The method comprises the following steps: mixing cesium
carbonate, lead
halide, 1-
octadecene and an organic ligand, then carrying out gradual heating, fully utilizing the
solubility difference of raw materials under a low-temperature condition, firstly forming an intermediate phase Cs4PbX6 under the low-temperature condition, and carrying out one-pot in-situ phase transformation on the intermediate phase Cs4PbX6 to obtain the all-
inorganic lead halide perovskite nanocrystal. And reacting the intermediate phase with gradually dissolved PbX2 at a relatively high temperature to form the CsPbX3
nanocrystal in situ. According to the invention, through the formation of the intermediate phase, the formation process of the CsPbX3
nanocrystal is delayed, the growth process of the nanocrystal is effectively regulated and controlled, and the
perovskite nanocrystal with excellent
fluorescence performance can be obtained. The method has the advantages of simple preparation process, cheap and easily available raw materials, mild
reaction conditions, no need of
inert protective
atmosphere, good reproducibility, easy batch preparation and the like, and can promote large-scale preparation and commercial application of the
perovskite nanocrystals.