Self-powered gate organic field effect transistor based on hydro-voltaic effect and preparation method of self-powered gate organic field effect transistor

Abstract

The invention discloses a self-powered gate organic field effect transistor based on a water photovoltaic effect and a preparation method thereof, and is characterized in that the self-powered gate organic field effect transistor sequentially comprises a water photovoltaic gate, an insulating layer, an organic semiconductor layer, a source electrode and a drain electrode from bottom to top, and the source electrode and the drain electrode are arranged on the organic semiconductor layer. Wherein the water photovoltaic grid electrode sequentially comprises a flexible substrate, a bottom electrode, a composite film and a top electrode from bottom to top; the water photovoltaic grid composite film comprises a PVA / LiCl polymer film and a plurality of layers of GO films; and the top electrode is arranged on the PVA / LiCl film. The bottom electrode of the water photovoltaic grid electrode is connected with the source electrode through a wire, so that a voltage difference is generated between the grid electrode and the source electrode, a carrier is induced at the interface of the insulating layer and the semiconductor layer, and a plurality of water photovoltaic grid electrodes can be vertically overlapped and connected in series to increase output voltage on the existing device structure according to actual conditions; the source electrode and the drain electrode are connected with an external power supply, and voltage is applied, so that the transistor works normally.

Description

Technical Field

[0001] The present invention relates to the field of semiconductors and flexible electronics, and in particular to a self-powered gate organic field effect transistor based on the hydrovoltaic effect and a preparation method thereof. Background Art

[0002] With the development of Internet of Things technology, it has become a very challenging task to provide long-term power supply to each terminal of the Internet of Things. The current method of using energy storage batteries to power each terminal greatly reduces the data transmission distance and power due to the limitation of battery life, and the scope of application is also limited. Collecting energy (light energy, mechanical energy, thermal energy, etc.) in the environment is expected to replace the current energy supply method. In recent years, hydrovoltaic power generation technology that uses water evaporation and water vapor in the air to generate electricity has attracted widespread attention. Due to the spontaneity of evaporation and the small geographical constraints, hydrovoltaic generators can generate electricity for a long time and continuously without the need for mechanical energy input. They are ideal sources of green energy. Therefore, they have broad application prospects in the fields of flexible circuits, biosensors, self-driven sensors, wearable electronic devices, etc., and are expected to be used to construct new, self-driven electronic devices. As a basic component of flexible electronics, organic field-effect transistors have broad application prospects in the fields of flexible displays, wearable and implantable electronics, and their realization of self-powered gate regulation is of great significance to their development. Summary of the invention

[0003] The present invention provides a self-powered gate organic field effect transistor based on the hydrovoltaic effect and a preparation method thereof, which utilizes water resources in the environment to generate electricity to provide a gate voltage for the organic field effect transistor, thereby solving the problem in the prior art that an external power supply is required to provide the gate voltage, and laying a good technical foundation for the development of organic field effect transistors in the fields of human-computer interaction, the Internet of Things, and electronic skin.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is: A self-powered gate organic field effect transistor based on the hydrovoltaic effect, comprising a hydrovoltaic gate, an insulating layer, an organic semiconductor layer, and a source and drain electrode arranged on the organic semiconductor layer, which are sequentially stacked from bottom to top; the hydrovoltaic gate sequentially comprises: a flexible substrate, a bottom electrode, a composite film, and a top electrode from bottom to top; wherein the composite film comprises a PVA / LiCl polymer film and a multilayer GO film, wherein each layer of the GO film is sequentially stacked on the bottom electrode from bottom to top, and the concentration of GO in each layer of the GO film increases in a gradient from bottom to top, the PVA / LiCl polymer film is arranged on the topmost GO film, and the top electrode is arranged on the PVA / LiCl polymer film; The top electrode is directly in contact with the insulating layer as a gate, and the bottom electrode is connected to the source electrode through a wire to generate a voltage difference between the gate and the source electrode, and to induce carriers at the interface between the insulating layer and the semiconductor layer. According to actual conditions, multiple hydrovoltaic gate electrodes can be vertically stacked and connected in series on the existing device structure to increase the output voltage; the source electrode and the drain electrode are connected to an external power supply and voltage is applied to make the transistor work normally; During use, the composite film in the hydrovoltaic grid absorbs water and ionizes hydrogen ions. The hydrogen ions move in a directional manner due to the concentration gradient, thereby generating a voltage difference between the bottom electrode and the top electrode.

