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.