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

Abstract

The invention relates to a preparation method of a light-operated thin film transistor based on a TADF / PbS quantum dot / TADF material laminated heterojunction quantum well composite channel, and the method comprises the steps: preparing a TADF / PbS quantum dot / TADF material laminated 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 the light-operated thin film transistor based on the TADF / PbS quantum dot / TADF material laminated heterojunction quantum well composite channel. Cr / Au composite metal electrodes are respectively formed on the TADF / PbS quantum dot / TADF material laminated 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 TADF / PbS quantum dot / TADF material laminated 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 TADF / PbS quantum dot / TADF material laminated 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 an optically controlled thin film transistor based on a stacked heterojunction quantum well composite channel of a TADF / PbS quantum dot / TADF material. 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. Such traditional thin film field effect transistors based on silicon microelectronic technology have problems such as high requirements for equipment, complex preparation processes, high costs, limited overall device performance, and 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 difficult to meet the current information society's demand for thin film field effect transistors with high sensitivity, high switching frequency, and switching speed.

[0003] In recent years, nanocrystalline 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 optically controlled thin film transistor based on a quantum dot conductive channel. In addition, a thin film field effect transistor based on a stacked heterojunction quantum well composite channel formed by laminating another organic semiconductor material with a large energy band difference with a quantum dot can form an effectively controllable depletion layer and its stacked quantum well structure between the stacked heterojunction quantum well composite channels, thereby effectively regulating the carrier concentration and conductivity of this organic semiconductor / quantum dot / organic semiconductor laminated 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 new idea for the development of a preparation method of an optically controlled thin film transistor based on a semiconductor material / quantum dot / semiconductor material stacked heterojunction quantum well composite channel. Summary of the Invention

[0004] The object of the present invention is to provide a method for preparing a light-controlled thin-film transistor based on a stacked heterojunction quantum well composite channel of TADF / PbS quantum dots / TADF material in view of the deficiencies and defects of the prior art. This method has low manufacturing cost and simple preparation process, and can make full use of the light field or electric field regulation effect of the stacked heterojunction quantum well of TADF / PbS quantum dots / TADF material and the quantum size effect of the quantum dots themselves, thereby effectively improving the sensitivity of the light-controlled thin-film transistor with a stacked heterojunction quantum well composite channel of PTADF / PbS quantum dots / TADF material.

[0005] To achieve the above object, the technical solution adopted by the present invention is: A method for preparing a light-controlled thin-film transistor based on a stacked heterojunction quantum well composite channel of TADF / PbS quantum dots / TADF material, 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-A TADF material solution; and prepare a stacked heterojunction quantum well composite film layer of TADF / PbS quantum dots / 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 stacked heterojunction quantum well composite film of TADF / PbS quantum dots / TADF material to obtain the source and drain electrodes of the light-controlled thin-film transistor with a stacked heterojunction quantum well composite structure of TADF / PbS quantum dots / TADF material; Step S4: Use organic encapsulation to prepare a thin-film transistor based on a light-controlled stacked heterojunction quantum well composite conductive channel of TADF / PbS quantum dots / TADF material, and use light illumination means to control the carrier concentration of the conductive channel.

[0006] Further, the specific steps of step S2 are as follows: 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-A TADF material solution (using 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, 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 together in a three-necked round-bottom flask, 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 the 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. The product is purified 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 TADF / PbS quantum dot / TADF material laminated heterojunction composite film layer: Clean the silicon / silicon dioxide substrate with a 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 layer of D-A TADF material solution prepared in step S22 on the cleaned silicon / silicon dioxide substrate to form a D-A TADF material thin film; use the spin-coating process to spin-coat a layer of PbS quantum dot film on the silicon / silicon dioxide substrate sample that has been spin-coated with the D-A TADF material thin film with the PbS quantum dot solution prepared in step S21; use the spin-coating process to continue spin-coating a layer of D-A TADF film on the silicon / silicon dioxide substrate sample that has been spin-coated with the D-A TADF / PbS quantum dot composite film, and form a TADF / PbS quantum dot / TADF material laminated heterojunction composite film layer on the surface of the silicon dioxide film, and obtain a silicon / silicon dioxide substrate covered with the TADF / PbS quantum dot / TADF material laminated heterojunction composite film layer.

