A field effect transistor based on solvent engineering and preparation method thereof

Abstract

The present invention discloses a field-effect transistor based on solvent engineering and a preparation method thereof. The preparation method uses a mixed solvent of chloroform (CF) and bromonaphthalene (BrN) to prepare a polymer solution, obtains an optimal solvent formula by regulating the solvent ratio, and uses a doctor blade coating method to prepare a high-quality large-area organic polymer film, thereby achieving a significant improvement in the carrier mobility of the field-effect transistor, thereby obtaining a high-mobility field-effect transistor. This will provide a new idea and method for promoting the industrial production and commercial application of field-effect transistors.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic field effect transistors, and in particular relates to a field effect transistor based on solvent engineering and a preparation method thereof. Background Art

[0002] Organic conjugated polymer field-effect transistors (OCPFETs) are field-effect transistors (FETs) composed of organic conjugated polymer semiconductors. They are active three-terminal devices that control the current between the source and drain electrodes via a gate voltage. Their applications include low-cost, large-area electronic products and biodegradable electronic devices, making them crucial in the semiconductor field. Solution-processed film formation technology, with its high efficiency and transport performance, is a research hotspot for the manufacture of low-cost, large-area electronic devices. However, conjugated polymers have high steric hindrance, making it difficult for the main chain and side chains to form highly ordered stacking during film formation from solution. Consequently, the carrier mobility in the film is low, making the realization of high-performance, large-area thin-film transistors difficult. Summary of the Invention

[0003] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a field effect transistor based on solvent engineering and a preparation method thereof, so as to solve the problem that high mobility large area thin film transistors are difficult to prepare under the prior art.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] A method for preparing a field-effect transistor based on solvent engineering, comprising coating an organic polymer solution on a modified silicon wafer, annealing to produce an organic polymer film, and evaporating electrodes on the organic polymer film to produce a field-effect transistor; the volume proportion of the CF in the solvent is 1% to 99%, with the remainder being BrN;

[0006] The solute of the organic polymer solution is PDVT-8, and the solvent is a mixed solution of CF and BrN;

[0007] The modified silicon wafer is a silicon wafer with an OTMS layer provided on its surface.

[0008] A further improvement of the present invention is:

[0009] Preferably, the volume proportion of CF in the solvent is 95%, and the volume proportion of BrN is 5%.

[0010] Preferably, the concentration of the organic polymer solution is 5 to 30 mg / mL.

[0011] Preferably, the organic polymer solution is prepared by adding PDVT-8 to a solvent, stirring at 20 to 65° C. for 2 to 20 hours, and allowing the solvent to stand until it reaches a thermodynamically stable state to obtain the organic polymer solution.

[0012] Preferably, the process of coating the modified silicon wafer with the organic polymer solution is as follows: the organic polymer solution is scraped onto the silicon wafer, the angle between the scraper and the silicon wafer is 10-15°, and the scraping speed is 50-300 mm / min.

[0013] Preferably, the annealing temperature is 150-200° C., and the annealing time is 5-30 minutes.

[0014] Preferably, the preparation process of the modified silicon wafer is:

[0015] Step 1, cleaning the silicon wafer;

[0016] Step 2, performing hydroxylation treatment on the silicon wafer;

[0017] Step 3: Spin-coat the OTMS solution on the surface of the silicon wafer. After spin coating, place the silicon wafer and ammonia water in a vacuum dryer at the same time, evacuate the solution until bubbles are generated in the ammonia water, and the OTMS on the surface of the silicon wafer is self-assembled.

[0018] Preferably, in step 1, the silicon wafer is cleaned with ultrapure water, acetone and isopropyl tone; and in step 2, the silicon wafer is hydroxylated with piranha wash solution.

[0019] Preferably, in step 3, the OTMS solution is OTMS diluted with TCE; the OTMS solution spin-coated on the silicon wafer surface is 10-200 μl, the spin-coating time is 10-120 s, and the spin-coating speed is 1000-5000 rpm.

[0020] A field effect transistor prepared by any one of the above preparation methods comprises a silicon wafer, an organic polymer film and an electrode arranged in sequence, wherein the size of the organic polymer film is (2-5) cm×(2-12) cm and the thickness is 10-40 μm.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The invention discloses a method for preparing a field effect transistor based on solvent engineering. The method uses a mixed solvent of chloroform (CF) and bromonaphthalene (BrN) to prepare a polymer solution, controls the solvent ratio to obtain an optimal solvent formula, and uses a doctor blade coating method to prepare a high-quality, large-area organic polymer film. The method introduces bromonaphthalene (BrN), a solvent with a high boiling point and selectivity for the main chain of the organic polymer, into the main solvent chloroform (CF), thereby regulating the orderly aggregation of the side chains and the main chain of the organic polymer in the solution and during the film formation process. The method then uses a printing technology to prepare a large-area fiber network as a carrier transmission channel, thereby significantly improving the carrier mobility of the field effect transistor, thereby obtaining a high-mobility field effect transistor. This method will provide a new idea and method for promoting the industrial production and commercial application of field effect transistors.

