Nonstoichiometry-Induced Self-Activated Phosphors for Dynamic Anti-counterfeiting Applications
Yue Yang, Ting Wang, Yajing Yan, Longchao Guo, Xuanyu Zhu, Weifang Bu, Guohao Wang, Nannan Zhu, Lei Zhao, Xue Yu
Abstract
Optical signals with distinctive properties, such as contactless, fast response, and high identification, are harnessed to realize advanced anti-counterfeiting. However, the simultaneous attainment of multi-color, -temporal, and -modal luminescence performance remains a compelling and imperative pursuit. In our work, a temperature/photon-responded dynamic self-activated luminescence originating from nonstoichiometric Zn 2 GeO 4 is developed with the modulation of intrinsic defects. The increased concentration of oxygen vacancies (V O •• ) contributes to an enhanced recombination of Zn Ge ″ –V O ••, ultimately improving the self-activated luminescence performance. Additionally, the photoluminescence (PL) color of the representative Zn 2.2 GeO 4 sample changes from green to blue–white with the increased ultraviolet (UV) irradiation time. Concurrently, the emission color undergoes a variation from blue to green as the ambient temperature raises from 280 to 420 K. Remarkably, green long persistent luminescence (LPL) and photostimulated luminescence (PSL) behaviors are observed. Herein, this study elucidates a sophisticated anti-counterfeiting approach grounded in the dynamic luminescent attributes of nonstoichiometric Zn 2 GeO 4, presenting a promising frontier for the evolution of anti-counterfeiting technologies.