| Dye-sensitized solar cells have the potential to surpass current photovoltaic technology and meet a large portion of future energy demand. The first four chapters of this work will discuss examinations of the parasitic electron transfers occurring at interfaces that lower overall efficiency. Chapter 1 gives an introduction to dye-sensitized solar cells and relevant electron transfers involved in their function. It further discusses the limitations in current generation dye-sensitized solar cells and methods to circumvent them.;Chapter 2 describes work done on cobalt polypyridyl redox shuttles as alternatives to the standard I3-/I - couple. It is shown that electron transfer from the TiO 2 network to the oxidized form of these shuttles lies in the Marcus normal region. Furthermore, sub-monolayers of alumina deposited onto the interface are shown to fundamentally change the overall mechanism and rate of this interception reaction.;Chapters 3 and 4 discuss the effects alumina and 4-tert-butylpyridine have on electron transfer at the semiconductor-liquid junction in TiO 2 films. It is shown that alumina layers decrease charge injection from the dye, decrease interception by the redox shuttle, and decrease recombination of the injected electron with the oxidized dye molecule. This is accomplished via passivation of defect states on the TiO2 surface. Additionally, it is shown that 4-tert-butylpyridine primarily acts only as a spacer layer on flat TiO2 films, decreasing the rate of interception. On dye-loaded TiO2 nanoparticle films, however, 4-tert-butylpyridine likely also shifts the potential of the sites it affects negatively. The net effect of this shift is a decrease in injection efficiency.;Finally, chapter 5 discusses research in the area of solar fuels. A new atomic layer deposition process is studied. Ferrocene and ozone are used to conformally and precisely lay down thin films of hematite, alpha-Fe 2O3. This process is then used to interdigitate a thin film of hematite over a conductive silica inverse opal framework. The high surface area and small feature size of this setup allow an enhancement of the water oxidation photocurrent generated from hematite thin films. |
