Continuous Nanomanufacturing of Inorganic Lead Halide Perovskite Nanocrystals with High-Concentration Precursors.

Abstract

The microscale flow preparation scheme has been widely used in the preparation of inorganic perovskite nanocrystals (NCs). It is considered to be the most promising method for large-scale production. Recently, it has been suggested that increasing the precursor concentration can further improve efficiency, but there is still a lack of understanding of high-concentration synthesis. Here, we develop a microscale flow synthesis scheme using high-concentration precursors, and the typical concentration value in the reaction phase reaches 0.035 mol/L using cesium acetate. The CsPbBr3 NCs with sharp photoluminescence (PL) at 515.7 nm can be obtained, and their PL quantum yield after post-treatment exceeds 90%. The effect of the molar ratio of Pb/Cs (Rm), reaction time, reaction temperature, and excess ligands on this flow reaction is studied. Several new phenomena are observed in our experiment. At 120 °C, some Cs4PbBr6 NCs exist in addition to the usual CsPbBr3 nanoplatelets. Excess ligands lead to the formation of numerous Cs4PbBr6 NCs with a bright green PL, and these NCs will spontaneously transform into a nonemission form in the film. Moreover, mixed-halide CsPbBrxI3-x NCs and CsPbI3 NCs are also prepared in this scheme, and then they are used to obtain LEDs in a range of colors.