Feng-Xia Liang, Lin Liang, Xing-Yuan Zhao, Lin-Bao Luo,* Yu-Hung Liu, Xiao-Wei Tong, Zhi-Xiang Zhang, J. C. Andrew Huang,*

Abstract:In this study, a sensitive and broadband perovskite photodetector was achieved by using crystalline topological insulator (TI) Bi₂Se₃ film as the electrode, which was synthesized by molecular beam epitaxy (MBE). The as-fabricated Bi₂Se₃-FA_0.85Cs_0.15PbI₃-Bi₂Se₃ photodetector exhibits apparent sensitivity to 650 nm illumination with and on/off ratio of 0.8×10⁵ and very good reproducibility. The responsivity, external quantum efficiency and specific detectivity areestimated to be 8.4 A/W, 1604% and 1.7×10¹³ jones, respectively, which are all better than not only the perovskite device using Au as electrode, but also than the majority of other perovskite materials based devices. It is interesting to find that the TI based perovskite photodetector also displays photoresponse to near infrared light with 980 nm due tocontribution fromTI Bi₂Se₃layer. We believe that thepresent TI based photodetector holds promise for broadband and high-performance optoelectronic applications in the future.