Extreme gamma-ray radiation hardness and high scintillation yield in perovskite nanocrystals

Radiation detection is of utmost importance in fundamental scientific research, as well as medical diagnostics, homeland security, environmental monitoring and industrial control. Lead halide perovskites (LHPs) are attracting growing attention as high-atomic-number materials for next-generation scintillators and photoconductors for ionizing radiation detection. To unlock their full potential as reliable and cost-effective alternatives to conventional materials, it is necessary for LHPs to conjugate high scintillation yields with emission stability under high doses of ionizing radiation. To date, no definitive solution has been devised to optimize the scintillation efficiency and kinetics of LHPs and nothing is known of their radiation hardness for doses above a few kilograys, to the best of our knowledge. Here we demonstrate that CsPbBr3 nanocrystals exhibit exceptional radiation hardness for gamma-radiation doses as high as 1MGy. Spectroscopic and radiometric experiments highlight that despite their defect tolerance, standard CsPbBr3 nanocrystals suffer from electron trapping in dense surface defects that are eliminated by post-synthesis fluorination. This results in >500% enhancement in scintillation efficiency, which becomes comparable to commercial scintillators, and still retaining exceptional levels of radiation hardness. These results have important implications for the widespread use of LHPs in ultrastable and efficient radiation detectors.