Abstract :
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(2,20-bipyridine-4-carboxylic acid, 40-carboxylate)
ruthenium(II), adsorbed to a nanostructured TiO2 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 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 1 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 ligand is exchanged with H2O and/or OH . The ligand exchange between SCN and H2O/OH was
accelerated under visual illumination.
2003 Published by Elsevier Ltd.
