A method for preparing antimony-doped cesium indium chloride lead-free perovskite nanocrystals by improved hot injection method

Abstract

The application discloses a method for preparing antimony-doped cesium indium chloride lead-free perovskite nanocrystals through an improved hot injection method. First, cesium carbonate is dissolved by oleic acid to obtain a cesium oleate precursor solution. Then, in another three-necked flask, indium acetate and antimony acetate are dissolved by using 1-octadecene, oleic acid, oleylamine and tri-n-octylphosphine, and the prepared cesium oleate precursor solution is added. After vacuumizing and heating to a certain temperature, a clear solution is obtained. Then, ice-bath cooling is performed, nitrogen is introduced after the temperature is lowered to a certain temperature, isopropyl alcohol and deionized water are injected, and the temperature is raised to a specific temperature. Then, phenyl phosphinic dichloride is rapidly injected. After washing and centrifugation, the target product can be obtained. According to the application, high-quantum-yield antimony-doped cesium indium chloride lead-free perovskite nanocrystals can be prepared at a lower injection temperature and in a shorter time.

Description

Technical Field

[0001] This invention relates to a method for preparing lead-free perovskite nanocrystals, specifically a method for preparing antimony-doped cesium indium chloride lead-free perovskite nanocrystals by an improved hot-injection method. Background Technology

[0002] All-inorganic lead halide perovskite nanocrystals (NCs) are ideal semiconductor materials due to their high charge carrier mobility, high photoluminescence quantum efficiency (PLQY), and tunable luminescence across the entire visible light range. These superior properties make them highly promising for applications in optoelectronics, such as solar cells, photodetectors, light-emitting diodes (LEDs), scintillators, and lasers. However, a significant problem with lead-based perovskite nanocrystals is the toxicity of the heavy metal Pb, which poses a threat to the environment and hinders their large-scale application. Therefore, in recent years, researchers have pursued solutions to replace lead with non-toxic or slightly toxic elements to form lead-free halide perovskites or their variants. Due to their similar electronic structures, elements in the same group as lead have become a focus for lead replacement. Currently, there are numerous studies on lead-free halide perovskite nanocrystals CsBX3 (B=Sn). 2+ 、Ge 2+ Work on (X: halide ions) has been reported. Unfortunately, Sn... 2+ and Ge 2+ Extremely unstable, it is easily oxidized to Sn. 4+ and Ge 4+ .

[0003] Recently, indium (In)-based halide perovskite nanocrystals such as Cs₂AgInCl₆, Cs₂NaInCl₆, Cs₂InCl₅-H₂O, and Cs₃InCl₆ have been found to possess good stability and exhibit coordinated emission properties, and are considered potential alternatives to CsPbX₃ (X = Cl, Br, I). However, compared with CsPbX₃, indium-based halide perovskite nanocrystals generally have lower PLQY, mainly due to the fact that these materials have indirect band gaps or direct band gaps with even-odd forbidden transitions. In previous studies, nanocrystals with 5s⁻¹... 2 Sb of electrons 3+ It has been successfully incorporated into indium-based perovskite nanocrystals. Trace amounts of Sb have been incorporated. 3+ Subsequently, indium-based perovskite nanocrystals can typically achieve broadband self-trapped exciton (STE) emission while simultaneously obtaining high PLQY. Researchers discovered that by changing the composition of the matrix material, the emission of Sb... 3+ The luminescence-dependent emission exhibits significant regulatory effects. Exploring novel indium-based perovskite matrix components and optimizing nanocrystal synthesis methods can further enhance the performance of indium-based perovskite nanocrystals (PLQY), thereby increasing their commercial application potential. Summary of the Invention

[0004] This invention addresses the shortcomings of existing technologies by providing an improved hot-injection method for preparing antimony-doped cesium indium chloride lead-free perovskite nanocrystals. This method offers advantages such as low-temperature injection, rapid and simple operation, and high quantum yield of the obtained nanocrystals.

[0005] This invention relates to a method for preparing antimony-doped cesium indium chloride lead-free perovskite nanocrystals via an improved hot-injection method, comprising the following steps:

[0006] Step 1: Weigh cesium carbonate and add it to a three-necked flask, then add oleic acid. While evacuating the vacuum, heat the solution to a certain temperature, then purge with nitrogen for a certain time until all the cesium carbonate and oleic acid have reacted completely to obtain the cesium oleate precursor solution.

