substrate with parallel electrodes was placed in the solution 2 at an angle of 5° to prepare a wet film, and stood for 24 hours to crystallize;

(4) Photolithographically remove excess carbon nanotubes outside the channel to obtain a product.

The product was tested by a field emission scanning electron microscope (SEM), and Figure 2 and Figure 3 were obtained. From the comparison of Figure 2 and Figure 3, it can be seen that the product has good orientation performance, and the structure is uniform, flat and stable.

Embodiment 2: A kind of method for preparing single-walled carbon nanotubes of oriented arrangement by static method of solution, comprises the following steps:

(1) Take 20 mL of deionized water and put it into a beaker, weigh 15 mg of carbon nanotubes, weigh 75 mg of dodecyltrimethylammonium bromide, and add 75 mg of hexadecyltrimethylammonium bromide into the beaker, and ultrasonically Mix to make dodecyltrimethylammonium bromide, cetyltrimethylammonium bromide and carbon nanotubes uniformly dispersed in deionized water to obtain solution 1;

(2) Add 150mg of polystyrene sulfonate and 150mg of polyvinyl alcohol into solution 1, and mix them uniformly with ultrasound to obtain a black colloidal liquid, namely solution 2;

(3) The wet film was prepared by the solution static method, and the substrate with parallel electrodes was placed in the solution 2 at an angle of 2° to prepare a wet film, and it was crystallized after standing for 72 hours;

(4) Photolithographically remove excess carbon nanotubes outside the channel to obtain a product.

Embodiment 3: A kind of method for preparing single-walled carbon nanotubes of oriented arrangement by solution static method, comprises the following steps:

(1) Take 20 mL of deionized water and put it into a beaker, weigh 15 mg of carbon nanotubes, weigh 40 mg of cetyltrimethylammonium bromide, and add 60 mg of sodium dodecylbenzenesulfonate into the beaker. Insert the magnetic rotor, put the beaker into a magnetic stirrer, adjust the temperature to 80°C, and the rotation speed to 12rad/s, and magnetically stir for 5 hours, while ultrasonically mixing, so that sodium dodecylbenzenesulfonate and carbon nanotubes are evenly dispersed in the In deionized water, solution 1 was obtained;

(2) Take 200 mg of polyvinyl alcohol and add it to solution 1, adjust the temperature to 80 ° C, rotate at 12 rad/s, stir magnetically for 20 minutes, and perform ultrasonic mixing at the same time to obtain a black colloidal liquid, namely solution 2;

(3) The wet film was prepared by the solution static method, and the substrate with parallel electrodes was placed in the solution 2 at an angle of 30° to prepare a wet film, and it was crystallized after standing for 48 hours;

(4) Photolithographically remove excess carbon nanotubes outside the channel to obtain a product.

Embodiment 4: A kind of method for preparing single-walled carbon nanotubes of oriented arrangement by solution static method, comprises the following steps:

(1) Take 20mL of deionized water and put it into a beaker, weigh 15mg of carbon nanotubes, weigh 75mg of sodium dodecylbenzenesulfonate and add it to the beaker, put a magnetic rotor in the beaker, put the beaker into a magnetic stirrer, Adjust the temperature to 60°C, the rotational speed to 12rad/s, magnetically stir for 6 hours, and perform ultrasonic mixing at the same time, so that sodium dodecylbenzenesulfonate and carbon nanotubes are uniformly dispersed in deionized water to obtain solution 1;

(2) Take 300 mg of protein that can suspend single-walled carbon nanotubes on the surface of the solution and add it to solution 1, adjust the temperature to 60 ° C, rotate at 12 rad/s, stir magnetically for 30 minutes, and perform ultrasonic mixing at the same time to obtain a black colloidal liquid , namely solution 2;

(3) The wet film was prepared by the solution static method, and the substrate with parallel electrodes was placed in the solution 2 at an angle of 5° to prepare a wet film, and it was crystallized after standing for 72 hours;

(4) Photolithographically remove excess carbon nanotubes outside the channel to obtain a product.

