Near-Infrared Luminescence Enhancement by Co-Doped Bi<sup>3+</sup> in YVO<sub>4</sub>:Yb<sup>3+</sup>

The near-infrared (NIR) luminescence phosphor Yb ,Bi + co-doped YVO4 was prepared by a conventional solid state method and the sensitization of Yb + near-infrared luminescence by Bi + was investigated. By co-doping with Bi from 0 to 0.05 the characteristic NIR luminescence of Yb in the YVO4 matrix was greatly enhanced and the strongest site of the excitation wavelength red-shifted from 335 to 352 nm while the wavelength range of the excitation spectrum broadened from 300-360 to 300-430 nm. The optimized Bi + content is 0.03. The possible energy transfer mechanism among VO4 , Bi + , and Yb + was discussed. We conclude that the NIR luminescence of YVO4:Yb + can be remarkably improved by co-doping with Bi and its absorbance matches better with the solar energy spectrum. YVO4:Yb, Bi is a promising spectral converter for silicon solar cells and it is expected to improve the photoelectric conversion efficiency.