Nanostructured materials for solar-to-electric energy conversion

Solar cell architectures based on nanostructured materials are proposed and the scientific and engineering problems that must be overcome to bring them closer to commercialization are discussed. Foremost among the new cell designs are the dye sensitized solar cells (DSSC) and polymer heterojunction polymer solar cells. In a DSSC, a monolayer of a photosensitive dye is adsorbed on a mesoporous nanocrystalline semiconductor, usually TiO₂, in the presence of an electrolyte. Photons are absorbed by the dye to excite electrons from the HOMO to the LUMO level and the excited electrons are rapidly injected into the TiO₂. To overcome the shortcomings of the present design, increase the cell efficiency, and reduce manufacturing cost, TiO2 nanoparticles were replaced with ZnO nanowires produced by low temperature solution growth methods. ZnO nanowires, grown on transparent conducting oxide substrates from aqueous solutions of Zn(NO₃)₂ and methenamine at < 100°C provide a morphology suitable for use as the photocathode in dye-sensitized and quantum-dot-sensitized solar cells. This is an abstract of a paper presented at the AIChE Annual Meeting (San Francisco, CA 11/12-17/2006).