Perovskite nanocrystal with low lead loss and high fluorescence quantum efficiency and preparation method thereof

Abstract

The invention discloses a perovskite nanocrystal with low lead loss and high fluorescence quantum efficiency and a preparation method thereof, which can effectively reduce environmental pollution caused by discharge of lead element, and the preparation method comprises the following steps: placing A2CO3 or A (CH3COOH), lead acetate and metal salt in a container, adding organic acid and a non-coordination solvent to construct a reaction environment, after high temperature dissolution, injecting a halogen reaction source, and after the reaction is completed, adding an organic acid and a non-coordination solvent to prepare a perovskite nanocrystal with low lead loss and high fluorescence quantum efficiency. Performing reaction to synthesize coarse nanocrystals, performing surface reconstruction by using a quaternary ammonium salt solution to promote separation and purification, and cleaning to obtain a clear and transparent quantum dot solution; on the basis of an original ternary synthesis method, nucleation growth of the nanocrystals is achieved by introducing non-toxic metal elements, efficient conversion from lead element feeding to a product is promoted, and therefore the strong emission characteristic and stability of the nanocrystals are guaranteed while lead source emission and environmental pollution in the synthesis process are reduced.

Description

Technical Field

[0001] This invention belongs to the fields of nanotechnology and light-emitting display technology, and relates to perovskite nanocrystals and their preparation methods, specifically to a perovskite nanocrystal with low lead loss and high fluorescence quantum efficiency and its preparation method. Background Technology

[0002] Perovskite nanocrystals, especially all-inorganic cesium lead halide (CsPbX3) with an APbX3 structure and organic-inorganic hybrid perovskite materials, have become one of the core candidate materials for next-generation luminescent materials and optoelectronic devices due to their superior optoelectronic properties—such as high fluorescence quantum efficiency (PLQY), narrow emission half-width at half-maximum, precisely tunable emission wavelength (covering the entire visible light region), and excellent carrier mobility. In recent years, significant progress has been made in the application research of these materials in fields such as light-emitting diodes (LEDs), lasers, solar cells, photodetectors, and scintillators, demonstrating enormous industrialization potential.

[0003] However, the large-scale synthesis and practical application of perovskite nanocrystals still face two key bottlenecks: environmental and biocompatibility issues, and the impact of the synthesis process on material properties. Traditional perovskite nanocrystals use lead as the main metal component. Lead's high toxicity not only limits its application in consumer electronics and bio-related fields, but also leads to the generation of large amounts of lead-containing waste during synthesis and post-processing due to the incomplete conversion of lead sources into products, posing a serious environmental pollution risk. Researchers both domestically and internationally have attempted various strategies to reduce lead usage or seek alternatives. For example, some teams have used elements such as tin (Sn), germanium (Ge), and bismuth (Bi) to completely replace lead; however, the resulting materials exhibit poor stability in air and fluorescence efficiency far lower than lead-based perovskites, making it difficult to meet the requirements of practical devices. Another mainstream approach is to employ ion doping or alloying strategies, introducing divalent or monovalent metal ions (such as Mn)... 2+ Zn 2+ 、Sr 2+ Cu + (e.g., constructing composite perovskite structures to regulate luminescence properties and reduce lead content while maintaining lattice stability. For example, a foreign research group reported that Mn-doped CsPbCl3 achieved orange luminescence.)

[0004] In terms of synthesis methods, hot-injection and ligand-assisted reprecipitation methods have been widely adopted, but they are still not ideal in terms of efficient lead source conversion, control of nanocrystal nucleation and growth, and passivation of surface defects. Excessive use of lead precursors during synthesis, instability of reaction intermediates, and loss of lead ions during subsequent purification all lead to low lead utilization efficiency and potential environmental pollution risks. Furthermore, in conventional synthesis, surface ligands on nanocrystals are prone to detachment or desorption, causing fluorescence quenching and decreased stability, limiting the long-term storage of materials and device integration.

[0005] Therefore, how to significantly reduce lead consumption and improve lead conversion rate while ensuring high fluorescence quantum efficiency and excellent stability, and to establish a scalable and environmentally friendly perovskite nanocrystal preparation process, is a core issue of common concern to researchers and industry both domestically and internationally. Developing a new synthesis and post-processing method that can achieve "low lead consumption, high efficiency, strong luminescence, and high stability" is of great significance for promoting the transition of perovskite nanocrystals from the laboratory to practical applications. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a high-fluorescence quantum efficiency perovskite nanocrystal with low lead loss and its preparation method, thereby reducing lead emissions during intermediates and subsequent purification processes, improving the stability of nanocrystal nucleation, and ensuring the efficiency of high-fluorescence quantum dots.

