Dye-sensitized solar cells (DSSCs) are promising photovoltaic device for converting sunlight into electrical energy, which have attracted significant attention due to their easy processing and low cost production. In this thesis, Carbon quantum dots (CQDs) optimized TiO2 photoanodes and their dye-sensitized solar cells (DSSCs) were successfully demonstrated. In the first stage CQD was synthesized from sucrose by a simple carbonizatiom method. The CQD-TiO2 composite films were prepared by electrophoretic deposition from stable suspension of TiO2 nanoparticles with different percentage of carbon quantum dots. FE-SEM images show a uniform layer without cracks for diffrrent electrodes. Electrochemical behavior of electrodes were studied using cyclic voltammetry and electrochemical impedance spectroscopy. According to results, charge transfer resistance of semiconductor film was decreased in the presence of CQD. Finally, the dye-sensitized solar cell is fabricated using CQD-TiO2 electrode as a photoanode.The performance of DSCs is dependent on the CQD percentage in the electrodes. The power conversion efficiency for DSSC based on TiO2-1.5%CQD films is more than 1.5 times higher than that based on TiO2 alone, indicating that the incorporation of CQD is an efficient means for enhancing the photovoltaic (PV) performance. The better PV performance of CQD-TiO2 DSSC is attributed to the improvement of charge transfer ability of the semiconductor film in the presence of carbon quantum dot wich was verified by electrochemical impedance spectroscopy. The electron lifetime was also investigated using the open-circuit voltage decay (OCVD) technique. The longer electron lifetime was obtained for TiO2-1.5%CQD solar cell.