Embodiment 5: a method for preparing single-walled carbon nanotubes in an orientation by a solution static method, comprising the following steps:

(1) Take 20 mL of deionized water and put it into a beaker, weigh 15 mg of carbon nanotubes, weigh 80 mg of sodium dodecylbenzene sulfonate, add it to the beaker, and perform ultrasonic mixing to make sodium dodecylbenzene sulfonate and carbon The nanotubes were uniformly dispersed in deionized water to obtain solution 1;

(2) Take 250 mg of polypeptide substances that can suspend single-walled carbon nanotubes on the surface of the solution, add them to solution 1, and perform ultrasonic mixing to obtain a black colloidal liquid, namely solution 2;

(3) The wet film was prepared by the solution static method, and the substrate with parallel electrodes was placed in the solution 2 at an angle of 12° to prepare a wet film, and it was crystallized after standing for 36 hours;

(4) Photolithographically remove excess carbon nanotubes outside the channel to obtain a product.

As mentioned above, it is only a preferred embodiment of the present invention, so any simple changes, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention without departing from the technical content of the present solution still belong to the present invention. The scope of the technical solution of the invention.

Claims (10)

1. a method for preparing directional arrangement single-walled carbon nanotubes by a solution static method, is characterized in that, comprises the following steps: (1) Mix single-walled carbon nanotubes, deionized water, and surfactants evenly to obtain solution 1; (2) Add an organic polymer to Solution 1, mix well to obtain a black colloidal liquid, namely Solution 2; (3) Place the substrate with parallel electrodes obliquely in solution 2 to prepare a wet film; (4) Naturally crystallize the film in step (3) at normal temperature and in an ordinary atmospheric environment to form single-walled carbon nanotube patterns aligned parallel to the substrate; (5) Photolithography removes excess parts to obtain a complete pattern of aligned carbon nanotubes. 2. a kind of solution standing method according to claim 1 prepares the method for directional arrangement single-walled carbon nanotubes, it is characterized in that: the mass ratio of single-walled carbon nanotubes and tensio-active agent in described step (1) 1:5-10. 3. a kind of solution standing method according to claim 1 prepares the method for directional arrangement single-walled carbon nanotubes, it is characterized in that: in described step (2), single-walled carbon nanotubes and organic polymer mass ratio are 1:10-20. 4. according to claim 1, 2, the method for preparing single-walled carbon nanotubes of oriented arrangement by a kind of solution static method described in claim 3, it is characterized in that: described tensio-active agent and organic polymer can allow single-walled carbon nanotubes Walled carbon nanotubes float on the surface of the solution. 5. a kind of solution standing method according to claim 4 prepares the method for directional arrangement single-walled carbon nanotubes, it is characterized in that: described tensio-active agent is dodecyl trimethyl ammonium bromide, ten One or more of hexaalkyltrimethylammonium bromide, sodium dodecylbenzenesulfonate, and sodium cetylbenzenesulfonate, preferably sodium dodecylbenzenesulfonate; the organic The polymers are polypeptides or proteins, preferably polyvinylpyrrolidone. 6. The method for preparing directional single-walled carbon nanotubes by a solution static method according to claim 1, characterized in that: an insulating layer of 300-500 nm is arranged above the substrate, and an insulating layer of 300-500 nm is arranged on the insulating layer. There is a metal layer of 100-300nm, and the metal layer is photoetched with parallel electrode patterns. 7. a kind of solution standing method according to claim 6 prepares the method for directional arrangement single-walled carbon nanotubes, it is characterized in that: described insulating layer is SiO ₂ insulating layer, described parallel electrode length is 0.1 ～5mm, the distance between electrodes is 3～30 μm. 8. The method for preparing directional single-walled carbon nanotubes by a solution static method according to claim 1, characterized in that: in the step (3), the oblique static means that the substrate will be placed in a 3-3 20° inclined in the petri dish containing solution 2, and make the long side of the parallel electrodes form an angle of 3-20° with the horizontal plane, and the standing time is 24-72 hours. 9. A method for preparing directional single-walled carbon nanotubes by a solution static method according to claim 1, characterized in that: the mixing in the step (1) and the step (2) adopts ultrasonic mixing. 10. A method for preparing single-walled carbon nanotubes in an orientation by a static solution method according to claim 1, characterized in that: the step (1) or step (2) can be combined with ultrasonic mixing There is magnetic stirring, the magnetic stirring temperature in the step (1) is 60-80°C, and the time is 3-6 hours; the magnetic stirring temperature in the step (2) is 60-80°C, and the time is 10-30min .