[0007] To achieve the above objectives, the present invention employs the following technical solution: A method for preparing perovskite nanocrystals with low lead loss and high fluorescence quantum efficiency includes the following steps: Step 1: Take A₂CO₃ or A(CH₃COOH), lead acetate, and B(CH₃COOH) according to an A:Pb:B ion molar ratio of 1:1:(1~2). n The mixture is placed in a container, and sufficient alkyl acid and high-boiling-point alkyl hydrocarbon are added. After purging with nitrogen three times, the mixture is heated under vacuum to 180°C and maintained until the reactants dissolve. The molar ratio of lead acetate to alkyl acid and alkyl hydrocarbon is 1:(5~30):(30~50). Step 2: Rapidly inject the halogen precursor solution into the reaction system of Step 1 at a reaction temperature of 50~200℃, react for 10~180 s, and after the reaction is complete, quickly cool it to room temperature in a water bath to obtain a crude quantum dot solution. Step 3: Disperse the quantum dot solution in a quaternary ammonium salt solution with a concentration of 20-50 mg / ml at a volume ratio of (3-5):1, and obtain the quantum dot precipitate after centrifugation; Step 4: Disperse the precipitate in a quaternary ammonium salt solution with a concentration of 1-5 mg / ml using the volume ratio of quantum dot solution to quaternary ammonium salt solution obtained in Step 3 (3-5):2. Add methyl acetate to the dispersion at a volume ratio of 1:(2-3) and wash in a centrifuge. Repeat twice. Disperse the obtained precipitate in an organic solvent for storage.

[0008] The present invention also has the following technical features: Preferably, the A-site cation in A2CO3 or A(CH3COOH) includes Cs. + CH3NH3+ CH4N2 + or GA + Any one or more combinations thereof.

[0009] Preferably, the B(CH3COOH) n Including any one of strontium acetate, zinc acetate, nickel acetate, manganese acetate, calcium acetate, tin acetate, magnesium acetate, and titanium acetate; The alkyl acid includes any one of oleic acid, linoleic acid, linolenic acid, octyl phosphate, and tetradecyl phosphate; the high-boiling-point alkyl hydrocarbon includes any one of 1-octadecene, 1-eicosene, hexadecane, and n-octadecane.

[0010] Preferably, the halogen precursor solution is prepared by mixing a halogen source and a halogen source solvent at a mass ratio of 1:10.

[0011] Furthermore, the halogen source solvent includes any one of degassed n-octane, toluene, 1-octadecene, 1-eicosene, hexadecane, and n-octadecane.

[0012] Furthermore, the halogen source includes any one of benzoyl X, phenylacetyl X, alkylammonium X, or trimethylsilyl X, alkylammonium X, wherein X represents a halogen atom.

[0013] Preferably, the quaternary ammonium salt solution comprises a toluene solution of any one of bis(decyldimethylammonium bromide), hexadecyltrimethylammonium bromide, and bis(dodecyldimethylammonium bromide).

[0014] Preferably, the centrifugation speed in steps three and four is 8000 rpm / min, and the centrifugation time is 4~6 min.

[0015] Preferably, the organic solvent mentioned in step four includes n-octane or n-hexane.

[0016] The present invention also protects a perovskite nanocrystal with low lead loss and high fluorescence quantum efficiency prepared by the method described above, wherein the prepared perovskite nanocrystal has an APbX3 structure.

[0017] Compared with the prior art, the present invention has the following technical effects: This invention is based on and improves upon the ternary synthesis method by introducing a non-toxic metal acetate (B(CH3COOH)). n The reaction is synergistic with lead acetate, and with precise molar ratio control, the side reaction of lead loss during the reaction is reduced, thus reducing lead emissions. The introduction of non-toxic metal ions does not affect the product structure and reduces the risk of lead pollution, which is in line with the trend of green synthesis and has lower subsequent processing costs. This invention utilizes a combination of alkyl acids and high-boiling-point alkyl hydrocarbons as a solvent system to provide a stable dispersion environment for nanocrystal growth, reducing fluorescence quenching caused by agglomeration. Rapid injection of halogen precursors and short-time reaction control of the crystallization rate yield nanocrystals with uniform size and high crystallinity, ensuring fluorescence emission efficiency. A two-step quaternary ammonium salt treatment, leveraging the hydrophobic chain and cationic groups of the quaternary ammonium salt, effectively passivates nanocrystal surface defects, reconstructs the surface, and reduces non-radiative recombination, maintaining the stability of nanocrystal nucleation and ensuring the efficiency of high-fluorescence quantum dots. This novel synthesis and post-processing method for perovskite nanocrystals achieves "low lead consumption, high efficiency, strong luminescence, and high stability," which is of great significance for promoting the transition of perovskite nanocrystals from the laboratory to practical applications. It gives perovskite nanocrystals broad application potential in display devices, fluorescence detection, and bioimaging, while balancing performance and environmental requirements. The present invention offers flexible and safe raw material selection, a mild and highly controllable preparation process, and is easy to scale up for production. Attached Figure Description

