Active Layer Modification of Organic Photovoltaics - Studying Structural Impacts of Conjugated Polymer and Using Nanowires as Electron Transport Pathways

The potential of organic photovoltaics (OPVs) to be a low-cost and low-carbon renewable energy source has generated great interest in this field over the last decade. To obtain OPVs with higher efficiency, efforts have been devoted to improving the properties of the active layer materials (the conjugated polymers and n-type materials), improving the fabrication processes, and understanding the many operating mechanisms. Besides the intrinsic materials properties, the morphology of the active layer has also been found to dramatically affect the performance of OPVs. Among these studies, two strategies are often used to develop OPVs with higher efficiency: (1) Develop new device structure; (2) Design and synthesize conjugated polymer with better properties for OPV application. In this thesis, a project based on each strategy will be discussed. The first strategy leads to a serial studies and process method developments on using inorganic nanomaterial as charge transport pathways in OPVs (Chapter 2). On the other hand, as understanding the structure-property relationship of conjugated polymers is very helpful in using the second strategy to improve OPVs, two different structures -- silafluorene containing multi-fused heptacylic arenes as the donor in donor-acceptor conjugated polymer and fluorine substituents on the conjugated polymer backbone will be included in Chapter 3.