Defect mitigation in lead-free Cs₃Bi₂I₉ single crystals for high performance X-ray detection and imaging

Cs ₃ Bi ₂ I ₉ single crystals has attracted increasing attention in perovskite X-ray detectors due to its low cost, nontoxicity, high stability and low detection limit. With the gradual improvement of device performance, the growth of high-quality, low-defect single crystals becomes increasingly crucial. In this work, we developed a polypropylene glycol nucleation control strategy for the effective growth of Cs ₃ Bi ₂ I ₉ single crystals with fewer defects. The X-ray detectors prepared by this strategy exhibit excellent detection and imaging performance, reaching a sensitivity of 173.9 μC·Gy _air ^-1 ·cm ^-2 at 40 V·mm ^-1 and a detection limit of 1.57 μGy _air ·s ^-1 , and showcasing sharp imaging ability. This research contributes to the advancement of next-generation X-ray detection.