Sensitive X-ray detection is crucial for medical diagnosis, industrial inspection and scientific research. The recently emerged hybrid lead halide perovskites have demonstrated low-cost fabrication and outstanding performance for direct X-ray detection whereas they all contain toxic Pb in a soluble form. Here, we report lead-free, stable and sensitive X-ray detectors using solution processed double perovskite Cs2AgBiBr6 single crystals and cold isostatically pressed Cs2AgBiBr6 wafers. For single crystals, we largely eliminated Ag+/Bi3+ disordering and improved the crystal resistivity through thermal annealing and surface treatment, resulting in a detector with minimum detectable dose rate down to 59.7 nGyair s-1, comparable to the latest record of 0.036 μGyair s-1 using CH3NH3PbBr3 single crystals. For wafers, we significantly suppressed the ionic migration and stabilized the dark current by in-situ forming two dimensional BiOBr, resulting in a detector with high voltage resistance. Our findings inform a new generation of highly efficient and low-cost X-ray detectors based on perovskite single crystals and wafers.
 W. C. Pan, J. Tang et. al. Cs2AgBiBr6 single-crystal X-ray detectors with a low detection limit. Nature Photonics 11.11 (2017): 726