Ultraviolet-assisted QWLED device based on CdZnS-PbS multiple composite deep well structure

Abstract

The invention provides an ultraviolet-assisted QWLED device based on a CdZnS-PbS multi-composite deep well structure. The ultraviolet-assisted QWLED device sequentially comprises an electrode, an inorganic electron transport layer, a laminated heterojunction deep quantum well light-emitting layer, an organic hole transport layer and an ITO glass substrate from top to bottom, the laminated heterojunction multiple deep quantum well light-emitting layer is of a five-layer structure formed by alternately stacking CdZnS quantum dot layers and PbS quantum dot layers twice, wherein CdZnS quantum dots are synthesized through an ultraviolet lamp excitation auxiliary thermal injection method. The lattice matching performance of the CdZnS quantum dots is regulated and controlled through ultraviolet light, and the CdZnS quantum dots and PbS form multiple depletion region heterojunctions.

Description

Technical Field

[0001] The present invention belongs to the technical fields of high-resolution display devices and nanophotonics, and particularly relates to a UV-assisted QWLED device based on a CdZnS-PbS multiple composite deep well structure. Background Art

[0002] Quantum dots, as quasi-zero-dimensional materials with all three-dimensional scales in the range of 1 to 100 nm, can control the quantum dot size, shape, and emission wavelength by adjusting parameters such as quantum dot growth time, reaction temperature, and ligands. Lead sulfide quantum dots, as a type of P-type semiconductor nanomaterial, have an adjustable bandgap (0.7–2.1 eV) and are an excellent choice for wavelength-tunable quantum dot devices due to their low cost, solution processability, and adjustable bandgap. Lead sulfide quantum dots are considered an excellent choice for applications such as near-infrared light-emitting LEDs and solar cells due to their relatively large size. However, there is still room for expansion in the research on lead sulfide quantum dots within the visible light excitation wavelength range.

[0003] To address the surface defects of lead sulfide quantum dot materials and increase the probability of forming effective composite excitons in the light-emitting layer, researchers have been seeking effective methods to passivate defects and further improve their optoelectronic properties. Some studies have shown that on the one hand, by forming a core-shell structure and strictly controlling the temperature and precursor concentration during the synthesis of the quantum dot core-shell structure, the lattice mismatch can be greatly reduced. On the other hand, a stacked multiple composite material can be formed by combining lead sulfide quantum dots with other quantum dots to regulate the energy band structure at the contact interface between the quantum dots, thereby improving their optoelectronic properties. (CN114447237A) provides a quantum dot light-emitting diode based on lead-based quantum dots and block polymers coated on the surface of the lead-based quantum dots, and its preparation method: the lead-based quantum dots are lead sulfide, lead selenide, and lead telluride; the block polymers are one or more of polystyrene-poly(4-vinylpyrimidine), poly(4-methylstyrene)-poly(4-vinylpyrimidine), and poly(3-methylstyrene)-poly(4-vinylpyrimidine). These block polymers are mainly used to repair the surface defects of lead-based quantum dots to improve the optoelectronic properties of the quantum dots. (CN114933898A) reports a preparation method of transition metal element-doped lead sulfide quantum dots: first, synthesize an organolead precursor doped with transition metal ions, and obtain a stock solution of lead sulfide colloidal quantum dots doped with transition metals by thermal injection method. After centrifugation and purification, lead sulfide colloidal quantum dots doped with transition metal elements are obtained. These lead sulfide quantum dots doped with transition metal elements can effectively reduce the surface defect rate of the quantum dots and improve the optoelectronic properties of the quantum dots. (CN103525416A) provides a green semiconductor nanocrystal for blue-light-excited LEDs and its preparation method: ZnS / PbS / ZnS quantum wells are synthesized by aqueous-phase synthesis method, which can emit green light under the excitation of light with a wavelength of 450-460 nm, and the emission spectrum range is 505-550 nm, effectively improving the photoluminescence performance of lead sulfide quantum dots. However, due to the poor lattice matching between ZnS and PbS in this quantum well material and the difficulty in forming ZnS crystal nuclei, the obtained quantum well material has poor consistency. (CN118579830A) discloses a PbS quantum dot-SnS2 heterostructure material, its preparation method and application: this heterojunction is composed of flower-like SnS2 nanosheets and PbS quantum dots, which is mainly used in the gas-sensing field, and its optoelectronic applications are limited.In addition, the luminescence performance of quantum dot light-emitting diodes ultimately depends on the charge distribution and performance of the quantum dot light-emitting layer, and is directly related to characteristics such as the carrier concentration in the light-emitting layer. Generally speaking, the higher the carrier concentration, the shorter the lifetime of photogenerated carriers or electrogenerated carriers in the semiconductor, the higher the probability of Auger recombination, and the lower the probability of forming effective photoelectric recombination exciton pairs, which is more unfavorable to the semiconductor luminescence performance. Under normal circumstances, the effective photoelectric effect of a diode usually occurs in the depletion region. This stacked heterojunction multiple deep quantum well composite light-emitting layer with stacked multiple depletion regions formed by means of stacked heterojunctions has a simple preparation process and can effectively exert the synergistic effect of the energy bands of each component in the stacked interface material and the conductive properties of the material, thereby achieving an improvement in the overall photoelectric performance of the stacked multiple heterojunctions.

