We present a series of efficient near-infrared (NIR) Cr 3+ -doped non-gallate long-persistence phosphors (Zn 2 SnO 4 : Cr and Zn (2-x) Al 2x Sn (1-x) O 4 : Cr) and highlight their special optical characteristics of broad emission band (650-1200 nm, peaking at 800 nm) and long afterglow duration (435 h). In the context of materials selection, these systems successfully avoid the existing ubiquitous reliance on gallates as hosts in Cr 3+ -doped phosphorescent phosphors. Zn 2 SnO 4 is employed as a host to take advantage of its characteristic inverse spinel crystal structure, easy substitution into Zn 2+ and Sn 4+ sites by Cr 3+ in distorted octahedral coordination and non-equivalent substitution. In this work, Al dopant was introduced both to precisely tailor the local crystal field around the activator center, Cr 3+ , and to redeploy trap distribution in the system. Indeed, such redeployment permits band gap adjustment and the dynamic variation of the annihilation and the formation of defects. The results demonstrate that the method employed here can be an effective way to fabricate multi-wavelength, low-cost, NIR phosphorescent phosphors with many potential multifunctional bio-imaging applications.

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A novel phosphor with near-infrared (NIR) long persistent luminescence, SrSnO3:Bi2+ was successfully synthesized by traditional solid-state reaction.

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