[0018] Figure 1 This is the PL spectrum of Embodiment 1 of the present invention; Figure 2 This is a sample image of Embodiment 1 of the present invention; Figure 3 This is the PL spectrum of Embodiment 2 of the present invention; Figure 4 This is a sample image of Embodiment 2 of the present invention; Figure 5 This is the PL spectrum of Embodiment 3 of the present invention; Figure 6 This is a sample image of Embodiment 3 of the present invention. Detailed Implementation

[0019] The following detailed explanation of the specific content of the present invention is provided in conjunction with embodiments. These descriptions are intended to explain the present invention and not to limit it.

[0020] Example 1 This embodiment provides a method for preparing perovskite nanocrystals with low lead loss and high fluorescence quantum efficiency, comprising the following steps: Step 1: Take 97.8 mg, 227.4 mg, and 246.8 mg of cesium carbonate (Cs2CO3), lead acetate (Pb(CH3COOH)2), and strontium acetate (Sr(CH3COOH)2) respectively according to the A:Pb:B ion molar ratio of 1:1:2 and add them to a three-necked flask. Add 18 ml of oleic acid and 27 ml of ODE (1-octadecene) to the flask and connect the heating device. Evacuate the flask and purge with nitrogen. Repeat this process three times. Then, evacuate the flask to a vacuum and turn on the stirrer. Set the temperature to 180℃ and wait for 2 hours. If the reactants have not dissolved, raise the temperature to 220℃ until all the reactants have dissolved. Stop heating and wait for the system temperature to drop to 70℃. Step 2: Add 0.3 ml of benzoyl bromide to 3 ml of degassed ODE, and quickly inject the prepared solution into the reaction system. After waiting for 1 min of reaction, cool the three-necked flask to room temperature in an ice-water bath to obtain a crude quantum dot solution. Step 3: Take 45 ml of crude quantum dot solution, add 9 ml of 20 mg / ml DDAB (bis(dodecyl dimethyl)bromide) solution, centrifuge at 8000 rpm / min for 6 min, separate the supernatant and precipitate, and discard the supernatant to obtain quantum dot precipitate; Step 4: Add 18 ml of 1 mg / ml DDAB solution to the precipitate, disperse the precipitate, and add 54 ml of methyl acetate solution at a ratio of 1:3. Centrifuge at 8000 rpm / min for 6 min, discard the supernatant again, and repeat this step once more. Finally, add 18 ml of n-hexane to the obtained precipitate for storage.

[0021] Example 2 This embodiment provides a method for preparing perovskite nanocrystals with low lead loss and high fluorescence quantum efficiency, comprising the following steps: Step 1: Take 97.8 mg, 227.4 mg, and 212.2 mg of cesium carbonate (Cs2CO3), lead acetate (Pb(CH3COOH)2), and nickel acetate (Ni(CH3COOH)2) respectively according to the A:Pb:B ion molar ratio of 1:1:2, and add them to a three-necked flask. Add 18 ml of oleic acid and 27 ml of ODE (1-octadecene) to the flask and connect the heating device. Evacuate the flask and purge with nitrogen. Repeat this process three times. Then, evacuate the flask to a vacuum and start stirring. Set the temperature to 180℃ and wait for 2 hours. If the reactants have not dissolved, raise the temperature to 220℃ until all the reactants have dissolved. Stop heating and wait for the system temperature to drop to 70℃. Step 2: Add 0.3 ml of benzoyl bromide to 3 ml of degassed toluene, and quickly inject the prepared solution into the reaction system. After waiting for 1 min to react, cool the three-necked flask to room temperature in an ice-water bath to obtain a crude quantum dot solution. Step 3: Take 45 ml of crude quantum dot solution, add 9 ml of 20 mg / ml DDAB (bis(dodecyl dimethyl)bromide) solution, centrifuge at 8000 rpm / min for 6 min, separate the supernatant and precipitate, and discard the supernatant to obtain quantum dot precipitate; Step 4: Add 18 ml of 1 mg / ml DDAB solution to the precipitate, disperse the precipitate, and add 36 ml of methyl acetate solution at a ratio of 1:2. Centrifuge at 8000 rpm / min for 6 min, discard the supernatant again, and repeat this step once more. Finally, add 18 ml of n-hexane to the obtained precipitate for storage.

