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 atten-tion 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℃,50% humidity),with the device performance remaining above 90%.