Ligand Mediated Transformation of Cesium Lead Bromide Perovskite Nanocrystals to Lead Depleted Cs4PbBr6 Nanocrystals
Zeke Liu,†,‡,∥ Yehonadav Bekenstein,‡,∥ Xingchen Ye,‡ Son C. Nguyen,‡ Joseph Swabeck,‡,∥ Dandan Zhang,‡,∥ Shuit-Tong Lee,† Peidong Yang,‡,§,∥,⊥ Wanli Ma,*,† and A. Paul Alivisatoss*,‡,§,∥,⊥
†Institute of Functional Nano & Soft Materials (FUNSOM), Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou, Jiangsu 215123, China
‡Department of Chemistry, University of California Berkeley, Berkeley, California 94720, United States
§Department of Materials Science and Engineering, University of California Berkeley, Berkeley, California 94720, United States
∥Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
⊥Kavli Energy NanoScience Institute, University of California Berkeley and Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
Lead halide perovskite nanocrystals (NCs) have emerged as attractive nanomaterials owing to their excellent optical and optoelectronic properties. Their intrinsic instability and soft nature enable a post-synthetic controlled chemical transformation. We studied a ligand mediated transformation of presynthesized CsPbBr3 NCs to a new type of lead−halide depleted perovskite derivative nanocrystal, namely Cs4PbBr6. The transformation is initiated by amine addition, and the use of alkyl-thiol ligands greatly improves the size uniformity and chemical stability of the derived NCs. The thermodynamically drive transformation is governed by a two-step dissolution−recrystallization mechanism, which is monitored optically. Our results not only shed light on a decomposition pathway of CsPbBr3 NCs but also present a method to synthesize uniform colloidal Cs4PbBr6 NCs, which may actually be a common product of perovskite NCs degradation.