Organic donor-acceptor charge transfer eutectic self-supporting film, polymer self-supporting film, flexible transistor sensor of organic donor-acceptor charge transfer eutectic self-supporting film and preparation method of flexible transistor sensor

Abstract

The invention discloses an organic donor-acceptor charge transfer eutectic self-supporting film, a polymer self-supporting film, a flexible transistor sensor thereof and a preparation method of the flexible transistor sensor. The sensor comprises an interdigital electrode, a semiconductor layer, a dielectric layer and the like, the semiconductor layer is an organic donor-acceptor charge transfer eutectic film, the dielectric layer is a polymer film, and the semiconductor layer and the dielectric layer are both prepared by a'water-solution-air 'interface film forming method; the preparation method of the sensor comprises the following steps: preparing the interdigital electrode on the substrate, spreading and volatilizing a mixed solution containing an organic donor and an organic acceptor on the water surface, and forming a uniform organic eutectic semiconductor layer on the surface of the interdigital electrode; and then, forming a polymer dielectric layer on the semiconductor layer by using the polymer solution through the same interface method, and finally preparing the gate electrode. According to the invention, various self-supporting single-crystal, polycrystal and amorphous films can be obtained, the dependence of a traditional spin-coating method on a substrate is overcome, and a novel semiconductor material for flexible sensing and a sensing mechanism are developed.

Description

Technical Field

[0001] This invention relates to the fabrication of self-supporting thin films, novel sensing mechanisms, and applications of flexible thin-film transistor sensors, particularly to organic donor-acceptor charge transfer eutectic self-supporting thin films and polymer self-supporting thin films, as well as their flexible transistor sensors and fabrication methods. Background Technology

[0002] With the development of artificial intelligence and smart medical technologies, increasingly higher demands are being placed on sensor performance. Tactile sensors are among the most widely used types of sensors, and various materials and device forms have been developed. However, past research has primarily focused on sensing changes in the resistance of materials or the capacitance of devices. The sensitivity of sensing resistance changes is relatively low, mainly because under weak external forces, the deformation of a single material is limited, resulting in a small change in resistance. To meet the demands of the intelligent era, it is necessary to develop more diverse sensing materials and novel sensing mechanisms to improve sensor performance. Summary of the Invention

[0003] To address the limitations of resistance-based devices in the aforementioned background technologies, such as their limited sensing performance, and the constraints of traditional transistor semiconductor and dielectric layer fabrication techniques, this invention proposes a novel material for tactile sensors based on resistance changes—an organic donor-acceptor charge transfer eutectic self-supporting thin film. It also invents a novel fabrication method for the semiconductor and dielectric layers of flexible transistors and proposes a new sensing mechanism, which holds promise for applications in the fields of tactile sensing in medicine and artificial intelligence technologies.

[0004] The technical solution adopted in this invention is as follows: I. A method for preparing an organic donor-acceptor charge transfer eutectic self-supporting thin film The method includes the following steps: S11. Dissolve the organic donor and the organic acceptor in a first specific solvent, heat and mix them at a certain temperature for a period of time to obtain a first clear solution; then add the antisolvent to obtain a mixed solution; Specifically, an organic donor with a concentration not exceeding 20 mg / mL and an organic acceptor with a concentration not exceeding 20 mg / mL are dissolved in a first specific solvent and heated at 50-80 °C. o Heating and stirring at C for 1-5 hours yields a first clear solution. Then, adding no more than 5 vol% of antisolvent to the first clear solution, sonicating at room temperature for 1-5 minutes to disperse the antisolvent, and finally sealing and allowing it to stand for 5-24 hours, yields a mixed solution. In practice, 0-5 vol% of antisolvent is added depending on the ease of crystallization of the donor-acceptor eutectic. To obtain a complete eutectic film, the solution must have a low saturated vapor pressure to ensure slow evaporation. An appropriate concentration is selected based on the final film thickness requirements.

[0005] The organic donors include poly(3-thiophene) (P3HT, P3DDT, PBTTT), polyaniline (PANI), polyisothioindene (PITN), tetrathiofulvalene (TTF), pentacene, tetra(dimethylamino)ethylene (TDAE), or DNA, etc., while the organic acceptor is fullerene (C... 60 The solvents are pyromellitic tetramethylamine diimide (PMDI), perylene diimide (PDI), anthraquinone (AQ), tetrachlorobenzoquinone (CA), tetrafluorop-benzoquinone (TFQ), or tetracyanoethylene (TCNE), etc.; the first specific solvent is chlorobenzene or dimethyl sulfoxide; the antisolvent is acetonitrile, carbon disulfide, or dimethylformamide, etc.