[0004] In summary, at present, most of the lead sulfide quantum dot materials and devices mentioned in literature or patents cannot effectively passivate surface defects or form an effective composite light-emitting layer in theory, thus affecting the application of lead sulfide quantum dot materials in electroluminescence. Summary of the invention

[0005] In view of the defects and shortcomings of the prior art, the present invention provides a UV-assisted QWLED device based on a CdZnS-PbS multiple composite deep well structure and a preparation method thereof, wherein CdZnS quantum dots are synthesized by UV excitation-assisted hot injection method, and a CdZnS-PbS-CdZnS-PbS-CdZnS five-layer alternating stacked heterojunction multiple deep quantum well structure is sequentially deposited in combination with a spin coating process. The core innovations include: UV-assisted synthesis and structure design: Ultraviolet light (wavelength 365nm, irradiation for 2 minutes) regulates the lattice matching of CdZnS quantum dots, and zinc doping is combined to optimize the alloying properties; The five-layer alternating structure (CdZnS-PbS repeated twice) forms multiple depletion regions and heterojunction deep quantum wells parallel to the interface, enhancing the carrier confinement effect; Interface passivation and performance improvement: The coverage and modification of PbS surface by CdZnS quantum dots reduces interface defects, inhibits exciton quenching, and improves photoluminescence and electroluminescence efficiency; The stacked heterojunction multiple deep quantum well structure combines high quantum efficiency, optical properties and structural stability; Process controllability: CdZnS quantum dots were synthesized by hot injection and deposited layer by layer by spin coating (solution concentration 10-30 mg / ml), with annealing temperature (60-90°C) matching the interface thermal stability requirements; Inorganic electron transport layer (Zn 0.85 Mg 0.15O) The low-temperature annealing process (100 - 200 °C) of the organic hole transport layer (TFB / PEDOT:PSS) ensures the device integrity; Application potential: The prepared LED devices have excellent electroluminescence efficiency and external quantum efficiency, and have application prospects in the fields of high brightness, long life and high resolution display technologies.

[0006] The technical solutions specifically adopted by the present invention to solve its technical problems are as follows: A UV-assisted QWLED device based on a CdZnS-PbS multiple composite deep well structure, which successively includes an electrode, an inorganic electron transport layer, a stacked heterojunction deep quantum well light-emitting layer, an organic hole transport layer and an ITO glass substrate from top to bottom; The stacked heterojunction multiple deep quantum well light-emitting layer is formed by alternately stacking a CdZnS quantum dot layer and a PbS quantum dot layer twice to form a five-layer structure, wherein the CdZnS quantum dots are synthesized by an ultraviolet lamp-excited assisted thermal injection method; The CdZnS quantum dots regulate the lattice matching by ultraviolet light and form a multiple depletion region heterojunction with PbS.

[0007] Among them, the ultraviolet-excited assisted synthesis process (365 nm wavelength, 2-minute irradiation) and the five-layer alternating structure (CdZnS-PbS repeated twice) of the CdZnS quantum dots are to regulate the lattice matching of the CdZnS quantum dots by ultraviolet light (zinc doping concentration 2 - 5 mmol), and use the multiple depletion regions to enhance the carrier confinement effect. Ultraviolet excitation can reduce the size deviation of the CdZnS quantum dots (±0.5 nm), and the five-layer structure expands the exciton recombination region to the entire light-emitting layer through the energy band gradient design.

[0008] Further, the inorganic electron transport layer is a Zn 0.85 Mg 0.15 O electron transport layer; the organic hole transport layer includes a TFB hole transport layer and a PEDOT:PSS hole transport layer.

[0009] Further, the zinc doping concentration of the CdZnS quantum dots is 2 - 5 mmol, the annealing temperature is 60 - 90 °C, and the annealing time is 10 - 30 min.

[0010] The ultraviolet-assisted thermal injection method and the zinc doping concentration (2 - 5 mmol) ensure the lattice matching of the CdZnS quantum dots. The annealing parameters (60 - 90 °C, 10 - 30 min) ensure the interface stability and avoid the thermal decomposition of the quantum dots.

[0011] Further, the CdZnS quantum dot layer is formed by a CdZnS quantum dot solution with a concentration of 10 - 30 mg / ml. The preparation of the CdZnS quantum dot solution includes the following steps: (1a) Prepare a sulfur precursor: Mix 0.5 - 1 mmol of sulfur powder with 1 - 3 ml of trioctylphosphine, and stir and dissolve at 40 - 80 °C; (1b) Prepare a cadmium - zinc precursor: Mix 0.3 - 0.5 mmol of cadmium oxide, 2 - 5 mmol of zinc acetate, 4 - 8 ml of oleic acid, and 10 - 20 ml of octadecene, degas with nitrogen at 120 - 160 °C for 30 minutes, and then stir under vacuum for 2 hours; (1c) Inject the sulfur precursor solution in step (1a) into the cadmium - zinc precursor solution in step (1b), react at 290 - 310 °C for 8 - 10 minutes, and irradiate with a UV lamp with a wavelength of 365 nm for 2 minutes 2 minutes after the start of the reaction; (1d) Mix the mixed solution in step (1c) with methanol at a volume ratio of 2:1 to 1:1, centrifuge, add n - hexane to dissolve the precipitate, and obtain a purified CdZnS quantum dot solution.

[0012] Through the precise ratio of the sulfur precursor and the cadmium - zinc precursor combined with UV excitation, it is beneficial to control the uniformity of the quantum dot size (±0.5 nm) and reduce lattice defects. The cleaning process (methanol / n - hexane) ensures the purity of the quantum dots and is suitable for spin - coating into a film.

[0013] Further, the PbS quantum dot layer is formed by a PbS quantum dot solution with a concentration of 10 - 30 mg / ml. The preparation of the PbS quantum dot solution includes the following steps: (2a) Prepare a lead precursor: Mix 0.4 - 0.6 mmol of lead oxide, 1.0 - 1.2 ml of oleic acid, and 8 - 10 ml of octadecene, stir and dissolve at 120 - 150 °C, and then heat up to 270 - 300 °C; (2b) Prepare a sulfur precursor: Dissolve 0.50 - 0.75 mmol of sulfur powder in 1.40 - 1.70 ml of trioctylphosphine, inject it into the lead precursor solution in step (2a) at a rate of 1.0 - 2.0 ml / h, and cool in a water bath after reacting for 8 - 10 minutes; (2c) Mix the mixed solution in step (2b) with ethanol at a volume ratio of 2:1 to 1:1, centrifuge, add n - hexane to dissolve the precipitate, and dilute to 10 - 30 mg / ml.

[0014] Through precise control of the lead precursor (0.4 - 0.6 mmol of lead oxide) and the sulfur precursor (0.50 - 0.75 mmol of sulfur powder), the size of PbS quantum dots (5 - 10 nm) is ensured. The monodispersity of the quantum dots is optimized by low-speed injection (1.0 - 2.0 ml / h) to meet the interface quality requirements of the five-layer stacked structure.

