Antisolvent-Assisted Synthesis of Bismuth Halide Perovskite Polycrystal Alloys for Sensitive X‑ray Detection

Perovskite X-ray detectors are promising in medical diagnosis and industrial inspection because of their high sensitivity and low limit of detection (LoD). Lead-free MA3Bi2I9 perovskite derivatives show good stability, environmental friendliness, and excellent electronic properties for sensitive X-ray detection. Here, we report the fabrication of MA3Bi2I9 X-ray detectors by a facile, high-throughput, and low-cost antisolvent-assisted synthesis (ASAS) method with a high product yield >90%. Electronic characteristics of MA3Bi2I9 were modulated by Cs alloying, leading to a high resistivity (1011 Ω cm) and a low dark carrier concentration (107 cm–3). As a result, (MA0.7Cs0.3)3Bi2I9-alloyed X-ray detectors show an LoD of 12.8 nGyair s–1 and a sensitivity of 130 μC Gyair –1 cm–2, outperforming that of a commercialized amorphous selenium (a-Se) detector. This study develops high-performance lead-free X-ray detectors with a robust, low-cost, and scalable fabrication process, which will pave the way for adopting polycrystalline MA3Bi2I9 in X-ray detectors.