A single-handed carbon nanotube array film based on dielectrophoresis method, a preparation method and application thereof

Abstract

A single-chirality carbon nanotube array film based on dielectrophoresis method, a preparation method and application thereof, the preparation method comprising: preparing a high-purity single-chirality carbon nanotube solution; preparing an electrophoresis electrode structure, the electrophoresis electrode structure comprising a substrate, a plurality of electrophoresis electrodes being etched on the substrate, and a plurality of devices being etched between adjacent electrophoresis electrodes; connecting a sinusoidal voltage source to the electrophoresis electrodes, and adding the high-purity single-chirality carbon nanotube solution into the gap between the electrophoresis electrodes for electrophoresis, so that the single-chirality carbon nanotubes are arranged in an array in the channel of the device; after the electrophoresis, the substrate surface is cleaned and dried to obtain a single-chirality carbon nanotube array film distributed in the channel of the device of the electrophoresis electrode structure; the prepared single-chirality carbon nanotube array film can be applied to the fields of electronics, optoelectronics and energy, and can be used to prepare radio frequency devices, optoelectronic devices and energy storage devices; the present application improves the preparation efficiency and controllability of the carbon nanotube array film, and has the characteristics of high raw material utilization rate and simple operation.

Description

Technical Field

[0001] This invention relates to the field of carbon-based integrated circuit technology, specifically to a single-chiral carbon nanotube array thin film based on dielectric electrophoresis, its preparation method, and its application. Background Technology

[0002] Semiconducting single-walled carbon nanotubes (s-SWCNTs) have emerged as a strong candidate for novel semiconductor materials in the post-Moore's Law era due to their superior electrical properties, such as high carrier mobility and ballistic transport. However, the chiral diversity of s-SWCNTs leads to performance fluctuations in s-SWCNT-based field-effect transistors (CNT-FETs), thus limiting the application of s-SWCNT carbon-based electronics in high-end ICs. With the in-depth research on carbon-based materials and the advancement of micro- and nanoelectronic technologies, single-chiral carbon nanotubes have attracted considerable attention. Single-chiral s-SWCNTs possess excellent electrical properties, controllable structure, and uniformity. Because their structure contains only one rotational arrangement of carbon atoms, single-chiral carbon nanotubes exhibit superior optical, electronic, and mechanical properties, thus showing broad application prospects in the field of nanotechnology. However, current single-chiral carbon nanotube preparation processes are not mature enough. Scientists are conducting increasingly in-depth research on single-chiral s-SWCNTs, but there are still many problems to be solved in chiral sorting and thin film preparation based on single-chiral s-SWCNTs. For example, screening methods suffer from serious waste of raw materials and solvents, high costs, and great screening difficulty.

[0003] Furthermore, overcoming the challenges of high-density arrangement and precise placement of single-chiral arrays of carbon nanotubes is an important topic in current research on carbon-based integrated circuits.

[0004] Patent application CN110993793A discloses a method for preparing a quasi-array thin film of semiconducting carbon nanotubes. The method includes: taking semiconducting carbon nanotubes and dissolving them in a volatile organic solvent to obtain a semiconducting carbon nanotube solution; taking a substrate, cleaning and drying it, and then vertically immersing it in deionized water, leaving only a portion sufficient to hold the substrate above the water surface, thus forming a three-phase interface at the junction of the substrate, deionized water, and air; continuously supplying droplets or sprays of the semiconducting carbon nanotube solution to the three-phase interface and vertically pulling the substrate out of the deionized water; cleaning the substrate and drying it with high-purity gas to obtain a quasi-array thin film of semiconducting carbon nanotubes. However, this array preparation method is inefficient, and the pulling method requires a large volume of solution, resulting in material waste and limiting its application in the early stages of carbon-based integrated circuit exploration.

[0005] Patent application CN 111232954A discloses a high-purity, high-concentration chiral carbon nanotube dispersion, carbon nanotube films, and their preparation method. The preparation method includes: dispersing chiral single-walled carbon nanotube raw materials in a first organic solvent containing a polymer dispersant to form a chiral single-walled carbon nanotube stock solution; centrifuging the solution and collecting the supernatant; concentrating the supernatant to obtain a concentrated solution; subjecting the concentrated solution to ultra-high-speed centrifugation and separating the chiral single-walled carbon nanotube precipitate; washing the precipitate and dispersing it in a second organic solvent to obtain a high-purity, high-concentration chiral single-walled carbon nanotube dispersion. This application also discloses a method for preparing high-quality single-chiral single-walled carbon nanotube films using the aforementioned high-purity, high-concentration chiral single-walled carbon nanotube dispersion. These results provide important information for a better understanding of the mechanism of polymer encapsulation and for improving the extraction of single-chiral sSWCNTs.

[0006] Lianmao Peng's team proposed a closed-loop recycling strategy for separating s-SWCNTs (High-yield and low-cost separation of high-purity semiconducting single-walled carbon nanotubes with closed-loop recycling of raw materials and solvents). In this method, the raw materials for carbon nanotubes and polymers, as well as the solvents, are recovered and reused. After multiple cycles and separations, high semiconductor purity and structural quality are maintained after each cycle. Specifically, the raw materials of CNTs and conjugated polymers (PCz) are mixed in toluene. After dispersing the source materials, the suspension is centrifuged (and undispersed CNTs precipitate to the bottom of the centrifuge tube). The upper 90% supernatant is collected for further processing, and the sediment is collected for the next cycle of separation. New separation cycles use the supernatant and sediment as raw materials and separate after repeating the above ultrasonic treatment and ultracentrifugation process.

[0007] However, existing technologies have the following drawbacks:

[0008] (1) The Czochralski method has achieved significant results in the preparation of hybrid chiral carbon nanotube array films. However, this method requires a large amount of carbon nanotube solution, which leads to a certain degree of raw material waste. In addition, long-term storage can also cause changes in the properties of the carbon nanotube solution, thereby affecting the preparation effect.