[0006] S12. Clean the substrate and place it in a petri dish. Add deionized water to the petri dish. Specifically, immerse the substrate in deionized water, acetone, or isopropanol for ultrasonic cleaning for 5-10 minutes, then clean it in a UV-ozone or plasma cleaner for 5-10 minutes to obtain a clean hydrophilic surface. Place the cleaned substrate in a petri dish and add an appropriate amount of deionized water. The substrate can be flexible polyethylene terephthalate (PET), glass, silicon, or sapphire, etc.

[0007] S13. Then, drop the mixed clear solution into the petri dish at a certain speed and let it stand for a period of time. Specifically, based on the water surface area, a suitable amount of the mixed solution obtained in step S11 is continuously dripped into the petri dish from the edge at a speed of 0.01-0.1 mL / min using a pipette. The mixture floats on the water surface and is left to stand for 12-24 hours to allow the solution to completely evaporate. In practice, an appropriate volume is selected based on the final film thickness requirements. To ensure that the solution can float on the water surface and form a complete film, the following two points need to be met: the volume of the added solution and the rate of addition must meet the requirements, and the addition must be continuous. Surface tension control of water and the added solution: depending on the situation, determine which solution can float on the water surface and whether it is necessary to control the surface tension of the water by using a water-miscible reagent or changing the temperature.

[0008] S14. Finally, annealing is performed to obtain an organic donor-acceptor charge-transfer eutectic self-supporting thin film; specifically, the film is slowly extracted onto the substrate, and then annealed at 50-120°C. o Vacuum annealing was performed at C for 2-12 hours to remove dissolved oxygen and water molecules from the film and promote crystallization, thus preparing an organic donor-acceptor charge transfer eutectic self-supporting film on the substrate.

[0009] II. A method for preparing a polymer self-supporting thin film The method includes the following steps: S21. Dissolve the polymer in a second specific solvent, heat and mix at a certain temperature for a period of time to obtain a second clear solution; specifically, dissolve 1-100 mg / mL of the polymer in the second specific solvent, and heat and mix at 50-70 °C for a period of time to obtain a second clear solution. o The mixture is heated and stirred at temperature C for 2-5 hours to obtain a second clear solution. The polymer is methyl methacrylate (PMMA), polystyrene (PS), or polyvinylidene fluoride (PVDF), and the second specific solvent is toluene or dimethylformamide.

[0010] S22. Clean the substrate and place it in a petri dish. Add deionized water to the petri dish. Specifically, immerse the substrate in deionized water, acetone, or isopropanol and ultrasonically clean it for 5-10 minutes. Then clean it in a UV-ozone or plasma cleaner for 5-10 minutes to obtain a clean hydrophilic surface. Place the cleaned substrate in a petri dish and add an appropriate amount of deionized water to the petri dish. The substrate is flexible polyethylene terephthalate (PET), glass, silicon, or sapphire, etc.

[0011] S23. Then, the second clear solution is dripped into the petri dish at a certain speed and left to stand for a period of time. Specifically, according to the water surface area, an appropriate amount of the second clear solution obtained in step S21 is dripped into the petri dish from the edge at a speed of 0.01-0.1 mL / min and continuously. The second clear solution floats on the water surface and is left to stand for 12-24 hours to allow the solution to completely evaporate. S24. Finally, annealing is performed to obtain a polymer self-supporting film. Specifically, the film is slowly extracted onto the substrate, and then annealed at 50-120°C. o Vacuum annealing was performed at C for 2-12 hours to remove dissolved oxygen and water molecules from the film, thus preparing a polymer self-supporting film on the substrate.

[0012] The method for preparing the flexible thin film of this invention is also applicable to other materials, such as organic materials and inorganic nanocrystalline materials, that cannot be dissolved or dispersed in solution. The thickness of the thin film is affected by the solution concentration and volume, as well as the surface area of ​​the water. The quality of the organic semiconductor is affected by the final vacuum annealing process. The flexible thin film of this invention has important applications in flexible devices such as transistors, displays, detectors, and solar cells, and is not limited to sensor applications.

[0013] III. A flexible transistor sensor based on an organic donor-acceptor charge transfer eutectic self-supporting thin film. Flexible transistor sensors are transistor devices with flexibility and force sensing capabilities; the semiconductor layer is an organic donor-acceptor charge transfer eutectic self-supporting thin film, and the dielectric layer is a polymer self-supporting thin film.

