6OBA-doped perovskite quantum dot film and preparation method thereof

Abstract

The invention relates to the technical field of perovskite quantum dots, in particular to a 6OBA-doped perovskite quantum dot film and a preparation method thereof. Comprising the following steps: preparing a perovskite quantum dot precursor solution; the preparation method comprises the following steps: mixing 6OBA, lead bromide and octadecene, stirring in an argon atmosphere, heating to 115-125 DEG C, and continuing for 0.5-1.5 hours; mixing oleic acid and oleylamine, rapidly injecting by using an injector, and stirring until the mixture is completely dissolved; after the solution is clarified, heating to 175-185 DEG C, starting condensate water, and rapidly injecting a perovskite quantum dot precursor solution; after reacting for 0.5-2 minutes, quickly cooling with an ice-water bath, and terminating the reaction; washing, purifying and dispersing into an organic solvent to obtain quantum dot dispersion liquid; and carrying out spin coating on the quantum dot dispersion liquid to prepare the 6OBA doped perovskite quantum dot film. The method has the advantages that a stable coordination body is formed through 6OBA doping, the defects of the quantum dots are passivated, and the photoluminescence quantum efficiency of the quantum dots is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of perovskite quantum dots, and in particular to a 6OBA-doped perovskite quantum dot film and a preparation method thereof. Background Art

[0002] Semiconductor lasers have been favored by scientific researchers due to their unique advantages such as miniaturization, integration, high efficiency, long life, low energy consumption and rapid modulation. Semiconductor materials are an important material basis for the preparation of semiconductor lasers with high optoelectronic performance. Among many semiconductor materials, perovskite quantum dots stand out with their unique advantages. They have many excellent optoelectronic properties such as high photoluminescence quantum yield (PLQY), narrow half-width, high carrier mobility, etc. Through simple regulation of composition, size and dimension, the luminescence spectrum of the material can cover the entire visible light band, filling the spectral gap not covered by existing lasers. In addition, the solution processability enables the large-scale manufacture of devices at a low cost, which meets the current demand for semiconductor laser working materials and is a very promising laser gain material.

[0003] Compared to traditional semiconductors, perovskite crystals exhibit high defect tolerance due to the antibonding coupling of the perovskite lattice caused by the high ionicity of the bonding. Deep energy level defects can be located within the conduction band and the valence band. However, due to point defects on the surface of quantum dots or defects at the crystal grain boundaries, shallow energy level defects are present, which still require further passivation. Otherwise, excited excitons will be trapped in the defect state energy level between the conduction band and the valence band, and then undergo non-radiative recombination, resulting in a high laser threshold, which will limit the further development and application of perovskites.

[0004] Currently, commonly used passivating agents such as oleylamine and oleic acid can effectively reduce surface defects on quantum dots, thereby improving their optical properties and stability. However, they are easily detached from the surface of the quantum dots during the subsequent purification process, causing quantum dot agglomeration and even phase transitions, which degrades the optical properties of the quantum dots. Therefore, finding high-performance doping materials and preparing high-quality perovskite quantum dots are key scientific and technological challenges that need to be addressed in this field. Summary of the Invention

[0005] In order to solve the above problems, the present invention provides a 6OBA-doped perovskite quantum dot film and a preparation method thereof.

[0006] The first object of the present invention is to provide a method for preparing a 6OBA-doped perovskite quantum dot film, which specifically comprises the following steps: S1. Preparation of perovskite quantum dot precursor solution; S2. Preparation of 4-(6-(acryloyloxy)hexyloxy)benzoic acid-doped perovskite quantum dots; specifically comprising the following sub-steps: S201. Mix 4-(6-(acryloyloxy)hexyloxy)benzoic acid, lead bromide, and octadecene, stir under an argon atmosphere, heat to 115 - 125 °C and continue for 0.5 - 1.5 hours; S202. Mix oleic acid and oleylamine, quickly inject them into the reaction flask with a syringe, continue stirring until completely dissolved; after the solution becomes clear, heat to 175 - 185 °C, turn on the cooling water, and quickly inject the perovskite quantum dot precursor solution; S203. After reacting for 0.5 - 2 minutes, quickly cool with an ice - water bath to terminate the reaction and obtain 6OBA - doped perovskite quantum dots; S3. Wash and purify the 6OBA - doped perovskite quantum dots, and disperse them in an organic solvent to obtain a quantum dot dispersion; S4. Spin - coat the quantum dot dispersion obtained in step S3 to prepare a 6OBA - doped perovskite quantum dot film.

