Synaptic transistor based on MXene ink-jet printing and preparation method thereof

Abstract

The invention discloses a synaptic transistor based on MXene ink-jet printing and a preparation method of the synaptic transistor, relates to the technical field of bionic electronic device printing, and aims to solve the problems of performance reduction, high material cost and high toxicity of an existing device. The preparation method comprises the following steps: selecting a substrate, and cleaning the substrate; patterning the grid electrode, the source electrode and the drain electrode on the substrate by utilizing a photoetching process; depositing a grid electrode, a source electrode and a drain electrode on the substrate; carrying out wet chemical etching on the MAX phase material in combination with mechanical stripping to obtain few layers of MXene; an MXene dispersion liquid with certain sheet diameter size distribution is obtained through a liquid phase cascade centrifugation method; preparing MXene ink; performing hydrophilic treatment on the surface of the substrate, setting printing parameters, and printing an MXene film at the channel position by using the MXene ink; an electrolyte solution is prepared, dielectric layers are dripped on the MXene channel layer, the grid electrode and the exposed substrate, the dielectric layers cover the channel layer and are connected with the grid electrode, and the MXene synapse transistor is constructed.

Description

Technical Field

[0001] The present invention relates to the technical field of printed bionic electronic devices, and in particular to a synaptic transistor based on MXene ink film printing and a preparation method thereof. Background Art

[0002] Artificial intelligence (AI) is rapidly gaining popularity and changing the way we process daily information. The rapid development of these AI technologies is due to innovative algorithms for big data processing (software level) and high-performance semiconductor chips (hardware level). However, computing architectures based on traditional semiconductor devices are not very efficient when performing huge tasks, mainly because the storage and computing processes are separated from each other, which is called the von Neumann bottleneck. Inspired by the structure of the human brain, neuromorphic computing has been developed to achieve parallel computing by simulating the synaptic behavior of biological neural networks. In devices that realize artificial synaptic functions, electrolyte-gated transistors provide a flexible way to simulate synapses. The gate electrode can be regarded as a presynaptic neuron, the channel between the source and drain can be regarded as a postsynaptic neuron, and the conductance of the channel can be used to simulate synaptic weights.

[0003] Among the channel materials used for electrolyte-gated synaptic transistors, two-dimensional MXene materials composed of transition metal carbides, nitrides or carbonitrides show great potential in the field of neuromorphic computing due to their excellent electrical and mechanical properties, hydrophilicity, and adjustable surface end groups. However, the manufacture of most MXene transistors relies on expensive and time-consuming micro-nano processing technologies such as lithography and etching, and the use of organic reagents such as photoresists will also affect the performance of MXene synaptic transistors. Printed electronics technology is gradually showing its advantages due to its economy, strong adaptability, and compatibility with a variety of substrates and different shapes and sizes. Printable MXene synaptic transistors can improve performance, reduce energy consumption, and enhance device characteristics (such as high sensitivity, easy customization of functions, and flexibility), showing great potential in the field of neuromorphic computing.

[0004] Currently, inkjet-printed MXene synaptic crystal devices are still limited by poor electrical properties, thick film layers, and large pattern sizes (millimeter scale), mainly due to the difficulty in printing thin continuous patterns with high precision.

[0005] Most MXene inks use water as a solvent, but the surface tension mismatch between 2D materials and solvents and the imbalance of tiny forces between them usually make it difficult to achieve a stable and uniform printing process. MXene inks that use high-boiling point solvents, such as N,N-dimethylformamide (DMF) and N-methyl-2-pyrrolidone (NMP), are usually supplemented with other surfactants, which can lead to device performance degradation, high material costs and high toxicity, making them unsuitable for large-scale applications. Summary of the invention

[0006] The present invention proposes a method for preparing a synaptic transistor based on MXene inkjet printing, which comprises the following steps: S1: selecting a substrate and cleaning the substrate; S2: patterning the gate, source and drain on the substrate using a photolithography process; S3: depositing a gate, a source and a drain on the substrate; S4: Few-layer MXene is obtained by wet chemical etching combined with mechanical exfoliation of MAX phase materials; S5: MXene dispersion with a certain flake size distribution is obtained by liquid phase cascade centrifugation; S6: preparing a MXene ink using the MXene dispersion; S7: performing hydrophilic treatment on the surface of the substrate, setting the MXene film layer printing parameters, and printing the MXene film at the channel position with the MXene ink; S8: Prepare an electrolyte solution and drop-cast a dielectric layer on the MXene channel layer, the gate and the exposed substrate. The dielectric layer covers the channel layer and is connected to the gate to construct a MXene synaptic transistor.

