Single-molecule device based on femtosecond two-photon absorption and two-color light source and preparation method thereof

Abstract

The present invention relates to the technical field of optoelectronic devices, and particularly to a two-color light source single-molecule device based on femtosecond two-photon absorption and a preparation method thereof. The single-molecule device includes a substrate, a graphene source electrode, and a graphene drain electrode. The graphene source electrode and the graphene drain electrode form a graphene electrode pair, and the graphene electrode pair is disposed on the top layer of the substrate. The two-color light source uses a multi-thienyl dendritic molecule of a single-molecule perylene diimide core as a luminescent molecule. The two -NH2 ends of the multi-thienyl dendritic molecule of the perylene diimide core are respectively connected to the graphene source electrode and the graphene drain electrode through amide bonds, significantly enhancing the chemical stability of the single-molecule device, and thus being able to ensure its long-term reliability under complex operating conditions. The preparation method of the two-color light source single-molecule device based on femtosecond two-photon absorption provided by the present invention has a simple operation process and controllable conditions, which is beneficial to the large-scale production of single-molecule devices.

Description

Technical Field

[0001] The present invention relates to the technical field of optoelectronic devices, and particularly to a two-color light source single-molecule device based on femtosecond two-photon absorption and a preparation method thereof. Background Art

[0002] In recent years, the rapid development of quantum information science and nanotechnology has provided broad prospects for the design and application of novel optoelectronic devices. Among them, two-photon absorption (TPA), as an important nonlinear optical effect, has shown great potential in the field of single-molecule devices due to its unique photon-matter interaction mechanism. Two-photon absorption involves the process in which two low-energy photons are simultaneously absorbed and excite electrons to transition to higher energy levels. Compared with single-photon absorption, TPA has deeper light penetration ability, higher spatial resolution, and selective response to specific wavelengths, making it have important application values in fields such as biological imaging, optical data storage, and quantum information processing.

[0003] However, in practical applications, the efficiency of the two-photon absorption effect is limited by various factors, including the optical properties of materials, the wavelength and intensity matching of light sources, etc. Especially for single-molecule devices, the efficiency of TPA is usually low and is easily affected by environmental noise and nonlinear losses. Traditional light source systems usually use single-wavelength high-intensity lasers to excite TPA, but this method has problems such as large energy loss, limited wavelength range, and high risk of material damage. In addition, the optical response characteristics of single-molecule devices are highly dependent on the wavelength and intensity of the light source, and it is difficult for existing technologies to achieve precise control and optimization of the TPA effect.

[0004] To solve the above problems, recent research has focused on developing novel two-color light source systems, that is, using two photons with different wavelengths to cooperate to achieve efficient two-photon absorption. Two-color light sources can not only reduce the demand for single-wavelength high intensity, reduce material damage and energy loss, but also optimize the TPA effect by precisely regulating the wavelength combination and relative intensity. In addition, the application of two-color light source systems in single-molecule devices is expected to achieve dynamic regulation of photon absorption, providing technical support for multi-modal switching and efficient operation of device functions. Nevertheless, the existing technologies still face the following challenges: the coupling efficiency between two-color light source systems and single-molecule devices is low; there is a lack of wavelength and intensity optimization methods for specific molecular systems; the optical response stability and scalability of devices are difficult to meet the actual application requirements.

[0005] Therefore, there is an urgent need to develop a novel two-color light source single-molecule device for two-photon absorption to achieve efficient, stable, and controllable photon absorption and energy conversion, and promote its application in fields such as quantum information processing and nanophotonics. Summary of the Invention

[0006] The present invention aims to solve at least one of the technical problems existing in the related art. For this reason, the first object of the present invention is to provide a single-molecule device with a two-color light source based on femtosecond two-photon absorption; the second object of the present invention is to provide a preparation method for the single-molecule device with a two-color light source based on femtosecond two-photon absorption.

[0007] In order to achieve the first object, the technical solution adopted by the present invention is as follows:

[0008] A single-molecule device with a two-color light source based on femtosecond two-photon absorption includes:

[0009] A substrate, a graphene source electrode, and a graphene drain electrode. The graphene source electrode and the graphene drain electrode form a pair of graphene electrodes, and the pair of graphene electrodes is disposed on the top layer of the substrate;

[0010] A two-color light source, where the two-color light source uses a multi-thiophene-based dendritic molecule of a single-molecule perylene diimide core as a luminescent molecule, and the two -NH 2 ends of the multi-thiophene-based dendritic molecule of the perylene diimide core are respectively connected to the graphene source electrode and the graphene drain electrode through amide bonds;

[0011] Among them, the structural formula of the multi-thiophene-based dendritic molecule of the perylene diimide core is as follows:

[0012] ;