[0007] Preferably, the perovskite quantum dots are CsPbBr3 perovskite quantum dots.

[0008] Preferably, in step S201, the molar ratio of 4-(6-(acryloyloxy)hexyloxy)benzoic acid to lead bromide is 0.06 - 0.13:1, heat to 120 °C and continue for 1 hour; in step S202, the volume ratio of oleic acid to oleylamine is 1:3, heat to 180 °C; the reaction time in step S203 is 1 minute.

[0009] Preferably, step S1 specifically includes: Mix a cesium source, OA, and ODE, stir under an argon atmosphere, heat to 115 - 125 °C and continue for 1 hour to obtain a mixture; heat the mixture to 145 - 155 °C under an argon atmosphere, turn on the cooling water, and prepare a Cs - OA precursor solution after the mixture is completely dissolved.

[0010] Preferably, the cesium source in step S1 is cesium carbonate; heat to 120 °C and continue for 1 hour to obtain a mixture; heat the mixture to 150 °C under an argon atmosphere.

[0011] Preferably, step S3 includes: Mix the 6OBA - doped perovskite quantum dots obtained in step S2 with ethyl acetate, centrifuge at a speed of 7000 - 10000 revolutions per minute for 5 - 15 minutes; pour off the supernatant, after the remaining liquid evaporates, disperse the quantum dots at the bottom of the centrifuge tube in n - hexane to obtain a quantum dot dispersion.

[0012] Preferably, the centrifugation speed in step S2 is 8000 revolutions per minute, and the centrifugation time is 10 minutes.

[0013] Preferably, step S4 specifically includes: spin-coating the quantum dot dispersion liquid in step S3 at a rotation speed of 2500-3500 revolutions per minute for 1-3 minutes; after spin-coating, annealing at 90-100 °C for 20-40 min, and after annealing, a 6OBA-doped perovskite quantum dot film is obtained.

[0014] Preferably, the rotation speed of spin-coating is 3000 revolutions per minute, and the spin-coating time is 1 minute; the annealing temperature is 92 °C and the time is 30 minutes.

[0015] The second object of the present invention is to provide a 6OBA-doped perovskite quantum dot film, which is prepared by a preparation method of a 6OBA-doped perovskite quantum dot film.

[0016] Compared with the prior art, the present invention can achieve the following beneficial effects: The present invention uses a new dopant 4-(6-(acryloyloxy)hexyloxy)benzoic acid (6OBA), designs a new synthesis route, and prepares 6OBA liquid crystal-doped CsPbBr3 perovskite quantum dots by a thermal injection method. Through the carboxyl group of 6OBA liquid crystal and Pb 2+ in the perovskite quantum dots are combined to form a stable ligand, successfully passivating the defects of the perovskite quantum dots, improving the photoluminescence quantum efficiency (PLQY) of the perovskite quantum dots, and as the amount of 6OBA increases, the PLQY gradually increases; a 6OBA liquid crystal-doped CsPbBr3 perovskite quantum dot film is prepared by a one-step spin-coating method. Utilize the phase transition characteristics and high stability of liquid crystal materials to spontaneously heal the perovskite structure and surface defects. After annealing at its phase transition temperature, a more uniform perovskite quantum dot film is obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a physical diagram of a 6OBA-doped perovskite quantum dot film provided in Embodiments 1-4 of the present invention.

[0018] Figure 2 is a photoluminescence diagram of a 6OBA-doped perovskite quantum dot film provided in Embodiments 1-4 of the present invention.

[0019] Figure 3 is an ultraviolet-visible absorption spectrum diagram of a 6OBA-doped perovskite quantum dot film provided in Embodiments 1-4 of the present invention.

[0020] Figure 4 is a photoluminescence quantum yield diagram of a 6OBA-doped perovskite quantum dot film provided in Embodiments 1-4 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0021] In the following, embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, the same modules are denoted by the same reference numerals. In the case of the same reference numerals, their names and functions are also the same. Therefore, their detailed descriptions will not be repeated.

[0022] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation to the present invention.

