Multiple Interlayer Interactions Enable Highly Stable X-ray Detection in 2D Hybrid Perovskites

Metal halide perovskites have outperformed conventional inorganic semiconductors in direct X-ray detection due to their ease of synthesis and intriguing photoelectric properties. However, the operational instability caused by severe ion migration under a high external electric field is still a big concern for the practical application of perovskite detectors. Here, we report a 2D (BPEA)₂PbI₄ (BPEA = R-1-(4-bromophenyl)ethylammonium) perovskite with Br-substituted aromatic spacer capable of introducing abundant interactions, e.g., the molecular electrostatic forces between Br atoms and aromatic rings and halogen bonds of Br–I, in the interlayer space, which effectively suppresses ion migration and thus enables superior operational stability. Constructing direct X-ray detectors based on high-quality single crystals of (BPEA)₂PbI₄ results in a high sensitivity of 1,003 μC Gy^–1 cm^–2, a low detection limit of 366 nGy s^–1, and an ultralow baseline drift of 3.48 × 10^–8 nA cm^–1 s^–1 V^–1 at 80 V bias. More strikingly, it also exhibits exceptional operational stability under high flux, long-time X-ray irradiation, and large working voltage. This work shows an integration of multiple interlayer interactions to stabilize perovskite X-ray detectors, providing new insights into the future design of perovskite optoelectronic devices toward practical application.