The Preparation And Optical Properties Research Of All-inorganic Cesium Lead Halide Perovskite Nanocrystals

During the synthesis of all-inorganic perovskite nanocrystals,even small modifications to the synthesis scheme will have a strong impact on its morphology and optical properties.This property and its potential in the photovoltaic and photovoltaic fields application has attracted the interest of many researchers.Compared to organic and organic-inorganic hybrid perovskite nanocrystals,all-inorganic colloidal cesium lead halide perovskite nanocrystals have a simple synthesis method and excellent optical properties:high photoluminescence quantum yield（PLQY）,narrow and tunable emission wavelengths that have attracted widespread attention.Therefore,all-inorganic perovskite nanocrystals have been applied in solar cells,LEDs,low threshold lasers,single photon source photodetectors,fluorescent probes,biological imaging,and molecular tracing.Despite such rapid progress in material synthesis and device applications,research on the optical properties of all-inorganic perovskite nanocrystals has lagged far behind,and many issues related to it have not yet been resolved.For example,the photoluminescence quantum efficiency of perovskite nanocrystals depends on the synthesis method,and even small modifications to a given synthesis scheme will strongly affect its optical properties;The phase separation phenomenon of the mixed halide perovskite nanocrystals under laser excitation research on these aspects is still in its infancy.Their broad optical properties depend largely on the stoichiometric ratio of ions in the perovskite structure,the type of surface ligands and how the surface states are deactivated.This article starts with the preparation of basic materials and studies the optical properties related to the morphology and halogen composition of all-inorganic perovskite nanocrystals.For example,the optical properties of CsPbX3 nanocrystals are highly dependent on their shape and size,so CsPbX₃ nanocrystals with zero-dimensional quantum dots（QDs）,one-dimensional nanorods（NRs）,and two-dimensional nanoplatelets（NPLs）have developed rapidly.The specific research contents of this paper are as follows:Despite such rapid progress in material synthesis and device applications,the study of the optical properties of all-inorganic perovskite nanocrystals has lagged far behind,and many problems related to it have not been resolved.For example,the photoluminescence quantum efficiency of perovskite nanocrystals depends on the synthesis method,and even a small modification of a given synthesis scheme will strongly affect its optical performance;phase separation phenomenon occurs under continuous laser irradiation,the research on these aspects is still in its infancy.1.Briefly introduce the development of perovskite nanocrystals and understand their crystal structure and optical properties.2.Briefly introduce the commonly preparation methods of quantum dots.3.The ligand-assisted precipitation method was used to prepare the CsPbBr₃ nanosheets needed in this paper,and they were collectively characterized,and then use the single-photon detection system to measure at the single-particle level.（Trace and second-order photon-related measurements）to explain its luminescence mechanism.4.Synthesis of mixed halide perovskite Cs PbBr_xI_3-x-x nanocrystals by hot injection method,and study the phase separation under different Br and I doping ratios, different illumination times,different laser intensities,and different spin coating concentrations of mixed halide nanocrystals,and explain the mechanism of its phase separation.5.Finally,a brief description of the broad prospects of the luminescence properties of perovskite quantum dots will be made.