[0007] The present invention is further configured as follows: the substrate in step S1 is selected to be an insulating rigid material.

[0008] The present invention is further configured as follows: the substrate is made of any one of silicon oxide wafer, glass, ceramic, and sapphire substrate.

[0009] The present invention is further configured as follows: the substrate is cleaned in sequence by acetone, isopropanol, and deionized water, and then blown dry by nitrogen.

[0010] The present invention is further configured as follows: the deposition thickness of each electrode in step S3 is 30-60 nm.

[0011] The present invention is further configured as follows: the MXene material in step S4 is Ti3C2T X 、V2CT X 、Nb2CT X 、Ti3CNT X One of the above; the ratio of ethanol to water in the MXene ink is 1:9 or 2:8 or 3:7.

[0012] The present invention is further configured as follows: the printing parameters set in step S7 include amplitude and speed, wherein the amplitude is 0.5-5V and the speed is 0.01-1mms -1 The thickness of the printed MXene film pattern is 5-15nm.

[0013] The present invention is further configured as follows: in step S8, the dielectric layer is Nafion117 as a proton supply layer, or PEO / LiTFSI as a lithium ion supply layer, wherein the mass ratio of PEO to LiTFSI is 2-5:1

[0014] The present invention also proposes a synaptic transistor based on MXene inkjet printing, which is prepared using the preparation method described in the figure.

[0015] The beneficial effects of the present invention are:

[0016] The inkjet printing process is used to prepare synaptic transistors with MXene as the channel layer, which avoids the impact of traditional micro-nano processing technologies such as photolithography and etching on MXene materials, greatly simplifies the process flow, and greatly reduces the preparation cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic diagram of the structure of the MXene synaptic transistor prepared by the present invention is shown.

[0018] Figure 2 The contact angle between the MXene ink prepared in the present invention and the silicon oxide wafer is shown.

[0019] Figure 3 The figure shows the pattern of the MXene ink prepared in the present invention printed on a silicon oxide wafer.

[0020] Figure 4 An optical microscope image of the MXene synaptic transistor constructed in the present invention is shown.

[0021] Figure 5 A graph showing the transfer characteristics of a MXene synaptic transistor.

[0022] Figure 6 Shown are the response and decay behaviors of the excitatory postsynaptic current of the MXene synaptic transistor.

[0023] Figure 7 Shown is the response and decay behavior of the excitatory synaptic current of the MXene synaptic transistor triggered by a pulse train of increasing amplitude. DETAILED DESCRIPTION

[0024] Those skilled in the art can refer to the content of this article and appropriately improve the process parameters. It is particularly important to point out that all similar replacements and modifications are obvious to those skilled in the art, and they are all considered to be included in the present invention. The methods and applications of the present invention have been described through preferred embodiments, and relevant personnel can modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit and scope of the present invention to implement and apply the technology of the present invention.

[0025] Example 1

[0026] The present invention proposes a method for preparing a synaptic transistor based on MXene ink film printing, comprising the following steps:

[0027] S1: Select a substrate and clean and dry it;

[0028] S2: patterning the gate, source and drain on the substrate using a photolithography process;

[0029] S3: depositing a gate, a source and a drain on the substrate;

[0030] S4: The MAX phase material is subjected to wet chemical etching combined with mechanical exfoliation to obtain a few-layer MXene;

[0031] S5: MXene dispersion with a certain flake size distribution is obtained by liquid phase cascade centrifugation;

[0032] S6: Preparation of MXene ink using MXene dispersion;

[0033] S7: Perform hydrophilic treatment on the surface of the substrate, set the MXene film layer printing parameters, and print the MXene film at the channel position with MXene ink;

[0034] S8: Prepare an electrolyte solution and drop-cast a dielectric layer on the MXene channel layer, the gate and the exposed substrate. The dielectric layer covers the channel layer and connects to the gate to construct a MXene synaptic transistor.

