Monomolecular memristor based on viologen derivative and preparation method thereof

Abstract

The present application relates to the field of microelectronics, and particularly relates to a single-molecule memristor based on a viologen derivative and a preparation method thereof.The single-molecule memristor based on the viologen derivative comprises an electrode pair and an organic functional molecule, the organic functional molecule is selected from a viologen derivative, and is assembled between the electrode pair through an amide condensation reaction.The organic functional molecule provided by the present application is modified in function on the basis of a viologen molecular structure, effectively reduces the energy barrier of a reversible redox reaction of a viologen unit, and thus significantly improves the performance of the single-molecule memristor;at the same time, the switching ratio of the device is also improved by an order of magnitude.The preparation method provided by the present application can ensure the stability and repeatability of the single-molecule device, and effectively improves the conductive stability and durability of a molecular junction of the organic functional molecule.The method is simple to operate and the reaction conditions are easy to control, and is conducive to realizing the large-scale production of molecular devices.

Description

Technical Field

[0001] This invention relates to the field of microelectronics technology, and in particular to a single-molecule memristor based on viologen derivatives and its preparation method. Background Technology

[0002] As semiconductor process nodes continue to approach their physical limits, the development of electronic devices in the post-Moore's Law era urgently requires technological breakthroughs with new principles and structures. Against this backdrop, single-molecule devices, as the ultimate scale for miniaturizing electronic devices, have become an important research direction for overcoming the size limitations of traditional silicon-based devices.

[0003] Memristors, as the fourth fundamental circuit element after resistors, capacitors, and inductors, possess significant potential in constructing novel high-density, low-power memories and neuromorphic computing chips due to their non-volatile resistive-state switching characteristics. Traditional memristors are generally based on specific materials such as metal oxides, and their switching mechanism originates from conductive filaments formed by ion migration. However, as device dimensions approach the nanoscale, these devices face severe challenges such as drastic performance fluctuations and miniaturization limitations.

[0004] Molecular memristor devices achieve resistive state switching through redox reactions or configurational transitions of individual molecules, offering advantages such as defined structure and predictable switching behavior, providing new possibilities for continuing the miniaturization of devices. However, various challenges remain, such as insufficient molecular stability, uncontrollable electrode-molecule interface contact, and poor device repeatability, which hinder their practical application. Especially in constructing high-density integrated arrays, achieving precise positioning and stable connection of single-molecule junctions has become a key technical challenge.

[0005] Therefore, there is an urgent need to develop a single-molecule memristor that can precisely control the coupling between molecules and electrodes and has both high repeatability and stability. Summary of the Invention

[0006] The present invention aims to at least solve one of the technical problems existing in the related art. Therefore, the first objective of the present invention is to provide a single-molecule memristor based on viologen derivatives; the second objective of the present invention is to provide a method for preparing a single-molecule memristor based on viologen derivatives.

[0007] To achieve the first objective, the technical solution adopted by this invention is as follows:

[0008] Single-molecule memristors based on viologen derivatives include:

[0009] A first electrode and a second electrode, wherein the first electrode and the second electrode form an electrode pair;

[0010] An organic functional molecule, selected from viologen derivatives, has the following structural formula:

[0011] ;

[0012] Where R is selected from , and any one of them;

[0013] The organic functional molecules are assembled between the electrode pairs via an amide condensation reaction.

[0014] Viologen molecules possess significant dual redox properties, undergoing reversible redox reactions under external electric field excitation, accompanied by significant changes in molecular electronic structure. This results in a change in conductivity by several orders of magnitude, making it one of the ideal materials for constructing single-molecule memristors, the theoretically smallest memristor units. This invention functionalizes the viologen molecular structure, effectively lowering the energy barrier for reversible redox reactions in viologen units, thereby significantly improving the performance of single-molecule memristors. Compared to single-molecule devices based on the viologen core, the viologen derivative-based single-molecule device provided by this invention exhibits a lower operating voltage after voltage application, meaning a significant reduction in power consumption. Simultaneously, the on / off ratio of the device is improved by an order of magnitude, achieving higher energy efficiency and performance in the fabrication of single-molecule memristors. The viologen derivative-based single-molecule memristor provided by this invention not only offers a novel candidate for high-density information storage but also lays the foundation for simulating neural synaptic behavior and developing next-generation neuromorphic computing hardware.

[0015] Furthermore, the electrode pair is made of a single-layer graphene film.

