Excitation Wavelength-Dependent Dual-Mode Luminescence Emission for Dynamic Multicolor Anticounterfeiting

Luminescent materials have become prevalent in data communication and information security because of their special optical characteristics. Conventional luminescent materials generally exhibit unicolor emission and fixed excitation mode, resulting in decreased efficiency of anticounterfeiting applications. The development of an iridescent chameleon-like material that can change its emission color under different stimulations is a significant challenge. Here, we propose that Pb²⁺, Mn²⁺, and lanthanide cations (such as Y³⁺, Tb³⁺, Yb³⁺) co-doped in Na₂CaGe₂O₆ particles can be an effective tool for designing dual-mode anticounterfeiting materials based on their tunable fluorescence/persistent luminescence transformation and excitation wavelength-dependent emission. Ultimately, a proof-of-concept anticounterfeiting fabric is obtained by using the as-prepared phosphors and exhibits a dynamic multiple color response. This work exploits the possibility of developing a new class of multimode anticounterfeit materials, which would be almost impossible to mimic or counterfeit, providing a very high level of security.