[0013] By means of a chemical decoupling method, a multi-thiophene-based dendritic molecule of a single-molecule perylene diimide core is assembled between the graphene source electrode and the graphene drain electrode to form a two-color light source. The electro-pumping and femtosecond laser are used to modulate the luminescent characteristics of the molecule. By changing the wavelength and delay characteristics of the femtosecond laser, the conversion between the single-photon absorption and two-photon absorption of the molecule can be achieved, thereby changing the molecular radiative transition characteristics. The combination of electro-luminescence and femtosecond laser modulation can induce the two-color luminescence of the multi-thiophene-based dendritic molecule of the single-molecule perylene diimide core, thereby realizing a two-color light source at the molecular scale. This two-color light source has unique optical and quantum characteristics and has broad application prospects in the quantum field, and is expected to solve technical problems such as multi-mode quantum state encoding in quantum communication.

[0014] Further, the graphene source electrode and the graphene drain electrode are nano-gap point electrodes.

[0015] Further, it further includes a packaging layer, and the packaging layer covers the pair of graphene electrodes and the two-color light source.

[0016] Further, the packaging layer is selected from hexagonal boron nitride materials.

[0017] Further, the material of the substrate is selected from silicon wafers.

[0018] To achieve the second object, the technical solution adopted by the present invention is as follows:

[0019] A preparation method of a single-molecule device with a two-color light source based on femtosecond two-photon absorption, which is used to prepare the single-molecule device with a two-color light source based on femtosecond two-photon absorption described in any one of the above, includes the following steps:

[0020] S100. Prepare a graphene array electrode on a substrate;

[0021] S200. Construct a graphene source electrode and a graphene drain electrode on the graphene array electrode;

[0022] S300. Immerse the graphene source electrode and the graphene drain electrode in a pyridine solution of a polythiophene-based dendritic compound containing a perylene diimide core with a condensing agent, so that the single-molecule perylene diimide core-based polythiophene-based dendritic molecules self-assemble between the graphene source electrode and the graphene drain electrode to obtain a single-molecule device with a two-color light source based on femtosecond two-photon absorption.

[0023] Further, in step S300, the concentration of the pyridine solution of the polythiophene-based dendritic compound containing a perylene diimide core is not less than 0.25 mM.

[0024] Further, in step S300, the condensing agent is selected from 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride.

[0025] Further, the emission spectrum of the single-molecule device with a two-color light source based on femtosecond two-photon absorption obtained in step S300 is detected by stochastic optical reconstruction microscopy.

[0026] Further, the femtosecond excitation photons of the single-molecule device with a two-color light source based on femtosecond two-photon absorption are in the wavelength range of 1160 - 1630 nm, and the molecular emission peak is in the wavelength range of 200 nm - 450 nm.

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

[0028] The single-molecule device with a two-color light source based on femtosecond two-photon absorption provided by the present invention has a two-color light source in the single-molecule device formed by self-assembling single-molecule perylene diimide core-based polythiophene-based dendritic molecules. The structure of the perylene diimide core-based polythiophene-based dendritic molecules contains controllable charge separation groups. Through electro-pump excitation and joint regulation of femtosecond laser, the single / double-photon absorption conversion of the molecules is realized, inducing the molecules to absorb photons with different energies and then transition to emit light, realizing the light emission of a light-emitting diode (LED); the amino groups -NH at both ends of the single-molecule perylene diimide core-based polythiophene-based dendritic molecules2 It forms amide covalent bonds with the carboxyl - COOH at the ends of the graphene source - terminal electrode and the drain - terminal electrode, significantly enhancing the chemical stability of the single - molecule device, and thus being able to ensure its long - term reliability under complex operating conditions; the graphene source - terminal electrode and the graphene drain - terminal electrode are nano - gap point electrodes, enabling miniaturization of the size of the single - molecule device.

[0029] The preparation method of the single - molecule device with a two - color light source based on femtosecond two - photon absorption provided by the present invention has a simple operation process and controllable conditions, which is conducive to the large - scale production of the device.

[0030] Additional aspects and advantages of the present invention will be given in part in the following description, will become apparent in part from the following description, or will be understood through the practice of the present invention. Description of the Drawings

[0031] Figure 1 It is a schematic structural diagram of the single - molecule device with a two - color light source based on femtosecond two - photon absorption provided in Embodiment 2 of the present invention.

[0032] Figure 2 It is the molecular emission spectrum of the single - molecule device with a two - color light source based on femtosecond two - photon absorption provided in Embodiment 2 of the present invention when the wavelength is 1160 nm.

[0033] Figure 3 It is the molecular emission spectrum of the single - molecule device with a two - color light source based on femtosecond two - photon absorption provided in Embodiment 2 of the present invention when the wavelength is 1630 nm.