[0005] Furthermore, the flexible substrate material of the hydrovoltaic gate is a flexible PET material, or a flexible PDMS material, or a flexible PI material.

[0006] Furthermore, the bottom electrode material of the hydrovoltaic gate is ITO, Al, or AgNW, CNT, graphene, etc.

[0007] Furthermore, the top electrode material is AgNW, CNT or graphene.

[0008] Furthermore, the PVA / LiCl polymer film of the hydrovoltaic gate is obtained by spin coating a PVA / LiCl mixed solution on the top GO film and heating it, wherein the PVA / LiCl mixed solution is a mixture of 100 mg / ml PVA solution and 1 mol / L LiCl solution in a volume ratio of 2:1.

[0009] Furthermore, the composite film of the hydrovoltaic gate includes four layers of GO films, the GO concentrations in the two lower GO films are the same, the GO concentrations in the two upper GO films are the same, and the GO concentrations in the two lower GO films are less than the GO concentrations in the two upper GO films.

[0010] Furthermore, the concentration of GO in the two lower GO thin films of the hydrovoltaic gate composite film is 0.5 mg / mL, and the concentration of GO in the two upper GO thin films is 1 mg / ml.

[0011] Furthermore, the insulating layer is an organic polymer insulating material (such as PVA, PVP or hydrogel, etc.) with a thickness of 400 nm to 1500 nm or an inorganic insulating layer material (such as aluminum oxide or silicon dioxide, etc.) with a thickness of 100 nm to 300 nm.

[0012] Furthermore, the semiconductor layer is an organic semiconductor material with a thickness of 10 nm to 50 nm; the source and drain electrodes are selected from electrode materials with Fermi level matching according to the energy level structure of the semiconductor layer, such as gold, silver or aluminum, and the electrode film thickness is 30 nm to 100 nm.

[0013] A method for preparing the above-mentioned self-powered gate organic field effect transistor based on the hydrovoltaic effect comprises the following steps: Step 1: prepare a bottom electrode on a flexible substrate, and select whether to perform plasma etching on the bottom electrode according to the electrode material; Step 2, sequentially coating multiple layers of GO solution on the bottom electrode, and performing heating and annealing treatment after coating each layer of GO solution, thereby forming a multilayer GO film; Step 3, spin coating a PVA / LiCl mixed solution on the top GO film, and then heat treating to form a PVA / LiCl film; Step 4: Prepare a top electrode on the PVA / LiCl film by thermal evaporation, magnetron sputtering or spraying; Step 5: Prepare an insulating layer on the top electrode by spin coating, scraping or atomic layer deposition; Step 6: preparing an organic semiconductor layer on the surface of the insulating layer by using a surface self-assembly process or a spin coating process; Step 7: Prepare the source and drain by thermal evaporation or spraying in combination with a mask.

[0014] Furthermore, in step 1, the flexible substrate with the bottom electrode can be purchased commercially or prepared by oneself. Taking PDMS as an example, the specific process of preparing it by oneself is as follows: The PDMS stock solution and the cross-linking agent were stirred and blended in a mass ratio of 10:1 until dense bubbles were generated, and then the mixed solution was placed in a vacuum box at 0.1 Pa for 20 min to remove bubbles to obtain a transparent bubble-free liquid. The PDMS liquid was spin-coated or scraped on a rigid substrate, and the prepared film was placed on a heating table for annealing at 60 °C for 60 min to obtain a semi-solidified PDMS film. A conductive solution was sprayed on the surface of the PDMS film, and the sprayed film was placed on a heating table for annealing at 100 °C for 10 min, and then the entire substrate was placed on a heating table for annealing at 60 °C for 120 min to completely solidify the PDMS film, thereby obtaining a flexible substrate with a bottom electrode.