[0009] (2) Hybrid chiral carbon nanotube materials are commonly used in existing array thin film technologies. However, hybrid chiral structures are more complex than monochiral structures, with more complex energy levels. Their conductivity and semiconductor properties change with the chiral ratio, which can affect the performance and stability of carbon-based integrated circuits.

[0010] (3) At present, breaking through the technical process for stable screening of single-chiral carbon nanotubes is a significant challenge. Existing screening technologies require complex operating procedures or specialized equipment, resulting in low screening efficiency. In addition, in the existing screening process for single-chiral carbon nanotubes, excess solvent and most of the carbon nanotubes are usually left in the precipitate and discarded, which leads to a significant increase in cost and is not conducive to practical applications. Summary of the Invention

[0011] To overcome the shortcomings of the prior art, the present invention aims to provide a single-chiral carbon nanotube array film based on dielectric electrophoresis, its preparation method, and its application. High-purity single-chiral carbon nanotube solutions are obtained using polymer screening, and sorting costs are reduced by recycling the precipitate and solvent. Subsequently, on a substrate for preparing the electrophoretic electrode, a photolithography process is used to achieve a parallel arrangement of source and drain electrodes. The single-chiral carbon nanotube solution is then dropped onto the electrophoretic electrode, and a sinusoidal alternating current is applied to the electrode using a function generator, thereby achieving an array arrangement of carbon nanotubes in the device channel. This solves the problem of high screening costs for single-chiral carbon nanotubes, improves the preparation efficiency and controllability of carbon nanotube array films, and provides a new approach for the application of single-chiral carbon nanotube films in carbon-based integrated circuits. It features high raw material utilization, simple operation, and stable process.

[0012] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0013] A method for preparing a single-chiral carbon nanotube array thin film based on dielectric electrophoresis includes the following steps:

[0014] Step 1: Mix carbon nanotube powder raw material, conjugated polymer and organic solvent, and use polymer encapsulation method to screen single-chiral carbon nanotubes to obtain high-purity single-chiral carbon nanotube solution;

[0015] Step 2, fabrication of electrophoretic electrode structure: an electrophoretic electrode structure is fabricated on substrate 1 using photolithography. The electrophoretic electrode structure includes several electrophoretic electrodes 2 etched on substrate 1 using photolithography. Several devices 3 are etched between adjacent electrophoretic electrodes 2. The device 3 includes a channel 4 etched at the center of its upper surface. A source electrode 5 and a drain electrode 6 are arranged in parallel on both sides of the channel 4. The source electrode 5 and the drain electrode 6 are respectively connected to the electrophoretic electrodes 2 on both sides.

[0016] Step 3: Connect the sinusoidal voltage source to the electrophoresis electrode 2 prepared in step 2, and drop the high-purity monochiral carbon nanotube solution prepared in step 1 into the gap between the electrophoresis electrodes. Adjust the peak voltage and frequency of the sinusoidal voltage, and control the electrophoresis duration so that the monochiral carbon nanotubes in the monochiral carbon nanotube solution are arranged in an array in the channel 4 of the device 3.

[0017] Step 4: After electrophoresis, the carbon nanotube solution remaining from Step 3 is driven away from the surface of substrate 1. The surface of substrate 1 is cleaned with propanol and rinsed with deionized water and then dried to obtain a single-chiral carbon nanotube array film distributed in the channel 4.

[0018] The specific process of screening single-chiral carbon nanotubes using the polymer encapsulation method in step 1 is as follows:

[0019] Step 1.1: Mix carbon nanotube powder raw material, conjugated polymer and organic solvent, and disperse them to obtain a uniformly dispersed oily dispersion; by mass ratio, carbon nanotube powder raw material: conjugated polymer: organic solvent = (1~4): (1~4): (1~10);

[0020] Step 1.2: The oily dispersion obtained in Step 1.1 is pre-centrifuged to obtain supernatant and precipitate. The supernatant is then taken and centrifuged again at high speed to obtain a high-purity monochiral carbon nanotube solution.

[0021] In step 1.2, the pre-centrifugation is performed with a rotational centrifugal force of 5000g to 30000g, a time of 20min to 90min, and a temperature of 0℃ to 20℃; the secondary high-speed centrifugation is performed with a rotational centrifugal force of 30000g to 70000g, a time of 0.5h to 20h, and a temperature of 0℃ to 20℃.

[0022] The precipitate obtained after pre-centrifugation in step 1.2 can be cyclically screened. Specifically, a conjugated polymer and an organic solvent are added to the precipitate, and the mixture is thoroughly mixed. The monochiral carbon nanotube solution is then cyclically separated and screened multiple times. The high-purity monochiral carbon nanotube solution obtained from each cycle can be used for the preparation of monochiral carbon nanotube array films in subsequent steps, until monochiral carbon nanotubes can no longer be screened from the precipitate.

[0023] The conjugated polymer in step 1 is preferably one of poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt(6,6′-{2,2′-bipyridine})] (PFO-BPy), poly[(9,9-di-n-octylfluorenyl-2,7-diyl)-alt-(benzo[2,1,3]thiadiazole-4,8-diyl)] (F8BT), poly(9,9-dioctyl-fluorenyl-2,7-diyl-pyridine-2,6-diyl) (PFP), (1-octanoyl)-9H-carbazole-2,7-diyl-alt-pyridine-2,6-diyl) (PCP), and poly(9,9-di-n-octylfluorenyl-2,7-diyl) (PFO).

[0024] The organic solvent used in step 1 is preferably one of toluene, xylene, or chloroform.

[0025] The dispersion process in step 1.1 can be performed using an ultrasonic disruptor or a shear mixer.

[0026] In step 3, the peak voltage of the sinusoidal voltage is 0.1V to 100V, the frequency is 10Hz to 1MHz, and the electrophoresis duration is 2s to 180s. The selection of the electrophoresis duration must ensure that the high-purity monochiral carbon nanotube solution dropped into the gap between the electrophoresis electrodes is not completely evaporated.

[0027] A single-chiral carbon nanotube array thin film based on dielectric electrophoresis is prepared by any of the methods described above.

