Multifunctional synaptic transistor with organic ternary heterojunction coupling structure and manufacturing method thereof

Abstract

This invention discloses a multifunctional synaptic transistor with an organic ternary heterocoupled structure and its fabrication method, belonging to the field of organic optical synaptic transistors. It includes electrodes and, from bottom to top, a substrate, a gate dielectric layer, and an organic PN junction. The organic PN junction includes an N-type organic semiconductor layer and a P-type organic semiconductor layer stacked on the N-type organic semiconductor layer. A chiral COF layer with a smaller area than the P-type organic semiconductor layer is disposed on the P-type organic semiconductor layer. The electrodes include a source and a drain, both of which are in contact with both the chiral COF layer and the P-type organic semiconductor layer. By inputting information via optical pulses, the photoelectric response enhancement effect formed by the ternary heterocoupled structure can be utilized to collect, process, and store polarization and multi-wavelength photoelectric information. This achieves efficient integration of multiple functions such as circularly polarized light recognition, wide-spectrum response, and bidirectional synapsis, providing a new solution for compact intelligent vision systems.

Description

Technical Field

[0001] This invention relates to a multifunctional synaptic transistor with an organic ternary heterocoupled structure and its fabrication method, belonging to the field of organic optical synaptic transistors. Background Technology

[0002] Bionic vision technology, as a cutting-edge discipline integrating biological mechanisms and optoelectronic engineering, is leading a revolutionary breakthrough in next-generation intelligent sensing systems. In recent years, organic bionic vision systems, with their unique functional tunability, excellent flexibility, significant cost advantages, and lightweight characteristics, have become one of the most promising directions in bionic vision research. Of particular note is the excellent compatibility of organic materials with flexible substrates and their inherent advantages in large-scale fabrication, which has opened up unprecedented development space for diverse application scenarios such as wearable smart devices, high-precision machine vision, next-generation intelligent sensors, precision medical assistance, natural human-computer interaction, intelligent security monitoring, and autonomous driving. However, existing research shows that traditional organic synaptic transistors still have significant shortcomings in accurate circular polarization state recognition, wide-spectrum high-efficiency response, and multifunctional system integration, which greatly limits their practical application performance in complex environments. Summary of the Invention

[0003] To overcome the shortcomings of the prior art, the present invention provides a multifunctional synaptic transistor with an organic ternary heterocoupled structure and a method for fabricating the same, which can simultaneously possess bidirectional synaptic behavior, circularly polarized light-sensitive synaptic behavior, and broadband synaptic response behavior.

[0004] The technical solution adopted by this invention to solve its technical problem is:

[0005] In a first aspect, this application provides a multifunctional synaptic transistor with an organic ternary heterocoupled structure, comprising electrodes and, from bottom to top, a substrate, a gate dielectric layer, and an organic PN junction. The organic PN junction comprises an N-type organic semiconductor layer and a P-type organic semiconductor layer stacked on the N-type organic semiconductor layer. A chiral COF layer with an area smaller than that of the P-type organic semiconductor layer is disposed on the P-type organic semiconductor layer. The electrodes comprise a source and a drain, both of which are in contact with both the chiral COF layer and the P-type organic semiconductor layer.

[0006] The multifunctional synaptic transistor with an organic ternary heterocoupled structure provided in this application is expected to solve the key challenges of multifunctional integration and performance optimization in current biomimetic vision systems by constructing an organic ternary heterocoupled structure. By independently optimizing the chiral optical properties of the chiral COF (covalent organic framework) and the charge transport performance of the two-dimensional organic single crystal (the N-type organic semiconductor layer and the P-type organic semiconductor layer are two-dimensional organic single crystals), the bottleneck of the mutual constraint between the chiral response and electrical performance of traditional single materials is broken. This significantly improves the current asymmetry factor of the device while maintaining excellent photoelectric response characteristics. The chiral COF layer is located on top, which can obtain better light absorption effect.

[0007] Furthermore, the material of the chiral COF layer is R-TpPa-1-COF or S-TpPa-1-COF.

[0008] The rigid framework of this material reduces the interference of molecular vibrations on the light response signal, enhances the stability of circularly polarized light recognition, and has excellent chemical stability, which is beneficial to extending its service life.

