Broadband Near-Infrared Garnet Phosphors with Near-Unity Internal Quantum Efficiency

Compact near-infrared (NIR) light sources with broad emission band are essential to enable NIR spectroscopy compatible with portable devices, and phosphor-converted light emitting diodes (pc-LEDs) are efficient, low-cost, and compact light sources. However, it is more challenging to develop highly efficient and thermally stable broadband NIR phosphors than conventional phosphors for white LEDs. Here, a series of solid solution phosphors with broadband NIR emission designed by cationic substitution in Cr3+ activated garnet Gd3Sc2Ga3O12 are reported. The internal quantum efficiency of Cr3+ emission can be significantly improved to nearly 100% via the substitution of ScO6 with smaller AlO6 octahedrons, which is attributed to the reduction of antisite defects. Moreover, the phosphor with optimized composition shows highly thermally stable emission, which renders the as-fabricated pc-LED with high-power (750.8 mW) NIR emission covering the wavelength range of 700-1000 nm. The results could advance the development of NIR pc-LEDs as high-performance light sources for miniature NIR spectrometers.