Realizing Stable and High‐Detectivity Near‐Infrared Photodetectors by Suppressing Interface Reaction Between Tin−Lead Perovskite and Nickel Oxide

Near‐infrared photodetectors based on narrow‐bandgap tin‐lead (Sn‐Pb) mixed perovskites hold great promise for next‐generation optoelectronics. However, their performance and stability are severely hampered by detrimental interfacial reactions at the NiO x /perovskite junction. Herein, we demonstrate an effective interface modification approach with multifunctional CuSCN interlayer to construct a high‐quality NiO x /perovskite heterojunction. The introduction of CuSCN can effectively suppressed interface reactions between NiO x and Sn‐Pb perovskite in two ways, by forming a physical spacer layer to avoid the direct contact and by forming coordinate covalent bond with Ni ≥3+ to reduce the highly reactive defects. Additionally, the CuSCN interlayer can not only optimize the energy level alignment with reduced hole transporting barrier and high electron injection barrier, but also promote the growth of perovskite films with superior crystallinity and preferred orientation. As a result, the fabricated near‐infrared photodetectors exhibit outstanding performance with a high responsivity of 0.497 A W −1 and a specific detectivity of 2.65 × 10 12 Jones at 940 nm. Remarkably, the devices based on CuSCN modified HTL demonstrate significantly enhanced operational stability in ambient air with high‐humidity (70%–95% RH). This work provides a versatile interface regulation approach for developing high‐performance and stable Sn‐Pb perovskite photodetectors toward a broader range of practical applications.