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International Journal of Photoenergy
Volume 2012 (2012), Article ID 524590, 8 pages
http://dx.doi.org/10.1155/2012/524590
Research Article

Photocatalytic Oxidation of Triiodide in UVA-Exposed Dye-Sensitized Solar Cells

SPECIFIC, College of Engineering, Swansea University, Baglan Bay Innovation Centre, Central Avenue, Baglan Energy Park, Baglan, Port Talbot SA12 7AZ, UK

Received 14 September 2011; Accepted 27 October 2011

Academic Editor: Jiaguo Yu

Copyright © 2012 Matthew Carnie et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

UVA irradiation of glass mounted dye-sensitized solar cells without UV filtration causes failure within 400 hours of light exposure. The failure mode is shown to relate to consumption of I 3 , which is directly related to TiO2 photo-catalysis. The onset of failure is easily determined from electrochemical impedance data where the recombination resistance of the TiO2/electrolyte back reaction drops markedly prior to the onset of degradation. At the point of complete cell failure this impedance value then dramatically increases as there is no longer an interfacial reaction possible between the TiO2 and the I 3 depleted electrolyte. Device failure is most rapid for cells under electrical load indicating that the degradation of the electrolyte is related to photogenerated hole production by excitation of the TiO2. Once depleted by UV exposure, the I 3 can be regenerated by simple application of a reverse bias which can restore severely UV degraded devices to near original working conditions.