Cage-Incorporation of Secondary Amine in Ruddlesden-Popper 2D Hybrid Perovskite with Strong Photoconductivity and Polarization Response

Two-dimensional (2D) Ruddlesden-Popper hybrid perovskites (RPHPs) have shown enormous potentials for photoelectric applications, owing to their advantages of structural diversity and unique physical properties. Despite extensive studies, the cage-incorporation of secondary amines (e.g. dimethylamine, DMA) to explore 2D RPHPs remains a great challenge. Here, we present a new member of 2D RPHPs, (BA)2(DMA)Pb2Br7 (1, BA+ = n-butylammonium), for which the organic DMA+ cations are enclosed in the perovskite cavities. The inorganic pervosktie sheets and organic BA+ spacing layers are arranged in the alternate packings, resembling that of 2D quantum-well motif. This feature is advantageous to the photoconductivity properties. Consequently, the crystal-based array detectors of 1 exhibit strong photodetection performances, including high detectivity (2.0 × 1011 Jones), large responsivity (31.1 mA/W), and fast response time (~8 μs). Moreover, its intrinsic 2D quantum-well structure endows significant anisotropy of conductivity and optical absorption, which account for the strong polarization response with a large dichroic ratio of ~1.43, falling in the range of other 2D RPHPs. These results reveal the potentials of 1 for photodetection, and simultaneously sheds light on the research of new candidates of 2D RPHPs.