Order-Disorder Transition Induced Dynamic Rashba Effect in 2D Halide Perovskites.

Two-dimensional (2D) hybrid organic-inorganic perovskites exhibit pronounced Rashba splitting, positioning them as promising candidates for spintronic applications. However, the underlying mechanism of inversion symmetry breaking and its impact on excitonic optical properties remains elusive. In this study, we investigate a series of 2D Ruddlesden-Popper perovskites and reveal that the order-disorder transition induced by phenyl-based cations triggers a dynamic Rashba effect. At the critical temperature, we observe a reduction in exciton recombination lifetime, an increase in circularly polarized photoluminescence, and a 3-fold enhancement in polarization by constructing a van der Waals heterostructure. Theoretical calculations indicate that local inversion symmetry breaking, driven by the slight displacement of Pb atoms, is the key mechanism underlying the dynamic Rashba effect. These findings establish the dynamic Rashba effect as a critical mechanism governing exciton dynamics, offering valuable insights into advancing spintronic and optoelectronic technologies based on 2D perovskites.