[0014] In a specific implementation, the flexible transistor includes interdigitated electrodes, a flexible substrate, a semiconductor layer, a dielectric layer, and a gate electrode. The interdigitated electrodes are arranged on the flexible substrate, the semiconductor layer is tightly attached to the interdigitated electrodes, the dielectric layer is tightly attached to the semiconductor layer, and a gate electrode is disposed on the dielectric layer. The gate electrode is in contact with an external object. In this design, both the semiconductor layer and the dielectric layer are self-supporting thin films. The semiconductor layer is an organic donor-acceptor charge transfer eutectic self-supporting thin film, and the dielectric layer is a polymer self-supporting thin film. The transistor sensor is a transistor device with flexibility and force sensing capabilities.

[0015] The organic donor-acceptor charge transfer eutectic self-supporting film is an organic donor-acceptor charge transfer eutectic film containing π electrons. The organic donor is poly(3-thiophene) (P3HT, P3DDT, PBTTT), polyaniline (PANI), polyisothioindene (PITN), tetrathiofulvalene (TTF), pentacene, tetra(dimethylamino)ethylene (TDAE), or DNA, etc., and the organic acceptor is fullerene (C 60 Polymer self-supporting films include pyromellitic tetramethylamine diimide (PMDI), perylene diimide (PDI), anthraquinone (AQ), tetrachlorobenzoquinone (CA), tetrafluorop-benzoquinone (TFQ), or tetracyanoethylene (TCNE), etc.; and polymethyl methacrylate (PMMA), polystyrene (PS), or polyvinylidene fluoride (PVDF) films, which have self-supporting properties.

[0016] In specific implementation, the donor-acceptor pair of the organic donor-acceptor charge transfer eutectic self-supporting film is P3HT-C. 60 Or PBTTT-TCNQ.

[0017] IV. Fabrication Method of Flexible Transistor Sensor Based on Organic Donor-Acceptor Charge Transfer Eutectic Self-Supported Thin Film The method includes the following steps: S1. Cleaning the substrate: Immerse the substrate in deionized water, acetone or isopropanol and ultrasonically clean for 5-10 minutes, then clean it in a UV-ozone or plasma cleaner for 5-10 minutes to obtain a clean hydrophilic surface. Then place the cleaned substrate in a petri dish and add an appropriate amount of deionized water to the petri dish. S2. A metal electrode is deposited on the cleaned substrate by vacuum thermal evaporation using photolithography to serve as an interdigitated electrode. Specifically, a metal electrode with a thickness of 50-100 nm is deposited on the cleaned substrate by vacuum thermal evaporation using conventional photolithography to prepare the interdigitated electrode, thus obtaining a substrate with interdigitated electrodes. The electrode width is 20-500 µm, the electrode length is 0.2-1 mm, and the transistor channel width is 10-500 µm.

[0018] S3. Prepare organic donor-acceptor charge transfer eutectic self-supporting thin films on the surface of interdigitated electrodes: S31. Dissolve an organic donor with a concentration not exceeding 20 mg / mL and an organic acceptor with a concentration not exceeding 20 mg / mL in a first specific solvent, and heat at 50-80 °C. o The mixture is heated and stirred at temperature C for 1-5 hours to obtain the first clear solution. In practice, depending on the ease of crystallization of the donor-acceptor co-crystallization, 0-5 vol% antisolvent is added, and the solution is sonicated at room temperature for 1-5 minutes to disperse the antisolvent, then sealed and allowed to stand for 5-24 hours; then, no more than 5 vol% antisolvent is added to the first clear solution, and the solution is sonicated at room temperature for 1-5 minutes to disperse the antisolvent, then sealed and allowed to stand for 5-24 hours to obtain a mixed solution; in practice, depending on the ease of crystallization of the donor-acceptor co-crystallization, 0-5 vol% antisolvent is added. The organic donors include poly(3-thiophene) (P3HT, P3DDT, PBTTT), polyaniline (PANI), polyisothioindene (PITN), tetrathiofulvalene (TTF), pentacene, tetra(dimethylamino)ethylene (TDAE), or DNA, etc., while the organic acceptor is a fullerene (C... 60 The solvents used are pyromellitic tetramethylamine diimide (PMDI), perylene diimide (PDI), anthraquinone (AQ), tetrachlorobenzoquinone (CA), tetrafluorop-benzoquinone (TFQ), or tetracyanoethylene (TCNE), etc.; the first specific solvent is chlorobenzene or dimethyl sulfoxide; the antisolvent is acetonitrile, carbon disulfide, or dimethylformamide, etc. S32. Place the substrate with interdigitated electrodes in a culture dish, and then add an appropriate amount of deionized water to the culture dish; wherein the substrate is flexible polyethylene terephthalate (PET) or polydimethylsiloxane (PDMS). S33. Then, according to the water surface area, use a pipette to continuously drop an appropriate amount of the mixed solution obtained in step S31 from the edge into the petri dish at a speed of 0.01-0.1 mL / min. The mixed solution floats on the water surface and is left to stand for 12-24 hours to allow the solution to evaporate completely. S34. Slowly extract the thin film onto the substrate: then at 70-120°C... o Vacuum annealing at C for 12-24 h removes dissolved oxygen and water molecules from the film, promotes crystallization, and enables the preparation of organic donor-acceptor charge transfer eutectic self-supporting films on the surface of interdigitated electrodes.

