Preparation method of light-operated thin film transistor based on PbS quantum dot / D-A TADF material three-dimensional heterojunction quantum well composite channel

Abstract

The invention relates to a preparation method of a light-operated thin film transistor based on a PbS quantum dot / D-A TADF material three-dimensional heterojunction quantum well composite channel, and the method comprises the steps: preparing a PbS quantum dot / D-A TADF material three-dimensional heterojunction quantum well composite film layer on a silicon / silicon dioxide substrate through employing a spin-coating film forming technology, and carrying out the preparation of a light-operated thin film transistor through employing the PbS quantum dot / D-A TADF material three-dimensional heterojunction quantum well composite channel; cr / Au composite metal electrodes are respectively formed on the PbS quantum dot / D-A TADF material three-dimensional heterojunction quantum well composite conductive channel layer through a graphical mask covering evaporation process technology, a corresponding source electrode and a corresponding drain electrode are led out, and effective packaging and protection of a quantum dot channel are realized through spin coating of organic matters. Therefore, the novel light-operated thin film transistor based on the PbS quantum dot / D-A TADF material three-dimensional heterojunction quantum well composite channel is prepared. The preparation method is novel, the manufacturing cost is low, the process is simple, meanwhile, the special photoelectric sensitivity characteristic of the PbS quantum dot / D-A TADF material three-dimensional heterojunction quantum well can be fully utilized, and then the sensitivity of the light-operated gate transistor is effectively improved.

Description

Technical Field

[0001] The present invention belongs to the field of semiconductor nanomaterials and devices, and particularly relates to a preparation method of a light-controlled thin-film transistor based on a three-dimensional heterojunction quantum well composite channel of PbS quantum dots / D-A TADF materials. Background Art

[0002] Thin-film transistors, as a very important type of semiconductor device, play a crucial role in fields such as information storage, transmission, and processing. However, up to now, the existing large-scale use of thin-film transistors is a semiconductor device based on microelectronic silicon technology. This traditional thin-film field-effect transistor based on silicon microelectronic technology has problems such as high requirements for equipment, complex preparation processes, high costs, limited overall device performance, limited sensitivity, switching frequency, and speed. Moreover, with the gradual increase in people's requirements for high-performance thin-film transistors, thin-film field-effect transistors based on microelectronic silicon technology are no longer able to meet the current information society's demand for thin-film field-effect transistors with high sensitivity, high switching frequency, and high switching speed.

[0003] In recent years, nanocrystal materials or quantum dot materials, due to their unique electrical and optical quantum size effects, provide another effective means for regulating material properties in addition to regulating chemical composition. Especially when semiconductor quantum dot colloids achieve effective overlap and coincidence of quantum-confined electron or hole wave functions through self-assembly and close packing, a new type of "artificial solid" will be formed. This artificial solid not only retains the unique tunability of quantum dot material properties, but also has relatively high carrier mobility and electrical conductivity. This provides the possibility for realizing the effective assembly of quantum dot colloids based on low-cost, large-area solution preparation technology, and thus preparing a new type of light-controlled thin-film transistor based on quantum dot conductive channels. In addition, a thin-film field-effect transistor based on a three-dimensional heterojunction quantum well composite channel formed by the combination of another organic semiconductor material with a large energy band difference and quantum dots can form a three-dimensional solid depletion layer and its three-dimensional quantum well structure between the three-dimensional heterojunction quantum well composite channels, thereby effectively regulating the carrier concentration and conductivity of this quantum dot / organic semiconductor composite material. Moreover, since quantum dots are sensitive to light irradiation, the carrier concentration of its conductive channel can be further regulated by light irradiation. Therefore, this provides a possibility and a new idea for the development of a preparation method of a light-controlled thin-film transistor based on a three-dimensional heterojunction quantum well composite channel of quantum dot / semiconductor materials. Summary of the Invention

[0004] The object of the present invention is to provide a preparation method of a light-controlled thin-film transistor based on a three-dimensional heterojunction quantum well composite channel of PbS quantum dots / D-ATADF materials, aiming at the deficiencies and defects of the existing technology. This method has low production cost and simple preparation process, and can make full use of the light field or electric field regulation effect of the three-dimensional heterojunction quantum well of PbS quantum dots / D-ATADF materials and the quantum size effect of the quantum dots themselves, so as to effectively improve the sensitivity of the light-controlled thin-film transistor with a three-dimensional heterojunction quantum well composite channel of PbS quantum dots / D-ATADF materials.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is: a preparation method of a light-controlled thin-film transistor based on a three-dimensional heterojunction quantum well composite channel of PbS quantum dots / D-ATADF materials, comprising the following steps: Step S1: Select a silicon / silicon dioxide substrate, and the silicon / silicon dioxide substrate includes a substrate silicon and a silicon dioxide film provided on the surface of the substrate silicon; Step S2: Prepare a PbS quantum dot solution and a D-ATADF material solution, and prepare a three-dimensional heterojunction quantum well composite film layer of PbS quantum dots / D-ATADF materials on the silicon / silicon dioxide substrate to be used as a conductive channel; Step S3: Prepare metal electrodes on the silicon / silicon dioxide substrate covered with the three-dimensional heterojunction quantum well composite film of PbS quantum dots / D-ATADF materials to obtain the source electrode and the drain electrode of the light-controlled thin-film transistor with a three-dimensional heterojunction quantum well composite structure of PbS quantum dots / D-ATADF materials; Step S4: Use organic encapsulation to prepare a thin-film transistor based on a light-controlled three-dimensional heterojunction quantum well composite conductive channel of PbS quantum dots / D-ATADF materials, and use light irradiation means to control the carrier concentration of the conductive channel.

