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.