Near-infrared downconversion through host sensitized energy transfer in Yb3+-doped Na2YMg2(VO4)3

Host sensitized near-infrared emitting phosphor Na2YMg2(VO4)3:Yb3+ was fabricated by a sol-gel method. Efficient broad emission is observed under ultraviolet excitation ranging from 240 nm to −400 nm and this luminescence originates from ligand-metal charge transfer of 2p of O2− to 3d of V5+. Under excitation of ultraviolet light in the broad absorption band, intense near-infrared emission of Yb3+ around 974 nm is observed for Yb3+-doped Na2YMg2(VO4)3. Through study of photoluminescence spectra, fluorescence decay curves and concentration-dependent luminescence, mechanism of energy transfer from VO4 group to Yb3+ was proposed to rationalize the downconversion process. This phosphor with performance of ultra-violet to near-infrared downconversion could have potential application in improving efficiency of silicon-based solar cell.