Stable and broadband photodetectors based on 3D/2D perovskite heterostructures with surface passivation
Yanfang Zha, Yun Wang, Yuhang Sheng, Xiaowei Zhang, Xinyue Shen, Fangjian Xing, Cihui Liu, Yunsong Di, Yingchun Cheng, Zhixing Gan
Abstract
Despite increasing research interest in two-dimensional (2D) perovskites, the stability and spectral response range of the photodetectors based on 2D perovskites are yet far from satisfactory. In this work, a semiconductor heterojunction is constructed based on dimethyl itaconate (DI) treated (BA)2PbI4 microplates and CsPb(Brx/I1−x)3 nanocrystals. The DI treatment not only passivates the defects but also blocks the moisture, resulting in improved stability and suppressed defect trapping. Meanwhile, the type-II heterojunctions facilitate the separation of electron–hole pairs. As a result, the photodetector based on the DI-(BA)2PbI4/CsPb(Brx/I1−x)3 exhibits a responsivity up to 209 nA/mW and a detectivity up to 5.9 × 108 Jones with a broad spectral response range of 400–600 nm. Furthermore, after storage in the ambient environment for 10 days, the responsivity retains about 70%, which is significantly ameliorated compared to the photodetector based on bare (BA)2PbI4 (drops more than 90%). Therefore, this work demonstrates that surface passivation and 2D/three-dimensional heterojunctions are promising strategies to improve responsivity, broaden spectral response range, and enhance stability of photodetectors based on 2D perovskites.