Exciton Structure of Chiral Quasi‐2D Perovskite Revealed by Magnetic Field Effect

ABSTRACT Chiral hybrid perovskites have attracted significant research interest owing to their successful applications in spin‐optoelectronic devices. The introduction of chirality imparts novel chiroptical activities and chirality‐induced spin selectivity (CISS) into hybrid perovskite materials, enabling the manipulation of carrier spin polarization and circularly polarized luminescence. To further enhance the spin‐optoelectronic performance of chiral perovskites, a comprehensive understanding of their exciton structure and circularly polarized emission mechanism is essential. In this work, we study the magnetic field effects of photoluminescence (PL) and electroluminescence (EL) of a chiral perovskite material, where the spin‐polarized exciton generation and the spin mixing process among exciton energy levels occur. Additionally, circularly polarized transient absorption (CP‐TA) measurements uncover spin‐dependent exciton dynamics driven by an ultrafast energy and spin transfer process between the chiral 2D phase and the achiral 3D phase. These experimental observations are consistently explained by a model based on the chirality‐dependent exciton spin structure. By revealing the role of chirality in spin‐related light‐emitting processes, the model provides valuable insights for designing high‐performance spin‐optoelectronic devices based on chiral hybrid perovskites.