The development of efficient, affordable solar cells for clean energy production is a major global challenge and in this proposal we are seeking to achieve a breakthrough in the fabrication of novel quantum dot materials capable of substantially improving the performance of III-V solar cells based on GaAs. We propose a close collaborative project with Nelson Mandela Metropolitan University in South Africa, who have complementary expertise in photovoltaic cells, to develop and characterize hitherto unexplored GaSbN/GaNAs type-II quantum dot materials. These strain-compensated, dilute-nitride quantum dots will be implemented within the active region of prototype GaAs based solar cells to significantly extend the spectral response and improve the efficiency. This would lead to a new generation of solar cells for clean electricity generation. Feedback from device studies will provide valuable insight into the photovoltaic properties of these unique nanostructures, further aiding material optimization. The quantum dot materials that we shall develop here could either be used to increase efficiency in single junction cells, or could be incorporated into existing multi-junction cells to replace expensive Ge substrates, reduce cost and significantly increase performance. There are clear opportunities for uptake of the technology both within South Africa and the UK.