Highly Efficient and Thermally Stable Broadband NIR Phosphors with Superlong Afterglow Performance and their Multifunctional Applications

Abstract Near‐infrared (NIR) phosphor‐converted light‐emitting diodes (pc‐LEDs) are considered as promising next‐generation light sources for optoelectronic and biomedical applications. Nevertheless, NIR phosphors with large bandwidths, long emission peaks, high external quantum efficiencies (EQEs) and valuable thermal stabilities are challenging to develop. Herein, this study reports a novel gallium germanate host, Ga 3 Al 3 Ge 2 O 13 (GAGO), with a large bandgap and rigid host lattice for Cr 3+ ion doping. The blue LED excitable GAGO:0.012Cr 3+ phosphor can produce broadband NIR emission with a maximum intensity at 816 nm and a full‐width at half‐maximum (FWHM) of 187 nm. Notably, the phosphor also exhibits an excellent EQE of 35.8% and perfect thermal stability (I 423 K /I 298 K = 67.4%). Moreover, an attractive NIR afterglow duration of more than 24 h is achieved in the GAGO:0.004Cr 3+ phosphor. The type and origin of the traps are discussed, and a possible long persistent luminescent (LPL) mechanism is proposed. Finally, an NIR pc‐LED based on a GAGO:0.012Cr 3+ phosphor is fabricated. The results demonstrate that the obtained phosphors show great potential for use in night vision, nondestructive detection, bioimaging and information encryption. This study provides new insight into the development of broadband NIR luminescent materials with high efficiency, good thermal stability and extraordinary afterglow performance.