Structural Reconfiguration via Alternating Cation Intercalation of Chiral Hybrid Perovskites for Efficient Self-Driven X-ray Detection

2D hybrid perovskites (HPs) have great potential for high-performance X-ray detection due to their strong radiation absorption and flexible structure. However, there remains a need to explore avenues for enhancing their detection capabilities. Optimizing the detection performance through modification of their structural properties presents a promising strategy. Herein, we explore the impact of modifying the organic spacer layer in two distinct 2D layered HPs, namely, Ruddlesden-Popper (R-MPA)₂PbBr₄ (R-1, R-MPA = methylphenethylammonium) and (R-MPA)EAPbBr₄ (EA = ethylammonium) (R-2) with alternating cation intercalation (ACI), on their X-ray detection performance. The insertion of EA into R-2 results in a flatter inorganic skeleton, narrower spacing, and higher density compared to R-1. This structural modification effectively optimizes carrier transport and X-ray absorption in R-2, enhancing the X-ray detection performance. Notably, R-2 exhibits a polar structure with intrinsic spontaneous polarization, contributing to a bulk photovoltaic of 0.4 V. This feature enables R-2 single-crystal detectors to achieve self-driven X-ray detection with a low detection limit of 82.5 nGy s^-1 under a 0 V bias. This work highlights the efficacy of the ACI strategy in structural modification and its significant effect on X-ray detection properties, providing insights for the design and optimization of new materials.