[0007] Step 2: Weigh indium acetate and antimony acetate into another three-necked flask, then add cesium oleate precursor solution, 1-octadecene, oleic acid, oleylamine, and tri-n-octylphosphine. While evacuating the vacuum, heat the solution to a certain temperature. After the precursor materials are completely dissolved, place the three-necked flask in ice water to lower the solution temperature to a certain level. Then, purge with nitrogen gas and inject a mixed solution of isopropanol and deionized water. Next, heat the system to a higher temperature and inject phenylphosphonic dichloride into the flask. Immediately cool the flask with an ice-water bath. After the system temperature cools to room temperature, add a certain amount of ethyl acetate to the flask, centrifuge to remove the supernatant, then add n-hexane to disperse the nanocrystals, centrifuge again to remove the precipitate, and obtain antimony-doped cesium indium chloride lead-free perovskite nanocrystals.

[0008] Furthermore, in step 1, the cesium oleate precursor solution is prepared by dissolving 1.63g of cesium carbonate in 20mL of oleic acid.

[0009] Further, in step 2, the amount of indium acetate added is 0.075 g, the amount of antimony acetate added is 0-0.015 g, the amount of cesium oleate precursor solution added is 2 mL, the amount of 1-octadecene added is 20 mL, the amount of oleic acid added is 2 mL, the amount of oleylamine added is 2 mL, and the amount of tri-n-octylphosphine added is 0.3-0.5 mL.

[0010] Specifically, it is prepared through the following steps:

[0011] Step 1: Weigh 1.63g of cesium carbonate and add it to a three-necked flask. Then add 20mL of oleic acid. While evacuating the vacuum, heat the solution to 140℃ and then purge with nitrogen for 5 minutes until all the cesium carbonate and oleic acid have reacted to obtain the cesium oleate precursor solution.

[0012] Step 2: Weigh 0.075g of indium acetate and 0-0.015g of antimony acetate (e.g., 0g, 0.00075g, 0.00375g, 0.006g, 0.0075g, 0.01125g, 0.015g) into another three-necked flask. Then add 2mL of cesium oleate precursor solution, 20mL of 1-octadecene, 2mL of oleic acid, 2mL of oleylamine, and 0.3-0.5mL of tri-n-octylphosphine. While evacuating the vacuum, heat the solution to 140°C and keep it at that temperature for 5 minutes. Then place the three-necked flask in ice water to lower the solution temperature to 70°C. Then purge with nitrogen gas and inject a mixed solution of 0.5mL of isopropanol and 0-2.03mL of deionized water. Then heat the solution to 95°C and inject 0.4mL of phenylphosphonic dichloride into the flask. Then immediately cool the flask with an ice-water bath. After cooling the three-necked flask to room temperature in an ice-water bath, 40 mL of ethyl acetate was added to the flask, and the supernatant was removed by centrifugation (12000 rpm for 10 min). Then, 5 mL of n-hexane was added to disperse the nanocrystals, and the mixture was centrifuged again (2500 rpm for 4 min) to remove the precipitate, thus obtaining antimony-doped cesium indium chloride lead-free perovskite nanocrystals.

[0013] The product obtained by this invention is a high-quality indium-based lead-free perovskite luminescent material with a novel chemical composition (Cs4InCl7). Currently, research on indium-based halide perovskite nanocrystals for luminescence mainly focuses on Cs2AgInCl6, Cs2NaInCl6, Cs2InCl5-H2O, and Cs3InCl6, and some progress has been made. However, the preparation of high-quality indium-based perovskite nanocrystal luminescent materials remains a challenge.

[0014] This invention enables the production of antimony-doped cesium indium chloride (CIS) lead-free perovskite nanocrystals with high quantum yield through hot injection at relatively low temperatures. The cesium source used is cesium oleate, and the co-solvent tri-n-octylphosphine forms a clear precursor solution at 140°C. The deionized water added at 70°C does not completely evaporate when the solution reaches the injection temperature of 95°C, thus participating in the reaction. This is crucial for the formation of Cs₄InCl₇-Sb nanocrystals. Without the addition of deionized water, the Cs₃InCl₆-Sb phase is obtained.

[0015] This invention utilizes an antimony doping strategy to obtain Cs₄InCl₇-Sb nanocrystals with high quantum yield. Antimony acetate is added as the antimony source to a three-necked flask, and after injecting a chlorine source, antimony ions participate in the crystallization process, resulting in antimony-doped cesium indium chloride lead-free perovskite nanocrystals. Cs₄InCl₇ possesses isolated octahedral [InCl] prisms. 3- It belongs to the zero-dimensional (0D) structure and exhibits strong electron-phonon coupling. Antimony doping can achieve efficient yellow self-trapped exciton (STE) emission.

