Authors: Huayang Li, Yuhong He, Weijun Li, Tong Lu, Mingrui Tan, Wei Wei, Bai Yang, Haotong Wei
Published: 2022-09-19
Source: Full article
AbstractHalide perovskites with various compositions are potential candidates in low‐dosage X‐ray detection due to their large sensitivity and tunable optoelectronic properties. Here, cations engineering induced dimensional evolution of halide perovskites between 0D, 2D, and 3D is reported. Centimeter‐sized 2D lead‐free perovskite single‐crystal of 4‐fluorophenethylammonium antimony iodide (FPEA3SbI6) is synthesized. In contrast to the 0D phenethylammonium antimony iodide (PEA3Sb2I9), face‐shared [Sb2I9]3– of the bi‐octahedral structure of PEA3Sb2I9 is split into corner‐shared [SbI6]3– by intermolecular interactions and steric hindrance of FPEA+ ions in 2D FPEA3SbI6. Two Sb3+ ions share three octahedral [SbI6]3–, leaving one‐third of Sb3+ vacancies in the framework of FPEA3SbI6. Furthermore, Sn2+ ions can be filled into the vacancies to form continuous 2D frameworks to tune the anisotropic conductivity and device sensitivity to hard X‐rays. The dimensional evolution of perovskite single‐crystals from 3D to 2D or 0D to 2D maximizes the signal/noise ratio to facilize the adjustability of detection limit in hard X‐ray detection, which is determined by both device sensitivity and device noise current. A record low detection limit coefficient of 0.65 is achieved in the 2D FPEA3SbSn0.5I7 single‐crystal sample, which results from selective charges collection over mobile ions/noise current in the 2D perovskite structure.