[0023] The present invention provides a method for preparing a 6OBA-doped perovskite quantum dot film, which specifically includes the following steps: S1. Prepare a perovskite quantum dot precursor solution; Specifically, the perovskite quantum dots are CsPbBr3 perovskite quantum dots; Specifically, step S1 includes: mixing a cesium source, OA and ODE, stirring in an argon atmosphere, heating to 115-125 °C and maintaining for 1 hour to obtain a mixture; heating the mixture to 145-155 °C in an argon atmosphere, turning on the cooling water, and preparing a Cs-OA precursor solution after the mixture is completely dissolved. In a specific embodiment, the cesium source is cesium carbonate (Cs2CO3); step S1 specifically includes: adding the cesium source, OA, and ODE into a 50 mL three-necked flask, stirring in an argon atmosphere, heating to 120 °C and maintaining for 1 hour to obtain a mixture; heating the mixture to 150 °C in an argon atmosphere, turning on the cooling water, and preparing a Cs-OA precursor solution after the mixture is completely dissolved.

[0024] S2. Prepare 4-(6-(acryloyloxy)hexyloxy)benzoic acid (6OBA)-doped perovskite quantum dots; specifically including the following sub-steps: S201. Add 6OBA, lead bromide (PbBr2), and octadecene (ODE) into a 50 mL three-necked flask, stir in an argon atmosphere, and heat to 115-125 °C and maintain for 0.5-1.5 hours; S202. Mix oleic acid (OA) and oleylamine (OAm), quickly inject them into the reaction flask with a syringe, and continue stirring until completely dissolved; after the solution becomes clear, heat to 175-185 °C, turn on the cooling water, and quickly inject the perovskite quantum dot precursor solution; S203. After reacting for 0.5-2 minutes, quickly cool with an ice-water bath to terminate the reaction and obtain 6OBA-doped perovskite quantum dots; Specifically, in step S201, the molar ratio of 4-(6-(acryloyloxy)hexyloxy)benzoic acid (6OBA) to lead bromide (PbBr2) is 0.06 to 0.13:1, and the temperature is raised to 120 °C and maintained for 1 hour; in step S202, the volume ratio of oleic acid (OA) to oleylamine (OAm) is 1:3, and the temperature is raised to 180 °C; the reaction time in step S203 is 1 minute. In a specific embodiment, step S2 specifically includes the following sub-steps: S201. Add 0.012 mmol of 6OBA, 0.2 mmol PbBr2 (0.0734 g), and ODE (12 mL) to a 50 mL three-necked flask, stir under an argon atmosphere, raise the temperature to 120 °C and maintain for 1 hour. S202. Mix OA (0.5 ml) and OAm (1.5 ml), quickly inject them into the reaction flask with a syringe, and continue stirring until completely dissolved; after the solution becomes clear, raise the temperature to 180 °C, turn on the cooling water, and quickly inject 1 ml of Cs-OA precursor solution. S203. After reacting for 1 minute, cool with an ice-water bath to terminate the reaction and obtain 6OBA-doped perovskite quantum dots.

[0025] S3. Wash, purify the 6OBA-doped perovskite quantum dots, and disperse them in an organic solvent to obtain a quantum dot dispersion. Specifically, ethyl acetate is used as the purification agent, and the organic solvent is n-hexane. Specifically, step S3 includes: mixing the 6OBA-doped perovskite quantum dots obtained in step S2 with ethyl acetate, centrifuging at a speed of 7000 to 10000 revolutions per minute for 5 to 15 minutes; pour off the supernatant, after evaporating the remaining liquid, disperse the quantum dots at the bottom of the centrifuge tube in n-hexane to obtain a quantum dot dispersion. In a specific embodiment, the centrifugation speed is 8000 revolutions per minute and the centrifugation time is 10 minutes.

[0026] S4. Spin-coat the quantum dot dispersion in step S3 to prepare a 6OBA-doped perovskite quantum dot film. Specifically, step S4 specifically includes: spin-coating the quantum dot dispersion in step S3 at a speed of 2500 to 3500 revolutions per minute for 1 to 3 minutes; after spin-coating, anneal at 90 to 100 °C for 20 to 40 min, and obtain a In a specific embodiment, take 200 μL of the quantum dot dispersion for spin-coating, the spin-coating speed is 3000 revolutions per minute, and the spin-coating time is 1 minute; the annealing temperature is 92 °C and the annealing time is 30 minutes.

