Novel strategy of multidimensional information encryption via multi-color carbon dots aggregation-induced emission

Carbon dots (CDs) with aggregation-induced emission (AIE) have sparked significant interest in multidimensional anti-counterfeiting due to their exceptional fluorescence properties. However, the preparation of AIE CDs with multicolor solid-state fluorescence remains a formidable challenge due to its complicated construction. In the present work, a novel class of multicolor AIE CDs (M-CDs) were fabricated using selected precursor (salicylic acid, thiosalicylic acid, and 2,2'-dithiodibenzoic acid), with an eco-friendly, low-cost one-pot solvothermal method. In the dilute organic solution, M-CDs manifested blue emission, but upon aggregation in the presence of water, the red, yellow, green, and blue emissions were displayed due to the AIE effect. Structural analysis, coupled with theoretical calculations, revealed that the increase in the size of sp² domains would lower the E_g and cause a red-shift emission wavelength. Significantly, the continuous emission of M-CDs from blue to red can be utilized as ink for multimode printing, enabling the creation of a variety of school badges and quick response codes. These findings hold promising implications for multi-information encryption applications.