[0016] Compared with existing technologies, the technical advantages of this invention are as follows:

[0017] 1. The present invention yields an indium-based lead-free perovskite nanocrystal with a novel composition;

[0018] 2. This invention is an improved hot injection method with a lower injection temperature and shorter preparation time;

[0019] 3. This invention can effectively incorporate Sb into Cs4InCl7 to achieve bright yellow emission, and the resulting nanocrystals have a high luminescence quantum yield. Attached Figure Description

[0020] Figure 1 The X-ray diffraction (XRD) spectrum of the Cs4InCl7-Sb nanocrystals synthesized in this invention. The Cs4InCl7-Sb nanocrystals have a hexagonal crystal system with space group R-3m and exhibit good crystallinity.

[0021] Figure 2 Transmission electron microscopy (TEM) images and particle size distribution maps of undoped (a) and Sb-doped (b) Cs4InCl7 nanocrystals synthesized in this invention are shown. The obtained Cs4InCl7 nanocrystals exhibit a near-hexagonal morphology. The average particle size of the undoped Cs4InCl7 nanocrystals is 11.03 nm, while the average particle size of the Cs4InCl7 nanocrystals increases to 14.96 nm after Sb doping.

[0022] Figure 3 The absorption (abs, a), emission (PL, b), and excitation (PLE, b) spectra of the undoped and Sb-doped Cs4InCl7 nanocrystals synthesized in this invention are shown. The emission spectra obtained from excitation with different wavelengths of light are shown (c), and the excitation spectra obtained under monitoring with different wavelengths of light are shown (d). Compared to the undoped Cs4InCl7 nanocrystals, the Sb-doped Cs4InCl7 nanocrystals exhibit an additional absorption peak in their absorption spectrum (around 320 nm), which is attributed to the absorption of Sb ions. Furthermore, the undoped Cs4InCl7 nanocrystals exhibit almost no luminescence, while the Sb-doped Cs4InCl7 nanocrystals display a bright yellow emission (around 588 nm), with an optimal excitation wavelength of 345 nm. The emission spectra obtained from excitation with different wavelengths of light overlap, and the excitation spectra obtained under monitoring with different wavelengths of light also overlap, indicating that this yellow emission originates from self-trapped exciton emission.

[0023] Figure 4 Screenshot of the luminescence quantum yield test results of the Cs4InCl7-Sb nanocrystals synthesized in this invention. Its luminescence quantum yield is as high as 75.44%.

[0024] Figure 5The emission spectra (a), XRD patterns (b), and transmission electron microscopy (TEM) images (c) of indium-based perovskite nanocrystals synthesized in this invention with different H2O addition amounts are shown. As the H2O addition amount increases from 0 ml to 0.05 ml, the luminescence of the obtained indium-based perovskite nanocrystals changes from green emission (approximately 537 nm) to yellow emission (approximately 588 nm). When the H2O addition amount increases to 2.03, the obtained product has almost no emission intensity. According to the XRD patterns, when the H2O addition amount is 0 ml, the obtained indium-based perovskite nanocrystals are in the Cs3InCl6-Sb phase. As the H2O addition amount increases to 0.05 ml, the Cs3InCl6-Sb phase gradually transforms into the Cs4InCl7-Sb phase (Cs3InCl6-Sb belongs to...). The peak intensity of the (110) plane gradually decreases, while the peak intensity of Cs4InCl7-Sb gradually increases. When the amount of H2O added is 0 ml, the obtained Cs3InCl6-Sb nanocrystals exhibit an irregular morphology. When the amount of H2O added is 0.01 ml, the Cs3InCl6-Sb nanocrystals exhibit a cubic shape. As the amount of H2O added gradually increases, the nanocrystals exhibit a mixed morphology of cubic and hexagonal shapes, corresponding to the mixed phase of Cs3InCl6-Sb and Cs4InCl7-Sb nanocrystals. When the amount of H2O added increases to 0.05 ml, the nanocrystals exhibit a completely hexagonal shape, proving that the nanocrystals have all been transformed into the Cs4InCl7-Sb phase. When the amount of H2O added increases to 2.01 ml, the obtained nanocrystals exhibit a hollow morphology, indicating that excessive H2O addition will destroy the structure of Cs4InCl7-Sb, causing its emission to almost disappear. Detailed Implementation

[0025] The technical solution of the present invention will be further analyzed and explained through specific embodiments below.