[0028] An application of a single-chiral carbon nanotube array thin film based on dielectric electrophoresis is proposed for use in the fields of electronics, optoelectronics and energy, and can be used to fabricate radio frequency devices, optoelectronic devices and energy storage devices.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] 1. In step 1 of this invention, the raw materials can be recycled to continue the sorting of the single-chiral carbon nanotube solution. Compared with the prior art, this reduces the cost of raw materials and simplifies the sorting steps to a certain extent.

[0031] 2. In step 1 of this invention, a polymer encapsulation method and a two-stage centrifugation process are used to screen the single-chiral carbon nanotube solution. Compared with the prior art, this method can effectively recover raw materials and efficiently prepare the required high-purity single-chiral carbon nanotube solution. It features simple operation and stable process.

[0032] 3. The electrophoretic electrode structure provided in step 2 of this invention can effectively improve the electrophoretic efficiency and accuracy of carbon nanotube array films, and has stability, controllability and high efficiency.

[0033] 4. In step 3 of this invention, a common electrophoresis electrode is prepared to connect the transistors in parallel. Compared with the prior art, this improves the electrophoresis efficiency, does not damage the electrodes directly connected to the transistors, and protects the transistor performance to a certain extent.

[0034] 5. In step 4 of this invention, the array-arranged single-chiral carbon nanotube film is prepared by dielectric electrophoresis. Compared with the prior art, this method can save single-chiral carbon nanotube solution, and the solution can be used immediately without waste. It has the characteristics of high efficiency and cost saving.

[0035] In summary, compared with existing technologies, this invention utilizes polymer screening to obtain high-purity monochiral carbon nanotube solutions and reduces sorting costs by recycling precipitates and solvents. Subsequently, electrophoretic electrodes are fabricated on a silicon wafer using photolithography, achieving a parallel arrangement of source and drain electrodes. The monochiral carbon nanotube solution is then dropped onto the transistor region between the electrophoretic electrodes, and a sinusoidal alternating current is applied to the electrophoretic electrodes using a function generator. This achieves an array arrangement of carbon nanotubes in the device channel, solving the problem of high screening costs for monochiral carbon nanotubes, improving the fabrication efficiency and controllability of carbon nanotube array films, and providing a new approach for the application of monochiral carbon nanotube films in carbon-based integrated circuits. Attached Figure Description

[0036] Figure 1 This is a flowchart of the method of the present invention.

[0037] Figure 2 This is a schematic diagram showing the connection between the electrophoresis electrode structure and the function generator.

[0038] Figure 3 This is a schematic diagram of the electrophoresis electrode structure.

[0039] Figure 4 This is a magnified schematic diagram of the electrophoresis electrode structure.

[0040] Figure 5 This is a magnified schematic diagram of the device.

[0041] Among them, 1. substrate, 2. electrophoretic electrode, 3. device, 4. channel, 5. source electrode, and 6. drain electrode. Detailed Implementation

[0042] The present invention will now be described in detail with reference to the accompanying drawings.

[0043] A method for preparing a single-chiral carbon nanotube array thin film based on dielectric electrophoresis includes the following steps:

[0044] Step 1: Mix carbon nanotube powder raw material, conjugated polymer and organic solvent, and use polymer encapsulation method to screen single-chiral carbon nanotubes to obtain high-purity single-chiral carbon nanotube solution;

[0045] The conjugated polymer in step 1 is preferably one of poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt(6,6′-{2,2′-bipyridine})] (PFO-BPy), poly[(9,9-di-n-octylfluorenyl-2,7-diyl)-alt-(benzo[2,1,3]thiadiazole-4,8-diyl)] (F8BT), poly(9,9-dioctyl-fluorenyl-2,7-diyl-pyridine-2,6-diyl) (PFP), (1-octanoyl)-9H-carbazole-2,7-diyl-alt-pyridine-2,6-diyl) (PCP), and poly(9,9-di-n-octylfluorenyl-2,7-diyl) (PFO).

[0046] The organic solvent used in step 1 is preferably one of toluene, xylene, or chloroform.

[0047] The specific process of screening single-chiral carbon nanotubes using the polymer encapsulation method in step 1 is as follows:

[0048] Step 1.1: Mix carbon nanotube powder raw material, conjugated polymer and organic solvent, and disperse them to obtain a uniformly dispersed oily dispersion; by mass ratio, carbon nanotube powder raw material: conjugated polymer: organic solvent = (1~4): (1~4): (1~10);

[0049] Step 1.2: The oily dispersion obtained in Step 1.1 is pre-centrifuged to obtain supernatant and precipitate. The supernatant is then taken and centrifuged again at high speed to obtain a high-purity monochiral carbon nanotube solution.

[0050] The dispersion process in step 1.1 can be performed using an ultrasonic disruptor or a shear mixer.

[0051] In step 1.2, the pre-centrifugation is performed with a rotational centrifugal force of 5000g to 30000g, a time of 20min to 90min, and a temperature of 0℃ to 20℃; the secondary high-speed centrifugation is performed with a rotational centrifugal force of 30000g to 70000g, a time of 0.5h to 20h, and a temperature of 0℃ to 20℃.

[0052] The precipitate obtained after pre-centrifugation in step 1.2 can be cyclically screened. Specifically, a conjugated polymer and an organic solvent are added to the precipitate, and the mixture is thoroughly mixed. The monochiral carbon nanotube solution is then cyclically separated and screened multiple times. The high-purity monochiral carbon nanotube solution obtained from each cycle can be used for the preparation of monochiral carbon nanotube array films in subsequent steps, until monochiral carbon nanotubes can no longer be screened from the precipitate.

[0053] In step 1, the recyclable raw materials can be used to continue the sorting of the single-chiral carbon nanotube solution. Compared with the existing technology, this reduces the cost of raw materials and simplifies the sorting process to some extent.