[0027] Example 1 This embodiment provides a method for preparing a 6OBA-doped perovskite quantum dot film, which specifically includes the following steps: S1. Add Cs2CO3 (0.386 g, 1.18 mmol), OA (1.27 mL), and ODE (18.73 mL) into a 50 mL three-necked flask, stir under an argon atmosphere, heat up to 120 °C and keep for 1 hour. Then, heat the mixture to 150 °C under an argon atmosphere, turn on the cooling water. After the mixture is completely dissolved, a Cs-OA precursor is prepared. S2. Prepare 4-(6-(acryloyloxy)hexyloxy)benzoic acid-doped perovskite quantum dots; specifically including the following sub-steps: S201. Add 0.012 mmol of 6OBA, PbBr2 (0.0734 g, 0.2 mmol), and ODE (12 mL) into a 50 mL three-necked flask, stir under an argon atmosphere, heat up to 120 °C and keep for 1 hour. S202. Mix OA (0.5 ml) and OAm (1.5 ml), quickly inject them into the reaction flask with a syringe, and continue stirring until completely dissolved. After the solution becomes clear, heat it up to 180 °C, turn on the cooling water, and quickly inject 1 ml of the Cs-OA precursor solution. S203. After reacting for 1 minute, cool it with an ice-water bath to terminate the reaction, and obtain 6OBA-doped perovskite quantum dots. S3. Mix the 6OBA-doped CsPbBr3 perovskite quantum dots obtained in step 2) with about 15 mL of ethyl acetate, centrifuge at a speed of 8000 revolutions per minute for 10 minutes; pour off the supernatant. After the remaining liquid evaporates, disperse the quantum dots at the bottom of the centrifuge tube into n-hexane to obtain a quantum dot dispersion. S4. Take 200 μL of the obtained quantum dot dispersion, set the rotation speed at 3000 revolutions per minute, spin-coat for 1 minute, and then set the annealing temperature at 92 °C according to the liquid crystal phase temperature range. After annealing for 30 minutes, a 6OBA liquid crystal-doped CsPbBr3 perovskite quantum dot film is obtained (for the physical picture, see Figure 1 ).

[0028] Example 2 This embodiment provides a method for preparing a 6OBA-doped perovskite quantum dot film, which specifically includes the following steps: S1. Add Cs2CO3 (0.386 g, 1.18 mmol), OA (1.27 mL), and ODE (18.73 mL) into a 50 mL three-necked flask, stir under an argon atmosphere, heat up to 120 °C and keep for 1 hour. Then, heat the mixture to 150 °C under an argon atmosphere, turn on the cooling water. After the mixture is completely dissolved, a Cs-OA precursor is prepared. S2. Prepare 4-(6-(acryloyloxy)hexyloxy)benzoic acid-doped perovskite quantum dots; specifically including the following sub-steps: S201. Add 0.014 mmol of 6OBA, PbBr2 (0.0734 g, 0.2 mmol), and ODE (12 mL) into a 50 mL three-necked flask, stir under an argon atmosphere, heat up to 120 °C and continue for 1 hour; S202. Mix OA (0.5 ml) and OAm (1.5 ml), quickly inject them into the reaction flask with a syringe, and continue stirring until completely dissolved. After the solution becomes clear, heat up to 180 °C, turn on the condenser water, and quickly inject 1 ml of Cs-OA precursor solution; S203. After reacting for 1 minute, cool with an ice-water bath to terminate the reaction and obtain 6OBA-doped perovskite quantum dots; S3. Mix the 6OBA-doped CsPbBr3 perovskite quantum dots obtained in step 2) with about 15 mL of ethyl acetate, centrifuge at a speed of 8000 revolutions per minute for 10 minutes; pour off the supernatant. After the remaining liquid evaporates, disperse the quantum dots at the bottom of the centrifuge tube in n-hexane to obtain a quantum dot dispersion; S4. Take 200 μL of the obtained quantum dot dispersion, set the rotation speed at 3000 revolutions per minute, spin-coat for 1 minute, and then set the annealing temperature at 92 °C according to the liquid crystal phase temperature range. After annealing for 30 minutes, obtain a 6OBA liquid crystal-doped CsPbBr3 perovskite quantum dot film (for the physical picture, see Figure 1 )

