Song, Keping2013-04-152013-04-152013-02https://hdl.handle.net/11299/147625University of Minnesota M.S. thesis. February 2013. Major: Mechanical Engineering. Advisor: Tianhong Cui. 1 computer file (PDF); vi, 44 pages.Nowadays, people are focusing on research and development of some different kinds of solar cells as replacements for silicon based solar cells (SSCs) by using alternative technologies and low-cost materials. Polymer solar cells (PSCs) and dye-sensitized solar cells (DSCs) have been considered as promising replacements. In the last twenty years, a significant progress has been made on the improvement of the power-conversion efficiency (PCE) for both polymer and dye-sensitized solar cells, and the achieved efficiencies have evolved to around 9% for PSCs and 12% for DSCs as reported recently. However, the efficiency of polymer solar cells is still significantly lower than the traditional inorganic SSCs, which nowadays has reached nearly 26%. In order to further optimize the performance of polymer and dye-sensitized solar cells and eventually reach the goal PCE for commercialization of nearly 15%, support and guidance from theoretical modeling will be required. Hence, in this thesis, we have achieved the ultimate efficiency of the structured polymer solar cells by using the model based on Marcus theory of electron transfer. By choosing different active layer materials, the upper limits of efficiency in these various polymer solar cells were calculated. Besides, we combined the light absorption coefficient into calculation, the ultimate efficiencies were largely affected, and more accurately, were significantly deduced. These results showed better approximation to the real experimental cases. The dye-sensitized solar cells were fabricated by a layer of highly porous nanocrystalline TiO2 in association with a traditional ruthenium dye as sensitizer to form the anode electrode and a layer of structured platinum/ITO as the cathode back contact. By using modeling process along with the combination of light absorption coefficient, the ultimate efficiencies for DSCs with different back contact structures were achieved. The enhanced performance compared with the traditional non-structure cells in ultimate efficiency was clearly demonstrated and can be explained by theoretical analysis.en-USThesis or Dissertation