A novel high-efficient NIR emitting phosphor Ca2YAl3Ge2O12:Cr3+ enabled by chemical unit co-substitution

Near-infrared phosphor-converted light-emitting diodes (NIR pc-LEDs) demonstrate a great prospect for applications in the field of bioimaging, modern agriculture, and nondestructive examination. Developing NIR emitting phosphor with high quantum efficiency (QE) and thermal stability is a significant issue. Herein, a novel highly efficient NIR-emitting phosphor Ca2YAl2.95Ge2O12:0.05Cr(3+) is reported. Through chemical unit co-substitution of [Ca2+ + Ge4+] by [Al3+ + Y3+] in Ca3Al1.95Ge3O12:0.05Cr(3+), when one-third of the Ca2+/Ge4+ sites were replaced by Y3+/Al3+, the internal and external QEs are 84.1 % and 38.6 %, respectively. Its emission peak was red-shifted to 780 nm compared with that of Ca3Al1.95Ge3O12:0.05Cr(3+), which is in favor of matching with the absorption band of phytochrome P-FR (600-800 nm). The Ca2YAl2.95Ge2O12:0.05Cr(3+) phosphor shows high heat stability and its photoluminescence (PL) intensity at 423 K remains 80.38 % of that at 300 K. The photoelectronic conversion efficiency of the NIR pc-LED device fabricated by Ca2YAl2.95Ge2O12:0.05Cr(3+) phosphor and 450 nm blue chip can reach 15.88 % at 180.5 mA drive current. All the results indicate that Ca2YAl2.95Ge2O12:0.05Cr(3+) phosphor has excellent application potential in night vision and plant lighting