Concentration-dependent and color-tunable room temperature afterglow of carbon dots@boric acid composites

Color-tunable room temperature afterglow (RTA) materials have become excellent candidates for a wide range of applications in information encryption and anti-counterfeiting. However, the achievement of color-tunable afterglow materials in a simple way remains a considerable challenge. In recent years, carbon dots (CDs) have attracted more and more attention in preparing metal-free long afterglow materials. Herein, a convenient and low-cost strategy with different doping concentrations for the preparation of carbon dots@boric acid (CDs@BA) composites with ultralong lifetime RTA has been proposed. Excitingly, the CDs@BA-(Ⅰ, Ⅱ, Ⅲ and Ⅳ) composites not only have ultralong afterglow lifetimes, but also exhibit color-tunable properties ranging from turquoise to deep yellow afterglow. In addition, these CDs@BA composites have been successfully used in the optical pattern design of safety exit signs and hazardous material signs. These findings may provide a new approach for the design of CDs-based nanomaterials with ultralong and color-tunable afterglow under ambient conditions.