[0035] The substrate in step S1 is made of insulating rigid material, that is, any one of silicon oxide wafer, glass, ceramic, and sapphire substrate.

[0036] The selected substrate needs to be cleaned with acetone, isopropanol and deionized water in turn, and then blown dry with nitrogen after cleaning.

[0037] The deposition method in step S3 can be DC magnetron sputtering or electron beam evaporation, and the material of the deposited electrode is Au or Pt, and the deposition thickness of each electrode is 30-60nm. It should be noted that 5nm Cr needs to be deposited in advance before depositing the electrode.

[0038] The MXene material in step S4 is Ti3C2T X 、V2CT X 、Nb2CT X 、T i3CNT X In step S6, the ratio of ethanol to water in the MXene ink is 1:9, 2:8 or 3:7.

[0039] The hydrophilic treatment in step S7 can be UV ozone treatment or plasma treatment. During the printing process, the needle of the printing device needs to be in direct contact with the substrate surface, and the spray mode is manually activated by applying voltage to the piezoelectric element connected to the micropipette. The set printing parameters include amplitude and speed, where the amplitude is 0.5-5V and the speed is 0.01-1mms -1 The printed MXene film pattern has a thickness of 5-15 nm.

[0040] In step S8, the dielectric layer is Nafion117 as a proton supply layer, or PEO / LiTFSI as a lithium ion supply layer, wherein the mass ratio of PEO to LiTFSI is 2.5-5:1.

[0041] Example 2

[0042] refer to Figure 1 In this embodiment, the preparation method disclosed in Example 1 is used to prepare MXene synaptic transistors based on Ti3C2T X The MXene material synaptic transistor is a side-gate structure, including a substrate, a gate G, a source S, a drain D, a MXene channel layer, and a solid electrolyte dielectric layer. The channel layer is printed by inkjet printing Ti3C2T X The MXene ink is made of MXene, and the dielectric layer is made of drop-cast electrolyte solution. The specific steps are as follows:

[0043] S1: A silicon oxide wafer was selected as the substrate. A 2×2 cm silicon oxide wafer was ultrasonically cleaned in acetone, isopropanol, and deionized water for 5 minutes in sequence to remove pollutants on the surface of the substrate, and then dried with nitrogen.

[0044] S2: Using the photolithography process, the gate, source and drain are patterned on the substrate by spin coating a negative photoresist on the substrate, pre-baking, UV exposure, post-baking, developing and fixing. The channel spacing between the source and the drain is 5μm and the length is 100μm.

[0045] S3: Cr and Au metal electrodes are deposited on the substrate by electron beam evaporation coating method, and the respective deposition thicknesses are 5 nm and 50 nm respectively.

[0046] S4: Preparation of few-layer Ti3C2T X :

[0047] S4-1: Weigh 1.56 g of Li F and add it to 20 ml of 9 M HCL, and stir in a polytetrafluoroethylene beaker for 5 minutes;

[0048] S4-2: Slowly add 1 g of Ti3AlC2 powder to the solution of step S4-1 above, place the polytetrafluoroethylene beaker in an oil bath at 40°C, and continue stirring for 30 hours;

[0049] S4-3: After the reaction, the reaction mixture was washed 5-6 times with deionized water (centrifuged at 5000 rpm for 5 minutes) until the pH reached 6. Finally, the precipitate with obvious swelling at the bottom was multilayer Ti3C2T X ;

[0050] S4-4: Add 30 ml of deionized water to the precipitate in step S4-3, shake manually for 10 minutes, and then pour into a washing bottle. Connect the long port to an inert gas and ultrasonicate for 50 minutes under ventilation and flowing water. At this time, mechanical exfoliation has been completed to obtain Ti3C2T X Dispersion.

