NSF-European Materials Cooperative Activity. "Nanostructured oxide thin films for organic/inorganic solar cell applications"

The advancement of renewable energy technology has become increasingly critical to meet growing worldwide energy needs while minimizing greenhouse gas release. Although the field of photovoltaics has continually evolved over the last decades, researchers are looking beyond current device designs to what have been termed third-generation technologies. These technologies are aimed at improving efficiency, reducing cost, or ideally both. To realize these goals, many of these technologies will utilize nanostr utured materials and composite systems that can be tailored to have optimized electronic and optical properties. Organic/inorganic composite materials are a promising route to meeting these needs. Solar cells based on blends of nanostructured oxides and p olymers have achieved efficiencies exceeding 3%. This is an encouraging value, but a substantial increase in performance is required for these devices to be of practical use. To achieve higher efficiencies requires control of the morphologies of the polym er donor and oxide acceptor materials to optimize photogenerated charge collection. Good mechanical contact and adhesion between the organic and inorganic components must be achieved. The relative electronic levels of the two materials must be optimized t o facilitate interfacial exciton dissociation and charge transfer. The orientation of the nanostructures must be precisely engineered to optimize collection at the contacts. The proposed project will grow and characterize oxide nanorod array thin films us ing pulsed laser deposition. State-of-the-art optical and electron diffraction/spectroscopy will be performed. In collaboration with our US partner, our materials will be used to develop systematic surface modification strategies to improve charge transpo rt between organics and inorganics. The project initiates a new international collaboration with the Colorado School of Mines, US, through exchange of information, samples and personnel.