Insight into the Synthesis of Colloidal Cesium Tin Halide Perovskite Nanocrystals: Size, Shape Control and Phase Transition

Abstract Colloidal nanocrystals (NCs) of fully inorganic perovskites have attracted much attention for their wide optoelectronic applications. Cesium tin halide (CsSnX3, X= Cl, Br, I) NCs possess the advantage of environmental friendliness. While there have been some reports on the synthesis of CsSnX3 NCs, the systematic study on turning the size and morphology through reaction temperature and surface ligands is lacking. In this report, CsSnX3 NCs were synthesized using a hot injection method with three precursors for Cs, Sn and X sources, respectively. We systematically altered the reaction temperature and ligands concentration to investigate their influence on the NC products. Upon decreasing the reaction temperature from 180 °C to 90 °C, the photoluminescence (PL) peak underwent a blue shift from 869 nm to 847 nm. Nanorods with a diameter as low as 3 nm were achieved at a lower reaction temperature, while cubic NCs with a size of 15 nm were achieved at the higher reaction temperature. The NCs show an increasing size and a wider distribution with the concentration of oleic acid (OA) and oleylamine (OAm) increasing. However, hexagonal Cs4SnI6 NCs other than CsSnI3 NCs will be produced when the OAm concentration is larger than 0.4 M. The study shed a light on the controllable synthesis of Sn-based perovskite NCs.