•GNF added PEO/(PVDF-HFP) polymer electrolyte successfully prepared.•0.005g GNF added polymer electrolyte shows the best electrochemical performances.•GNF leads to generated charge carriers quickly insert to TiO2 film.•The ionic conductivity of 0.005g GNF is 8.67×10−4scm−1.•Cell efficiency increased to 4.60% with 0.005g GNF added polymer electrolyte. The PEO and PVDF-HFP mixtures were used as polymer electrolytes in solid-state dye-sensitized solar cells (DSSCs). Correlation between the ionic conductivity and cell performance by varying the composition of polymer electrolytes was investigated to elucidate the importance of the ionic conductivity in determining the charge transfer and energy conversion efficiency of solid-state DSSCs. In this work, for increasing the ionic conductivity and charge transfer, GNF was added to the polymer electrolyte. The ionic conductivity of polymer electrolyte containing GNF (0.005g) is 8.67×10−4Scm−1 and pristine polymer electrolyte is 3.81×10−4Scm−1. The charge transfer of GNF (0.005g) added DSSCs is faster than the other samples, the electron transport time is 1.53ms and electron life time is 27.20ms. The increase of current density with the polymer electrolyte containing GNF (0.005g) can be possibly attributed to the direct contact between dye/TiO2 and I−/I3− that will improve the charge transportation. The highest energy conversion efficiency of 4.60% is obtained for polymer electrolyte containing GNF (0.005g).