[0034] Reference Signs:

[0035] 1, Substrate; 2, Graphene drain - terminal electrode; 3, Graphene source - terminal electrode; 4, Two - color light source; 5, Encapsulation layer. Detailed Embodiments

[0036] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall 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] In the following embodiments, the experimental methods used are all conventional methods unless otherwise specified, and the materials, reagents, etc. used are carried out according to the techniques or conditions described in the literature in this field or according to the product specifications. Unless otherwise specified, they can all be obtained from commercial channels.

[0038] As Figure 1 shown, a single-molecule device with a two-color light source based on femtosecond two-photon absorption includes:

[0039] a substrate 1, a graphene source-terminal electrode 2, and a graphene drain-terminal electrode 3. The graphene source-terminal electrode 2 and the graphene drain-terminal electrode 3 form a graphene electrode pair, and the graphene electrode pair is disposed on the top layer of the substrate;

[0040] a two-color light source 4, where the two-color light source 4 uses a polythiophene-based dendritic molecule of a single-molecule perylene diimide core as a luminescent molecule, and two -NH 2 ends of the polythiophene-based dendritic molecule of the perylene diimide core are respectively connected to the graphene source-terminal electrode and the graphene drain-terminal electrode through amide bonds;

[0041] wherein, the structural formula of the polythiophene-based dendritic molecule of the perylene diimide core is as follows:

[0042] .

[0043] In some embodiments of the present invention, the graphene source-terminal electrode 2 and the graphene drain-terminal electrode 3 are nano-gap point electrodes.

[0044] In some embodiments of the present invention, it further includes a packaging layer 5, and the packaging layer 5 covers the graphene electrode pair and the two-color light source 4.

[0045] In some embodiments of the present invention, the packaging layer 5 is selected from hexagonal boron nitride materials.

[0046] In some embodiments of the present invention, the material of the substrate is selected from silicon wafers.

[0047] Example 1

[0048] A polythiophene-based dendritic compound of a perylene diimide core, whose molecular structural formula is as follows:

[0049]

[0050] I. Synthesis of Compound III , the process is as follows:

[0051] Under an argon atmosphere, magnesium chips (75 mmol), anhydrous ether (10 ml), and an ether solution (30 mL) containing Compound I (60 mmol) were successively added to a three-necked flask, mixed evenly, heated to 45 °C, and refluxed for 3 h until the magnesium chips were completely dissolved. The obtained Grignard reagent was transferred to a dropping funnel.

[0052] Another dry three-necked flask was taken, and anhydrous ether (40 mL) and Compound II (20 mmol) and nickel(II) dichloride bis(diphenylphosphino)propane (0.2 mmol), and the system was purged with argon three times; the system was cooled to 0 °C (ice-water bath), and the Grignard reagent prepared above was slowly added dropwise (controlling the dropping rate at 1 - 2 drops / second to avoid local overheating). After the addition was complete, the temperature was gradually raised to 45 °C, and the reaction was refluxed for 6 h. The reaction progress was monitored by TLC, and the developing solvent for TLC was a mixture of petroleum ether and ethyl acetate (volume ratio 10:1). The reaction solution was cooled to 0 °C, and dilute hydrochloric acid (10% v / v, 30 mL) was slowly added dropwise to quench the reaction. The layers were separated, the aqueous phase was extracted with diethyl ether (20 mL × 3), the organic phases were combined, washed with saturated sodium bicarbonate solution (20 mL × 2) until neutral, dried over anhydrous sodium sulfate, filtered, and concentrated under reduced pressure to obtain the crude product.

[0053] The above crude product was purified by silica gel column chromatography, and the target fraction was collected. After rotary evaporation under reduced pressure, compound III was obtained.

[0054] 1 H NMR (500 MHz, CDCl 3 ) : δ 7.39 (d, J = 4.9 Hz, 1H), 7.20 (d, J = 7.7 Hz, 1H), 7.14 (d, J = 7.1 Hz, 1H), 7.07 (d, J = 4.9 Hz, 1H), 6.95 (dd, J = 16.2, 7.4 Hz, 2H), 0.37 (s, 18H).

[0055] 13 C NMR (125 MHz, CDCl 3 ) : δ 143.94, 143.42, 143.17, 140.46, 136.72, 135.59, 134.30, 133.59, 131.32, 129.19, 127.42, 126.72.

[0056] (TOF - ESI+) (m / z) : C 18 H 24 S 3 Si 2 392.74.

