Cr3+-doped double-perovskite Sr2(Sc/In)NbO6 phosphors with broadband near-infrared emission

Abstract

Cr³⁺-activated broadband near-infrared (NIR) phosphors have attracted considerable interest due to their potential for next-generation intelligent NIR light sources. In this work, novel broadband near-infrared (NIR) phosphors of Cr³⁺-doped Sr₂(Sc/In)NbO₆ were successfully prepared by a solid-state reaction method. Cr³⁺-doped Sr₂ScNbO₆ and Sr₂InNbO₆ exhibit broadband emissions ranging from 700 to 1200 nm centered at 830 nm and 850 nm, respectively, due to the ⁴T₂–⁴A₂ transitions. The optimal doping concentrations of Cr³⁺ in the Sr₂ScNbO₆ and Sr₂InNbO₆ were experimentally determined to be 0.3 % and 0.5 % with PLQY of 40.1 % and 35.2 %, respectively. The activation energy, a measure of thermal quenching performance, for Sr₂ScNbO₆:Cr³⁺ and Sr₂InNbO₆:Cr³⁺ were calculated to be 0.131 and 0.110 eV, respectively. The mechanisms behind the NIR luminescence and thermal quenching were illustrated in detail. Encapsulating prototype broadband NIR phosphor-converted light-emitting diode (pc-LED) devices by combining the as-obtained phosphors with blue LED chips yields the highest NIR output power of 13 mW at 300 mA and a photoconversion efficiency (PCE) of 10 % at 30 mA, enabling bio-imaging applications.