[0051] S5: Preparation of few-layer Ti3C2T with different flake size distributions X Dispersion:

[0052] S5-1: After the ultrasound, T i3C2T X The dispersion was centrifuged at 1000 rpm for 30 min, the supernatant was transferred to a new centrifuge tube, and centrifuged at 4000 rpm for another 30 min. The sediment was retained and recorded as 1-4 krpm;

[0053] S5-2: The supernatant was centrifuged at 8000 rpm for 30 min, and the sediment was retained and recorded as 4-8 krpm;

[0054] S5-3: Finally, the supernatant was centrifuged at 12000 rpm for 30 min, and the precipitate was retained and recorded as 8-12 krpm;

[0055] S5-4: After the above cascade centrifugation process, three types of Ti3C2T can be obtained: 1-4k, 4-8k and 8-12krpm X 10 mL of deionized water was added to each of the precipitates, and the precipitates were redispersed in water by hand shaking for 10 min. Thus, three sizes of Ti3C2T X Dispersion.

[0056] S6: Preparation of Ti3C2T X Ink, T i3C2T X The solute concentration is 1 mg / ml, the solvent is anhydrous ethanol: deionized water = 1:9, and the solution is evenly dispersed by hand shaking and set aside for later use.

[0057] S7: Inkjet printing

[0058] S7-1: Place the substrate into a UV ozone machine and irradiate with UV light for 20 minutes;

[0059] S7-2: The needle diameter used is 20μm, the designed printing pattern program is called, and the printing parameters are adjusted, that is, the nozzle amplitude is 1.5V, the nozzle frequency is 450kHz, and the speed is 0.1mms -1 The printed MXene film area is 20μm×100μm. The printed MXene film is heat treated at 90°C in a vacuum drying oven for 30 minutes to enhance the adhesion between the substrate and MXene and promote the volatilization of the solvent.

[0060] S8: Building T i3C2T X Synaptic Transistor:

[0061] S8-1: Weigh 250 g of polyethylene oxide and 100 g of lithium bis(fluorosulfonyl)imide salt, add them to 10 ml of anhydrous acetonitrile, and stir at 60° C. overnight until the solution becomes transparent;

[0062] S8-2: Use a pipette to drop 2 μL of electrolyte solution onto the channel layer, gate and exposed substrate. The dielectric layer covers the channel layer and connects to the gate.

[0063] S8-3: Place the device in a vacuum drying oven at 90°C for 20 minutes to remove unvolatile acetonitrile.

[0064] refer to Figure 2 It can be seen that the prepared Ti3C2T X The contact angle of the ink on the silicon oxide wafer is 45°, referring to Figure 3 The pattern is continuously printed by the ink under the parameters of step S7. It can be seen that the pattern is stable and uniform, without coffee ring closure and Rayleigh instability effect. Figure 4 The prepared Ti3C2T X Light microscopy image of a synaptic transistor.

[0065] refer to Figure 5 In order to test the transfer characteristics of the synaptic transistor prepared above using a semiconductor parameter analyzer, a small DC voltage V is applied between the source and the drain. DS =100mV, so that the gate voltage V G Scan once from 3V to -3V and then to 3V, set different scanning speeds, and record the channel current I D As you can see, V G = 0V, there is an obvious hysteresis phenomenon, which shows that the channel conductance undergoes non-volatile changes under electrochemical doping, which is crucial for the simulation of synaptic performance.

[0066] Example 3

[0067] This example uses the preparation method disclosed in Example 1 to prepare MXene synaptic transistors based on V2CT X The MXene material synaptic transistor is a side-gate structure, including a substrate, a gate G, a source S, a drain D, a MXene channel layer, and a solid electrolyte dielectric layer. The channel layer is printed by inkjet V2CT. X The MXene ink is made of MXene, and the dielectric layer is made of drop-cast electrolyte solution. The specific steps are as follows:

[0068] S1: A glass sheet was selected as a substrate. A 2×2 cm glass sheet was ultrasonically cleaned in acetone, isopropanol, and deionized water for 5 minutes in sequence to remove pollutants on the surface of the substrate, and then dried with nitrogen.

[0069] S2: Using the photolithography process, the gate, source and drain are patterned on the substrate by spin coating a negative photoresist on the substrate, pre-baking, UV exposure, post-baking, developing and fixing. The channel spacing between the source and the drain is 5μm and the length is 100μm.

[0070] S3: Cr and Au metal electrodes are deposited on the substrate by DC magnetron sputtering, and the thickness of each deposition is 5 nm and 60 nm, respectively.

