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.