Carbon dots-engineered gold nanoclusters in silica enabled aqueous-phase fluorescence-phosphorescence dual-emission towards advanced luminescent anti-counterfeiting
Xiaojian Yan, Lin Wang, Wencheng Zhong, Ximeng Wang, Wenxing Gao, Li Shang
Abstract
Development of new anti-counterfeiting technology with dynamic optical signals has drawn great attention, but the use of multiple external stimulus or long-time light irradiation inevitably increases the operation complexity and limits the practical application. In this work, we report the design of new fluorescence-phosphorescence dual-emission materials based on carbon dots (CDs)-engineered gold nanoclusters (AuNCs) in silica for advanced luminescent anti-counterfeiting. In particular, co-encapsulation of phosphorescent CDs and fluorescent AuNCs by rigid silica matrix enables the construction of a dual-emission system (AuNCs/CDs@SiO<sub>2</sub>) in aqueous phase. The AuNCs/CDs@SiO<sub>2</sub> composite displayed significant fluorescence color change based on inner filter effect, as confirmed by in-depth spectral and photophysical characterization. Highly reversible and dynamic color switching between magenta fluorescence and green phosphorescence was easily achieved by simply switching on/off the ultraviolet (UV) irradiation. Potential utility of dual-emitting AuNCs/CDs@SiO<sub>2</sub> as novel dynamic anti-counterfeiting materials has been successfully demonstrated, including anti-counterfeiting ink, ink-free optical printing film, and information encryption. The present aqueous-phase fluorescence-phosphorescence dual-emission system exhibits two types of anti-counterfeiting mode without introducing external stimulus, increasing the difficulty of imitation and duplication. This work provides a straightforward and generable strategy to design advanced optical anti-counterfeiting materials by combining phosphorescent materials with other fluorophores via reasonable engineering strategy.