Controllable persistent luminescence in bismuth activated memory phosphors by trap management for artificial intelligence anti-counterfeiting

Abstract

The management of multicolour and multimode luminescence in persistent luminescence (PersL) materials plays a crucial role in encrypting information to combat forgery. Although luminescent anti-counterfeiting has made significant progresses, anti-counterfeiting signals only exhibit typical luminescent emission colours of materials under fixed external stimuli, which makes them susceptible to be replicated. Here, we developed a series of LiReGeO₄:Bi,Ln (Re = Lu, Y and Gd, Ln = Eu, Tb, Pr, Yb, Sm, Tm, Ce, Dy and Er) phosphors with multicolour and on-demand controlled PersL emission through purposeful design of the electron–hole pair trap structure. Besides the multicolour and multimode emission, these phosphors demonstrated a temporal memory function for writing information, which provides a new dimension for higher-order anti-counterfeiting. As an example, LiLuGeO₄:Bi,Ln (Ln = Eu, Tb, Pr and Yb) memory phosphors display the pattern signals in the order requested by the owner, which makes any sophisticated forgery technique powerless. The study here provides not only a simplistic method for constructing a new-type persistent memory material, but also a new paradigm of artificial intelligence memory for anti-counterfeiting technology.