[0023] Furthermore, in the preparation process of the field effect transistor of the present invention, by optimizing the solvent ratio, a mixed solvent of bromonaphthalene (BrN) and chloroform (CF) is selected for the first time to prepare an organic polymer solution, thereby extending the film formation time of the film during the scraping process, giving the polymer a longer nucleation time to form a larger carrier transmission channel. And finally, the carrier mobility is obtained. Compared with the previous pure solvents, the film quality of the organic polymer is greatly improved, and the crystallinity and carrier transmission capacity of the film are improved. And the film is prepared by the scraping method, which greatly increases the area of ​​the organic film. The size of the organic film prepared by this method can be 4 to 60 cm 2 , providing favorable conditions for industrial large-scale production. Excellent carrier transport capability will also help field-effect transistors move towards commercial applications.

[0024] Furthermore, the scraping film-forming technology adopted in the present invention has a higher solution utilization rate, especially after adopting the binary solvent mixing method, the different boiling points and evaporation rates of the two solvents give the film a longer film-forming time, thereby forming a larger carrier transmission channel, greatly improving the charge transfer performance of the field effect transistor.

[0025] The present invention also discloses a field effect transistor based on solvent engineering, which is prepared by a scraping method and has excellent carrier transport capability. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a comparison chart of the output curves of the field effect transistor prepared by the method described in the embodiment of the present invention and that prepared by pure solvent.

[0027] Figure 2 3 is a comparison chart of the transfer curves of field effect transistors prepared by the method described in the embodiment of the present invention and pure solvent.

[0028] Figure 3 Comparison of scanning probe microscopy (AFM) images of organic polymer films prepared using the method described in the present invention and pure solvent. (a) shows a height image of the organic polymer film prepared using pure solvent; (b) shows a height image of the organic polymer film prepared using the method described in the present invention; (c) shows a phase image of the organic polymer film prepared using pure solvent; and (d) shows a phase image of the organic polymer film prepared using the method described in the present invention.

[0029] Figure 4 Comparative field emission ultrahigh-resolution transmission electron microscopy (TEM) images of organic polymer films prepared using the method described in this example and using pure solvent. (a) shows a TEM image of an organic polymer film prepared using pure solvent; (b) shows a TEM image of an organic polymer film prepared using the method described in this example.

[0030] Figure 5 This is a large-area scraped film prepared by the method described in the examples of the present invention.

[0031] Figure 6 Schematic diagram of a device prepared by the method described in an example of the present invention;

[0032] Figure 7 Figure 2 is the chemical structure of PDVT-8 used in the examples of the present invention. DETAILED DESCRIPTION

[0033] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0034] The invention discloses a large-area high-mobility field effect transistor device obtained through solvent engineering, which is prepared by the preparation method of the invention.

[0035] The present invention provides a method for preparing a large-area high-mobility field-effect transistor by solvent engineering, comprising the following steps:

[0036] Step 1, preparing a polymer solution using a binary mixed solvent of chloroform (CF) and bromonaphthalene (BrN);

[0037] First, weigh the solute organic polymer PDVT-8 (such as Figure 7 the substance indicated);

[0038] Next, a binary solvent mixture of CF and BrN in a volume ratio of (1-99):(1-99) is added to a glove box to prepare a solution with a concentration of 5-30 mg / mL, preferably 10 mg / mL, with the combined volume of CF and BrN in the solvent being 100%. Preferably, the volume ratio of chloroform in the solvent is 95% and the volume ratio of bromonaphthalene is 5%. This ratio creates a thin film with carrier transport channels that are most conducive to charge transport. The mixed solution is stirred at 20-65°C for 2-20 hours, preferably at 50°C for 6 hours, and then allowed to stand until thermodynamically stable before use. Upon reaching thermodynamic stability, the organic polymer PDVT-8 reaches a stable polymerization state.

[0039] Step 2: Clean the silicon wafer substrate: Select a six-inch silicon wafer with 300nm SiO2 and cut it into 10*3cm 2 The silicon wafers were ultrasonically cleaned with ultrapure water, acetone, and isopropyl alcohol for 30 minutes, respectively, and then dried with a nitrogen gun;

[0040] Step 3, hydroxylating the silicon wafer surface using piranha lotion;

[0041] A piranha wash solution, prepared by mixing concentrated sulfuric acid and hydrogen peroxide in a volume ratio of 7:3, was placed in the piranha wash solution for 30 minutes and then heated at 100°C for 30 minutes to thoroughly remove organic matter from the wafer. This formed a highly hydrophilic hydroxyl layer on the surface, facilitating the subsequent formation of a smoother film. The wafer was then ultrasonically cleaned twice with ultrapure water for 10 minutes each, dried with a nitrogen gun, and then dried at 120°C for 60 minutes. The wafer was then treated with UV-ozone for 15 minutes and then dried at 120°C for 60 minutes.

[0042] Through the processing of step 2 and step 3, impurities on the surface of the film are reduced, so that the film morphology finally formed subsequently is excellent and the device mobility is high.