[0026] Example 1:

[0027] Weigh 1.63 g of cesium carbonate into a three-necked flask, then add 20 mL of oleic acid. While evacuating the flask, heat the solution to 140 °C, then purge with nitrogen for 5 minutes until all the cesium carbonate and oleic acid have reacted, obtaining a cesium oleate precursor solution. Next, weigh 0.075 g of indium acetate into another three-necked flask, then add 2 mL of cesium oleate solution, 20 mL of 1-octadecene, 2 mL of oleic acid, 2 mL of oleylamine, and 0.5 mL of tri-n-octylphosphine. While evacuating the flask, heat the solution to 140 °C and maintain this temperature for 5 minutes. Then, place the three-necked flask in ice water to lower the solution temperature to 70 °C, then purge with nitrogen. Next, inject a mixture of 0.5 mL of isopropanol and 1.5 mL of deionized water. Heat the solution to 95 °C, then inject 0.4 mL of phenylphosphonic dichloro into the flask, and immediately cool the flask in an ice-water bath. After cooling the three-necked flask to room temperature in an ice-water bath, 40 ml of ethyl acetate was added to the flask, followed by centrifugation (12000 rpm for 10 min) and removal of the supernatant. Then, 5 ml of n-hexane was added to disperse the nanocrystals, followed by centrifugation (2500 rpm for 4 min) and removal of the precipitate to obtain antimony-doped cesium indium chloride lead-free perovskite nanocrystals.

[0028] Example 2:

[0029] Weigh 1.63 g of cesium carbonate into a three-necked flask, then add 20 mL of oleic acid. While evacuating the flask, heat the solution to 140 °C and purge with nitrogen for 5 minutes until all the cesium carbonate and oleic acid have reacted, obtaining a cesium oleate precursor solution. Next, weigh 0.075 g of indium acetate and 0.00075 g of antimony acetate into another three-necked flask, then add 2 mL of cesium oleate solution, 20 mL of 1-octadecene, 2 mL of oleic acid, 2 mL of oleylamine, and 0.5 mL of tri-n-octylphosphine. While evacuating the flask, heat the solution to 140 °C and maintain this temperature for 5 minutes. Then, place the three-necked flask in ice water to lower the solution temperature to 70 °C, purge with nitrogen, and then inject a mixture of 0.5 mL of isopropanol and 1.5 mL of deionized water. Heat the solution to 95 °C, then inject 0.4 mL of phenylphosphonic dichloro into the flask, and immediately cool the flask in an ice-water bath. After cooling the three-necked flask to room temperature in an ice-water bath, 40 ml of ethyl acetate was added to the flask, followed by centrifugation (12000 rpm for 10 min) and removal of the supernatant. Then, 5 ml of n-hexane was added to disperse the nanocrystals, followed by centrifugation (2500 rpm for 4 min) and removal of the precipitate to obtain antimony-doped cesium indium chloride lead-free perovskite nanocrystals.

[0030] Example 3:

[0031] Weigh 1.63 g of cesium carbonate into a three-necked flask, then add 20 mL of oleic acid. While evacuating the flask, heat the solution to 140 °C and purge with nitrogen for 5 minutes until all the cesium carbonate and oleic acid have reacted, obtaining a cesium oleate precursor solution. Next, weigh 0.075 g of indium acetate and 0.00375 g of antimony acetate into another three-necked flask, then add 2 mL of cesium oleate solution, 20 mL of 1-octadecene, 2 mL of oleic acid, 2 mL of oleylamine, and 0.5 mL of tri-n-octylphosphine. While evacuating the flask, heat the solution to 140 °C and maintain this temperature for 5 minutes. Then, place the three-necked flask in ice water to lower the solution temperature to 70 °C, purge with nitrogen, and then inject a mixture of 0.5 mL of isopropanol and 1.5 mL of deionized water. Heat the solution to 95 °C, then inject 0.4 mL of phenylphosphonic dichloro into the flask, and immediately cool the flask in an ice-water bath. After cooling the three-necked flask to room temperature in an ice-water bath, 40 ml of ethyl acetate was added to the flask, followed by centrifugation (12000 rpm for 10 min) and removal of the supernatant. Then, 5 ml of n-hexane was added to disperse the nanocrystals, followed by centrifugation (2500 rpm for 4 min) and removal of the precipitate to obtain antimony-doped cesium indium chloride lead-free perovskite nanocrystals.

