Modulating Chiral Molecular Configuration of Antioxidants for CsPb0.4Sn0.6I3 Perovskite Photodetectors

Abstract All-inorganic tin-lead (Sn−Pb) mixed-halide perovskites hold great potential for highly sensitive and broadband photodetectors. However, the performance of Sn−Pb perovskite photodetectors (PPDs) remains limited by Sn2+ oxidation and abundant interfacial defects. Herein, d-isoascorbic acid (DAA), which is a cost-effective chiral isomer of l-ascorbic acid (LAA), is introduced as a multifunctional additive into the perovskite precursor to break through these limitations. Based on experimental characterizations and density functional (DFT) calculations, it is proposed that the unique C5-R chiral configuration can trigger a conformational rearrangement within the molecular backbone of DAA, which creates an optimized planar configuration for −OH, C−O−C, and CO groups to facilitate robust multi-site synergistic coordination with these uncoordinated Pb2+, Sn2+, and I− ions. Benefiting from this stereochemical modulation, the DAA PPDs achieve a remarkably low dark current density of 6.72 × 10−9 A cm−2, a high responsivity of 0.37 A W−1, and a specific detectivity of 4.12 × 1012 Jones. Furthermore, the Sn−Pb PPDs exhibit rapid response times (96/110 μs) and enhanced resistance to environmental conditions. Our work highlights the role of chiral configuration in defect passivation and guides the design of effective perovskite additives.