Sn‐Based Self‐Powered Ultrafast Perovskite Photodetectors with Highly Crystalline Order for Flexible Imaging Applications

Abstract Sn‐based perovskite materials are promising lead‐free alternatives in thin film photodetectors (PDs) for applications such as optical communications, night visions and biomedical near‐infrared imaging systems. However, constructing Sn‐based photodetectors with high sensitivity, ultrafast response, and good operation stability has been a challenge. Herein, the phenyl‐ethyl ammonium (PEA + ) additive is introduced in pristine FASnI 3 , which regulates the thin film growth, passivates the trap/defect states, prevents Sn 2+ /Sn 4+ oxidation, and releases the crystal strain. The Resulting FA 0.8 PEA 0.2 SnI 3 thin films exhibit highly crystalline order and flexibility. A self‐powered PD using FA 0.8 PEA 0.2 SnI 3 as the active layer demonstrates excellent responsivity of 0.262 W −1 , detectivity of 2.3 × 10 11 Jones. And it possesses the fastest rise and decay time of 25 µs and 42 µs as compared with the state‐of‐art Sn‐based perovskite PDs. The transient absorption spectroscopy analysis validates greatly reduced trapping states and defects of FASnI 3 with the PEA + film for ultrafast response. A flexible Sn‐based perovskite PD without any encapsulation in air continuously shows ultrafast responses after 10,000 bending cycles. Meanwhile, a flexible imaging system can be realized by a 5 × 5 PD array with good sensing results. This study shows great potential in nontoxic and ultrafast Sn‐based perovskite PDs for flexible imaging applications.