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

• Published in: Nature (London) 1991-10, Vol.353 (6346), p.737-740
• Main Authors: O'Regan, Brian, Grätzel, Michael
• Format: Article
• Language: English
• Subjects: Applied sciences; Energy; Exact sciences and technology; Humanities and Social Sciences; letter; multidisciplinary; Natural energy; Photovoltaic conversion; Science; Science (multidisciplinary); Solar cells. Photoelectrochemical cells; Solar energy
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/353737a0

THE large-scale use of photovoltaic devices for electricity generation is prohibitively expensive at present: generation from existing commercial devices costs about ten times more than conventional methods 1 . Here we describe a photovoltaic cell, created from low-to medium-purity materials through low-cost processes, which exhibits a commercially realistic energy-conversion efficiency. The device is based on a 10-µm-thick, optically transparent film of titanium dioxide particles a few nanometres in size, coated with a monolayer of a charge-transfer dye to sensitize the film for light harvesting. Because of the high surface area of the semiconductor film and the ideal spectral characteristics of the dye, the device harvests a high proportion of the incident solar energy flux (46%) and shows exceptionally high efficiencies for the conversion of incident photons to electrical current (more than 80%). The overall light-to-electric energy conversion yield is 7.1-7.9% in simulated solar light and 12% in diffuse daylight. The large current densities (greater than 12 mA cm -2 ) and exceptional stability (sustaining at least five million turnovers without decomposition), as well as the low cost, make practical applications feasible.