Effects of 1,9-dibromnonane on the structural, photophysical properties and stability of cesium lead bromide perovskite nanocrystals

The CsPbBr3@Cs4PbBr6 nanocrystals (NCs) could be synthesized by multiple Cs-oleate injections as adding the 1,9-dibromnonane in the reaction solution. The 1,9-dibromnonane could provide Br- ions and the rich Br- ions effectively restrain the generation of CsBr. The Cs4PbBr6 wrapped around the CsPbBr3 NCs and the size of crystalline grain was increased with increasing the Cs-oleate as excess oleylamine. The quantum yield for 14S4DN reached to 99.3% due to the decrease of defects and the surface passivation of Cs4PbBr6. There are more oleylammonium bromide on the surface of CsPbBr3 NCs as synthesized with 1,9-dibromnonane. The ligand shell and the surface passivation of Cs4PbBr6 restrained the decomposition of surface, consequently improved the stability of moisture and light for CsPbBr3 NCs. When the CsPbBr3@Cs4PbBr6 NCs were immersed in water under UV light (365 nm) for 2 h, the PL intensity could retain 90.4%, while the 11S1 (traditional CsPbBr3 NCs) was only 10.9%. It indicated the stability of moisture and light for CsPbBr3 NCs were greatly improved, because Cs4PbBr6 NCs effectively passivated the surface of CsPbBr3 NCs and restrained the generation of traps states. (C) 2020 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.