[0029] Example 3 This example provides a method for preparing a 6OBA-doped perovskite quantum dot film, specifically including the following steps: S1. Add Cs2CO3 (0.386 g, 1.18 mmol), OA (1.27 mL), and ODE (18.73 mL) into a 50 mL three-necked flask, stir under an argon atmosphere, heat up to 120 °C and continue for 1 hour. Then, heat the mixture to 150 °C under an argon atmosphere, turn on the condenser water, and prepare a Cs-OA precursor after the mixture is completely dissolved; S2. Prepare 4-(6-(acryloyloxy)hexyloxy)benzoic acid-doped perovskite quantum dots; specifically including the following sub-steps: S201. Add 0.018 mmol of 6OBA, PbBr2 (0.0734 g, 0.2 mmol), and ODE (12 mL) into a 50 mL three-necked flask, stir under an argon atmosphere, heat up to 120 °C and continue for 1 hour; S202. Mix OA (0.5 ml) and OAm (1.5 ml), and quickly inject the mixture into the reaction flask using a syringe. Continue stirring until completely dissolved. After the solution becomes clear, heat it to 180 °C, turn on the cooling water, and quickly inject 1 ml of the Cs-OA precursor solution; S203. After reacting for 1 minute, cool it with an ice-water bath to terminate the reaction, and obtain 6OBA-doped perovskite quantum dots; S3. Mix the 6OBA-doped CsPbBr3 perovskite quantum dots obtained in step 2) with about 15 mL of ethyl acetate, and centrifuge at a speed of 8000 revolutions per minute for 10 minutes; Pour off the supernatant. After the remaining liquid evaporates, disperse the quantum dots at the bottom of the centrifuge tube in n-hexane to obtain a quantum dot dispersion; S4. Take 200 μL of the obtained quantum dot dispersion, set the rotation speed to 3000 revolutions per minute, spin-coat for 1 minute, and then set the annealing temperature to 92 °C according to the liquid crystal phase temperature range. After annealing for 30 minutes, obtain a 6OBA liquid crystal-doped CsPbBr3 perovskite quantum dot film (for the physical picture, see Figure 1 )

[0030] Example 4 This example provides a method for preparing a 6OBA-doped perovskite quantum dot film, which specifically includes the following steps: S1. Add Cs2CO3 (0.386 g, 1.18 mmol), OA (1.27 mL), and ODE (18.73 mL) to a 50 mL three-necked flask, stir under an argon atmosphere, heat to 120 °C and maintain for 1 hour. Then, heat the mixture to 150 °C under an argon atmosphere, turn on the cooling water, and prepare a Cs-OA precursor after the mixture is completely dissolved; S2. Prepare 4-(6-(acryloyloxy)hexyloxy)benzoic acid-doped perovskite quantum dots; specifically, it includes the following sub-steps: S201. Add 0.026 mmol of 6OBA, PbBr2 (0.0734 g, 0.2 mmol), and ODE (12 mL) to a 50 mL three-necked flask, stir under an argon atmosphere, and heat to 120 °C and maintain for 1 hour; S202. Mix OA (0.5 ml) and OAm (1.5 ml), and quickly inject the mixture into the reaction flask using a syringe. Continue stirring until completely dissolved. After the solution becomes clear, heat it to 180 °C, turn on the cooling water, and quickly inject 1 ml of the Cs-OA precursor solution; S203. After reacting for 1 minute, cool it with an ice-water bath to terminate the reaction, and obtain 6OBA-doped perovskite quantum dots; S3. Mix the 6OBA-doped CsPbBr3 perovskite quantum dots obtained in step 2) with about 15 mL of ethyl acetate, and centrifuge at a speed of 8000 revolutions per minute for 10 minutes; pour off the supernatant. After the remaining liquid evaporates, disperse the quantum dots at the bottom of the centrifuge tube into n-hexane to obtain a quantum dot dispersion; S4. Take 200 μL of the obtained quantum dot dispersion, set the rotation speed at 3000 revolutions per minute, spin-coat for 1 minute, and then set the annealing temperature at 92 °C according to the liquid crystal phase temperature range. After annealing for 30 minutes, a 6OBA liquid crystal-doped CsPbBr3 perovskite quantum dot film is obtained (for the physical picture, see Figure 1 ).

