Single-molecule electroluminescent device based on light-emitting free radicals and preparation method of single-molecule electroluminescent device

Abstract

The invention relates to the technical field of electroluminescent devices, in particular to a monomolecular electroluminescent device based on light-emitting free radicals and a preparation method thereof.The monomolecular electroluminescent device based on the light-emitting free radicals comprises an electroluminescent unit, a graphene point source terminal electrode and a graphene point drain terminal electrode, the left end and the right end of the electroluminescent unit are respectively connected with the graphene point source terminal electrode and the graphene point drain terminal electrode through amido bonds or ester bonds to form the monomolecular luminescent free radical molecule field effect transistor, and a single luminescent free radical molecule is selected as the electroluminescent unit, so that the luminescent center of the molecular level can be accurately controlled; electroluminescence with high efficiency, high stability and long service life can be realized, and luminescent free radical molecules have the characteristic of efficient luminescence from the lowest bilinear state to the ground state; according to the preparation method provided by the invention, the preparation process is simple, the conditions are easy to control, and the development of the technical fields of electroluminescence and emerging quantum is facilitated.

Description

Technical Field

[0001] The invention relates to the technical field of electroluminescent devices, and in particular to a single-molecule electroluminescent device based on luminescent free radicals and a preparation method thereof. Background Art

[0002] Electroluminescence is a phenomenon in which a material emits photons by applying an electric field. Its basic principle is that under the action of an external electric field, electrons and holes are injected into the material from the cathode and anode respectively. These carriers migrate in the material and eventually recombine in the light-emitting layer, releasing energy and emitting it in the form of photons. Electroluminescent devices are display devices that use electroluminescent materials to emit light when stimulated.

[0003] Although traditional light-emitting devices have advantages such as self-luminescence and wide color gamut, they have limitations in terms of luminous efficiency, stability and service life. Summary of the invention

[0004] 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 electroluminescent device based on luminescent free radicals; the second object of the present invention is to provide a method for preparing a luminescent device.

[0005] In order to achieve the first purpose, the technical solution adopted by the present invention is: A single-molecule electroluminescent device based on luminescent free radicals comprises an electroluminescent unit, a graphene point source terminal electrode and a graphene point drain terminal electrode, wherein the left end and the right end of the electroluminescent unit are respectively connected to the graphene point source terminal electrode and the graphene point drain terminal electrode through an amide bond or an ester bond to form a single-molecule luminescent free radical molecular field effect tube; The electroluminescent unit is composed of a single molecule of luminescent free radical molecules, and the structural formula of the luminescent free radical molecules is as follows: or ; Among them, R1 is , , , and Any one of the above, R2 is OH or NH2.

[0006] Furthermore, the graphene point source terminal electrode and the graphene point drain terminal electrode are both graphene nanogap point electrodes.

[0007] Furthermore, the graphene point source terminal electrode and the graphene point drain terminal electrode are both graphene array electrodes.

[0008] Furthermore, the graphene point source terminal electrode and the graphene point drain terminal electrode are arranged on the hafnium oxide dielectric layer.

[0009] Furthermore, the single-molecule light-emitting free radical molecular field effect tube is encapsulated by polydimethylsiloxane.

[0010] In order to achieve the second purpose, the technical solution adopted by the present invention is: A method for preparing a light-emitting device, for preparing a single-molecule electroluminescent device based on light-emitting free radicals as described in any one of the above, comprising the preparation of a single-molecule light-emitting free radical molecular field effect tube, the steps of which are as follows: S100, preparing a graphene point source terminal electrode and a graphene point drain terminal electrode; S200, connecting the left and right ends of the luminescent free radical molecule to the graphene point source terminal electrode and the graphene point drain terminal electrode through an amide bond or an ester bond, respectively, to obtain a single molecule luminescent free radical molecular field effect tube.

[0011] Furthermore, the preparation process of step S200 is as follows: under the protection of inert gas, a graphene point source terminal electrode, a graphene point drain terminal electrode, a carbonyl activation reagent, a luminescent free radical molecule and anhydrous pyridine are added to a reaction container, reacted for 36 to 54 hours, taken out, rinsed, and blown dry to obtain a single-molecule luminescent free radical molecular field effect transistor.

