The Second Near-Infrared Window Persistent Luminescence for Anti-Counterfeiting Application

Persistent luminescence has shown great potential in anticounterfeiting technology benefiting from the feature of free background. However, current anticounterfeiting technology faces the challenges of low security and inconvenience, because these challenges are mainly based on visible light. Herein, we report the preparation of nanoscale Zn2Ga2Sn0.5O6:Yb3+-Ni2+ (ZGSO:Yb–Ni) phosphors with strong invisible persistent luminescence in the second near-infrared (NIR-II) window to meet the challenge. The nanoscale ZGSO:Yb–Ni phosphors (50–500 nm) were successfully prepared through the combination of a modified hydrothermal method and a subsequent annealing process. The resultant nanoparticles exhibit an intense NIR-II fluorescence at 1349 nm under the excitation of 254 nm light, and the persistent luminescence can last for ∼5 min after the excitation is switched off. A phosphor-based pattern was fabricated with resultant NIR-II nanopowders, and it shows high concealment, flexibility, and signal-to-noise ratio in the proof-of-concept experiment. These results demonstrate that ZGSO:Yb–Ni phosphors have great potential in anticounterfeiting applications.