[0015] Furthermore, the stacked heterojunction multiple deep quantum well light-emitting layer sequentially includes: The first CdZnS quantum dot layer, with a thickness of 3 - 8 nm; The first PbS quantum dot layer, with a thickness of 5 - 10 nm; The second CdZnS quantum dot layer, with a thickness of 3 - 8 nm; The second PbS quantum dot layer, with a thickness of 5 - 10 nm; The third CdZnS quantum dot layer, with a thickness of 3 - 8 nm.

[0016] The above thicknesses of the CdZnS layer (3 - 8 nm) and the PbS layer (5 - 10 nm) form a stepped energy band arrangement, enhancing the exciton recombination probability and avoiding being too thin (carrier leakage) or too thick (optical absorption loss).

[0017] Furthermore, the excitation conditions of the ultraviolet lamp are a wavelength of 365 nm and an irradiation time of 2 minutes, which are used to regulate the lattice matching and size uniformity of the CdZnS quantum dots.

[0018] The ultraviolet wavelength of 365 nm and the irradiation time of 2 minutes are used to optimize the lattice matching of the CdZnS quantum dots and ensure the interface compactness of the five-layer structure, reducing non-radiative recombination losses.

[0019] Furthermore, the inorganic electron transport layer is formed by spin-coating a Zn 0.85 Mg 0.15 O solution with a concentration of 15 - 25 mg / ml and annealed at 100 - 120 °C for 10 - 20 minutes.

[0020] Furthermore, the TFB layer is formed by spin-coating a TFB toluene solution with a concentration of 8 - 10 mg / ml and annealed at 160 - 200 °C for 15 - 30 minutes.

[0021] Furthermore, the PEDOT:PSS layer is formed by spin-coating a PEDOT:PSS solution filtered through a 0.22 - 0.45 μm pore size and annealed at 100 - 120 °C for 20 - 30 minutes.

[0022] Furthermore, the ITO glass substrate is pretreated by the following steps: (3a) Sequentially ultrasonic clean with deionized water, acetone, and isopropanol for 15 - 25 minutes; (3b) Dry it under nitrogen protection at 60 - 80 °C for 30 - 60 minutes to remove residual surface solvents and prevent oxidation.

[0023] Further, the electrode is a silver electrode with a thickness of 80 - 120 nm, formed by a thermal evaporation process.

[0024] Compared with the prior art, the present invention and its preferred embodiments have at least the following beneficial effects: 1. The ultraviolet-assisted synthesis process optimizes the performance of quantum dots Improved lattice matching: The lattice growth of CdZnS quantum dots is regulated by ultraviolet light (wavelength 365 nm, irradiated for 2 minutes), reducing the lattice mismatch rate with PbS quantum dots; Size uniformity: The size deviation of CdZnS quantum dots is controlled within ±0.5 nm, reducing the density of interface defects.

[0025] 2. The five-layer alternating structure enhances carrier confinement and recombination efficiency Multi-depletion region design: The CdZnS-PbS five-layer alternating structure (CdZnS 3 - 8 nm / PbS 5 - 10 nm) forms a stepped energy band arrangement, expanding the carrier recombination region; Improved external quantum efficiency: Significantly improved compared with traditional single-layer quantum dot devices.

[0026] 3. Interface coverage and defect passivation CdZnS quantum dot coverage and modification: The coverage of PbS surface by CdZnS quantum dots reduces interface defects and inhibits exciton quenching; Energy band bending and wave function overlap: The energy band bending of the heterojunction enhances the electron-hole recombination efficiency.

[0027] 4. Device stability and brightness improvement Extended working life: The device maintains high brightness stability after continuous operation; High brightness output: The brightness of the device is significantly higher than that of traditional structures.

[0028] 5. Wide spectral compatibility and application expansion Tunable emission wavelength: Visible to near-infrared emission is achieved by regulating the size of quantum dots; Flexible adaptability: Low annealing temperature is compatible with flexible substrates.

[0029] 6. Process controllability and mass production potential Precise control of solution concentration: The solution concentrations of CdZnS and PbS quantum dots are 10 - 30 mg / ml; Solvent adaptability: The n-hexane dilution process ensures film formation quality. Description of the Drawings

[0030] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments: Figure 1 It is a structural diagram of a single CdZnS quantum dot, a PbS quantum dot, a CdZnS / PbS / CdZnS / PbS / CdZnS heterojunction quantum well and a stacked heterojunction multiple deep quantum well composite light-emitting layer in an embodiment of the present invention; Figure 2 It is a structural diagram of an LED of a CdZnS / PbS / CdZnS / PbS / CdZnS stacked heterojunction multiple deep quantum well material in an embodiment of the present invention; Among them: 1 is a single CdZnS quantum dot in the depletion region, 2 is a single CdZnS quantum dot, 3 is a single PbS quantum dot, 4 is a single PbS quantum dot in the depletion region, 5 is a stacked heterojunction multiple deep quantum well composite light-emitting layer, 6 is the neutral region of the CdZnS quantum dot material, 7 is the contact depletion region of the CdZnS quantum dot, 8 is the CdZnS quantum dot at a non-interface, 9 is the neutral region of the PbS quantum dot material, 10 is the contact depletion region of the PbS quantum dot, 11 is the PbS quantum dot at a non-interface, 12 is a silver electrode, 13 is Zn 0.85 Mg 0.15 O electron transport layer, 14 is a CdZnS / PbS / CdZnS / PbS / CdZnS quantum dot stacked heterojunction multiple deep quantum well composite light-emitting layer, 15 is a TFB hole transport layer, 16 is a PEDOT:PSS hole transport layer, 17 is an ITO glass substrate. Specific embodiments

[0031] To make the features and advantages of the present invention more obvious and understandable, specific embodiments are given below and described in detail as follows: It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used in this specification have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present application belongs.

[0032] 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 "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0033] The structure of a QWLED with a CdZnS / PbS / CdZnS / PbS / CdZnS stacked multiple deep well composite light-emitting layer includes, from top to bottom, an electrode, an inorganic electron transport layer, a stacked heterojunction multiple deep well light-emitting layer, an organic hole transport layer, and an ITO glass substrate. The stacked heterojunction multiple deep quantum well light-emitting layer is formed by CdZnS / PbS / CdZnS quantum dot materials to form a composite light-emitting layer with a stacked heterojunction multiple deep quantum well structure.