[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, trioctylphosphine 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 water bath, diluted with n-hexane to obtain the quantum dot solution; subsequently, 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. Then the quantum dots are dissolved in n-hexane, and the above cleaning process is repeated twice.

[0008] Further, in the step S22, in the 6,11-dibromodibenzo[f,h]quinoxaline synthesis solution, 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. All 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 9,9'-(dibenzo[f,h]quinoxaline-6,11-diyl)bis(N³,N³,N 6 ,N 6 - tetraphenyl-9H-carbazole-3,6-diamine) (DQBC) synthesis solution, 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, sodium tert-butoxide added 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. Stir 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 (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 TADF / PbS quantum dot / 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-carbazolylphthalimide (mCzPI), meta-methylcarbazolylphthalimide (mMCzPI), ortho-carbazolylphthalimide (oCzPI) and other series of D-A TADF materials that emit green light, blue light and ultraviolet light.

[0010] Furthermore, in the step S23, the area of the silicon / silicon dioxide substrate is 1 cm × 1 cm; in the first and second layer TADF film-forming processes, the concentration of the D-A TADF material solution is 15 - 40 mg / ml, 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; in the PbS quantum dot film-forming process, the concentration of the PbS quantum dot solution is 10 - 25 mg / ml, 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.

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

[0012] Further, the patterned mask covering evaporation process is to cover the surface of a silicon / silicon dioxide substrate with a TADF / PbS quantum dot / TADF material laminated heterojunction 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 distance therebetween is 10 - 50 μm.

[0013] Further, the specific method of step S4 is as follows: An organic encapsulation process is adopted to spin-coat a polyamic acid solution on the surface of a silicon / silicon dioxide substrate covered with a TADF / PbS quantum dot / TADF material laminated heterojunction quantum well composite film layer to form a film, and the polyimide formation of the polyamic acid is realized by using a stepwise temperature heat treatment method to obtain an optically controlled thin-film transistor based on a TADF / PbS quantum dot / TADF material laminated heterojunction quantum well composite channel.

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

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a method for controllably preparing a TADF / PbS quantum dot / TADF material laminated 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 based on a TADF / PbS quantum dot / TADF material laminated heterojunction quantum well composite channel. The present invention is based on a conventional spin-coating film-forming process technology to prepare a silicon / silicon dioxide substrate, using a TADF / PbS quantum dot / TADF material as the laminated heterojunction quantum well channel well region and the light irradiation carrier regulation center, using a D-A TADF material as the wide bandgap region of the laminated heterojunction quantum well channel, using the laminated heterojunction quantum well and its light irradiation means to control the carrier concentration of the composite conductive channel, using the TADF / PbS quantum dot / TADF material laminated heterojunction quantum well composite film layer as the conductive channel, leading out the corresponding source electrode and drain electrode with metal electrodes respectively, and finally preparing a light-controlled thin-film transistor based on the TADF / PbS quantum dot / TADF material laminated heterojunction quantum well composite channel 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 prepared transistor has a special TADF / PbS quantum dot / TADF material laminated heterojunction quantum well structure and a TADF / PbS quantum dot / TADF material laminated heterojunction quantum well composite conductive channel layer. Therefore, the light field or electric field regulation effect of the TADF / PbS quantum dot / TADF material laminated heterojunction quantum well and the quantum size effect of the PbS quantum dot can be fully utilized, thereby effectively improving the sensitivity of the light-controlled TADF / PbS quantum dot / TADF material laminated heterojunction quantum well composite conductive channel thin-film transistor. Therefore, it will have a very important application prospect in novel optoelectronic devices. BRIEF 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, a quantum dot / D-A TADF material heterojunction quantum well, and its laminated 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 TADF-PbS quantum dot-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 TADF-PbS quantum dot-TADF material composite film layer and plated with electrodes in the embodiment of the present invention; Figure 5Schematic diagram of the structure of the optically controlled thin-film transistor with a TADF-PbS quantum dot-TADF material stacked heterojunction composite structure after encapsulation in the embodiment of the present invention; Figure 6 Schematic diagram of the working principle of the optically controlled thin-film transistor with a TADF-PbS quantum dot-TADF material stacked heterojunction composite structure in the embodiment of the present invention.