[0043] Step 4, spin coating octadecyltrimethoxysilane (OTMS) to modify the silicon wafer;

[0044] First, an OTMS solution is diluted at a volume ratio of OTMS:TCE (trichloroethylene) = 1.3:1000 and vigorously stirred at 800 rpm for 3 minutes. Then, 10 to 200 μl, preferably 80 μl, of the OTMS solution is dripped onto a silicon wafer, allowed to stand for ten seconds, and then spin-coated at 1000 to 5000 rpm for 10 to 120 seconds, preferably at 3000 rpm for 30 seconds, to form an OTMS self-assembled monolayer on the silicon wafer surface.

[0045] Secondly, after the spin coating is completed, the silicon wafer and ammonia water are placed in a vacuum dryer at the same time, and the vacuum is applied until the ammonia water continuously produces small bubbles. The silicon wafer is allowed to stand in the ammonia atmosphere for ten hours to accelerate the bonding of OTMS to the silicon wafer surface and modify the SiO2 dielectric layer to make the dielectric layer and the polymer film in closer contact.

[0046] Step 5, cleaning the silicon wafer substrate again;

[0047] The modified silicon wafer was taken out and ultrasonically cleaned with ultrapure water, acetone, and toluene for 10 min respectively, blown dry with a nitrogen gun, and placed in an electric blast drying oven at 120°C for later use;

[0048] Step 6: Prepare a large-area organic polymer film with a thickness of about 10 to 40 nm by a doctor blade coating method;

[0049] Cool the dried silicon wafer to room temperature, place the silicon wafer on a doctor blade coater, make the angle between the doctor blade and the silicon wafer 10-15 degrees, and coat at a speed of 50-300 mm / min, preferably, the coating speed is 150 mm / min;

[0050] The prepared organic polymer film is annealed at 150-200° C. for 5-30 minutes to quickly evaporate the unvolatile solvent and accelerate the film formation process;

[0051] During the annealing process in this step, the solvent of the polymer solution is a mixed solvent of chloroform and bromonaphthalene. Bromonaphthalene has a high boiling point, which prolongs the film formation time during the annealing process, resulting in a large area of ​​the prepared film, which can reach (2 to 5) cm×(2 to 12) cm, and a thickness of 10 to 40 μm.

[0052] Step 7, evaporating a gold electrode on the prepared organic polymer film to obtain an organic field effect transistor device, wherein the evaporation thickness of the gold electrode is 60 nm;

[0053] Step 8: Use a 4200 detector to test the mobility of the organic field-effect transistor. The mobility test is performed under the condition of a bias voltage of 60V, a scan rate of ±1V / s, and a scan range of -60 to 0V.

[0054] The present invention uses a scraping method to prepare a field-effect transistor. The device structure consists of a silicon wafer with a 300nm SiO2 layer, an organic polymer film, and an Au electrode. In the present invention, the effect of a binary solvent on the charge transport properties of the polymer film is studied based on the organic polymer. CF has a strong interaction with the side chains, which promotes the aggregation of the polymer main chain. Due to the low boiling point of CF, it evaporates too quickly, resulting in a short film-forming time and only forming small-sized carrier transport channels. After the binary solvent is introduced, BN has a strong interaction with the main chain, causing the polymer to form a random coil. Its higher boiling point prolongs the film-forming time, allowing the polymer to form more orderly large-sized carrier transport channels, significantly improving the carrier mobility of the field-effect transistor.

[0055] Example 1

[0056] The present embodiment describes a method for preparing a large-area high-mobility field-effect transistor by solvent engineering, the best implementation method (using the abbreviation CB, such as Figures 1 to 6 The preparation steps include:

[0057] A polymer solution was prepared using a binary solvent mixture of chloroform (CF) and bromonaphthalene (BrN). First, the solute organic polymer PDVT-8 was weighed in air. Then, a 10 mg / ml solution of the binary solvent mixture of CF and BrN at a volume ratio of 98:2 was added to a glove box. The solution was stirred at 50°C for 6 hours and then allowed to stand for 3 days to reach thermodynamic stability.

[0058] Cleaning the silicon wafer substrate: Select a six-inch silicon wafer with 300nm SiO2 and cut it into 10*3cm 2 The silicon wafers were ultrasonically cleaned with ultrapure water, acetone, and isopropyl alcohol for 30 minutes, respectively, and then dried with a nitrogen gun;

[0059] Use piranha solution to hydroxylate the silicon wafer surface: prepare piranha solution by mixing concentrated sulfuric acid and hydrogen peroxide solution in a volume ratio of 7:3. Place the silicon wafer in the piranha solution for 30 minutes and heat at 100°C for 30 minutes. Then, ultrasonically clean the wafer twice with ultrapure water for 10 minutes each. Blow dry with a nitrogen gun and treat with UV ozone for 15 minutes before use.

[0060] Spin coating of octadecyltrimethoxysilane (OTMS) to modify the silicon wafer: First, dilute the OTMS solution at a volume ratio of OTMS:TCE = 1.3:1000 and vigorously stir at 800 rpm for 3 minutes; then, aspirate 80 μl of OTMS solution and drop it on the silicon wafer, let it stand for ten seconds, and then spin coat it at 3000 rpm for 30 seconds; secondly, after spin coating, place the silicon wafer and ammonia water in a vacuum desiccator at the same time, evacuate until the ammonia water continuously produces small bubbles, and let the silicon wafer stand in the ammonia atmosphere for ten hours to complete surface self-assembly.

