Defect Passivation on Lead-Free CsSnI(3) Perovskite Nanowires Enables High-Performance Photodetectors with Ultra-High Stability

In recent years, Pb-free CsSnI(3) perovskite materials with excellent photoelectric properties as well as low toxicity are attracting much attention in photoelectric devices. However, deep level defects in CsSnI(3), such as high density of tin vacancies, structural deformation of SnI(6)(−) octahedra and oxidation of Sn(2+) states, are the major challenge to achieve high-performance CsSnI(3)-based photoelectric devices with good stability. In this work, defect passivation method is adopted to solve the above issues, and the ultra-stable and high-performance CsSnI(3) nanowires (NWs) photodetectors (PDs) are fabricated via incorporating 1-butyl-2,3-dimethylimidazolium chloride salt (BMIMCl) into perovskites. Through materials analysis and theoretical calculations, BMIM(+) ions can effectively passivate the Sn-related defects and reduce the dark current of CsSnI(3) NW PDs. To further reduce the dark current of the devices, the polymethyl methacrylate is introduced, and finally, the dual passivated CsSnI(3) NWPDs show ultra-high performance with an ultra-low dark current of 2 × 10(–11) A, a responsivity of up to 0.237 A W(−1), a high detectivity of 1.18 × 10(12) Jones and a linear dynamic range of 180 dB. Furthermore, the unpackaged devices exhibit ultra-high stability in device performance after 60 days of storage in air (25 °C, 50% humidity), with the device performance remaining above 90%. [Image: see text] SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s40820-022-00964-9.