[0009] Furthermore, the material of the P-type organic semiconductor layer is DTT-8, BTBT-T7, or Ph-BTBT-10.

[0010] These materials exhibit high energy level matching with R-TpPa-1-COF or S-TpPa-1-COF, enabling rapid transfer of photogenerated holes from the chiral COF layer to the P-type layer and reducing charge recombination losses. While maintaining high circular polarization recognition sensitivity, the device further enhances photoelectric response speed and stability, strengthening the synergistic effect of chiral recognition and charge transport.

[0011] Furthermore, the material of the N-type organic semiconductor layer is TFT-CN, PDIF-CN2, or CMUT.

[0012] These materials are matched with the energy levels of preferred P-type organic semiconductors. Through energy level matching and absorption band complementarity, the devices can achieve high responsivity over a wide wavelength range and also have bidirectional photoresponse capability.

[0013] Furthermore, the thickness of the chiral COF layer is 10nm~100nm, the thickness of the P-type organic semiconductor layer is 1nm~50nm, and the thickness of the N-type organic semiconductor layer is 1nm~50nm.

[0014] These thickness ranges achieve a high-performance balance by optimizing light absorption, charge transport, and interface coupling. At this thickness, chiral COF layers are beneficial for enhancing the response to circularly polarized light, but excessive thickness increases carrier transport paths, leading to a decrease in mobility.

[0015] Secondly, this application provides a method for fabricating a multifunctional synaptic transistor with an organic ternary heterocoupled structure, comprising the following steps:

[0016] A gate dielectric layer is prepared on the substrate surface;

[0017] An organic PN junction is fabricated on the gate dielectric layer, the organic PN junction comprising an N-type organic semiconductor layer and a P-type organic semiconductor layer stacked on the N-type organic semiconductor layer;

[0018] A chiral COF layer is fabricated on the p-type organic semiconductor layer, wherein the area of ​​the chiral COF layer is smaller than that of the p-type organic semiconductor layer;

[0019] An electrode is fabricated on the p-type organic semiconductor layer that simultaneously contacts the p-type organic semiconductor layer and the chiral COF layer. The electrode includes a source and a drain.

[0020] Optionally, the step of fabricating an organic PN junction on the gate dielectric layer includes:

[0021] Prepare an N-type organic semiconductor solution using the first volatile solvent;

[0022] The N-type organic semiconductor solution is dropped onto a first liquid phase substrate, and an N-type organic semiconductor thin film is obtained after the first volatile solvent evaporates.

[0023] The N-type organic semiconductor thin film is transferred onto the gate dielectric layer to serve as the N-type organic semiconductor layer;

[0024] Prepare a p-type organic semiconductor solution using a second volatile solvent;

[0025] The P-type organic semiconductor solution is dropped onto a second liquid phase substrate, and a P-type organic semiconductor thin film is obtained after the second volatile solvent evaporates.

[0026] The P-type organic semiconductor thin film is transferred onto the N-type organic semiconductor layer to form the P-type organic semiconductor layer.

[0027] Optionally, the step of fabricating an organic PN junction on the gate dielectric layer includes:

[0028] Prepare a mixed solution containing both N-type and P-type organic semiconductors, using a third type of volatile solvent; then treat the mixed solution by one of the following two methods:

[0029] The first method involves dropping the mixed solution onto a third liquid phase substrate. After the third volatile solvent evaporates, a layered and stacked bilayer film is obtained, comprising an N-type organic semiconductor film and a P-type organic semiconductor film. The bilayer film is then transferred onto the gate dielectric layer with the N-type organic semiconductor film facing the gate dielectric layer to obtain the organic PN junction.

[0030] The second method involves coating the mixed solution onto the gate dielectric layer, and obtaining the PN junction after the third volatile solvent evaporates.

[0031] Furthermore, in the mixed solution, the concentration of the N-type organic semiconductor is greater than the concentration of the P-type organic semiconductor.

[0032] Optionally, the step of preparing a chiral COF layer on the p-type organic semiconductor layer includes:

[0033] A precursor solution was prepared by dissolving 2,4,6-tricarboxymethyl phloroglucinol, p-phenylenediamine, and a chiral inducing agent in dichloromethane. The chiral inducing agent was S-1-phenylethylamine or R-1-phenylethylamine. The precursor solution was diluted with chlorobenzene and then dropped onto the surface of deionized water. After standing, a chiral COF film was obtained at the gas-liquid interface. The chiral COF film was then transferred onto the p-type organic semiconductor layer to obtain the chiral COF layer.