[0061] Clean the silicon wafer substrate again: take out the modified silicon wafer, ultrasonically clean it with ultrapure water, acetone, and toluene for 10 minutes respectively, blow dry it with a nitrogen gun, and place it in an electric blast drying oven at 120°C for later use;

[0062] Large-area organic polymer films were prepared by doctor-coating: a dried silicon wafer was cooled to room temperature and placed on a doctor-coater with the doctor blade at an angle of 10-15° to the wafer. Coating was performed at a speed of 150 mm / min. The prepared organic polymer film was annealed at 150°C for 30 minutes.

[0063] Gold electrodes are evaporated on the prepared organic polymer film to obtain an organic field effect transistor device.

[0064] The mobility of organic field-effect transistors was tested using a 4200 detector.

[0065] Figure 1 The transfer curve of the field effect transistor is shown in FIG. 1 . The high mobility field effect transistor prepared by the present invention has a significantly improved device performance after adding the additive BrN. Figure 1 Compared with the field-effect transistor with pure solvent, the addition of additives showed a higher current and the curve line shape was optimized. Finally, the carrier mobility of the field-effect transistor with the introduction of additives was 1.47 cm 2 V -1 S -1 The field-effect transistor mobility of pure solvent is only 0.47 cm 2 V -1 S -1 .

[0066] Figure 2This is the output curve of the field-effect transistor. It can be seen from the output curve that the current is increased to more than twice the original after the introduction of the additive.

[0067] Figure 3 This is a scanning probe microscopy (AFM) image of an organic polymer film. It can be seen from the AFM image that after the addition of the additive, the film forms a large-area fibrous carrier transport network.

[0068] Figure 4 Transmission electron microscopy (TEM) images of organic polymer films. The TEM images also show that after the addition of additives, the films form large-scale clusters.

[0069] Figure 5 This is a diagram of a large-area organic polymer film being scraped down. The addition of additives allows for larger organic polymer films to be scraped down.

[0070] Figure 6 Device diagram of a field-effect transistor.

[0071] Figure 7 Chemical structure diagram of polymer PDVT-8.

[0072] Example 2

[0073] The method for preparing a large-area high-mobility field-effect transistor by solvent engineering described in this embodiment includes the following preparation steps:

[0074] A polymer solution was prepared using a binary solvent mixture of chloroform (CF) and bromonaphthalene (BrN). First, the solute organic polymer PDVT-8 was weighed in air. Then, a 10 mg / ml solution of the binary solvent mixture of CF and BrN at a volume ratio of 95:5 was added to a glove box. The solution was stirred at 50°C for 6 hours and then allowed to stand for 3 days to reach thermodynamic stability.

[0075] The other steps are the same as Example 1.

[0076] Example 3

[0077] The method for preparing a large-area high-mobility field-effect transistor by solvent engineering described in this embodiment includes the following preparation steps:

[0078] A polymer solution was prepared using a binary solvent mixture of chloroform (CF) and bromonaphthalene (BrN). First, the solute organic polymer PDVT-8 was weighed in air. Then, a 10 mg / ml solution of a 90:10 volume ratio of CF and BrN was added to a glove box. The solution was stirred at 50°C for 6 hours and then allowed to stand for 3 days to reach thermodynamic stability.

[0079] The other steps are the same as Example 1.

[0080] Example 4

[0081] The method for preparing a large-area high-mobility field-effect transistor by solvent engineering described in this embodiment includes the following preparation steps:

[0082] A polymer solution was prepared using a binary solvent mixture of chloroform (CF) and bromonaphthalene (BrN). First, the solute organic polymer PDVT-8 was weighed in air. Then, a 10 mg / ml solution of the binary solvent mixture of CF and BrN at a volume ratio of 95:5 was added to a glove box. The solution was stirred at 50°C for 6 hours and then allowed to stand for 3 days to reach thermodynamic stability.

[0083] Large-area organic polymer films were prepared by doctor-coating: a dried silicon wafer was cooled to room temperature and placed on a doctor-coater with the doctor blade at an angle of 10-15° to the wafer. Coating was performed at a speed of 150 mm / min. The prepared organic polymer film was annealed at 160°C for 30 minutes.

[0084] The other steps are the same as Example 1.

[0085] Example 5

[0086] The method for preparing a large-area high-mobility field-effect transistor by solvent engineering described in this embodiment includes the following preparation steps:

[0087] A polymer solution was prepared using a binary solvent mixture of chloroform (CF) and bromonaphthalene (BrN). First, the solute organic polymer PDVT-8 was weighed in air. Then, a 10 mg / ml solution of the binary solvent mixture of CF and BrN at a volume ratio of 95:5 was added to a glove box. The solution was stirred at 50°C for 6 hours and then allowed to stand for 3 days to reach thermodynamic stability.