[0015] Furthermore, in step 2, the temperature of the heating annealing treatment is 100° C., and the time of the heating annealing treatment is 20 minutes.

[0016] Furthermore, in step 3, the heating treatment temperature is 80° C., and the heating treatment time is 30 min.

[0017] Furthermore, in step 4, the 5 mg / ml Ag NW stock solution was diluted with isopropanol at a volume ratio of 1:20, and then sprayed to prepare the Ag NW film, followed by annealing at 110 °C for 5 min.

[0018] Furthermore, in step 5, a 50 mg / ml PVA solution was spin-coated on the top electrode surface at a speed of 1500 rpm, and after spin-coating for 60 s, the film was annealed on a heating platform at 50° C. for 60 min.

[0019] Furthermore, in step 6, the organic semiconductor layer IDTBT is prepared on the surface of the insulating layer by spin coating at a rotation speed of 1000 rpm for 60 s, and annealed at room temperature at 120° C. for 10 min after the spin coating.

[0020] Furthermore, in step 7, a source electrode and a drain electrode are deposited on the surface of the semiconductor layer by thermal evaporation in combination with a mask. The material is gold with a thickness of 50 nm. The aspect ratio of the electrode channel is 1000 um:30 um.

[0021] Compared with the prior art, the present invention has the following advantages: The water-based gate is used to convert moisture in the environment into electrical energy, and a potential difference is generated between the gate and the source connected to it to replace the gate voltage applied by the external power supply. Carriers are induced at the interface between the semiconductor layer and the insulating layer to achieve the gate voltage regulation function, reducing the dependence of organic field-effect transistors on external power supplies. By optimizing the device structure and realizing self-powered gate voltage regulation, it provides new ideas for the development of technologies such as human-computer interaction, the Internet of Things, biomedicine, and flexible wearable electronics, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the device structure of an embodiment of the present invention.

[0023] Figure 2 It is a schematic diagram of the structure of the overall device after multiple hydrovoltaic gates of the device according to an embodiment of the present invention are connected in series.

[0024] Figure 3 It is a schematic diagram of the structure of the water-voltage grid according to an embodiment of the present invention.

[0025] Figure 4 It is a process flow chart of the preparation of the hydrovoltaic grid according to an embodiment of the present invention.

[0026] Figure 5 It is a working principle diagram of the water-voltage grid according to an embodiment of the present invention.

[0027] Figure 6 It is a graph showing the power supply characteristic curve of a single water-voltage grid in an embodiment of the present invention. DETAILED DESCRIPTION

[0028] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0029] like Figure 1As shown, this embodiment discloses a self-powered gate organic field effect transistor device based on the hydrovoltaic effect, comprising a hydrovoltaic gate 1, an insulating layer 2, an organic semiconductor layer 3, a source electrode 4 and a drain electrode 5 disposed on the organic semiconductor layer. The bottom electrode of the hydrovoltaic gate and the source electrode are connected by a wire, and the source electrode 4 and the drain electrode 5 are connected to an external power source 6.

[0030] Figure 2 7 is a schematic diagram of the overall device structure consisting of multiple water-voltage gates connected in series, and 7 is a group of multiple water-voltage gates connected in series.

[0031] like Figure 3 As shown, the hydrovoltaic grid includes a flexible substrate 1, a bottom electrode 2, a composite film, and a top electrode 4. The bottom electrode 2 is disposed on the flexible substrate 1, the composite film is disposed on the bottom electrode, and the top electrode 4 is disposed on the composite film. The bottom electrode 2 is used as a positive electrode, and the top electrode 4 is used as a negative electrode. The bottom electrode 2 and the top electrode 4 are respectively connected to an external signal acquisition device.

