The hydrothermally synthesis of K3AlF6:Cr3+ NIR phosphor and its performance optimization based on phase control

Phosphor-convert (pc) near-infrared (NIR) LED is the next-generation smart NIR light sources. Thus, NIR phosphors are quickly developed. The K 3 Al 1−x F 6 :xCr 3+ (KAF:Cr 3+ ) NIR phosphor shows broadband emission from 650 to 900 nm under 430 nm and can be used to fabricate NIR LEDs. In this work, KAF:Cr 3+ phosphors were prepared by a hydrothermal method for the first time. Morphologies and NIR properties are tuned by controlling the hydrothermal processes. Different from the cubic KAF:Cr 3+ synthesized by a coprecipitation method, KAF:Cr 3+ synthesized by the hydrothermal method shows the tetragonal phase. The optimized KAF:3%Cr 3+ shows an internal quantum efficiency of about 31.4%. A NIR pc-LED device was fabricated by integrating the KAF:3%Cr 3+ phosphor with a blue LED chip (~450 nm). The output power of NIR light is about 5.5 mW driven at 150 mA.