Dye-sensitized solar cells (DSSCs) are categorized as some of inexpensive thin-film solar cells. The basis and foundation of these cells is a semiconductor that consists of an electrolyte and a light-sensitive anode. Titanium dioxide (TiO2) is a semiconductor that plays the role of anode and is the main constituent of these cells. In this paper, we have addressed the functionality and performance of TiO2 films with thicknesses of 2.96, 7.54 and 11.1 micrometers in DSSCs. The morphology, crystal structure and the optical bandgap are some of the effective elements on the electron transfer rate and recombination process in the TiO2 film. When using TiO2, one must choose the optimum thickness to ensure optimal short-circuit current, open-circuit voltage and fill factor, so that the cell can have the highest possible efficiency. Analyzing the obtained characteristic curves, it is concluded that the efficiency of a cell with a 2.96 micrometer TiO2 film is 4.2%; the efficiency of a cell with a 7.54 micrometer TiO2 film is 5.54% and the efficiency of a cell with an 11.1 micrometer Tio2 film is 6%. Also, analyzing the EIS shows that the highest electron life time is 17 milliseconds which is obtained for the cell with an 11.1 micrometer TiO2 film. The films of TiO2 for each cell are provided by the doctor-blade deposition method and the dyes are deposited on their surface.