Near-infrared A2KAlF6:Cr3+ (A = Rb, Cs) phosphors with high thermal stability for full-spectrum illumination

Herein, NIR A2KAlF6:Cr3+ (A = Rb, Cs) phosphors prepared by a co-precipitation method exhibit broad excitation in the blue region and broad NIR emission with high quantum efficiencies (64% for Rb2KAlF6:0.025Cr3+, and 60% for Cs2KAlF6:0.02Cr3+). Furthermore, Rb2KAlF6:Cr3+ and Cs2KAlF6:Cr3+ phosphors maintain 95.3% and 90.2% of their room-temperature initial intensity at 150 °C, respectively. The full-spectrum white light-emitting diode (WLED) based on Rb2KAlF6:Cr3+ exhibits a high color-rendering index (94.8), a high luminous efficiency (99.5 lm/W), and a low correlation color temperature (3666 K). The results reveal that these phosphors can not only apply in full-spectrum illumination but also provide new in-depth insights into the design of NIR phosphors with high efficiency and thermal stability.