[0032] Example 4:

[0033] Weigh 1.63 g of cesium carbonate into a three-necked flask, then add 20 mL of oleic acid. While evacuating the flask, heat the solution to 140 °C, then purge with nitrogen for 5 minutes until all the cesium carbonate and oleic acid have reacted, obtaining a cesium oleate precursor solution. Next, weigh 0.075 g of indium acetate and 0.006 g of antimony acetate into another three-necked flask, then add 2 mL of cesium oleate solution, 20 mL of 1-octadecene, 2 mL of oleic acid, 2 mL of oleylamine, and 0.5 mL of tri-n-octylphosphine. While evacuating the flask, heat the solution to 140 °C and maintain this temperature for 5 minutes. Then, place the three-necked flask in ice water to lower the solution temperature to 70 °C, then purge with nitrogen. Next, inject a mixture of 0.5 mL of isopropanol and 1.5 mL of deionized water. Heat the solution to 95 °C, then inject 0.4 mL of phenylphosphonic dichloro into the flask, and immediately cool the flask in an ice-water bath. After cooling the three-necked flask to room temperature in an ice-water bath, 40 ml of ethyl acetate was added to the flask, followed by centrifugation (12000 rpm for 10 min) and removal of the supernatant. Then, 5 ml of n-hexane was added to disperse the nanocrystals, followed by centrifugation (2500 rpm for 4 min) and removal of the precipitate to obtain antimony-doped cesium indium chloride lead-free perovskite nanocrystals.

[0034] Example 5:

[0035] Weigh 1.63 g of cesium carbonate into a three-necked flask, then add 20 mL of oleic acid. While evacuating the flask, heat the solution to 140 °C and purge with nitrogen for 5 minutes until all the cesium carbonate and oleic acid have reacted, obtaining a cesium oleate precursor solution. Next, weigh 0.075 g of indium acetate and 0.0075 g of antimony acetate into another three-necked flask, then add 2 mL of cesium oleate solution, 20 mL of 1-octadecene, 2 mL of oleic acid, 2 mL of oleylamine, and 0.5 mL of tri-n-octylphosphine. While evacuating the flask, heat the solution to 140 °C and maintain this temperature for 5 minutes. Then, place the three-necked flask in ice water to lower the solution temperature to 70 °C. Purge with nitrogen and then inject a mixture of 0.5 mL of isopropanol and 1.5 mL of deionized water. Heat the solution to 95 °C, then inject 0.4 mL of phenylphosphonic dichloro into the flask and immediately cool the flask in an ice-water bath. After cooling the three-necked flask to room temperature in an ice-water bath, 40 ml of ethyl acetate was added to the flask, followed by centrifugation (12000 rpm for 10 min) and removal of the supernatant. Then, 5 ml of n-hexane was added to disperse the nanocrystals, followed by centrifugation (2500 rpm for 4 min) and removal of the precipitate to obtain antimony-doped cesium indium chloride lead-free perovskite nanocrystals.

[0036] Example 6:

[0037] Weigh 1.63 g of cesium carbonate into a three-necked flask, then add 20 mL of oleic acid. While evacuating the flask, heat the solution to 140 °C, then purge with nitrogen for 5 minutes until all the cesium carbonate and oleic acid have reacted, obtaining a cesium oleate precursor solution. Next, weigh 0.075 g of indium acetate and 0.01125 g of antimony acetate into another three-necked flask, then add 2 mL of cesium oleate solution, 20 mL of 1-octadecene, 2 mL of oleic acid, 2 mL of oleylamine, and 0.5 mL of tri-n-octylphosphine. While evacuating the flask, heat the solution to 140 °C and maintain this temperature for 5 minutes. Then, place the three-necked flask in ice water to lower the solution temperature to 70 °C, then purge with nitrogen. Next, inject a mixture of 0.5 mL of isopropanol and 1.5 mL of deionized water. Heat the solution to 95 °C, then inject 0.4 mL of phenylphosphonic dichloro into the flask, and immediately cool the flask in an ice-water bath. After cooling the three-necked flask to room temperature in an ice-water bath, 40 ml of ethyl acetate was added to the flask, followed by centrifugation (12000 rpm for 10 min) and removal of the supernatant. Then, 5 ml of n-hexane was added to disperse the nanocrystals, followed by centrifugation (2500 rpm for 4 min) and removal of the precipitate to obtain antimony-doped cesium indium chloride lead-free perovskite nanocrystals.

