Jia-Qin Liu, Yang Gao, Guo-An Wu, Xiao-Wei Tong, Chao Xie,* Lin-Bao Luo,* Lin Liang, Yu-Cheng Wu,*

Abstract: In this paper, we developed a highly sensitive near-infrared (NIR) photodetector by directly coating a layer of Cs-doped FAPbI3 perovskite film onto vertical Si nanowires (SiNWs) array. The as-assembled SiNWs array/perovskite core-shell heterojunction exhibits a typical rectifying behavior in the dark and distinct photoresponse characteristics under illumination. Owning to the remarkable photovoltaic effect, the heterojunction can work as a self-driven photodetector without an exterior power supply. Further photoresponse analysis reveals that the device is sensitive in a wide wavelength range with maximum sensitivity at ~850 nm. The responsivity and specific detectivity are estimated to be 14.86 mAW^-1 and 2.04×10¹⁰ Jones at zero bias, respectively, which can be improved significantly to 844.33 mAW-1 and 3.2×1011 Jones at an applied bias of -0.9 V. In addition, the present device also possesses distinct advantages of a large Ilight/Idark ratio exceeding 104, fast response speed with rise/decay times of 4/8 μs, and outstanding ambient stability.