[0034] The beneficial effects of this invention are: the multifunctional synaptic transistor of the organic ternary heterocoupled structure of this invention can acquire, process and store polarization and multi-wavelength photoelectric information by using the photoelectric response enhancement effect formed by the ternary heterocoupled structure to input information through light pulses, thereby realizing the efficient integration of multiple functions such as circularly polarized light recognition, wide spectrum response and bidirectional synapse, and providing a new solution for compact intelligent vision systems.

[0035] Other features and advantages of this application will be set forth in the following description and will be apparent in part from the description or may be learned by practicing the application. The objectives and other advantages of this application may be realized and obtained by means of the structures particularly pointed out in the written description and the accompanying drawings. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the layer structure of a multifunctional synaptic transistor with an organic ternary heterocoupled structure provided in an embodiment of this application.

[0037] Figure 2 This is a top view schematic diagram of a multifunctional synaptic transistor with an organic ternary heterocoupled structure provided in an embodiment of this application.

[0038] Figure 3These are microscope images of a bilayer two-dimensional organic molecular crystal film transferred onto a substrate.

[0039] Figure 4 Is Figure 3 Processed images with added markings.

[0040] Figure 5 This is an IT curve of the circularly polarized light-sensitive synaptic behavior of a multifunctional synaptic transistor with an organic ternary heterocoupled structure according to an embodiment of this application.

[0041] Figure 6 This is an IT curve of the broadband response synaptic behavior of a multifunctional synaptic transistor with an organic ternary heterocoupled structure according to an embodiment of this application.

[0042] Figure 7 This is an IT curve diagram of the bidirectional synaptic behavior of a multifunctional synaptic transistor with an organic ternary heterocoupled structure according to an embodiment of this application.

[0043] Reference numerals: 1. Substrate; 2. Gate dielectric layer; 3. N-type organic semiconductor layer; 4. P-type organic semiconductor layer; 5. Chiral COF layer; 6. Source; 7. Drain. Detailed Implementation

[0044] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0045] The following disclosure provides many different embodiments or examples for implementing different structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. Of course, these are merely examples and are not intended to limit the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed.

[0046] It should be understood that, without conflict, any and all embodiments of the present invention can be combined with technical features of any other embodiment or multiple other embodiments to obtain other embodiments. The present invention includes such combinations to obtain other embodiments.

[0047] Unless otherwise specified, all technical and scientific terms used herein have the standard meaning in the field to which the claimed subject matter pertains. Where multiple definitions exist for a term, the definition herein shall prevail.

[0048] Reference Figure 1 This application provides a multifunctional synaptic transistor with an organic ternary heterocoupled structure, including electrodes and a substrate 1, a gate dielectric layer 2, and an organic PN junction stacked sequentially from bottom to top. The organic PN junction includes an N-type organic semiconductor layer 3 and a P-type organic semiconductor layer 4 stacked on the N-type organic semiconductor layer 3. A chiral COF layer 5 with an area smaller than the P-type organic semiconductor layer 4 is disposed on the P-type organic semiconductor layer 4. The electrodes include a source 6 and a drain 7, both of which are in contact with the chiral COF layer 5 and the P-type organic semiconductor layer 4.

[0049] Specifically, the substrate material can be silicon wafers, etc.

[0050] The material of the gate dielectric layer can be, for example, SiO2, HfO2, ZrO2, TiOx, Al2O3, etc.

[0051] The combination of the chiral COF layer and the organic PN junction is called the channel layer. The organic PN junction is composed of two-dimensional organic molecular crystal films with matched energy levels. The N-type organic semiconductor layer, which serves as the two-dimensional organic molecular crystal film, the P-type organic semiconductor layer, which serves as the two-dimensional organic molecular crystal film, and the chiral COF layer are stacked in sequence to form a ternary heterocoupled structure.

[0052] The source and drain materials can be, for example, Au, Ag, or Cu.