[0054] Step 2, fabrication of electrophoretic electrode structure: an electrophoretic electrode structure is fabricated on substrate 1 using photolithography. The electrophoretic electrode structure includes several electrophoretic electrodes 2 etched on substrate 1 using photolithography. Several devices 3 are etched between adjacent electrophoretic electrodes 2. The device 3 includes a channel 4 etched at the center of its upper surface. A source electrode 5 and a drain electrode 6 are arranged in parallel on both sides of the channel 4. The source electrode 5 and the drain electrode 6 are respectively connected to the electrophoretic electrodes 2 on both sides.

[0055] In step 2, substrate 1 includes silicon oxide, silicon wafer, sapphire, or a thin film of other materials that have been prepared.

[0056] Step 3: Connect an external function generator to the substrate, connect a sinusoidal voltage source to the electrophoresis electrode 2 prepared in step 2, and drop the high-purity monochiral carbon nanotube solution prepared in step 1 into the gap between the electrophoresis electrodes. Adjust the peak voltage of the sinusoidal voltage to 0.1V to 100V and the frequency to 10Hz to 1MHz, and control the electrophoresis duration by applying current for 2 to 180s, so that the monochiral carbon nanotubes in the monochiral carbon nanotube solution are arranged in an array in the channel 4 of device 3. The selection of the electrophoresis duration should ensure that the high-purity monochiral carbon nanotube solution dropped into the gap between the electrophoresis electrodes is not completely evaporated.

[0057] Step 4: After electrophoresis, nitrogen gas is used to drive the carbon nanotube solution remaining in step 3 away from the surface of substrate 1. The surface of substrate 1 is cleaned with propanol and rinsed with deionized water. Then, substrate 1 is dried to obtain a single-chiral carbon nanotube array film distributed in channel 4.

[0058] The single-chiral carbon nanotubes are one of (6,5)chiral, (7,5)chiral, (8,6)chiral, (12,5), and (10,8), and the solution may contain a small amount of other chiral types.

[0059] In step 1, the conjugated polymers PFO-BPy specifically screened the (6, 5) chirality of the SGi65 carbon nanotube raw material, allowing for trace amounts of other chirality; PFP specifically screened the (10, 8) chirality of the HiPco carbon nanotube raw material, allowing for trace amounts of other chirality; PCP specifically screened the (12, 5) chirality of the HiPco carbon nanotube raw material, allowing for trace amounts of other chirality; and F8BT specifically screened the (10, 5) chirality of the HiPco carbon nanotube raw material, allowing for trace amounts of other chirality.

[0060] A single-chiral carbon nanotube array thin film based on dielectric electrophoresis is prepared by any of the methods described above.

[0061] An application of a single-chiral carbon nanotube array thin film based on dielectric electrophoresis is proposed for use in the fields of electronics, optoelectronics and energy, and can be used to fabricate radio frequency devices, optoelectronic devices and energy storage devices.

[0062] The present invention will be further described below with reference to embodiments.

[0063] Example 1

[0064] A method for preparing a single-chiral carbon nanotube array thin film based on dielectric electrophoresis includes the following steps:

[0065] Step 1: Mix SGi65 carbon nanotube powder raw material, poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt(6,6′-{2,2′-bipyridine})](PFO-BPy) and toluene, and use the polymer encapsulation method to screen for single-chiral carbon nanotubes to obtain a high-purity single-chiral carbon nanotube solution.

[0066] The specific process of screening single-chiral carbon nanotubes using the polymer encapsulation method in step 1 is as follows:

[0067] Step 1.1: Mix SGi65 carbon nanotube powder, poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt(6,6′-{2,2′-bipyridine})](PFO-BPy), and toluene, and disperse the mixture using an ultrasonic homogenizer to obtain a uniformly dispersed oily dispersion; by mass ratio, SGi65 carbon nanotube powder: poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt(6,6′-{2,2′-bipyridine})](PFO-BPy): toluene = 1:2:4;

[0068] Step 1.2: The oily dispersion obtained in Step 1.1 is pre-centrifuged to obtain supernatant and precipitate. Then, 20% of the supernatant is taken and centrifuged again at high speed to obtain a high-purity (6,5) monochiral carbon nanotube solution.

[0069] In step 1.2, the pre-centrifugation is performed with a rotational centrifugal force of 10,000g, a time of 20 minutes, and a temperature of 4°C; the secondary high-speed centrifugation is performed with a rotational centrifugal force of 50,000g, a time of 1 hour, and a temperature of 4°C.

[0070] The precipitate obtained after pre-centrifugation in step 1.2 can be cyclically screened. Specifically, poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt(6,6′-{2,2′-bipyridine})](PFO-BPy) and toluene are added to the precipitate, and the mixture is thoroughly mixed. The monochiral carbon nanotube solution is then cyclically separated and screened multiple times. The high-purity monochiral carbon nanotube solution obtained from each cycle can be used for the preparation of monochiral carbon nanotube array films in subsequent steps until the precipitate can no longer screen out monochiral carbon nanotubes.

[0071] Step 2, prepare the electrophoretic electrode structure: prepare the electrophoretic electrode structure on silicon oxide using photolithography. The electrophoretic electrode structure includes several electrophoretic electrodes (2) etched on silicon oxide using photolithography. Several devices 3 are etched between adjacent electrophoretic electrodes 2. The device 3 includes a channel 4 etched at the center of the upper surface. On both sides of the channel 4, a source electrode 5 and a drain electrode 6 are arranged in parallel. The source electrode 5 and the drain electrode 6 are respectively connected to the electrophoretic electrodes 2 on both sides.

[0072] Step 3: Connect an external function generator to the substrate, connect a sinusoidal voltage source to the electrophoresis electrode 2 prepared in step 2, and drop the high-purity monochiral carbon nanotube solution prepared in step 1 into the gap between the electrophoresis electrodes. Adjust the peak voltage of the sinusoidal voltage to 1V and the frequency to 10Hz, and control the electrophoresis time. Apply power for 10s to make the monochiral carbon nanotubes in the monochiral carbon nanotube solution arranged in an array in the channel 4 of the device 3.

