Realization of Tunable X-ray Detection in 2D Chiral-Polar Hybrid Perovskites

Metal halide perovskites have emerged as outstanding X-ray detection absorption candidates, benefiting from their excellent carrier mobility, strong radiation absorption capability, and ease of preparation. However, the realization of highly anisotropic X-ray detection with a tunable performance has rarely been investigated. Two-dimensional (2D) chiral-polar hybrid perovskites with the natural multiple quantum wells (MQWs) structure and the bulk photovoltaic effect (BPVE) present a prospective solution to meet the requirement of highly anisotropic X-ray detection. The pair of 2D chiral-polar perovskites has been synthesized in this work, termed (R-β-MPA)PAPbI₄ and (S-β-MPA)PAPbI₄ (1R and 1S, MPA = methylphenethylamine and PA = propylamine), aiming to achieve unique anisotropic X-ray detection resulting from the coupling of the distinctive MQWs structure and the BPVE. As expected, photodetectors based on high-quality single crystals of 1R result in a high dichroism ratio (I_max/I_min ≈ 7) for self-powered polarized-light detection. Strikingly, these photodetectors achieve high anisotropic ratios, reaching up to 9 under X-ray irradiation. This work reveals a strong correlation between X-ray detection performance and the coupling of specially oriented crystals with the BPVE, opening new possibilities for the realization of tunable X-ray detection.