CdSe quantum dots (QDs) were adsorbed onto nanostructured ${\text{TiO}}_2$ films for different times by using a chemical bath deposition method in order to produce QD-sensitized solar cells (QDSSCs). Surface modification was done by coating ZnS onto the CdSe QDs. The optical absorption and current-voltage characteristics of these devices were studied. The size of the CdSe QDs increased with increasing adsorption time, and there was an optimum CdSe adsorption time for achieving the best photovoltaic conversion efficiency. The photovoltaic properties of short-circuit current density, open-circuit voltage, and photovoltaic conversion efficiency were significantly improved after modifying the surface with ZnS. Under a solar illumination of $100\text{mW}/{\text{cm}}^2$ , an efficiency as high as 2.02% was achieved for the CdSe QDSSCs that were made by using this method.