Unraveling Chiral Exciton g ex -Factor through Magneto-Optical Methods for Pure Blue Chiral Perovskite Nanocrystal Emitters

A chiral exciton represents a bound electron–hole pair for its interaction with circularly polarized light and is considerable in reduced-dimensional chiral perovskite nanocrystals (c-PNCs). A chiral exciton g ex -factor further decides spin-related excitonic sub-bands with responses to an external magnetic field, which leads to the field-manipulation of optical transitions and luminescence. It is thus very important to precisely quantify the chiral exciton g ex -factor. Herein, high-quality c-PNCs were synthesized to generate pure blue circularly polarized luminescence (CPL) at 464 nm. With a joint experimental and theoretical study, the magnetic field manipulation for CPL was studied in order to quantify the g ex -factor. It was further explored and verified by the magnetic circularly dichroism (MCD) spectroscopy. Our results suggest that the magnetic field acts as an effective tool for unraveling the microscopic origin of the magneto-optical activity (MOA) and revealing chiral excitonic photophysical properties such as the g ex -factor in the c-PNC system.