[0031] Comparative Example 1 This comparative example provides a method for preparing a CsPbBr3 perovskite quantum dot film without 6OBA liquid crystal doping, including the following steps: S1. Add Cs2CO3 (0.386 g, 1.18 mmol), OA (1.27 mL), and ODE (18.73 mL) to a 50 mL three-necked flask, stir under an argon atmosphere, heat up to 120 °C and maintain for 1 hour. Then, heat the mixture to 150 °C under an argon atmosphere, turn on the condensing water, and prepare a Cs-OA precursor after the mixture is completely dissolved; S2. Add PbBr2 (0.0734 g, 0.2 mmol) and ODE (12 mL) to a 50 mL three-necked flask, stir under an argon atmosphere, and heat up to 120 °C and maintain for 1 hour; mix OA (0.5 ml) and OAm (1.5 ml), quickly inject them into the reaction flask with a syringe, and continue stirring until completely dissolved; after the solution becomes clear, heat it up to 180 °C, turn on the condensing water, quickly inject 1 ml of the Cs-OA precursor solution, react for 1 minute, and then cool it with an ice-water bath to terminate the reaction; S3. Mix the CsPbBr3 perovskite quantum dots obtained in step S2 with about 15 mL of ethyl acetate, and centrifuge at a speed of 8000 revolutions per minute for 10 minutes. Pour off the supernatant. After the remaining liquid evaporates, disperse the quantum dots at the bottom of the centrifuge tube into n-hexane; S4. Take 200 μL of the obtained quantum dot dispersion, set the rotation speed at 3000 revolutions per minute, spin-coat for 1 minute, and then set the annealing temperature at 92 °C according to the liquid crystal phase temperature range. After annealing for 30 minutes, a CsPbBr3 perovskite quantum dot film is obtained.

[0032] The emission peak position information and fluorescence quantum efficiency of the 6OBA-doped perovskite quantum dot films prepared in Examples 1 to 4 are given in Table 1.

[0033] Table 1 Optical parameters of 6OBA-doped perovskite quantum dot films

[0034] Figure 2 The photoluminescence spectra of 6OBA-doped perovskite quantum dot films prepared in Examples 1 to 4 are shown. It can be seen from the figure that the photoluminescence peak positions of the examples all exhibit green light emission, which is consistent with Figure 1 correspond.

[0035] Figure 3 The ultraviolet-visible absorption spectra of 6OBA-doped perovskite quantum dot films prepared in Examples 1 to 4 are shown. It can be seen from the figure that the absorption peak positions of the examples are all in the ultraviolet region, indicating that they absorb ultraviolet light.

[0036] Figure 4 The photoluminescence quantum yield diagram of 6OBA-doped perovskite quantum dot films prepared in Examples 1 to 4 is shown. It can be seen from the figure that with the increase of the doping amount, the photoluminescence quantum yield has been significantly improved.

[0037] The present invention uses a new dopant 4-(6-(acryloyloxy)hexyloxy)benzoic acid (6OBA), designs a new synthesis route, and prepares 6OBA liquid crystal-doped CsPbBr3 perovskite quantum dots by the thermal injection method. Through the combination of the carboxyl group of 6OBA liquid crystal with Pb in the perovskite quantum dots, a stable ligand is formed, successfully passivating the perovskite quantum dot defects, improving the photoluminescence quantum efficiency (PLQY) of the perovskite quantum dots, and with the increase of the amount of 6OBA, the PLQY gradually increases; then, a 6OBA liquid crystal-doped CsPbBr3 perovskite quantum dot film is prepared by a one-step spin-coating method. Utilizing the phase change characteristics and high stability of the liquid crystal material to spontaneously heal the perovskite structure and surface defects, a more uniform perovskite quantum dot film is obtained after annealing at its phase change temperature. 2+ Combined, a stable ligand is formed, successfully passivating the perovskite quantum dot defects, improving the photoluminescence quantum efficiency (PLQY) of the perovskite quantum dots, and with the increase of the amount of 6OBA, the PLQY gradually increases; then, a 6OBA liquid crystal-doped CsPbBr3 perovskite quantum dot film is prepared by a one-step spin-coating method. Utilizing the phase change characteristics and high stability of the liquid crystal material to spontaneously heal the perovskite structure and surface defects, a more uniform perovskite quantum dot film is obtained after annealing at its phase change temperature.

[0038] In summary, the present invention provides a liquid crystal dopant 4-(6-(acryloyloxy)hexyloxy)benzoic acid (6OBA), whose special functional groups can effectively passivate perovskite quantum dots. At the same time, its strong morphology control and self-assembly ability can regulate the growth of perovskite crystals and their film morphology; it is proposed to prepare 6OBA liquid crystal-doped CsPbBr3 perovskite quantum dots by a stepwise thermal injection method and then spin-coat to achieve quantum dot passivation and film self-repair.