[0088] Large-area organic polymer films were prepared by doctor-coating: a dried silicon wafer was cooled to room temperature and placed on a doctor-coater with the doctor blade at an angle of 10-15° to the wafer, with coating performed at a speed of 150 mm / min. The prepared organic polymer film was annealed at 170°C for 30 minutes.

[0089] The other steps are the same as Example 1.

[0090] Example 6

[0091] The method for preparing a large-area high-mobility field-effect transistor by solvent engineering described in this embodiment includes the following preparation steps:

[0092] A polymer solution was prepared using a binary solvent mixture of chloroform (CF) and bromonaphthalene (BrN). First, the solute organic polymer PDVT-8 was weighed in air. Then, a 10 mg / ml solution of the binary solvent mixture of CF and BrN at a volume ratio of 95:5 was added to a glove box. The solution was stirred at 50°C for 6 hours and then allowed to stand for 3 days to reach thermodynamic stability.

[0093] Large-area organic polymer films were prepared by doctor-coating: a dried silicon wafer was cooled to room temperature and placed on a doctor-coater with the doctor blade at an angle of 10-15° to the wafer. Coating was performed at a speed of 150 mm / min. The prepared organic polymer film was annealed at 180°C for 30 minutes.

[0094] The other steps are the same as Example 1.

[0095] Example 7

[0096] The method for preparing a large-area high-mobility field-effect transistor by solvent engineering described in this embodiment includes the following preparation steps:

[0097] A polymer solution was prepared using a binary solvent mixture of chloroform (CF) and bromonaphthalene (BrN). First, the solute organic polymer PDVT-8 was weighed in air. Then, a 10 mg / ml solution of the binary solvent mixture of CF and BrN at a volume ratio of 95:5 was added to a glove box. The solution was stirred at 50°C for 6 hours and then allowed to stand for 3 days to reach thermodynamic stability.

[0098] Large-area organic polymer films were prepared by doctor-coating: a dried silicon wafer was cooled to room temperature and placed on a doctor-coater with the doctor blade at an angle of 10-15° to the wafer. Coating was performed at a speed of 150 mm / min. The prepared organic polymer film was annealed at 190°C for 30 minutes.

[0099] The other steps are the same as Example 1.

[0100] Example 8

[0101] The method for preparing a large-area high-mobility field-effect transistor by solvent engineering described in this embodiment includes the following preparation steps:

[0102] A polymer solution was prepared using a binary solvent mixture of chloroform (CF) and bromonaphthalene (BrN). First, the solute organic polymer PDVT-8 was weighed in air. Then, a 10 mg / ml solution of the binary solvent mixture of CF and BrN at a volume ratio of 95:5 was added to a glove box. The solution was stirred at 50°C for 6 hours and then allowed to stand for 3 days to reach thermodynamic stability.

[0103] Large-area organic polymer films were prepared by the doctor blade coating method: the dried silicon wafer was cooled to room temperature, and the silicon wafer was placed on a doctor blade coater with the angle of the doctor blade to the silicon wafer being 10-15 degrees, and the coating was performed at a speed of 150 mm / min; the prepared organic polymer film was annealed at 200°C for 30 min.

[0104] The other steps are the same as Example 1.

[0105] Example 9

[0106] The method for preparing a large-area high-mobility field-effect transistor by solvent engineering described in this embodiment includes the following preparation steps:

[0107] A polymer solution was prepared using a binary solvent mixture of chloroform (CF) and bromonaphthalene (BrN). First, the solute organic polymer PDVT-8 was weighed in air. Then, a 10 mg / ml solution of the binary solvent mixture of CF and BrN at a volume ratio of 95:5 was added to a glove box. The solution was stirred at 50°C for 6 hours and then allowed to stand for 3 days to reach thermodynamic stability.

[0108] Large-area organic polymer films were prepared by the doctor blade coating method: the dried silicon wafer was cooled to room temperature, and the silicon wafer was placed on a doctor blade coater with the angle of the doctor blade to the silicon wafer being 10-15 degrees, and the coating was performed at a speed of 150 mm / min; the prepared organic polymer film was annealed at 200°C for 15 minutes.

[0109] The other steps are the same as Example 1.

[0110] Example 10

[0111] The method for preparing a large-area high-mobility field-effect transistor by solvent engineering described in this embodiment includes the following preparation steps:

[0112] A polymer solution was prepared using a binary solvent mixture of chloroform (CF) and bromonaphthalene (BrN). First, the solute organic polymer PDVT-8 was weighed in air. Then, a 10 mg / ml solution of the binary solvent mixture of CF and BrN at a volume ratio of 95:5 was added to a glove box. The solution was stirred at 50°C for 6 hours and then allowed to stand for 3 days to reach thermodynamic stability.

[0113] Large-area organic polymer films were prepared by doctor-coating: a dried silicon wafer was cooled to room temperature and placed on a doctor-coater with the doctor blade at an angle of 10-15° to the wafer. The film was coated at a speed of 150 mm / min. The prepared organic polymer film was annealed at 200°C for 5 minutes.

[0114] The other steps are the same as Example 1.

