Achieving opto-responsive multimode luminescence in Zn1+xGa2−2xGexO4:Mn persistent phosphors for advanced anti-counterfeiting and information encryption

Optical characteristics of phosphors, e.g. color output, decay process and external field stimulation mode (including opto-, thermo- and mechano-stimulation), play an important role in the areas of information storage, anti-counterfeiting and bio-imaging applications. Persistent luminescence (PersL) phosphors are particularly suitable for such applications owing to their multimodal luminescence features such as photoluminescence (PL), PersL, photostimulated luminescence and mechanoluminescence. However, conventional PersL phosphors are suffering from a huge challenge to develop a single material for multicolor anti-counterfeiting. Herein, the Zn 1+ x Ga 2−2 x Ge x O 4 :Mn (0 ≤  x  ≤ 1) solid solution phosphors are synthesized, which can emit from green to yellow, golden, pink, and red PL. In addition, the phosphors also show the thermo-mechano-opto-stimulated green PersL after irradiation of a UV 254/365 nm lamp. Based on the multimode and multicolor luminescence features, the advanced anti-counterfeiting and optical data storage are designed. Results show that the multimodal luminescence feature with high information capacity can be conveniently identified by using a luggable ultraviolet lamp or NIR laser diode. This extraordinary material will make anti-counterfeiting more sophisticated and show advanced security in the applications of data encryption.