Highly efficient near-infrared phosphor LaMgGa11O19:Cr3+

Abstract

Near-infrared (NIR) phosphor-converted light-emitting diodes (pc-LEDs) are desirable for in vivo imaging and applications for nondestructive examination in the food industry. Accordingly, it is very important to exploit highly efficient and stable broad-band NIR phosphors. Herein we report a Cr³⁺-activated LaMgGa₁₁O₁₉ phosphor via a simple solid-state reaction, showing broad-band emission centered at 770 nm with internal/external quantum efficiency of 82.6%/42.5%. There are three six-coordinated octahedral crystallographic sites in the structure for Cr³⁺ occupancy, and changing the Cr³⁺ concentration can tune the NIR emission with tunable band centers from 715 to 800 nm. This spectral red-shift is mainly ascribed to energy transfer among multiple Cr³⁺ sites, which is further confirmed by decay lifetime analysis. The phosphor also shows excellent luminescence thermal stability, and the photoluminescence intensity at 410 K maintains 87% of that at room temperature. Our work provides a novel broadband NIR emission phosphor with high efficiency and excellent thermal quenching resistance for the field of NIR spectroscopy.