[0115] Example 11

[0116] The method for preparing a large-area high-mobility field-effect transistor by solvent engineering described in this embodiment includes the following preparation steps:

[0117] A polymer solution was prepared using a binary solvent mixture of chloroform (CF) and bromonaphthalene (BrN). First, the solute organic polymer PDVT-8 was weighed in air. A 99:1 volume ratio of CF and BrN was then added to a 20 mg / ml solution in a glove box. The solution was stirred at 20°C for 20 hours and then allowed to stand for 3 days to reach thermodynamic stability.

[0118] The silicon wafer was modified by spin coating octadecyltrimethoxysilane (OTMS): first, the OTMS solution was diluted according to the volume ratio of OTMS:TCE = 1.3:1000 and vigorously stirred at 800 rpm for 3 minutes; then, 10 μl of OTMS solution was aspirated and dropped onto the silicon wafer, allowed to stand for ten seconds, and then spin coated at 1000 rpm for 120 seconds; secondly, after the spin coating, the silicon wafer and ammonia water were placed in a vacuum desiccator at the same time, and vacuumed until the ammonia water continuously produced small bubbles. The silicon wafer was allowed to stand in the ammonia atmosphere for ten hours to complete the surface self-assembly.

[0119] Large-area organic polymer films were prepared by the doctor blade coating method: the dried silicon wafer was cooled to room temperature, and the silicon wafer was placed on a doctor blade coater with the angle of the doctor blade to the silicon wafer being 10-15 degrees, and the coating was performed at a speed of 50 mm / min; the prepared organic polymer film was annealed at 200°C for 15 minutes.

[0120] The other steps are the same as Example 1.

[0121] Example 12

[0122] The method for preparing a large-area high-mobility field-effect transistor by solvent engineering described in this embodiment includes the following preparation steps:

[0123] A polymer solution was prepared using a binary solvent mixture of chloroform (CF) and bromonaphthalene (BrN). First, the solute organic polymer PDVT-8 was weighed in air. A 10 mg / ml solution of the binary solvent mixture of CF and BrN at a volume ratio of 1:99 was added to a glove box. The solution was stirred at 30°C for 15 hours and then allowed to stand for 3 days to reach thermodynamic stability.

[0124] The silicon wafer was modified by spin coating of octadecyltrimethoxysilane (OTMS): first, the OTMS solution was diluted according to the volume ratio of OTMS:TCE = 1.3:1000 and vigorously stirred at 800 rpm for 3 minutes; then, 50 μl of OTMS solution was aspirated and dropped onto the silicon wafer, allowed to stand for ten seconds, and then spin coated at 2000 rpm for 80 seconds; secondly, after the spin coating, the silicon wafer and ammonia water were placed in a vacuum desiccator at the same time, and vacuumed until the ammonia water continuously produced small bubbles. The silicon wafer was allowed to stand in the ammonia atmosphere for ten hours to complete the surface self-assembly.

[0125] Large-area organic polymer films were prepared by the doctor blade coating method: the dried silicon wafer was cooled to room temperature, and the silicon wafer was placed on a doctor blade coater with the angle of the doctor blade to the silicon wafer being 10-15 degrees, and the coating was performed at a speed of 100 mm / min; the prepared organic polymer film was annealed at 200°C for 15 minutes.

[0126] The other steps are the same as Example 1.

[0127] Example 13

[0128] The method for preparing a large-area high-mobility field-effect transistor by solvent engineering described in this embodiment includes the following preparation steps:

[0129] A polymer solution was prepared using a binary solvent mixture of chloroform (CF) and bromonaphthalene (BrN). First, the solute organic polymer PDVT-8 was weighed in air. A 15 mg / ml solution of the binary solvent mixture of CF and BrN (90:10 by volume) was added to a glove box. The solution was stirred at 40°C for 10 hours and then allowed to stand for 3 days to reach thermodynamic stability.

[0130] Spin coating of octadecyltrimethoxysilane (OTMS) to modify the silicon wafer: First, dilute the OTMS solution at a volume ratio of OTMS:TCE = 1.3:1000 and vigorously stir at 800 rpm for 3 minutes; then, aspirate 100 μl of OTMS solution and drop it on the silicon wafer, let it stand for ten seconds, and then spin coat it at 3000 rpm for 60 seconds; secondly, after the spin coating is completed, place the silicon wafer and ammonia water in a vacuum desiccator at the same time, evacuate until the ammonia water continuously produces small bubbles, and let the silicon wafer stand in the ammonia atmosphere for ten hours to complete surface self-assembly.

[0131] Large-area organic polymer films were prepared by the doctor blade coating method: the dried silicon wafer was cooled to room temperature, and the silicon wafer was placed on a doctor blade coater with the angle of the doctor blade to the silicon wafer being 10-15 degrees, and the coating was performed at a speed of 150 mm / min; the prepared organic polymer film was annealed at 200°C for 15 minutes.

[0132] The other steps are the same as Example 1.

