Structural\nReconfiguration\nvia Alternating Cation\nIntercalation of Chiral Hybrid Perovskites for Efficient Self-Driven\nX‑ray Detection

2D\nhybrid perovskites (HPs) have great potential for\nhigh-performance\nX-ray detection due to their strong radiation absorption and flexible\nstructure. However, there remains a need to explore avenues for enhancing\ntheir detection capabilities. Optimizing the detection performance\nthrough modification of their structural properties presents a promising\nstrategy. Herein, we explore the impact of modifying the organic spacer\nlayer in two distinct 2D layered HPs, namely, Ruddlesden–Popper\n(<i>R</i>-MPA)<sub>2</sub>PbBr<sub>4</sub> (<b>R-1</b>, <i>R</i>-MPA = methylphenethylammonium) and (<i>R</i>-MPA)EAPbBr<sub>4</sub> (EA = ethylammonium) (<b>R-2</b>) with alternating cation intercalation (ACI), on their X-ray detection\nperformance. The insertion of EA into <b>R-2</b> results in\na flatter inorganic skeleton, narrower spacing, and higher density\ncompared to <b>R-1</b>. This structural modification effectively\noptimizes carrier transport and X-ray absorption in <b>R-2</b>, enhancing the X-ray detection performance. Notably, <b>R-2</b> exhibits a polar structure with intrinsic spontaneous polarization,\ncontributing to a bulk photovoltaic of 0.4 V. This feature enables <b>R-2</b> single-crystal detectors to achieve self-driven X-ray\ndetection with a low detection limit of 82.5 nGy s<sup>–1</sup> under a 0 V bias. This work highlights the efficacy of the ACI strategy\nin structural modification and its significant effect on X-ray detection\nproperties, providing insights for the design and optimization of\nnew materials.