High Output Power and High Quantum Efficiency in Novel NIR Phosphor MgAlGa0.7B0.3O4:Cr3+ with Profound FWHM Variation

Abstract There is strong demand for ultraefficient near‐infrared (NIR) phosphors with adjustable emission properties for next‐generation intelligent NIR light sources. Designing phosphors with large full‐width at half‐maximum (FWHM) variations is challenging. In this study, novel near‐ultraviolet light‐emitting diode (LED)‐excited NIR phosphors, MgAlGa 0.7 B 0.3 O 4 :Cr 3+ (MAGBO:Cr 3+ ), with three emission centers achieve ultra‐narrowband (FWHM = 29 nm) to ultra‐broadband (FWHM = 260 nm) emission with increasing Cr 3+ concentration. Gaussian fitting and decay time analysis reveal the alteration in the FWHM, which is attributed to the energy transfer occurring between the three emission centers. The distinct thermal quenching behaviors of the three emission centers are revealed through the temperature‐dependent decay times. The ultra‐broadband NIR phosphor MAGBO:0.05Cr 3+ exhibits high thermal stability (85%, 425 K) and exceptional external quantum efficiency of 68.5%. An NIR phosphor‐converted LED (pc‐LED) is fabricated using MAGBO:0.05Cr 3+ phosphor, exhibiting a remarkable NIR output power of 136 mW at 600 mA in ultra‐broadband NIR pc‐LEDs. This study describes the preparation of highly efficient phosphors and provides a further understanding of the tunable FWHM, which is vital for high‐performance NIR phosphors with versatile applications.