Cr3+-Doped Sc-Based Fluoride Enabling Highly Efficient Near Infrared Luminescence: A Case Study Of K2nascf6:Cr3+

The development of highly efficient and thermally stable broadband near-infrared (NIR) luminescence materials is a great challenge to advance the next-generation smart NIR light source. Benefitting from the low phonon energy and relatively weak electron phonon coupling effect of the fluoride, K2NaScF6:Cr3+ phosphor is designed and obtained, which demonstrates a full width at half maximum of 100 nm peaking at approximate to 765 nm. Upon blue light excitation, the phosphor exhibits a high quantum efficiency of 74% and its emission intensity at 150 degrees C can keep 89.6% of the initial value at 25 degrees C. An NIR output power of 159.72 mW (input electric power, 1094 mW) with a high photoelectric conversion efficiency of approximate to 14.60%, light-emitting diode (LED) device is presented based on this K2NaScF6:Cr3+ phosphor. Furthermore, applying the high-power NIR phosphor-converted LED device as lighting source, clear and quick veins imaging and recognition in fingers, palm, wrist, and arm of the human hand are first realized, suggesting K2NaScF6:Cr3+ phosphor has high promise in practical applications.