[0017] Reference numeral description: 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 material heterojunction quantum well structure on the upper surface of the channel layer, 4 is the single PbS quantum dot structure in the middle of the channel layer, 5 is the single PbS quantum dot / D-A TADF material heterojunction quantum well structure on the lower surface of the channel layer, 6 is the stacked heterojunction quantum well composite light-emitting layer, 7 is the D-A TADF material, 8 is the PbS quantum dot / D-A TADF contact depletion region, 9 is the undepleted region of the PbS quantum dot, 10 is the source electrode, 11 is the drain electrode, 12 is the organic insulating encapsulation layer, 13 is the irradiation light direction, and 14 is the TADF-PbS quantum dot-TADF material stacked heterojunction quantum well channel region with enhanced conductivity regulated by light irradiation. Detailed implementation manners

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

[0019] It should be noted that the following detailed description is exemplary and is intended to provide further illustration 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 this application belongs.

[0020] It should be noted that the terms used herein are only for describing specific implementation manners 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 forms are also intended to include the plural forms. 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] Embodiment 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 into a three-necked flask, stir at 150 °C for 10 min, and after dissolution, raise the temperature to 300 °C 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, and keep it for 10 min after injection; 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 materials (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, 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) thereto, 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 under reduced pressure, and purify the product by column chromatography (the eluent is 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 / silicon dioxide substrate with a size of 1 cm × 1 cm and an oxide layer thickness of 30 nm. Figure 1 It is a schematic 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. Clean the silicon / silicon dioxide substrate in concentrated sulfuric acid / a small amount of hydrogen peroxide solution at high temperature for 30 min, and then wash it twice with deionized water. Dilute the D - A TADF material with n - octane to 40 mg / ml, and spin - coat it 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. Then place the silicon / silicon dioxide sample coated with a layer of TADF film on a heating table and anneal it at 90 °C for 30 min.

[0024] 4) Dilute the PbS quantum dot colloidal solution with n - octane to a 25 mg / ml solution, and spin - coat it 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. Then place the silicon / silicon dioxide sample coated with the TADF / PbS quantum dot composite layer on a heating table and anneal it at 90 °C for 30 min.

[0025] 5) Dilute the D - A TADF material with n - octane to 40 mg / ml, and spin - coat it 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. Then place the silicon / silicon dioxide sample coated with the TADF / PbS quantum dot / TADF stacked composite layer on a heating table and anneal it at 90 °C for 30 min. Figure 2 It is a structural diagram of a single PbS quantum dot, a quantum dot / D - A TADF material heterojunction quantum well, and its stacked heterojunction quantum well composite channel layer; where 3 is the structure of a single PbS quantum dot / D - A TADF material heterojunction quantum well on the upper surface of the channel layer, 4 is the structure of a single PbS quantum dot in the middle of the channel layer, 5 is the structure of a single PbS quantum dot / D - A TADF material heterojunction quantum well on the lower surface of the channel layer, 6 is the stacked heterojunction quantum well composite light - emitting layer, 7 is the D - A TADF material, 8 is the PbS quantum dot / D - A TADF contact depletion region, and 9 is the PbS quantum dot undepleted region. Figure 3Schematic diagram of the silicon / silicon dioxide substrate structure after coating with a composite film layer of TADF-PbS quantum dot-TADF material; 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 material heterojunction quantum well structure on the upper surface of the channel layer, 4 is the single PbS quantum dot structure in the middle of the channel layer, 5 is the single PbS quantum dot / D-A TADF material heterojunction quantum well structure on the lower surface of the channel layer, 6 is the stacked heterojunction quantum well composite light-emitting layer, 7 is the D-A TADF material, 8 is the PbS quantum dot / D-A TADF contact depletion region, and 9 is the undepleted region of the PbS quantum dot.

