A single-molecule optoelectronic device based on Fano resonance and its preparation method

Abstract

The present invention relates to the technical field of optoelectronic devices, and particularly to a single-molecule optoelectronic device based on Fano resonance and a preparation method thereof. The single-molecule optoelectronic switch of the optoelectronic device is self-assembled by a controllable charge separation group and a graphene dot electrode; the controllable charge separation group is selected from a single dicyanofluorene molecule, and the interaction between its strong electron-withdrawing group and electron-donating structure induces a destructive quantum interference effect, ensuring stable regulation within a small energy range to achieve a high switching ratio; an amide covalent bond is formed by –NH2 at the bottom of the dicyanofluorene molecule and –COOH at the end of the graphene dot electrode, significantly enhancing the chemical stability of the device and ensuring the long-term reliability of the single-molecule optoelectronic switch under complex operating conditions; at the same time, miniaturization of the size of the optoelectronic device is achieved; the preparation method provided by the present invention has a simple process, mild reaction conditions and is easy to operate, which is conducive to large-scale popularization and use.

Description

Technical Field

[0001] The present invention relates to the technical field of optoelectronic devices, and in particular to a single-molecule optoelectronic device based on Fano resonance and a preparation method thereof. Background Art

[0002] The semiconductor industry is facing the dilemma of gradually approaching the physical limit of the "top-down" manufacturing model, which limits the development of silicon-based chip manufacturing technology. With the continuous advancement of nanotechnology, the use of photoactive or electroactive single molecules as core components has become an ideal way to achieve chip miniaturization and multifunctionality.

[0003] In recent years, single-molecule devices have developed rapidly. Currently, a variety of functional devices including field-effect transistors, rectifiers, and light-emitting diodes have been constructed, which has promoted progress in this field. As the basic control unit in electronic circuits, the core function of switches is to control the on and off of current by switching states. Molecular switches, as a bistable quantum system, can switch between two different states when external conditions (such as light, electricity, heat, magnetism, etc.) change. These two states correspond to the on and off of the circuit due to the difference in conductance, thereby realizing the switching function.

[0004] Therefore, how to provide an optoelectronic device with stable performance and sensitive switching is a technical problem that urgently needs to be solved. Summary of the invention

[0005] The present invention aims to solve at least one of the technical problems existing in the related art. To this end, the first object of the present invention is to provide a single-molecule optoelectronic device based on Fano resonance; the second object of the present invention is to provide a method for preparing an optoelectronic device.

[0006] In order to achieve the first purpose, the technical solution adopted by the present invention is:

[0007] A single-molecule photoelectric device based on Fano resonance, comprising a single-molecule photoelectric switch, wherein the single-molecule photoelectric switch is self-assembled by a controllable charge separation group and a graphene dot electrode;

[0008] Wherein, the controllable charge separation group is selected from a single dicyanofluorene molecule, and its structural formula is as follows:

[0009] .

[0010] Charge capture refers to the phenomenon that specific groups or local defects capture electrons or holes and then retain them for a long time. Charge capture can affect the electrical behavior of the device by capturing carriers through specific groups or defects. Fano resonance is caused by the destructive quantum interference of a pair of delocalized and localized conductive molecular orbitals with opposite phases and equivalent energies, and exhibits a combination of antiresonance and resonance on the spectral line. In single-molecule photoelectric switches, Fano resonance allows effective modulation of electron transport between constructive and destructive interference within a small energy range to achieve a switching effect. The combination of charge capture and Fano resonance can enhance the effect of small energy level changes on electron transport, thereby achieving sensitive signal amplification.

[0011] Based on the above principle, by designing dicyanofluorene molecules containing controllable charge separation groups on the molecular trunk, making their overall energy level close to the electrode, charge separation and capture can be effectively promoted. Due to the high sensitivity of the Fano effect to small changes in energy levels, the energy level changes caused by charge capture are amplified through the Fano resonance effect, thereby significantly enhancing the change in conductance, thereby achieving efficient switching of single-molecule photoelectric switches.

[0012] Through the –NH 2 The amide covalent bond formed with the –COOH at the end of the graphene dot electrode significantly enhances the chemical stability of the device and ensures the long-term reliability of the single-molecule photoelectric switch under complex operating conditions.

[0013] Furthermore, the graphene point electrode is a graphene nanogap point electrode.