[0071] S4: Preparation of few-layer V2CT X :

[0072] S4-1: Slowly add 2g of V2A l C powder into 40ml of HF with a mass fraction of 49%, place the polytetrafluoroethylene beaker in an oil bath at 40℃, and continue stirring for 72 hours;

[0073] S4-2: After the reaction, the reaction mixture was washed 5-6 times with deionized water (centrifuged at 8000 rpm for 5 minutes) until the pH reached 6. The final precipitate was multilayer V2CT. X ;

[0074] S4-3: Add 1 g of the precipitate obtained in step S4-2 to 20 ml of a 5 wt% tetra-n-butylammonium hydroxide solution, and stir at 25° C. for 6 hours;

[0075] S4-4: After stirring, transfer the solution to a certain amount of deionized water, centrifuge at 5000 rpm for 5 minutes, pour out the upper liquid, disperse the precipitate in deionized water and shake by hand for 5 minutes, repeat the steps of centrifugation and shaking by hand until the color of the upper liquid becomes darker.

[0076] S5: Preparation of few-layer V2CT with different flake size distributions X Dispersion:

[0077] S5-1: V2CT after ultrasound X The dispersion was centrifuged at 1000 rpm for 30 min, the supernatant was transferred to a new centrifuge tube, and centrifuged at 4000 rpm for another 30 min. The sediment was retained and recorded as 1-4 krpm;

[0078] S5-2: The supernatant was centrifuged at 8000 rpm for 30 min, and the sediment was retained and recorded as 4-8 krpm;

[0079] S5-3: Finally, the supernatant was centrifuged at 12000 rpm for 30 min, and the precipitate was retained and recorded as 8-12 krpm;

[0080] S5-4: After the above cascade centrifugation process, three types of V2CT can be obtained: 1-4k, 4-8k and 8-12krpm X After precipitation, 10 mL of deionized water was added to each of them and the precipitate was redispersed in water by hand shaking for 10 min. Thus, three size distributions of V2CT were obtained. X Dispersion.

[0081] S6: Preparation of V2CT X Ink, V2CT X The solute concentration is 1 mg / ml, the solvent is anhydrous ethanol: deionized water = 2:8, and the solution is evenly dispersed by hand shaking and set aside for later use.

[0082] S7: Inkjet printing

[0083] S7-1: placing the substrate into a plasma etcher and treating it with oxygen plasma for 3 minutes;

[0084] S7-2: The needle diameter used is 20μm, the designed printing pattern program is called, and the printing parameters are adjusted, that is, the nozzle amplitude is 2V, the nozzle frequency is 450kHz, and the speed is 0.3mms -1 The printed MXene film area is 20μm×100μm. The printed MXene film is heat treated at 90°C in a vacuum drying oven for 30 minutes to enhance the adhesion between the substrate and MXene and promote the volatilization of the solvent.

[0085] S8: Building V2CT X Synaptic Transistor:

[0086] S8-1: Use a pipette to take 2 μL of Nafion 117 solution and drop-cast it on the channel layer, gate and exposed substrate. The dielectric layer covers the channel layer and connects the gate.

[0087] S8-2: Place the device in a vacuum drying oven at 90°C for 20 minutes to remove the unvolatile solvent.

[0088] Changed the channel material to V2CT X The electrolyte solution was replaced with Nafion117 to provide protons for the channel layer. The V2CT prepared above was analyzed using a semiconductor parameter analyzer. X MXene synaptic transistor undergoes pulse testing. Figure 6 , the pulse voltage applied to the gate is 3V, the pulse width is 100ms, the voltage between the source and the drain is set to 100mV, the excitatory postsynaptic current reaches the maximum value at the moment the pulse ends, and then gradually falls back, but does not fall back to the initial value, showing long-term memory (10 2 s) Characteristics. Reference Figure 7 , a series of linearly increasing pulses (0.5-3V) were applied to the gate, and the current response increased with the increase of pulse amplitude. This electrical property is similar to the signal behavior in biological excitatory synapses.