[0016] Furthermore, the gap between the electrode pairs is at the nanometer level.

[0017] Furthermore, the electrode pair is a triangular electrode array point electrode.

[0018] Furthermore, individual organic functional molecules are connected between the electrode pairs.

[0019] To achieve the second objective, the technical solution adopted by this invention is as follows:

[0020] A method for preparing a single-molecule memristor based on viologen derivatives, used to prepare any of the above-mentioned single-molecule memristors based on viologen derivatives, includes the following steps of assembling organic functional molecules with electrode pairs:

[0021] Under inert gas conditions, an organic solution containing the organic functional molecule and the condensing agent is added to a container holding the electrode pair, and then pyridine is added. The reaction is carried out for at least 24 hours, so that the organic functional molecule is connected to the electrode pair through an amide bond, thereby obtaining a single-molecule memristor based on viologen derivatives.

[0022] Furthermore, the condensing agent is selected from 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride or N,N'-dicyclohexylcarbodiimide.

[0023] Furthermore, the organic solution is selected from acetonitrile.

[0024] Further, the preparation of the electrode pair includes the following steps:

[0025] S100. Graphene films are prepared on copper substrates using chemical vapor deposition (CVD).

[0026] S200: The graphene film is transferred onto a silicon substrate to obtain a silicon substrate loaded with a single layer of graphene.

[0027] S300. A graphene electrode array with nano-gap is prepared on a silicon substrate carrying a single layer of graphene by photolithography, sputtering and etching processes to obtain the electrode pair.

[0028] Furthermore, in step S300, the etching process employs plasma etching technology.

[0029] The above-described one or more technical solutions in the embodiments of the present invention have at least one of the following technical effects:

[0030] This invention provides a single-molecule memristor based on viologen derivatives. By introducing viologen derivatives as organic functional molecules, these derivatives functionalize the viologen molecule, effectively lowering the energy barrier for reversible redox reactions in viologen units, thus significantly improving the performance of the single-molecule memristor. Furthermore, the single-molecule device provided by this invention exhibits a lower operating voltage after voltage application, meaning a significant reduction in power consumption. Simultaneously, the on / off ratio of the device is improved by an order of magnitude, achieving higher energy efficiency and performance in the fabrication of single-molecule memristors. This viologen-derived single-molecule memristor not only provides a novel candidate for high-density information storage but also lays the foundation for simulating neural synaptic behavior and developing next-generation neuromorphic computing hardware.

[0031] The present invention provides a method for preparing single-molecule memristors based on viologen derivatives, which enables the organic functional molecules to be covalently linked to the electrode pairs via amide bonds. This ensures the stability and reproducibility of the single-molecule device while effectively improving the conductivity stability and durability of the organic functional molecule molecular junction. The method is simple to operate and the reaction conditions are easy to control. Combined with the efficient coupling reaction under an inert atmosphere, it is beneficial for the large-scale production of molecular devices.

[0032] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the structure of a single-molecule memristor based on viologen derivatives provided in an embodiment of the present invention.

[0034] Figure 2 This is the current-voltage characteristic curve of a single-molecule memristor based on viologen derivatives provided in Embodiment 4 of the present invention.

[0035] Figure 3 This is the current-voltage characteristic curve of a single-molecule memristor based on viologen nucleus molecules provided in Embodiment 4 of the present invention.

[0036] Figure label:

[0037] 11. First electrode; 12. Second electrode; 2. Organic functional molecule. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention. The following embodiments are used to illustrate this invention, but cannot be used to limit the scope of this invention.

[0039] like Figure 1 As shown, a single-molecule memristor based on viologen derivatives includes:

[0040] A first electrode 11 and a second electrode 12, wherein the first electrode 11 and the second electrode 12 form an electrode pair;

[0041] Organic functional molecule 2, wherein the organic functional molecule is selected from viologen derivatives, and its structural formula is shown below:

[0042] ;

[0043] Where R is selected from , and any one of them;

[0044] The organic functional molecules are assembled between the electrode pairs via an amide condensation reaction.

[0045] According to a specific embodiment of the present invention, the electrode pair is made of a single-layer graphene film.

[0046] According to a specific embodiment of the present invention, the gap between the electrode pairs is at the nanometer level.

[0047] According to a specific embodiment of the present invention, the electrode pair is a triangular electrode array point electrode.