[0026] 6) 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 TADF / PbS quantum dot / TADF stacked composite film layer, serving as the source and drain electrodes of the optically controlled TADF / PbS quantum dot / TADF stacked composite thin film transistor respectively; where the source and drain areas are 200μm×300μm, and the distance between the source and drain is 10μm; Figure 4 Schematic diagram of the silicon / silicon dioxide substrate structure after coating with a composite film layer of TADF-PbS quantum dot-TADF material and plating 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 material heterojunction quantum well structure on the upper surface of the channel layer, 4 is the single PbS quantum dot structure in the middle of the channel layer, 5 is the single PbS quantum dot / D-A TADF material heterojunction quantum well structure on the lower surface of the channel layer, 6 is the stacked heterojunction quantum well composite light-emitting layer, 7 is the D-A TADF material, 8 is the PbS quantum dot / D-A TADF contact depletion region, 9 is the undepleted region of the PbS quantum dot, 10 is the source electrode, and 11 is the drain electrode.

[0027] 7) The polyamic acid solution is spin-coated onto the silicon / silicon dioxide sample that has been prepared with the TADF / PbS quantum dot / TADF stacked composite film layer and plated with electrodes at a rotation speed of 1000 rpm for 60 s, and then undergoes corresponding heat treatment for imidization to form an organic insulating encapsulation protection layer on the TADF-PbS quantum dot-TADF material stacked heterojunction composite film; Figure 5Schematic diagram of the structure of a light-controlled thin-film transistor based on a stacked heterojunction composite structure of TADF-PbS quantum dots-TADF materials after encapsulation. Among them, 1 is the substrate silicon, 2 is the silicon dioxide film on the silicon surface, 3 is the single PbS quantum dot / D-ATADF material heterojunction quantum well structure on the upper surface of the channel layer, 4 is the single PbS quantum dot structure in the middle of the channel layer, 5 is the single PbS quantum dot / D-A TADF material heterojunction quantum well structure on the lower surface of the channel layer, 6 is the stacked heterojunction quantum well composite light-emitting layer, 7 is the D-ATADF material, 8 is the PbS quantum dot / D-A TADF contact depletion region, 9 is the PbS quantum dot undepleted region, 10 is the source electrode, 11 is the drain electrode, and 12 is the organic insulation encapsulation layer. Figure 6 Schematic diagram of the working principle of a light-controlled thin-film transistor based on a stacked heterojunction composite structure of TADF-PbS quantum dots-TADF materials. Among them, 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 material heterojunction quantum well structure on the upper surface of the channel layer, 4 is the single PbS quantum dot structure in the middle of the channel layer, 5 is the single PbS quantum dot / D-A TADF material heterojunction quantum well structure on the lower surface of the channel layer, 6 is the stacked heterojunction quantum well composite light-emitting layer, 7 is the D-A TADF material, 8 is the PbS quantum dot / D-A TADF contact depletion region, 9 is the PbS quantum dot undepleted region, 10 is the source electrode, 11 is the drain electrode, 12 is the organic insulation encapsulation layer, 13 is the irradiation light direction, and 14 is the TADF-PbS quantum dot-TADF material stacked heterojunction quantum well channel region whose conductivity is enhanced by light irradiation regulation.

[0028] 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 into 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 trioctylphosphine, stir at 135 °C until completely dissolved, and then inject it into the three-necked flask of the lead precursor at a speed of 1.5 ml / h, and keep it for 9 min after injection; 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, 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 20 mg / ml quantum dot solution, and store it under low-temperature conditions.

[0029] 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) (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 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).

[0030] 3) Take a silicon / silicon dioxide substrate with a size of 1 cm × 1 cm and an oxide layer thickness of 200 nm, Figure 1 which is a schematic 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. Clean the silicon / silicon dioxide substrate in a concentrated sulfuric acid / small amount of hydrogen peroxide solution at high temperature for 30 min, and then wash it twice with deionized water. Dilute the D-A TADF material with n-octane to 25 mg / ml, and spin-coat it 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. Then place the silicon / silicon dioxide sample coated with the TADF thin film on a heating table and anneal it at 75 °C for 20 min.