[0022] Example 3 This embodiment provides a method for preparing perovskite nanocrystals with low lead loss and high fluorescence quantum efficiency, comprising the following steps: Step 1: Take 97.8 mg, 227.4 mg, and 246.8 mg of cesium carbonate (Cs2CO3), lead acetate (Pb(CH3COOH)2), and strontium acetate (Sr(CH3COOH)2) in a molar ratio of 1:1:2 and add them to a three-necked flask. Add 18 ml of oleic acid and 27 ml of ODE (1-octadecene) to the flask and connect the heating device. Evacuate the flask and purge with nitrogen. Repeat this process three times. Then, evacuate the flask to a vacuum and start stirring. Set the temperature to 200℃ and wait for 2 hours. If the reactants have not dissolved, raise the temperature to 220℃ until all the reactants have dissolved. Stop heating and wait for the system temperature to drop to 160℃. Step 2: Add 250 mg of octadeceneamine iodine to 4 ml of degassed toluene, and quickly inject the prepared solution into the reaction system. After waiting for 10 seconds, cool the three-necked flask to room temperature in an ice-water bath to obtain a crude quantum dot solution. Step 3: Take 45 ml of crude quantum dot solution, add 9 ml of 20 mg / ml DDAB (bis(dodecyl dimethyl)bromide) solution, centrifuge at 8000 rpm / min for 6 min, separate the supernatant and precipitate, and discard the supernatant to obtain quantum dot precipitate; Step 4: Add 18 ml of 1 mg / ml DDAB solution to the precipitate, disperse the precipitate, and add 54 ml of methyl acetate solution at a ratio of 1:3. Centrifuge at 8000 rpm / min for 6 min, discard the supernatant again, and repeat this step once more. Finally, add 18 ml of n-hexane to the obtained precipitate for storage.

[0023] The products of Examples 1, 2, and 3 were tested to obtain... Figure 1 —6. Figure 1 ,3 Figures 5 and 6 show the photoluminescence (PL) spectra of Examples 1 (Sr-doped CsPbBr3), 2 (Ni-doped CsPbBr3), and 3 (Sr-doped CsPbI3), respectively. The emission peaks of Examples 1 and 2 are located around 515 nm, corresponding to the green emission of CsPbBr3; the emission peak of Example 3 is located around 680 nm, corresponding to the red emission of CsPbI3. The emission peak curves show sharp peak shapes and narrow half-widths (HWHMs), indicating that the prepared nanocrystals have a uniform size distribution and good crystallinity. The high PL intensity in the figures indicates that the prepared nanocrystals have high fluorescence quantum efficiency (PLQY), especially maintaining strong luminescence characteristics even after Sr or Ni doping. This demonstrates that the present invention effectively suppresses non-radiative recombination and improves luminescence performance by introducing non-toxic metals and surface reconstruction processes.

[0024] Figure 2 , 4 Figures 6 and 7 show the quantum dot solution samples from the corresponding embodiments: Examples 1 and 2 exhibit clear green fluorescence, while Example 3 exhibits red fluorescence; the solutions are uniformly dispersed without obvious turbidity or precipitation, indicating good dispersion of the nanocrystals, no significant aggregation, and effective surface reconstruction and purification processes. The samples show uniform color under natural light, with no obvious discoloration or precipitation, indicating that the prepared nanocrystals possess certain physical and chemical stability in solution, meeting the application requirements of highly stable perovskite materials.

