Low-temperature synthesis of high-quality, high-stability, wide-bandgap perovskite films by solution methods is still challenging. Herein, large-scale wide-bandgap Cs 2 AgBiCl 6 (CABC) double perovskite films are synthesized by a vapor-phase anionexchange strategy. By dedicatedly designing an ultrathin TiO 2 modification layer between the substrate and double perovskites, highquality heterojunctions with matched energy band alignment are formed, contributing to a remarkably enhanced ON/OFF ratio of 2.4 × 10 4 (86 times) and a responsivity of 16 mA W −1 (12 times). Additionally, the ultraviolet photodetectors (UV PDs) exhibit an excellent UV detection limit of 1.18 μW cm −2 (20 nW), a broad linear dynamic range of 146 dB, and a high specific detectivity of 2.06 × 10 11 Jones, as well as long-term stability. Finally, we further demonstrate a weak UV imaging system using CABC UV PDs as imaging sensors. The system is capable of imaging weak UV signals as low as 2.94 μW cm −2 (50 nW). Our results provide a feasible approach for low-temperature fabrication of wide-bandgap perovskite UV PDs and explore the promising application for weak UV detection and imaging.
Light‐tracking systems and wide‐angle imaging are garnering increasing interest in the field of artificial intelligence due to their benefits to improve the light collection efficiency. Perovskite photodetectors have become the mainstream choice for their high adsorption coefficient, flex‐compatible properties, and low‐cost solution process. However, the fabrication of precise angle‐sensitive flexible detectors remains challenging due to the uncontrollable deposition of photosensitive layers. Herein, wide‐angle‐sensitive linear flexible perovskite photodetector arrays are successfully fabricated. The device exhibits a broad range of 144°, high‐resolution of 2.8°, and long‐term stability of 3000 cycles. As a proof‐of‐concept demonstration, a sunflower‐inspired light‐tracking system with adaptive following performance is illustrated. Furthermore, spatially encrypted imaging is achieved using linear perovskite photodetector arrays coupled with algorithms. This work confirms the superiority of flexible perovskite photodetectors in angle‐sensing and encryption imaging.
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