Long persistent composite phosphor CaAl2O4:Eu2+,Nd3+/Y3Al5O12:Ce3+: a novel strategy to tune the colors of persistent luminescence

Enhancing the afterglow intensity and prolonging the persistence time, stimulates the applications of long persistent phosphors. However, current methods to improve the luminescent properties of persistent phosphors are invariably complicated. In this work, we demonstrate a simple but effective strategy to manipulate and expand the color of persistent luminescence, through the radiative energy transfer from CaAl2O4:Eu2+,Nd3+ (CA) to Y3Al5O12:Ce3+ (YAG). It is significant to observe that in the CA/YAG composites, the afterglow intensity can be enhanced ∼2.7-fold and the persistence time can be prolonged ∼2.8-fold in comparison with the widely used CA. A white light persistent luminescent composite (B : Y = 10 : 5) with a decay time of 45 h is obtained. Investigations into the mechanism indicate that the great enhancement of the intensity and persistence time of the long persistent luminescence is directly driven by photopic luminous efficiency and the photo-releasing of energy stored in deep traps. Moreover, the persistent luminescence color of the composites can be tuned from blue to yellow through adjusting the YAG content. In addition, the potential and universality of this color manipulation approach are validated. These results will be greatly beneficial for the applications of long persistent phosphors.