[0025] Example 4 This embodiment provides a method for preparing perovskite nanocrystals with low lead loss and high fluorescence quantum efficiency, comprising the following steps: Step 1: Apply molar ratio A:Pb:B ions 1:1:1, where A ions are produced by Cs... + Hybrid FA + The reaction mixture consisted of cesium carbonate (Cs2CO3), formamidine acetate (CH4N2CH3COOH), lead acetate (Pb(CH3COOH)2), and strontium acetate (Sr(CH2COOH)2), respectively. These were then added to a three-necked flask. 12 ml of linoleic acid and 16 ml of 1-eicosene were added to the flask, and the heating device was connected. The flask was evacuated and nitrogen gas was introduced. After repeating this process three times, the flask was evacuated again and the stirring was started. The temperature was set to 180℃. After heating for 2 hours, if the reactants did not dissolve, the temperature was increased to 220℃ until all the reactants dissolved. Heating was then stopped, and the system temperature was allowed to drop to 50℃. Step 2: Add 0.3 ml of phenylacetyl bromide to 3 ml of degassed hexadecane, and quickly inject the prepared solution into the reaction system. After waiting for 10 seconds, cool the three-necked flask to room temperature in an ice-water bath to obtain a crude quantum dot solution. Step 3: Take 45 ml of crude quantum dot solution, add 15 ml of 50 mg / ml didecyldimethylammonium bromide solution, centrifuge at 8000 rpm / min for 6 min, separate the supernatant and precipitate, and discard the supernatant to obtain quantum dot precipitate; Step 4: Add 30 ml of 3 mg / ml DDAB solution to the precipitate, disperse the precipitate, and add 54 ml of methyl acetate solution at a ratio of 1:3. Centrifuge at 8000 rpm / min for 4 min, discard the supernatant again, and repeat this step once more. Finally, add 18 ml of n-octane to the obtained precipitate for storage.

[0026] Example 5 This embodiment provides a method for preparing perovskite nanocrystals with low lead loss and high fluorescence quantum efficiency, comprising the following steps: Step 1: Take 97.8 mg of cesium carbonate (Cs2CO3), 227.4 mg of lead acetate (Pb(CH2COOH)2), and 73.11 mg of zinc acetate (Zn(CH2COOH)2) according to the A:Pb:B ion molar ratio of 1:1:1.5 and add them to a three-necked flask. Add 15 ml of octyl phosphate and 20 ml of hexadecane to the flask and connect the heating device. Evacuate the flask and purge with nitrogen. Repeat this process three times. Then, evacuate the flask to a vacuum and turn on the stirrer. Set the temperature to 180°C and wait for 2 hours. If the reactants have not dissolved, raise the temperature to 220°C until all the reactants have dissolved. Stop heating and wait for the system temperature to drop to 200°C. Step 2: Add 0.3 ml of trimethylsilyl bromide to 3 ml of degassed n-octane, and quickly inject the prepared solution into the reaction system. After waiting for 180 s to react, cool the three-necked flask to room temperature in an ice-water bath to obtain a crude quantum dot solution. Step 3: Take 40 ml of crude quantum dot solution, add 10 ml of 40 mg / ml hexadecyltrimethylammonium bromide solution, centrifuge at 8000 rpm / min for 5 min, separate the supernatant and precipitate, and discard the supernatant to obtain quantum dot precipitate; Step 4: Add 20 ml of 5 mg / ml DDAB solution to the precipitate, disperse the precipitate, and add 50 ml of methyl acetate solution at a ratio of 1:2.5. Centrifuge at 8000 rpm / min for 5 min, discard the supernatant again, and repeat this step once more. Finally, add 18 ml of n-hexane to the obtained precipitate for storage.

[0027] In the above embodiments, the A-site cation in A2CO3 can be Cs. + CH3NH 3+ CH4N2 + or GA +Any one of the following; non-toxic metal acetates can be any one of strontium acetate, zinc acetate, nickel acetate, manganese acetate, calcium acetate, tin acetate, magnesium acetate, and titanium acetate; alkyl acids can be any one of oleic acid, linoleic acid, linolenic acid, octyl phosphate, and tetradecyl phosphate; high-boiling alkyl hydrocarbons can be any one of 1-octadecene, 1-eicosene, hexadecane, and n-octadecane; halogen source solvents can be any one of degassed n-octane, toluene, 1-octadecene, 1-eicosene, hexadecane, and n-octadecane; halogen source can be any one of benzoyl X, phenylacetyl X, alkylammonium X, or trimethylsilyl X, wherein X represents a halogen atom.

[0028] This invention discloses a method for preparing perovskite nanocrystals with low lead loss and high fluorescence quantum efficiency. By introducing non-toxic metals, the emission of lead is reduced, promoting its efficient conversion into the product. At the same time, the invention utilizes quaternary ammonium salt solution for surface reconstruction in the post-processing, which can effectively maintain the stability of nanocrystal nucleation and ensure the efficiency of high fluorescence quantum dots.