[0048] According to a specific embodiment of the present invention, a single organic functional molecule is connected between the electrode pairs.

[0049] In the following embodiments, unless otherwise specified, the experimental methods used are conventional methods, and the materials and reagents used are commercially available, unless otherwise specified, and are carried out in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions.

[0050] Example 1: Preparation of Organic Functional Molecules .

[0051] I. Preparation of Compound 1 The process is as follows:

[0052] Will (0.01 mol) was dissolved in anhydrous dimethylformamide (DMF) (20 mL), and then sodium hydride (0.015 mol) was added to the solution under nitrogen protection. (0.015 mol), under room temperature conditions, after stirring for 5 h, water (10 mL) was added, and then extracted with chloroform (20 mL × 3). The organic phases were combined and dried with sodium sulfate, and then purified by reverse high performance liquid chromatography to obtain compound 1.

[0053] In the reverse high performance liquid chromatography method, the eluent is a mixed solvent of ethyl acetate and n-hexane (the volume ratio of ethyl acetate to n-hexane is 1:3), the flow rate is 3 mL / min, and the detection wavelength is 240 nm.

[0054] II. Preparation of Compound 2 The process is as follows:

[0055] Under light-protected conditions, 0.002 mmol of bis(hexafluoroacetylacetone)palladium and 0.004 mmol of tri-tert-butylphosphine tetrafluoroborate were added to the reaction vessel; subsequently, under argon protection, 2.5 mL of dry N,N-dimethylpropenylurea was added. After stirring at room temperature for 10 min, compound 1 (0.05 mol) was added sequentially. (0.25 mol) and N,N-diisopropylethylamine (0.075 mmol); the reactor was sealed and placed in an oil bath at 120°C, and the reaction was stirred at 800 rpm for 36 h, and monitored by gas chromatography until the aryl halide was completely consumed; finally, the compound 2 was obtained by chromatographic purification (the eluent was a mixed solvent of ethyl acetate and n-hexane, with a volume ratio of 1:10).

[0056] III. Preparation of Compound 3 The process is as follows:

[0057] Compound 2 (0.1 mmol) was dissolved in anhydrous tetrahydrofuran (10 mL) under a hydrogen atmosphere, and then 10 wt% palladium on carbon catalyst (0.002 mmol) was added. The mixture was stirred for 16 h. After the reaction was completed, the mixture was filtered through a diatomaceous earth mat and the filter cake was washed with ethyl acetate (100 mL). The organic phases were combined and washed successively with 10 wt% sodium carbonate aqueous solution (15 mL) and saturated NaCl aqueous solution (20 mL × 2). The organic layer was dried over anhydrous magnesium sulfate and the solvent was removed by vacuum concentration. The mixture was then purified by column chromatography (using a mixture of petroleum ether and ethyl acetate as eluent in a volume ratio of 3:2) to obtain compound 3.

[0058] IV. Preparation of Compound 4 The process is as follows:

[0059] Under nitrogen protection, an anhydrous tetrahydrofuran solution (20 mL) containing compound 3 (0.01 mol) and n-butyllithium (0.012 mol) was added to a dry reaction vessel. The temperature was lowered to -78°C and maintained for 15 min. Subsequently, trimethyl borate (0.015 mol) was slowly added through a constant-pressure dropping funnel. After maintaining the reaction at -78°C for 2 h, the temperature was raised to room temperature and the reaction continued overnight. Then, the temperature was lowered to 0°C, and tripotassium phosphate (0.013 mol) was added. A solution of 0.0005 mol of tetra(triphenylphosphine)palladium in 1,2-dimethoxyethane (10 mL) and deionized water (2 mL) was prepared. The mixture was brought to room temperature and stirred for 24 h. Then, it was heated to 60°C until the starting material was completely converted (monitored by thin-layer chromatography). After cooling, the reaction solution was filtered through a diatomaceous earth filter. The filter cake was washed with ethyl acetate until the eluent was colorless. The combined organic phases were washed with saturated brine, dried over anhydrous sodium sulfate, and then concentrated under reduced pressure to obtain the crude product of compound 4. Finally, the crude product was purified by column chromatography (using a mixture of petroleum ether and ethyl acetate as the eluent, with a volume ratio of 3:1) to obtain compound 4.