[0032] The composite film of the water-voltaic grid of this embodiment includes a PVA / LiCl polymer film 3.1 and a multi-layer GO film. In the composite film, each layer of GO film is stacked on the bottom electrode 2 from bottom to top, that is, the first layer of GO film is arranged on the bottom electrode 2, the second layer of GO film is arranged on the first layer of GO film, the third layer of GO film is arranged on the second layer of GO film, and so on, the n-1th layer of GO film is arranged on the n-2th layer of GO film, and the nth layer of GO film is arranged on the n-1th layer of GO film, n≥2. And the concentration of GO in each layer of GO film increases gradually from bottom to top.

[0033] Specific as Figure 3 As shown, in the composite film of the hydrovoltaic gate of this embodiment, there are four layers of GO film, among which the bottom GO film 3.2 is arranged on the bottom electrode 2, the next bottom GO film 3.3 is arranged on the bottom GO film 3.2, the next top GO film 3.4 is arranged on the next bottom GO film 3.3, and the top GO film 3.5 is arranged on the next top GO film 3.4. The concentration of GO in the two bottom GO films 3.2 and 3.3 is the same, both 0.5 mg / mL, and the concentration of GO in the two top GO films 3.4 and 3.5 is the same, both 1 mg / ml.

[0034] In the composite film of the hydrovoltaic gate of this embodiment, the PVA / LiCl polymer film 3.1 is obtained by spin coating a PVA / LiCl mixed solution on the top GO film 3.5 and heating it, wherein the PVA / LiCl mixed solution is a 100 mg / ml PVA solution and a 1 mol / L LiCl solution mixed in a volume ratio of 2:1. The top electrode 4 is disposed on the PVA / LiCl polymer film 3.1, thereby forming a complete hydrovoltaic gate.

[0035] In this embodiment, the material of the flexible substrate of the hydrovoltaic gate is a flexible PET material, or a flexible PDMS material, or a flexible PI material.

[0036] In this embodiment, the material of the bottom electrode of the water-repellent gate is ITO, Al, or AgNW, CNT, graphene, etc.

[0037] In this embodiment, the top electrode material of the hydrovoltaic gate is AgNW, CNT or graphene.

[0038] In this embodiment, the insulating layer is an organic polymer insulating material (such as PVA, PVP or hydrogel) with a thickness of 400 nm to 1500 nm or an inorganic insulating layer material (such as aluminum oxide or silicon dioxide) with a thickness of 100 nm to 300 nm.

[0039] In this embodiment, the semiconductor layer is an organic semiconductor material with a thickness of 10 nm to 50 nm; the source and drain electrodes are selected from electrode materials with Fermi level matching according to the energy level structure of the semiconductor layer, such as gold, silver or aluminum, and the electrode film thickness is 30nm~100nm.

[0040] Figure 4 Shown is a process flow chart of preparing the hydrovoltaic grid in this embodiment.

[0041] In the following embodiment, a method for preparing the self-powered gate organic field effect transistor based on the hydrovoltaic effect is described by taking a flexible PET material as a hydrovoltaic gate flexible substrate 1 material, an indium tin oxide ITO material as a bottom electrode 2 material, an AgNW as a top electrode 4 material, and a hydrovoltaic gate composite film having four layers of GO film as an example. The specific method includes the following steps: Step 1. Cut the purchased flexible substrate PET (flexible substrate 1) with ITO conductive film (bottom electrode 2) into the required size and fix it on the rigid substrate with double-sided tape. Then place the fixed PET / ITO substrate as a whole in a plasma etcher with the RF power set to 20 W, introduce oxygen for plasma etching for 8 to 15 minutes, and then take it out for use.

[0042] Step 2: prepare graphene oxide solution. The graphene oxide solution was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. The graphene oxide solution was configured to be a 0.5 mg / ml GO solution and a 1 mg / ml GO solution for standby use.

[0043] PI tapes of different sizes (the widths of the PI tapes used were 0.5 cm and 1 cm, respectively) were pasted on the surface of the ITO conductive film to construct an area of ​​a certain area to be dripped with the solution.

