Discovery of the Yb2+–Yb3+ couple as red-to-NIR persistent luminescence emitters in Yb-activated (Ba1−xSrx)AlSi5O2N7 phosphors

Abstract

In this work we reported novel Yb-doped (Ba_1−xSr_x)AlSi₅O₂N₇ phosphors showing intense persistent luminescence (PersL) in the visible and near-infrared (NIR) regions simultaneously. Both Yb²⁺ and Yb³⁺ were found to be PersL emitters, which presented a broad emission band centered at 664 nm and a sharp emission at 980 nm, respectively. The radiance of PersL in the Ba_0.8Sr_0.2AlSi₅O₂N₇:Yb phosphor at 60 min after ceasing UV irradiation was 4.82 × 10⁻³ mW Sr⁻¹ m⁻², approximately one-third of the well-known ZnGa₂O₄:Cr³⁺ PersL phosphor. The results demonstrate that Yb could be a promising red-to-NIR PersL emitter and more Yb-activated phosphors could be developed for red-to-NIR PersL.