Cs2AgBiBr6 single-crystal X-ray detectors with a low detection limit

Sensitive X-ray detection is crucial for medical diagnosis, industrial inspection and scientific research. The recently described hybrid lead halide perovskites have demonstrated low-cost fabrication and outstanding performance for direct X-ray detection, but they all contain toxic Pb in a soluble form. Here, we report sensitive X-ray detectors using solution-processed double perovskite Cs 2 AgBiBr 6 single crystals. Through thermal annealing and surface treatment, we largely eliminate Ag + /Bi 3+ disordering and improve the crystal resistivity, resulting in a detector with a minimum detectable dose rate as low as 59.7 nGy air  s −1 , comparable to the latest record of 0.036 μGy air  s −1 using CH 3 NH 3 PbBr 3 single crystals. Suppressed ion migration in Cs 2 AgBiBr 6 permits relatively large external bias, guaranteeing efficient charge collection without a substantial increase in noise current and thus enabling the low detection limit.