Multilevel Static-Dynamic Anticounterfeiting Based on Stimuli-Responsive Luminescence in a Niobate Structure.

Anticounterfeiting is a highly required technique to protect the product and the consumer rights in the modern society. The conventional luminescent anticounterfeiting is based on downconversion luminescence excited by an ultraviolet light, which is easy to be faked. In this work, we realized six luminescent modes in a niobate-based structure (LiNbO:RE, RE = Pr, Tm, Er, Yb), in which photostimulated luminescence of LiNbO:Pr, and upconversion luminescence color evolution of LiNbO:Er were first presented. Based on the above luminescent modes of LiNbO:RE, multilevel anticounterfeiting devices were developed. By employing mechanoluminescence and persistent luminescence, we achieved dual-mode anticounterfeiting that could display the luminescent patterns without any direct irradiation. In addition, another dual-mode anticounterfeiting based on photostimulated luminescence and upconversion luminescence excited by a near-infrared light was realized, which could display the anticounterfeiting patterns in both static and dynamic states. To obtain an even higher anticounterfeiting level, downconversion luminescence, thermoluminescence, photostimulated luminescence, and upconversion luminescence were simultaneously applied in a food trademark. This four-mode anticounterfeiting trademark could not only show a static-dynamic luminescence that is hard to be faked but also allow consumers to distinguish the food freshness. The presented multilevel anticounterfeiting strategies could be employed to resolve the counterfeit issues in various fields.