[0006] Further, the specific method of step S2 includes the following steps: Step S21: Prepare a PbS quantum dot solution: Dissolve a set amount of lead oxide, oleic acid, and octadecene at a set temperature to prepare a lead precursor solution; Dissolve a set amount of sulfur powder in trioctylphosphine and inject it into a three-necked flask at a set speed, then quickly cool the quantum dot solution by means of a water bath, dilute it with n-hexane to obtain a quantum dot solution, and store it under low-temperature conditions; Take out a part of the supernatant of the quantum dot solution after standing, then add an appropriate amount of n-hexane solution and take out the upper layer solution, add absolute ethanol for centrifugation, and then dissolve the precipitate with n-hexane to obtain a purified quantum dot solution; Step S22: Prepare a D-ATADF material solution (using 9,9'- (dibenzo [f,h] quinoxaline - 6,11 - diyl) bis (N³,N³,N 6 ,N6 - (Tetraphenyl-9H-carbazole-3,6-diamine) (taking DQBC as an example): First, take a set amount of 2,7-dibromophenanthrene-9,10-dione and ethylenediamine, add them to an appropriate amount of acetic acid, and place them in a three-necked round-bottom flask. Under nitrogen protection, stir at a set temperature for a corresponding time. Cool to room temperature, dilute with an appropriate amount of water, and recrystallize the crude product with hot ethanol to obtain the white solid product 6,11-dibromodibenzo[f,h]quinoxaline; measure a set volume of toluene solution, and add the set amount of 6,11-dibromodibenzo[f,h]quinoxaline and N³,N³,N 6 ,N 6 - tetraphenyl-9H-carbazole-3,6-diamine, further add a set amount of sodium tert-butoxide, tris(dibenzylideneacetone)dipalladium, and 2-dicyclohexylphosphino-2,6′-dimethoxybiphenyl, and stir at a set temperature for a corresponding time under nitrogen protection. After the reaction is completed and cooled, extract the mixture with dichloromethane and wash with water. Dry the organic layer with magnesium sulfate and concentrate under reduced pressure. Purify the product by column chromatography to obtain the yellow solid, which is 9,9'-(dibenzo[f,h]quinoxaline-6,11-diyl)bis(N³,N³,N 6 ,N 6 - tetraphenyl-9H-carbazole-3,6-diamine) (DQBC); Step S23: Prepare a composite film layer of PbS quantum dot solution and D-A TADF material: Clean the silicon / silicon dioxide substrate with sulfuric acid / hydrogen peroxide solution at high temperature, then wash it with deionized water 2-3 times, and spin-coat a film by mixing the D-A TADF material solution prepared in step S22 and the PbS quantum dot solution prepared in step S21 in proportion by spin-coating, forming a composite film layer of PbS quantum dots / D-A TADF material on the surface of the silicon dioxide film, and obtaining a silicon / silicon dioxide substrate covered with a composite film layer of PbS quantum dots and D-A TADF material.

[0007] Further, in the step S21, in the lead precursor solution, the amount of lead oxide is 0.4 - 0.6 mmol, oleic acid is 1.0 - 1.2 ml, octadecene is 8 - 10 ml, the stirring temperature is 120 - 150 °C, the stirring time is 5 - 10 min. After dissolution, the temperature is raised to 270 - 300 °C; the amount of sulfur powder is 0.50 - 0.75 mmol, tri-n-octylphosphine is 1.40 - 1.70 ml, the stirring temperature is 120 - 150 °C. After dissolution, it is injected into the lead precursor three-necked flask at a rate of 1.0 - 2.0 ml / h and kept for 8 - 10 min; then the quantum dot solution is quickly cooled by a water bath, diluted with n-hexane to obtain the quantum dot solution; subsequently, during the washing process, the supernatant of the quantum dot solution is taken, and the ratio of the quantum dot supernatant to absolute ethanol is 2:1 - 1:1. The precipitate is dissolved in n-hexane, the upper layer solution is extracted, an excess of absolute ethanol is added and centrifuged at 6000 - 8000 rpm for 5 - 10 min, and then the quantum dots are dissolved in n-hexane, and the above washing process is repeated twice.

[0008] Further, in the step S22, in the synthesis solution of 6,11 - dibromodibenzo[f,h]quinoxaline, 2,7 - dibromophenanthrene - 9,10 - dione is 3.20 - 5.46 mmol, ethylenediamine is 3.20 - 5.46 mmol, acetic acid is 50 - 100 ml. They are placed in a three-necked round-bottom flask and stirred under nitrogen protection. The stirring temperature is 100 - 125 °C, and the stirring time is 18 - 36 hours. After cooling to room temperature, it is diluted with 80 - 180 ml of water, and the crude product is recrystallized with hot ethanol to obtain a white solid product, which is 6,11 - dibromodibenzo[f,h]quinoxaline; in the synthesis solution of 9,9'-(dibenzo[f,h]quinoxaline - 6,11 - diyl)bis(N³,N³,N 6 ,N 6 - tetraphenyl - 9H - carbazole - 3,6 - diamine) (DQBC), toluene is 30 - 80 ml, 6,11 - dibromodibenzo[f,h]quinoxaline is 3.12 - 4.25 mmol, N³,N³,N 6 ,N 6- The amount of tetraphenyl-9H-carbazole-3,6-diamine is 5.45 - 8.64 mmol, the amount of sodium tert-butoxide added is 9.35 - 13.25 mmol, the amount of tris(dibenzylideneacetone)dipalladium is 0.08 - 0.15 mmol, and the amount of 2-dicyclohexylphosphino-2,6'-dimethoxybiphenyl is 0.36 - 0.54 mmol. Stir under nitrogen protection, with the stirring temperature being 80 - 120 °C and the stirring time being 18 - 36 hours. After the reaction is completed and cooled, extract the mixture with dichloromethane and wash with water. Dry the organic layer with magnesium sulfate and then concentrate it under reduced pressure. The product is purified by column chromatography (the eluent is dichloromethane / petroleum ether = 1 / 4), and the obtained yellow solid is 9,9'-(dibenzo[f,h]quinoxaline-6,11-diyl)bis(N³,N³,N 6 ,N 6 - tetraphenyl-9H-carbazole-3,6-diamine) (DQBC).

[0009] Furthermore, the concentration of the prepared PbS quantum dot solution is 10 - 30 mg / ml; the PbS quantum dot / D-A TADF material includes 9,9'-(dibenzo[f,h]quinoxaline-6,11-diyl)bis(N³,N³,N 6 ,N 6 - tetraphenyl-9H-carbazole-3,6-diamine) (DQBC), meta-carbazolyl phthalimide (mCzPI), meta-methylcarbazolyl phthalimide (mMCzPI), ortho-carbazolyl phthalimide (oCzPI) and other series of D-A TADF materials that emit green light, blue light and ultraviolet light.

[0010] Furthermore, in step S23, the area of the silicon / silicon dioxide substrate is 1 cm × 1 cm; in the PbS quantum dot / D-A TADF precursor solution, the mass ratio of PbS quantum dots to D-A TADF is 4:1 - 2:1, the annealing temperature is 60 - 90 °C, the environmental condition is in a glove box with a nitrogen atmosphere where the oxygen and water are both less than 1 ppm, and the annealing time is 10 - 30 min.

