Biocompatible Metal-Free Perovskite Membranes for Wearable X-ray Detectors

Halide perovskites are emerging as promising materials for X-ray detection owing to their compatibility with flexible fabrication, cost-effective solution processing, and exceptional carrier transport behaviors. However, the challenge of removing lead from high-performing perovskites, crucial for wearable electronics, while retaining their superior performance, persists. Here, we present for the first time a highly sensitive and robust flexible X-ray detector utilizing a biocompatible, metal-free perovskite, MDABCO-NH₄I₃ (MDABCO = methyl-N'-diazabicyclo[2.2.2]octonium). This wearable X-ray detector, based on a MDABCO-NH₄I₃ thick membrane, exhibits remarkable properties including a large resistivity of 1.13 × 10¹¹ Ω cm, a high mobility-lifetime product (μ-τ) of 1.64 × 10^-4 cm² V^-1, and spin Seebeck effect coefficient of 1.9 nV K^-1. We achieve a high sensitivity of 6521.6 ± 700 μC Gy_air^-1 cm^-2 and a low detection limit of 77 nGy_air s^-1, ranking among the highest for biocompatible X-ray detectors. Additionally, the device exhibits effective X-ray imaging at a low dose rate of 1.87 μGy_air s^-1, which is approximately one-third of the dose rate used in regular medical diagnostics. Crucially, both the MDABCO-NH₄I₃ thick membrane and the device showcase excellent mechanical robustness. These attributes render the flexible MDABCO-NH₄I₃ thick membranes highly competitive for next-generation, high-performance, wearable X-ray detection applications.