Efficient Optical Orientation and Slow Spin Relaxation in Lead-Free CsSnBr₃ Perovskite Nanocrystals

Spin properties of lead halide perovskites have recently received considerable research attention, because the strong spin–orbit coupling (SOC) enables facile optical orientation of spin-polarized states, a property particularly useful for information science and spintronics. The strong SOC, however, also limits the spin relaxation lifetime. Herein, we study optical orientation and spin relaxation in lead-free CsSnBr3 perovskite nanocrystals. The SOC of CsSnBr3 (∼0.43 eV) is 3.5-fold weaker than that of lead halide perovskites but is still strong enough to ensure efficient optical orientation. Meanwhile, the room-temperature spin lifetime is prolonged to 18 ± 2 ps, longer than the reported lifetimes of various lead halide perovskites, and it is likely limited by electron–hole exchange rather than SOC. These results demonstrate the strong potential of nontoxic tin halide perovskites for spin-related applications.