[0011] Further, the specific method of step S3 is as follows: A Cr / Au composite metal electrode is formed by a patterned mask covering evaporation process on a silicon / silicon dioxide substrate covered with a PbS quantum dot / D-A TADF material composite film layer, serving as the source electrode and the drain electrode of the light-controlled thin-film transistor with a three-dimensional heterojunction quantum well composite structure of PbS quantum dots / D-A TADF materials respectively.

[0012] Further, the patterned mask covering evaporation process is to cover the surface of the silicon / silicon dioxide substrate with a PbS quantum dot / D-A TADF material composite film layer by a patterned metal mask, and then perform evaporation on its surface; the source electrode and the drain electrode are arranged on the surface of the composite film layer, and the areas of both the source electrode and the drain electrode are 200μm×300μm, and the distance therebetween is 10 - 50μm.

[0013] Further, the specific method of step S4 is as follows: By using an organic encapsulation process, a polyamic acid solution is spin-coated on the surface of the silicon / silicon dioxide substrate covered with a three-dimensional heterojunction quantum well composite film layer of PbS quantum dots / D-A TADF materials to form a film, and the polyimideization of the polyamic acid is realized by a stepped temperature heat treatment method to obtain a light-controlled thin-film transistor based on a three-dimensional heterojunction quantum well composite structure of PbS quantum dots / D-A TADF materials.

[0014] Further, the stepped temperature heat treatment method is: 120°C / 1h, 180°C / 1h, 250°C / 1h, 300°C / 1h.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a method for controllably preparing a PbS quantum dot / D-A TADF material composite layer on the surface of a silicon / silicon dioxide substrate based on a low-cost and large-area solution preparation technology, thereby preparing a novel method for fabricating a light-controlled thin-film transistor with a three-dimensional heterojunction quantum well composite channel based on a PbS quantum dot / D-A TADF material. The present invention is based on a conventional spin-coating film-forming process technology to prepare a silicon / silicon dioxide substrate, with PbS quantum dots as the quantum well region of the three-dimensional heterojunction quantum well channel and the light-irradiation carrier regulation center, and D-ATADF materials as the wide bandgap region of the three-dimensional heterojunction quantum well channel. By using the three-dimensional heterojunction quantum well and its light-irradiation means to control the carrier concentration of the composite conductive channel, using the PbS quantum dot / D-A TADF material three-dimensional heterojunction quantum well composite film layer as the conductive channel, and using metal electrodes to respectively lead out the corresponding source and drain electrodes, and finally preparing a light-controlled thin-film transistor with a three-dimensional heterojunction quantum well composite channel based on a PbS quantum dot / D-A TADF material through organic encapsulation. The preparation method of the present invention is novel, with low manufacturing cost and simple preparation process, and the device performance is flexibly controllable. The fabricated transistor has a special PbS quantum dot / D-A TADF material three-dimensional heterojunction quantum well structure and a PbS quantum dot / D-A TADF material three-dimensional heterojunction quantum well composite conductive channel layer. Therefore, the three-dimensional heterojunction quantum well of the PbS quantum dot / D-A TADF material can be fully utilized for the light field or electric field regulation effect and the quantum size effect of the PbS quantum dot, thereby effectively improving the sensitivity of the light-controlled PbS quantum dot / D-A TADF material three-dimensional heterojunction quantum well composite conductive channel thin-film transistor. Therefore, it will have very important application prospects in novel optoelectronic devices. Description of the Drawings

[0016] Figure 1 Schematic diagram of the silicon / silicon dioxide substrate structure in the embodiment of the present invention; Figure 2 Schematic diagram of the structure of a single PbS quantum dot / D-A TADF material heterojunction quantum well and its three-dimensional heterojunction quantum well composite channel layer in the embodiment of the present invention; Figure 3 Schematic diagram of the silicon / silicon dioxide substrate structure coated with a PbS quantum dot / D-A TADF material composite film layer in the embodiment of the present invention; Figure 4 Schematic diagram of the silicon / silicon dioxide substrate structure coated with a PbS quantum dot / D-A TADF material composite film layer and plated with electrodes in the embodiment of the present invention; Figure 5 Schematic diagram of the structure of a light-controlled thin-film transistor with a PbS quantum dot / D-A TADF material composite structure after encapsulation in the embodiment of the present invention; Figure 6 This is a schematic diagram of the working principle of the opto-controlled thin-film transistor based on the PbS quantum dot / D-A TADF material composite structure in the embodiments of the present invention.

[0017] Label description: 1 is the substrate silicon, 2 is the silicon dioxide film on the silicon surface, 3 is a single PbS quantum dot / D-A TADF quantum well structure, 4 is the three-dimensional heterojunction quantum well composite channel layer, 5 is the D-A TADF material, 6 is the PbS quantum dot / D-A TADF contact depletion region, 7 is the PbS quantum dot undepleted region; 8 is the source electrode, 9 is the drain electrode, 10 is the organic insulation encapsulation layer, 11 is the irradiation light direction, 12 is the PbS quantum dot / D-A TADF three-dimensional heterojunction quantum well channel region whose conductivity is enhanced by light irradiation regulation. Specific embodiments

[0018] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0019] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present application belongs.

[0020] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0021] Example 1 1) Preparation of PbS quantum dots: Add 0.6 mmol of lead oxide, 1.2 ml of oleic acid and 10 ml of octadecene to a three-necked flask, stir at 150 °C for 10 min, and then raise the temperature to 300 °C after dissolution to prepare a lead precursor solution; Take 0.75 mmol of sulfur powder and 1.70 ml of tri-n-octylphosphine, stir at 150 °C until completely dissolved, and then inject it into the three-necked flask of the lead precursor at a rate of 2.0 ml / h. After injection, keep it for 10 min; Finally, quickly cool the quantum dot solution by water bath, dilute it with n-hexane to obtain a quantum dot solution; Then take the supernatant of the quantum dot solution, the ratio of the quantum dot supernatant to absolute ethanol is 2:1, dissolve the precipitate in n-hexane, extract the upper layer solution, add an excess of absolute ethanol and centrifuge at 8000 rpm for 10 min, and then dissolve the quantum dots in n-hexane. Repeat the above cleaning process twice, dissolve the quantum dots in n-hexane to form a 30 mg / ml quantum dot solution, and store it under low-temperature conditions.

