Highly stable sensitizer dyes for dye-sensitized solar cells: role of the oligothiophene moiety

The photostability of five sensitizer dyes with and without an oligothiophene moiety was studied by means of spectroscopic techniques to determine the dyes' suitability for dye-sensitized solar cells. We examined the effect of light irradiation on the dyes adsorbed on nanocrystalline TiO2 films under ambient conditions and found that the dyes containing an oligothiophene moiety showed high stability. The results of transient absorption measurements suggest that the location of holes on the oligothiophene moieties was responsible for this observed high stability.