Over the past two decades dye sensitized solar cells have evolved from fascinating science to a potentially viable source of renewable energy. This dissertation investigates barriers preventing dye-sensitized solar advancement: mainly interfacial electron-transfer reactions from nanoparticle TiO2 films to redox shuttles (i.e. recombination). The focus is on the use of outer-sphere redox couples to perform systematic investigations of recombination reactions. A primary example is a system of cobalt(III/II) tris-bipyridyl complexes. The resulting detailed representation of electron transfer at the semiconductor/liquid interface in dye sensitized solar cells is presented. The result of these studies allowed for the development of a relatively simple model based in Marcus Theory to predict the efficiency of DSSCs as a function of redox couple potential and reorganization energy. Also presented is a novel variable temperature spectroelectrochemical method to measure the conduction band energy in mesoporous semiconductor electrodes that became necessary to develop during the course of this work. In addition, methods of controlling recombination and overcoming mass transport limitations which can lead to high-efficiency solar cells are discussed.
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