Unveiling chirality of perovskite quantum emitters with asymmetric magneto-optoelectronic responses

Metal halide perovskite quantum dots (QDs) are considered to have the lattice with inversion symmetry in the ideal case, but usually exhibit non-trivial spin polarization and asymmetric optoelectronical properties in experiments. We report an observation of chirality in the photoluminescence (PL) of CsPbBr3 QDs using the magneto optical spectroscopy. The QDs are fully encapsulated by SiO2 as a core/shell heterostructure, which stabilizes the PL emission and also enhances the lattice distortion. Asymmetric behaviors for the degree of circular polarization to the positive and negative magnetic field are observed from both bright and dark excitons in a single QD. The magnetic-optoelectronical responses demonstrate the exchange coupling between bright and dark excitons, which is consistent to the chiral features observed in experiment. Our work reveals that the non-trivial spin polarization in the emission of perovskite QDs arises from the mixture of excitonic states. The magnetic field manipulation of such effects in the encapsulation environment paves the way to apply them in novel asymmetric quantum devices.