Self‐Powered Perovskite/Si Bipolar Response Photodetector for Visible and Near‐Infrared Dual‐Band Imaging and Secure Optical Communication

Abstract Vertically stacked wavelength modulation bipolar response photodetectors are expected to be applied in various fields because they enable bipolar detection and transmission within one device and do not require harsh operating conditions. However, the as‐reported bipolar devices either need to change the detection mode (flipping the device or applying external bias) or have limited application effects. In this study, a self‐powered FAPbI 3 /silicon hybrid visible and near‐infrared bipolar response photodetector is reported, and the bipolar response is tuned by controlling the transmittance and interface contact of transparent electrodes. Moreover, unlike for photosensitive layers such as perovskites or organic compounds, the preparation of electrodes does not involve solvents, and array devices with different electrodes can be prepared in microregions without affecting adjacent regions. Then, an encrypted communication system that requires comprehensive consideration of the positive and negative states of different transparent electrode‐based devices caused by 650‐nm visible and 940‐nm near‐infrared transmission signals are designed, increasing the difficulty of decryption. A dual‐band spectral imaging system that does not require additional voltage driving by combining the reflection of visible light and the penetration ability of near‐infrared light is implemented, ensuring miniaturization and high integration of the visual imaging system.