[0053] Two-dimensional organic molecular crystal films of P-type organic semiconductor layers can be DTT-8, BTBT-T7, Ph-BTBT-10, etc., with a thickness of 1nm~50nm.

[0054] The two-dimensional organic molecular crystal film of the N-type organic semiconductor layer can be TFT-CN, PDIF-CN2, CMUT, etc., with a thickness of 1nm~50nm.

[0055] The chiral COF layer is either R-TpPa-1-COF or S-TpPa-1-COF, with a thickness of 10 nm to 100 nm, and its energy level is matched with that of the adjacent two-dimensional organic molecular crystal film (P-type organic semiconductor layer).

[0056] Experiments with controlled variables revealed that a single-layer chiral COF can recognize circularly polarized light, but has poor conductivity and photoelectric responsivity; a single-layer organic two-dimensional molecular crystal layer has good conductivity and photoelectric responsivity, but cannot recognize circularly polarized light, and can only respond to a limited wavelength band, nor can it achieve both positive and negative responses simultaneously; after stacking three layers (N-type organic semiconductor layer, P-type organic semiconductor layer, and chiral COF layer), it can not only efficiently recognize circularly polarized light, but also maintain good photoelectric responsivity, and can also achieve bidirectional positive and negative responses; moreover, by combining the three layers with a material system with complementary absorption characteristics, the device can achieve efficient detection function in the full spectrum range of ultraviolet-visible-near infrared.

[0057] This application also provides a method for fabricating a multifunctional synaptic transistor with an organic ternary heterocoupled structure, including the following steps:

[0058] S1: Prepare a gate dielectric layer on the substrate surface.

[0059] S2: An organic PN junction is fabricated on the gate dielectric layer. The organic PN junction includes an N-type organic semiconductor layer and a P-type organic semiconductor layer stacked on the N-type organic semiconductor layer.

[0060] S3: A chiral COF layer is prepared on a P-type organic semiconductor layer, wherein the area of ​​the chiral COF layer is smaller than that of the P-type organic semiconductor layer.

[0061] S4: An electrode is fabricated on a P-type organic semiconductor layer that simultaneously contacts the P-type organic semiconductor layer and the chiral COF layer. The electrode includes a source and a drain.

[0062] The fabrication of the gate dielectric layer and electrodes can follow the existing fabrication methods used in semiconductor devices.

[0063] The preparation steps of the chiral COF layer of R-TpPa-1-COF (or S-TpPa-1-COF) are as follows: A precursor solution is prepared by dissolving 2,4,6-tricarboxymethyl phloroglucinol (TP), p-phenylenediamine (PA), and the chiral inducing agent R-1-phenylethylamine (or S-1-phenylethylamine) in dichloromethane. This solution is further diluted with chlorobenzene, and the mixed solution is dropped onto the surface of deionized water. After maintaining at room temperature for 24 hours, a chiral COF film is formed at the gas-liquid interface, which is then transferred onto a p-type organic semiconductor layer. The area of ​​the chiral COF layer is controlled by the amount of mixed solution dropped onto the deionized water surface.

[0064] The transfer method can be contact retrieval, specifically: align the substrate with the organic PN junction with the chiral COF film on the liquid surface, slowly approach it, and use one side of the P-type organic semiconductor layer to contact the chiral COF film grown on the liquid surface. Once the two are in full contact, slowly lift the substrate away from the liquid surface, and the chiral COF film prepared on deionized water is transferred to the surface of the P-type organic semiconductor layer. After rinsing the substrate with deionized water and air drying, the chiral COF layer can be obtained.

[0065] In the first type of embodiment, the preparation steps of the organic PN junction are as follows:

[0066] S21: Prepare an N-type organic semiconductor solution using a first volatile solvent.

[0067] S22: An N-type organic semiconductor solution is dropped onto a first liquid phase substrate, and an N-type organic semiconductor thin film is obtained after the first volatile solvent evaporates.

[0068] S23: Transfer the N-type organic semiconductor thin film onto the gate dielectric layer to serve as the N-type organic semiconductor layer;

[0069] S24: Prepare a P-type organic semiconductor solution using a second volatile solvent.

[0070] S25: A P-type organic semiconductor solution is dropped onto a second liquid phase substrate, and a P-type organic semiconductor thin film is obtained after the second volatile solvent evaporates.