[0039] It should be understood that the various forms of processes shown above can be used, reordering, adding or deleting steps. For example, the steps recorded in the disclosure of the present invention can be executed in parallel, sequentially, or in a different order, as long as the desired results of the technical solution disclosed in the present invention can be achieved, and no limitation is made herein.

[0040] The above specific embodiments do not constitute a limitation on the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of 6OBA-doped perovskite quantum dot film, characterized in that: Specifically, it includes the following steps: S1. Prepare a perovskite quantum dot precursor solution; S2. Prepare 4-(6-(acryloyloxy)hexyloxy)benzoic acid-doped perovskite quantum dots; specifically, it includes the following sub-steps: S201. Mix 4-(6-(acryloyloxy)hexyloxy)benzoic acid, lead bromide, and octadecene, stir under an argon atmosphere, heat to 115 - 125 °C and keep for 0.5 - 1.5 hours; S202. Mix oleic acid and oleylamine, quickly inject them into the reaction flask with a syringe, continue stirring until completely dissolved; after the solution becomes clear, heat to 175 - 185 °C, turn on the condenser water, and quickly inject the perovskite quantum dot precursor solution; S203. After reacting for 0.5 - 2 minutes, quickly cool with an ice-water bath to terminate the reaction and obtain 6OBA-doped perovskite quantum dots; S3. Wash, purify the 6OBA-doped perovskite quantum dots, and disperse them in an organic solvent to obtain a quantum dot dispersion; S4. Spin-coat the quantum dot dispersion in step S3 to prepare a 6OBA-doped perovskite quantum dot film.

2. The preparation method of a 6OBA-doped perovskite quantum dot thin film according to claim 1, wherein: The perovskite quantum dots are CsPbBr3 perovskite quantum dots.

3. The preparation method of a 6OBA-doped perovskite quantum dot thin film according to claim 1, characterized in that: In step S201, the molar ratio of 4-(6-(acryloyloxy)hexyloxy)benzoic acid to lead bromide is 0.06 - 0.13:1, heat to 120 °C and keep for 1 hour; in step S202, the volume ratio of oleic acid to oleylamine is 1:3, heat to 180 °C; the reaction time in step S203 is 1 minute.

4. The preparation method of a 6OBA-doped perovskite quantum dot film according to claim 1, characterized in that: Step S1 specifically includes: Mix a cesium source, OA, and ODE, stir under an argon atmosphere, heat to 115 - 125 °C and keep for 1 hour to obtain a mixture; heat the mixture to 145 - 155 °C under an argon atmosphere, turn on the condenser water, and prepare a Cs-OA precursor solution after the mixture is completely dissolved.

5. The preparation method of a 6OBA-doped perovskite quantum dot thin film according to claim 4, wherein: The cesium source in step S1 is cesium carbonate; heat to 120 °C and keep for 1 hour to obtain a mixture; heat the mixture to 150 °C under an argon atmosphere.

6. The preparation method of a 6OBA-doped perovskite quantum dot thin film according to claim 1, wherein: Step S3 includes: Mix the 6OBA-doped perovskite quantum dots obtained in step S2 with ethyl acetate, centrifuge at a speed of 7000 - 10000 revolutions per minute for 5 - 15 minutes; pour off the supernatant, after the remaining liquid evaporates, disperse the quantum dots at the bottom of the centrifuge tube in n-hexane to obtain a quantum dot dispersion.

7. The preparation method of a 6OBA-doped perovskite quantum dot thin film according to claim 6, characterized in that: In step S2, the centrifugation speed is 8000 revolutions per minute and the centrifugation time is 10 minutes.

8. The preparation method of a 6OBA-doped perovskite quantum dot film according to claim 1, characterized in that: Step S4 specifically includes: Spin-coat the quantum dot dispersion in step S3 at a speed of 2500 - 3500 revolutions per minute for 1 - 3 minutes; after spin-coating, anneal at 90 - 100 °C for 20 - 40 min, and obtain a 6OBA-doped perovskite quantum dot film after annealing.

9. The preparation method of a 6OBA-doped perovskite quantum dot thin film according to claim 8, characterized in that: The spin-coating speed is 3000 revolutions per minute and the spin-coating time is 1 minute; the annealing temperature is 92 °C and the time is 30 minutes.

10. A 6OBA-doped perovskite quantum dot thin film, characterized in that: Prepared by using the preparation method of a 6OBA-doped perovskite quantum dot film described in any one of claims 1 - 9.

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