[0057] II. Synthesis of compound V , and the process is described as follows:

[0058] Under a nitrogen atmosphere and at a temperature of -78 °C, 15 mL of a THF solution of n-BuLi (20 mmol) was added dropwise to a 50 mL THF solution of compound III (20 mmol). The mixture was stirred at this temperature for 0.5 h, and then 15 mL of a THF solution of compound IV (25 mmol) was added dropwise. After that, the mixture was continuously stirred at -78 °C for 1 h, and then the reaction system was slowly warmed to room temperature and stirred overnight. The reaction was quenched with saturated NH 4 Cl solution (50 mL). The reaction solution was extracted 3 times with ether (150 mL). The organic layers were combined, washed with saturated brine, dried over anhydrous sodium sulfate for 30 minutes, filtered to remove sodium sulfate, and the organic solvent was removed by rotary evaporation to obtain a solid. The solid was washed with methanol and filtered, and after drying, compound V was obtained.

[0059] 1 1H NMR (500 MHz, CDCl3): δ 7.35 (s, 1H), 7.26 (d, J = 7.7 Hz, 1H), 7.19 (d, J = 7.1 Hz, 1H), 6.96 (d, J = 7.7 Hz, 1H), 6.91 (d, J = 7.1 Hz, 1H), 1.23 (s, 12H), 0.37 (s, 18H).

[0060] 13 13C NMR (125 MHz, CDCl 3 ) : δ 144.19, 143.46, 142.79, 140.74, 140.17, 134.79, 134.67, 134.26, 133.58, 131.65, 130.17, 127.20, 83.78, 24.83.

[0061] (TOF-ESI+) (m / z): C 24 H 35 BO 2 S 3 Si 2 518.70.

[0062] III. Synthesis of compound VI , and the process is described as follows:

[0063] Under a nitrogen atmosphere, 12 mL of a THF solution of iodine monochloride (20 mmol) was added to 20 mL of a THF solution of compound III (4 mmol). After stirring at room temperature for 1 h, the reaction mixture was added to a sodium bicarbonate solution (50 mL), stirred evenly, and 10% sodium sulfite solution was added dropwise until the solution decolorized to remove excess ICl. The reaction solution was extracted 3 times with 50 mL of diethyl ether. The organic layers were combined, washed with saturated brine, dried over anhydrous sodium sulfate for 30 minutes, filtered to remove sodium sulfate, and the organic solvent was removed by rotary evaporation to obtain a crude product. The crude product was purified by silica gel column chromatography and dried to obtain compound VI.

[0064] 1 H NMR (500 MHz, CDCl 3 ) : δ 7.45 (d, J = 4.8 Hz, 1H), 7.31 - 7.25 (m,1H), 7.09 (d, J = 4.9 Hz, 1H), 6.70 (dd, J = 12.9, 6.1 Hz, 2H).

[0065] 13 C NMR (125 MHz, CDCl3) : δ 141.24, 140.00, 138.31, 137.37, 134.47, 131.91, 130.07, 128.55, 127.90, 126.07, 74.90, 74.79.

[0066] (TOF-ESI+) (m / z) : C 12 H 6 I 2 S 3 500.17.

[0067] IV. Synthesis of compound VII , and the process is described as follows:

[0068] Under a nitrogen atmosphere, compound V (20 mmol), compound VI (10 mmol), K 2 CO 3 (20 mmol), Pd(PPh 3 ) 4(0.2 mmol), a mixed solution of toluene and water (volume ratio of toluene to water is 5:1, 110 mL) was added via a syringe, heated to 110 °C, refluxed for 30 h. After cooling to room temperature, the reaction solution was poured into water and extracted three times with dichloromethane (50 mL). The organic layers were combined, dried over anhydrous sodium sulfate, and further dried over anhydrous sodium sulfate for 30 minutes. Sodium sulfate was removed by filtration, and the organic solvent was removed by rotary evaporation to obtain the crude product. The crude product was purified by silica gel column chromatography and dried to obtain Compound VII.

[0069] 1 H NMR (500 MHz, CDCl 3 ) : δ 7.68 (d, J = 4.8 Hz, 1H), 7.26 - 7.21 (m,1H), 7.19 -7.12 (m, 1H), 6.99 - 6.90 (m, 2H), 0.37 (s, 9H).

[0070] 13 C NMR (125 MHz, CDCl 3 ) : δ 143.98, 143.46, 140.89, 140.34, 140.32,139.93, 139.90, 138.01, 137.33, 137.01, 134.43, 134.37, 134.32, 134.28,133.94, 133.90, 133.88, 133.62, 133.58, 131.34, 129.50, 129.49, 127.94,127.84, 126.74, 126.69, 126.68, 126.50, 126.46, 125.51, 125.42.

[0071] (TOF - ESI+) (m / z) : C 48 H 52 S 9 Si 4 1029.82.

