Patent Application
20240035194
The present application claims the priority of Chinese Patent Application No. 202210919904.9, filed on Aug. 1, 2022, the contents of which are incorporated herein in their entirety by reference.
The present invention relates to the technical field of preparation of halide perovskite nanocrystals, and in particular, to a method for growing a halide perovskite nanocrystal through in-situ chemical vapor deposition.
Halide perovskite nanocrystals have excellent optical characteristics such as a high fluorescence quantum yield, a narrow emission half-peak width, and a continuously tunable light emission wavelength, which makes the halide perovskite nanocrystals become a focus of interest in scientific research and industry, and is one of the best candidates for the next generation of luminescent materials. However, since the halide perovskite is an ionic compound with soft lattice characteristics, it is susceptible to ion migration, phase transition, and decomposition in high humidity, high temperature, and ultraviolet irradiation environments, which greatly affects its stability. Therefore, preparing a halide perovskite nanocrystal structure with high stability has important practical significance for promoting the commercial application of perovskite materials.
The surface coating structure effectively isolates perovskite nanocrystals from the external environment, such that the stability of the perovskite against moisture, oxygen, heat, and light irradiation can be greatly improved. At present, direct growth of perovskite nanocrystals in the microporous channel of an inorganic porous material (for example, mesoporous silica, molecular sieve, zeolite, and the like) can effectively form the surface coating structure, thereby improving the stability of perovskite.
However, there are some key problems yet to be solved in the art of direct growth of perovskite nanocrystals in pores of a porous material. First, the current technology primarily concentrates on the green light-emitting CsPbBr3 nanocrystals, lacking attention to the red light-emitting CsPbI3 nanocrystals and blue light-emitting CsPbClxBr3, nanocrystals. Second, the common method of preparing perovskite nanocrystals in porous materials involves soaking the porous inorganic material in a liquid-phase precursor solution, which fills its pores with precursor ions. This method limits preparation efficiency and generates waste liquid, causing an increase in preparation costs. Third, the CsPbBr3 nanocrystals that are directly grown in the pores of the porous material lack a surface defect passivation mechanism, hindering the further improvement of their luminescence properties.
Therefore, there is a need to improve conventional technology.
An object of the present invention is to provide a method for growing halide perovskite nanocrystals through in-situ chemical vapor deposition, to solve the problems outlined in the above background art.
To attain the above object, the present invention provides the following technical solution: a method for growing a halide perovskite nanocrystal through in-situ chemical vapor deposition, comprising preparing a solid-phase precursor, and preparing a halide perovskite nanocrystal.
Further, the steps involved in the preparation of the solid-phase precursor are detailed below:
grinding and mixing cesium bromide and lead bromide powder to obtain a solid-phase precursor for preparing CsPbBr3 nanocrystal; and/or grinding and mixing cesium bromide, lead bromide, cesium chloride, and lead chloride powder to obtain a solid-phase precursor for preparing CsPbClxBr3-x mixed halogen nanocrystal; and/or grinding and mixing cesium iodide and lead iodide powder to obtain a solid-phase precursor for preparing CsPbI3 nanocrystal.
Further, the specific steps for preparing the halide perovskite nanocrystal are as follows:
grinding and mixing the solid-phase precursor and MCM-41 mesoporous molecular sieve; and then, heating the mixed powder in a nitrogen atmosphere and maintaining for 30-90 minutes, such that the solid-phase precursor is sublimated into a gaseous state and adsorbed into the pore channels of the mesoporous molecular sieve; and then, lowering the temperature with a cooling rate maintained at 3-10° C./min, such that the gas phase lead, cesium, and halogen atoms react in-situ in the pore channels of the molecular sieve and form the halide perovskite nanocrystal.
Compared with the prior art, the present invention has the following beneficial effects.
The present invention provides an all-solid-state precursor method for preparing halide perovskite nanocrystals, which eliminates the waste liquid generated by conventional liquid-phase precursor methods. The present invention greatly improves the luminescence properties of CsPbBr3 nanocrystals by passivating its surface defects with Cs4PbBr6 through the in-situ growth of Cs4PbBr6 and CsPbBr3 mixed phase within the pore channels of a molecular sieve. This leads to a fluorescent quantum yield of 90% or higher for the CsPbBr3 nanocrystals. By adjusting the halogen types in lead halide and cesium halide, it's possible to grow halide perovskite nanocrystals with different luminescence colors in the pore channels of molecular sieves. These include green light CsPbBr3 nanocrystals, blue light CsPbClxBr3-x nanocrystals, and red light CsPbl3 nanocrystals, which expands the optical application range for the technology of growing halide perovskite nanocrystals in molecular sieves.
