Synthesis method of high-temperature-resistant and anti-agglomeration perovskite quantum dots

Abstract

The invention belongs to the technical field of material chemistry, and relates to a synthesis method of a high-temperature-resistant anti-agglomeration perovskite quantum dot, which comprises the following steps: weighing CsCl, MnCl2, NiCl2, NaCl, InCl3 and CoCl2 as raw materials according to the proportion of a chemical formula Cs (MnNibNacIndCoe) Cl6, carrying out first ball milling, second ball milling and centrifugal separation, then carrying out first drying treatment, grinding into coarse powder particles, carrying out second drying treatment, grinding into powder, and carrying out drying treatment to obtain the high-temperature-resistant anti-agglomeration perovskite quantum dot. A uniform quantum dot solution is formed through dispersion of a cyclohexane solvent, a perovskite quantum dot film is formed on the surface of an inert substrate silicon wafer, deposition circulation operation is carried out in a low-vacuum environment, and a high-temperature-resistant and anti-agglomeration perovskite quantum dot product is obtained. The high temperature resistance of the quantum dots can be improved to 200 DEG C or above, the quantum dots have super-dispersity and are not prone to agglomeration, long-time stable work is achieved, and the bottlenecks of high-temperature phase change and incapability of industrialization are broken through.

Description

Technical Field

[0001] The present invention belongs to the technical field of material chemistry, and in particular relates to a method for synthesizing high-temperature-resistant and anti-agglomeration perovskite quantum dots. Background Art

[0002] Perovskite quantum dots, with their unique optical and electrical properties, have shown great potential for application in optoelectronic devices, bioimaging, and other fields. However, in practical applications, they face many technical bottlenecks that need to be addressed. On the one hand, perovskite quantum dots have inherent performance flaws. Because they contain lead, they pose a toxic risk and a potential threat to the environment and human health. At high temperatures (>100°C), the perovskite lattice tends to expand, inducing phase separation. For example, CsPbI3 can transition from the α phase to the δ phase, severely impacting material performance. Furthermore, the migration of Pb²⁺ and halide ions exacerbates fluorescence quenching, shortening the quantum dot lifetime. Furthermore, due to their high surface energy, they are prone to agglomeration, reducing their stability and uniformity. On the other hand, existing preparation and packaging technologies have shortcomings. Currently used methods to improve the performance of perovskite quantum dots, such as atomic layer deposition (ALD) and laser processing, are costly and difficult to achieve on a large scale. Regarding packaging, inorganic framework packaging requires high-temperature processing (≥400°C), which is not only energy-intensive but can also damage the optical properties of the quantum dots. While simple to operate, polymer packaging is prone to aging and cracking in long-term high-temperature environments and cannot effectively isolate them from environmental corrosion, making the commercial application of perovskite quantum dots in extremely harsh environments difficult. The main reasons for the high-temperature failure of perovskite quantum dots are as follows: ①Crystal structure collapse; ②Surface ligands fall off at high temperature; ③ Non-radiative recombination caused by energy level mismatch.

[0003] Therefore, there is an urgent need to develop a synthesis method for high-temperature resistant and anti-agglomeration perovskite quantum dots that can overcome the above-mentioned defects in order to promote their widespread application in actual production. Summary of the Invention

[0004] The purpose of the present invention is to develop a method for synthesizing high-temperature resistant and anti-agglomeration perovskite quantum dots. The method reduces the surface active energy while preventing the ligands from falling off through the strong coupling effect between multiple strong ligands and the quantum dot surface, and adopts the process technology of organic-inorganic composite process encapsulation to achieve a synergistic effect of high-temperature resistance and anti-agglomeration, effectively improve the high-temperature resistance and anti-agglomeration performance of perovskite quantum dots, and maintain excellent optical properties at the same time, so as to solve the technical problems of low long-term stability of perovskite quantum dots in high-temperature environments and high large-scale process costs.