[0072] V. Synthesis of Compound VIII , the process is described as follows:

[0073] Under a nitrogen atmosphere at -78 °C, 10 mL of a THF solution of n-BuLi (10 mmol) was added dropwise to a 25 mL THF solution of compound VII (10 mmol). The mixture was stirred at -78 °C for 0.5 h, and then 10 mL of a THF solution of compound IV (12.5 mmol) was added dropwise. After stirring at -78 °C for 1 h, the reaction system was slowly warmed to room temperature and stirred overnight. The reaction was quenched with saturated NH 4 Cl solution (50 mL). The reaction mixture was extracted three times with ether (50 mL). The organic layers were combined, washed with saturated brine, and dried over anhydrous sodium sulfate for 30 minutes. The sodium sulfate was removed by filtration, and the organic solvent was removed by rotary evaporation to obtain a solid. The solid was washed with methanol and filtered to obtain compound VIII.

[0074] 1 H NMR (500 MHz, CDCl 3 ) : δ 7.68 (d, J = 4.8 Hz, 3H), 7.55 (s, 1H), 7.33 (d, J = 6.2 Hz, 1H), 7.26 - 7.20 (m, 4H), 6.99 - 6.90 (m, 6H), 1.23 (s, 12H), 0.37 (s, 36H).

[0075] 13 C NMR (125 MHz, CDCl 3 ) : δ 143.98, 143.46, 140.47, 140.34, 140.32, 140.12, 139.93, 139.91, 138.46, 137.37, 137.03, 134.35, 134.33, 134.32, 134.28, 133.94, 133.90, 133.62, 133.58, 132.92, 132.52, 132.21, 129.50, 129.49, 128.80, 126.72, 126.69, 126.68, 126.50, 126.46, 126.11, 125.40, 83.78, 24.83.

[0076] (TOF-ESI+) (m / z) : C 54 H 63 BO 2 S 9 Si 4 1155.79.

[0077] VI. Synthesis of compound X , and the process is described as follows:

[0078] Under a nitrogen atmosphere, compound IX (10 mmol), iodine (0.5 mmol) and sulfuric acid (98%, 45 ml) were added to a three-necked flask, and the mixture was stirred at room temperature for 2 h to obtain a mixed solution. The temperature was raised to 80 °C, and bromine (30 mmol) was added dropwise within 1 h. The reaction was carried out at 80 °C for 16 h. Subsequently, after cooling to room temperature, the reaction solution was slowly poured into ice water (3 L) to obtain a precipitate. The crude product was obtained by filtration and further separated by column chromatography to obtain compound X.

[0079] 1 H NMR (500 MHz, CDCl 3 ) : δ 8.68 (s, 1H), 8.50 (d, J = 8.2 Hz, 1H), 8.01 (dd, J = 23.5, 8.3 Hz, 1H).

[0080] 13 C NMR (125 MHz, CDC l3 ) : δ 164.68, 163.85, 134.05, 133.23, 130.72, 130.71, 130.59, 129.51, 129.27, 125.38, 125.23, 121.78, 121.42, 118.12.

[0081] (TOF-ESI+) (m / z) C 24 H 6 Br 2 O 6 550.11.

[0082] VII. Synthesis of compound XII , and the route is as follows:

[0083] Under a nitrogen atmosphere, imidazole (15 g) was heated to 90 °C. After compound X (2 mmol) was dissolved, compound XI (4.4 mmol) was added. After mixing evenly, the temperature was raised to 180 °C, and the reaction was stirred for 4 h. Then, it was cooled to room temperature, and water (10 mL) was added to quench the reaction. Subsequently, HCl (1 mL) was added for acidification. Stirring was continued for 12 h, and the solid was obtained by filtration. The solid was washed with distilled water until neutral to obtain the crude product, which was further purified by column chromatography to obtain compound XII.

[0084] 1 H NMR (500 MHz, CDCl 3) : δ 8.63 (d, J = 8.6 Hz, 1H), 8.26 (s, 1H), 8.06 (dd, J = 12.8, 8.6 Hz, 1H), 7.44 - 7.38 (m, 2H), 7.02 (dt, J = 8.5, 1.0 Hz, 2H), 5.20 (t, J = 4.9 Hz, 1H), 3.17 (td, J = 5.6, 4.8 Hz, 2H), 2.62 (tt, J = 7.8, 1.0 Hz, 2H), 1.82 (tt, J = 7.9, 5.8 Hz, 2H).

[0085] 13 C NMR (125 MHz, CDCl 3 ) : δ 164.41, 163.46, 156.39, 134.98, 134.54, 133.36, 131.48, 131.38, 130.38, 130.23, 129.38, 128.93, 128.28, 128.10, 126.64, 123.88, 123.83, 122.71, 118.30, 79.54, 40.36, 32.72, 29.99, 28.30.

[0086] (TOF - ESI+) (m / z) C 52 H 46 Br 2 N 4 O 8 1014.77.