[0014] Furthermore, it also includes a dielectric layer, which includes a bottom aluminum oxide dielectric layer and a top hafnium oxide film, and the graphene point electrode is arranged on the hafnium oxide film.

[0015] Furthermore, the thickness of the aluminum oxide dielectric layer is 30 nm to 40 nm.

[0016] Furthermore, the thickness of the hafnium oxide film is 3 nm to 10 nm.

[0017] Furthermore, it also includes a protective layer, which covers the single-molecule photoelectric switch.

[0018] Furthermore, the protective layer is a hexagonal boron nitride (h-BN) protective layer; h-BN has atomic flatness and no dangling bonds, can reduce structural damage and related charge scattering caused by integration, and is a protective layer with excellent performance.

[0019] In order to achieve the second purpose, the technical solution adopted by the present invention is:

[0020] A method for preparing an optoelectronic device, for preparing any of the above-mentioned single-molecule optoelectronic devices based on Fano resonance, comprising the following steps:

[0021] S100, preparing an aluminum oxide dielectric layer on the silicon wafer by using a magnetron sputtering method, and preparing a hafnium oxide film on the aluminum oxide dielectric layer by using an atomic beam deposition method;

[0022] S200, preparing a single-layer graphene on the hafnium oxide film by chemical vapor deposition, and preparing a graphene dot electrode on the single-layer graphene by etching;

[0023] S300, adding a graphene dot electrode, a carboxyl activator and dicyanofluorene molecules to the reaction system, reacting for 36h to 72h under an inert gas atmosphere, so that the single dicyanofluorene molecule and the graphene dot electrode self-assemble to form a single-molecule photoelectric switch, thereby obtaining a single-molecule photoelectric device based on Fano resonance.

[0024] Further, in step S300, the excitation wavelength required for the switching ratio of the single-molecule photoelectric switch is determined using a femtosecond laser;

[0025] Femtosecond laser pulses in the corresponding band are used to excite the charge capture groups, drive charge separation and capture, and thus change the electrical properties of the molecules.

[0026] Furthermore, in step S300, the carboxyl activating agent is selected from 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride.

[0027] The above one or more technical solutions in the embodiments of the present invention have at least one of the following technical effects:

[0028] The present invention provides a single-molecule photoelectric device based on Fano resonance. The dicyanofluorene molecule is selected as the functional molecule of the single-molecule photoelectric switch. The strong electron-withdrawing group and the electron-donating structure interact with each other to induce the destructive quantum interference effect, thereby ensuring stable regulation within a small energy range to achieve a high switching ratio. The -NH 2 The amide covalent bond formed with the –COOH at the end of the graphene point electrode significantly enhances the chemical stability of the device and ensures the long-term reliability of the single-molecule photoelectric switch under complex operating conditions; at the same time, it achieves the miniaturization of the size of the photoelectric device.

[0029] The invention provides a method for preparing a photoelectric device, which has a simple process, mild reaction conditions, is easy to operate, and is easy to promote and use on a large scale.

[0030] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the structure of a single-molecule optoelectronic device based on Fano resonance provided in an embodiment of the present invention.

[0032] Figure 2 It is a partial enlarged view of the controllable charge separation group provided in an embodiment of the present invention.

[0033] Figure 3 This is the I / V characteristic curve of the single-molecule optoelectronic device based on Fano resonance provided in Example 2 of the present invention tested under the conditions of no light and gate voltage.

[0034] Figure 4 This is a characteristic curve of the current varying with the gate voltage of the single-molecule optoelectronic device based on Fano resonance provided in Example 2 of the present invention when tested at a bias voltage of 0.1 V.

[0035] Figure 5 It is the It characteristic curve of the current varying with time tested under a bias voltage of 0.1 V and 500 nm laser irradiation provided in Example 2 of the present invention. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme of the present invention will be clearly and completely described below in conjunction with the drawings in the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention. The following embodiments are used to illustrate the present invention, but cannot be used to limit the scope of the present invention.

[0037] A single-molecule optoelectronic device based on Fano resonance, such as Figure 1 and Figure 2 As shown, it includes a single-molecule photoelectric switch, which is self-assembled by a controllable charge separation group 1 and a graphene point electrode 2;

[0038] Wherein, the controllable charge separation group is selected from a single dicyanofluorene molecule, and its structural formula is as follows:

[0039] ;

[0040] Preferably, the graphene point electrode is a graphene nanogap point electrode.

