"The multicomponent design of DSSCs provides the opportunity of integrating cheap materials for efficient power generation and has significant advantages over conventional silicon photovoltaics (PVs). By separating the processes of absorption, charge separation and charge collection through the use of a molecular sensitizer, a wide bandgap semiconductor and redox shuttle, dye cells are highly tunable for conducting fundamental studies leading to device optimization. Given the synergy of charge-transfer among these three components is pivotal for maximizing device performance, this dissertation will focus on understanding charge-transfer relative to the pathways of recombination and regeneration, which limit DSSC efficiencies. Use of one-electron outersphere redox shuttles (OSRSs) has provided a viable route for describing such pathways in operating dye cells through the application of Marcus Theory. A central theme has been to design novel low-spin (LS) cobalt OSRSs, which employ fast self-exchange kinetics and low reorganization energies, in an effort to optimize rates of regeneration. It is evident, however, that a balance must be struck between the reorganization energy of the redox shuttle and the driving force for recombination. We address this issue through a series of external quantum yield measurements in Chapter 3 and seek to remedy the problem by either using a tandem electrolyte as in Chapter 4 or by integrating redox shuttles with highly negative formal potentials to regenerate near IR absorbing sensitizers as in Chapter 5."--Page ii.
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