[0022] 2) Preparation of D-A TADF material (taking 9,9'-(dibenzo[f,h]quinoxaline-6,11-diyl)bis(N³,N³,N 6 ,N 6 -tetraphenyl-9H-carbazole-3,6-diamine) (DQBC) as an example): First, add 2,7-dibromophenanthrene-9,10-dione (5.46 mmol) and ethylenediamine (5.46 mmol) to 100 mL of acetic acid, and place them in a three-necked round-bottom flask. Stir at 125 °C for 36 hours under nitrogen protection. After cooling to room temperature, dilute with 180 mL of water, and recrystallize the crude product with hot ethanol to obtain a white solid product, which is 6,11-dibromodibenzo[f,h]quinoxaline. Subsequently, measure 80 mL of toluene solution, and add 6,11-dibromodibenzo[f,h]quinoxaline (4.25 mmol), N³,N³,N 6 ,N 6 -tetraphenyl-9H-carbazole-3,6-diamine (8.64 mmol) to it. Further add sodium tert-butoxide (13.25 mmol), tris(dibenzylideneacetone)dipalladium(0) (0.15 mmol) and 2-dicyclohexylphosphino-2,6'-dimethoxybiphenyl (0.54 mmol). Stir at 120 °C for 36 hours under nitrogen protection. After the reaction is completed and cooled, extract the mixture with dichloromethane and wash with water. Dry the organic layer with magnesium sulfate and concentrate it under reduced pressure. Purify the product by column chromatography (eluent: dichloromethane / petroleum ether = 1 / 4) to obtain a yellow solid, which is 9,9'-(dibenzo[f,h]quinoxaline-6,11-diyl)bis(N³,N³,N 6 ,N 6 -tetraphenyl-9H-carbazole-3,6-diamine) (DQBC).

[0023] 3) Take a silicon / silica substrate with a size of 1 cm × 1 cm and an oxide layer thickness of 30 nm, Figure 1Schematic diagram of a silicon / silicon dioxide substrate structure; where 1 is the substrate silicon and 2 is the silicon dioxide film on the silicon surface. The silicon / silicon dioxide substrate was cleaned at a high temperature in concentrated sulfuric acid / a small amount of hydrogen peroxide solution for 30 min, and then washed twice with deionized water. The PbS quantum dot colloidal solution was diluted to 30 mg / ml with n-octane, and a D-A TADF material was added to the quantum dot solution. The mass ratio of PbS quantum dots to D-A TADF in the PbS quantum dot / D-A TADF material was 4:1 to obtain a PbS quantum dot / D-A TADF mixed solution. The above-cleaned silicon / silicon dioxide substrate was spin-coated with a spin coater at a low speed of 300 rpm / s for 5 s and a high speed of 2000 rpm / s for 40 s, and then the above silicon / silicon dioxide substrate sample was annealed on a heating table at 90 °C for 30 min. Figure 2 Schematic diagram of the heterojunction quantum well of a single PbS quantum dot / D-A TADF material and its three-dimensional heterojunction quantum well composite channel layer structure; where 3 is the single PbS quantum dot / D-A TADF quantum well structure, 4 is the three-dimensional heterojunction quantum well composite channel layer, 5 is the D-A TADF material, 6 is the PbS quantum dot / D-A TADF contact depletion region, and 7 is the PbS quantum dot undepleted region. Figure 3 Schematic diagram of the silicon / silicon dioxide substrate structure coated with a PbS quantum dot / D-A TADF material composite film layer, where 1 is the substrate silicon, 2 is the silicon dioxide film on the silicon surface, 3 is the single PbS quantum dot / D-A TADF quantum well structure, 4 is the three-dimensional heterojunction quantum well composite channel layer, 5 is the D-A TADF material, 6 is the PbS quantum dot / D-A TADF contact depletion region, and 7 is the PbS quantum dot undepleted region.

[0024] 4) A Cr / Au composite metal electrode was formed by a patterned mask covering evaporation process on the silicon / silicon dioxide substrate sample coated with the PbS quantum dot / D-A TADF material composite film layer, serving as the source and drain electrodes of the optically controlled PbS quantum dot / D-A TADF material composite thin film transistor respectively; where the source and drain areas are 200 μm × 300 μm, and the distance between the source and drain is 10 μm; Figure 4 Schematic diagram of the silicon / silicon dioxide substrate structure coated with the PbS quantum dot / D-A TADF material composite film layer and plated with electrodes, where 1 is the substrate silicon, 2 is the silicon dioxide film on the silicon surface, 3 is the single PbS quantum dot / D-A TADF quantum well structure, 4 is the three-dimensional heterojunction quantum well composite channel layer, 5 is the D-A TADF material, 6 is the PbS quantum dot / D-A TADF contact depletion region, 7 is the PbS quantum dot undepleted region; 8 is the source electrode, and 9 is the drain electrode.

[0025] 5) Spin-coat the polyamic acid solution onto the silicon / silica sample with the PbS quantum dot / D-A TADF material composite film layer and electrodes deposited at a rotation speed of 1000 rpm for 60 s, and then perform corresponding heat treatment for imidization to form an organic insulating encapsulation protection layer on the PbS quantum dot / D-A TADF material composite film; Figure 5 Schematic diagram of the structure of the optically controlled thin-film transistor based on the PbS quantum dot / D-A TADF material composite structure after encapsulation. Here, 1 is the substrate silicon, 2 is the silicon dioxide film on the silicon surface, 3 is a single PbS quantum dot / D-A TADF quantum well structure, 4 is the three-dimensional heterojunction quantum well composite channel layer, 5 is the D-A TADF material, 6 is the PbS quantum dot / D-A TADF contact depletion region, 7 is the undepleted region of the PbS quantum dots; 8 is the source electrode, 9 is the drain electrode, and 10 is the organic insulating encapsulation layer. Figure 6 Schematic diagram of the working principle of the optically controlled thin-film transistor based on the PbS quantum dot / D-A TADF material composite structure. Here, 1 is the substrate silicon, 2 is the silicon dioxide film on the silicon surface, 3 is a single PbS quantum dot / D-A TADF quantum well structure, 4 is the three-dimensional heterojunction quantum well composite channel layer, 5 is the D-A TADF material, 6 is the PbS quantum dot / D-A TADF contact depletion region, 7 is the undepleted region of the PbS quantum dots; 8 is the source electrode, 9 is the drain electrode, 10 is the organic insulating encapsulation layer, 11 is the direction of the irradiation light, and 12 is the PbS quantum dot / D-A TADF three-dimensional heterojunction quantum well channel region whose conductivity is enhanced by light irradiation regulation.

