Achieving\na Balance of Good Quantum Efficiency and\nThermal Stability in the Y<sub>2</sub>CaScAl<sub>3</sub>GeO<sub>12</sub>:Cr<sup>3+</sup> Broadband Phosphor for Multiple NIR Spectroscopy\nApplicatio

Near-infrared phosphor-converted\nlight emitting diodes\n(NIR pc-LEDs)\nare considered as desirable NIR light sources to satisfy current needs\nowing to their numerous remarkable features. Nevertheless, as an essential\ncomponent, previously reported NIR phosphors with broadband emission\noften suffer from inferior efficiency or thermal stability, therefore\nrestricting their use and promotion. Herein, a novel Cr<sup>3+</sup>-doped garnet phosphor Y<sub>2</sub>CaScAl<sub>3</sub>GeO<sub>12</sub>:Cr<sup>3+</sup> (YCSAG:Cr<sup>3+</sup>) is developed via regulating\nthe near-neighbor coordination polyhedron. Under the excitation of\nblue light, it exhibits a broadband NIR emission peaking near 800\nnm with a full width at half-maximum (fwhm) exceeding 150 nm, owing\nto the increased structural distortion of the octahedron. Particularly,\ndue to the enhanced local structural rigidity induced by lattice shrinkage,\nthe optimal sample achieves a balance of high internal quantum efficiency\n(IQE) of approximately 83% and thermal stability of approximately\n90% at 393 K, facilitating its practical application as an NIR light\nsource. Eventually, using the typical YCSAG:0.04Cr<sup>3+</sup> phosphor\nand 450 nm blue LED chip, a high-performance NIR pc-LED device has\nbeen manufactured, demonstrating potential applications in anticounterfeiting\nand night vision.