[0005] To achieve the above object, the present invention is implemented according to the following technical solutions: A method for synthesizing high-temperature resistant and anti-agglomeration perovskite quantum dots comprises the following steps: S1, according to the chemical formula Cs(Mn a Ni b Na c In d Co e )Cl6 ratio, weighing CsCl, MnCl2, NiCl2, NaCl, InCl3 and CoCl2 as raw materials; wherein a+b+c+d+e=1, and a>0, b>0, c>0, d>0, e>0; S2, placing the above raw materials in a ball milling jar in sequence, and performing a first ball milling in a high-energy ball mill; after the first ball milling is completed, adding strong organic ligands 1-hexanethiol, oleylamine, and PMMA, and performing a second ball milling; after the second ball milling is completed, a ball-milled powder is obtained; S3, uniformly dispersing the ball-milled powder in cyclohexane by a first ultrasonic dispersion to obtain a dispersed liquid; S4, transferring the dispersed liquid to a centrifuge tube and centrifuging, discarding the supernatant, adding toluene to the centrifuge tube again, dispersing the precipitate by a second ultrasonic dispersion, and centrifuging again; S5, after repeating step S4 several times, the centrifuge tube is placed in a drying oven for a first drying process to obtain a primary dried product; S6, placing the primary dried product in a crusher, adding polystyrene, grinding into coarse powder particles, and then placing it in a drying oven for a second drying process to obtain a secondary dried product; S7, grinding the secondary dried product into powder in a quartz mortar to obtain perovskite quantum dots; S8, dispersing the perovskite quantum dots in a cyclohexane solvent to form a uniform quantum dot solution, removing impurities by centrifugation or filtration, dropping the quantum dot solution onto the surface of an inert substrate silicon wafer, wrapping it with plastic wrap, and placing it in a cool place at room temperature to form a perovskite quantum dot film; S9, depositing the perovskite quantum dot film in a low vacuum environment and performing a cyclic operation to obtain a high-temperature resistant and anti-agglomeration perovskite quantum dot product.

[0006] Preferably, the chemical formula Cs(Mn a Ni b Na c In d Co e )In Cl6, a:b:c:d:e= 1:1:1:1:1.

[0007] Preferably, in step S2, the volume ratio of the strong organic ligand 1-hexanethiol, oleylamine and PMMA added to the ball mill is 1:1:2.

[0008] More preferably, in step S2, raw materials and zirconia balls (the diameter of the zirconia balls is 12.7 mm) are added to a ball mill with a capacity of 2.5-10 g according to the capacity requirement of the ball mill. After the first ball milling is completed, 20-40 μL of a strong organic ligand 1-hexanethiol, 20-40 μL of oleylamine and 40-80 μL of PMMA are added to the ball mill using a pipette for a second ball milling.

[0009] Preferably, in step S2, the ball-to-material ratio of the first ball milling is (5-8):1, the first ball milling time is 5 min, the rotation speed is 875 rpm; and the second ball milling time is 25 min.

[0010] Preferably, in step S3, the first ultrasonic dispersion time is 10 min.

[0011] Preferably, in step S4, the time of each centrifugation treatment is 10 min, the rotation speed is 10000 rpm, and the time of the second ultrasonic dispersion is 10 min.

[0012] Preferably, in step S5, the temperature of the first drying treatment is 60° C. and the time is 4 h. Preferably, in step S6, the amount of polystyrene added is 1 mL, the temperature of the second drying treatment is 60° C., and the time is 2 h.

[0013] Preferably, in step S9, the deposition cycle operation includes the following steps: S91, perform precursor A pulse: pulse precursor A into the reaction chamber so that it chemically adsorbs with the hydroxyl groups or active sites on the surface of the perovskite quantum dots to form an Al-O intermediate layer; S92, perform precursor B pulse: pulse precursor B into the reaction chamber so that it reacts with Al on the surface of the Al-O intermediate layer to generate Al2O3; S93, blow off the residual reactants and by-products; S94, repeat the above steps S91-S93, depositing a single atomic layer in each cycle until the target wrapping thickness is reached, thus obtaining a high-temperature resistant and anti-agglomeration perovskite quantum dot product.