[0026] Example 2 1) Preparation of PbS quantum dots: Add 0.5 mmol of lead oxide, 1.1 ml of oleic acid, and 9 ml of octadecene to a three-necked flask, stir at 135 °C for 7.5 min, and then raise the temperature to 285 °C after dissolution to prepare a lead precursor solution; Take 0.60 mmol of sulfur powder and 1.55 ml of tri-n-octylphosphine, stir at 135 °C until completely dissolved, and then inject it into the three-necked flask of the lead precursor at a rate of 1.5 ml / h. After injection, keep it for 9 min; Finally, quickly cool the quantum dot solution by water bath, dilute it with n-hexane to obtain a quantum dot solution; Then take the supernatant of the quantum dot solution, and the ratio of the quantum dot supernatant to absolute ethanol is 1.5:1. Dissolve the precipitate in n-hexane, extract the upper layer solution, add an excess of absolute ethanol and centrifuge at 7000 rpm for 7.5 min. Then dissolve the quantum dots in n-hexane, repeat the above washing process twice, dissolve the quantum dots in n-hexane to form a 20 mg / ml quantum dot solution, and store it under low-temperature conditions.

[0027] 2) Preparation of D-A TADF material (taking 9,9'-(dibenzo[f,h]quinoxaline-6,11-diyl)bis(N³,N³,N 6 ,N 6 -tetraphenyl-9H-carbazole-3,6-diamine) (DQBC) as an example): First, add 2,7-dibromophenanthrene-9,10-dione (4.20 mmol) and ethylenediamine (4.20 mmol) to 75 mL of acetic acid, and place them in a three-necked round-bottom flask. Stir at 115 °C for 27 hours under nitrogen protection. After cooling to room temperature, dilute with 130 mL of water, and recrystallize the crude product with hot ethanol to obtain a white solid product, which is 6,11-dibromodibenzo[f,h]quinoxaline. Subsequently, measure 50 mL of toluene solution, and add 6,11-dibromodibenzo[f,h]quinoxaline (3.60 mmol), N³,N³,N 6 ,N 6 -tetraphenyl-9H-carbazole-3,6-diamine (6.20 mmol) to it. Further add sodium tert-butoxide (11.25 mmol), tris(dibenzylideneacetone)dipalladium (0.12 mmol) and 2-dicyclohexylphosphino-2,6′-dimethoxybiphenyl (0.45 mmol). Stir at 100 °C for 27 hours under nitrogen protection. After the reaction is completed and cooled, extract the mixture with dichloromethane and wash with water. Dry the organic layer with magnesium sulfate and concentrate it under reduced pressure. The product is purified by column chromatography (eluent: dichloromethane / petroleum ether = 1 / 4) to obtain a yellow solid, which is 9,9'-(dibenzo[f,h]quinoxaline-6,11-diyl)bis(N³,N³,N 6 ,N 6 -tetraphenyl-9H-carbazole-3,6-diamine) (DQBC).

[0028] 3) Take a silicon / silica substrate with a size of 1 cm × 1 cm and an oxide layer thickness of 200 nm, Figure 1Schematic diagram of the silicon / silicon dioxide substrate structure; where 1 is the substrate silicon and 2 is the silicon dioxide film on the silicon surface. The silicon / silicon dioxide substrate is cleaned at a high temperature in concentrated sulfuric acid / a small amount of hydrogen peroxide solution for 30 min, and then washed twice with deionized water. The PbS quantum dot colloidal solution is diluted with n-octane to 20 mg / ml, and a D-A TADF material is added to the quantum dot solution. The mass ratio of PbS quantum dots to D-A TADF in the PbS quantum dot / D-A TADF material is 3:1 to obtain a PbS quantum dot / D-A TADF mixed solution, which is spin-coated at a low speed of 300 rpm / s for 5 s and a high speed of 2000 rpm / s for 40 s using a spin coater, and then the above glass sample is annealed on a heating table at 75 °C for 20 min. Figure 2 Schematic diagram of the heterojunction quantum well of a single PbS quantum dot / D-A TADF material and its three-dimensional heterojunction quantum well composite channel layer structure; where 3 is the single PbS quantum dot / D-A TADF quantum well structure, 4 is the three-dimensional heterojunction quantum well composite channel layer, 5 is the D-A TADF material, 6 is the PbS quantum dot / D-A TADF contact depletion region, and 7 is the undepleted region of the PbS quantum dot. Figure 3 Schematic diagram of the silicon / silicon dioxide substrate structure coated with the PbS quantum dot / D-A TADF material composite film layer, where 1 is the substrate silicon, 2 is the silicon dioxide film on the silicon surface, 3 is the single PbS quantum dot / D-A TADF quantum well structure, 4 is the three-dimensional heterojunction quantum well composite channel layer, 5 is the D-A TADF material, 6 is the PbS quantum dot / D-A TADF contact depletion region, and 7 is the undepleted region of the PbS quantum dot.

[0029] 4) A Cr / Au composite metal electrode is formed by a patterned mask covering evaporation process on the silicon / silicon dioxide substrate sample coated with the PbS quantum dot / D-A TADF material composite film layer, serving as the source and drain electrodes of the optically controlled PbS quantum dot / D-A TADF material composite thin film transistor respectively; the source and drain areas are 200 μm × 300 μm, and the distance between the source and drain is 30 μm; Figure 4 Schematic diagram of the silicon / silicon dioxide substrate structure coated with the PbS quantum dot / D-A TADF material composite film layer and plated with electrodes, where 1 is the substrate silicon, 2 is the silicon dioxide film on the silicon surface, 3 is the single PbS quantum dot / D-A TADF quantum well structure, 4 is the three-dimensional heterojunction quantum well composite channel layer, 5 is the D-A TADF material, 6 is the PbS quantum dot / D-A TADF contact depletion region, 7 is the undepleted region of the PbS quantum dot; 8 is the source electrode and 9 is the drain electrode.

[0030] 5) The polyamic acid solution was spin-coated onto the silicon / silica sample with the PbS quantum dot / D-A TADF material composite film layer and electrodes deposited thereon at a rotation speed of 2000 rpm for 60 s, and then subjected to corresponding heat treatment for imidization to form an organic insulating encapsulation protective layer on the PbS quantum dot / D-A TADF material composite film; Figure 5 Schematic diagram of the structure of the light-controlled thin-film transistor based on the PbS quantum dot / D-A TADF material composite structure after encapsulation. Here, 1 is the substrate silicon, 2 is the silicon dioxide film on the silicon surface, 3 is a single PbS quantum dot / D-A TADF quantum well structure, 4 is the three-dimensional heterojunction quantum well composite channel layer, 5 is the D-A TADF material, 6 is the PbS quantum dot / D-A TADF contact depletion region, 7 is the undepleted region of the PbS quantum dots; 8 is the source electrode, 9 is the drain electrode, and 10 is the organic insulating encapsulation layer. Figure 6 Schematic diagram of the working principle of the light-controlled thin-film transistor based on the PbS quantum dot / D-A TADF material composite structure. Here, 1 is the substrate silicon, 2 is the silicon dioxide film on the silicon surface, 3 is a single PbS quantum dot / D-A TADF quantum well structure, 4 is the three-dimensional heterojunction quantum well composite channel layer, 5 is the D-A TADF material, 6 is the PbS quantum dot / D-A TADF contact depletion region, 7 is the undepleted region of the PbS quantum dots; 8 is the source electrode, 9 is the drain electrode, 10 is the organic insulating encapsulation layer, 11 is the direction of the irradiated light, and 12 is the PbS quantum dot / D-A TADF three-dimensional heterojunction quantum well channel region whose conductivity is enhanced by light irradiation regulation.

