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Degradation mechanisms in a dye-sensitized solar cell studied by UV–VIS and IR spectroscopy

✍ Scribed by Helena Greijer Agrell; Jan Lindgren; Anders Hagfeldt


Publisher
Elsevier Science
Year
2003
Tongue
English
Weight
487 KB
Volume
75
Category
Article
ISSN
0038-092X

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✦ Synopsis


By deliberately causing degradation of components in a dye-sensitized solar cell we have studied failure mechanisms of such cells. The dye, bis(tetrabutylammonium) cis-bis(thiocyanato)bis(2,2 0 -bipyridine-4-carboxylic acid, 4 0 -carboxylate)ruthenium(II), adsorbed to a nanostructured TiO 2 film was studied with UV-VIS and IR spectroscopy after being exposed to visual and ultra-violet radiation, increased temperature, air, electrolyte, and water in the electrolyte. The thiocyanate ion ligand is lost in air, at temperatures equal to and above 135 °C, in electrolyte and possibly upon UV irradiation. The loss of the SCN À ligand in air was accelerated under visual illumination. From working electrodes immersed in the electrolyte or in degraded complete solar cells it was observed that the absorption peak from the thiocyanate ion ligand at around 2100 cm À1 had broadened, blue-shifted and decreased. One failure mechanism is thus that the thiocyanate ion ligand is lost from the dye together with the electrolyte. Together with water in the electrolyte (5 v%) the SCN À ligand is exchanged with H 2 O and/or OH À . The ligand exchange between SCN À and H 2 O/OH À was accelerated under visual illumination.