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.