Regulating structural asymmetry via fluorination engineering in hybrid lead bromide perovskites.

Here, we synthesized a pair of chiral two-dimensional lead bromide perovskites R -/ S -(C 3 H 7 NF 3 ) 2 PbBr 4 (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 (C 3 H 10 N) 3 PbBr 5 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 (C 3 H 10 N) 3 PbBr 5 , which implies the improved moisture stability in photophysical properties and CPL activity.