[0038] Example 7:

[0039] Weigh 1.63 g of cesium carbonate into a three-necked flask, then add 20 mL of oleic acid. While evacuating the flask, heat the solution to 140 °C and purge with nitrogen for 5 minutes until all the cesium carbonate and oleic acid have reacted, obtaining a cesium oleate precursor solution. Next, weigh 0.075 g of indium acetate and 0.015 g of antimony acetate into another three-necked flask, then add 2 mL of cesium oleate solution, 20 mL of 1-octadecene, 2 mL of oleic acid, 2 mL of oleylamine, and 0.5 mL of tri-n-octylphosphine. While evacuating the flask, heat the solution to 140 °C and maintain this temperature for 5 minutes. Then, place the three-necked flask in ice water to lower the solution temperature to 70 °C. Purge with nitrogen and then inject a mixture of 0.5 mL of isopropanol and 1.5 mL of deionized water. Heat the solution to 95 °C, then inject 0.4 mL of phenylphosphonic dichloro into the flask and immediately cool the flask in an ice-water bath. After cooling the three-necked flask to room temperature in an ice-water bath, 40 ml of ethyl acetate was added to the flask, followed by centrifugation (12000 rpm for 10 min) and removal of the supernatant. Then, 5 ml of n-hexane was added to disperse the nanocrystals, followed by centrifugation (2500 rpm for 4 min) and removal of the precipitate to obtain antimony-doped cesium indium chloride lead-free perovskite nanocrystals.

[0040] Example 8:

[0041] Weigh 1.63 g of cesium carbonate into a three-necked flask, then add 20 mL of oleic acid. While evacuating the flask, heat the solution to 140 °C, then purge with nitrogen for 5 minutes until all the cesium carbonate and oleic acid have reacted, obtaining a cesium oleate precursor solution. Next, weigh 0.075 g of indium acetate and 0.006 g of antimony acetate into another three-necked flask, then add 2 mL of cesium oleate solution, 20 mL of 1-octadecene, 2 mL of oleic acid, 2 mL of oleylamine, and 0.5 mL of tri-n-octylphosphine. While evacuating the flask, heat the solution to 140 °C and maintain this temperature for 5 minutes. Then, place the three-necked flask in ice water to lower the solution temperature to 70 °C, purge with nitrogen, and then inject 0.5 mL of isopropanol. Next, heat the solution to 95 °C, then inject 0.4 mL of phenylphosphonic dichloro into the flask, and immediately cool the flask in an ice-water bath. After cooling the three-necked flask to room temperature in an ice-water bath, 40 ml of ethyl acetate was added to the flask, followed by centrifugation (12000 rpm for 10 min) and removal of the supernatant. Then, 5 ml of n-hexane was added to disperse the nanocrystals, followed by centrifugation (2500 rpm for 4 min) and removal of the precipitate to obtain antimony-doped cesium indium chloride lead-free perovskite nanocrystals.

[0042] Example 9:

[0043] Weigh 1.63 g of cesium carbonate into a three-necked flask, then add 20 mL of oleic acid. While evacuating the flask, heat the solution to 140 °C and purge with nitrogen for 5 minutes until all the cesium carbonate and oleic acid have reacted, obtaining a cesium oleate precursor solution. Next, weigh 0.075 g of indium acetate and 0.006 g of antimony acetate into another three-necked flask, then add 2 mL of cesium oleate solution, 20 mL of 1-octadecene, 2 mL of oleic acid, 2 mL of oleylamine, and 0.5 mL of tri-n-octylphosphine. While evacuating the flask, heat the solution to 140 °C and maintain this temperature for 5 minutes. Then, place the three-necked flask in ice water to lower the solution temperature to 70 °C. Purge with nitrogen and then inject a mixture of 0.5 mL of isopropanol and 0.01 mL of deionized water. Heat the solution to 95 °C, then inject 0.4 mL of phenylphosphonic dichloro into the flask and immediately cool the flask in an ice-water bath. After cooling the three-necked flask to room temperature in an ice-water bath, 40 ml of ethyl acetate was added to the flask, followed by centrifugation (12000 rpm for 10 min) and removal of the supernatant. Then, 5 ml of n-hexane was added to disperse the nanocrystals, followed by centrifugation (2500 rpm for 4 min) and removal of the precipitate to obtain antimony-doped cesium indium chloride lead-free perovskite nanocrystals.

[0044] Example 10:

[0045] Weigh 1.63 g of cesium carbonate into a three-necked flask, then add 20 mL of oleic acid. While evacuating the flask, heat the solution to 140 °C and purge with nitrogen for 5 minutes until all the cesium carbonate and oleic acid have reacted, obtaining a cesium oleate precursor solution. Next, weigh 0.075 g of indium acetate and 0.006 g of antimony acetate into another three-necked flask, then add 2 mL of cesium oleate solution, 20 mL of 1-octadecene, 2 mL of oleic acid, 2 mL of oleylamine, and 0.5 mL of tri-n-octylphosphine. While evacuating the flask, heat the solution to 140 °C and maintain this temperature for 5 minutes. Then, place the three-necked flask in ice water to lower the solution temperature to 70 °C. Purge with nitrogen and then inject a mixture of 0.5 mL of isopropanol and 0.03 mL of deionized water. Heat the solution to 95 °C, then inject 0.4 mL of phenylphosphonic dichloro into the flask and immediately cool the flask in an ice-water bath. After cooling the three-necked flask to room temperature in an ice-water bath, 40 ml of ethyl acetate was added to the flask, followed by centrifugation (12000 rpm for 10 min) and removal of the supernatant. Then, 5 ml of n-hexane was added to disperse the nanocrystals, followed by centrifugation (2500 rpm for 4 min) and removal of the precipitate to obtain antimony-doped cesium indium chloride lead-free perovskite nanocrystals.