[0041] According to a specific embodiment provided by the present invention, it also includes a dielectric layer 3, the dielectric layer 3 includes a bottom aluminum oxide dielectric layer and a top hafnium oxide film, and the graphene point electrode is arranged on the hafnium oxide film;

[0042] Preferably, the thickness of the aluminum oxide dielectric layer is 30 nm to 40 nm;

[0043] Preferably, the thickness of the hafnium oxide film is 3 nm to 10 nm;

[0044] According to a specific embodiment provided by the present invention, it also includes a protective layer, and the protective layer covers the single-molecule photoelectric switch;

[0045] Preferably, the protective layer is a hexagonal boron nitride protective layer.

[0046] In the following examples, the experimental methods used are conventional methods unless otherwise specified, and the materials, reagents, etc. used are all commercially available unless otherwise specified.

[0047] Example 1 Preparation of a dicyanofluorene compound containing a tert-butyloxycarbonyl (Boc) protecting group.

[0048] Its structural formula is as follows:

[0049]

[0050] The preparation process of the above-mentioned dicyanofluorene compound containing a protecting group is as follows:

[0051] In a nitrogen atmosphere without water or oxygen, add (2mmol), (6mmol)、Pd(PPh 3 ) 4 (0.1mmol), 10ml K 2 CO 3 (20 mmol) aqueous solution and toluene (250 ml), nitrogen was introduced at 90 ° C, the reaction was carried out for 24 hours, cooled, the reactant was poured into water, and extracted with dichloromethane (100 ml) three times, the excess solvent was removed, and purified by column chromatography to obtain ;

[0052] 1 H NMR (500 MHz, chloroform- d ): δ 8.85 (s, 1H), 8.68 (s, 1H), 7.52 (s, 1H), 7.34 (s, 1H), 1.57 – 1.11 (m, 22H), 0.88 (dt, J = 15.2, 6.8 Hz, 12H). 13 C NMR (125 MHz, chloroform- d) δ 161.99, 154.26, 149.49, 148.36, 148.31, 148.28, 147.37,145.43, 143.88, 141.97, 139.84, 138.11, 132.85, 130.15, 129.81, 128.35,118.36, 112.45, 39.35, 36.83, 30.69, 29.32, 23.04, 21.84, 14.04, 11.27;

[0053] HRMS (TOF-ESI+) (m / z): C 34 H 38 Br 2 N 6 S 4 Si 844.02.

[0054] In a nitrogen atmosphere without water or oxygen, add (2mmol), (1.8mmol)、Pd(dppf) 2 Cl 2 (0.04 mmol), KOAc (20 mmol) and dioxane (250 ml), refluxed for 24 h under nitrogen atmosphere, cooled, and excess solvent was removed, then purified by column chromatography and separated to obtain ;

[0055] 1 H NMR (500 MHz, chloroform- d ): δ 8.93 (s, 1H), 8.76 (s, 1H), 7.54 (s, 1H), 7.39 (s, 1H), 1.49 – 1.14 (m, 46H), 0.88 (dt, J = 15.2, 6.8 Hz, 12H). 13 C NMR (125 MHz, chloroform- d) δ 167.01, 156.01, 153.57, 150.28, 148.36, 148.31, 147.36,145.81, 144.22, 141.50, 140.12, 133.10, 132.81, 130.15, 129.70, 128.33,120.43, 118.33, 83.78, 83.77, 39.35, 36.83, 30.69, 29.32, 24.84, 23.04,21.84, 14.04, 11.27.

[0056] HRMS (TOF-ESI+) (m / z): C 46 H 62 Br 2 N 6 O 4 S 4 Si 940.37.

