Abstract:
Photovoltaic technology is the most promising alternative to ever exhausting energy resources. However, this form of energy is expensive because of the cost and processing associated with commercialization. In this regard, organic solar cell can be effective since the processing of this kind is cheaper and easier. Nevertheless, organic solar cell research still requires much attention to reach the performance level of inorganic solar cells. In this thesis, we propose a detailed FDTD model to describe upconversion in organic solar cells (OSC) and analyze upconversion process for P3HT:PCBM, PSBTBT:PCBM, PBDTTT-C:PCBM and PTB7-Th:PCBM based OSCs, having different power conversion efficiency (PCE) ranges. For each OSC, our model predicts significant improvement in PCEs when an optimized upconverting layer is attached at the back end of the solar cell. For the most efficient active material PTB7-Th:PCBM, a maximum 17% enhancement in PCE has been recorded. In a separate study, we propose a design of metallic nanowire incorporated PTB7-Th:PCBM solar cell and show that up to 13% enhancement in PCE is possible by introducing plasmonic effect at two distinct wavelengths. Then, we analyze the combined effect of plasmonic resonance and upconverting layer in PTB7-Th:PCBM solar cell and estimate a mere 5% enhancement from individual effect. Finally, we discuss the possibility of stretching the PCEs of upconverting OSCs by utilizing concentrated sun light illumination. At 10 sun illumination, it is possible to enhance PCE beyond 50%. The model developed and results obtained from the study have important implications in current OSC research.