[0073] Step 4: After electrophoresis, nitrogen gas is used to blow away the carbon nanotube solution remaining from the silicon oxide surface in step 3. The silicon oxide surface is then cleaned with propanol, rinsed with deionized water, and dried with nitrogen gas to obtain a single-chiral carbon nanotube array film distributed in channel 4.

[0074] A single-chiral carbon nanotube array thin film based on dielectric electrophoresis is prepared by any of the methods described above.

[0075] An application of a single-chiral carbon nanotube array thin film based on dielectric electrophoresis is proposed for use in the fields of electronics, optoelectronics and energy, and can be used to fabricate radio frequency devices, optoelectronic devices and energy storage devices.

[0076] SEM testing showed that the single-chiral carbon nanotube array film prepared in this embodiment exhibits a directional arrangement trend of single-chiral carbon nanotubes in the channel. The single-chiral carbon nanotube array film can be used to further prepare field-effect transistors, providing a new way to improve device performance. This invention has the characteristics of high raw material utilization, simple operation, and stable process.

[0077] Example 2

[0078] A method for preparing a single-chiral carbon nanotube array thin film based on dielectric electrophoresis includes the following steps:

[0079] Step 1: Mix HiPco carbon nanotube powder, poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt(1,4-benzo-{2,1′-3}-thiadiazole)](F8BT) and xylene, and use the polymer encapsulation method to screen for monochiral carbon nanotubes to obtain a high-purity monochiral carbon nanotube solution;

[0080] The specific process of screening single-chiral carbon nanotubes using the polymer encapsulation method in step 1 is as follows:

[0081] Step 1.1: Mix HiPco carbon nanotube powder, poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt(1,4-benzo-{2,1′-3}-thiadiazole)](F8BT), and xylene, and disperse the mixture using a shear mixer to obtain a uniformly dispersed oily dispersion; by mass ratio, HiPco carbon nanotube powder: poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt(1,4-benzo-{2,1′-3}-thiadiazole)](F8BT): xylene = 1:1:2;

[0082] Step 1.2: The oily dispersion obtained in Step 1.1 is pre-centrifuged to obtain supernatant and precipitate. Then, 50% of the supernatant is taken and centrifuged again at high speed to obtain a high-purity (10,5) monochiral carbon nanotube solution.

[0083] In step 1.2, the pre-centrifugation is performed with a rotational centrifugal force of 10,000g, a time of 40 minutes, and a temperature of 5°C; the secondary high-speed centrifugation is performed with a rotational centrifugal force of 40,000g, a time of 2 hours, and a temperature of 10°C.

[0084] The precipitate obtained after pre-centrifugation in step 1.2 can be cyclically screened. Specifically, poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt(1,4-benzo-{2,1′-3}-thiadiazole)](F8BT) and xylene are added to the precipitate, and the mixture is thoroughly mixed. The monochiral carbon nanotube solution is then cyclically separated and screened multiple times. The high-purity monochiral carbon nanotube solution obtained from each cycle can be used for the preparation of monochiral carbon nanotube array films in subsequent steps until the precipitate can no longer screen out monochiral carbon nanotubes.

[0085] Step 2, fabrication of electrophoretic electrode structure: An electrophoretic electrode structure is fabricated on a silicon wafer using photolithography. The electrophoretic electrode structure includes several electrophoretic electrodes 2 etched on the silicon wafer using photolithography. Several devices 3 are etched between adjacent electrophoretic electrodes 2. The device 3 includes a channel 4 etched at the center of its upper surface. A source electrode 5 and a drain electrode 6 are arranged in parallel on both sides of the channel 4. The source electrode 5 and the drain electrode 6 are respectively connected to the electrophoretic electrodes 2 on both sides.

[0086] Step 3: Connect an external function generator to the substrate, connect a sinusoidal voltage source to the electrophoresis electrode 2 prepared in step 2, and drop the high-purity monochiral carbon nanotube solution prepared in step 1 into the gap between the electrophoresis electrodes. Adjust the peak voltage of the sinusoidal voltage to 30V and the frequency to 30Hz, and control the electrophoresis time. Apply power for 100s to make the monochiral carbon nanotubes in the monochiral carbon nanotube solution arranged in an array in the channel 4 of the device 3.

[0087] Step 4: After electrophoresis, nitrogen gas is used to blow away the carbon nanotube solution remaining from Step 3 from the silicon wafer surface. The silicon wafer surface is then cleaned with propanol, rinsed with deionized water, and dried with nitrogen gas to obtain a single-chiral carbon nanotube array film distributed in channel 4.

[0088] A single-chiral carbon nanotube array thin film based on dielectric electrophoresis is prepared by any of the methods described above.

[0089] An application of a single-chiral carbon nanotube array thin film based on dielectric electrophoresis is proposed for use in the fields of electronics, optoelectronics and energy, and can be used to fabricate radio frequency devices, optoelectronic devices and energy storage devices.

[0090] The above-mentioned single-chiral carbon nanotube array thin film can be used to further prepare field-effect transistors, providing a new way to improve device performance. This invention has the characteristics of high raw material utilization, simple operation, and stable process.

[0091] Example 3

[0092] A method for preparing a single-chiral carbon nanotube array thin film based on dielectric electrophoresis includes the following steps:

[0093] Step 1: Mix HiPco carbon nanotube powder, poly(9,9-dioctylfluorene-2,7-diyl-pyridine-2,6-diyl) (PFP) and chloroform, and use the polymer encapsulation method to screen for single-chiral carbon nanotubes to obtain a high-purity single-chiral carbon nanotube solution.

[0094] The specific process of screening single-chiral carbon nanotubes using the polymer encapsulation method in step 1 is as follows:

[0095] Step 1.1: Mix HiPco carbon nanotube powder, poly(9,9-dioctylfluorene-2,7-diyl-pyridine-2,6-diyl) (PFP), and chloroform, and disperse the mixture using an ultrasonic homogenizer to obtain a uniformly dispersed oily dispersion; by mass ratio, HiPco carbon nanotube powder: poly(9,9-dioctylfluorene-2,7-diyl-pyridine-2,6-diyl) (PFP): chloroform = 4:4:10;

[0096] Step 1.2: The oily dispersion obtained in Step 1.1 is pre-centrifuged to obtain supernatant and precipitate. Then, 55% of the supernatant is taken. The 55% supernatant is centrifuged again at high speed to obtain a high-purity (10,8) monochiral carbon nanotube solution.

