Abstract
Low-cost and low-temperature solution-processed halide perovskite single crystals show great potential in direct X-ray detection due to their large X-ray attenuation coefficient and efficient carrier generation and transport. Herein, we present solution-grown toxic lead-free Cu-doped Cs 3 Bi 2 Br 9 perovskite single crystals for highly sensitive X-ray detection and imaging. We fabricated a direct X-ray detector using a 2.5 mm thick Cu-Cs 3 Bi 2 Br 9 single crystal with a vertical structure of Au/ Cu-Cs 3 Bi 2 Br 9 /Au. Cu-Cs 3 Bi 2 Br 9 single crystal exhibit ultra-low dark current density of 2.5 pA mm -2 under an applied electric field of 8 V mm -1, which is significant as compared to other perovskite single crystals and high carrier mobility lifetime product (μτ) of 3.62 × 10 -4 cm 2 V -1 was obtained. A sensitivity of 264 μC {\text{G}}{{\text{y}}_{{\text{air}}}^{ - 1}{\text{c}}{{\text{m}}^{ - 2}} was achieved under irradiation of 30 kV X-ray and applied electric field of 40 Vmm -1 . The single crystal detector demonstrates an ultra-low limit of detection of 48 nGy/s, a fast response time (< 3 ms) with excellent operational and storage stability. We further studied the response of our X-ray detector under irradiation of clinical LINAC of 6 MV hard X-rays, which shows excellent dose monitoring capability.