With the intensifying global need for alternative energy, there is strong interest in new approaches to materials for sustainable energy devices. A variety of different energy technologies must work in concert to produce, store, and consume the 20 TW of energy that humans will soon demand. Underlying the diverse set of energy conversion devices are similar physical and chemical phenomena, many of which can be controlled with nanoscale materials. This talk will describe research on nanoscale materials for solar photovoltaics and solar fuel production. Synthetic strategies including atomic layer deposition are used to generate nanoscale materials with a high level of control over composition, structure, and thickness. The materials are then tested in energy conversion devices. The prospects and challenges for such materials to contribute to higher energy conversion efficiencies will be discussed.