Solar fuels that are produced by using abundant molecules (carbon dioxide and water) and sunlight have provided a promising sustainable solution for future energy production. Water-splitting dye-sensitized solar cells utilize semiconductor substrates with high surface areas to incorporate molecular sensitizers and catalysts. The charge transfer processes at the molecule-semiconductor interfaces are crucial to the overall efficiency and performance of these devices. In this dissertation, the interface of molecular sensitizers and the semiconductor electrodes was investigated.In Chapter 1, historical milestones and recent progress in the development of water-splitting dye-sensitized photoelectrochemical cells are summarized. In Chapter 2, the process of interfacial charge transfer at dye-sensitized TiO2 nanowire array electrodes in aqueous electrolytes was studied. This project illustrates the impact of the semiconductor morphology on the charge transport dynamics and recombination rates. In Chapter 3, the solvent effect on interfacial electron injection was studied for dye-sensitized mesoporous TiO2 and SnO2/TiO2 core/shell structures. It was found that changing the dielectric constant of the electrolyte by mixing aqueous and nonaqueous solutions can tune the electron injection efficiency. An injection-induced electric field was found to be present in electrolytes with low ion concentrations and low dielectric constants. This field causes trapping of conduction band electrons at the SnO2/TiO2 interface, resulting in lower overall quantum yields for charge collection. Chapter 4 studied the impact of sensitizer structure and nuclearity on the stability and electron injection efficiency. The study presents the strategy of dimerizing Ru(II) sensitizers that contain various anchoring groups. It was found that dimers with carboxylic acid groups exhibited enhanced stability and the highest injection efficiency. By studying the impact of the morphology of the semiconductor, the solvent, and sensitizer functional groups on the interfacial charge transfer dynamics, we gain insight into the fundamentals of the molecule-semiconductor system. The understanding that is developed not only offers guidance on the future design of better performing photo(electro)catalytic systems for solar fuel production, but also provides useful insights for other photochemical systems that contain a molecule-semiconductor junction.