[0034] Further, its inorganic electron transport layer is a Zn 0.85 Mg 0.15 O electron transport layer.

[0035] Further, its organic hole transport layer includes a TFB hole transport layer and a PEDOT:PSS hole transport layer.

[0036] The typical preparation process of the QWLED device provided above includes the following steps: (1) Clean the ITO conductive glass with deionized water, acetone, and isopropanol for 15 - 25 min respectively, and dry it with nitrogen at a certain temperature; (2) Spin-coat the PEDOT:PSS solution on the ITO conductive glass in step (1) with a spin coater in a glove box, and then put the conductive glass sheet on a heating table for annealing; (3) Dissolve TFB in toluene solution, and then spin-coat the solution on the conductive glass sheet in step (2) with a spin coater in a glove box, and then put the conductive glass sheet on a heating table for annealing; (4) Spin-coat the CdZnS quantum dot solution on the conductive glass sample in step (3) with a spin coater in a glove box, and then put the conductive glass sample on a heating table for annealing; (5) Spin-coat the PbS quantum dot solution on the conductive glass sample in step (4) with a spin coater in a glove box, and then put the conductive glass sample on a heating table for annealing; (6) Spin-coat the CdZnS quantum dot solution on the conductive glass sample in step (5) with a spin coater in a glove box, and then put the conductive glass sample on a heating table for annealing; (7) Spin-coat the PbS quantum dot solution on the conductive glass sample in step (6) with a spin coater in a glove box, and then put the conductive glass sample on a heating table for annealing; (8) Spin-coat the CdZnS quantum dot solution on the conductive glass sample in step (7) with a spin coater in a glove box, and then put the conductive glass sample on a heating table for annealing; (9) In the glove box, Zn 0.85 Mg 0.15The O solution was spin-coated on the conductive glass sample in step (8) using a spin coater, and then the conductive glass sheet was placed on a heating stage for annealing. (10)The conductive glass sample obtained in step (9) was used to deposit electrodes by thermal evaporation, and a QWLED with a CdZnS / PbS / CdZnS / PbS / CdZnS stacked multiple deep well composite light-emitting layer was obtained.

[0037] Furthermore, in step (2), the PEDOT:PSS solution was first filtered through a 0.22 - 0.45 μm filter head, the annealing temperature was 100 - 120 °C, the environmental condition was in a glove box with a nitrogen atmosphere where both oxygen and water were less than 1 ppm, and the annealing time was 20 - 30 min.

[0038] Furthermore, the concentration of its TFB solution was 8 - 10 mg / ml, the annealing temperature was 160 - 200 °C, the environmental condition was in a glove box with a nitrogen atmosphere where both oxygen and water were less than 1 ppm, and the annealing time was 15 - 30 min.

[0039] Furthermore, the specific method for preparing CdZnS quantum dots in steps (4), (6), and (8) was as follows: A certain amount of sulfur powder and TOP solution were stirred and dissolved at a set temperature to prepare a sulfur precursor solution; a certain amount of cadmium oxide, zinc acetate, and oleic acid were stirred for a set time at a set temperature, then a small amount of ODE solution was injected, and the solution temperature was raised; the sulfur precursor solution was taken and quickly injected into the cadmium-zinc solution when the solution temperature reached the set value and kept for a set time, while being excited by an ultraviolet lamp; finally, the quantum dot solution was quickly cooled by a water bath, diluted with n-hexane, and the quantum dot solution was obtained and stored under low-temperature conditions; a part of the supernatant of the quantum dot solution after standing was taken, the oleic acid was dissolved with an appropriate amount of methanol, then an appropriate amount of n-hexane solution was added and the upper layer solution was taken out, an appropriate amount of absolute ethanol was added for centrifugation, and finally the precipitate was dissolved with n-hexane to obtain a purified quantum dot solution.

[0040] Furthermore, the specific method for preparing PbS quantum dots in steps (5) and (7) was as follows: A certain amount of lead oxide, oleic acid, and octadecene were dissolved at a set temperature to prepare a lead precursor solution; a certain amount of sulfur powder was dissolved in trioctylphosphine and injected into a three-necked flask at a certain speed, and finally the quantum dot solution was quickly cooled by a water bath, diluted with n-hexane, and the quantum dot solution was obtained and stored under low-temperature conditions; a part of the supernatant of the quantum dot solution after standing was taken, dissolved with an appropriate amount of ethanol, then an appropriate amount of n-hexane solution was added and the upper layer solution was taken out, an appropriate amount of absolute ethanol was added for centrifugation, and finally the precipitate was dissolved with n-hexane to obtain a purified quantum dot solution.

[0041] Further, in the sulfur precursor solution, the amount of sulfur powder is 0.5 - 1 mmol, TOP is 1 - 3 ml, the stirring temperature is 40 - 80 °C, and the stirring time is 10 - 30 minutes to obtain the sulfur precursor solution; in the cadmium-zinc precursor solution, the amount of cadmium oxide is 0.3 - 0.5 mmol, the amount of zinc acetate is 2 - 5 mmol, the amount of oleic acid is 4 - 8 ml, the amount of ODE is 10 - 20 ml. After degassing for 30 minutes under nitrogen at 120 - 160 °C, and stirring under vacuum for 2 hours to obtain a transparent cadmium-zinc precursor solution, then introducing nitrogen and raising the temperature to 290 - 310 °C; subsequently, quickly injecting the sulfur precursor solution into the cadmium-zinc precursor solution, maintaining for 8 - 10 min, and exciting with an ultraviolet lamp at 2 min; in the quantum dot cleaning, the ratio of the quantum dot supernatant to methanol is 2:1 - 1:1. Dissolve the precipitate in n-hexane, extract the upper layer solution, add an excess of absolute ethanol and centrifuge at 6000 - 8000 rpm for 5 - 10 min, and then dissolve the quantum dots in n-hexane, repeating the above cleaning process twice.

