Regulating structural asymmetry via fluorination engineering in hybrid lead bromide perovskites

Abstract

Here, we synthesized a pair of chiral two-dimensional lead bromide perovskites R-/S-(C₃H₇NF₃)₂PbBr₄ (1R/2S) using a H/F substitution strategy, which exhibit circular dichroism (CD) and circularly polarized luminescence (CPL) activity. Compared with one-dimensional non-centrosymmetric (C₃H₁₀N)₃PbBr₅ with local asymmetry obtained by isopropylamine, 1R/2S show a centrosymmetric inorganic layer despite the global chiral space group. Density functional theory calculations show that the formation energy of 1R/2S is lower than that of (C₃H₁₀N)₃PbBr₅, which implies the improved moisture stability in photophysical properties and CPL activity.