[0097] In step 1.2, the pre-centrifugation is performed with a rotational centrifugal force of 20,000 g, a time of 55 min, and a temperature of 5 °C; the secondary high-speed centrifugation is performed with a rotational centrifugal force of 50,000 g, a time of 4 h, and a temperature of 5 °C.

[0098] The precipitate obtained after pre-centrifugation in step 1.2 can be cyclically screened. Specifically, poly(9,9-dioctylfluorene-2,7-diyl-pyridine-2,6-diyl) (PFP) and chloroform are added to the precipitate, and the mixture is thoroughly mixed. The monochiral carbon nanotube solution is then cyclically separated and screened multiple times. The high-purity monochiral carbon nanotube solution obtained from each cycle can be used for the preparation of monochiral carbon nanotube array films in subsequent steps until the precipitate can no longer screen out monochiral carbon nanotubes.

[0099] Step 2, fabrication of electrophoretic electrode structure: An electrophoretic electrode structure is fabricated on sapphire using photolithography. The electrophoretic electrode structure includes several electrophoretic electrodes 2 etched on the sapphire using photolithography. Several devices 3 are etched between adjacent electrophoretic electrodes 2. The device 3 includes a channel 4 etched at the center of its upper surface. A source electrode 5 and a drain electrode 6 are arranged in parallel on both sides of the channel 4. The source electrode 5 and the drain electrode 6 are respectively connected to the electrophoretic electrodes 2 on both sides.

[0100] Step 3: Connect an external function generator to the substrate, connect a sinusoidal voltage source to the electrophoresis electrode 2 prepared in step 2, and drop the high-purity monochiral carbon nanotube solution prepared in step 1 into the gap between the electrophoresis electrodes. Adjust the peak voltage of the sinusoidal voltage to 20V and the frequency to 55Hz, and control the electrophoresis time. Apply power for 90s to make the monochiral carbon nanotubes in the monochiral carbon nanotube solution arranged in an array in the channel 4 of the device 3.

[0101] Step 4: After electrophoresis, nitrogen gas is used to blow away the carbon nanotube solution remaining from step 3 from the sapphire surface. The sapphire surface is then cleaned with propanol, rinsed with deionized water, and dried with nitrogen gas to obtain a single-chiral carbon nanotube array film distributed in channel 4.

[0102] A single-chiral carbon nanotube array thin film based on dielectric electrophoresis is prepared by any of the methods described above.

[0103] An application of a single-chiral carbon nanotube array thin film based on dielectric electrophoresis is proposed for use in the fields of electronics, optoelectronics and energy, and can be used to fabricate radio frequency devices, optoelectronic devices and energy storage devices.

[0104] The above-mentioned single-chiral carbon nanotube array thin film can be used to further prepare field-effect transistors, providing a new way to improve device performance. This invention has the characteristics of high raw material utilization, simple operation, and stable process.

[0105] Example 4

[0106] A method for preparing a single-chiral carbon nanotube array thin film based on dielectric electrophoresis includes the following steps:

[0107] Step 1: Mix HiPco carbon nanotube powder raw material, (1-octanoyl)-9H-carbazole-2,7-diyl-alt-pyridine-2,6-diyl](PCP) and toluene, and use the polymer encapsulation method to screen for single-chiral carbon nanotubes to obtain a high-purity single-chiral carbon nanotube solution.

[0108] The specific process of screening single-chiral carbon nanotubes using the polymer encapsulation method in step 1 is as follows:

[0109] Step 1.1: Mix HiPco carbon nanotube powder, [(1-octanoyl)-9H-carbazole-2,7-diyl-alt-pyridine-2,6-diyl](PCP) and toluene, and disperse using a shear mixer to obtain a uniformly dispersed oily dispersion; by mass ratio, HiPco carbon nanotube powder: [(1-octanoyl)-9H-carbazole-2,7-diyl-alt-pyridine-2,6-diyl](PCP): toluene = 1:1:1;

[0110] Step 1.2: The oily dispersion obtained in Step 1.1 is pre-centrifuged to obtain supernatant and precipitate. Then, 72.5% of the supernatant is taken. The 72.5% supernatant is centrifuged again at high speed to obtain a high-purity (12,5) monochiral carbon nanotube solution.

[0111] In step 1.2, the pre-centrifugation is performed with a rotational centrifugal force of 20,000 g, a time of 72 min, and a temperature of 7.5 °C; the secondary high-speed centrifugation is performed with a rotational centrifugal force of 60,000 g, a time of 6 h, and a temperature of 7.5 °C.

[0112] The precipitate obtained after pre-centrifugation in step 1.2 can be cyclically screened. Specifically, (1-octanoyl)-9H-carbazole-2,7-diyl-alt-pyridine-2,6-diyl](PCP) and toluene are added to the precipitate, mixed thoroughly, and the monochiral carbon nanotube solution is cyclically separated and screened. The cyclic screening is repeated multiple times. The high-purity monochiral carbon nanotube solution obtained from each cycle screening can be used for the preparation of monochiral carbon nanotube array films in subsequent steps until monochiral carbon nanotubes can no longer be screened from the precipitate.

[0113] Step 2, fabrication of electrophoretic electrode structure: An electrophoretic electrode structure is fabricated on silicon oxide using photolithography. The electrophoretic electrode structure includes several electrophoretic electrodes 2 etched on silicon oxide using photolithography. Several devices 3 are etched between adjacent electrophoretic electrodes 2. The device 3 includes a channel 4 etched at the center of its upper surface. On both sides of the channel 4, a source electrode 5 and a drain electrode 6 are arranged in parallel. The source electrode 5 and the drain electrode 6 are respectively connected to the electrophoretic electrodes 2 on both sides.