[0014] Preferably, in step S9, the pressure of the low vacuum environment is 0.1-10 Pa, the temperature is 100° C., the precursor A is trimethylaluminum, and the precursor B is water vapor or oxygen.

[0015] The working principle of the present invention: The present invention synthesizes a high-entropy two-dimensional double perovskite material with high temperature resistance and anti-agglomeration through a two-step solid-phase high-energy ball milling method. The present invention introduces a double strong ligand to tightly anchor the quantum dots to modify the surface, which will reduce ligand shedding and ion migration at high temperatures, achieve efficient light emission at room temperature, and improve thermal stability. Secondly, the introduction of Mn 2+ 、In 3+ Plasma doping stabilizes the crystal lattice and reduces surface reactivity, thereby achieving long-term stability and reducing agglomeration of quantum dots. In terms of process technology, the use of inorganic-organic composite encapsulation technology, combining atomic layer deposition technology with polymer composites to achieve double encapsulation, significantly improves high-temperature resistance.

[0016] At the same time, the synthesis conditions were optimized. By precisely controlling the milling time and rotation speed during the two high-energy ball milling stages, the quantum dots were grown in a suitable environment, forming uniform, size-controlled quantum dots. Furthermore, multiple experimental tests of the introduced amounts of multiple ligands confirmed that a 1:1:2 ratio was ultimately used to achieve the best high-temperature resistance of the high-entropy quantum dots.

[0017] Compared with the prior art, the present invention has the following beneficial effects: The high-entropy perovskite multiphase solid solution technology used in the present invention assists in multi-ligand atomic-level modification and encapsulation technology through an inorganic-organic composite process, while solving the problems of perovskite quantum dots' inability to withstand high temperatures and agglomeration. It can improve the high-temperature resistance of quantum dots to above 200°C and have super-dispersion and are not easy to agglomerate, achieving long-term stable operation. This technology breaks through the bottlenecks of high-temperature phase change and inability to industrialize, and has broad application prospects in the fields of light-emitting devices, solar cells, etc., providing strong technical support for the practical application of perovskite quantum dots. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 1 is a process flow chart of the present invention in the embodiments.

[0019] Figure 2 This is a stability test chart of the perovskite quantum dot product prepared by the present invention at high temperature in the example. DETAILED DESCRIPTION

[0020] The present invention will be further described below with reference to specific embodiments. The illustrative embodiments and descriptions of the present invention are intended to explain the present invention but are not intended to limit the present invention.

[0021] All raw materials of the present invention are not particularly limited in their sources and can be purchased from the market or prepared according to conventional methods well known to those skilled in the art.

[0022] There is no particular limitation on the purity of all raw materials in the present invention, and the present invention preferably adopts conventional purity used in the art.

[0023] The devices used in the present invention are not particularly limited and can be devices commonly used in the art.

