Preventing UV Degradation in Dye Sensitized Solar Cells

The effects of a UV cut-off filter and a UV additive on the stability of dye-sensitized solar cells were studied. Both approaches to prevent UV, which is a major degradation factor, have been presented in literature, but the effectiveness of these measures have not been compared nor their possible combined effect to reach even higher UV protection tested. Here, the studied cells had conventional iodine based electrolyte or electrolyte with cobalt complex redox couple to which the UV absorber (benzophenone based) was mixed. The cells were subjected to an accelerated aging test using a UV light and the cells with no protection were compared to cells with those having the UV absorber and/or a UV cut-off filter. The initial and final performance of cells were characterized by photovoltaic measurements, electrochemical impedance spectroscopy, and other measurement techniques. The cobalt based cells showed faster degradation compared to iodine based cells, even with the UV filter and their degradation could be related to the degradation of the organic dye. The performance of the iodine based cells remained stable over 111h when a UV cut-off filter was applied. Our study also shows that the UV filter has a superior effect in blocking UV light, whilst the UV additive had only a marginal effect at most in stabilizing the cells.