[0057] In a nitrogen atmosphere without water or oxygen, add (1.5 mmol), (3 mmol), 0.04 mmol of Pd(PPh 3 ) 4 , 10 ml K 2 CO 3 (20mmol) aqueous solution and toluene (250ml), refluxed for 24h under nitrogen atmosphere, cooled, poured into water, extracted three times with dichloromethane (100ml), removed excess solvent, and then purified by column chromatography to obtain ;

[0058] 1 H NMR (500 MHz, chloroform- d ): δ 9.08 (d, J = 6.4 Hz, 2H), 7.80 (d, J = 6.6 Hz,1H), 7.69 – 7.63 (m, 2H), 7.60 (d, J = 6.8 Hz, 1H), 7.53 (s, 1H), 7.36 (s, 1H), 7.15 (d, J = 6.2 Hz, 1H), 7.10 (d, J = 6.4 Hz, 1H), 7.05 (d, J= 6.2 Hz, 2H), 1.58– 1.08 (m, 22H), 0.88 (dt, J = 15.2, 6.8 Hz, 12H);

[0059] 13 C NMR (125 MHz, chloroform- d ): δ 155.76, 155.34, 148.36, 148.31, 147.40,147.39, 145.56, 144.71, 144.23, 144.18, 142.85, 142.47, 141.23, 139.92,137.80, 137.69, 137.56, 137.46, 132.85, 130.80, 130.75, 130.15, 129.81,129.49, 128.35, 127.31, 126.98, 126.15, 124.92, 124.88, 120.20, 119.47,111.69, 111.62, 39.35, 36.83, 30.69, 29.32, 23.04, 21.84, 14.04, 11.27;

[0060] HRMS (TOF-ESI+) (m / z): C 50 H 46 Br 2 N 6 O 4 S 8 Si 1171.97.

[0061] In a nitrogen atmosphere without water or oxygen, add (1.5mmol), (2 mmol), 0.04 mmol of Pd(PPh 3 ) 4 , and 10 ml K 2 CO 3 (20 mmol) aqueous solution and toluene (250 ml), refluxed for 24 h under nitrogen atmosphere, cooled, poured into water, and extracted three times with dichloromethane (100 ml), removed excess solvent, and then purified by column chromatography to obtain .

[0062] 1 H NMR (500 MHz, chloroform- d ): δ 9.08 (d, J= 6.4 Hz, 2H), 7.84 (d, J = 6.8 Hz,1H), 7.69 – 7.60 (m, 2H), 7.57 (d, J = 6.8 Hz, 1H), 7.56 – 7.49 (m, 3H), 7.37(d, J = 6.1 Hz, 2H), 7.29 (d, J = 6.4 Hz, 1H), 7.18 (dt, J = 7.5, 1.1 Hz, 2H), 7.10(d, J = 6.4 Hz, 1H), 7.05 (d, J = 6.2 Hz, 1H), 5.20 (t, J = 4.9 Hz, 1H), 3.17 (td, J = 5.6, 4.8 Hz, 2H), 2.65 (tt, J = 7.9, 1.0 Hz, 2H), 1.82 (tt, J = 7.8, 5.7 Hz,2H), 1.47 – 1.15 (m, 31H), 0.88 (dt, J = 15.2, 6.8 Hz, 12H);

[0063] 13 C NMR (125 MHz, chloroform- d): δ 156.39, 155.76, 155.34, 148.36, 148.31,147.40, 147.39, 145.56, 144.71, 144.21, 144.18, 143.10, 142.85, 142.47,142.34, 141.23, 139.92, 138.44, 137.87, 137.56, 137.46, 134.00, 132.85,130.75, 130.15, 129.81, 129.44, 128.58, 128.35, 127.31, 126.98, 126.67,126.00, 124.88, 124.63, 124.22, 120.20, 119.47, 111.62, 79.54, 40.36, 39.35,36.83, 33.58, 30.69, 29.99, 29.32, 28.30, 23.04, 21.84, 14.04, 11.27;

[0064] HRMS (TOF-ESI+) (m / z): C 64 H 66 Bn 7 O 2 S 8 Si 1327.20.

[0065] In a nitrogen atmosphere without water or oxygen, add

[0066] (1.5mmol), (2 mmol), 0.04 mmol of Pd(PPh 3 ) 4 , 10 ml K 2 CO 3 (20 mmol) aqueous solution and toluene (250 ml) were refluxed under nitrogen atmosphere for 24 h. After cooling, the reactant was poured into water and extracted three times with dichloromethane (100 ml) to remove excess solvent. Then, it was purified by column chromatography to obtain

[0067] ;

