A novel rear reflector structure that combines NIR light harvesting β-NaGdF4:Yb, Er, Fe upconversion nanoparticles (UCNPs) and light reflecting silver particles has been successfully used to improve the performance of dye-sensitized solar cells (DSSCs). The power conversion efficiency of DSSCs with a rear reflector was 7.04%, which is an increase of 21.3% compared to the cell without a rear reflector (5.8%).