Chiral defect-induced blue photoluminescence and circularly polarized luminescence of zero-dimensional Cs4PbBr6 perovskite nanocrystals

Chiral defect-induced strategy is employed to synthesize zero-dimensional (0D) chiral Cs4PbBr6 perovskite nanocrystals (NCs) with blue photoluminescence via a phase transition process. The chirality of the ground state of chiral Cs4PbBr6 perovskite NCs is confirmed by circular dichroism (CD) spectra, which shows the characteristic mirrored CD signals, behaving as a pair of enantiomers. Meanwhile, the obvious circularly polarized luminescence (CPL) response indicates that the chiral Cs4PbBr6 perovskite NCs are endowed with the chirality of the excited state. Furthermore, the UV–vis spectroscopy and electron paramagnetic resonance (EPR) data explicitly reveal that the CPL response originates from the chiral bromine vacancy (VBr). This work not only provides guidance to realize the CPL of 0D chiral perovskites but also gives insights into the structure–property relationship.