[0060] V. Preparation of Organic Functional Molecules The process is as follows:

[0061] Under a nitrogen atmosphere, compound 4 (1 mmol) and sodium tert-butoxide (1.2 mmol) were dissolved in xylene (20 mL). After stirring at room temperature for 20 min, bis(dibenzylacetone)palladium (0.0005 mmol) was added. (1.2 mmol), then heated to 130°C, reacted for 2.50 h, quenched with ice water, extracted with ethyl acetate, washed with saturated brine, dried over anhydrous sodium sulfate, concentrated by rotary evaporation, and then purified by column chromatography (eluent was a mixture of petroleum ether and ethyl acetate, volume ratio 3:1) to obtain the target organic functional molecule. 1 The H NMR characterization data are as follows:

[0062] 1 ¹H NMR (300 MHz, dimethyl sulfoxide-d6): δ 9.42 (s, 2H), 8.41–8.01 (m, 8H), 8.33 (d, J = 7.5 Hz, 2H), 7.49–7.47 (m, 4H), 6.86 (d, J = 6.2 Hz, 2H), 6.50–6.40 (m, 4H), 5.01 (s, 4H), 2.90 (d, J = 7.0 Hz, 4H), 2.68 (t, J = 7.1 Hz, 4H), 2.29 (t, J = 7.1 Hz, 4H), 1.50 (s, 2H, NH₂).

[0063] Example 2 Preparation of organic functional molecules .

[0064] In addition to the preparation process of the target organic functional molecule in Example 1 (1.2 mmol) replaced with (1.5 mmol), the rest of the process is the same as in Example 1.

[0065] The target organic functional molecule obtained in this embodiment 1 The H NMR characterization data are as follows:

[0066] 1 ¹H NMR (300 MHz, dimethyl sulfoxide-d6): δ 9.42 (s, 2H), 8.35–8.13 (m, 4H), 8.33 (d, J = 7.5 Hz, 2H), 7.51–7.48 (m, 4H), 6.86 (d, J = 6.2 Hz, 2H), 6.50–6.40 (m, 4H), 5.01 (s, 4H), 2.90 (d, J = 7.0 Hz, 4H), 2.68 (t, J = 7.1 Hz, 4H), 2.29 (t, J = 7.1 Hz, 4H), 1.50 (s, 2H).

[0067] Example 3 Preparation of Organic Functional Molecules .

[0068] In addition to the preparation process of the target organic functional molecule in Example 1 Replace with The rest of the process is the same as in Example 1.

[0069] The target organic functional molecule obtained in this embodiment 1 The H NMR characterization data are as follows:

[0070] 1 ¹H NMR (300 MHz, dimethyl sulfoxide-d6): δ 9.42 (s, 2H), 8.33 (d, J = 7.5 Hz, 2H), 8.19–8.16 (m, 4H), 7.65 (t, J = 7.5 Hz, 2H), 7.55 (t, J = 7.5 Hz, 2H), 7.43–7.40 (m, 4H), 7.41 (s, 1H), 6.86 (d, J = 6.2 Hz, 2H), 6.50–6.40 (m, 4H), 5.01 (s, 4H), 2.90 (d, J = 7.0 Hz, 4H), 2.68 (t, J = 7.1 Hz, 4H), 2.29 (t, J = 7.1 Hz, 4H), 1.50 (s, 2H).

[0071] Example 4

[0072] Using the viologen derivatives prepared in Examples 1, 2 and 3 as organic functional molecules, single-molecule memristors based on viologen derivatives were prepared.

[0073] I. Pretreatment of the copper substrate, the process is as follows:

[0074] Take a long strip of copper sheet, about 10cm in length and about 1mm narrower than the quartz sheet. Then, after chamfering the four corners of the copper sheet, bend the edge of the copper sheet to match its shape with the back of the quartz sheet, thereby achieving mechanical fixation and obtaining a pretreated copper substrate.

[0075] II. Preparation of graphene film, the process is as follows:

[0076] The pretreated copper substrate was placed in a quartz boat in the CVD furnace chamber, positioned in the heating zone and kept out of contact with the furnace wall. The reaction chamber was then sealed, and the furnace vacuum was evacuated to a reference vacuum of approximately 1.6 Pa. The furnace temperature was raised to 1030 °C, and a mixture of H2 (flow rate of 16 sccm) and CH4 (flow rate of 0.8 sccm) gas was introduced and maintained for 40 min. The temperature was then lowered to room temperature to obtain a copper substrate with a graphene film grown on it.