[0087] IX. Synthesis of Compound XIII , the route is as follows:

[0088] Under a nitrogen atmosphere, add Compound VIII (2 mmol), Compound XII (1 mmol), K 2 CO 3 (2 mmol), Pd(PPh 3 ) 4 (0.02 mmol) to a two - necked flask. Add a mixture of toluene and water (volume ratio of toluene to water is 5:1) (11 mL) via a syringe, heat to 110 °C, and reflux for 30 h. After cooling to room temperature, pour the reaction mixture into water and extract three times with dichloromethane (15 mL). Dry the organic layer with anhydrous sodium sulfate and remove the solvent. Purify the obtained crude product by silica gel column chromatography to obtain Compound XIII.

[0089] 1 H NMR (500 MHz, CDCl 3 ) : δ 1 H NMR (500 MHz, Chloroform-d) δ 8.62 (d, J = 8.6 Hz, 2H), 8.01 (d, J = 8.6 Hz, 2H), 7.68 (d, J = 4.8 Hz, 3H), 7.44 - 7.38 (m, 3H), 7.30 - 7.22 (m, 3H), 7.20 - 7.14 (m, 3H), 7.09 - 6.98 (m, 6H), 6.94 (dd, J = 15.9, 7.4 Hz, 6H), 5.20 (t, J = 4.9 Hz, 3H), 3.17 (td, J = 5.6, 4.8 Hz, 3H), 2.62 (tt, J = 7.7, 1.0 Hz, 3H), 1.82 (tt, J = 7.9, 5.8 Hz, 3H), 0.37 (s, 36H).

[0090] 13 C NMR (125 MHz, CDCl 3 ) δ 166.82, 165.14, 156.50, 143.98, 143.46, 140.92, 139.59, 139.05, 138.73, 138.63, 138.36, 137.28, 135.02, 134.11, 134.01, 134.00, 133.94, 133.64, 133.52, 132.32, 132.24, 131.48, 129.58, 129.53, 129.50, 129.38, 128.59, 128.42, 128.38, 128.28, 127.77, 127.60, 127.50, 127.35, 127.27, 126.98, 126.86, 126.45, 126.07, 125.52, 124.95, 124.37, 122.19, 120.71, 79.55, 40.22, 32.69, 29.66, 28.30.

[0091] (TOF-ESI+) (m / z) : C 148 H 148 N 4 O 8 S 18 Si8 2912.59。

[0092] X. Removal of the protecting group of Compound XIII to obtain a polythienyl dendritic compound of a perylene diimide core , and the process is as follows:

[0093] Under a nitrogen atmosphere, Compound XIII (5 mmol) and a dichloromethane solution (20 mL) of 50% trifluoroacetic acid were added to a two-necked flask. After stirring at room temperature for 2 h, saturated sodium bicarbonate solution was added, and extraction was carried out, followed by repeated washing until neutral. The organic layer was collected and the solvent was removed by rotary evaporation to obtain a polythienyl dendritic compound of a perylene diimide core.

[0094] 1 H NMR (500 MHz, CDCl 3 ) : δ 7.60 -7.53 (m, 1H), 7.48 (dd, J = 5.1, 1.7Hz, 1H), 7.44 - 7.38 (m, 1H), 7.35 - 7.25 (m, 4H), 7.18 (d, J = 5.9 Hz, 1H),7.11 (dd, J = 6.1, 5.0 Hz, 1H), 7.09 - 7.00 (m, 2H), 7.03 - 6.98 (m, 1H),2.77 (tt, J = 6.3, 5.4 Hz, 1H), 2.64 (tt, J = 7.5, 1.0 Hz, 1H), 1.83 (tt, J =7.6, 5.3 Hz, 1H).

[0095] 13 C NMR (125 MHz, CDCl 3) : δ 166.82, 165.14, 140.92, 139.05, 138.79, 138.78, 138.36, 137.53, 137.28, 134.27, 134.23, 133.52, 133.35, 132.32, 132.24, 131.70, 129.58, 129.50, 129.38, 128.79, 128.60, 128.43, 128.42, 128.38, 128.28, 128.05, 127.77, 127.60, 127.50, 127.35, 127.27, 126.98, 126.86, 126.45, 125.79, 125.66, 125.01, 124.95, 124.37, 122.19, 120.71, 41.70, 33.06, 33.01。

[0096] (TOF-ESI+) (m / z) C 114 H 68 N 4 O 4 S 18 2134.90。

[0097] Example 2

[0098] To prepare a single-molecule device for a two-color light source based on femtosecond two-photon absorption, the following steps are included:

[0099] S100. Prepare a graphene array electrode on a substrate;

[0100] S200. Construct a graphene source electrode and a graphene drain electrode on the graphene array electrode;

[0101] S300. Immerse the graphene source electrode and the graphene drain electrode in a pyridine solution of a perylene diimide core multi-thiophene-based dendritic compound containing a condensing agent, so that the single-molecule perylene diimide core multi-thiophene-based dendritic molecules self-assemble between the graphene source electrode and the graphene drain electrode to obtain a single-molecule device for a two-color light source based on femtosecond two-photon absorption.

