Characterization of a Porphyrin-Containing Dye-Sensitized Solar Cell

The photovoltaic performance of several porphyrin-derivatized TiO2 films in regenerative photoelectrochemical cells is reported and compared to that in cells sensitized with a Ru(2,2‘-bipyridyl-4,4‘-dicarboxylate)2(NCS)2 (N3) dye. The porphyrin sensitizers tetrakis(3‘,5'-di-tert-butylphenyl)porphyrin, tetrakis(3‘,5‘-di-tert-butylphenyl)porphyrin zinc(II), and tetrakis(4'-carboxyphenyl)porphyrin were studied. Differences in efficiencies of the porphyrin light absorbers are ascribed to poor electronic coupling of the latter two sensitizers to the titania conduction band. Dark currents and I−V curves were measured as a function of incident ligth intensity and I3-/I- electrolyte concentrations for three different film preparations, with and without a coadsorber. Analysis of dark current results with use of a perviously proposed model suggests that the lower efficiencies yielded with P25 TiO2 supports compared to semitransparent electrodes can be explained, in part, by the differneces in the measured back elec...