Dynamic color-tunable persistent zinc-cadmium silicate composites phosphor: Design, preparation and application

Persistent luminescence (PersL) has drawn intense attention because of its widely practical applications. Dynamic color-tunable PersL is desired and fascinating for advanced anti-counterfeiting, information storage, etc. However, it is difficult to obtain and rarely reported. Herein, a simple and effective method by using coordination polymers (CPs) as precursors is designed for color-tunable zinc-cadmium silicate composites PersL phosphors. Compared with pure Zn2SiO4 (ZSO) and CdSiO3 (CSO), the composites (ZSO/CSO) exhibit significantly improved brightness and dynamic tunable color. With time evolution, the color varied from white to yellow to orange and finally even to red. Notably, the duration time of 1.0 % Dy3+ doped ZSO/CSO is prolonged to 19000 s (>5 h) at the threshold value (0.32 mcd/m2) after 254 nm irradiation, showing a more than 100-fold enhancement compared with CSO. In attempt to achieve a better understanding of the enhanced mechanisms, the formation energy of Dy3+ and O-vacancy are accurately derived from first-principles calculations. Combined with thermoluminescence (TL) measurement, the PersL mechanism is proposed. Finally, the application of ZSO/CSO:1.0 % Dy3+ in displaying and anti-counterfeiting was explored. This work not only provides a new way to the design of PersL phosphors through composite compounds, but also promotes the development of PersL phosphors in practical applications.