[0044] Each layer of GO film was prepared by drop coating: first, 200 μL of 0.5 mg / mL GO solution was sucked by a handheld pipette and dropped on the area to be dripped. Then, the ITO conductive film and flexible PET substrate dripped with GO solution were placed on a heating table at 100 °C for heating and annealing for 20 min to form a uniform bottom GO film 3.2; then, 200 μL of 0.5 mg / mL GO solution was dripped on the bottom GO film 3.2, and then the whole was placed on a heating table at 100 °C for heating and annealing for 20 min to form a uniform second-lower GO film 3.3. Then, 200 μL of GO solution with a concentration of 1 mg / mL was drop-coated on the second lower GO film 3.3, and then the whole was placed on a heating table at 100 °C for heating and annealing for 20 min to form a uniform second upper GO film 3.4; finally, 200 μL of GO solution with a concentration of 1 mg / mL was drop-coated on the second upper GO film 3.4, and then the whole was placed on a heating table at 100 °C for heating and annealing for 20 min to form a uniform uppermost GO film 3.5.

[0045] Among the four layers of GO films thus obtained, the GO concentrations in the bottom GO film 3.2 and the next bottom GO film 3.3 are low (both are 0.5 mg / mL), and the GO concentrations in the next top GO film 3.4 and the top GO film 3.5 are high (both are 1 mg / mL), thereby obtaining GO films with different concentration gradients.

[0046] Step 3: First, prepare the PVA / LiCl mixed solution as follows: Take 1.8 g of polyvinyl alcohol powder (PVA) and 18 mL of deionized water and mix them into a glass sample bottle. Place the glass sample bottle on a stirring hot plate (heating temperature set to 90 °C, speed set to 1500 r / min) and heat and stir for 2 h. When the PVA solute is completely dissolved, a PVA aqueous solution with a concentration of 100 mg / mL is obtained. Let it stand at room temperature to cool for use. Prepare a 1 mol / L LiCl solution and let it stand at room temperature for use. Prepare a PVA / LiCl mixed solution by mixing 100 mg / ml PVA solution and 1 mol / L LiCl solution in a volume ratio of 2:1. For example, 2 mL of a PVA solution with a concentration of 100 mg / mL and 1 mL of a LiCl solution with a concentration of 1 mol / L, respectively, add the LiCl solution dropwise to the PVA aqueous solution, stir magnetically until the solution is mixed evenly, and let it stand at room temperature for use.

[0047] Then, the PVA / LiCl mixed solution was spin-coated on the topmost GO film 3.5 with a GO concentration of 1 mg / ml by spin coating. The spin coating speed was 1000 r / min, the acceleration was 500 rmp / s, and the spin coating time was 60 s.

[0048] Finally, the flexible PET substrate with the composite film and the ITO conductive film was placed on a heating table at 80 °C for 30 min to form a uniform PVA / LiCl polymer film 3.1 on the top GO film 3.5. The composite film composed of the PVA / LiCl polymer film 3.1 and the four layers of GO film serves as the functional layer of the hydrovoltaic gate.

[0049] Step 4: dilute 5 mg / ml Ag NW stock solution with isopropanol in a volume ratio of 1:20, and then spray-coat the AgNW film on the PVA / LiCl polymer film 3.1, followed by annealing at 110°C for 5 min, thereby completing the preparation of the hydrovoltaic gate.

[0050] Step 5: Spin coat a 50 mg / ml PVA solution on the top electrode surface at a speed of 1500 rpm. After spin coating for 60 seconds, place the film on a heating platform at 50° C. and anneal for 60 minutes.

[0051] Step 6: The organic semiconductor layer IDTBT was prepared on the surface of the insulating layer by spin coating at a rotation speed of 1000 rpm for 60 s. After the spin coating, the layer was annealed at room temperature at 120° C. for 10 min.

