Efficient White‐Light‐Excited Garnet NIR Phosphors With Robust Thermal Stability

ABSTRACT Near‐infrared (NIR) luminescent materials have shown promising for anti‐counterfeiting and bioimaging. However, most of the current NIR luminescent materials rely solely on ultraviolet (UV) or blue light excitation, raising concerns about phototoxicity and tissue damage in biological contexts. Herein, we present a newly designed garnet‐based NIR phosphor Y 2 BaGa 4‐ x SiO 12 : x Cr 3+ (YBGSO:Cr 3+ ), that can be excited by broadband white light. Its emission bandwidth is highly adjustable, spanning 74–210 nm tunable. The optimized composition, YBG 3.92 SO:0.08Cr 3+ , presents triple stability: near‐unity internal quantum efficiency, anti‐thermal quenching (retaining 111% ± 2.9% of its emission intensity at 423 K), and remarkable chemical stability (93% emission preserved after 35‐day immersion). These attributes enable white light—not just UV or blue light—to serve as a practical, biocompatible, and high‐efficiency excitation source. The underlying mechanism stems from absorption contributions across the entire visible spectrum present in white light. A prototype NIR phosphor‐converted light‐emitting diode (pc‐LED) fabricated with this material delivers an output power of up to 298 mW at 100 mA, outperforming the commercial devices Osram SFH4650. The device retains 91% of initial output power after 100 h of continuous operation. This work provided a brand‐new excitation mode for NIR phosphors, advancing their practical use in white‐light‐excited information encryption, anti‐counterfeiting, and bioimaging.