Color-tunable persistent luminescence in LiTa3O8 based phosphors for dynamic anticounterfeiting

Abstract

Rare earth-doped persistent luminescent (PersL) phosphors are excellent candidates for anticounterfeiting due to their superior properties, including various luminescent colors, multifarious luminescent modes, and dynamic emission intensity. For classical PersL phosphors, single-doped phosphor always shows monotonous luminescent color in different emission modes, such as photoluminescence (PL) and PersL, which limits the anticounterfeiting level to a low degree. To optimize the optical properties of phosphors for anticounterfeiting applications, constructing multiactivator-doped phosphors with polychromatic luminescence emissions can be a feasible strategy in practical material development. In this study, a novel multicolor PersL material, Pr3+/Tb3+-doped LiTa3O8, was reported for the first time, where the PersL color of Pr3+ in LiTa3O8 host was red whereas terbium(III) (Tb3+) ions exhibited green PersL color. Two improvement strategies were implemented, including substitution of tin(IV) (Sn4+) and codoping with gadolinium(III) (Gd3+), to enhance PersL properties by regulating distribution of traps. Gd3+ codoping strategy effectively improved PersL intensity while the Sn substitution strategy increased the initial PersL intensity by four-fold and the duration prolonged by 2.5-fold. Based on the results of luminescent properties, a multicolor tunable PersL material, LiTa3O8:0.7 %Pr3+ 1 % Tb3+, was synthesized and conceptually designed into a multimode anticounterfeiting application. Based on this scheme, prototype anticounterfeiting devices were developed, which could display the anticounterfeiting patterns in both dynamic and static states. Thus, this study fabricated a novel PersL material with multicolor light in different luminescent modes, thus deepening the fundamental understanding of PersL materials and diversifying the potential candidates of optical anticounterfeiting materials.