Air‐Stable Self‐Powered Photodetectors Based on Lead‐Free CsBi3I10/SnO2 Heterojunction for Weak Light Detection

Abstract Lead halide perovskites (LHPs) have been widely investigated in photodetection applications owing to their intriguing optoelectronic properties. However, the application of LHPs‐based photodetectors (PDs) is hindered because of the toxicity of lead and instability in ambient air. Here, an air‐stable self‐powered photodetector is designed based on all‐inorganic lead‐free CsBi 3 I 10 /SnO 2 heterojunction. The device exhibits broad spectral response in both UV and visible light, fast response on µs scale, and decent long‐term stability. The device holds a faster response speed ( t r /t d = 7.8/8.8 µs), among the best reported self‐powered lead‐free perovskites photodetectors. More importantly, the device can display obvious photoresponses even under ultra‐weak light intensity as low as 10 pW cm –2 , showing better weak‐light sensitivity than previously reported lead‐free perovskites photodetectors, to the best of our knowledge. Moreover, the device holds good air stability in the 73 days test without encapsulation. These results suggest that CsBi 3 I 10 /SnO 2 ‐based self‐powered PDs with high photodetection capability possess enormous potential in stable and broadband PDs for weak light detection in the future.