The present disclosure will be further described below with reference to specific embodiments, and it should be noted that, without conflict, any combination of the embodiments or the technical features described below may form a new embodiment.
According to an embodiment of the present invention, a method for growing a halide perovskite nanocrystal through in-situ chemical vapor deposition is provided, and for a CsPbBr3 nanocrystal with green light emission, the specific experimental steps are as follows:
1. Grinding and mixing cesium bromide and lead bromide powders with the molar ratio of cesium bromide to lead bromide of 1:1, 1.5:1, and 2:1 to obtain three solid-phase precursors with different molar ratios.
2. Grinding and mixing the three solid-phase precursors and MCM-41 mesoporous molecular sieve with a mass ratio of 13:10; and then, heating the mixed powder in a nitrogen atmosphere, with temperature increase from room temperature to 565° C. and continuously heating at 565° C. for 40 minutes, the solid-phase precursor sublimates to a gaseous state and is adsorbed into the pore channels of the MCM-41 mesoporous molecular sieve; and then, lowering the temperature to room temperature, with a cooling rate maintained at 5° C./min, such that CsPbBr3 nanocrystals are formed through the in-situ reaction of bromine, lead and cesium atoms in the gas phase in the pore channels of MCM-41 molecular sieve during the cooling process.
Experimental analysis: The nanocrystal samples prepared from the three solid-phase precursors with different molar ratios were tested with X-ray diffraction. The detailed patterns are shown in
The nanocrystal samples prepared from the three solid-phase precursors with different molar ratios were tested with the light absorption spectrum and the fluorescence emission spectrum. The detailed spectra are shown in
The fluorescence quantum yield of the nanocrystals prepared from solid-phase precursors with different molar ratios was tested and detailed spectra are shown in
According to an embodiment of the present invention, it is provided a method for growing a halide perovskite nanocrystal through in-situ chemical vapor deposition, and for a CsPbClxBr3-x mixed halogen nanocrystal with blue light emission, the specific experimental steps are as follows:
1. Grinding and mixing cesium bromide, lead bromide, cesium chloride, and lead chloride powders with the molar ratio of 2:2:1:1, 2:1:1:0.5, and 2:0.6:1:0.3 to obtain three solid-phase precursors with different molar ratios.
2. Grinding and mixing the three solid-phase precursors and MCM-41 mesoporous molecular sieve with a mass ratio of 13:10; and then, heating the mixed powder in a nitrogen atmosphere, with temperature increase from room temperature to 575° C. and continuously heating at 575° C. for 40 minutes, the solid phase precursor sublimates to a gaseous state and is adsorbed into the pore channels of the MCM-41 mesoporous molecular sieve.; and then, lowering the temperature to room temperature, with a cooling rate maintained at 5° C./min, such that CsPbClxBr3-x mixed halogen nanocrystals are formed through the in-situ reaction of bromine, lead and cesium atoms in the gas phase within the pore channels of the MCM-41 molecular sieve during the cooling process.
Experimental analysis: The nanocrystal samples prepared from the three solid-phase precursors with different molar ratios were tested with the fluorescence emission spectrum. The detailed spectra are shown in
According to an embodiment of the present invention, it is provided a method for growing a halide perovskite nanocrystal through in-situ chemical vapor deposition, and for a CsPbI3 nanocrystal with red light emission, the specific experimental steps are as follows:
1. Grinding and mixing cesium iodide and lead iodide at a molar ratio of 1:1 to obtain a solid-phase precursor.
2. Grinding and mixing the solid-phase precursor and MCM-41 mesoporous molecular sieve with a mass ratio of 13:10; and then, heating the mixed powder in a nitrogen atmosphere, with temperature increase from room temperature to 450° C. and continuously heating at 450° C. for 60 minutes; and then, lowering the temperature to room temperature, with a cooling rate maintained at 5° C./min, such that CsPbI3 nanocrystals are formed in the pore channels of the MCM-41 molecular sieve during the cooling process.
Experimental analysis: The nanocrystal samples prepared from the solid-phase precursor were tested with the fluorescence emission spectrum. The detailed spectra are shown in
The basic principles, main features, and advantages of the present application are described above. It should be understood by those skilled in the art that the present application is not limited by the foregoing embodiments, and the embodiments and the description described above are merely the principles of the present application, and various changes and improvements will also be provided in the present application without departing from the spirit and scope of the present application, and these changes and improvements fall within the scope of the present application that is claimed. The scope of protection of the present application is defined by the appended claims and their equivalents.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202210919904.9 | Aug 2022 | CN | national |