[0042] Further, 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, and after dissolution, raise the temperature to 270 - 300 °C; in the sulfur precursor solution, 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, and after dissolution, inject it into the lead precursor three-necked flask at a rate of 1.0 - 2.0 ml / h, maintaining for 8 - 10 min; in the quantum dot cleaning, the ratio of the quantum dot supernatant to methanol is 2:1 - 1:1. Dissolve the precipitate in n-hexane, extract the upper layer solution, add an excess of absolute ethanol and centrifuge at 6000 - 8000 rpm for 5 - 10 min, and then dissolve the quantum dots in n-hexane, repeating the above cleaning process twice.

[0043] Further, the concentration of the finally prepared CdZnS quantum dot solution is 10 - 30 mg / ml.

[0044] Further, the concentration of the finally prepared PbS quantum dot solution is 10 - 30 mg / ml.

[0045] Further, in steps (4), (6) and (8), the concentration of the CdZnS quantum dot solution is 10 - 30 mg / ml, 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.

[0046] Further, the concentration of the PbS quantum dot solution described in steps (5) and (7) is 10 - 30 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.

[0047] Further, the concentration of the Zn 0.85 Mg 0.15 O solution described in step (9) is 15 - 25 mg / ml, the annealing temperature is 100 - 120 °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 - 20 min.

[0048] Further, the electrode described in step (10) is a silver electrode with a thickness of 100 nm.

[0049] The following further provides 3 specific preferred preparation examples to further demonstrate this solution: Example 1 1) Put the ITO glass into a beaker, pour in acetone solution, isopropyl alcohol solution and deionized water solution in sequence, and ultrasonically clean each for 25 min. Take it out, dry it with nitrogen at 60 °C, and put it into a clean and dry petri dish.

[0050] 2) After filtering the PEDOT:PSS solution with a 0.45 μm filter head, spin - coat it on the ITO glass at a low speed of 500 rpm / s for 5 s and a high speed of 3000 rpm / s for 40 s using a spin coater. Then put the glass slide on a heating table and anneal it at 120 °C for 30 min.

[0051] 3) Take 10 mg of TFB and 1 ml of toluene solution. After dissolving TFB in toluene to prepare a solution with a concentration of 10 mg / mL, spin - coat it on the glass slide at a low speed of 500 rpm / s for 5 s and a high speed of 2000 rpm / s for 40 s using a spin coater. Then put the glass slide on a heating table and anneal it at 200 °C for 30 min.

[0052] 4) Preparation of CdZnS quantum dots: Add 1 mmol of sulfur powder and 3 ml of TOP solution into a three-necked flask, stir at 80 °C for 30 minutes to dissolve it, and prepare a sulfur precursor solution; add 0.5 mmol of cadmium oxide, 5 mmol of zinc acetate and 8 ml of oleic acid, stir at 150 °C for 30 min, then inject 20 ml of ODE solution, degas under nitrogen at 160 °C for 30 minutes, and stir under vacuum for 2 hours to obtain a transparent cadmium-zinc precursor solution. Subsequently, introduce nitrogen and raise the temperature to 310 °C; take the selenium precursor solution, quickly inject it into the cadmium-zinc precursor solution when the temperature of the cadmium-zinc precursor solution reaches 310 °C and keep it for 10 min. At the same time, use an ultraviolet lamp to excite at 2 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 quantum dot solution, the ratio of the quantum dot supernatant to methanol is 2:1, dissolve the precipitate in n-hexane, extract the upper layer solution, add an excessive amount of absolute ethanol and centrifuge at 8000 rpm for 10 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 30 mg / ml quantum dot solution, and store it under low temperature conditions.

[0053] 5) 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 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, then inject it into the three-necked flask of the lead precursor at a speed 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 quantum dot solution, the ratio of the quantum dot supernatant to methanol is 2:1, dissolve the precipitate in n-hexane, extract the upper layer solution, add an excessive amount of absolute ethanol and centrifuge at 8000 rpm for 10 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 30 mg / ml quantum dot solution, and store it under low temperature conditions.

[0054] 6) Dilute the CdZnS quantum dot colloidal solution to 30 mg / ml with n-octane, 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 with a spin coater, and then anneal the above glass slide on a heating table at 90 °C for 30 min.

[0055] 7) Dilute the PbS quantum dot colloidal solution with n-octane to a 30 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 above glass slide on a heating table and anneal it at 90 °C for 30 min.

[0056] 8) Dilute the CdZnS quantum dot colloidal solution with n-octane to 30 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 above glass slide on a heating table and anneal it at 90 °C for 30 min.

[0057] 9) Dilute the PbS quantum dot colloidal solution with n-octane to a 30 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 above glass slide on a heating table and anneal it at 90 °C for 30 min.

[0058] 10) Dilute the CdZnS quantum dot colloidal solution with n-octane to 30 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 above glass slide on a heating table and anneal it at 90 °C for 30 min. Figure 1 It is a structural diagram of a composite light-emitting layer of a single CdZnS quantum dot, a PbS quantum dot, and its CdZnS / PbS / CdZnS / PbS / CdZnS heterojunction quantum well and its stacked heterojunction multiple deep quantum wells; where 1 is a single CdZnS quantum dot in the depletion region, 2 is a single CdZnS quantum dot, 3 is a single PbS quantum dot, 4 is a single PbS quantum dot in the depletion region, 5 is a stacked heterojunction multiple deep quantum well composite light-emitting layer, 6 is the neutral region of the CdZnS quantum dot material, 7 is the contact depletion region of the CdZnS quantum dot, 8 is the CdZnS quantum dot at a non-interface, 9 is the neutral region of the PbS quantum dot material, 10 is the contact depletion region of the PbS quantum dot, and 11 is the PbS quantum dot at a non-interface.

[0059] 11) Take a Zn 0.85 Mg 0.15 O solution with a concentration of 25 mg / ml, spin-coat it at a low speed of 500 rpm / s for 5 s and a high speed of 1000 rpm / s for 40 s using a spin coater, and then place the glass slide in a heating table and anneal it at 120 °C for 20 min.

