Multiband MgGeO₃-Based Persistent Luminescent Nanophosphors for Dynamic and Multimodal Anticounterfeiting

Abstract

Persistent luminescence (PersL) materials are excellent candidates in the dynamic and multimodal anticounterfeiting field. Compared to commercially available micrometer-sized PersL phosphors, nanosized PersL materials could blend more easily with solvents and allow printing patterns with fine details. MgGeO 3 is one of the frequently employed lattice hosts for PersL phosphors. It can accommodate divalent ions such as Mn 2+ to produce deep-red PersL. To date, the only reported method of synthesizing nanosized Mn-doped MgGeO 3 (MGO:Mn) is the sol−gel method. The synthesis product has a wide particle size distribution and suffers severe aggregation. In this work, MGO:Mn nanorods are synthesized, for the first time, with a uniformly distributed morphology. These nanorods exhibit more intense and longer-lasting PersL. A detailed comparative study between the MGO:Mn nanorods developed in this work and the MGO:Mn particles prepared by the sol−gel method is performed to identify the origin of the improved PersL property. We also demonstrate that the afterglow duration of the MGO:Mn nanorods can be further modulated by adding co-dopants such as Yb 3+ , Eu 3+ , and Li + . The Yb 3+ dopant also introduces a second PersL emission band in the near-infrared region of ∼1000 nm. Using a combination of these MGO-based PersL nanorods, dynamic and multimodal anticounterfeiting can be achieved.