[0012] Furthermore, the carbonyl activation reagent is 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride.

[0013] Furthermore, the concentration of the luminescent free radical molecules is 0.5×10 −4 ~1.5×10 −4 mol / L.

[0014] Furthermore, the method further comprises step S300, wherein the process is as follows: the single-molecule light-emitting free radical molecular field effect transistor in step S200 is packaged to obtain a single-molecule electroluminescent device based on light-emitting free radicals.

[0015] The above one or more technical solutions in the embodiments of the present invention have at least one of the following technical effects: The present invention provides a single-molecule electroluminescent device based on luminescent free radicals. A single luminescent free radical molecule is selected as a functional molecule, and the luminescent center at the molecular level can be precisely controlled to achieve high-efficiency, high-stability and long-life electroluminescence. The luminescent free radical molecule has the characteristics of efficient luminescence from the lowest doublet state to the ground state.

[0016] The present invention provides a method for preparing a light-emitting device, which has a simple preparation process and easily controllable conditions, can achieve wavelength-controllable, high-purity, and high-efficiency single photon generation, and is helpful to promote the development of electroluminescence and emerging quantum technology fields.

[0017] 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

[0018] Figure 1 It is a schematic structural diagram of a single-molecule electroluminescent device based on luminescent free radicals provided in Example 3 of the present invention.

[0019] Figure 2 This is the test result of the electrical characteristics of the single-molecule light-emitting free radical molecular field effect tube provided in Example 3 of the present invention.

[0020] Figure 3 This is the detection result of the luminescent point of a single-molecule electroluminescent device based on luminescent free radicals provided in Example 3 of the present invention.

[0021] Reference numerals 1. Gate; 2. Dielectric layer; 31. Electroluminescent unit; 32. Graphene point source terminal electrode; 33. Graphene point drain terminal electrode. DETAILED DESCRIPTION

[0022] 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.

[0023] In the following examples, the experimental methods used are conventional methods unless otherwise specified, and the materials, reagents, etc. used are all available from commercial sources unless otherwise specified.

[0024] According to a specific embodiment provided by the present invention, a single-molecule electroluminescent device based on luminescent free radicals, such as Figure 1 As shown, it includes a gate 1, a dielectric layer 2 and a single molecule light-emitting free radical molecular field effect tube (not shown in the figure) arranged in sequence in a longitudinal direction; The single-molecule light-emitting free radical molecular field effect tube comprises an electroluminescent unit 31, a graphene point source terminal electrode 32 and a graphene point drain terminal electrode 33, and the left end and the right end of the electroluminescent unit 31 are respectively connected to the graphene point source terminal electrode 32 and the graphene point drain terminal electrode 33 through an amide bond or an ester bond to form a single-molecule light-emitting free radical molecular field effect tube; The electroluminescent unit is composed of a single molecule of luminescent free radical molecules, and the structural formula of the luminescent free radical molecules is as follows: or ; Among them, R1 is , , , and Any one of, R2 is OH or NH2; The luminescent free radical molecule can be prepared by any of the following routes: or .

[0025] Example 1 preparation , the process is as follows: Under nitrogen atmosphere and protected from light, (0.5 mmol), (0.54mmol), Pd(PPh3)4 (0.04mmol), toluene (10mL), K3PO4 aqueous solution (6mL) and ethanol (4mL) were added to a two-necked flask. After stirring at 90℃ for 48h, the reaction mixture was cooled to room temperature and 5% hydrochloric acid was gradually added until no bubbles were generated. Then, it was extracted with dichloromethane, and the organic phase was separated and dried with MgSO4. Finally, the crude product was purified by silica gel column chromatography (using petroleum ether and dichloromethane in a volume ratio of 3:1 as eluent) to obtain .