[0019] S4. Preparation of polymer self-supporting films on the surface of organic donor-acceptor charge transfer eutectic self-supporting films: S41. Dissolve 1-100 mg / mL of the polymer in a first specific solvent, and heat at 50-70 °C. oThe mixture is heated and stirred at C for 2-5 hours to obtain a second clear solution; wherein the polymer is methyl methacrylate (PMMA), polystyrene (PS) or polyvinylidene fluoride (PVDF), and the second specific solvent is toluene or dimethylformamide; S42. Place the substrate with interdigitated electrodes and organic donor-acceptor charge transfer eutectic self-supporting film in a culture dish, and then add an appropriate amount of deionized water to the culture dish; wherein, the substrate is flexible polyethylene terephthalate (PET) or polydimethylsiloxane (PDMS), etc. S43. Then, according to the water surface area, use a pipette to continuously drop an appropriate amount of the second clear solution obtained in step S41 from the edge into the petri dish at a speed of 0.01-0.1 mL / min. The second clear solution floats on the water surface and is left to stand for 12-24 hours to allow the solution to completely evaporate. S44. Slowly extract the thin film onto the substrate: then at 70-120°C... o Vacuum annealing at C for 12-24 h is performed to remove dissolved oxygen and water molecules from the film, thereby enabling the preparation of polymer self-supporting films on organic donor-acceptor charge transfer eutectic self-supporting films.

[0020] S5. A 50-200 nm thick metal electrode is deposited on the surface of the polymer self-supporting film by vacuum thermal evaporation as a gate electrode, ultimately obtaining a flexible transistor sensor. The metal electrode can be a gold, silver, or aluminum electrode.

[0021] Specifically, both organic donor-acceptor charge transfer eutectic self-supporting films and polymer self-supporting films are prepared using the water-solution-air interface method, which includes the following steps: S51. Dissolve the raw material in a specific solvent, heat and mix it at a certain temperature for a period of time to obtain a clear solution; S52. Clean the substrate and place the cleaned substrate in a culture dish, then add deionized water to the culture dish. S53. Then, at a certain speed, drop the clear solution into the petri dish and let it stand for a period of time. S54. Finally, annealing is performed to obtain the film corresponding to the current raw material.

[0022] This invention is the first to propose a method for achieving ultrasensitive sensing performance based on weak interfacial intermolecular charge transfer. This invention can obtain various self-supporting single-crystal, polycrystalline, and amorphous thin films, overcoming the substrate dependence of traditional spin-coating methods, and developing novel flexible semiconductor materials and sensing mechanisms for sensing.

[0023] This invention is applicable to the fabrication of any flexible device, and is inexpensive, fast, and can produce large-area devices, thus promoting the fabrication and development of related flexible devices. The flexible sensor of this invention utilizes the characteristic that its charge transfer is easily affected by external fields to achieve sensing applications. It is innovative in terms of mechanism, materials, and the fabrication methods of each thin film layer of the flexible transistor, and plays an important role in promoting the development of tactile sensors and intelligent technologies.

[0024] The beneficial effects of this invention are: 1. This invention designs and prepares an organic donor-acceptor charge transfer eutectic self-supporting thin film, a novel material that can be used in flexible devices; 2. Compared to traditional spin-coating methods, this invention can obtain large-area semiconductor single crystals and polymer self-supporting films with controllable thickness, area, uniformity, and flexibility, which is easy for large-scale industrialization.

[0025] 3. Traditional single-component materials, based on strong intramolecular interactions, have limited deformation and resistance changes due to external forces. The organic donor-acceptor charge transfer eutectic self-supporting thin film of the present invention, based on weak intermolecular charge transfer interactions, achieves force sensing by regulating charge transfer through external forces, resulting in high sensing sensitivity.

