Defect Passivation on Lead-Free CsSnI3 Perovskite Nanowires Enables High-Performance Photodetectors with Ultra-High Stability
Zheng Gao, Hai Zhou, Kailian Dong, Chen Wang, Jiayun Wei, Zhe Li, Jiashuai Li, Yongjie Liu, Zhao Jiang, Guojia Fang
Abstract
Abstract 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%.