Dye-sensitized solar cells have been studied for many years as a potential inexpensive and scalable alternative to silicon solar cells. They have recently expanded their list of photosensitizers to include quantum dots. In recent years, there has been substantial progress in the field of quantum dot solar cells, with certified efficiencies now reaching 13.4%. Fundamental studies on nanomaterial/semiconductor electrode coupling have led to a deeper understanding of photoinduced electron-transfer processes that are important for both of these devices. This Feature Article will highlight the use of a model system, nanomaterials sensitizing single-crystal oxide substrates, that is useful for investigating how changes in nanomaterial shape, dimensionality, size, and local environment affect the photoinduced charge separation efficiency.