Large Lead‐Free Perovskite Single Crystal for High‐Performance Coplanar X‐Ray Imaging Applications

Abstract Lead‐based (Pb) perovskite recently emerged as a promising photoelectric material for direct ionization radiation detection with outstanding performance. Unfortunately, its application is limited due to its toxicity caused by high Pb content, serious ion migration, poor crystallite quality, unsatisfactory reproducibility, high resistivity, and large fluctuation of electronic properties. Herein, a better substitute of lead‐free inch‐sized (34.3 mm × 34.3 mm × 13.1 mm) high‐quality halide (CH₃NH₃)₃Bi₂I₉ single crystal (MA₃Bi₂I₉ SC) is presented with higher resistivity, lower ion migration, and better stability. The coplanar detector fabricated using the MA₃Bi₂I₉ SC shows low dark noise current and outstanding X‐ray response including a high sensitivity of 872 μC Gy⁻¹ cm⁻², short response time of 266 μs, low detection limit of 31 nGy s⁻¹, good spatial resolution of 4.22 lp mm⁻¹, long‐term working stability, and excellent uniformity. Thanks to these excellent properties, the coplanar MA₃Bi₂I₉ SC X‐ray detector array shows high‐resolution X‐ray imaging. The present report may inspire development of next‐generation high‐energy radiation detection and imaging using lead‐free perovskite single crystals.