[0068] 1 H NMR (500 MHz, chloroform- d ): δ 9.08 (d, J = 6.4 Hz, 2H), 8.15 (d, J= 2.1Hz, 1H), 8.09 (d, J = 2.3 Hz, 1H), 8.04 (dd, J = 8.1, 2.6 Hz, 2H), 7.84 (d, J = 6.8Hz, 1H), 7.75 (dd, J = 8.0, 2.3 Hz, 1H), 7.71 (d, J = 6.2 Hz, 1H), 7.68 – 7.63(m, 2H), 7.63 – 7.56 (m, 3H), 7.55 – 7.50 (m, 3H), 7.48 (d, J = 6.4 Hz, 1H),7.41 (d, J = 6.4 Hz, 1H), 7.37 (d, J = 6.3 Hz, 2H), 7.29 (d, J = 6.4 Hz, 1H), 7.19(ddt, J = 7.1, 6.1, 1.0 Hz, 4H), 5.20 (t, J = 4.9 Hz, 2H), 3.17 (td, J = 5.6, 4.8Hz, 4H), 2.65 (tq, J = 7.9, 1.1 Hz, 4H), 1.82 (tt, J = 7.9, 5.7 Hz, 4H), 1.51 –1.11 (m, 40H), 0.88 (dt, J = 15.2, 6.8 Hz, 12H);

[0069] 13 C NMR (125 MHz, chloroform- d): δ 157.61, 156.83, 156.50, 151.84, 148.82,147.65, 146.43, 146.37, 145.11, 145.02, 144.95, 143.96, 143.85, 143.56,143.49, 142.94, 142.76, 142.74, 142.44, 142.41, 140.35, 139.31, 139.23,139.15, 138.50, 138.19, 137.66, 135.47, 134.83, 134.79, 33.59, 125.92, 125.58, 125.56, 125.25,124.88, 124.84, 124.79, 123.24, 121.84, 115.26, 79.55, 76.22, 40.22, 39.60,38.05, 33.59, 32.77, 29.66, 29.23, 28.30, 23.03, 19.00, 14.04, 11.17;

[0070] HRMS (TOF-ESI+) (m / z): C 94 H 92 N 10 O 4 S 8 Si 1708.48.

[0071] Example 2 Preparation of single-molecule optoelectronic devices based on Fano resonance.

[0072] 1. Preparation of dielectric layer:

[0073] Spin-coat photoresist on a silicon wafer covered with 300nm silicon oxide, and use a photolithography machine to photolithography the access electrode to obtain the first film, which is mainly used for the subsequent needle test and photolithography calibration of the experiment; then, use thermal evaporation to first evaporate 6nm of chromium and then evaporate 30nm of gold on the above film, and remove the excess photoresist with acetone to obtain the access electrode;

[0074] Spin-coat photoresist on the lead electrode, perform photolithography on the gate, and obtain a bottom gate; plate a 30nm aluminum film on the surface of the bottom gate by magnetron sputtering, and use the aluminum film as the gate to apply gate voltage; then soak the bottom gate in an acetone solution to remove the resist, and obtain a dielectric layer of aluminum oxide;

[0075] A 5 nm hafnium oxide film is deposited on the aluminum oxide surface of the dielectric layer by atomic beam deposition to obtain a dielectric layer.

[0076] 2. Preparation of graphene point electrode, the process is as follows:

[0077] A single-layer graphene is obtained by chemical vapor deposition, and the single-layer graphene is attached to a clean quartz plate with a transparent tape, and polymethyl methacrylate (PMMA) is spin-coated on the single-layer graphene, and the spin coating is performed at a speed of 4000 revolutions per minute for 40 seconds using a glue spreader, and the glue is baked at 180°C for 2 minutes on a heating table; the excess PMMA and graphene on the back of the copper foil are etched by oxygen plasma to obtain a PMMA-single-layer graphene-copper foil structure;

[0078] The PMMA-single-layer graphene-copper foil was cut into 1 cm × 1 cm small pieces, placed in a ferric chloride solution, and the copper foil on the back was dissolved to obtain a PMMA-supported single-layer graphene film;

[0079] After the copper foil is completely removed, the PMMA-supported single-layer graphene film is immersed in a hydrochloric acid solution, an aqueous solution, and a potassium hydroxide solution, and finally transferred to the dielectric layer prepared above, and PMMA is removed by heating with acetone at 120° C. to obtain a graphene dielectric layer;

[0080] Photolithography strips on the graphene dielectric layer, and removing excess single-layer graphene by oxygen plasma etching to obtain a substrate having graphene strips;

[0081] 8nm chromium and 60nm gold were successively deposited on the above-mentioned film by thermal evaporation, and the photoresist was removed by soaking in acetone to obtain a graphene array electrode; the conductivity of the graphene array electrode was tested at a voltage of 50 mV, and the graphene array electrode with a conductivity of the order of 10 μA was screened out for subsequent experiments.