[0031] Example 3 1) Preparation of PbS quantum dots: Add 0.4 mmol of lead oxide, 1.0 ml of oleic acid and 8 ml of octadecene to a three-necked flask, stir at 120 °C for 5 min, and then raise the temperature to 270 °C after dissolution to prepare a lead precursor solution; Take 0.50 mmol of sulfur powder and 1.40 ml of tri-n-octylphosphine, stir at 120 °C until completely dissolved, and then inject it into the three-necked flask of the lead precursor at a rate of 1.0 ml / h. After injection, maintain for 8 min; Finally, quickly cool the quantum dot solution by water bath, dilute it with n-hexane to obtain a quantum dot solution; Then take the supernatant of the quantum dot solution, and the ratio of the quantum dot supernatant to absolute ethanol is 1:1. Dissolve the precipitate in n-hexane, extract the upper layer solution, add an excess of absolute ethanol and centrifuge at 6000 rpm for 5 min. Then dissolve the quantum dots in n-hexane, repeat the above washing process twice, dissolve the quantum dots in n-hexane to form a 10 mg / ml quantum dot solution, and store it under low-temperature conditions.

[0032] 2) Preparation of D-A type TADF material (taking 9,9'-(dibenzo[f,h]quinoxaline-6,11-diyl)bis(N³,N³,N 6 ,N 6 -tetraphenyl-9H-carbazole-3,6-diamine) (DQBC) as an example): First, add 2,7-dibromophenanthrene-9,10-dione (3.20 mmol) and ethylenediamine (3.20 mmol) to 50 mL of acetic acid, and place them in a three-necked round-bottom flask. Stir at 100 °C for 18 hours under nitrogen protection. After cooling to room temperature, dilute with 80 mL of water, and recrystallize the crude product with hot ethanol to obtain a white solid product, which is 6,11-dibromodibenzo[f,h]quinoxaline. Subsequently, measure 30 mL of toluene solution, and add 6,11-dibromodibenzo[f,h]quinoxaline (3.12 mmol), N³,N³,N 6 ,N 6 -tetraphenyl-9H-carbazole-3,6-diamine (5.45 mmol) to it. Further add sodium tert-butoxide (9.35 mmol), tris(dibenzylideneacetone)dipalladium(0) (0.08 mmol) and 2-dicyclohexylphosphino-2,6'-dimethoxybiphenyl (0.36 mmol). Stir at 80 °C for 18 hours under nitrogen protection. After the reaction is completed and cooled, extract the mixture with dichloromethane and wash with water. Dry the organic layer with magnesium sulfate and concentrate under reduced pressure. Purify the product by column chromatography (eluent: dichloromethane / petroleum ether = 1 / 4) to obtain a yellow solid, which is 9,9'-(dibenzo[f,h]quinoxaline-6,11-diyl)bis(N³,N³,N 6 ,N 6 -tetraphenyl-9H-carbazole-3,6-diamine) (DQBC).

[0033] 3) Take a silicon / silicon dioxide substrate with a size of 1 cm × 1 cm and an oxide layer thickness of 300 nm. Figure 1Schematic diagram of the silicon / silicon dioxide substrate structure; where 1 is the substrate silicon and 2 is the silicon dioxide film on the silicon surface. The silicon / silicon dioxide substrate is cleaned at high temperature in concentrated sulfuric acid / a small amount of hydrogen peroxide solution for 30 min, and then washed twice with deionized water. The PbS quantum dot colloidal solution is diluted to 10 mg / ml with n-octane, and a D-A TADF material is added to the quantum dot solution. The mass ratio of PbS quantum dots to D-A TADF in the PbS quantum dot / D-A TADF material is 2:1 to obtain a PbS quantum dot / D-A TADF mixed solution, which is spin-coated at a low speed of 300 rpm / s for 5 s and a high speed of 2000 rpm / s for 40 s with a spin coater, and then the above glass slide is annealed on a heating table at 60 °C for 10 min. Figure 2 Schematic diagram of the heterojunction quantum well of a single PbS quantum dot / D-A TADF material and its three-dimensional heterojunction quantum well composite channel layer structure; where 3 is the single PbS quantum dot / D-A TADF quantum well structure, 4 is the three-dimensional heterojunction quantum well composite channel layer, 5 is the D-A TADF material, 6 is the PbS quantum dot / D-A TADF contact depletion region, and 7 is the undepleted region of PbS quantum dots. Figure 3 Schematic diagram of the silicon / silicon dioxide substrate structure coated with the PbS quantum dot / D-A TADF material composite film layer, where 1 is the substrate silicon, 2 is the silicon dioxide film on the silicon surface, 3 is the single PbS quantum dot / D-A TADF quantum well structure, 4 is the three-dimensional heterojunction quantum well composite channel layer, 5 is the D-A TADF material, 6 is the PbS quantum dot / D-A TADF contact depletion region, and 7 is the undepleted region of PbS quantum dots.

[0034] 4) A Cr / Au composite metal electrode is formed by a patterned mask covering evaporation process on the silicon / silicon dioxide substrate sample coated with the PbS quantum dot / D-A TADF material composite film layer, serving as the source and drain electrodes of the optically controlled PbS quantum dot / D-A TADF material composite thin film transistor respectively; the source and drain areas are 200 μm × 300 μm, and the distance between the source and drain is 50 μm; Figure 4 Schematic diagram of the silicon / silicon dioxide substrate structure coated with the PbS quantum dot / D-A TADF material composite film layer and plated with electrodes, where 1 is the substrate silicon, 2 is the silicon dioxide film on the silicon surface, 3 is the single PbS quantum dot / D-A TADF quantum well structure, 4 is the three-dimensional heterojunction quantum well composite channel layer, 5 is the D-A TADF material, 6 is the PbS quantum dot / D-A TADF contact depletion region, 7 is the undepleted region of PbS quantum dots; 8 is the source electrode, and 9 is the drain electrode.