[0133] Example 14

[0134] The method for preparing a large-area high-mobility field-effect transistor by solvent engineering described in this embodiment includes the following preparation steps:

[0135] A polymer solution was prepared using a binary solvent mixture of chloroform (CF) and bromonaphthalene (BrN). First, the solute organic polymer PDVT-8 was weighed in air. A 20 mg / ml solution of a 70:30 volume ratio of CF and BrN was added to a glove box. The solution was stirred at 50°C for 5 hours and then allowed to stand for 3 days to reach thermodynamic stability.

[0136] The silicon wafer was modified by spin coating octadecyltrimethoxysilane (OTMS): First, the OTMS solution was diluted at a volume ratio of OTMS:TCE = 1.3:1000 and vigorously stirred at 800 rpm for 3 minutes; then 150 μl of OTMS solution was aspirated and dropped onto the silicon wafer, allowed to stand for ten seconds, and then spin coated at 4000 rpm for 50 seconds; secondly, after the spin coating, the silicon wafer and ammonia water were placed in a vacuum desiccator at the same time, and the vacuum was evacuated until the ammonia water continuously produced small bubbles. The silicon wafer was allowed to stand in the ammonia atmosphere for ten hours to complete the surface self-assembly.

[0137] Large-area organic polymer films were prepared by the doctor blade coating method: the dried silicon wafer was cooled to room temperature, and the silicon wafer was placed on a doctor blade coater with the angle of the doctor blade to the silicon wafer being 10-15 degrees, and the coating was performed at a speed of 200 mm / min; the prepared organic polymer film was annealed at 200°C for 15 minutes.

[0138] The other steps are the same as Example 1.

[0139] Example 15

[0140] The method for preparing a large-area high-mobility field-effect transistor by solvent engineering described in this embodiment includes the following preparation steps:

[0141] A polymer solution was prepared using a binary solvent mixture of chloroform (CF) and bromonaphthalene (BrN). First, the solute organic polymer PDVT-8 was weighed in air. Then, a 50:50 volume ratio of CF and BrN binary solvent mixture was added to a 20 mg / ml solution in a glove box. The solution was stirred at 50°C for 5 hours and then allowed to stand for 3 days to reach thermodynamic stability.

[0142] The silicon wafer was modified by spin coating octadecyltrimethoxysilane (OTMS): First, the OTMS solution was diluted at a volume ratio of OTMS:TCE = 1.3:1000 and vigorously stirred at 800 rpm for 3 minutes; then 150 μl of OTMS solution was aspirated and dropped onto the silicon wafer, allowed to stand for ten seconds, and then spin coated at 4000 rpm for 50 seconds; secondly, after the spin coating, the silicon wafer and ammonia water were placed in a vacuum desiccator at the same time, and the vacuum was evacuated until the ammonia water continuously produced small bubbles. The silicon wafer was allowed to stand in the ammonia atmosphere for ten hours to complete the surface self-assembly.

[0143] Large-area organic polymer films were prepared by the doctor blade coating method: the dried silicon wafer was cooled to room temperature, and the silicon wafer was placed on a doctor blade coater with the angle of the doctor blade to the silicon wafer being 10-15 degrees, and the coating was performed at a speed of 200 mm / min; the prepared organic polymer film was annealed at 200°C for 15 minutes.

[0144] The other steps are the same as Example 1.

[0145] Example 16

[0146] The method for preparing a large-area high-mobility field-effect transistor by solvent engineering described in this embodiment includes the following preparation steps:

[0147] A polymer solution was prepared using a binary solvent mixture of chloroform (CF) and bromonaphthalene (BrN). First, the solute organic polymer PDVT-8 was weighed in air. Then, a 30 mg / ml solution of a binary solvent mixture of CF and BrN at a volume ratio of 20:80 was added to a glove box. The solution was stirred at 65°C for 2 hours and then allowed to stand for 3 days to reach thermodynamic stability.

[0148] The silicon wafer was modified by spin coating octadecyltrimethoxysilane (OTMS): First, the OTMS solution was diluted at a volume ratio of OTMS:TCE = 1.3:1000 and vigorously stirred at 800 rpm for 3 minutes; then 150 μl of OTMS solution was aspirated and dropped onto the silicon wafer, allowed to stand for ten seconds, and then spin coated at 3500 rpm for 10 seconds; secondly, after the spin coating, the silicon wafer and ammonia water were placed in a vacuum desiccator at the same time, and the vacuum was evacuated until the ammonia water continuously produced small bubbles. The silicon wafer was allowed to stand in the ammonia atmosphere for ten hours to complete the surface self-assembly.

[0149] Large-area organic polymer films were prepared by the doctor blade coating method: the dried silicon wafer was cooled to room temperature, and the silicon wafer was placed on a doctor blade coater with the angle of the doctor blade to the silicon wafer being 10-15 degrees, and the coating was performed at a speed of 300 mm / min; the prepared organic polymer film was annealed at 200°C for 15 minutes.

[0150] The other steps are the same as Example 1.

