Ultrafast scintillation at room temperature achieved in CsPbCl3-based single crystals through Br over-doping

Abstract

Owing to their excellent photo-electron conversion efficiency and sub-nanosecond scintillation decay time at low temperatures, all-inorganic halide perovskite CsPbCl₃ single crystals demonstrate potential for application in ultrafast scintillation. However, sub-nanosecond scintillation from CsPbCl₃ single crystals at room temperature has not been achieved to date. To address this issue, the strategy of Br over-doping was proposed to realize sub-nanosecond scintillation. In this work, high-quality, Br over-doped CsPbCl₃:Br_x (x = 0.006, 0.014, and 0.020) single crystalline ingots with a diameter of 16 mm were grown using the vertical Bridgman method. Compared to the undoped CsPbCl₃ single crystal, the scintillation decay time of CsPbCl₃:Br_0.020 decreases from 6.011 to 0.630 ns, reduced by one order of magnitude. The trap state density decreases from 1.421 × 10⁸ to 1.381 × 10⁷ cm⁻³, indicating that Br over-doping passivates trap states leading to a slow decay component. Second, Br over-doping causes a great increase in the exciton binding energy from 60.11 to 77.53 meV, indicating a much higher exciton recombination rate. The two mechanisms could synergistically result in sub-nanosecond scintillation at room temperature. The ultrafast scintillation decay time suggests that CsPbCl₃:Br_x crystals have great potential in fields such as positron emission computed tomography, clinical medical imaging and fast X-ray imaging.