The co-optimization of efficiency and emission bandwidth in GSAGG:Cr3+NIR ceramic phosphors

The NIR phosphor-converted light-emitting diode (NIR pc-LED) is a new near-infrared light source that has been widely studied. Among various NIR phosphors, Cr3+ doped gadolinium aluminum gallium garnet (GAGG:Cr3+) ceramic phosphor has shown great potential due to its ultra-high efficiency and thermal stability. Despite its capabilities, its detection range may be limited due to a relatively narrow emission bandwidth. To make the GAGG:Cr3+ ceramic phosphors achieve both high efficiency and broadband emission, a series of Gd3Al2-x-yScxGa3O12:yCr3+ (GASGG:Cr3+) ceramic phosphors were prepared. Thanks to the decrease of crystal field strength with the doping of Sc3+, the full width at half maximum (FWHM) of GASGG:Cr3+ ceramic phosphors were extended from 84 nm to 117 nm, and the emission peak exhibited a red-shift of 46 nm. Meanwhile, it still retained extremely high external quantum efficiency (EQE = 47%) and excellent thermal stability (90.7% @150 degrees C). Then, a NIR pc-LED prototype device was fabricated by combining GASGG:Cr3+ ceramic phosphor with a blue LED chip. The NIR light output power and the photoelectric conversion efficiency of this device achieved 646 mW and 19.2%, respectively. Finally, the application effect in night vision and venography of this prototype device was demonstrated.