[0026] 4. Traditional single-component materials have limited range of physical property regulation; the donor-acceptor composite material proposed in this invention can change the type, ratio, and magnitude of the donor and acceptor, thereby regulating the changes in physicochemical properties, giving the sensor a wider sensing range, and playing an important role in promoting the development of other flexible devices. Attached Figure Description

[0027] Figure 1 The invention proposes an innovative mechanism for force sensing based on weak intermolecular interactions. Figure 2 A schematic diagram illustrating the effect of total surface tension at the water-solution-air interface on film formation; Figure 3 a represents the thin film preparation process; Figure 3 b is a photograph of the thin film on the water surface; Figure 3 c is a photograph of the flexible thin film formed on the substrate; Figure 4 a is a high-resolution transmission electron microscope image of the thin film; Figure 4 b represents P3HT and P3HT-C 60 Comparison of absorption spectra of eutectic thin films; Figure 4 c represents the thickness of the thin film as analyzed by atomic force microscopy; Figure 5a is a schematic diagram of the flexible transistor fabrication process; Figure 5 b is a photograph of each layer of the flexible transistor; Figure 6 a is a test image showing a standard mass weight subjected to uniform pressure; Figure 6 b is the transfer characteristic curve of the transistor; Figure 6 c represents the output characteristic curve of the transistor; Figure 6 d represents the current change characteristic dependent on pressure change without the addition of gate electrodes; Figure 6 e represents the current-voltage curves under different pressures without the addition of gate electrodes; Figure 6 f represents the current variation characteristics under different gate voltages ranging from 10 to 40V. Detailed Implementation

[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0029] The flexible transistor sensor of this invention is a transistor device with flexibility and force sensing capabilities. The semiconductor layer of the flexible transistor sensor is an organic donor-acceptor charge transfer eutectic self-supporting thin film, and the dielectric layer is a polymer self-supporting thin film. There is a relationship between the donor and acceptor in the organic donor-acceptor charge transfer eutectic self-supporting thin film, as shown in the image. Figure 1 The aforementioned weak interaction.

[0030] The embodiments of the present invention are as follows: Example 1: like Figure 3 As shown in a, the preparation of PBTTT-TCNQ charge-transfer eutectic self-supporting thin films mainly involves four steps: (1) Mixing and solution preparation of PBTTT and TCNQ raw materials: Dissolve 10 mg / mL organic donor PBTTT and 1 mg / mL organic acceptor TCNQ in chlorobenzene, 70 o The mixture was heated and stirred at C for 2 hours to obtain a clear solution. (2) Substrate cleaning and placement: The flexible PET substrate is ultrasonically cleaned in deionized water, acetone and isopropanol for 5-10 min respectively, and then cleaned in a plasma cleaner for 5 min to obtain a clean hydrophilic surface. The cleaned substrate is then placed in a culture dish, and 10 mL of deionized water is added to a 20 mL culture dish. (3) Uniform dispersion and film formation of the solution on the water surface: Take 0.5 mL of PBTTT-TCNQ chlorobenzene solution, such as Figure 2 As shown, using a pipette, slowly and continuously drop the solution onto the water surface from the edge at a rate of 0.1 mL / min, allowing the solution to spread. Then, let the solution stand for 12 hours to allow it to completely evaporate and form a uniform film. Figure 3 As shown in b; (4) Slowly extract the thin film onto the substrate: vacuum 120 o Annealing at C for 12 h removes dissolved oxygen and water molecules from the film, promoting crystallization. Finally, a PBTTT-TCNQ charge-transfer eutectic self-supporting film is prepared. Film images are shown below. Figure 3 As shown in c.

[0031] Figure 4 a describes the crystal structure of the precipitated thin film. Figure 4 b. The comparison shows that there is a strong charge transfer interaction between the donor and acceptor in the precipitated film. Figure 4 c indicates that the film thickness is around 160nm and the surface is relatively smooth.

[0032] Example 2: The preparation of PMMA self-supporting films mainly involves four steps: (1) Preparation of PMMA solution: Dissolve 20 mg / mL PMMA in toluene solution, 70 o The mixture was heated and stirred at C for 2 hours to obtain a clear solution. (2) Substrate cleaning and placement: The flexible PET substrate is ultrasonically cleaned in deionized water, acetone and isopropanol for 5-10 min respectively, and then cleaned in a plasma cleaner for 5 min to obtain a clean hydrophilic surface. The cleaned substrate is then placed in a culture dish, and 10 mL of deionized water is added to a 20 mL culture dish. (3) Uniform dispersion and film formation of solution on water surface: Take 0.5 mL of PMMA toluene solution and use a pipette to slowly and continuously drop it onto the water surface from the edge at a speed of 0.1 mL / min, allowing the solution to spread. Then let the solution stand for 12 h until the solution completely evaporates and forms a uniform film. (4) Slowly extract the thin film onto the substrate: vacuum 120 o Annealing at C for 12 h removes dissolved oxygen and water molecules from the film, promotes crystallization, and finally prepares a PMMA-supported film.