[0089] Example 4

[0090] refer to Figure 1 In this embodiment, the preparation method disclosed in Example 1 is used to prepare MXene synaptic transistors based on Ti3CNT X The MXene material synaptic transistor is a side-gate structure, including a substrate, a gate G, a source S, a drain D, a MXene channel layer, and a solid electrolyte dielectric layer. The channel layer is printed by inkjet printing Ti3CNT X The MXene ink is made of MXene, and the dielectric layer is made of drop-cast electrolyte solution. The specific steps are as follows:

[0091] S1: A sapphire substrate was selected as the substrate. The 2×2 cm sapphire substrate was ultrasonically cleaned in acetone, isopropanol, and deionized water for 5 minutes in sequence to remove pollutants on the surface of the substrate, and then dried with nitrogen.

[0092] S2: Using the photolithography process, the gate, source and drain are patterned on the substrate by spin coating a negative photoresist on the substrate, pre-baking, UV exposure, post-baking, developing and fixing. The channel spacing between the source and the drain is 5μm and the length is 100μm.

[0093] S3: Cr and Au metal electrodes are deposited on the substrate by electron beam evaporation, and the thickness of each deposition is 5 nm and 60 nm respectively.

[0094] S4: Preparation of few-layer Ti3CNT X :

[0095] S4-1: Weigh 1.6 g of Li F and add it to 20 ml of 9 M HCL, and stir in a polytetrafluoroethylene beaker for 15 minutes;

[0096] S4-2: Slowly add 1 g of Ti3AlCN powder to the solution of step S4-1 above, place the polytetrafluoroethylene beaker in an oil bath at 35°C, and continue stirring for 18 hours;

[0097] S4-3: After the reaction is completed, the reaction mixture is washed 7-8 times with deionized water (centrifuged at 3500 rpm for 1 minute) until the pH reaches 6, and then vacuum filtered;

[0098] S4-4: Add the precipitate after vacuum filtration back into the centrifuge tube and continue centrifugation until a sticky precipitate appears and the supernatant turns black, then stop centrifugation and discard the supernatant;

[0099] S4-5: Add 30 ml of deionized water to the precipitate in step S4-4, shake manually for 20 minutes, and then pour it into a washing bottle. Connect the long port to an inert gas and ultrasonicate for 50 minutes under ventilation and flowing water. At this time, mechanical exfoliation has been completed to obtain Ti3CNT X Dispersion.

[0100] S5: Preparation of few-layer Ti3CNT with different sheet size distributions X Dispersion:

[0101] S5-1: After the ultrasonic treatment, Ti3CNT X The dispersion was centrifuged at 1000 rpm for 30 min, the supernatant was transferred to a new centrifuge tube, and centrifuged at 4000 rpm for another 30 min. The sediment was retained and recorded as 1-4 krpm;

[0102] S5-2: The supernatant was centrifuged at 8000 rpm for 30 min, and the sediment was retained and recorded as 4-8 krpm;

[0103] S5-3: Finally, the supernatant was centrifuged at 12000 rpm for 30 min, and the precipitate was retained and recorded as 8-12 krpm;

[0104] S5-4: After the above cascade centrifugation process, three types of Ti3CNT can be obtained: 1-4k, 4-8k and 8-12krpm X After precipitation, 10 mL of deionized water was added to each of them and the precipitate was redispersed in water by hand shaking for 10 min. Thus, three sizes of Ti3CNT were obtained. X Dispersion.

[0105] S6: Preparation of Ti3CNT X Ink, Ti3CNT X The solute concentration of the solution is 1 mg / ml, the solvent is anhydrous ethanol: deionized water = 3:7, the solution is dispersed evenly by hand shaking and set aside for later use.

[0106] S7: Inkjet printing

[0107] S7-1: Place the substrate into a UV ozone machine and irradiate with UV light for 20 minutes;

[0108] S7-2: The needle diameter used is 20μm, the designed printing pattern program is called, and the printing parameters are adjusted, that is, the nozzle amplitude is 0.5V, the nozzle frequency is 450kHz, and the speed is 0.5mms -1 The printed MXene film area is 20μm×100μm. The printed MXene film is heat treated at 90°C in a vacuum drying oven for 30 minutes to enhance the adhesion between the substrate and MXene and promote the volatilization of the solvent.