[0082] 3. Preparation of graphene point electrode, the process is as follows:

[0083] A dotted line with a length of 150 nm and a width of 5 nm is etched on the above-selected graphene array electrode by electron beam exposure to obtain a graphene dot electrode;

[0084] The graphene point electrodes are etched with oxygen plasma, and each pair of electrodes is tested for continuity using a probe station and a source meter. After repeating this step multiple times, graphene nanogap point electrodes are obtained.

[0085] 4. Preparation of single-molecule photoelectric switch, the process is as follows:

[0086] The dicyanofluorene compound containing a Boc protecting group prepared in Example 1 (1 mg) was placed in a two-necked flask, and then dichloromethane (5 ml) and trifluoroacetic acid (0.5 ml) were injected into the flask. The mixture was reacted for 2 h under a nitrogen atmosphere, and the trifluoroacetic acid was removed by a sodium hydroxide solution having a mass concentration of 0.5%, to obtain a dicyanofluorene compound solution having the Boc protecting group removed.

[0087] The dicyanofluorene compound solution was subjected to rotary evaporation at a rotation speed of 80 rpm and a vacuum degree of 70 hPa at room temperature for 30 min to remove the dichloromethane solvent and obtain a dicyanofluorene compound without the Boc protecting group; the dicyanofluorene compound was placed in a nitrogen atmosphere by ventilation operation, and 10 ml of anhydrous pyridine was injected to dissolve the dicyanofluorene compound pyridine solution;

[0088] The graphene point electrode was placed in a two-necked flask, and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (50×10 −4 M, 5 ml) and a pyridine solution (5 ml) of a dicyanofluorene compound without the Boc protecting group were reacted in a nitrogen atmosphere for 48 h. The –NH2 at the bottom of the dicyanofluorene molecule and the –COOH at the end of the graphene point electrode formed an amide covalent bond to obtain a single-molecule photoelectric switch. The device was taken out from the two-necked flask, rinsed three times with deionized water and ethanol respectively, and dried with nitrogen to obtain a single-molecule photoelectric device based on Fano resonance.

[0089] The results of the I / V characteristic curve test of the above-mentioned single-molecule optoelectronic device based on Fano resonance are as follows: Figure 3 As shown; when the bias voltage is 0.1V, the characteristic diagram of the current changing with the gate voltage is as follows Figure 4 As shown, the results show that under the condition of constant bias voltage, the conductivity of the optoelectronic device changes with the gate voltage regulation, and exhibits a line shape combining resonance and anti-resonance, realizing the switching function;

[0090] Figure 3 and Figure 4 The results show that the dicyandiamide molecules are successfully connected between graphene nanogap point electrodes, and the performance of the optoelectronic device can be regulated by the gate voltage.

[0091] Under 500 nm laser irradiation and 0.1 V bias, the It characteristic diagram of the current change over time of the above-mentioned single-molecule optoelectronic device based on Fano resonance is shown in Figure 5 As shown, the results show that the conductivity of the photoelectric device is significantly enhanced under illumination in this band, and it has a highly sensitive photoelectric response. In the figure, light refers to the effect of light on current, and darkness refers to the current state under no light conditions.

[0092] During laser irradiation, a pump-probe method is used to excite molecules to an excited state by pumping light, and then use probe light to detect the dynamic evolution of the excited state after a certain time delay, which can effectively determine the optimal excitation wavelength that can achieve the highest switching ratio.

[0093] Specifically, the propagation path of the femtosecond laser is as follows: the femtosecond laser pulse is divided into two beams through the first reflector and the semi-transparent and semi-reflective mirror. One beam of light is converted into a pump light of a specific wavelength through a broadband optical parametric amplifier, and then irradiated onto the single-molecule photoelectric switch after passing through the second reflector, the third reflector, the fourth reflector, the fifth reflector and the sixth reflector; at the same time, the second beam of light is converted into a detection light of a specific wavelength through a broadband optical parametric amplifier, and then realizes a picosecond time delay τ relative to the pump light through a time delay platform, and then irradiates the single-molecule photoelectric switch after passing through the fifth reflector and the sixth reflector.

