Enhanced and Broadened NIR Emission of CaZnGe2O6:Cr3+ by Yb3+ Codoping for NIR Applications

Compact and portable near-infrared (NIR) light sources have been widely used in the fields of NIR spectroscopy, night vision lighting, medical measurement, etc. Although Cr 3+ -activated phosphors have been widely reported, achieving broadband and high-efficiency near-infrared emission remains of great significance. In this work, CaZnGe 2 O 6:Cr 3+ with highly efficient and ultrabroadband NIR emission was synthesized by a solid reaction method, and Yb 3+ -codoping not only enhanced the NIR emission efficiency but also broadened its emission band. As the absorption efficiency was greatly improved due to Yb 3+ doping, CaZnGe 2 O 6:Cr 3+,Yb 3+ presented excellent NIR emission properties with a fwhm of 295 nm, an internal quantum efficiency (IQE) of 98.4, an external quantum efficiency (EQE) of 31.1%, and an effective emission band for NIR spectroscopy over 350 nm. A pc-LED was prepared by packaging the CaZnGe 2 O6:Cr 3+,Yb 3+ phosphor with a 460 nm LED chip, and its NIR electro-optical conversion efficiency and output power reached 12.9%@100 mA and 249.3 mW@300 mA, respectively. This pc-LED can illuminate a pattern clearly on wall 15 m away and demonstrated application in NIR spectroscopy through the measurement of the glucose solution concentration. Our results indicate that the CaZnGe 2 O 6:Cr 3+,Yb 3+ ultrabroadband NIR phosphor is a high-performance light source material for portable compact NIR devices.