Relaxation and Diffusion of the Spin-Polarized Excitons in Quasi-2D Dion-Jacobson Phase Perovskites

Metal-halide perovskites have shown potential for opto-spintronic applications. However, our fundamental understanding of spin diffusion and transport dynamics in these materials remains limited. In this study, we investigate the spin relaxation and diffusion dynamics in a two-dimensional Dion-Jacobson perovskite (AMP)PbI₄ using steady-state and time-resolved circularly polarized photoluminescence techniques. At room temperature, we observed a circular polarization degree of 52% in photoluminescence and a spin relaxation time exceeding 20 ns. Temperature-dependent studies reveal a strong correlation between the circular polarization degree, spin relaxation time, and the thermally enhanced Rashba effect, which stabilizes spin coherence at elevated temperatures. Spatial and temporal imaging of spin-polarized excitons demonstrate that the spin diffusion length and coefficient closely match those of excitons, indicating that spin polarization is primarily transmitted through exciton diffusion. This exciton-mediated spin transport mechanism, combined with high spin polarization and extended spin relaxation times, demonstrates the potential of two-dimensional perovskites for room-temperature spintronic devices.