Tunable photoluminescence and persistent luminescence in Mn2+ doped germanate glass ceramic containing ZnAl2O4 nanocrystal for optical anticounterfeiting

Persistent luminescence (PerL) materials have garnered immense research interest on account of their distinctive luminescent features, and the rational design of such materials together with the elucidation of their underlying PerL mechanisms remain prominent research frontiers. Nevertheless, realizing tunable multicolor PerL within a single-phase material still poses a formidable challenge. Herein, we develop a novel Mn 2+ -doped germanate glass and glass ceramic (GC) with tunable PerL. In the pristine glass, abundant oxygen vacancy defects enable intense red PerL with a persistence time exceeding 420 s. After heat treatment, ZnAl 2 O 4 nanocrystals are homogeneously precipitated within the glass matrix, accompanied by the generation of new defects; as a result, the derived GC material exhibits green PerL that also persists over 420 s. Owing to divergent excitation spectral profiles of Mn 2+ centers residing in these two dissimilar coordination environments, the GC sample achieves reversible green-to-red PerL emission simply by modulating the excitation wavelength. Benefiting from such unique luminescence behaviors, the as-fabricated glass and GC show great promise for applications in emergency illumination, information display, and advanced optical anti-counterfeiting. Beyond reporting a facile strategy for multicolor PerL material construction, this work also provides fundamental guidance for defect engineering and emission color manipulation of future PerL systems.