Enhanced Afterglow Performance of Carbon Dots via Surface Modification Engineering

Carbon dots (CDs) exhibit certain limitations in terms of afterglow emission intensity and water stability. Here, we present a strategy to enhance and stabilize the afterglow emission of CDs by sequentially modifying seed CDs with urea and 3-aminopropyltriethoxysilane. Compared to urea-modified CDs, the afterglow intensity of uCDs@SiO 2 was significantly enhanced by 25-fold, with the afterglow brightness increasing from 5.51 to 50.93 cd/m 2 under 5-watt illumination. More importantly, after calcination at 200 °C, uCDs@SiO 2 retain approximately 76% of their initial afterglow emission intensity in water solution over an 8-hour period. This retention is attributed to a dense SiO 2 matrix that mitigates oxygen-related surface defects and restricts non-radiative decay pathways. Finally, leveraging this robust afterglow, we demonstrate time-delay light-emitting diodes that continue to glow after power-off, as well as an information-encryption method based on selective quenching.