[0031] 4) Dilute the PbS quantum dot colloidal solution with n-octane to a 25 mg / ml solution, and spin-coat it 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. Then, place the silicon / silica sample coated with the TADF / PbS quantum dot stacked composite film on a heating stage and anneal it at 75 °C for 20 min.

[0032] 5) Dilute the D-A TADF material with n-octane to 25 mg / ml, and spin-coat it 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. Then, place the silicon / silica sample coated with the TADF / PbS quantum dot / TADF stacked heterojunction composite film on a heating stage and anneal it at 75 °C for 20 min. Figure 2 It is a structural diagram of a single PbS quantum dot, a quantum dot / D-A TADF material heterojunction quantum well, and their stacked heterojunction quantum well composite channel layers; where 3 is the structure of a single PbS quantum dot / D-A TADF material heterojunction quantum well on the upper surface of the channel layer, 4 is the structure of a single PbS quantum dot in the middle of the channel layer, 5 is the structure of a single PbS quantum dot / D-A TADF material heterojunction quantum well on the lower surface of the channel layer, 6 is the stacked heterojunction quantum well composite light-emitting layer, 7 is the D-A TADF material, 8 is the PbS quantum dot / D-A TADF contact depletion region, and 9 is the undepleted region of the PbS quantum dot. Figure 3 It is a schematic diagram of the silicon / silica substrate structure after coating with the TADF-PbS quantum dot-TADF material composite film layer; where 1 is the substrate silicon, 2 is the silicon dioxide film on the silicon surface, 3 is the structure of a single PbS quantum dot / D-ATADF material heterojunction quantum well on the upper surface of the channel layer, 4 is the structure of a single PbS quantum dot in the middle of the channel layer, 5 is the structure of a single PbS quantum dot / D-A TADF material heterojunction quantum well on the lower surface of the channel layer, 6 is the stacked heterojunction quantum well composite light-emitting layer, 7 is the D-ATADF material, 8 is the PbS quantum dot / D-A TADF contact depletion region, and 9 is the undepleted region of the PbS quantum dot.

[0033] 6) On the silicon / silica substrate sample prepared with the TADF / PbS quantum dot / TADF stacked heterojunction composite film layer, use a patterned mask covering evaporation process to form Cr / Au composite metal electrodes, which are used as the source and drain electrodes of the optically controlled TADF / PbS quantum dot / TADF stacked heterojunction 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 30 μm; Figure 4Schematic diagram of the silicon / silicon dioxide substrate structure after coating with a composite film layer of TADF-PbS quantum dots-TADF material and plating 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 material heterojunction quantum well structure on the upper surface of the channel layer, 4 is the single PbS quantum dot structure in the middle of the channel layer, 5 is the single PbS quantum dot / D-A TADF material heterojunction quantum well structure on the lower surface of the channel layer, 6 is the stacked heterojunction quantum well composite light-emitting layer, 7 is the D-A TADF material, 8 is the PbS quantum dot / D-A TADF contact depletion region, 9 is the PbS quantum dot undepleted region, 10 is the source electrode, and 11 is the drain electrode.

