Efficient Super Broadband NIR Ca₂LuZr₂Al₃O₁₂: Cr³⁺, Yb³⁺ Garnet Phosphor for pc-LED Light Source toward NIR Spectroscopy Applications

Super broadband near-infrared (NIR) phosphor converted light-emitting diodes (pc-LEDs) are future light sources in NIR spectroscopy applications such as food testing. At present, a few blue LED excitable super broadband NIR phosphors (bandwidth > 300 nm) have been developed producing the NIR output powers below 26 mW at 100 mA input current after LED packaging. Here, an efficient super broadband NIR phosphor achieved by doping Yb³⁺ is reported in the NIR Ca₂LuZr₂Al₃O₁₂:Cr³⁺ (CLZA:Cr³⁺) garnet phosphor developed previously. Benefited from the superposition of Cr³⁺ emission and highly efficient Yb³⁺ emission excited by energy transfer from Cr³⁺, the codoped CLZA:Cr³⁺,Yb³⁺ phosphor shows a bandwidth of 320 nm and an internal quantum efficiency of 77.2% both higher than that (150 nm and 69.1 of singly doped CLZA:Cr³⁺ phosphor. The codoped phosphor converts LED produced 41.8 mW NIR output at 100 mA input current. The pc-LED as a light source is also well applied to the NIR transmission spectra measurement of water. The results indicate the great potential of CLZA:Cr³⁺,Yb³⁺ phosphor in super broadband NIR pc-LED applications.