To improve energy conversion efficiency (E-ff) of silicon solar cells, luminescent down-conversion (DC) is an effective approach to adjust solar spectrum by converting ultraviolet light to visible and near-infrared light. In this paper, Tb3+-Yb3+ co-doped NaYF4 phosphors (DCNPs) were successfully synthesized by a simple solvothermal method. It was confirmed from the strong photoluminescence excitation (PLE) and photoluminescence (PL) emission peaks that the energy transfer occured between Tb3+ and Yb3+ ions. The DCNPs were added in the SiO2 sol-gel to prepare anti-reflection coatings with DC performance, enhancing the visible and near-infrared region transmittance which matched with the band gap of silicon. An optimized short-circuit current density (J(sc)) of 33.39 mA/cm(2) and a relatively enhanced E-ff of 6.74% were achieved in the silicon solar cells with the bi-functional film. These results indicated the availability of anti-reflection coating with DCNPs for improving energy conversion efficiency of silicon solar cells.