[0151] Comparative Example 1

[0152] The method of preparing a large-area high-mobility field-effect transistor by solvent engineering according to the present invention comprises the following preparation steps:

[0153] A polymer solution was prepared using a binary solvent mixture of chloroform (CF) and bromonaphthalene (BrN). First, the solute organic polymer PDVT-8 was weighed in air. A 1:0 volume ratio of CF and BrN was then added to a 10 mg / ml solution in a glove box. The solution was stirred at 50°C for 6 hours and then allowed to stand for 3 days to reach thermodynamic stability.

[0154] The other steps are the same as Example 1.

[0155] Comparative Example 2

[0156] The method of preparing a large-area high-mobility field-effect transistor by solvent engineering according to the present invention comprises the following preparation steps:

[0157] A polymer solution was prepared using a binary solvent mixture of chloroform (CF) and bromonaphthalene (BrN). First, the solute organic polymer PDVT-8 was weighed in air. A 0:1 volume ratio of CF and BrN was then added to a 10 mg / ml solution in a glove box. The solution was stirred at 50°C for 6 hours and then allowed to stand for 3 days to reach thermodynamic stability.

[0158] The other steps are the same as Example 1.

[0159] The test results are shown in Table 1.

[0160] Table 1

[0161]

[0162] The present invention relates to a field effect transistor device, in particular to a method for preparing a large-area high-mobility field effect transistor through solvent engineering.

[0163] Step 1: Solution preparation; Step 2: Cleaning the silicon wafer substrate; Step 3: Hydroxylating the silicon wafer surface with piranha wash; Step 4: Modifying the silicon wafer with spin coating of octadecyltrimethoxysilane; Step 5: Cleaning the silicon wafer substrate again; Step 6: Preparing a large-area organic polymer film by doctor blade coating; Step 7: Vapor deposition of electrodes; Step 8: Testing transistor mobility. Organic polymer films prepared using binary mixed solvents exhibit high crystallinity, strong aggregation, and large carrier transport fibers, effectively improving the carrier mobility of field-effect transistors. This provides a more fundamental and rational approach and method for preparing high-mobility field-effect transistors. Their excellent mobility will also help promote the commercialization of field-effect transistors.

[0164] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a field effect transistor based on solvent engineering, characterized in that: An organic polymer solution is coated on a modified silicon wafer, and an organic polymer film is obtained after annealing, and an electrode is evaporated on the organic polymer film to obtain a field effect transistor; The solute of the organic polymer solution is PDVT-8, and the solvent is a mixed solution of chloroform and bromonaphthalene; the volume proportion of chloroform in the solvent is 1% to 99%, and the balance is bromonaphthalene; the structural formula of the PDVT-8 is: The modified silicon wafer is a silicon wafer with an OTMS layer provided on the surface.

2. The method for preparing a field effect transistor based on solvent engineering according to claim 1, characterized in that: The volume proportion of the chloroform in the solvent is 95%, and the volume proportion of bromonaphthalene is 5%.

3. The method for preparing a field effect transistor based on solvent engineering according to claim 1, characterized in that: The concentration of the organic polymer solution is 5-30 mg / mL.

4. The method for preparing a field effect transistor based on solvent engineering according to claim 1, characterized in that: The preparation process of the organic polymer solution is as follows: PDVT-8 is added to a solvent, stirred at 20-65°C for 2-20 hours, and allowed to stand until a thermodynamically stable state is reached to obtain the organic polymer solution.

5. The method for preparing a field effect transistor based on solvent engineering according to claim 1, characterized in that: The process of coating the organic polymer solution on the modified silicon wafer is as follows: the organic polymer solution is scraped onto the silicon wafer, the angle between the scraper and the silicon wafer is 10-15 degrees, and the scraping speed is 50-300 mm / min.

6. The method for preparing a field effect transistor based on solvent engineering according to claim 1, characterized in that: The annealing temperature is 150~200℃, and the annealing time is 5~30min.

7. The method for preparing a field effect transistor based on solvent engineering according to any one of claims 1 to 6, characterized in that: The preparation process of modified silicon wafer is as follows: Step 1, cleaning the silicon wafer; Step 2, performing hydroxylation treatment on the silicon wafer; Step 3: Spin-coat the OTMS solution on the surface of the silicon wafer. After spin coating, place the silicon wafer and ammonia water in a vacuum dryer at the same time, evacuate the solution until bubbles are generated in the ammonia water, and the OTMS on the surface of the silicon wafer is self-assembled.

8. The method for preparing a field effect transistor based on solvent engineering according to claim 7, characterized in that: In step 1, the silicon wafer is cleaned with ultrapure water, acetone, and isopropyl ketone; in step 2, the silicon wafer is hydroxylated with piranha wash solution.

9. The method for preparing a field effect transistor based on solvent engineering according to claim 7, characterized in that: In step 3, the OTMS solution is OTMS diluted with TCE; the OTMS solution spin-coated on the silicon wafer surface is 10-200 μL, the spin-coating time is 10-120 s, and the spin-coating speed is 1000-5000 rpm.

10. A field effect transistor prepared by the preparation method according to any one of claims 1 to 9, characterized in that: The invention comprises a silicon wafer, an organic polymer film and an electrode which are arranged in sequence. The size of the organic polymer film is (2-5) cm×(2-12) cm and the thickness is 10-40 μm.

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