[0026] Under nitrogen atmosphere, (0.2 mmol), (0.44 mmol), Pd(PPh3)4 (0.015 mmol), CuI (0.03 mmol), triethylamine (4 mL) and tetrahydrofuran (30 mL) were added to a two-necked flask, and then the reaction was continuously stirred at 90 °C for 12 h. The mixture was cooled to room temperature and extracted with dichloromethane. The organic phase was collected and dried over Na2SO4. The crude product was further purified by silica gel column chromatography (using petroleum ether and ethyl acetate in a volume ratio of 3:1 as the eluent) to obtain ; 1 H NMR (500 MHz, chloroform- d ): δ 8.09 (dd, J = 7.3, 1.6 Hz, 1H), 7.97 – 7.92(m, 1H), 7.92 – 7.88 (m, 1H), 7.88 – 7.81 (m, 3H), 7.61 (dd, J = 7.4, 1.7 Hz,1H), 7.55 – 7.47 (m, 6H), 7.38 (d, J = 1.6 Hz, 1H), 7.36 (s, 4H), 7.31 – 7.25 (m, 1H), 7.25 – 7.19 (m, 1H), 5.36 (s, 1H), 2.89 – 2.73 (m, 4H), 2.50 (t, J =6.2 Hz, 4H), 2.47 – 2.35 (m, 4H), 1.79 – 1.60 (m, 4H); HRMS (ESI + ) m / z: [M] + C 51 H 37 The calculated value of Cl6N3 is 901.1113; the actual value is 901.1105.

[0027] Under nitrogen atmosphere and protected from light, (0.1 mmol), 40% tetrabutylammonium hydroxide aqueous solution (0.26 mmol) and tetrahydrofuran (30 mL) were added into a two-necked flask. After stirring at room temperature for 12 h, tetrachlorobenzoquinone (0.28 mmol) was added into the reaction system. After stirring for 1 h, the reaction was continued by triethylamine pretreated silica gel column chromatography (using petroleum ether and ethyl acetate in a volume ratio of 3:1 as eluent) to purify the crude product. ; HRMS (ESI +) m / z: [M] + C 51 H 36 The calculated value of Cl6N3 is 900.1035 and the actual value is 900.1022.

[0028] Example 2 preparation , the process is as follows: In a nitrogen atmosphere and protected from light, add (0.5 mmol), (0.54 mmol), Pd(PPh3)4 (0.04 mmol), toluene (9 mL), K2CO3 aqueous solution (6 mL) and ethanol (4 mL) were stirred at 90 °C for 48 h; after the reaction was completed, the reaction mixture was cooled to room temperature, and 5% hydrochloric acid was gradually added until no bubbles were generated, and then extracted with dichloromethane, and the organic phase was separated and dried with MgSO4. Finally, the crude product was purified by silica gel column chromatography (using petroleum ether and dichloromethane in a volume ratio of 3:1 as eluent) to obtain .

[0029] Under nitrogen atmosphere, (0.2 mmol), (0.44 mmol), Pd(PPh3)4 (0.015 mmol), CuI (0.03 mmol), triethylamine (4 mL) and tetrahydrofuran (30 mL) were added to a two-necked flask, and then the reaction was stirred continuously at 90 °C for 12 h. The mixture was cooled to room temperature and extracted with dichloromethane. The organic phase was then collected and dried with Na2SO4. The crude product was further purified by silica gel column chromatography (using petroleum ether and ethyl acetate in a volume ratio of 10:1 as the eluent) to obtain ; 1 H NMR (500 MHz, chloroform- d ) δ 8.10 (s, 1H), 7.97 – 7.91 (m, 2H), 7.91 –7.81 (m, 3H), 7.65 – 7.58 (m, 2H), 7.56 – 7.45 (m, 3H), 7.38 (dd, J = 7.4, 1.5Hz, 1H), 7.25 (dtd, J = 24.9, 7.5, 1.7 Hz, 2H), 5.37 (s, 1H), 4.32 (t, J= 6.0Hz, 2H), 3.73 – 3.58 (m, 4H), 2.58 – 2.45 (m, 4H), 1.84 – 1.67 (m, 4H); HRMS (ESI + ) m / z: [M] + C 51 H 29 Cl 12 The calculated value of NO2 is 1106.8455 and the actual value is 1106.8467.