[0094] Among them, a pump light of a specific wavelength is used to excite the molecule from the ground state to the first excited state, and the change of the device conductivity is monitored. At the same time, the reflected pump light is input into the spectrometer for absorption spectrum measurement to obtain the energy information of the first excited state. Based on the charge capture effect, the conductivity change of the photoelectric device reflects the charge capture of the corresponding excited state. Combined with the spectral data of the pump light absorption, the corresponding excited state can be effectively monitored and guidance can be provided for optimizing the switching ratio. Further, after a time delay τ of the picosecond scale, the probe light of a specific wavelength excites the molecule to the second excited state again. The absorption of the probe light is measured by the spectrometer to obtain the energy information of the second excited state and the energy difference between the first excited state and the second excited state; by monitoring the change of the electrical signal, the conductivity characteristics in the second excited state can be further analyzed. Based on this, the wavelengths of the pump light and the probe light are gradually adjusted, and the above process is repeated to continuously monitor the change of the device conductivity and the light absorption spectrum, and finally the optimal excitation wavelength that can achieve the maximum switching ratio is selected. Excitation using femtosecond laser pulses of the corresponding band can significantly improve the response speed of the device, ensure its efficient adaptability in complex application scenarios, and achieve ultra-high switching ratio and ultra-fast response performance.

[0095] At the same time, during the test process, the switching characteristics of the single-molecule photoelectric switch are regulated by changing the test temperature, gate voltage, and source-drain bias using a comprehensive physical property measurement system (PPMS), and applying ultrafast light to the device using a femtosecond laser, thereby further improving the switching ratio and switching response speed.

[0096] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A single-molecule optoelectronic device based on Fano resonance, characterized in that: It includes a single-molecule photoelectric switch, which is self-assembled by a controllable charge separation group and a graphene point electrode; Wherein, the controllable charge separation group is selected from a single dicyanofluorene molecule, and its structural formula is as follows: 。 2. The single-molecule optoelectronic device based on Fano resonance according to claim 1, characterized in that: The graphene point electrode is a graphene nanogap point electrode.

3. The single-molecule optoelectronic device based on Fano resonance according to claim 1, characterized in that: It also includes a dielectric layer, which includes an aluminum oxide dielectric layer at the bottom layer and a hafnium oxide film at the top layer, and the graphene point electrode is arranged on the hafnium oxide film.

4. The single-molecule optoelectronic device based on Fano resonance according to claim 3, characterized in that: The thickness of the aluminum oxide dielectric layer is 30 nm to 40 nm.

5. The single-molecule optoelectronic device based on Fano resonance according to claim 3, characterized in that: The thickness of the hafnium oxide film is 3nm-10nm.

6. The single-molecule optoelectronic device based on Fano resonance according to claim 1, characterized in that: It also includes a protective layer, which covers the single-molecule photoelectric switch.

7. The single-molecule optoelectronic device based on Fano resonance according to claim 6, characterized in that: The protective layer is a hexagonal boron nitride protective layer.

8. A method for preparing a photoelectric device, characterized in that: The method for preparing a single-molecule optoelectronic device based on Fano resonance as claimed in any one of claims 1 to 7 comprises the following steps: S100, preparing an aluminum oxide dielectric layer on the silicon wafer by using a magnetron sputtering method, and preparing a hafnium oxide film on the aluminum oxide dielectric layer by using an atomic beam deposition method; S200, preparing a single-layer graphene on the hafnium oxide film by chemical vapor deposition, and preparing a graphene dot electrode on the single-layer graphene by etching; S300, adding a graphene dot electrode, a carboxyl activator and dicyanofluorene molecules to the reaction system, reacting for 36h to 72h under an inert gas atmosphere, so that the single dicyanofluorene molecule and the graphene dot electrode self-assemble to form a single-molecule photoelectric switch, thereby obtaining a single-molecule photoelectric device based on Fano resonance.

9. The method for preparing a photoelectric device according to claim 8, characterized in that: In step S300, the excitation wavelength required for the switching ratio of the single-molecule photoswitch is determined using a femtosecond laser.

10. The method for preparing a photoelectric device according to claim 8, characterized in that: In step S300, the carboxyl activating agent is selected from 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride.

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