[0052] Step 7: Use thermal evaporation in combination with a mask to evaporate the source and drain on the surface of the semiconductor layer. The material is gold, the thickness is 50 nm, and the aspect ratio of the electrode channel is 1000 um:30 um, thereby completing the preparation of the self-powered gate organic field-effect transistor based on the hydrovoltaic effect.

[0053] like Figure 5 As shown in the figure, the working principle of the water-voltaic gate of this embodiment is as follows: after the PVA / LiCl film absorbs water, the water penetrates into the GO film, and the GO film absorbs water and ionizes hydrogen ions. Since the functional film has a certain thickness, there is a gradient in the distribution of water molecules, which makes the hydrogen ion concentration gradient appear inside the functional layer, prompting the directional movement of hydrogen ions (moving from high concentration to low concentration), thereby forming a potential difference between the bottom electrode and the top electrode, and finally generating an electrical signal. When the humidity decreases, the hydrogen ion concentration at the bottom is higher than that at the top, prompting the hydrogen ions to move from the bottom to the top and recombine with the anions inside the film, and finally returning to the initial state.

[0054] Figure 6 The figure shows the power supply characteristic curve after the water grid absorbs water. Figure 6 It can be seen that the single hydrovoltaic gate device prepared in this embodiment has good cycle stability and good humidity power supply performance when the relative humidity is 75% and the temperature is 27°C (single device, device area is 1.5 cm 2 Can generate a voltage of around ~1.0 V).

[0055] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. The embodiments described in the present invention are merely descriptions of the preferred embodiments of the present invention, and do not limit the concept and scope of the present invention. The various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction, and such combinations should also be regarded as the contents disclosed in the present disclosure as long as they do not violate the concept of the present invention. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0056] The present invention is not limited to the specific details of the above-mentioned embodiments. Within the technical concept of the present invention and without departing from the design concept of the present invention, various modifications and improvements made to the technical solution of the present invention by technical personnel in this field should fall within the protection scope of the present invention. The technical contents for which protection is sought in the present invention have been fully recorded in the claims.

Claims

1. A self-powered gate organic field effect transistor based on the hydrovoltaic effect, characterized in that: It includes a hydrovoltaic gate, an insulating layer, an organic semiconductor layer, and a source and drain electrode arranged on the organic semiconductor layer, which are stacked in sequence from bottom to top; The hydrovoltaic grid includes, from bottom to top, a flexible substrate, a bottom electrode, a composite film, and a top electrode; wherein the composite film includes a PVA / LiCl polymer film and a multilayer GO film, each layer of the GO film is stacked on the bottom electrode from bottom to top, and the concentration of GO in each layer of the GO film increases gradually from bottom to top, the PVA / LiCl polymer film is arranged on the topmost GO film, and the top electrode is arranged on the PVA / LiCl polymer film; The top electrode is directly in contact with the insulating layer as a gate, and the bottom electrode is connected to the source electrode through a wire to generate a voltage difference between the gate and the source electrode, and to induce carriers at the interface between the insulating layer and the semiconductor layer. According to actual conditions, multiple hydrovoltaic gate electrodes can be vertically stacked and connected in series on the existing device structure to increase the output voltage; the source electrode and the drain electrode are connected to an external power supply and voltage is applied to make the transistor work normally; During use, the composite film in the hydrovoltaic grid absorbs water and ionizes hydrogen ions. The hydrogen ions move in a directional manner due to the concentration gradient, thereby generating a voltage difference between the bottom electrode and the top electrode.

2. A self-powered gate organic field effect transistor based on the hydrovoltaic effect according to claim 1, characterized in that: The flexible substrate material of the water-phase gate is a flexible PET material, or a flexible PDMS material, or a flexible PI material; the bottom electrode material of the water-phase gate is ITO, or Al, or AgNW, CNT, or graphene; the top electrode material of the water-phase gate is AgNW, or CNT, or graphene.

