A novel AlF3:Cr3+ NIR phosphor with high thermal quenching stability for advanced pc-LEDs

Near-infrared phosphor-converted light-emitting diodes (pc-LEDs), as the core light source for smart broadband near-infrared spectroscopy, face critical challenges in balancing luminous efficiency and thermal stability. Herein, we report a Cr3+-doped fluoride phosphor AlF3:Cr3+ with efficient broadband near-infrared (NIR) emission. Under blue-light excitation, AlF3:Cr3+ exhibits a broadband NIR emission centered at 749 nm with a full width at half maximum (FWHM) of 87 nm. Notably, it shows excellent thermal stability, retaining 86.28% of its room-temperature luminescence intensity at 423 K (150 °C). This superior anti-thermal quenching property is attributed to the weak electron–phonon coupling in its crystal structure, characterized by a low Huang–Rhys factor (S = 2.15). By integrating this phosphor with a blue LED chip, we fabricated a NIR pc-LED device with a photoelectric conversion efficiency of 2.2%@20 mA. The device would demonstrate significant advantages in diverse fields, including nondestructive testing, biomedical imaging, and intelligent security, highlighting the great potential of AlF3:Cr3+ for industrial applications.