[0034] 7) Spin-coat the polyamic acid solution onto the silicon / silicon dioxide sample that has been prepared with a TADF / PbS quantum dot / TADF stacked heterojunction composite film layer and plated electrodes at a rotation speed of 2000 rpm and a spin-coating time of 60 s, and perform corresponding heat treatment for imidization, that is, form an organic insulating encapsulation protective layer on the TADF / PbS quantum dot / TADF stacked heterojunction composite film; Figure 5 Schematic diagram of the structure of the optically controlled thin-film transistor based on the TADF-PbS quantum dot-TADF material stacked heterojunction composite structure after encapsulation. Among them, 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 material heterojunction quantum well structure on the upper surface of the channel layer, 4 is the single PbS quantum dot structure in the middle of the channel layer, 5 is the single PbS quantum dot / D-A TADF material heterojunction quantum well structure on the lower surface of the channel layer, 6 is the stacked heterojunction quantum well composite light-emitting layer, 7 is the D-A TADF material, 8 is the PbS quantum dot / D-A TADF contact depletion region, 9 is the PbS quantum dot undepleted region, 10 is the source electrode, 11 is the drain electrode, and 12 is the organic insulating encapsulation layer. Figure 6 Schematic diagram of the working principle of the optically controlled thin-film transistor based on the TADF-PbS quantum dot-TADF material stacked heterojunction composite structure. Among them, 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 material heterojunction quantum well structure on the upper surface of the channel layer, 4 is the single PbS quantum dot structure in the middle of the channel layer, 5 is the single PbS quantum dot / D-A TADF material heterojunction quantum well structure on the lower surface of the channel layer, 6 is the stacked heterojunction quantum well composite light-emitting layer, 7 is the D-A TADF material, 8 is the PbS quantum dot / D-A TADF contact depletion region, 9 is the PbS quantum dot undepleted region, 10 is the source electrode, 11 is the drain electrode, 12 is the organic insulating encapsulation layer, 13 is the direction of the irradiation light, and 14 is the TADF-PbS quantum dot-TADF material stacked heterojunction quantum well channel region where the conductivity is enhanced by light irradiation regulation.

[0035] 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 into a three-necked flask, stir at 120 °C for 5 min, and after dissolution, raise the temperature to 270 °C to prepare a lead precursor solution; take 0.50 mmol of sulfur powder and 1.40 ml of trioctylphosphine, 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, keep it for 8 min; finally, quickly cool the quantum dot solution by means of a 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, and 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.

[0036] 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 (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, and further add sodium tert-butoxide (9.35 mmol), tris (dibenzylideneacetone) dipalladium (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 it with water. The organic layer is dried with magnesium sulfate and concentrated 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 ,N6 - tetraphenyl - 9H - carbazole - 3,6 - diamine) (DQBC).

[0037] 4) Take a silicon / silicon dioxide substrate with a size of 1 cm×1 cm and an oxide layer thickness of 300 nm. Figure 1 It is a schematic 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 in concentrated sulfuric acid / a small amount of hydrogen peroxide solution at high temperature for 30 min, and then washed twice with deionized water. The D-A TADF material is diluted with n-octane to 15 mg / ml, and 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. Then, the silicon / silicon dioxide sample coated with the TADF film is placed on a heating table and annealed at 60 °C for 10 min.

[0038] 5) Dilute the PbS quantum dot colloidal solution with n-octane to a 10 mg / ml solution, and spin-coat it 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. Then, the silicon / silicon dioxide sample coated with the TADF / PbS quantum dot stacked heterojunction film is placed on a heating table and annealed at 60 °C for 10 min.

[0039] 6) Dilute the D-A TADF material with n-octane to 15 mg / ml, and spin-coat it 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. Then, the silicon / silicon dioxide sample coated with the TADF / PbS quantum dot / TADF stacked heterojunction film is placed on a heating table and annealed at 60 °C for 10 min. Figure 2 It is a structural diagram of a single PbS quantum dot, a quantum dot / D-A TADF material heterojunction quantum well, and its stacked heterojunction quantum well composite channel layer; where 3 is the structure of a single PbS quantum dot / D-A TADF material heterojunction quantum well on the upper surface of the channel layer, 4 is the structure of a single PbS quantum dot in the middle of the channel layer, 5 is the structure of a single PbS quantum dot / D-A TADF material heterojunction quantum well on the lower surface of the channel layer, 6 is the stacked heterojunction quantum well composite light-emitting layer, 7 is the D-A TADF material, 8 is the PbS quantum dot / D-A TADF contact depletion region, and 9 is the PbS quantum dot undepleted region. Figure 3Schematic diagram of the silicon / silicon dioxide substrate structure after coating with the TADF-PbS quantum dot-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 material heterojunction quantum well structure on the upper surface of the channel layer, 4 is the single PbS quantum dot structure in the middle of the channel layer, 5 is the single PbS quantum dot / D-A TADF material heterojunction quantum well structure on the lower surface of the channel layer, 6 is the stacked heterojunction quantum well composite light-emitting layer, 7 is the D-A TADF material, 8 is the PbS quantum dot / D-A TADF contact depletion region, and 9 is the undepleted region of the PbS quantum dot.