[0033] Example 3: like Figure 5 a and Figure 5 As shown in b, a flexible transistor sensor based on an organic donor-acceptor charge transfer eutectic self-supporting thin film is fabricated. The transistor fabrication in this embodiment consists of 5 steps: (1) Substrate cleaning and placement: Immerse the PET substrate in deionized water, acetone or isopropanol and ultrasonically clean for 5-10 minutes, then clean it in a UV-ozone or plasma cleaner for 5-10 minutes to obtain a clean hydrophilic surface. (2) Fabrication of interdigitated electrodes: A 100 nm thick gold electrode was deposited on a cleaned PET substrate by vacuum thermal evaporation using the traditional photolithography method. The electrode width was 100 µm, the electrode length was 1 mm, and the transistor channel width was 100 µm. (3) Preparation of organic donor-acceptor charge transfer eutectic film: 31) Dissolve 10 mg / mL organic donor PBTTT and 1 mg / mL organic acceptor TCNQ in chlorobenzene, 70 o Heat and stir at C for 2 hours to obtain a clear solution. o C. Heat and mix for 2 hours to obtain a clear solution; 32) Place the substrate with interdigitated electrodes in a culture dish, and then add 10 mL of deionized water to the culture dish; 33) Take 0.5 mL of PBTTT-TCNQ chlorobenzene solution, such as Figure 2 As shown, using a pipette, slowly and continuously drop the solution onto the water surface from the edge at a rate of 0.1 mL / min, allowing the solution to spread. Then, let the solution stand for 12 hours to allow it to completely evaporate and form a uniform film. Figure 3 As shown in b; 34) in 70-120 o Vacuum annealing at C for 12-24 h was performed to remove dissolved oxygen and water molecules from the film and promote crystallization. Finally, a PBTTT-TCNQ charge-transfer eutectic self-supporting film was prepared on the interdigitated electrode. Film images are shown below. Figure 3 As shown in c; (4) Preparation of polymer self-supporting films: 41) Dissolve 20 mg / mL PMMA in toluene solution, 70 o C. Heat and mix for 2 h to obtain a clear solution; 42) Place the substrate with interdigitated electrodes and organic donor-acceptor charge transfer eutectic self-supporting film in a petri dish, and add 10 mL of deionized water to the petri dish; 43) Take 0.5 mL of PMMA in toluene solution, and use a pipette to slowly and continuously drop it onto the water surface from the edge at a speed of 0.1 mL / min, allowing the solution to spread. Then let the solution stand for 12 h until the solution completely evaporates to form a uniform film; 44) Vacuum anneal at 70-120°C for 24 h to remove dissolved oxygen and water molecules in the film and promote crystallization. Finally, prepare a PMMA self-supporting film on the organic donor-acceptor charge transfer eutectic film; (5) A 50 nm thick metal electrode is deposited on the surface of the polymer self-supporting film by vacuum thermal evaporation as a gate electrode, ultimately obtaining a flexible transistor sensor, such as... Figure 5 As shown in b.

[0034] The prepared sensor was subjected to the following processes: Figure 6 The pressure test shown in figure a Figure 6 b and Figure 6 c illustrates the transfer and output curves of the flexible transistor, with an on / off ratio reaching 10. 4 Orders in magnitude, surface-mount transistors exhibit better performance; Figure 6 d and Figure 6 e illustrates the current change under applied pressure without a gate electrode, with a response sensitivity of 0.05 kPa. -1 When the applied gate voltage reaches 40 V, its response sensitivity increases to 0.17 kPa. -1 This represents an improvement of more than three times, demonstrating the effective role of the gate effect of surface transistors in enhancing sensing sensitivity.

[0035] This invention enables the creation of flexible transistor devices based on organic donor-acceptor eutectic systems with arbitrary combinations. It overcomes the limitation of traditional single-material strong intramolecular interactions causing insensitivity to resistance changes in force sensing. It yields a variety of flexible, large-area, uniform crystalline and amorphous thin films that can be rapidly fabricated in one step, achieving high-sensitivity force sensing performance. This promotes the development of tactile sensors and has important applications in intelligent fields such as medical intelligence and artificial intelligence robots.