[0035] 5) Spin coat the polyamic acid solution onto the silicon / silica sample that has been prepared with a PbS quantum dot / D-A TADF material composite film layer and coated with electrodes at a rotation speed of 3000 rpm for 60 s, and then perform corresponding heat treatment for imidization to form an organic insulating encapsulation protective layer on the PbS quantum dot / D-A TADF material composite film; Figure 5 Schematic diagram of the structure of the light-controlled thin-film transistor based on the PbS quantum dot / D-A TADF material composite structure after encapsulation. Here, 1 is the substrate silicon, 2 is the silicon dioxide film on the silicon surface, 3 is a single PbS quantum dot / D-A TADF quantum well structure, 4 is the three-dimensional heterojunction quantum well composite channel layer, 5 is the D-A TADF material, 6 is the PbS quantum dot / D-A TADF contact depletion region, 7 is the undepleted region of the PbS quantum dots; 8 is the source electrode, 9 is the drain electrode, and 10 is the organic insulating encapsulation layer. Figure 6 Schematic diagram of the working principle of the light-controlled thin-film transistor based on the PbS quantum dot / D-A TADF material composite structure. Here, 1 is the substrate silicon, 2 is the silicon dioxide film on the silicon surface, 3 is a single PbS quantum dot / D-A TADF quantum well structure, 4 is the three-dimensional heterojunction quantum well composite channel layer, 5 is the D-A TADF material, 6 is the PbS quantum dot / D-A TADF contact depletion region, 7 is the undepleted region of the PbS quantum dots; 8 is the source electrode, 9 is the drain electrode, 10 is the organic insulating encapsulation layer, 11 is the direction of the irradiated light, and 12 is the PbS quantum dot / D-A TADF three-dimensional heterojunction quantum well channel region whose conductivity is enhanced by light irradiation regulation.

[0036] As mentioned above, it is only a preferred embodiment of the present invention, and it is not a limitation of the present invention in other forms. Any person skilled in the art may use the disclosed technical content to make changes or modifications into equivalent embodiments with equivalent changes. However, any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention without departing from the technical solution content of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing a light-controlled thin-film transistor based on a three-dimensional heterojunction quantum well composite channel of PbS quantum dots / D-A TADF material, characterized in that, It includes the following steps: Step S1: Select a silicon / silicon dioxide substrate, where the silicon / silicon dioxide substrate includes substrate silicon and a silicon dioxide film disposed on the surface of the substrate silicon; Step S2: Prepare a PbS quantum dot solution and a D-A TADF material solution, and prepare a three-dimensional heterojunction quantum well composite film layer of PbS quantum dots / D-A TADF material on the silicon / silicon dioxide substrate to be used as a conductive channel; Step S3: Prepare metal electrodes on the silicon / silicon dioxide substrate covered with the three-dimensional heterojunction quantum well composite film of PbS quantum dots / D-A TADF material to obtain the source and drain electrodes of the photoconductive thin-film transistor with a three-dimensional heterojunction quantum well composite structure of PbS quantum dots / D-A TADF material; Step S4: Use organic encapsulation to fabricate a thin-film transistor based on a photoconductive three-dimensional heterojunction quantum well composite conductive channel of PbS quantum dots / D-A TADF material, and use light illumination means to control the carrier concentration of the conductive channel.

2. The preparation method of the light-controlled thin-film transistor based on the three-dimensional heterojunction quantum well composite channel of PbS quantum dots / D-A TADF materials according to claim 1, wherein The specific method of Step S2 includes the following steps: Step S21: Prepare a PbS quantum dot solution: Dissolve a set amount of lead oxide, oleic acid, and octadecene at a set temperature to prepare a lead precursor solution; Dissolve a set amount of sulfur powder in trioctylphosphine and inject it into a three-necked flask at a set speed, then quickly cool the quantum dot solution by means of a water bath, dilute it with n-hexane, obtain the quantum dot solution, and store it under low-temperature conditions; Take out a part of the supernatant of the quantum dot solution after standing, then add an appropriate amount of n-hexane solution and take out the upper layer solution, add absolute ethanol for centrifugation, and then dissolve the precipitate with n-hexane to obtain a purified quantum dot solution; Step S22: Prepare the D-A TADF material solution: First, take a set amount of 2,7-dibromophenanthrene-9,10-dione and ethylenediamine and add them to an appropriate amount of acetic acid. Place them in a three-necked round-bottom flask and stir for a corresponding time at a set temperature under nitrogen protection. Cool to room temperature, dilute with an appropriate amount of water, and recrystallize the crude product with hot ethanol to obtain the white solid product 6,11-dibromodibenzo[f,h]quinoxaline; measure a set volume of toluene solution, and add a set amount of 6,11-dibromodibenzo[f,h]quinoxaline, N³,N³,N 6 ,N 6 -tetraphenyl-9H-carbazole-3,6-diamine. Further add a set amount of sodium tert-butoxide, tris(dibenzylideneacetone)dipalladium, and 2-dicyclohexylphosphino-2,6′-dimethoxybiphenyl, and stir for a corresponding time at a set temperature under nitrogen protection. After the reaction is completed and cooled, extract the mixture with dichloromethane and wash with water. Dry the organic layer with magnesium sulfate and concentrate under reduced pressure. Purify the product by column chromatography to obtain the yellow solid, which is 9,9'-(dibenzo[f,h]quinoxaline-6,11-diyl)bis(N³,N³,N 6 ,N 6 -tetraphenyl-9H-carbazole-3,6-diamine); Step S23: Prepare a composite film layer of PbS quantum dot solution and D-A TADF material: Clean the silicon / silicon dioxide substrate with sulfuric acid / hydrogen peroxide solution at high temperature, then wash it with deionized water 2-3 times, and use the spin-coating process to spin-coat a film by mixing the D-A TADF material solution prepared in Step S22 and the PbS quantum dot solution prepared in Step S21 in proportion on the silicon dioxide film surface to form a composite film layer of PbS quantum dots / D-A TADF material on the silicon dioxide film surface, and obtain a silicon / silicon dioxide substrate covered with a composite film layer of PbS quantum dots and D-ATADF material.

