This thesis presents two models of a dye-sensitized solar cell (DSC): diffusion model and electrical model. The main purpose is to investigate interfacial charge transfer and charge transport within the semiconductor/electrolyte layer under illuminated conditions. These two interrelated models confirm that diffusion is the major driving force for electron and ion transport, while the drift of electrons is negligible. The diffusion model was utilized to simulate the temperature influence on the overall efficiency of DSC with a consideration of the voltage loss at titanium dioxide (TiO2)/ transparent conductive oxide (TCO) interface. It reveals that low temperature conditions have serious detrimental effects on the DSCs' performance. Further the electrical model was used to analyze the effect of diffusion/drift, dye loading, and electrode thickness on DSC performance. The predicted optimal electrode thickness ranges between 10-15 μm which is consistent with the thickness (10 μm) used in experimental studies published in the literature.