A low-cost, high-efficiency solar cell based on dye-sensitized colloidal TiO2 films

A photovoltaic cell created from low- to medium-purity materials by low-cost processes is described which exhibits a commercially realistic energy-conversion efficiency. The device is based on a 10-micron thick optically transparent film of titanium dioxide particles a few nm in size, coated with a monolayer of a charge-transfer dye to sensitize the film for light harvesting. The device harvests a high proportion of the incident solar energy flux and shows exceptionally high efficiencies for the conversion of incident photons to electrical current. The overall light-to-electric energy conversion yield is 7.1-7.9 percent in simulated solar light and 12 percent in diffuse daylight. The large current densities and exceptional stability as well as the low cost make practical applications feasible.