[0024] Example: like Figure 1 As shown, this embodiment provides a method for synthesizing high-temperature resistant and anti-agglomeration perovskite quantum dots, comprising the following steps: S1, to prepare 1mmol of Cs(Mn 0.2 Ni 0.2 Na 0.2 In 0.2 Co 0.2 )Cl6 perovskite quantum dots as an example, according to the chemical formula Cs(Mn 0.2 Ni 0.2 Na 0.2 In 0.2 Co 0.2 )Cl6 ratio, weigh CsCl, MnCl2, NiCl2, NaCl, InCl3 and CoCl2 as raw materials; S2, the above raw materials are placed in a ball mill with a capacity of 2.5 g in sequence, and zirconia balls (diameter 12.7 mm) with a ball-to-material ratio of 5-8 are added. A rubber ring is placed on the sealing of the ball mill, the ball mill cover is covered and sealed, and the ball mill is placed in a high-energy ball mill for the first ball milling. Through the combined action of mechanochemistry and the high-speed rotation and vibration of the ball mill, the grinding jar is driven to perform periodic motion. The first ball milling time is 5 min and the rotation speed is 875 rpm. After the first ball milling is completed, the ball mill is transferred to a glove box, the ball mill is opened, and 20 μL of a strong organic ligand 1-hexanethiol, 20 μL of oleylamine (OAm) and 40 μL of PMMA are added to the ball mill using a pipette. The ball mill is resealed and the high-energy ball mill is continued to be used for the second ball milling for 25 min. After the second ball milling, the ball milled powder is obtained. S3, after the second ball milling is completed, take out the ball mill jar and transfer it to a fume hood, open the ball mill jar, and evenly disperse the prepared ball milled powder in cyclohexane, and sonicate for 10 minutes to obtain a dispersed liquid; S4, after the dispersed liquid is transferred to a centrifuge tube and centrifuged, the supernatant is discarded, and a certain amount of toluene is added to the centrifuge tube again. After the precipitate is dispersed by a second ultrasonic dispersion for 10 minutes, the centrifugation is performed again; each centrifugation time is 10 minutes, and the speed is 10000 rpm; S5, after repeating step S4 three times, the centrifuge tube is placed in a drying oven for a first drying process to obtain a primary dried product; the first drying process temperature is 60° C. and the time is 4 h; S6, the primary dried product is placed in a crusher, and 1 mL of polystyrene is added, and the product is ground into coarse powder particles, which is then placed in a drying oven for a second drying process to obtain a secondary dried product; the second drying process is performed at 60°C for 2 h; S7, grinding the secondary dried product in a quartz mortar for 40 min, and further finely grinding it into powder to obtain perovskite quantum dots; S8, dispersing the perovskite quantum dots in a cyclohexane solvent to form a uniform quantum dot solution, removing impurities by centrifugation or filtration, dropping the quantum dot solution onto the surface of an inert substrate silicon wafer, wrapping it with plastic wrap, and placing it in a cool place at room temperature for 24 hours to form a perovskite quantum dot film; S9, depositing the perovskite quantum dot film in a low vacuum environment at a temperature of 100°C and a pressure of 0.1–10 Pa to obtain a high-temperature resistant and anti-agglomeration perovskite quantum dot product.

[0025] Specifically, in step S9, the deposition cycle operation includes the following steps: S91, performing a precursor A pulse: pulsing the precursor A into the reaction chamber so that the precursor A undergoes chemical adsorption with the hydroxyl groups or active sites on the surface of the perovskite quantum dots to form an Al-O intermediate layer; S92, performing a precursor B pulse: pulsing the precursor B into the reaction chamber to react with Al on the surface of the Al-O intermediate layer to generate Al2O3; S93, purging to remove residual reactants and by-products; S94, repeat the above steps, depositing a single atomic layer in each cycle (the thickness of a single cycle is about 0.1~1.1 Å) until the target wrapping thickness of 1~5nm is reached, thus obtaining a high-temperature resistant and anti-agglomeration perovskite quantum dot product.

[0026] Wherein, the precursor A is trimethylaluminum, and the precursor B is water vapor or oxygen.

[0027] The deposited samples were analyzed and characterized to determine their phase composition, high temperature resistance, and anti-agglomeration properties. The experimental data and performance are as follows: (1) Optical performance test The fluorescence performance of the prepared quantum dot solution was tested using a fluorescence spectrometer. The results showed that the quantum dots had a high fluorescence quantum yield, and the emission wavelength could be precisely controlled within the range of 480-700 nm by adjusting the composition of the metal halide. Compared with quantum dots prepared by traditional synthesis methods, the quantum dots prepared by the present invention have significant advantages in optical performance, can be prepared on a larger scale, and have certain performance improvements. The fluorescence quantum yield of quantum dots prepared by traditional methods is generally 70-80%, and the half-peak width of the emission spectrum is wide, about 40-50 nm, while the fluorescence quantum yield of the quantum dots of the present invention can exceed 80%.