[0109] S8: Construction of Ti3CNT X Synaptic Transistor:

[0110] S8-1: Weigh 250 g of polyethylene oxide and 100 g of lithium bis(fluorosulfonyl)imide salt, add them to 10 ml of anhydrous acetonitrile, and stir at 60° C. overnight until the solution becomes transparent;

[0111] S8-2: Use a pipette to drop 2 μL of electrolyte solution onto the channel layer, gate and exposed substrate. The dielectric layer covers the channel layer and connects to the gate.

[0112] S8-3: Place the device in a vacuum drying oven at 90°C for 20 minutes to remove unvolatile acetonitrile.

[0113] Example 5

[0114] This example uses the preparation method disclosed in Example 1 to prepare MXene synaptic transistors based on N2CT X The MXene material synaptic transistor is a side-gate structure, including a substrate, a gate G, a source S, a drain D, a MXene channel layer, and a solid electrolyte dielectric layer. The channel layer is printed by inkjet printing N2CT X The MXene ink is made of MXene, and the dielectric layer is made of drop-cast electrolyte solution. The specific steps are as follows:

[0115] S1: A silicon oxide wafer was selected as the substrate. A 2×2 cm silicon oxide wafer was ultrasonically cleaned in acetone, isopropanol, and deionized water for 5 minutes in sequence to remove pollutants on the surface of the substrate, and then dried with nitrogen.

[0116] S2: Using the photolithography process, the gate, source and drain are patterned on the substrate by spin coating a negative photoresist on the substrate, pre-baking, UV exposure, post-baking, developing and fixing. The channel spacing between the source and the drain is 5μm and the length is 100μm.

[0117] S3: Cr and Pt metal electrodes are deposited on the substrate by DC magnetron sputtering, and the thickness of each deposition is 5 nm and 50 nm respectively.

[0118] S4: Preparation of few-layer N2CT X :

[0119] S4-1Nb2Al C Slowly add 1g Nb2Al C powder into 20ml HF with a mass fraction of 49%, put the polytetrafluoroethylene beaker into an oil bath at 60℃, and continue stirring for 90 hours;

[0120] S4-2: After the reaction, the reaction mixture was washed 5-6 times with deionized water (centrifuged at 5000 rpm for 5 minutes) until the pH reached 6. The final precipitate was multilayer N2CT. X ;

[0121] S4-3: 0.5 g of the precipitate obtained in step S4-2 was added to 10 ml of a 5 wt% tetra-n-butylammonium hydroxide solution and stirred at 25° C. for 8 hours;

[0122] S4-4: After stirring, transfer the solution to a certain amount of deionized water, centrifuge at 5000 rpm for 5 minutes, pour out the upper liquid, disperse the precipitate in deionized water and shake by hand for 5 minutes, repeat the steps of centrifugation and hand shaking until the color of the upper liquid becomes darker.

[0123] S5: Preparation of few-layer N2CT with different flake size distributions X Dispersion:

[0124] S5-1: N2CT after ultrasound X The dispersion was centrifuged at 1000 rpm for 30 min, the supernatant was transferred to a new centrifuge tube, and centrifuged at 4000 rpm for another 30 min. The sediment was retained and recorded as 1-4 krpm;

[0125] S5-2: The supernatant was centrifuged at 8000 rpm for 30 min, and the sediment was retained and recorded as 4-8 krpm;

[0126] S5-3: Finally, the supernatant was centrifuged at 12000 rpm for 30 min, and the precipitate was retained and recorded as 8-12 krpm;

[0127] S5-4: After the above cascade centrifugation process, three types of N2CT can be obtained: 1-4k, 4-8k and 8-12krpm X 10 mL of deionized water was added to each of the precipitates, and the precipitates were redispersed in water by hand shaking for 10 min. Thus, three sizes of N2CT were obtained. X Dispersion.

[0128] S6: Preparation of N2CT X Ink, N2CT X The solute concentration of the solution is 1 mg / ml, the solvent is anhydrous ethanol: deionized water = 3:7, the solution is dispersed evenly by hand shaking and set aside for later use.

[0129] S7: Inkjet printing

[0130] S7-1: placing the substrate into a plasma machine and subjecting it to oxygen plasma treatment for 3 minutes;

[0131] S7-2: The needle diameter used is 20μm, the designed printing pattern program is called, and the printing parameters are adjusted, that is, the nozzle amplitude is 3V, the nozzle frequency is 450kHz, and the speed is 0.75mms -1 The printed MXene film area is 20μm×100μm. The printed MXene film is heat treated at 90°C in a vacuum drying oven for 30 minutes to enhance the adhesion between the substrate and MXene and promote the volatilization of the solvent.