[0071] S26: Transfer the P-type organic semiconductor thin film onto the N-type organic semiconductor layer to form the P-type organic semiconductor layer.

[0072] An N-type organic semiconductor solution is dropped onto a first liquid phase substrate, and a P-type organic semiconductor solution is dropped onto a second liquid phase substrate; both can be transferred by contact retrieval. Preferably, the first liquid phase substrate is immiscible with the first volatile solvent, the second liquid phase substrate is immiscible with the first volatile solvent, and the second liquid phase substrate is immiscible with the second volatile solvent.

[0073] like Figure 2 As shown, in the three transfers of the N-type organic semiconductor film, the P-type organic semiconductor film, and the chiral COF film, the outline of the N-type organic semiconductor film is smaller than that of the gate dielectric layer, and the outline of the P-type organic semiconductor film is smaller than that of the gate dielectric layer. There are no area requirements for the N-type and P-type organic semiconductor films, as long as there is an overlap. The chiral COF film is smaller than the overlapping part of the N-type and P-type organic semiconductor films.

[0074] In the second type of embodiment, the preparation steps of the organic PN junction are as follows:

[0075] S21': Prepare a mixed solution containing both N-type and P-type organic semiconductors, using a third volatile solvent.

[0076] S22': The mixed solution is dropped onto the third liquid phase substrate. After the third volatile solvent evaporates, a layered and stacked bilayer film is obtained. The bilayer film includes an N-type organic semiconductor film and a P-type organic semiconductor film.

[0077] S23': Transfer the double-layer film onto the gate dielectric layer by oriented the N-type organic semiconductor thin film toward the gate dielectric layer to obtain an organic PN junction.

[0078] The inventors discovered that when P-type and N-type organic semiconductors are dissolved in the same volatile solvent, during the solvent evaporation process, the two-dimensional organic thin films of the P-type and N-type organic semiconductors grow separately due to intermolecular forces, forming a double-layered structure. Thanks to this, the second type of embodiment can reduce one round of preparation, film formation, and transfer steps compared to the first type of embodiment, reducing the hassle of multiple transfer alignments.

[0079] For example, when the P-type organic semiconductor is DDT-8 and the N-type organic semiconductor is TFT-CN, during step S23', observation under a microscope reveals, as follows: Figure 3 As shown. Figure 3 The boundary colors are similar, so manual markings are provided for easier identification. Figure 4 , Figure 4 The “substrate” in the text is a Si wafer with a SiO2 gate dielectric layer. It can be seen that DDT8 and TFT-CN are automatically separated into two layers. The outlines of the two layers do not completely overlap but have overlapping parts.

[0080] The inventors also discovered that when layering in this way, the order in which the two-dimensional organic films of P-type and N-type organic semiconductors are placed on top, and which have a larger or smaller area, is relatively random. Furthermore, when preparing the mixed solution, making the concentration of N-type organic semiconductors higher than that of P-type organic semiconductors increases the probability of forming large-area overlapping organic PN junctions.

[0081] The P-type organic semiconductors selected in this application are DTT-8, BTBT-T7, and Ph-BTBT-10, and the N-type organic semiconductors are TFT-CN, PDIF-CN2, and CMUT. The PN junction of a combination of a P-type organic semiconductor and an N-type organic semiconductor has some color difference, which makes it easy to distinguish what material is on top and what material is on the bottom.

[0082] If a mixed solution of P-type and N-type organic semiconductors is difficult to identify in terms of the correspondence between the layers and the added materials after evaporation, AFM (atomic force microscopy) can be used to measure the thickness to determine the composition of each layer. Generally, the thickness is an integer multiple of the thickness of its own single molecule. For more precise differentiation, TEM (transmission electron microscopy) can also be used for accurate determination.