3. The self-powered gate organic field effect transistor based on the hydrovoltaic effect according to claim 1, characterized in that: The PVA / LiCl polymer film of the hydrovoltaic gate is obtained by spin coating a PVA / LiCl mixed solution on the top GO film and heating it, wherein the PVA / LiCl mixed solution is obtained by blending 100 mg / ml PVA solution and 1 mol / L LiCl solution in a volume ratio of 2:

1.

4. A self-powered gate organic field effect transistor based on the hydrovoltaic effect as claimed in claim 1, characterized in that: The composite film of the hydrovoltaic gate includes four layers of GO films, the GO concentrations in the two lower GO films are the same, the GO concentrations in the two upper GO films are the same, and the GO concentrations in the two lower GO films are less than the GO concentrations in the two upper GO films.

5. The self-powered gate organic field effect transistor based on the hydrovoltaic effect according to claim 4, characterized in that: The concentration of GO in the two lower GO thin films of the hydrovoltaic gate composite film is 0.5 mg / mL, and the concentration of GO in the two upper GO thin films is 1 mg / ml.

6. The self-powered gate organic field effect transistor based on the hydrovoltaic effect according to claim 1, characterized in that: The insulating layer is an organic polymer insulating material with a thickness of 400 nm to 1500 nm, or an inorganic insulating layer material with a thickness of 100 nm to 300 nm.

7. The self-powered gate organic field effect transistor based on the hydrovoltaic effect according to claim 1, characterized in that: The semiconductor layer is an organic semiconductor material with a thickness of 10 nm to 50 nm; the source and drain electrodes are selected from electrode materials with Fermi level matching according to the energy level structure of the semiconductor layer, and the thickness of the electrode film is 30 nm to 100 nm.

8. A method for preparing a self-powered gate organic field effect transistor based on the hydrovoltaic effect as claimed in any one of claims 1 to 7, characterized in that: The following steps are involved: Step 1: prepare a bottom electrode on a flexible substrate, and select whether to perform plasma etching on the bottom electrode according to the electrode material; Step 2, sequentially coating multiple layers of GO solution on the bottom electrode, and performing heating and annealing treatment after coating each layer of GO solution, thereby forming a multilayer GO film; Step 3, spin coating a PVA / LiCl mixed solution on the top GO film, and then heat treating to form a PVA / LiCl film; Step 4: Prepare a top electrode on the PVA / LiCl film by thermal evaporation, magnetron sputtering or spraying; Step 5: Prepare an insulating layer on the top electrode by spin coating, scraping or atomic layer deposition; Step 6: preparing an organic semiconductor layer on the surface of the insulating layer by using a surface self-assembly process or a spin coating process; Step 7: Prepare the source and drain by thermal evaporation or spraying in combination with a mask.

9. The method for preparing a self-powered gate organic field effect transistor based on the hydrovoltaic effect according to claim 8, characterized in that: In step 1, the specific process of preparing the flexible substrate with the bottom electrode in the hydrovoltaic grid is as follows: The PDMS stock solution and the cross-linking agent were stirred and blended in a mass ratio of 10:1 until dense bubbles were generated, and then the evenly mixed solution was placed in a vacuum box at 0.1 Pa and allowed to stand for 20 min to remove bubbles to obtain a transparent bubble-free liquid; the PDMS liquid was spin-coated or scraped on a rigid substrate, and the prepared film was placed on a heating table and annealed at 60 °C for 60 min to obtain a semi-solidified PDMS film, and a conductive solution was sprayed on the surface of the PDMS film, and the sprayed film was placed on a heating table and annealed at 100 °C for 10 min, and then the entire substrate was placed on a heating table and annealed at 60 °C for 120 min to allow the PDMS film to completely solidify, thereby obtaining a flexible substrate with a bottom electrode.

10. The method for preparing a self-powered gate organic field effect transistor based on the hydrovoltaic effect according to claim 8, characterized in that: In step 2, the temperature of the heating annealing treatment is 100°C, and the time of the heating annealing treatment is 20 min; in step 3, the temperature of the heating treatment is 80°C, and the time of the heating treatment is 30 min.

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