[0102] The specific process of step S100 is as follows:

[0103] Ultrasonically clean the copper foil with acetone and isopropanol for 10 minutes each in sequence, then soak it in 5% dilute hydrochloric acid for 5 minutes to remove the oxide layer, and finally rinse it with deionized water and dry it with nitrogen. Put the dried copper foil into a chemical vapor deposition reaction chamber, heat it to 1000 °C, and introduce H 2(Flow rate 200 sccm) and Ar (flow rate 200 sccm), annealing time 60 minutes; methane is introduced as the carbon source, flow rate 20 sccm, hydrogen flow rate 200 sccm, maintain at 1000 °C for 20 minutes, turn off heating, and cool down to room temperature at a rate of 50 °C / min in H 2 / Ar atmosphere to obtain monolayer graphene;

[0104] The above monolayer graphene is pasted onto a clean quartz wafer with transparent tape, and polymethyl methacrylate (PMMA) is spin-coated on the monolayer graphene. Spin-coat for 40 seconds at 4000 revolutions per minute using a spin coater, bake the glue on a heating stage at 180 °C for 2 min, etch the excess PMMA and graphene on the back of the copper foil through oxygen plasma to obtain a PMMA-monolayer graphene-copper foil structure. Cut it into 1 cm × 1 cm small pieces, place them in a 1M ferric chloride solution to dissolve the copper foil on the back, soak in 0.1 M HCl for 10 minutes to remove metal ions, and then rinse 3 times with deionized water to obtain a PMMA-supported monolayer graphene film. Transfer this film to a silicon wafer covered with 300 nm silicon oxide, soak in 1% HCl for 5 minutes in sequence, rinse with deionized water, soak in 0.01 M KOH for 2 minutes, rinse with deionized water, then let it stand, dry, and remove the glue to obtain a graphene-silicon wafer layer;

[0105] Photoresist is spin-coated on the graphene surface (3000 rpm × 40 s), pre-baked at 180 °C for 1 minute, use a strip mask, and successively undergo ultraviolet exposure at 80 mJ / cm², development with methyl isobutyl ketone diluted with isopropyl alcohol (volume ratio of methyl isobutyl ketone to isopropyl alcohol is 1:3), and fixing with isopropyl alcohol to obtain graphene dot electrodes.

[0106] The graphene dot electrodes are subjected to oxygen plasma etching and electro-burning to remove the exposed graphene. Use a probe station and a source meter to test the on-off of each pair of electrodes to obtain a graphene nano-gap dot electrode array.

[0107] The graphene nano-gap dot array electrodes include graphene source end electrodes and graphene drain end electrodes. Test the conductivity of the graphene array electrodes at a voltage of 50 mV, and screen out the substrates with conductivity in the order of 10 μA for subsequent steps.

[0108] The specific process of S300 is as follows:

[0109] Place the graphene nano-gap point array electrodes screened above in a two-neck flask. Add 5 ml of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 5 ml of a pyridine solution of a polythienyl dendritic compound with a perylene diimide core at a concentration of 0.5 mM to the two-neck flask. React for 48 h in a nitrogen atmosphere to make the -NH at both ends of the polythienyl dendritic compound with a perylene diimide core 2 form an amide covalent bond with the -COOH at the end of the graphene nano-gap point electrode. Wash three times with deionized water and acetone, and dry with nitrogen to obtain a single-molecule device of a two-color light source based on femtosecond two-photon absorption.

[0110] Use stochastic optical reconstruction microscopy to detect the emission spectrum of the single-molecule device of the two-color light source based on femtosecond two-photon absorption. The process is as follows:

[0111] The femtosecond laser is split by a semi-transmissive semi-reflective mirror and then modulated into an optical pulse with a specific wavelength by an optical parametric amplifier. The time delay of the two optical pulses reaching the molecular device is controlled by a pulse delay system. The two optical pulses are focused on the single-molecule device of the two-color light source based on femtosecond two-photon absorption through a coupling lens. Generally speaking, the pulse wavelength is matched with the energy level of the molecule, and the pulse delay system is adjusted. When the time delay of the optical pulse reaching the molecular device reaches the femtosecond order of magnitude, two-photon absorption of the two-color light source constructed by the polythienyl dendritic molecule based on the perylene diimide core can be triggered, enabling the molecule to absorb photons and transition to a higher energy level, realizing transition luminescence.