[0077] III. The graphene film is transferred onto the silicon substrate, as follows:

[0078] A copper substrate carrying a graphene film was placed on a clean glass slide, and then polymethyl methacrylate (PMMA) was spin-coated onto it at 4000 rpm for 40 seconds. After coating, it was placed on a hot stage and heated to 180°C for 2 minutes to cure the PMMA. After cooling to room temperature, the copper substrate was removed and flipped so that the back side of the copper sheet was facing up. Then, the back side was etched using oxygen plasma.

[0079] Prepare three clean 200 Add 150 mL of pure water to each of the three petri dishes (labeled ①, ②, and ③), and add 10 mL of concentrated hydrochloric acid to petri dish ①. Mix well and set aside. Cut the previously treated copper sheet into small pieces and etch them in a 0.5 M ferric chloride solution for 4 hours until the copper sheet is completely etched away. Use a silicon wafer (1 cm × 1 cm × 700 μm) to lift the graphene film floating on the solution surface, transfer it to petri dish ①, and let it stand for 15 minutes. Then, use the same silicon wafer to transfer the graphene film to petri dishes ② and ③ in sequence, and let each dish stand for 15 minutes to complete the cleaning. Transfer the graphene film in petri dish ③ to another silicon wafer (1 cm × 1 cm × 700 μm), place it in a cool place to cure at room temperature for no less than 12 hours, then immerse it in acetone, heat it to 80 °C, and hold it for 8 minutes to completely dissolve and remove the PMMA. Then, transfer it to ethanol for cleaning and dry it with nitrogen to obtain a silicon substrate loaded with monolayer graphene.

[0080] IV. The process of preparing graphene electrode pairs using monolayer graphene is as follows:

[0081] Photoresist was coated onto the surface of a single-layer graphene at 4000 rpm for 60 seconds. After spin coating, the sample was pre-baked on a 120°C hot stage for 3 minutes. Subsequently, alignment marks were defined on the single-layer graphene using photolithography for 4 seconds. After exposure, the sample was developed using a 1:7 mixture of methyl isobutyl ketone and ultrapure water to obtain clear alignment marks.

[0082] The developed sample was placed in a substrate with a vacuum of 6 × 10⁻⁶. -4 Using a magnetron sputtering system, chromium (Cr) and gold (Au) layers were deposited sequentially. During chromium deposition, both pre-sputtering and main sputtering were performed at 50 W for 50 s and 150 s, respectively. At the same power of 50 W, gold was deposited, followed by pre-sputtering (30 s) and main sputtering (100 s), forming a Cr / Au bilayer metal film. The deposited sample was immersed in acetone and sonicated for 5 min. The metal not covered by the photoresist was removed using a lift-off process, retaining the gold markers, resulting in a graphene electrode array with gold markers.

[0083] Photoresist was spin-coated again on the sample surface (4000 rpm, 40 s), followed by pre-baking at 120°C for 3 min. Then, the strip pattern was photolithographically exposed for 4 minutes and developed with a developer solution of methyl isobutyl ketone and water at a volume ratio of 1:7. After forming the strip photoresist pattern, the sample was placed in a reactive-ion etching (RIE) system and etched with oxygen plasma for 45 s to remove the graphene not protected by the photoresist, resulting in a graphene structure protected by the strip pattern.

[0084] After cleaning the RIE-etched sample, the photoresist was spin-coated again (4000 rpm, 40 s), and pre-baked at 120°C for 3 min. The electrode pattern was then exposed for 4 s and developed with a developer solution of methyl isobutyl ketone and water at a volume ratio of 1:7 to obtain the graphene electrode array pattern.

[0085] PMMA electron beam photoresist was spin-coated onto the surface of a graphene electrode array (4000 rpm, 40 s), followed by baking at 180°C for 2 min to cure the film. Nanoscale gap patterns were defined using electron beam exposure, with gap sizes comparable to the length of a single viologen derivative molecule (organic functional molecule). After exposure, development was performed for approximately 18 s using a 1:3 volume ratio developer (a 1:7 volume ratio mixture of methyl isobutyl ketone and water) mixed with isopropanol, followed by rinsing and fixing with isopropanol to obtain the graphene electrode pair. A clear graphene nanostrip gap structure was observed under a 100x optical microscope.

