Pyrazole‐Engineered Low‐Defect Tin Halide Perovskites for Ultraweak‐Light Imaging and Pixel‐Level Image Fusion

Abstract Tin halide perovskites have emerged as promising low‐toxicity and low‐cost semiconductors for broadband photodetection. Nevertheless, the drastic Sn 2+ oxidation and uncontrolled crystallization persistently compromise the perovskite film quality and device performance. Herein, potassium tri(1‐pyrazolyl) borohydride (KTPz), a molecule with a high dipole of 5 Debye, is strategically introduced into perovskite precursors to suppress Sn 2+ oxidation and fast crystallization via strong Lewis acid‐base interactions. The KTPz‐modified perovskite films exhibit preferred orientation and suppress non‐radiative recombination. The resulting perovskite photodetector attains state‐of‐the‐art performances across ultraviolet‐to‐infrared spectra, featuring remarkably low dark current (3.91 × 10 −10 A cm −2 ) and record‐high detectivity (3.23 × 10 13 Jones) among self‐powered near‐infrared photodetectors. Ultimately, a 62 × 62 imaging array integrating the perovskite photodetector with a silicon transistor backplane showcases real‐time imaging under ultralow irradiance (30 nW cm −2 ) and pixel‐level fusion of multispectral images, yielding a comprehensive analysis of the external contours and internal details of the target object. This work provides a strategy of utilizing pyrazole‐derived additives for simultaneously stabilizing Sn 2+ and modulating crystallization kinetics of tin halide perovskites, paving the way toward environment‐friendly and high‐quality imaging technologies.