Bionic Detectors Based on Low‐Bandgap Inorganic Perovskite for Selective NIR‐I Photon Detection and Imaging

Abstract

Abstract Fluorescence imaging with photodetectors (PDs) toward near‐infrared I (NIR‐I) photons (700–900 nm), the so‐called “optical window” in organisms, has provided an important path for tracing biological processes in vivo. With both excitation photons and fluorescence photons in this narrow range, a stringent requirement arises that the fluorescence signal should be efficiently differentiated for effective sensing, which cannot be fulfilled by common PDs with a broadband response such as Si‐based PDs. In this work, delicate optical microcavities are designed to develop a series of bionic PDs with selective response to NIR‐I photons, the merits of a narrowband response with a full width at half maximum (FWHM) of <50 nm, and tunability to cover the NIR‐I range are highlighted. Inorganic halide perovskite CsPb 0.5 Sn 0.5 I 3 is chosen as the photoactive layer with comprehensive bandgap and film engineering. As a result, these bionic PDs offer a signal/noise ratio of ≈10 6 , a large bandwidth of 543 kHz and an ultralow detection limit of 0.33 nW. Meanwhile, the peak responsivity ( R ) and detectivity ( D *) reach up to 270 mA W −1 and 5.4 × 10 14 Jones, respectively. Finally, proof‐of‐concept NIR‐I imaging using the PDs is demonstrated to show great promise in real‐life application.