[0112] When the bias voltage is 2 V, by modulating the corresponding wavelength of the femtosecond laser to 1160 nm (the corresponding photon energy is 1.07 eV) and controlling the delay of the two beams of light above picoseconds with a time delay device, the molecular emission spectrum of the single-molecule device of the two-color light source based on femtosecond two-photon absorption provided in this embodiment is as Figure 2 shown, and the molecular emission peak is around 450 nm.

[0113] When the bias voltage is 2 V, by modulating the corresponding wavelength of the femtosecond laser to 1630 nm (the corresponding photon energy is 0.76 eV) and controlling the delay of the two beams of light at the femtosecond order of magnitude with a time delay device, the molecular emission spectrum of the single-molecule device of the two-color light source based on femtosecond two-photon absorption provided in this embodiment is as Figure 3 shown, and the molecular emission peak is around 300 nm.

[0114] Under the condition of a constant bias voltage, the spectrum of the single-molecule device of the two-color light source based on femtosecond two-photon absorption provided by the present invention changes with the wavelength of the femtosecond light modulation and the optical path time delay, and reflects the conversion of the polythienyl dendritic molecule with a perylene diimide core between single-photon and two-photon absorption, realizing the light-emitting function of the two-color light-emitting diode, Figure 2 and Figure 3The results show that the polythienyl dendritic molecules with perylene diimide core are successfully connected between the graphene nanogap point electrodes, and the performance of the single-molecule device of the two-color light source based on femtosecond two-photon absorption provided by the present invention can be relatedly regulated by the bias voltage and the modulation of optical parameters.

[0115] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements 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 two-color light source single-molecule device based on femtosecond two-photon absorption, characterized in that: include: A substrate, a graphene source electrode, and a graphene drain electrode, wherein the graphene source electrode and the graphene drain electrode form a graphene electrode pair, and the graphene electrode pair is arranged on the top layer of the substrate; A two-color light source, wherein the two-color light source uses a single-molecule perylene imide core polythiophene branched molecule as a light-emitting molecule, and the two -NH2 ends of the polythiophene branched molecule of the perylene imide core are respectively connected to the graphene source terminal electrode and the graphene drain terminal electrode through amide bonds; The structural formula of the polythienyl branched molecule with perylene imide core is as follows: 。 2. The dual-color light source single-molecule device based on femtosecond two-photon absorption as claimed in claim 1, characterized in that: The graphene source terminal electrode and the graphene drain terminal electrode are nano-gap point electrodes.

3. The dual-color light source single-molecule device based on femtosecond two-photon absorption as claimed in claim 1, characterized in that: It also includes a packaging layer, which covers the graphene electrode pair and the two-color light source.

4. The dual-color light source single-molecule device based on femtosecond two-photon absorption as claimed in claim 3, characterized in that: The encapsulation layer is selected from hexagonal boron nitride materials.

5. The dual-color light source single-molecule device based on femtosecond two-photon absorption as claimed in claim 1, characterized in that: The material of the substrate is selected from silicon wafer.

6. A method for preparing a dual-color light source single-molecule device based on femtosecond two-photon absorption, characterized in that: The method for preparing a dual-color light source single-molecule device based on femtosecond two-photon absorption as claimed in any one of claims 1 to 5 comprises the following steps: S100, preparing a graphene array electrode on a substrate; S200, constructing a graphene source electrode and a graphene drain electrode on the graphene array electrode; S300, immersing the graphene source electrode and the graphene drain electrode in a pyridine solution of a polythiophene-based branched compound with a perylene imide core containing a condensation agent, so that single-molecule polythiophene-based branched molecules with a perylene imide core are self-assembled between the graphene source electrode and the graphene drain electrode, thereby obtaining a dual-color light source single-molecule device based on femtosecond two-photon absorption.

7. The method for preparing a dual-color light source single-molecule device based on femtosecond two-photon absorption according to claim 6, characterized in that: In step S300, the concentration of the pyridine solution of the polythienyl dendron compound with a perylene imide core is not less than 0.25 mM.

8. The method for preparing a dual-color light source single-molecule device based on femtosecond two-photon absorption according to claim 6, characterized in that: In step S300, the condensation agent is selected from 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride.

9. The method for preparing a dual-color light source single-molecule device based on femtosecond two-photon absorption according to claim 6, characterized in that: The emission spectrum of the two-color light source single-molecule device based on femtosecond two-photon absorption obtained in step S300 is detected using random optical reconstruction microscopy.

10. The method for preparing a dual-color light source single-molecule device based on femtosecond two-photon absorption according to claim 9, characterized in that: The femtosecond excitation photons of the dual-color light source single-molecule device based on femtosecond two-photon absorption are located in the wavelength range of 1160 to 1630 nm, and the molecular emission peak is located in the wavelength range of 200 nm to 450 nm.

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