[0132] S8: Building N2CT X Synaptic Transistor:

[0133] S8-1: Use a pipette to take 2 μL of Nafion 117 solution and drop-cast it on the channel layer, gate and exposed substrate. The dielectric layer covers the channel layer and connects to the gate.

[0134] S8-3: Place the device in a vacuum drying oven at 90°C for 20 minutes to remove the unvolatile solution.

[0135] Example 6

[0136] This embodiment discloses a synaptic transistor based on MXene inkjet printing, which is prepared by the preparation method described in any one of Examples 1-5.

[0137] In summary, the present invention adopts inkjet printing technology to prepare synaptic transistors with MXene as the channel layer, avoiding the influence of traditional micro-nano processing technologies such as photolithography and etching on MXene materials, and greatly simplifying the process flow, greatly reducing the preparation cost. The MXene material with a narrow flake size distribution developed by the present invention is configured into an ink without additional surfactant, and a uniform and continuous ultra-thin pattern (5-15nm) is printed on various substrates. The surface of the MXene synaptic transistor printed by inkjet of the present invention has an enhanced non-volatile retention time (10 2 s) and successfully simulated the biological behavior of the human brain.

[0138] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be within the scope of protection of the present invention.

Claims

1. A method for preparing a synaptic transistor based on MXene inkjet printing, characterized in that: The following steps are included: S1: selecting a substrate and cleaning the substrate; S2: patterning the gate, source and drain on the substrate using a photolithography process; S3: depositing a gate, a source and a drain on the substrate; S4: Few-layer MXene is obtained by wet chemical etching combined with mechanical exfoliation of MAX phase materials; S5: MXene dispersion with a certain flake size distribution is obtained by liquid phase cascade centrifugation; S6: preparing a MXene ink using the MXene dispersion; S7: performing hydrophilic treatment on the surface of the substrate, setting the MXene film layer printing parameters, and printing the MXene film at the channel position with the MXene ink; S8: Prepare an electrolyte solution and drop-cast a dielectric layer on the MXene channel layer, the gate and the exposed substrate. The dielectric layer covers the channel layer and is connected to the gate to construct a MXene synaptic transistor.

2. The method for preparing a synaptic transistor based on MXene inkjet printing according to claim 1, characterized in that: The substrate in step S1 is selected to be an insulating rigid material.

3. The method for preparing a synaptic transistor based on MXene inkjet printing according to claim 2, characterized in that: The substrate is made of any one of silicon oxide wafer, glass, ceramic and sapphire substrate.

4. The method for preparing a synaptic transistor based on MXene inkjet printing according to claim 1 or 3, characterized in that: The substrate was cleaned in sequence with acetone, isopropanol and deionized water, and then dried with nitrogen.

5. The method for preparing a synaptic transistor based on MXene inkjet printing according to claim 1, characterized in that: The deposition thickness of each electrode in step S3 is 30-60 nm.

6. The method for preparing a synaptic transistor based on MXene inkjet printing according to claim 1, characterized in that: The MXene material in step S4 is Ti3C2T X 、V2CT X 、Nb2CT X 、Ti3CNT X One of the above; the ratio of ethanol to water in the MXene ink is 1:9 or 2:8 or 3:

7.

7. The method for preparing a synaptic transistor based on MXene inkjet printing according to claim 1, characterized in that: The printing parameters set in step S7 include amplitude and speed, where the amplitude is 0.5-5V and the speed is 0.01-1mms -1 The thickness of the printed MXene film pattern is 5-15nm.

8. The method for preparing a synaptic transistor based on MXene inkjet printing according to claim 1, characterized in that: In step S8, the dielectric layer is Nafion 117 as a proton supply layer, or PEO / LiTFSI as a lithium ion supply layer, wherein the mass ratio of PEO to LiTFSI is 2.5-5:

1.

9. A synaptic transistor based on MXene inkjet printing, characterized in that: The method is prepared according to any one of claims 1 to 8.

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