[0114] Step 3: Connect an external function generator to the substrate, connect a sinusoidal voltage source to the electrophoresis electrode 2 prepared in step 2, and drop the high-purity monochiral carbon nanotube solution prepared in step 1 into the gap between the electrophoresis electrodes. Adjust the peak voltage of the sinusoidal voltage to 15V and the frequency to 77Hz, and control the electrophoresis time. Apply power for 135s to make the monochiral carbon nanotubes in the monochiral carbon nanotube solution arranged in an array in the channel 4 of the device 3.

[0115] Step 4: After electrophoresis, nitrogen gas is used to blow away the carbon nanotube solution remaining from the silicon oxide surface in step 3. The silicon oxide surface is then cleaned with propanol, rinsed with deionized water, and dried with nitrogen gas to obtain a single-chiral carbon nanotube array film distributed in channel 4.

[0116] A single-chiral carbon nanotube array thin film based on dielectric electrophoresis is prepared by any of the methods described above.

[0117] An application of a single-chiral carbon nanotube array thin film based on dielectric electrophoresis is proposed for use in the fields of electronics, optoelectronics and energy, and can be used to fabricate radio frequency devices, optoelectronic devices and energy storage devices.

[0118] The above-mentioned single-chiral carbon nanotube array thin film can be used to further prepare field-effect transistors, providing a new way to improve device performance. This invention has the characteristics of high raw material utilization, simple operation, and stable process.

[0119] Example 5

[0120] A method for preparing a single-chiral carbon nanotube array thin film based on dielectric electrophoresis includes the following steps:

[0121] Step 1: Mix SGi65 carbon nanotube powder, poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt(6,6′-{2,2′-bipyridine})](PFO-BPy) and xylene, and use the polymer encapsulation method to screen for single-chiral carbon nanotubes to obtain a high-purity single-chiral carbon nanotube solution;

[0122] The specific process of screening single-chiral carbon nanotubes using the polymer encapsulation method in step 1 is as follows:

[0123] Step 1.1: Mix SGi65 carbon nanotube powder, poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt(6,6′-{2,2′-bipyridine})](PFO-BPy), and xylene, and disperse the mixture using an ultrasonic homogenizer to obtain a uniformly dispersed oily dispersion; by mass ratio, SGi65 carbon nanotube powder: poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt(6,6′-{2,2′-bipyridine})](PFO-BPy): xylene = 1:1:4;

[0124] Step 1.2: The oily dispersion obtained in Step 1.1 is pre-centrifuged to obtain supernatant and precipitate. Then, 90% of the supernatant is taken and centrifuged again at high speed to obtain a high-purity (6,5) monochiral carbon nanotube solution.

[0125] In step 1.2, the pre-centrifugation is performed with a rotational centrifugal force of 30,000 g, a time of 90 min, and a temperature of 10 °C; the secondary high-speed centrifugation is performed with a rotational centrifugal force of 70,000 g, a time of 8 h, and a temperature of 10 °C.

[0126] The precipitate obtained after pre-centrifugation in step 1.2 can be cyclically screened. Specifically, poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt(6,6′-{2,2′-bipyridine})](PFO-BPy) and xylene are added to the precipitate, and the mixture is thoroughly mixed. The monochiral carbon nanotube solution is then cyclically separated and screened multiple times. The high-purity monochiral carbon nanotube solution obtained from each cycle can be used for the preparation of monochiral carbon nanotube array films in subsequent steps until the precipitate can no longer screen out monochiral carbon nanotubes.

[0127] Step 2, fabrication of electrophoretic electrode structure: An electrophoretic electrode structure is fabricated on a silicon wafer using photolithography. The electrophoretic electrode structure includes several electrophoretic electrodes 2 etched on the silicon wafer using photolithography. Several devices 3 are etched between adjacent electrophoretic electrodes 2. The device 3 includes a channel 4 etched at the center of its upper surface. A source electrode 5 and a drain electrode 6 are arranged in parallel on both sides of the channel 4. The source electrode 5 and the drain electrode 6 are respectively connected to the electrophoretic electrodes 2 on both sides.

[0128] Step 3: Connect an external function generator to the substrate, connect a sinusoidal voltage source to the electrophoresis electrode 2 prepared in step 2, and drop the high-purity monochiral carbon nanotube solution prepared in step 1 into the gap between the electrophoresis electrodes. Adjust the peak voltage of the sinusoidal voltage to 100V and the frequency to 100Hz, and control the electrophoresis time. Apply power for 180s to make the monochiral carbon nanotubes in the monochiral carbon nanotube solution arranged in an array in the channel 4 of the device 3.

[0129] Step 4: After electrophoresis, nitrogen gas is used to blow away the carbon nanotube solution remaining from Step 3 from the silicon wafer surface. The silicon wafer surface is then cleaned with propanol, rinsed with deionized water, and dried with nitrogen gas to obtain a single-chiral carbon nanotube array film distributed in channel 4.

[0130] A single-chiral carbon nanotube array thin film based on dielectric electrophoresis is prepared by any of the methods described above.

[0131] An application of a single-chiral carbon nanotube array thin film based on dielectric electrophoresis is proposed for use in the fields of electronics, optoelectronics and energy, and can be used to fabricate radio frequency devices, optoelectronic devices and energy storage devices.

[0132] The above-mentioned single-chiral carbon nanotube array thin film can be used to further prepare field-effect transistors, providing a new way to improve device performance. This invention has the characteristics of high raw material utilization, simple operation, and stable process.

[0133] The above descriptions are merely five specific examples of the present invention and do not constitute any limitation on the present invention. Obviously, those skilled in the art, after understanding the content and principles of the present invention, may make various modifications and changes in form and details without departing from the principles and structure of the present invention. For example, in addition to the Si material used in the embodiments of the present invention, the substrate may also use any one of SiO2, GaN, InP, sapphire, etc.