[0036] Those skilled in the art will understand that the above description is merely 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 within the protection scope of the present invention.

Claims

1. A method for preparing an organic donor-acceptor charge transfer eutectic self-supporting thin film, characterized in that, The method includes the following steps: S11. Dissolve the organic donor and the organic acceptor in a first specific solvent, heat and mix them at a certain temperature for a period of time to obtain a first clear solution; then add the antisolvent to obtain a mixed solution; S12. Clean the substrate and place the cleaned substrate in a petri dish, then add deionized water to the petri dish. S13. Then, drop the mixed clear solution into the petri dish at a certain speed and let it stand for a period of time. S14. Finally, annealing is performed to obtain an organic donor-acceptor charge transfer eutectic self-supporting film.

2. The preparation method according to claim 1, characterized in that, The method is specifically as follows: S11. Dissolve an organic donor with a concentration not exceeding 20 mg / mL and an organic acceptor with a concentration not exceeding 20 mg / mL in a first specific solvent, and heat at 50-80 °C. o Heating and stirring at C for 1-5 hours yields a first clear solution; then adding no more than 5 vol% of antisolvent to the first clear solution, sonicating at room temperature for 1-5 minutes, and then sealing and allowing to stand for 5-24 hours yields a mixed solution. S12. Immerse the substrate in deionized water, acetone or isopropanol and ultrasonically clean for 5-10 minutes, then clean it in a UV-ozone or plasma cleaner for 5-10 minutes. Place the cleaned substrate in a petri dish and add deionized water to the petri dish. S13. Then, drop the mixed solution obtained in step S11 into the petri dish at a rate of 0.01-0.1 mL / min and let it stand for 12-24 hours. S14, then at 50-120 o C is vacuum annealed for 2-12 hours to prepare an organic donor-acceptor charge transfer eutectic self-supporting film on the substrate. In step S11, the organic donor is poly(3-thiophene), polyaniline, polyisothioindene, tetrathiofulvalene, pentanebenzene, tetra(dimethylamino)ethylene, or DNA, etc., and the organic acceptor is fullerene pyromellitic tetramethylamine diimide, perylene diimide, anthraquinone, tetrachlorobenzoquinone, tetrafluorop-benzoquinone, or tetracyanoethylene, etc.; the first specific solvent is chlorobenzene or dimethyl sulfoxide; in step S12, the substrate is polyethylene terephthalate, glass, silicon, or sapphire, etc.

3. A method for preparing a polymer self-supporting thin film, characterized in that, The method includes the following steps: S21. Dissolve the polymer in a second specific solvent, heat and mix at a certain temperature for a period of time to obtain a second clear solution; S22. Clean the substrate and place the cleaned substrate in a petri dish, then add deionized water to the petri dish. S23. Then, drop the second clear solution into the petri dish at a certain speed and let it stand for a period of time. S24. Finally, annealing is performed to obtain a polymer self-supporting film.

4. The preparation method according to claim 3, characterized in that, Steps S21-S24 are specifically as follows: S21. Dissolve 1-100 mg / mL of the polymer in a second specific solvent, and heat at 50-70 °C. o The mixture is heated and stirred at temperature C for 2-5 hours to obtain a second clear solution. S22. Immerse the substrate in deionized water, acetone or isopropanol and ultrasonically clean for 5-10 minutes, then clean it in a UV-ozone or plasma cleaner for 5-10 minutes. Place the cleaned substrate in a culture dish and add deionized water to the culture dish. S23. Then, drop the second clear solution obtained in step S21 into the petri dish at a rate of 0.01-0.1 mL / min and let it stand for 12-24 hours. S24, then at 50-120 o A self-supporting polymer film was prepared on the substrate by vacuum annealing at C for 2-12 hours. In step S21, the polymer is methyl methacrylate, polystyrene, or polyvinylidene fluoride, and the second specific solvent is toluene or dimethylformamide; in step S22, the substrate is polyethylene terephthalate, glass, silicon, or sapphire, etc.

5. A flexible transistor sensor based on an organic donor-acceptor charge transfer eutectic self-supporting thin film, the flexible transistor sensor comprising a semiconductor layer and a dielectric layer, characterized in that: The flexible transistor sensor is a transistor device, the semiconductor layer is an organic donor-acceptor charge transfer eutectic self-supporting thin film, and the dielectric layer is a polymer self-supporting thin film.

