A new persistent blue-emitting phosphor: Tailoring the trap density for enhancing the persistent time

In recent times, non-Eu2+ based persistent phosphor materials show promise for self-sustained night vision surveillance and bio-imaging owing to their ability to luminesce overnight, high chemical stability, and broad-band absorption. While green and yellow wavelengths are widely explored, the research and development of persistent phosphors in the blue region are still lacking, owing to the limited understanding of the luminescence persistence mechanism. Herein, it is to be reported a new blue-emitting Na3ScSi3O9:Ce3+, Dy3+ phosphor, which exhibits a strong emission at 450 nm that persists for nearly 17 h above the recognizable intensity level (0.32 mcd/m2), which is the longest persistent phosphor in the blue region. Thermoluminescence experiments reveal a fifth-order-of-magnitude rise in the trap density by Dy3+ incorporation into Na3ScSi3O9:Ce3+, which is responsible for the long persistence of the emission. Furthermore, by employing Mn2+, Tb3+, and Dy3+ as co-activators, it is realized that the trap density is proportional to the persistence time. Finally, an underlying mechanism for this blue emission persistence is proposed. These results might push forward the design of new blue-emitting phosphors with higher persistent luminescence efficiencies.