[0028] (2) High temperature resistance test The prepared perovskite quantum dots were coated onto an inert silicon wafer substrate and heated at 150°C, 180°C, and 210°C for one hour. Their structure and morphology were then characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that after heating at 150°C and 180°C, the quantum dots' lattice structure remained largely intact, with no significant decomposition or agglomeration. After heating at 210°C, although some quantum dots exhibited slight lattice distortion, they maintained good dispersion and showed no significant agglomeration. In contrast, quantum dots prepared using conventional methods exhibited significant lattice distortion and agglomeration after heating at 80°C for one hour, and almost completely decomposed after heating at 150°C.

[0029] (3) Anti-agglomeration performance test The prepared quantum dot solution was stored at room temperature for 60 days, and the dispersion of the quantum dots was regularly observed. Dynamic light scattering (DLS) was used to measure the particle size distribution of the quantum dots. The results showed that after 60 days of storage, the average particle size of the quantum dots changed little, and the particle size distribution remained relatively uniform, indicating that the quantum dots had not undergone significant aggregation. In contrast, the control quantum dot solution, which did not contain multiple ligands, showed significant aggregation after 10 days of storage, with a significant increase in particle size and a broadening of the particle size distribution.

[0030] Figure 2 The stability test results of the high entropy perovskite quantum dot product at high temperature in this embodiment are shown in FIG. Figure 2 (a) PL spectrum at 150 °C for 8 h; Figure 2 (b) PL spectrum at 180 °C for 8 h; Figure 2 (c) is the PL spectrum after being kept at 210°C for 8 hours. As can be seen from the figure, after 8 hours, the PL of the perovskite quantum dot product in this embodiment can still be maintained above 70%, showing super high temperature resistance.

[0031] From the above experiments, it can be seen that the high-entropy perovskite multiphase solid solution technology adopted in the present invention assists multi-ligand atomic-level modification and the encapsulation technology through an inorganic-organic composite process, while solving the problems of perovskite quantum dots' inability to withstand high temperatures and agglomeration. It can improve the high-temperature resistance of quantum dots to above 200°C and have super dispersion and are not easy to agglomerate, thereby achieving long-term stable operation. This technology breaks through the bottleneck of high-temperature phase change and inability to industrialize, and has broad application prospects in the fields of light-emitting devices, solar cells, etc., providing strong technical support for the practical application of perovskite quantum dots.

[0032] The technical solution of the present invention is not limited to the above-mentioned specific embodiments. Any technical variations made according to the technical solution of the present invention fall within the protection scope of the present invention.

Claims

1. A method for synthesizing high-temperature resistant and anti-agglomeration perovskite quantum dots, characterized in that: The following steps are involved: S1, according to the chemical formula Cs(Mn a Ni b Na c In d Co e )Cl6 ratio, weighing CsCl, MnCl2, NiCl2, NaCl, InCl3 and CoCl2 as raw materials; wherein a+b+c+d+e=1, and a>0, b>0, c>0, d>0, e>0; S2, placing the above raw materials in a ball milling jar in sequence, and performing a first ball milling in a high-energy ball mill; after the first ball milling is completed, adding strong organic ligands 1-hexanethiol, oleylamine, and PMMA, and performing a second ball milling; after the second ball milling is completed, a ball-milled powder is obtained; S3, uniformly dispersing the ball-milled powder in cyclohexane by a first ultrasonic dispersion to obtain a dispersed liquid; S4, transferring the dispersed liquid to a centrifuge tube and centrifuging, discarding the supernatant, adding toluene to the centrifuge tube again, dispersing the precipitate by a second ultrasonic dispersion, and centrifuging again; S5, after repeating step S4 several times, the centrifuge tube is placed in a drying oven for a first drying process to obtain a primary dried product; S6, placing the primary dried product in a crusher, adding polystyrene, grinding into coarse powder particles, and then placing it in a drying oven for a second drying process to obtain a secondary dried product; S7, grinding the secondary dried product into powder in a quartz mortar to obtain perovskite quantum dots; S8, dispersing the perovskite quantum dots in a cyclohexane solvent to form a uniform quantum dot solution, removing impurities by centrifugation or filtration, dropping the quantum dot solution onto the surface of an inert substrate silicon wafer, wrapping it with plastic wrap, and placing it in a cool place at room temperature to form a perovskite quantum dot film; S9, depositing the perovskite quantum dot film in a low vacuum environment and performing a cyclic operation to obtain a high-temperature resistant and anti-agglomeration perovskite quantum dot product.