[0083] In the first and second examples, the first, second, and third liquid phase substrates are independently water, glycerol, or mixtures thereof. Introducing a liquid phase substrate effectively suppresses the coffee ring effect, thereby obtaining a two-dimensional organic molecular crystal with uniform and controllable thickness. The first, second, and third volatile solvents are independently toluene, chlorobenzene, or o-dichlorobenzene, etc., to ensure that the solution evaporates slowly after addition, forming a uniform single-crystal thin film. In the P-type organic semiconductor solution, N-type organic semiconductor solution, and mixed solution, the concentration range of a single solute is 0.01 mg / mL to 2 mg / mL, which can be adjusted according to the thickness and morphology requirements of the target thin film. The amount of solution added to the liquid phase substrate can be precisely controlled according to actual needs. For example, in a weighing bottle with dimensions of 40 mm × 70 mm, the amount added is typically 10 μL to 100 μL. By adjusting the concentration and the amount added, precise control of the thickness of the two-dimensional organic molecular crystal can be achieved, with the thickness ranging from a monolayer to several hundred nanometers.

[0084] In the third type of embodiment, the preparation steps of the organic PN junction are as follows:

[0085] S21”: Prepare a mixed solution containing both N-type and P-type organic semiconductors, using a third volatile solvent.

[0086] S22”: The mixed solution is coated onto the gate dielectric layer, and a PN junction is obtained after the third volatile solvent evaporates.

[0087] Based on the spontaneous layering principle of the mixed solution in the second embodiment, the mixed solution can be directly coated onto the gate dielectric layer. By controlling the uniform and slow movement speed of the scraper, a double-layer two-dimensional molecular crystal heterojunction can be obtained on the substrate surface after coating. The obtained heterojunction has a large area and good crystal quality. The specific coating process is existing technology.

[0088] However, since the order of the two-dimensional organic films of the stacked P-type organic semiconductors and N-type organic semiconductors is random, it is possible to obtain a device with the P-type organic semiconductor on the bottom and the N-type organic semiconductor on the top, which requires redissolving with a volatile solvent.

[0089] All three types of organic PN junction fabrication methods described above can maintain the flatness of each layer interface, resulting in thin films with atomically flat surfaces. Good contact facilitates charge transfer, enabling more integrated functions.

[0090] An example of a multifunctional synaptic transistor with an organic ternary heterocoupled structure of the present invention was subjected to IT (current-time) curve testing using a semiconductor analyzer. In this example device, the substrate is a silicon wafer, the gate dielectric layer is silicon dioxide, the N-type organic semiconductor layer is TFT-CN, the P-type organic semiconductor layer is DTT-8, and the chiral COF material is R-TpPa-1-COF.

[0091] The test lights were left-handed and right-handed circularly polarized light, and the results are as follows. Figure 5 As shown, Figure 5 The results show that the device exhibits circularly polarized light-sensitive synaptic behavior.

[0092] The test light was applied at 365nm, 450nm, 660nm, and 850nm respectively, and the results are as follows. Figure 6 As shown, Figure 6 The results show that the device exhibits a wide-spectrum synaptic response behavior.

[0093] A positive gate voltage was applied to the substrate, and the test light was irradiated at 365nm; a negative gate voltage was then applied to the substrate, and the test light was irradiated at 365nm. The results are as follows. Figure 7 As shown, Figure 7 The results show that the device exhibits a positive response under negative gate voltage conditions and a negative response under positive gate voltage conditions, indicating that the device has bidirectional synaptic behavior.

[0094] This demonstrates that the multifunctional synaptic transistor with the organic ternary heterocoupled structure of the present invention can achieve efficient integration of multiple functions such as circularly polarized light recognition, wide spectral response, and bidirectional synapse.

[0095] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0096] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A multi-functional synapse transistor of an organic ternary heterojunction coupling structure, characterized by, The electrode and the substrate, the gate dielectric layer, the organic PN junction are stacked from bottom to top, the organic PN junction comprises an N-type organic semiconductor layer and a P-type organic semiconductor layer stacked on the N-type organic semiconductor layer, the N-type organic semiconductor layer is a two-dimensional organic molecular crystal film, the P-type organic semiconductor layer is a two-dimensional organic molecular crystal film, a chiral COF layer with an area smaller than the P-type organic semiconductor layer is arranged on the P-type organic semiconductor layer, the electrode comprises a source electrode and a drain electrode, and the source electrode and the drain electrode are in contact with both the chiral COF layer and the P-type organic semiconductor layer. 2.The multifunctional synapse transistor of organic ternary heterojunction structure of claim 1, wherein, The material of the chiral COF layer is R-TpPa-1-COF or S-TpPa-1-COF. 3.The multifunctional synapse transistor of organic ternary heterojunction structure according to claim 2, wherein, The material of the P-type organic semiconductor layer is DTT-8, BTBT-T7 or Ph-BTBT-10.

