Formation and Stability of Cs₂SnBr₆ Perovskite Nanocrystals from CsSn₂Br₅ Nanocubes

Abstract

Lead-free Sn(II) based, CsSn₂Br₅, perovskite nanocubes were synthesized using a modified hot-injection method by tuning the injection temperature and reaction conditions. The formation of Sn(IV) based, Cs₂SnBr₆, perovskite nanocrystals (PNCs) from CsSn₂Br₅ perovskite nanocubes was observed. X-ray diffraction measurements revealed that oxygen or water molecules in air gradually react with CsSn₂Br₅ perovskite nanocubes to form Cs₂SnBr₆ NCs. The stability of Cs₂SnBr₆ NCs was monitored by time-dependent absorption measurements. Both oxygen and water molecules react with the Cs₂SnBr₆ NCs to degrade, however water molecules appears largely to react with the NCs. The stability has been improved by dispersing the Cs₂SnBr₆ NCs in degassed anhydrous solvent.