We report on spectral modification from visible to near-infrared (NIR) in Pr 3+ and Yb 3+ codoped oxyfluoride glass for c-Si solar cell. The excitation and emission spectra indicate the energy transfer from Pr 3+ to Yb 3+ . The theoretical quantum efficiency is calculated based on the fluorescent lifetime and has reached more than 150%. However, the external quantum efficiency (EQE) of the Pr 3+ and Yb 3+ codoped glass covered on silicon solar cell is decreased compared to that of the host glass. The reasons of the negative effect of spectral modification on EQE are discussed and analyzed.