2. The method for synthesizing high-temperature resistant and anti-agglomeration perovskite quantum dots according to claim 1, characterized in that: The chemical formula Cs(Mn a Ni b Na c In d Co e )In Cl6, a:b:c:d:e= 1:1:1:1:

1.

3. The method for synthesizing high-temperature resistant and anti-agglomeration perovskite quantum dots according to claim 1, characterized in that: In step S2, the volume ratio of the strong organic ligand 1-hexanethiol, oleylamine and PMMA added to the ball mill is 1:1:

2.

4. The method for synthesizing high-temperature resistant and anti-agglomeration perovskite quantum dots according to claim 3, characterized in that: In step S2, raw materials and zirconium oxide balls are added to a ball mill with a capacity of 2.5-10 g according to the capacity requirements of the ball mill. After the first ball milling is completed, 20-40 μL of a strong organic ligand 1-hexanethiol, 20-40 μL of oleylamine, and 40-80 μL of PMMA are added to the ball mill using a pipette for a second ball milling.

5. The method for synthesizing high-temperature resistant and anti-agglomeration perovskite quantum dots according to claim 4, characterized in that: In step S2, the ball-to-material ratio of the first ball milling is (5-8):1, the first ball milling time is 5 minutes, and the rotation speed is 875 rpm; the second ball milling time is 25 minutes.

6. The method for synthesizing high-temperature resistant and anti-agglomeration perovskite quantum dots according to claim 5, characterized in that: In step S3, the first ultrasonic dispersion time is 10 min; in step S4, the time of each centrifugal treatment is 10 min, the rotation speed is 10000 rpm, and the time of the second ultrasonic dispersion is 10 min.

7. The method for synthesizing high-temperature resistant and anti-agglomeration perovskite quantum dots according to claim 6, characterized in that: In step S5, the temperature of the first drying treatment is 60° C. and the time is 4 h.

8. The method for synthesizing high-temperature resistant and anti-agglomeration perovskite quantum dots according to claim 7, characterized in that: In step S6, the amount of polystyrene added is 1 mL, the temperature of the second drying treatment is 60°C, and the time is 2 h.

9. The method for synthesizing high-temperature resistant and anti-agglomeration perovskite quantum dots according to any one of claims 1 to 8, characterized in that: In step S9, the deposition cycle operation includes the following steps: S91, performing a precursor A pulse: pulsing the precursor A into the reaction chamber so that the precursor A undergoes chemical adsorption with the hydroxyl groups or active sites on the surface of the perovskite quantum dots to form an Al-O intermediate layer; S92, pulse precursor B: pulse precursor B into the reaction chamber to react with Al on the surface of the Al-O intermediate layer to generate Al2O3; S93, purge to remove residual reactants and by-products; S94, repeat the above steps S91-S93, depositing a single atomic layer in each cycle until the target wrapping thickness is reached, thus obtaining a high-temperature resistant and anti-agglomeration perovskite quantum dot product.

10. The method for synthesizing high-temperature resistant and anti-agglomeration perovskite quantum dots according to claim 9, characterized in that: In step S9 , the pressure of the low vacuum environment is 0.1-10 Pa, the temperature is 100° C., the precursor A is trimethylaluminum, and the precursor B is water vapor or oxygen.

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