6. A flexible transistor sensor based on an organic donor-acceptor charge transfer eutectic self-supporting thin film according to claim 5, characterized in that: The organic donor-acceptor charge transfer eutectic self-supporting film is an organic donor-acceptor charge transfer eutectic film containing π electrons. The organic donor is poly(3-thiophene), polyaniline, polyisothioindene, tetrathiofulvalene, pentanebenzene, tetra(dimethylamino)ethylene, or DNA, etc., and the organic acceptor is fullerene, pyromellitic tetramethylamine diimide, perylene diimide, anthraquinone, tetrachlorobenzoquinone, tetrafluorop-benzoquinone, or tetracyanoethylene, etc.; the polymer self-supporting film is a polymethyl methacrylate film, a polystyrene film, or a polyvinylidene fluoride film.

7. A method for fabricating a flexible transistor sensor based on an organic donor-acceptor charge transfer eutectic self-supporting thin film as described in claim 5 or 6, characterized in that, Includes the following steps: S1. Clean the substrate; S2. Metal electrodes are deposited as interdigitated electrodes by vacuum thermal evaporation on the cleaned substrate using photolithography. S3. Prepare an organic donor-acceptor charge transfer eutectic self-supporting thin film on the surface of the interdigitated electrode; S4. Prepare polymer self-supporting films on the surface of organic donor-acceptor charge transfer eutectic self-supporting films; S5. A metal electrode is deposited on the surface of a polymer self-supporting thin film by vacuum thermal evaporation as a gate electrode, and finally a flexible transistor sensor is obtained.

8. The preparation method according to claim 7, characterized in that, The specific steps S1-S2 are as follows: S1. Immerse the substrate in deionized water, acetone or isopropanol and ultrasonically clean for 5-10 minutes, then clean it in a UV-ozone or plasma cleaner for 5-10 minutes. Place the cleaned substrate in a petri dish and add deionized water to the petri dish. S2. Interdigitated electrodes are prepared by vacuum thermal evaporation deposition of metal electrodes on a cleaned substrate using photolithography.

9. The preparation method according to claim 7, characterized in that, Step S3 specifically involves: S31. Dissolve an organic donor with a concentration not exceeding 20 mg / mL and an organic acceptor with a concentration not exceeding 20 mg / mL in a first specific solvent, and heat at 50-80 °C. o Heating and stirring at C for 1-5 hours yields a first clear solution; then adding no more than 5 vol% of antisolvent to the first clear solution, sonicating at room temperature for 1-5 minutes, and then sealing and allowing to stand for 5-24 hours yields a mixed solution. S32. Place the substrate with interdigitated electrodes in a culture dish, and then add deionized water to the culture dish. S33. Then, drop the mixed solution obtained in step S31 into the petri dish at a rate of 0.01-0.1 mL / min and let it stand for 12-24 h. S34, then at 70-120 o C was vacuum annealed for 12-24 h to prepare organic donor-acceptor charge transfer eutectic self-supporting thin films on the surface of interdigitated electrodes; S41. Dissolve 1-100 mg / mL of the polymer in a first specific solvent, and heat at 50-70 °C. o The mixture is heated and stirred at temperature C for 2-5 hours to obtain a second clear solution. S42. Place the substrate with interdigitated electrodes and organic donor-acceptor charge transfer eutectic self-supporting film in a culture dish, and then add deionized water to the culture dish. S43. Then, drop the second clear solution obtained in step S41 into the petri dish at a rate of 0.01-0.1 mL / min and let it stand for 12-24 h. S44, then at 70-120 o Vacuum annealing at C for 12-24 h was performed to prepare a polymer self-supporting film on the organic donor-acceptor charge transfer eutectic self-supporting film.

10. The preparation method according to claim 9, characterized in that: In step S31, the organic donor is poly(3-thiophene), polyaniline, polyisothioindene, tetrathiofulvalene, pentanebenzene, tetra(dimethylamino)ethylene, or DNA, etc., and the organic acceptor is a fullerene pyromellitic tetramethylamine diimide, perylene diimide, anthraquinone, tetrachlorobenzoquinone, tetrafluorop-benzoquinone, or tetracyanoethylene, etc.; the first specific solvent is chlorobenzene or dimethyl sulfoxide; in step S32, the substrate is polyethylene terephthalate or polydimethylsiloxane; in step S41, the polymer is methyl methacrylate, polystyrene, or polyvinylidene fluoride, and the second specific solvent is toluene or dimethylformamide; in step S42, the substrate is polyethylene terephthalate or polydimethylsiloxane, etc.

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