[0060] 12) Thermally evaporate a 100 nm silver electrode to obtain a QWLED with a CdZnS / PbS / CdZnS / PbS / CdZnS stacked heterojunction multiple deep quantum well composite light-emitting layer. Figure 2It is a structural diagram of an LED of a CdZnS / PbS / CdZnS / PbS / CdZnS stacked heterojunction multiple deep quantum well material; where 12 is a silver electrode and 13 is Zn 0.85 Mg 0.15 O electron transport layer, 14 is a CdZnS / PbS / CdZnS / PbS / CdZnS quantum dot stacked heterojunction multiple deep quantum well composite light-emitting layer, 15 is a TFB hole transport layer, 16 is a PEDOT:PSS hole transport layer, and 17 is an ITO glass substrate.

[0061] Example 2 1) Put the ITO glass into a beaker, pour acetone solution, isopropanol solution and deionized water solution in turn, and ultrasonically clean each for 20 min. Take it out, dry it with nitrogen at 60 °C, and put it into a clean and dry petri dish.

[0062] 2) After filtering the PEDOT:PSS solution with a 0.45 μm filter head, spin-coat it on the ITO glass at a low speed of 500 rpm / s for 5 s and a high speed of 3000 rpm / s for 40 s with a spin coater. Then put the glass slide on a heating table and anneal it at 110 °C for 25 min.

[0063] 3) Take 9 mg of TFB and 1 ml of toluene solution. After dissolving TFB in toluene to prepare a solution with a concentration of 9 mg / mL, spin-coat it on the glass slide at a low speed of 500 rpm / s for 5 s and a high speed of 2000 rpm / s for 40 s with a spin coater. Then put the glass slide on a heating table and anneal it at 180 °C for 20 min.

[0064] 4) Preparation of CdZnS quantum dots: Add 0.7 mmol of sulfur powder and 2 ml of TOP solution into a three-necked flask, stir at 60 °C for 20 minutes to dissolve it, and prepare a sulfur precursor solution; Stir 0.4 mmol of cadmium oxide, 4 mmol of zinc acetate and 6 ml of oleic acid at 140 °C for 30 min, then inject 15 ml of ODE solution, degas under nitrogen at 160 °C for 30 minutes, and stir under vacuum for 2 hours to obtain a transparent cadmium zinc precursor solution. Subsequently, introduce nitrogen and raise the temperature to 310 °C; Take the selenium precursor solution, quickly inject it into the cadmium zinc precursor solution when the temperature of the cadmium zinc precursor solution reaches 300 °C and keep it for 9 min. At the same time, use an ultraviolet lamp to excite at 2 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; Subsequently, take the quantum dot solution, the ratio of the quantum dot supernatant to methanol is 1.5:1, dissolve the precipitate in n-hexane, extract the upper layer solution, add an excessive amount of absolute ethanol and centrifuge at 7000 rpm for 7 min, then dissolve the quantum dot with n-hexane, repeat the above washing process twice, dissolve the quantum dot in n-hexane to form a 20 mg / ml quantum dot solution, and store it under low temperature conditions.

[0065] 5) 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 min, and raise the temperature to 285 °C after dissolution to prepare a lead precursor solution; Take 0.625 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 means of a water bath, dilute it with n-hexane to obtain a quantum dot solution; Subsequently, take the quantum dot solution, the ratio of the quantum dot supernatant to methanol is 1.5:1, dissolve the precipitate in n-hexane, extract the upper layer solution, add an excessive amount of absolute ethanol and centrifuge at 7000 rpm for 7 min, then dissolve the quantum dot with n-hexane, repeat the above washing process twice, dissolve the quantum dot in n-hexane to form a 20 mg / ml quantum dot solution, and store it under low temperature conditions.

[0066] 6) Dilute the CdZnS quantum dot colloidal solution to 20 mg / ml with n-octane, 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 with a spin coater, and then anneal the above glass slide on a heating table at 75 °C for 20 min.

[0067] 7) Dilute the PbS quantum dot colloidal solution with n-octane to a 20 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 above glass slide on a heating table and anneal it at 75 °C for 20 min.

[0068] 8) Dilute the CdZnS quantum dot colloidal solution with n-octane to 20 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 above glass slide on a heating table and anneal it at 75 °C for 20 min.

[0069] 9) Dilute the PbS quantum dot colloidal solution with n-octane to a 20 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 above glass slide on a heating table and anneal it at 75 °C for 20 min.

[0070] 10) Dilute the CdZnS quantum dot colloidal solution with n-octane to 20 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 above glass slide on a heating table and anneal it at 75 °C for 20 min. Figure 1 It is the structural diagram of a composite light-emitting layer of single CdZnS quantum dots, PbS quantum dots, and their CdZnS / PbS / CdZnS / PbS / CdZnS heterojunction quantum wells and stacked heterojunction multiple deep quantum wells; where 1 is a single CdZnS quantum dot in the depletion region, 2 is a single CdZnS quantum dot, 3 is a single PbS quantum dot, 4 is a single PbS quantum dot in the depletion region, 5 is a stacked heterojunction multiple deep quantum well composite light-emitting layer, 6 is the neutral region of the CdZnS quantum dot material, 7 is the contact depletion region of the CdZnS quantum dot, 8 is the CdZnS quantum dot at a non-interface, 9 is the neutral region of the PbS quantum dot material, 10 is the contact depletion region of the PbS quantum dot, and 11 is the PbS quantum dot at a non-interface.

[0071] 11) Take a Zn 0.85 Mg 0.15 O solution with a concentration of 20 mg / ml, spin-coat it at a low speed of 500 rpm / s for 5 s and a high speed of 1000 rpm / s for 40 s using a spin coater, and then place the glass slide in a heating table and anneal it at 110 °C for 15 min.

[0072] 12) Thermally evaporate a 100 nm silver electrode to obtain a QWLED with a CdZnS / PbS / CdZnS / PbS / CdZnS stacked heterojunction multiple deep quantum well composite light-emitting layer. Figure 2It is a structural diagram of an LED made of a CdZnS / PbS / CdZnS / PbS / CdZnS stacked heterojunction multiple deep quantum well material; among them, 12 is a silver electrode, and 13 is Zn 0.85 Mg 0.15 O electron transport layer, 14 is a CdZnS / PbS / CdZnS / PbS / CdZnS quantum dot stacked heterojunction multiple deep quantum well composite light-emitting layer, 15 is a TFB hole transport layer, 16 is a PEDOT:PSS hole transport layer, and 17 is an ITO glass substrate.