[0030] Under nitrogen atmosphere and protected from light, (0.1 mmol), 40% tetrabutylammonium hydroxide aqueous solution (0.26 mmol) and tetrahydrofuran (30 mL) were added to a two-necked flask. After stirring at room temperature for 12 h, tetrachlorobenzoquinone (0.28 mmol) was added to the reaction system. After stirring for 1 h, the crude product was purified by silica gel column chromatography pretreated with triethylamine (using petroleum ether and ethyl acetate in a volume ratio of 10:1 as the eluent) to obtain ; HRMS (ESI + ) m / z: [M] + C 51 H 28 Cl 12 The calculated value of NO2 is 1105.8377 and the actual value is 1105.8367.

[0031] Example 3 Preparation of a single-molecule electroluminescent device based on luminescent free radicals.

[0032] 1. Prepare the gate and dielectric layer.

[0033] The silicon wafer with 300 nm silicon oxide on the surface was cut into 1×1 cm 2 The square was placed in piranha washing solution (volume ratio of concentrated sulfuric acid and hydrogen peroxide is 7:3), heated to 110 °C on a hot plate for 4 h, ultrasonically cleaned with ultrapure water for 15 min, washed three times, and dried with nitrogen to obtain a clean silicon wafer, on which 8 nm of chromium and 60 nm of gold were thermally evaporated; According to the position of the evaporated chromium and gold, an ion beam sputtering system is used to coat a 30 nm thick aluminum film on the surface of the silicon wafer. Acetone is used to remove the glue, and the surface of the aluminum film is naturally oxidized to form a dense aluminum oxide as a dielectric layer. The metallic aluminum serves as the gate, which is connected to the chromium and gold evaporated on the surface of the silicon wafer.

[0034] In order to prevent leakage of optoelectronic devices, a 5 mm thick layer of hafnium oxide was prepared on the surface of the aluminum oxide dielectric layer by a sol-gel method to obtain a hafnium oxide dielectric layer. The process of preparing the hafnium oxide dielectric layer by the sol-gel method is as follows: a hafnium tetrachloride solution was prepared in a glove box, and the molar ratio of HfCl4, EtOH, HNO3 and H2O in the solution was 1:350:10:5. After the prepared hafnium tetrachloride was taken out, it was heated in an oil bath at 50°C for 3 h; it was spin-coated on the above-mentioned silicon wafer coated with aluminum film and maintained at a speed of 6000 rpm for 35 s; after standing for 1 h, it was treated with ultraviolet-ozone (UVO) for 1 h; then it was placed in a quartz reactor for ultraviolet (ultraviolet, UV) treatment for 3 h, and then slowly heated to 200°C in an atmospheric environment using a tube furnace and maintained for 1 h to obtain a hafnium oxide dielectric layer.

[0035] 2. Prepare single-molecule light-emitting free radical molecular field effect transistor.

