Quadra-Mode Luminescent Phosphors for Force/Thermo-Encoded Information Storage and Anticounterfeiting Applications

Multimode luminescent materials possess diverse optical characteristics and play crucial roles in photocommunication and information security. Force-induced mechanoluminescence, as a distinctive excitation mode, exhibits impressive capabilities in the field of anticounterfeiting and information storage. Here, we integrate mechanoluminescence with the conventional luminescence modes (including up-conversion luminescence, down-conversion luminescence, and thermoluminescence (TL)) within LiNbO3 via well-tuned codoping of Er3+ and Pr3+. LiNbO3:Pr3+/Er3+ exhibits excitation-dependent photoluminescence (PL), enabling tunable emission colors ranging from green to red, while it shows green up-converted PL emissions owing to the electronic transitions of Er3+ ions. Both TL and mechanoluminescence emissions are achieved by employing intertrap levels, where mechanical or thermal stimulation releases carriers that transfer energy to Pr3+ ions, resulting in red emissions. Moreover, an underlying competitive interaction between TL and mechanoluminescence is revealed, which can be leveraged for force/thermo-encored information storage. This unique feature positions LiNbO3:Pr3+/Er3+ as novel recordable information storage labels to monitor the freshness of perishable goods such as food and medicine. In addition, quadra-mode luminescence material LiNbO3:Pr3+/Er3+ provides multidimensional codes via emission color and distribution, indicating its significant potential in advanced anticounterfeiting technology.