[0073] Example 3 1) Place the ITO glass in a beaker, pour in acetone solution, isopropanol solution, and deionized water solution in sequence, and ultrasonically clean each for 15 min. Take it out, dry it with nitrogen at 60 °C, and place it in a clean and dry petri dish.

[0074] 2) After filtering the PEDOT:PSS solution with a 0.22 μm filter head, spin-coat it on the ITO glass at a low speed of 500 rpm / s for 5 s and a high speed of 3000 rpm / s for 40 s using a spin coater. Then place the glass slide on a heating table and anneal it at 100 °C for 20 min.

[0075] 3) Take 8 mg of TFB and 1 ml of toluene solution. After dissolving TFB in toluene to prepare a solution with a concentration of 8 mg / mL, spin-coat it on the glass slide at a low speed of 500 rpm / s for 5 s and a high speed of 2000 rpm / s for 40 s using a spin coater. Then place the glass slide on a heating table and anneal it at 160 °C for 15 min.

[0076] 4) Preparation of CdZnS quantum dots: Add 0.5 mmol of sulfur powder and 1 ml of TOP solution into a three-necked flask, stir at 40 °C for 10 minutes to dissolve it, and prepare a sulfur precursor solution; add 0.3 mmol of cadmium oxide, 2 mmol of zinc acetate and 4 ml of oleic acid, stir at 120 °C for 30 min, then inject 10 ml of ODE solution, degas under nitrogen at 120 °C for 30 minutes, and stir under vacuum for 2 hours to obtain a transparent cadmium zinc precursor solution. Subsequently, introduce nitrogen and raise the temperature to 290 °C; take the sulfur precursor solution, quickly inject it into the cadmium zinc precursor solution when the temperature of the cadmium zinc precursor solution reaches 290 °C and keep it for 8 min. At the same time, use an ultraviolet lamp to excite at 2 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 quantum dot solution, the ratio of the quantum dot supernatant to methanol 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 dot with n-hexane, repeat the above cleaning process twice, dissolve the quantum dot in n-hexane to form a 10 mg / ml quantum dot solution, and store it under low temperature conditions.

[0077] 5) 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 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 trioctylphosphine, stir at 120 °C until completely dissolved, and then inject it into the three-necked flask of the lead precursor at a speed of 1.0 ml / h, and keep it for 8 min after injection; 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 quantum dot solution, the ratio of the quantum dot supernatant to methanol 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 dot with n-hexane, repeat the above cleaning process twice, dissolve the quantum dot in n-hexane to form a 10 mg / ml quantum dot solution, and store it under low temperature conditions.

[0078] 6) Dilute the CdZnS quantum dot colloidal solution with n-octane to 10 mg / ml, 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 with a spin coater, and then anneal the above glass slides on a heating table at 60 °C for 10 min.

[0079] 7) Dilute the PbS quantum dot colloidal solution with n-octane to a 10 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 above glass slide on a heating table and anneal it at 60 °C for 10 min.

[0080] 8) Dilute the CdZnS quantum dot colloidal solution with n-octane to 10 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 above glass slide on a heating table and anneal it at 60 °C for 10 min.

[0081] 9) Dilute the PbS quantum dot colloidal solution with n-octane to a 10 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 above glass slide on a heating table and anneal it at 60 °C for 10 min.

[0082] 10) Dilute the CdZnS quantum dot colloidal solution with n-octane to 10 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 above glass slide on a heating table and anneal it at 60 °C for 10 min. Figure 1 It is a structural diagram of a composite light-emitting layer of a single CdZnS quantum dot, a PbS quantum dot, and its CdZnS / PbS / CdZnS / PbS / CdZnS heterojunction quantum well and its stacked heterojunction multiple deep quantum wells; where 1 is a single CdZnS quantum dot in the depletion region, 2 is a single CdZnS quantum dot, 3 is a single PbS quantum dot, 4 is a single PbS quantum dot in the depletion region, 5 is a stacked heterojunction multiple deep quantum well composite light-emitting layer, 6 is the neutral region of the CdZnS quantum dot material, 7 is the contact depletion region of the CdZnS quantum dot, 8 is the CdZnS quantum dot at a non-interface, 9 is the neutral region of the PbS quantum dot material, 10 is the contact depletion region of the PbS quantum dot, and 11 is the PbS quantum dot at a non-interface.

[0083] 11) Take a Zn 0.85 Mg 0.15 O solution with a concentration of 15 mg / ml, spin-coat it at a low speed of 500 rpm / s for 5 s and a high speed of 1000 rpm / s for 40 s using a spin coater. Then place the glass slide in a heating table and anneal it at 100 °C for 10 min.

[0084] 12) Thermally evaporate a 100 nm silver electrode to obtain a QWLED with a CdZnS / PbS / CdZnS / PbS / CdZnS stacked heterojunction multiple deep quantum well composite light-emitting layer. Figure 2It is a structural diagram of an LED of a CdZnS / PbS / CdZnS / PbS / CdZnS stacked heterojunction multiple deep quantum well material; where 12 is a silver electrode and 13 is Zn 0.85 Mg 0.15 O electron transport layer, 14 is a CdZnS / PbS / CdZnS / PbS / CdZnS quantum dot stacked heterojunction multiple deep quantum well composite light-emitting layer, 15 is a TFB hole transport layer, 16 is a PEDOT:PSS hole transport layer, and 17 is an ITO glass substrate.

[0085] It should be noted that unless otherwise defined, the technical terms or scientific terms used in the present invention should have the ordinary meanings understood by those with ordinary skills in the field to which the present invention belongs. The "first", "second" and similar terms used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Words such as "including" or "comprising" mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connected" or "coupled" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right", etc. are only used to represent relative position relationships. When the absolute position of the object being described changes, the relative position relationship may also change accordingly.

[0086] The above are only the preferred embodiments of the present invention, and are not limitations on the present invention in other forms. Any person skilled in the art may use the technical content disclosed above to make changes or modifications into equivalent embodiments with equivalent changes. However, any simple modifications, equivalent changes and modifications 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.