[0040] 6) 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 TADF / PbS quantum dot / TADF stacked heterojunction composite film layer, serving as the source and drain electrodes of the optically controlled TADF / PbS quantum dot / TADF stacked heterojunction 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 50 μm. Figure 4 Schematic diagram of the silicon / silicon dioxide substrate structure after coating with the TADF-PbS quantum dot-TADF material composite film layer and plating the 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 material heterojunction quantum well structure on the upper surface of the channel layer, 4 is the single PbS quantum dot structure in the middle of the channel layer, 5 is the single PbS quantum dot / D-A TADF material heterojunction quantum well structure on the lower surface of the channel layer, 6 is the stacked heterojunction quantum well composite light-emitting layer, 7 is the D-A TADF material, 8 is the PbS quantum dot / D-A TADF contact depletion region, 9 is the undepleted region of the PbS quantum dot, 10 is the source electrode, and 11 is the drain electrode.

[0041] 7) The polyamic acid solution is spin-coated onto the silicon / silicon dioxide sample that has been prepared with the TADF / PbS quantum dot / TADF stacked heterojunction composite film layer and plated with electrodes at a rotation speed of 3000 rpm and a spin-coating time of 60 s, and then subjected to corresponding heat treatment for imidization, that is, an organic insulating encapsulation protection layer is formed on the TADF / PbS quantum dot / TADF stacked heterojunction composite film. Figure 5Schematic diagram of the structure of a light-controlled thin-film transistor with a composite structure of a stacked heterojunction of TADF-PbS quantum dots and TADF materials after encapsulation. Among them, 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 material heterojunction quantum well structure on the upper surface of the channel layer, 4 is a single PbS quantum dot structure in the middle of the channel layer, 5 is a single PbS quantum dot / D-A TADF material heterojunction quantum well structure on the lower surface of the channel layer, 6 is a stacked heterojunction quantum well composite light-emitting layer, 7 is the D-A TADF material, 8 is the PbS quantum dot / D-A TADF contact depletion region, 9 is the undepleted region of the PbS quantum dot, 10 is the source electrode, 11 is the drain electrode, and 12 is the organic insulation encapsulation layer. Figure 6 Schematic diagram of the working principle of a light-controlled thin-film transistor with a composite structure of a stacked heterojunction of TADF-PbS quantum dots and TADF materials. Among them, 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 material heterojunction quantum well structure on the upper surface of the channel layer, 4 is a single PbS quantum dot structure in the middle of the channel layer, 5 is a single PbS quantum dot / D-A TADF material heterojunction quantum well structure on the lower surface of the channel layer, 6 is a stacked heterojunction quantum well composite light-emitting layer, 7 is the D-A TADF material, 8 is the PbS quantum dot / D-A TADF contact depletion region, 9 is the undepleted region of the PbS quantum dot, 10 is the source electrode, 11 is the drain electrode, 12 is the organic insulation encapsulation layer, 13 is the direction of the irradiated light, and 14 is the TADF-PbS quantum dot-TADF material stacked heterojunction quantum well channel region whose conductivity is enhanced by light irradiation regulation.

[0042] As described 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 stacked heterojunction quantum well composite channel of a TADF / PbS quantum dot / TADF material, characterized in that, The method 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 TADF / PbS quantum dot / TADF material stacked heterojunction quantum well composite film layer 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 TADF / PbS quantum dot / TADF material stacked heterojunction quantum well composite film to obtain the source and drain electrodes of the light-controlled thin film transistor with a TADF / PbS quantum dot / TADF material stacked heterojunction quantum well composite structure; Step S4: Use organic encapsulation to fabricate a thin film transistor based on a light-controlled TADF / PbS quantum dot / TADF material stacked heterojunction quantum well composite conductive channel, and use light illumination to control the carrier concentration of the conductive channel.

