Interfacial Engineering with Aluminum Oxide toward an Improved Self‐Powered Narrowband Visible‐Light Photodetection in Lead Halide Perovskite CH3NH3PbBr3/p‐Si Heterojunctions

Abstract Semiconductor heterojunctions consisting of lead halide perovskite (LHP) and silicon materials are important candidates for the fabrication of self‐powered visible‐light photodetectors. However, the interface recombination caused by interface trap states greatly deteriorates the performance of self‐powered photodetection, but fortunately, it can be suppressed by interfacial engineering. In this work, self‐powered narrowband visible‐light photodetection is demonstrated in the LHP CH 3 NH 3 PbBr 3 /p‐Si heterojunctions. Notably, the self‐powered photodetection performance is greatly enhanced by introducing an atomic‐layer‐deposition‐grown amorphous Al 2 O 3 thin interlayer. Electrical and optical properties measurements suggest that the Al 2 O 3 thin interlayer effectively passivates (reduces) the heterojunction interface trap states. On this basis, the CH 3 NH 3 PbBr 3 /Al 2 O 3 /p‐Si heterojunctions exhibit a decreased dark current and increased photocurrent simultaneously compared to CH 3 NH 3 PbBr 3 /p‐Si heterojunctions. Finally, a responsivity as high as 0.39 A W −1 and detectivity as high as 8.45 × 10 12 Jones under the bias voltage of 0 V are obtained, which are higher than most reported state‐of‐the‐art devices. The results reported in this work will provide valuable pathways for the fabrication of high‐performance self‐powered narrowband photodetectors based on LHP/Si heterojunctions.