Tin perovskite transistors stabilized through volatile coordination

Tin (Sn²⁺) halide perovskites are promising lead-free semiconductors for optoelectronic and electronic devices, owing to their tunable bandgaps and favourable charge transport^1,2. However, their practical implementation is fundamentally limited by an intrinsic redox instability at undercoordinated Sn²⁺ sites, which drives uncontrolled self-p-doping and rapid oxidative degradation^3,4. Here we introduce a volatile-assisted coordination strategy that reconstructs the perovskite surface through transient acetate coordination and volatilization, which transforms reactive SnI₂-terminated surfaces into chemically equilibrated and defect-mitigated interfaces. This surface reconstruction suppresses undercoordinated Sn-related trap states and stabilizes the local stoichiometry, thus enabling p-type transistors with robust transport characteristics, a near-zero threshold voltage and high on/off ratios exceeding 10⁸. More importantly, the reconstructed interface acts as a self-passivating and thermally resilient barrier, resulting in markedly enhanced environmental stability, with devices maintaining stable operation for over 1 month at 100 °C. These results establish volatile-assisted surface reconstruction as an effective method for defect equilibration in metastable semiconductors, and they provide a general strategy for enabling durable, device-grade functionality in Sn²⁺-based materials.