Reducing defect of inorganic perovskite film by sulphur-containing Lewis base for robust photodetectors

Sluggish charge transfer in perovskite film induced by inherent defects such as uncoordinated Pb2+ undoubtedly hinders the rapid response of self-powered photovoltaic-typed detector. Based on interaction between Lewis acids and bases, herein, we employ thiourea molecule as a multifunctional Lewis base to significantly improve the quality of all-inorganic CsPbIBr2 perovskite film. After careful characterizations, the quality of perovskite film has been well regulated. Arising from the reduced defect and the reinforced the interfacial charge extraction owing to the strong interaction between uncoordinated Pb2+ ions and the -C = S groups in thiourea and the formation of hydrogen bond at perovskite/TiO2 interface, an enhanced responsivity of 0.335 A W−1 and specific detectivity of 3.92 × 1012 Jones has been achieved for the self-powered, carbon-electrode based photodetector, which is comparable to the state-of-the-art device based on CsPbIBr2 film. More importantly, the device free of encapsulation remains 82.8% of initial performance after storage over 56 days in ambient atmosphere, promoting the practical deployment of perovskite products.