[0046] Example 11:

[0047] Weigh 1.63 g of cesium carbonate into a three-necked flask, then add 20 mL of oleic acid. While evacuating the flask, heat the solution to 140 °C, then purge with nitrogen for 5 minutes until all the cesium carbonate and oleic acid have reacted, obtaining a cesium oleate precursor solution. Next, weigh 0.075 g of indium acetate and 0.006 g of antimony acetate into another three-necked flask, then add 2 mL of cesium oleate solution, 20 mL of 1-octadecene, 2 mL of oleic acid, 2 mL of oleylamine, and 0.5 mL of tri-n-octylphosphine. While evacuating the flask, heat the solution to 140 °C and maintain this temperature for 5 minutes. Then, place the three-necked flask in ice water to lower the solution temperature to 70 °C, then purge with nitrogen. Next, inject a mixture of 0.5 mL of isopropanol and 0.04 mL of deionized water. Heat the solution to 95 °C, then inject 0.4 mL of phenylphosphonic dichloro into the flask, and immediately cool the flask in an ice-water bath. After cooling the three-necked flask to room temperature in an ice-water bath, 40 ml of ethyl acetate was added to the flask, followed by centrifugation (12000 rpm for 10 min) and removal of the supernatant. Then, 5 ml of n-hexane was added to disperse the nanocrystals, followed by centrifugation (2500 rpm for 4 min) and removal of the precipitate to obtain antimony-doped cesium indium chloride lead-free perovskite nanocrystals.

[0048] Example 12:

[0049] Weigh 1.63 g of cesium carbonate into a three-necked flask, then add 20 mL of oleic acid. While evacuating the flask, heat the solution to 140 °C and purge with nitrogen for 5 minutes until all the cesium carbonate and oleic acid have reacted, obtaining a cesium oleate precursor solution. Next, weigh 0.075 g of indium acetate and 0.006 g of antimony acetate into another three-necked flask, then add 2 mL of cesium oleate solution, 20 mL of 1-octadecene, 2 mL of oleic acid, 2 mL of oleylamine, and 0.5 mL of tri-n-octylphosphine. While evacuating the flask, heat the solution to 140 °C and maintain this temperature for 5 minutes. Then, place the three-necked flask in ice water to lower the solution temperature to 70 °C, purge with nitrogen, and then inject a mixture of 0.5 mL of isopropanol and 0.05 mL of deionized water. Heat the solution to 95 °C, then inject 0.4 mL of phenylphosphonic dichloro into the flask, and immediately cool the flask in an ice-water bath. After cooling the three-necked flask to room temperature in an ice-water bath, 40 ml of ethyl acetate was added to the flask, followed by centrifugation (12000 rpm for 10 min) and removal of the supernatant. Then, 5 ml of n-hexane was added to disperse the nanocrystals, followed by centrifugation (2500 rpm for 4 min) and removal of the precipitate to obtain antimony-doped cesium indium chloride lead-free perovskite nanocrystals.

[0050] Example 13:

[0051] Weigh 1.63 g of cesium carbonate into a three-necked flask, then add 20 mL of oleic acid. While evacuating the flask, heat the solution to 140 °C and purge with nitrogen for 5 minutes until all the cesium carbonate and oleic acid have reacted, obtaining a cesium oleate precursor solution. Next, weigh 0.075 g of indium acetate and 0.006 g of antimony acetate into another three-necked flask, then add 2 mL of cesium oleate solution, 20 mL of 1-octadecene, 2 mL of oleic acid, 2 mL of oleylamine, and 0.5 mL of tri-n-octylphosphine. While evacuating the flask, heat the solution to 140 °C and maintain this temperature for 5 minutes. Then, place the three-necked flask in ice water to lower the solution temperature to 70 °C. Purge with nitrogen and then inject a mixture of 0.5 mL of isopropanol and 2.01 mL of deionized water. Heat the solution to 95 °C, then inject 0.4 mL of phenylphosphonic dichloro into the flask and immediately cool the flask in an ice-water bath. After cooling the three-necked flask to room temperature in an ice-water bath, 40 ml of ethyl acetate was added to the flask, followed by centrifugation (12000 rpm for 10 min) and removal of the supernatant. Then, 5 ml of n-hexane was added to disperse the nanocrystals, followed by centrifugation (2500 rpm for 4 min) and removal of the precipitate to obtain antimony-doped cesium indium chloride lead-free perovskite nanocrystals.