[0036] (I) Prepare graphene point source terminal electrode and graphene point drain terminal electrode, the process is as follows: The cut copper sheet (2 cm wide, 5 cm long, 25 μm thick) was soaked in acetic acid for about 15 minutes, rinsed with ultrapure water and ethanol three times in sequence, and dried at 80 °C. The dried copper sheet was then placed in a chemical vapor deposition (CVD) tube furnace and evacuated with a mechanical pump until the vacuum degree was less than 1 Pa. Hydrogen was then passed through at a flow rate of 16 cm 3 ·min –1 , open the tube furnace and heat to 1030℃. Calculate the heating time from room temperature. After heating for 1 h, adjust the hydrogen flow rate to 8cm 3 ·min –1 , and at the same time, the carbon source (methane) flow rate was 1.6 cm 3 ·min –1 After 25 minutes of holding time, the tube furnace was closed and the temperature was naturally cooled. The hydrogen flow rate was adjusted back to 16 cm 3 ·min –1 , the methane flow rate was adjusted to 0.8 cm 3 ·min –1 When the temperature drops to 600 °C, turn off the carbon source, continue to drop the temperature to 200 °C, open the tube furnace lid to accelerate the temperature drop, drop the temperature to 100 °C, and take out the copper sheet on which the graphene has grown; Cut the copper sheet with graphene grown on it into 1×2 cm 2The copper pieces were glued to a clean quartz plate with transparent glue, and polymethyl methacrylate (950 PMMA) was spin-coated and heated at 180 °C for 2 minutes. The edges of the copper pieces and the areas glued with transparent glue were removed, and each copper piece was cut into two equal pieces (each piece was approximately 0.9 × 0.9 cm 2 ); Place the copper sheet with the back side facing up and the PMMA coated side facing down in a clean culture dish, and use oxygen plasma to etch the graphene grown on the back side of the copper sheet; Among them, during the spin coating of 950 PMMA on the coating machine, the spin coating was first performed at a speed of 600 rpm for 6 seconds, and then maintained at a speed of 4000 rpm for 40 seconds; During the process of oxygen plasma etching the graphene grown on the back of the copper sheet, the power was kept at 50 W and the etching time was 50 seconds; Place the etched copper sheet with the back side facing downward in a 2 M ferric chloride solution and soak until the copper sheet is completely corroded; use a clean silicon wafer to transfer the graphene to 10 mM, 5 mM, and 1 mM dilute hydrochloric acid solutions in sequence, and soak in each dilute hydrochloric acid solution for 30 minutes; then transfer to ultrapure water and let stand for 30 minutes; then wash and transfer the graphene to a 1 M strong potassium oxide solution and let stand for about 1.5 hours; then transfer to ultrapure water, ultrapure water, 1 mM dilute hydrochloric acid solution, ultrapure water, and ultrapure water in sequence, and let stand for 15 minutes each; then transfer the graphene to the above hafnium oxide dielectric layer and let stand until the surface water evaporates; then place it in hot acetone for 10 minutes to remove PMMA, blow dry with nitrogen to obtain a single layer of graphene; Photolithography of graphene strips with a width of 40 μm and a length of 200 μm, using oxygen plasma etching to etch away the exposed graphene, leaving the required graphene strips due to the protection of the photoresist, and dissolving the photoresist with acetone; Photolithography of electrodes, thermal evaporation of 8nm chromium and 60nm gold, and acetone debonding to obtain graphene array electrodes; There are 24 electrodes on each graphene strip, producing 23 channels for connecting molecules; and there are 9 graphene strips on a silicon wafer, with a total of 207 channels.

[0037] The surface of the graphene array electrode was heated at 180°C for 2 minutes, and 950 PMMA was spin-coated at a speed of 600 rpm for 6 seconds, and then kept at a speed of 4000 rpm for 40 seconds; an electron beam was used to etch a dotted line with a total length of 60 μm in the middle of each channel, each dotted line was 150 nm long and 5 nm wide, and the interval between the dotted lines was 40 nm; after electron beam etching, the graphene array electrode was immersed in a methyl isobutyl ketone solution diluted with isopropanol (volume ratio: methyl isobutyl ketone / isopropanol = 1 / 3) for development to obtain a graphene point electrode, which includes a graphene point source terminal electrode and a graphene point drain terminal electrode; The above-mentioned graphene point electrode is etched using oxygen plasma, and the graphene at both ends of the channel is interrupted; in the process of gradual etching, the current value at both ends of the channel is continuously tested to achieve a channel width at the nanometer level; after the etching is completed, PMMA is removed with acetone, and the other uninterrupted channels are burned off with Joule heat in the air to obtain a graphene nano-gap point electrode.

[0038] (ii) Connecting the left and right ends of the luminescent free radical molecule to the graphene point source electrode and the graphene point drain electrode respectively through an amide bond or an ester bond to obtain a single molecule luminescent free radical molecular field effect tube, the preparation process of which is as follows: In a nitrogen atmosphere, the graphene nanogap electrode and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (60×10 −4 M, 1 ml), the luminescent free radical molecules obtained in Example 1 (1×10 −4 M, 1ml) and anhydrous pyridine (10 mL) were added into a 50 mL double-necked bottle. After standing for 48 hours, it was taken out and rinsed with ultrapure water and acetone respectively, and dried with nitrogen. The left and right ends of the luminescent free radical molecule were connected to the graphene point source electrode and the graphene point drain electrode through amide bonds to form a single molecule luminescent free radical molecular field effect tube. The single molecule luminescent free radical molecular field effect tube was tested, and the results were as follows: Figure 2 As shown, the results show that under the condition of constant bias voltage, the molecular field effect transistor exhibits electrical characteristics that change with the gate voltage, indicating that the light-emitting free radical molecules have been successfully connected to the graphene nanogap point electrode and can be regulated by changing the gate voltage.

