Enhancing the broadband near-infrared photoluminescence and persistent luminescence of Cr3+ in Mg1.4Zn0.6SnO4 by Bi3+ codoping

In this study, a series of non-gallate broadband near-infrared Mg 1.4 Zn 0.6 SnO 4 :Cr 3+ ,Bi 3+ phosphors were successfully synthesized via solid-state reaction method. Occupying octahedral sites in a weak crystal field environment, Cr 3+ ions in Mg 1 . 4 Zn 0 . 6 SnO 4 exhibit intense broadband near-infrared emission centered at 759 nm, which originates from two distinct Cr 3+ centers located at Sn 4+ and Mg 2+ /Zn 2+ sites. Although Bi 3+ does not contribute to luminescence in this phosphor and its co-doping has minimal influence on the crystal structure, Cr 3+ valence, or the concentration of effective traps, it significantly enhances both the luminescence efficiency and persistent luminescence performance by improving the crystallinity of the phosphor. With Bi 3+ codoping the external quantum efficiency of the phosphor was promoted from 15 % to 21 % and the persistent-luminescence duration was extended to over 48 h. Furthermore, the potential application of Mg 1.4 Zn 0.6 SnO 4 :0.01Cr 3+ ,0.07Bi 3+ in NIR phosphor-converted LED is explored and demonstrated. This work not only provide a new non-gallate broadband near-infrared phosphor but also proposes a new strategy for synchronously improving the luminescence efficiency and persistent-luminescence performance of Cr 3+ activated phosphors for multifunctional applications.