Ultra‐Broadband Near‐Infrared Emission in Cr 3+ ‐Doped CaMg 2 Lu 2 Ge 3 O 12 Garnet Phosphor via Cation Substitution and Energy Transfer

ABSTRACT Broadband near‐infrared phosphor‐converted light‐emitting diode (NIR pc‐LED) can be used in various fields, such as spectroscopy, non‐destructive testing, and night vision lighting. How to obtain novel phosphors owned ultra‐broadband is also a significant challenge. Here, a novel broadband CaMg 2 Lu 2 Ge 3 O 12 :Cr 3+ garnet phosphor is synthesized. CaMg 2 Lu 1.95 Ge 3 O 12 :5%Cr 3+ exhibits broadband emission in the 600–1100 nm with a full width at half maximum (FWHM) of 120 nm and excellent thermal stability, which can maintain 83%@423 K. The NIR pc‐LED achieves a high photoelectric conversion efficiency of 18.47%@10 mA and an output power of 43 mW@100 mA. The spectral range is further extended by a synergistic strategy combining Sc substitution and co‐doped Ni 2+ ions. CaMg 2 Sc 1.95 Ge 3 O 12 :5%Cr 3+ achieves an ultra‐broadband emission in 600–1400 nm, with the emission peak redshifted from 750 to 850 nm, and the FWHM was broadened from 120 to 280 nm. CaMg 2 Lu 1.92 Ge 3 O 12 :5%Cr 3+ , 3%Ni 2+ exhibits broadband emission at 1460 nm of Ni 2+ ions in 1200–1900 nm with a FWHM of 316 nm under 450 nm excitation. Furthermore, the water, ethanol, and ethylene glycol liquids can be effectively distinguished as well as blood vessels, peas inside pods, fingernails within capsules, and embedded chips in campus cards can be clearly observed under the NIR pc‐LED device.