Broadband Near-Infrared Emitting Phosphor CaLaMgTaO6:Cr3+ toward Multiscenario Light-Emitting Diode Applications

The crystal phase, morphology, photoluminescence properties, and practical application potentials of a new phosphor, CaLaMgTaO6:Cr3+, were investigated. The optimized phosphor exhibits intense, broad emission peaking at 815 nm upon 470 nm excitation, with an internal quantum efficiency as high as 63.1% and full width at half maximum of 171 nm. This emission originates from the 4T2→4A2 electronic transition of Cr3+ ions in a weak octahedral crystal field. The emission intensity remains 60% at 378 K. Such moderate thermal stability originates from the large Stokes shift, which is further corroborated by the low activation energy of 0.20 eV. Furthermore, a near-infrared lamp was packaged via coating CaLaMgTaO6:Cr3+ phosphor on a 450 nm LED chip. The prepared lamp is proven to support multiscenario applications, including clear, noninvasive vascular imaging in biological tissues and night vision imaging under dim light conditions.