2. The method for fabricating a light-controlled thin-film transistor based on a stacked heterojunction quantum well composite channel of a TADF / PbS quantum dot / TADF material according to claim 1, wherein The specific steps of step S2 include 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 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 a 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 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); Step S23: Prepare a TADF / PbS quantum dot / TADF material stacked heterojunction composite film layer: Clean the silicon / silicon dioxide substrate with a sulfuric acid / hydrogen peroxide solution at a high temperature, then wash it with deionized water 2-3 times, and use a spin coating process to spin coat a D-A TADF material film on the cleaned silicon / silicon dioxide substrate with the D-A TADF material solution prepared in step S22; use a spin coating process to spin coat a PbS quantum dot film on the silicon / silicon dioxide substrate sample that has been spin coated with a D-A TADF material film with the PbS quantum dot solution prepared in step S21; use a spin coating process to continue spin coating a D-A TADF film on the silicon / silicon dioxide substrate sample that has been spin coated with a D-A TADF / PbS quantum dot composite film with the D-A TADF material solution prepared in step S22 to form a TADF / PbS quantum dot / TADF material stacked heterojunction composite film layer on the surface of the silicon dioxide film, and obtain a silicon / silicon dioxide substrate covered with a TADF / PbS quantum dot / TADF material stacked heterojunction composite film layer.

3. The method for preparing a light-controlled thin film transistor based on a stacked heterojunction quantum well composite channel of a TADF / PbS quantum dot / TADF material according to claim 2, characterized in that, In the step S21, in the lead precursor solution, the amount of substance 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 substance 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 it is quickly cooled by means of a water bath and diluted with n-hexane to obtain a 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 centrifuged at 6000 - 8000 rpm for 5 - 10 min, and then the quantum dots are dissolved with n-hexane. The above cleaning process is repeated twice.

4. The method for preparing a light-controlled thin-film transistor based on a stacked heterojunction quantum well composite channel of a TADF / PbS quantum dot / 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 method for preparing a light-controlled thin-film transistor based on a stacked heterojunction quantum well composite channel of a TADF / PbS quantum dot / TADF material according to claim 2, wherein The concentration of the prepared PbS quantum dot solution is 10 - 30 mg / ml; the TADF / PbS quantum dot / 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 optically controlled thin-film transistor based on the stacked heterojunction quantum well composite channel of the TADF / PbS quantum dot / TADF material 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 first and second TADF film-forming processes, the concentration of the D-A TADF material solution is 15 - 40 mg / ml, 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; in the PbS quantum dot film-forming process, the concentration of the PbS quantum dot solution is 10 - 25 mg / ml, 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 preparation method of the optically controlled thin-film transistor based on the stacked heterojunction quantum well composite channel of TADF / PbS quantum dots / TADF material according to claim 1, characterized in that, The specific method of the step S3 is as follows: A Cr / Au composite metal electrode is formed on the silicon / silicon dioxide substrate covered with the TADF / PbS quantum dot / TADF material stacked heterojunction composite layer by using a patterned mask covering evaporation process, which are respectively used as the source electrode and the drain electrode of the optically controlled thin-film transistor of the TADF / PbS quantum dot / TADF material stacked heterojunction quantum well composite structure.

8. The method for preparing a light-controlled thin-film transistor based on a stacked heterojunction quantum well composite channel of a TADF / PbS quantum dot / 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 a TADF / PbS quantum dot / TADF material stacked heterojunction composite film layer by using a patterned metal mask, and then evaporation is carried out 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 method for preparing a light-controlled thin-film transistor based on a stacked heterojunction quantum well composite channel of a TADF / PbS quantum dot / TADF material according to claim 1, characterized in that The specific method of the 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 the TADF / PbS quantum dot / TADF material stacked heterojunction quantum well composite film layer to form a film, and a stepwise temperature heat treatment method is used to realize the imidization of the polyamic acid, so as to obtain an optically controlled thin-film transistor based on the TADF / PbS quantum dot / TADF material stacked heterojunction quantum well composite channel.

10. The method for preparing a light-controlled thin-film transistor based on a stacked heterojunction quantum well composite channel of a TADF / PbS quantum dot / TADF material according to claim 9, wherein, The step temperature heat treatment method is as follows: 120°C / 1h, 180°C / 1h, 250°C / 1h, 300°C / 1h.

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