[0087] The present invention is not limited to the above best mode. Anyone inspired by the present invention can obtain various other forms of ultraviolet-assisted QWLED devices based on the CdZnS-PbS multiple composite deep well structure. All equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the coverage of the present invention.

Claims

1. An ultraviolet-assisted QWLED device based on a CdZnS-PbS multiple composite deep well structure, characterized in that: It successively includes an electrode, an inorganic electron transport layer, a stacked heterojunction deep quantum well light-emitting layer, an organic hole transport layer, and an ITO glass substrate from top to bottom; The stacked heterojunction multiple deep quantum well light-emitting layer is formed by alternately stacking a CdZnS quantum dot layer and a PbS quantum dot layer twice to form a five-layer structure, where the CdZnS quantum dots are synthesized by an ultraviolet lamp-excited assisted thermal injection method; The CdZnS quantum dots regulate the lattice matching through ultraviolet light and form a multiple depletion region heterojunction with PbS.

2. The ultraviolet-assisted QWLED device based on the CdZnS-PbS multiple composite deep well structure according to claim 1, characterized in that: The inorganic electron transport layer is a Zn 0.85 Mg 0.15 O electron transport layer.

3. The ultraviolet-assisted QWLED device based on the CdZnS-PbS multiple composite deep well structure according to claim 1, wherein: The organic hole transport layer includes a TFB hole transport layer and a PEDOT:PSS hole transport layer.

4. The ultraviolet-assisted QWLED device based on the CdZnS-PbS multiple composite deep well structure according to claim 1, characterized in that: The zinc doping concentration of the CdZnS quantum dots is 2 - 5 mmol, the annealing temperature is 60 - 90 °C, and the annealing time is 10 - 30 min.

5. The ultraviolet-assisted QWLED device based on the CdZnS-PbS multiple composite deep well structure according to claim 1, characterized in that: The CdZnS quantum dot layer is formed by a CdZnS quantum dot solution with a concentration of 10 - 30 mg / ml, and the preparation of the CdZnS quantum dot solution includes the following steps: (1a) Prepare a sulfur precursor: Mix sulfur powder with a mass of 0.5 - 1 mmol and tri-n-octylphosphine with a volume of 1 - 3 ml, and stir and dissolve at 40 - 80 °C; (1b) Prepare a cadmium-zinc precursor: Mix cadmium oxide with a molar amount of 0.3 - 0.5 mmol, zinc acetate with a molar amount of 2 - 5 mmol, oleic acid with a volume of 4 - 8 ml, and octadecene with a volume of 10 - 20 ml, degas with nitrogen at 120 - 160 °C for 30 minutes, and then stir under vacuum for 2 hours; (1c) Inject the sulfur precursor solution in step (1a) into the cadmium-zinc precursor solution in step (1b), react at 290 - 310 °C for 8 - 10 minutes, and irradiate with an ultraviolet lamp with a wavelength of 365 nm for 2 minutes 2 minutes after the start of the reaction; (1d) Mix the mixed solution in step (1c) with methanol at a volume ratio of 2:1 to 1:1, centrifuge, and then add n-hexane to dissolve the precipitate to obtain a purified CdZnS quantum dot solution.

6. The ultraviolet-assisted QWLED device based on the CdZnS-PbS multiple composite deep well structure according to claim 1, characterized in that: The PbS quantum dot layer is formed by a PbS quantum dot solution with a concentration of 10 - 30 mg / ml, and the preparation of the PbS quantum dot solution includes the following steps: (2a) Prepare a lead precursor: Mix lead oxide with a molar amount of 0.4 - 0.6 mmol, oleic acid with a volume of 1.0 - 1.2 ml, and octadecene with a volume of 8 - 10 ml, stir and dissolve at 120 - 150 °C, and then heat up to 270 - 300 °C; (2b) Prepare a sulfur precursor: Dissolve sulfur powder with a molar amount of 0.50 - 0.75 mmol in tri-n-octylphosphine with a volume of 1.40 - 1.70 ml, and inject it into the lead precursor solution in step (2a) at a rate of 1.0 - 2.0 ml / h, and cool in a water bath after reacting for 8 - 10 minutes; (2c) Mix the mixed solution in step (2b) with ethanol at a volume ratio of 2:1 to 1:

1. After centrifugation, add n-hexane to dissolve the precipitate, and dilute it to 10 - 30 mg / ml.

7. The ultraviolet-assisted QWLED device based on the CdZnS-PbS multiple composite deep trap structure according to claim 1, wherein: The stacked heterojunction multiple deep quantum well light-emitting layer sequentially includes: The first CdZnS quantum dot layer with a thickness of 3 - 8 nm; The first PbS quantum dot layer with a thickness of 5 - 10 nm; The second CdZnS quantum dot layer with a thickness of 3 - 8 nm; The second PbS quantum dot layer with a thickness of 5 - 10 nm; The third CdZnS quantum dot layer with a thickness of 3 - 8 nm.

8. The ultraviolet-assisted QWLED device based on the CdZnS-PbS multiple composite deep well structure according to claim 1, characterized in that: The ultraviolet lamp excitation conditions are a wavelength of 365 nm and an irradiation time of 2 minutes, which are used to regulate the lattice matching and size uniformity of the CdZnS quantum dots.

9. The ultraviolet-assisted QWLED device based on the CdZnS-PbS multiple composite deep well structure according to claim 2, wherein: The inorganic electron transport layer is formed by spin-coating with a Zn 0.85 Mg 0.15 O solution with a concentration of 15-25 mg / ml and annealed at 100-120 °C for 10-20 minutes.

10. The ultraviolet-assisted QWLED device based on the CdZnS-PbS multiple composite deep well structure according to claim 3, characterized in that: The TFB layer is formed by spin-coating a TFB toluene solution with a concentration of 8 - 10 mg / ml and annealing it at 160 - 200 °C for 15 - 30 minutes; The PEDOT:PSS layer is formed by spin-coating a PEDOT:PSS solution filtered through a 0.22 - 0.45 μm pore size and annealing it at 100 - 120 °C for 20 - 30 minutes.

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