Ternary porphyrinoid:polymer:fullerene bulk heterojunction organic solar cells

This thesis will investigate how porphyrinic materials may be successfully incorporated into polymer/fullerene organic solar cells to broaden light absorption, enhance power conversion efficiency, and to further probe and broaden the understanding of the chemistry and physics of both binary and ternary blended organic solar cells. This thesis will begin with a discussion of bulk heterojunction organic solar cells, and how porphyrinic materials can be incorporated into these devices to form ternary blends, including a review of the ternary polymer:porphyrinoid:fullerene literature published to date. The performance of standard MEH-PPV:PCBM organic solar cells manufactured at the University of Newcastle during the course of this PhD will be examined to show how device efficiency has steadily improved over the course of the project (2007-2011). Furthermore, it will show that the incremental improvements made to the standard binary devices over time are directly transferable to ternary blend devices. The effect of systematically changing the steric bulk of a porphyrin on the performance of ternary blend devices is then investigated, as is the effect of changing the electronic states of the core while maintaining a constant steric profile. The effect on device performance of varying the para-phenyl substituents of a series of tetraphenylporphyrin derivatives is also examined. Finally, the effect of altering the central metal cation in a series of metalloporphyrins with octaethylporphyrins and tetraphenylporphyrins ligands is investigated. This thesis as a whole provides an insight into the chemistry and physics of ternary blend organic solar cells, detailing not only the interaction of porphyrin with polymer and fullerene, but also the effects of porphyrin-porphyrin interactions and how these may be controlled. Steric, electronic, and morphological effects are investigated, to provide a comprehensive study of ternary blend organic solar cells.