3. The method for preparing a light-controlled thin-film transistor based on a three-dimensional heterojunction quantum well composite channel of PbS quantum dots / D-A TADF materials according to claim 2, characterized in that, In the step S21, in the lead precursor solution, the amount of lead oxide is 0.4 - 0.6 mmol, the amount of oleic acid is 1.0 - 1.2 ml, the amount of octadecene is 8 - 10 ml, the stirring temperature is 120 - 150 °C, the stirring time is 5 - 10 min. After dissolution, the temperature is raised to 270 - 300 °C; the amount of sulfur powder is 0.50 - 0.75 mmol, the amount of tri-n-octylphosphine is 1.40 - 1.70 ml, the stirring temperature is 120 - 150 °C. After dissolution, it is injected into the lead precursor three-necked flask at a rate of 1.0 - 2.0 ml / h and kept for 8 - 10 min; then the quantum dot solution is quickly cooled by a water bath, diluted with n-hexane to obtain the quantum dot solution; subsequently, during the cleaning process, the supernatant of the quantum dot solution is taken, and the ratio of the quantum dot supernatant to absolute ethanol is 2:1 - 1:

1. The precipitate is dissolved in n-hexane, the upper layer solution is extracted, an excessive amount of absolute ethanol is added, and it is centrifuged at 6000 - 8000 rpm for 5 - 10 min. Then the quantum dots are dissolved with n-hexane, and the above cleaning process is repeated twice.

4. The method for preparing a light-controlled thin-film transistor based on a three-dimensional heterojunction quantum well composite channel of PbS quantum dots / D-A TADF material according to claim 2, wherein, In the step S22, in the synthesis solution of 6,11-dibromodibenzo[f,h]quinoxaline, 2,7-dibromophenanthrene-9,10-dione is 3.20 - 5.46 mmol, ethylenediamine is 3.20 - 5.46 mmol, acetic acid is 50 - 100 ml. They are placed in a three-necked round-bottom flask and stirred under nitrogen protection. The stirring temperature is 100 - 125 °C, and the stirring time is 18 - 36 hours. After cooling to room temperature, it is diluted with 80 - 180 ml of water, and the crude product is recrystallized with hot ethanol to obtain a white solid product, which is 6,11-dibromodibenzo[f,h]quinoxaline; in the synthesis solution of 9,9'-(dibenzo[f,h]quinoxaline-6,11-diyl)bis(N³,N³,N 6 ,N 6 -tetraphenyl-9H-carbazole-3,6-diamine), toluene is 30 - 80 ml, 6,11-dibromodibenzo[f,h]quinoxaline is 3.12 - 4.25 mmol, N³,N³,N 6 ,N 6 -tetraphenyl-9H-carbazole-3,6-diamine is 5.45 - 8.64 mmol, the added sodium tert-butoxide is 9.35 - 13.25 mmol, tris(dibenzylideneacetone)dipalladium is 0.08 - 0.15 mmol, 2-dicyclohexylphosphino-2,6′-dimethoxybiphenyl is 0.36 - 0.54 mmol. It is stirred under nitrogen protection. The stirring temperature is 80 - 120 °C, and the stirring time is 18 - 36 hours. After the reaction is completed and cooled, the mixture is extracted with dichloromethane and washed with water. The organic layer is dried with magnesium sulfate and concentrated under reduced pressure. The product is purified by column chromatography, and the obtained yellow solid is 9,9'-(dibenzo[f,h]quinoxaline-6,11-diyl)bis(N³,N³,N 6 ,N 6 -tetraphenyl-9H-carbazole-3,6-diamine).

5. The preparation method of the optically controlled thin-film transistor based on the three-dimensional heterojunction quantum well composite channel of PbS quantum dots / D-A TADF materials according to claim 2, characterized in that The concentration of the prepared PbS quantum dot solution is 10 - 30 mg / ml; the PbS quantum dot / D-A TADF material includes 9,9'-(dibenzo[f,h]quinoxaline-6,11-diyl)bis(N³,N³,N 6 ,N 6 -tetraphenyl-9H-carbazole-3,6-diamine), m-carbazolylphthalimide, m-methylcarbazolylphthalimide, o-carbazolylphthalimide series of D-A TADF materials that emit green light, blue light and ultraviolet light.

6. The preparation method of the light-controlled thin film transistor based on the three-dimensional heterojunction quantum well composite channel of PbS quantum dots / D-A TADF materials according to claim 2, characterized in that, In the step S23, the area of the silicon / silicon dioxide substrate is 1 cm × 1 cm; in the PbS quantum dot / D-A TADF precursor solution, the mass ratio of PbS quantum dots to D-A TADF is 4:1 - 2:1, the annealing temperature is 60 - 90 °C, the environmental condition is in a glove box with a nitrogen atmosphere where both oxygen and water are less than 1 ppm, and the annealing time is 10 - 30 min.

7. The method for preparing a light-controlled thin-film transistor based on a three-dimensional heterojunction quantum well composite channel of PbS quantum dots / D-A TADF materials according to claim 1, wherein The specific method of the step S3 is: A Cr / Au composite metal electrode is formed on the silicon / silicon dioxide substrate covered with the PbS quantum dot / D-A TADF material composite film layer by a patterned mask covering evaporation process, which are respectively used as the source electrode and the drain electrode of the PbS quantum dot / D-A TADF material three-dimensional heterojunction quantum well composite structure optoelectronic thin film transistor.

8. The method for preparing a light-controlled thin-film transistor based on a three-dimensional heterojunction quantum well composite channel of PbS quantum dots / D-A TADF material according to claim 7, wherein, The patterned mask covering evaporation process is to cover the surface of the silicon / silicon dioxide substrate with the PbS quantum dot / D-A TADF material composite film layer with a patterned metal mask, and then perform evaporation on its surface; the source electrode and the drain electrode are arranged on the surface of the composite film layer, and the areas of both the source electrode and the drain electrode are 200 μm × 300 μm, and the spacing is 10 - 50 μm.

9. The preparation method of the light-controlled thin-film transistor based on the three-dimensional heterojunction quantum well composite channel of PbS quantum dots / D-A TADF materials according to claim 1, wherein, The specific method of the step S4 is: By using an organic encapsulation process, a polyamic acid solution is spin-coated on the surface of the silicon / silicon dioxide substrate covered with the PbS quantum dot / D-A TADF material three-dimensional heterojunction quantum well composite film layer to form a film, and the polyamic acid is polyimidized by a stepped temperature heat treatment method to obtain an optoelectronic thin film transistor based on the PbS quantum dot / D-A TADF material three-dimensional heterojunction quantum well composite structure.

10. The method for preparing a light-controlled thin-film transistor based on a three-dimensional heterojunction quantum well composite channel of PbS quantum dots / D-A TADF materials according to claim 9, wherein The stepped temperature heat treatment method is: 120 °C / 1 h, 180 °C / 1 h, 250 °C / 1 h, 300 °C / 1 h.

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