[0134] In summary, this invention proposes to obtain high-purity single-chiral carbon nanotube solutions of different types using a polymer screening method, and reduces the sorting cost by recycling the precipitate and solvent, thus solving the problem of high screening cost for single-chiral carbon nanotubes. After electrophoresis, carbon nanotubes at both ends of the transistor electrode exhibit an array arrangement tendency with good uniformity, a reduced number of carbon nanotube-carbon nanotube junctions, and improved arrangement regularity. Furthermore, the carbon nanotubes arranged near the two electrodes overlap, thereby realizing the array arrangement of carbon nanotubes in the device channel and improving the preparation efficiency and controllability of carbon nanotube array films.

Claims

1. A method for preparing a single-chiral carbon nanotube array thin film based on dielectric electrophoresis, characterized in that, Includes the following steps: Step 1: Mix carbon nanotube powder raw material, conjugated polymer and organic solvent, and use polymer encapsulation method to screen single-chiral carbon nanotubes to obtain high-purity single-chiral carbon nanotube solution; Step 2, fabrication of electrophoretic electrode structure: an electrophoretic electrode structure is fabricated on substrate (1) using photolithography. The electrophoretic electrode structure includes several electrophoretic electrodes (2) etched on substrate (1) using photolithography. Several devices (3) are etched between adjacent electrophoretic electrodes (2). The device (3) includes a channel (4) etched at the center of the upper surface. Active electrodes (5) and drain electrodes (6) are arranged in parallel on both sides of the channel (4). The active electrodes (5) and drain electrodes (6) are connected to the electrophoretic electrodes (2) on both sides respectively. Step 3: Connect the sinusoidal voltage source to the electrophoresis electrode (2) prepared in step 2, and drop the high-purity monochiral carbon nanotube solution prepared in step 1 into the gap between the electrophoresis electrodes. Adjust the peak voltage and frequency of the sinusoidal voltage, and control the electrophoresis duration so that the monochiral carbon nanotubes in the monochiral carbon nanotube solution are arranged in an array in the channel (4) of the device (3). Step 4: After electrophoresis, the carbon nanotube solution remaining from step 3 is driven away from the surface of the substrate (1), the surface of the substrate (1) is cleaned with propanol, and the substrate (1) is dried after rinsing with deionized water to obtain a single-chiral carbon nanotube array film distributed in the channel (4).

2. The method for preparing a single-chiral carbon nanotube array thin film based on dielectric electrophoresis according to claim 1, characterized in that, The specific process of screening single-chiral carbon nanotubes using the polymer encapsulation method in step 1 is as follows: Step 1.1: Mix carbon nanotube powder, conjugated polymer and organic solvent, and disperse them to obtain a uniformly dispersed oily dispersion; by mass ratio, carbon nanotube powder: conjugated polymer: organic solvent = (1~4): (1~4): (1~10); Step 1.2: The oily dispersion obtained in Step 1.1 is pre-centrifuged to obtain supernatant and precipitate. The supernatant is then taken and centrifuged again at high speed to obtain a high-purity monochiral carbon nanotube solution.

3. The method for preparing a single-chiral carbon nanotube array thin film based on dielectric electrophoresis according to claim 2, characterized in that, In step 1.2, the pre-centrifugation is performed with a rotational centrifugal force of 5000g to 30000g, a time of 20min to 90min, and a temperature of 0℃ to 20℃; the secondary high-speed centrifugation is performed with a rotational centrifugal force of 30000g to 70000g, a time of 0.5h to 20h, and a temperature of 0℃ to 20℃.

4. The method for preparing a single-chiral carbon nanotube array thin film based on dielectric electrophoresis according to claim 2, characterized in that, The precipitate obtained after pre-centrifugation in step 1.2 is cyclically screened as follows: a conjugated polymer and an organic solvent are added to the precipitate, mixed thoroughly, and the monochiral carbon nanotube solution is cyclically separated and screened multiple times. The high-purity monochiral carbon nanotube solution obtained from each cycle is used for the preparation of monochiral carbon nanotube array films in subsequent steps, until monochiral carbon nanotubes can no longer be screened from the precipitate.

5. A method for preparing a single-chiral carbon nanotube array thin film based on dielectric electrophoresis according to claim 1, 2, or 4, characterized in that, The conjugated polymer in step 1 is one of poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt(6,6′-{2,2′-bipyridine})] (PFO-BPy), poly[(9,9-di-n-octylfluorenyl-2,7-diyl)-alt-(benzo[2,1,3]thiadiazole-4,8-diyl)] (F8BT), poly(9,9-dioctyl-fluorenyl-2,7-diyl-pyridine-2,6-diyl) (PFP), (1-octanoyl)-9H-carbazole-2,7-diyl-alt-pyridine-2,6-diyl] (PCP), and poly(9,9-di-n-octylfluorenyl-2,7-diyl) (PFO).

6. A method for preparing a single-chiral carbon nanotube array thin film based on dielectric electrophoresis according to claim 1, 2, or 4, characterized in that, The organic solvent in step 1 is one of toluene, xylene, and chloroform.

7. The method for preparing a single-chiral carbon nanotube array thin film based on dielectric electrophoresis according to claim 2, characterized in that, The dispersion process in step 1.1 uses an ultrasonic disruptor or a shear mixer.

8. The method for preparing a single-chiral carbon nanotube array thin film based on dielectric electrophoresis according to claim 1, characterized in that, In step 3, the peak voltage of the sinusoidal voltage is 0.1V to 100V, the frequency is 10Hz to 1MHz, and the electrophoresis duration is 2s to 180s. The selection of the electrophoresis duration must ensure that the high-purity monochiral carbon nanotube solution dropped into the gap between the electrophoresis electrodes is not completely evaporated.

9. A single-chiral carbon nanotube array thin film based on dielectric electrophoresis, characterized in that, Prepared by the method described in any one of claims 1-8.

10. An application of a single-chiral carbon nanotube array thin film based on dielectric electrophoresis, characterized in that, The thin film is prepared by any one of the methods described in claims 1-8 and is applied in the fields of electronics, optoelectronics and energy, and can be used to prepare radio frequency devices, optoelectronic devices and energy storage devices.

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