[0052] Example 14:

[0053] Weigh 1.63 g of cesium carbonate into a three-necked flask, then add 20 mL of oleic acid. While evacuating the flask, heat the solution to 140 °C and purge with nitrogen for 5 minutes until all the cesium carbonate and oleic acid have reacted, obtaining a cesium oleate precursor solution. Next, weigh 0.075 g of indium acetate and 0.006 g of antimony acetate into another three-necked flask, then add 2 mL of cesium oleate solution, 20 mL of 1-octadecene, 2 mL of oleic acid, 2 mL of oleylamine, and 0.5 mL of tri-n-octylphosphine. While evacuating the flask, heat the solution to 140 °C and maintain this temperature for 5 minutes. Then, place the three-necked flask in ice water to lower the solution temperature to 70 °C. Purge with nitrogen and then inject a mixture of 0.5 mL of isopropanol and 2.03 mL of deionized water. Heat the solution to 95 °C, then inject 0.4 mL of phenylphosphonic dichloro into the flask and immediately cool the flask in an ice-water bath. After cooling the three-necked flask to room temperature in an ice-water bath, 40 ml of ethyl acetate was added to the flask, followed by centrifugation (12000 rpm for 10 min) and removal of the supernatant. Then, 5 ml of n-hexane was added to disperse the nanocrystals, followed by centrifugation (2500 rpm for 4 min) and removal of the precipitate to obtain antimony-doped cesium indium chloride lead-free perovskite nanocrystals.

[0054] The basic physical properties of the nanocrystals obtained in the above embodiments are shown in Table 1 below.

[0055] Table 1 Properties of Sb-doped cesium indium chloride lead-free perovskite nanocrystals

[0056] serial number Photoluminescence spectral peak position (nanometer) Luminescent quantum efficiency (%) Example 1 - - Example 2 593.2 28.63 Example 3 588.8 57.23 Example 4 588.2 75.44 Example 5 587.8 68.56 Example 6 589.0 59.52 Example 7 586.4 33.21 Example 8 537.4 - Example 9 546.0 - Example 10 548.4 - Example 11 579.6 - Example 12 588.6 -

Claims

1. A method for preparing antimony-doped cesium indium chloride lead-free perovskite nanocrystals by a modified hot-injection method, characterized in that The method comprises the following steps: Step 1: weigh cesium carbonate into a reactor, then add oleic acid, heat the solution while vacuumizing and keep nitrogen flowing for a certain time until all the cesium carbonate and oleic acid are reacted to obtain a cesium oleate precursor solution; Step 2: weigh 0.075g indium acetate and 0.00075g-0.015g antimony acetate into another reactor, then add 2mL cesium oleate precursor solution, 20mL 1-octadecene, 2mL oleic acid, 2mL oleylamine and 0.3-0.5mL tri-n-octylphosphine, heat the solution to 140℃ while vacuumizing, keep for 5min, then place the three-neck flask in ice water to reduce the solution temperature to 70℃, then introduce nitrogen, then inject a mixed solution of isopropanol and deionized water, then heat the solution to 95℃, then inject 0.4mL phenylphosphonic dichloride into the flask, then immediately cool the flask with an ice water bath; after the reaction three-neck flask is cooled to room temperature with an ice water bath, add ethyl acetate to the flask, centrifuge to remove the supernatant, then add n-hexane to disperse the nanocrystals, centrifuge again and remove the precipitate to obtain antimony-doped cesium indium chloride lead-free perovskite nanocrystals; The mixed solution of isopropanol and deionized water is composed of 0.5mL isopropanol and 0.05-1.5mL deionized water. The antimony-doped cesium indium chloride lead-free perovskite nanocrystals are Sb-doped Cs4InCl7 nanocrystals.

2. The method of claim 1, wherein: In step 1, the cesium oleate precursor solution is prepared by dissolving 1.63g cesium carbonate in 20mL oleic acid.

3. The method of claim 2, wherein: In step 1, weigh 1.63g cesium carbonate into a reactor, then add 20mL oleic acid, heat the solution to 140℃ while vacuumizing, then keep nitrogen flowing until all the cesium carbonate and oleic acid are reacted to obtain a cesium oleate precursor solution.

Images