Cr3+-Doped La2MgSnO6 Double Perovskite Phosphors for Near-Infrared pc-LEDs

Cr3+-doped near-infrared (NIR) phosphors exhibit peculiar advantages in fabricating NIR phosphor-converted light-emitting diodes (NIR pc-LEDs) for machine/night vision, plant cultivation, and nondestruction detection. However, efficient NIR phosphors doped with Cr3+ usually contain noble/rare metal ions such as In, Sc, Ga, and Ge, thus making it an essential mission to develop much cheaper NIR phosphors. In this work, we report an inexpensive broadband NIR phosphor, La2MgSnO6:Cr3+ (LMS:Cr3+), that can be easily synthesized in air. LMS:Cr3+ has two distorted octahedra lattice sites for Cr3+ doping and displays a wide emission spectrum covering the range of 600-1200 nm with an emission maximum of 751 nm and a full width at half-maximum (fwhm) of 104 nm under 450 nm excitation. The broadband NIR emission originated from two distinct crystallographic sites and a medium-strength crystal field for Cr3+. LMS:Cr3+ shows an optical band gap of 3.72 eV, and its emission intensity can still maintain 68.5% at 423 K. Finally, a prototype NIR pc-LED fabricated by combining LMS:0.01Cr(3+) and a blue LED is demonstrated for applications in plant cultivation, night vision, and recognition of cultural relics.