Carbon Dots as Afterglow Scintillators for Ultralong Afterglow and Low-Dose X-Ray Imaging

Afterglow scintillators have attracted significant attention because of their efficient triplet exciton utilization and radiative luminescence performance. However, achieving a high radioluminescence efficiency in carbon dots (CDs) based on low atomic number elements remains challenging. In this study, B-N trap states were introduced into the design of CDs afterglow composites, realizing ultralong afterglow emission and excellent scintillation properties. The B-N trap endowed the TpB-CDs@Urea composites with an ultralong afterglow lifetime of up to 10.72 s at room temperature, significantly exceeding those reported for phosphorescent materials. Moreover, TpB-CDs@Urea scintillators demonstrated high radio stability under x-ray excitation and exhibited a low radiation detection limit of 1.67 µGy s^-1, which allows efficient radiography imaging with a spatial resolution of 10.7 line pairs (lp) mm^-1. Based on these x-ray excitation radiation luminescence characteristics of TpB-CDs@Urea composites, their potential applications in x-ray photography technology were also demonstrated. Ultimately, the findings of this study provide a feasible principle for designing high-performance afterglow scintillator materials while expanding their application in fields such as detection and x-ray radiography.