4. The multifunctional synapse transistor of organic ternary heterojunction structure according to claim 3, wherein, The material of the N-type organic semiconductor layer is TFT-CN, PDIF-CN2 or CMUT. 5.The multifunctional synapse transistor of organic ternary heterojunction structure of claim 1, wherein, The thickness of the chiral COF layer is 10 nm to 100 nm, the thickness of the P-type organic semiconductor layer is 1 nm to 50 nm, and the thickness of the N-type organic semiconductor layer is 1 nm to 50 nm.

6. A method for fabricating a multi-functional synapse transistor of an organic ternary heterojunction coupling structure, characterized in that, The method comprises the following steps: A gate dielectric layer is prepared on the surface of a substrate; An organic PN junction is prepared on the gate dielectric layer, the organic PN junction comprises an N-type organic semiconductor layer and a P-type organic semiconductor layer stacked on the N-type organic semiconductor layer; the N-type organic semiconductor layer is a two-dimensional organic molecular crystal film, and the P-type organic semiconductor layer is a two-dimensional organic molecular crystal film; A chiral COF layer is prepared on the P-type organic semiconductor layer, and the area of the chiral COF layer is smaller than that of the P-type organic semiconductor layer; An electrode is prepared on the P-type organic semiconductor layer, and the electrode is in contact with both the P-type organic semiconductor layer and the chiral COF layer; the electrode comprises a source electrode and a drain electrode.

7. The method of claim 6, wherein the step of forming the multi-functional synapse transistor is performed by a process of: The step of preparing the organic PN junction on the gate dielectric layer comprises: An N-type organic semiconductor solution is prepared, and a first volatile solvent is used as a solvent; The N-type organic semiconductor solution is dropped on a first liquid-phase substrate, and an N-type organic semiconductor thin film is obtained after the first volatile solvent is volatilized; The N-type organic semiconductor thin film is transferred to the gate dielectric layer as the N-type organic semiconductor layer; A P-type organic semiconductor solution is prepared, and a second volatile solvent is used as a solvent; The P-type organic semiconductor solution is dropped on a second liquid-phase substrate, and a P-type organic semiconductor thin film is obtained after the second volatile solvent is volatilized; The P-type organic semiconductor thin film is transferred to the N-type organic semiconductor layer as the P-type organic semiconductor layer.

8. The method of claim 6, wherein the step of forming the multi-functional synapse transistor is performed by a process of: The step of preparing the organic PN junction on the gate dielectric layer comprises: A mixed solution in which an N-type organic semiconductor and a P-type organic semiconductor are dissolved simultaneously is prepared, and a third volatile solvent is used as a solvent; and the mixed solution is processed in one of the following two ways: The first method is to drop the mixed solution on a third liquid phase substrate, and after the third volatile solvent evaporates, a layered and stacked double-layer film is obtained, which includes an N-type organic semiconductor thin film and a P-type organic semiconductor thin film; the double-layer film is transferred to the gate dielectric layer with the N-type organic semiconductor thin film facing the gate dielectric layer, and the organic PN junction is obtained; The second method is to blade coat the mixed solution on the gate dielectric layer, and after the third volatile solvent evaporates, the organic PN junction is obtained.

9. The method of claim 8, wherein the step of forming the multi-functional synapse transistor is performed by a process of: In the mixed solution, the concentration of the N-type organic semiconductor is greater than the concentration of the P-type organic semiconductor.

10. The method of claim 6, wherein the method further comprises: The step of preparing the chiral COF layer on the P-type organic semiconductor layer includes: A precursor solution is prepared by dissolving 2,4,6-triformylphloroglucinol, p-phenylenediamine and a chiral inducer (S-1-phenylethylamine or R-1-phenylethylamine) in dichloromethane, the precursor solution is diluted with chlorobenzene and then dropped on the surface of deionized water, and after standing, a chiral COF film is obtained at the gas-liquid interface, the chiral COF film is transferred to the P-type organic semiconductor layer, and the chiral COF layer is obtained.

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