[0039] 3. Encapsulate the single-molecule light-emitting free radical molecular field effect tube. The process is as follows: The polydimethylsiloxane precursor and the crosslinking agent are fully mixed and spin-coated on the single-molecule light-emitting free radical molecular field effect tube prepared above, and the single-molecule electroluminescent device based on light-emitting free radicals is encapsulated to obtain a single-molecule electroluminescent device. The light-emitting point is detected, and the result is as follows: Figure 3 shown.

[0040] 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 electroluminescent device based on luminescent free radicals, characterized in that: It comprises an electroluminescent unit, a graphene point source terminal electrode and a graphene point drain terminal electrode, wherein the left end and the right end of the electroluminescent unit are respectively connected to the graphene point source terminal electrode and the graphene point drain terminal electrode through an amide bond or an ester bond to form a single molecule light-emitting free radical molecular field effect tube; The electroluminescent unit is composed of a single molecule of luminescent free radical molecules, and the structural formula of the luminescent free radical molecules is as follows: or ； Among them, R1 is , , , and Any one of the above, R2 is OH or NH2.

2. The single-molecule electroluminescent device based on luminescent free radicals according to claim 1, characterized in that: The graphene point source terminal electrode and the graphene point drain terminal electrode are both graphene nano-gap point electrodes.

3. The single-molecule electroluminescent device based on luminescent free radicals according to claim 1, characterized in that: The graphene point source terminal electrode and the graphene point drain terminal electrode are both graphene array electrodes.

4. The single-molecule electroluminescent device based on luminescent free radicals according to claim 1, characterized in that: The graphene point source terminal electrode and the graphene point drain terminal electrode are arranged on the hafnium oxide dielectric layer.

5. The single-molecule electroluminescent device based on luminescent free radicals according to claim 1, characterized in that: The single-molecule light-emitting free radical molecular field effect tube is encapsulated by polydimethylsiloxane.

6. A method for preparing a light emitting device, characterized in that: The steps for preparing a single-molecule electroluminescent device based on luminescent free radicals as claimed in any one of claims 1 to 5, including the preparation of a single-molecule luminescent free radical molecular field effect tube, are as follows: S100, preparing a graphene point source terminal electrode and a graphene point drain terminal electrode; S200, connecting the left and right ends of the luminescent free radical molecule to the graphene point source terminal electrode and the graphene point drain terminal electrode through an amide bond or an ester bond, respectively, to obtain a single molecule luminescent free radical molecular field effect tube.

7. The method for preparing a light emitting device according to claim 6, characterized in that: The preparation process of step S200 is as follows: under the protection of inert gas, a graphene point source terminal electrode, a graphene point drain terminal electrode, a carbonyl activation reagent, a luminescent free radical molecule and anhydrous pyridine are added to a reaction container, reacted for 36 to 54 hours, taken out, rinsed, and blown dry to obtain a single-molecule luminescent free radical molecular field effect tube.

8. The method for preparing a light emitting device according to claim 7, characterized in that: The carbonyl activation reagent is 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride.

9. The method for preparing a light emitting device according to claim 7, characterized in that: The concentration of the luminescent free radical molecules is 0.5×10 −4 ~1.5×10 −4 mol / L.

10. The method for preparing a light emitting device according to claim 6, characterized in that: The method further comprises a step S300, the process of which is as follows: encapsulating the single-molecule light-emitting free radical molecular field effect transistor in the step S200 to obtain a single-molecule electroluminescent device based on light-emitting free radicals.

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