A multi-color persistent luminescent phosphor Ca3Al2Ge3O12:Re3+(Re3+=Tb3+, Pr3+, Dy3+) for dynamic anti-counterfeiting

Anticounterfeiting is a highly required technique to protect the product and consumer rights in modern society. The traditional anti-counterfeiting luminescent materials are generally presented as monochromatic emission and fixed excitation modes. Here, rare earth ions (Re3+=Tb3+, Pr3+, Dy3+) doped Ca3Al2Ge3O12 can produce the novel multi-modal and multi-color long afterglow anti-counterfeit material. When adjusted the Tb3+ concen-tration, the different trap types, the trap concentrations and trap depths were formed, leading to the different afterglow of Ca3Al2Ge3O12:Tb3+ duration from 4 to 24 h. The long afterglow color of Ca3Al2Ge3O12:Pr3+ can turn from red to green by the cross-relaxation process with changing the Pr3+ ions concentration. The afterglow color of Ca3Al2Ge3O12:Dy3+ can change from blue to cyan due to the different afterglow decay lifetimes of the Dy3+ emission peaks. Based on the above luminous mode Ca3Al2Ge3O12:Re3+ (Re3+=Tb3+, Pr3+, Dy3+), developed multiple anti-counterfeiting devices that can be used for passport and fingerprint verification, etc. In addition, under the high-temperature conditions, there will still be an afterglow color display, and the multi-level anti -counterfeiting strategies can be used to solve counterfeiting problems in various fields.