[0029] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit of the invention. The above embodiments are merely exemplary and should not be construed as limiting the scope of the present invention.

Claims

1. A method for preparing perovskite nanocrystals with low lead loss and high fluorescence quantum efficiency, characterized in that, Includes the following steps: Step 1: Take A₂CO₃ or A(CH₃COOH), lead acetate, and B(CH₃COOH) according to an A:Pb:B ion molar ratio of 1:1:(1~2). n The mixture is placed in a container, and sufficient alkyl acid and high-boiling-point alkyl hydrocarbon are added. After purging with nitrogen three times, the mixture is heated under vacuum to 180°C and maintained until the reactants dissolve. The molar ratio of lead acetate to alkyl acid and alkyl hydrocarbon is 1:(5~30):(30~50). Step 2: Rapidly inject the halogen precursor solution into the reaction system of Step 1 at a reaction temperature of 50~200℃, react for 10~180 s, and after the reaction is complete, quickly cool it to room temperature in a water bath to obtain a crude quantum dot solution. Step 3: Disperse the quantum dot solution in a quaternary ammonium salt solution with a concentration of 10-30 mg / ml at a volume ratio of (3~5):1, and obtain the quantum dot precipitate after centrifugation; Step 4: Disperse the precipitate in a quaternary ammonium salt solution with a concentration of 1-5 mg / ml using the volume ratio of quantum dot solution to quaternary ammonium salt solution obtained in Step 3 (3-5):

1. Add methyl acetate to the dispersion at a volume ratio of 1:(1-3) and wash in a centrifuge. Repeat twice. Disperse the resulting precipitate in an organic solvent and store it.

2. The method for preparing low-lead-loss, high-fluorescence quantum-efficiency perovskite nanocrystals as described in claim 1, characterized in that, The A-site cation in A2CO3 or A(CH3COOH) includes Cs. + CH3NH 3+ CH4N 2+ or GA + Any one or more combinations thereof.

3. The method for preparing low-lead-loss, high-fluorescence quantum-efficiency perovskite nanocrystals as described in claim 1, characterized in that, The aforementioned B(CH3COOH) n Including any one of strontium acetate, zinc acetate, nickel acetate, manganese acetate, calcium acetate, tin acetate, magnesium acetate, and titanium acetate; The alkyl acid includes any one of oleic acid, linoleic acid, linolenic acid, octanoic acid, octyl phosphate, and tetradecyl phosphate; the high-boiling-point alkyl hydrocarbon includes any one of 1-octadecene, 1-eicosene, hexadecane, and n-octadecane.

4. The method for preparing low-lead-loss, high-fluorescence quantum-efficiency perovskite nanocrystals as described in claim 1, characterized in that, The halogen precursor solution is prepared by mixing a halogen source and a halogen source solvent at a mass ratio of 1:

10.

5. The method for preparing low-lead-loss, high-fluorescence quantum-efficiency perovskite nanocrystals as described in claim 4, characterized in that, The halogen source solvent includes any one of degassed n-octane, toluene, 1-octadecene, 1-eicosene, hexadecane, and n-octadecane.

6. The method for preparing low-lead-loss, high-fluorescence quantum-efficiency perovskite nanocrystals as described in claim 4, characterized in that, The halogen source includes any one of benzoyl X, phenylacetyl X, alkylammonium X, or trimethylsilyl X, wherein X represents a halogen atom.

7. The method for preparing low-lead-loss, high-fluorescence quantum-efficiency perovskite nanocrystals as described in claim 1, characterized in that, The quaternary ammonium salt solution includes a toluene solution of any one of bis(decyldimethylammonium bromide), hexadecyltrimethylammonium bromide, and bis(dodecyldimethylammonium bromide).

8. The method for preparing low-lead-loss, high-fluorescence quantum-efficiency perovskite nanocrystals as described in claim 1, characterized in that, The centrifugation speed in steps three and four is 8000 rpm / min, and the centrifugation time is 4~6 min.

9. The method for preparing low-lead-loss, high-fluorescence quantum-efficiency perovskite nanocrystals as described in claim 1, characterized in that, The organic solvent mentioned in step four includes n-octane or n-hexane.

10. A perovskite nanocrystal with low lead loss and high fluorescence quantum efficiency prepared by the method according to any one of claims 1 to 9, characterized in that, The prepared perovskite nanocrystals have an APbX3 structure.

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