Intrinsic Defect Tolerance in Inorganic Tin–Lead Perovskites

Experimentally, inorganic tin–lead (Sn–Pb) perovskites exhibit an extremely short carrier lifetime of mere nanoseconds, primarily attributed to strong nonradiative recombination induced by high-density defects. This has led to the belief that they are highly defect-sensitive. Here, we argue that inorganic Sn–Pb perovskites are intrinsically defect-tolerant. We substantiate this claim by performing rigorous first-principles calculations for a prototypical composition CsSn_0.5Pb_0.5I₃. Our results show that this material possesses an ultralong nonradiative lifetime of 10 μs, even under the assumption of a high defect concentration of 10¹⁶ cm^–3. The alteration in band edge energies arising from the mixing of CsSnI₃ and CsPbI₃ is proven to contribute to the remarkable defect tolerance. We ascribe the poor photoelectric performance observed in inorganic Sn–Pb perovskites to inadequate miscibility of their components. This study reveals the inherent superior properties of inorganic Sn–Pb perovskites that have thus far remained unrecognized by the research community and suggests that achieving phase-pure mixing systems is crucial to fully exploit their untapped potential.