[0086] The graphene electrode pair prepared above was placed in a dry three-necked glass bottle. Under an argon atmosphere, the organic functional molecules viologen derivative (1 mg) and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (3 mg) were added sequentially. Acetonitrile (20 mL) was then added to dissolve the graphene electrode pair. After soaking the graphene electrode pair for 48 h, it was removed with tweezers, washed with pure water, and dried with nitrogen to obtain a single-molecule memristor based on viologen derivative.

[0087] At room temperature and pressure, the obtained viologen-derived monomolecular memristor was placed on a probe stage, and its gold electrodes were electrically connected to the two source / measurement units of a semiconductor analyzer via a tungsten probe. The current response of the monomolecular memristor was detected using the analyzer's current-voltage (IV) scan module within a voltage range of -2V to +2V. The results are as follows: Figure 2 As shown.

[0088] Control group: Single-molecule memristors based on viologen cores, whose preparation process involves replacing the organic functional molecule viologen derivative with... The remaining preparation process is the same as above, and its IV characteristic curve is as follows: Figure 3 As shown.

[0089] from Figure 2 and Figure 3 It can be seen that the single-molecule memristor based on viologen derivatives provided by this invention has relatively stable performance, with an on / off ratio reaching 10. 3 Compared to the control group's on / off ratio (on / off ratio approximately 10), 2 It improves by an order of magnitude, and has a lower switching voltage and lower power consumption.

[0090] During voltage scanning, the molecular device provided by this invention exhibits significant current jumps at -1.5V and 1.8V. When the positive voltage scan reaches 1.8V, the viologen derivative molecule is reduced to a free radical state, and the device transitions from a low-resistivity state "0" to a high-resistivity state "1," resulting in a significant current jump. When the negative voltage scan reaches -1.5V, the viologen derivative molecule state reverses, and the device jumps back from the high-resistivity state "1" to the low-resistivity state "0," completing a stable switching between high and low resistance states. This result indicates that the current jump of the single-molecule memristor provided by this invention has a clear polarity dependence on the organic functional molecule viologen derivative.

[0091] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A single-molecule memristor based on viologen derivatives, characterized in that, include: A first electrode and a second electrode, wherein the first electrode and the second electrode form an electrode pair; An organic functional molecule, selected from viologen derivatives, has the following structural formula: ； Where R is selected from , and any one of them; The organic functional molecules are assembled between the electrode pairs via an amide condensation reaction.

2. The single-molecule memristor based on viologen derivatives as described in claim 1, characterized in that, The electrode pair is made of a single-layer graphene film.

3. The single-molecule memristor based on viologen derivatives as described in claim 1, characterized in that, The gap between the electrode pairs is at the nanometer level.

4. The single-molecule memristor based on viologen derivatives as described in claim 1, characterized in that, The electrode pair is a triangular electrode array point electrode.

5. The single-molecule memristor based on viologen derivatives as described in claim 1, characterized in that, The electrode pairs are connected to a single organic functional molecule.

6. A method for preparing a single-molecule memristor based on viologen derivatives, characterized in that, The method for preparing a single-molecule memristor based on viologen derivatives as described in any one of claims 1 to 5 comprises the following steps of assembling organic functional molecules with electrode pairs: Under inert gas conditions, an organic solution containing the organic functional molecule and the condensing agent is added to a container holding the electrode pair, and then pyridine is added. The reaction is carried out for at least 24 hours, so that the organic functional molecule is connected to the electrode pair through an amide bond, thereby obtaining a single-molecule memristor based on viologen derivatives.

7. The method for preparing a single-molecule memristor based on viologen derivatives as described in claim 6, characterized in that, The condensing agent is selected from 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride or N,N'-dicyclohexylcarbodiimide.

8. The method for preparing a single-molecule memristor based on viologen derivatives as described in claim 6, characterized in that, The organic solution is selected from acetonitrile.

9. The method for preparing a single-molecule memristor based on viologen derivatives as described in claim 6, characterized in that, The preparation of the electrode pair includes the following steps: S100. Graphene film is prepared on a copper substrate using chemical vapor deposition. S200: The graphene film is transferred onto a silicon substrate to obtain a silicon substrate loaded with a single layer of graphene. S300. A graphene electrode array with nano-gap is prepared on a silicon substrate carrying a single layer of graphene by photolithography, sputtering and etching processes to obtain the electrode pair.

10. The method for preparing a single-molecule memristor based on viologen derivatives as described in claim 9, characterized in that, In step S300, the etching process employs plasma etching technology.

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