Triphenylamine-functionalized corrole sensitizers for solar-cell applications

New corrole sensitizers having a triphenylamine moiety at the meso position and a carboxylic anchoring group at the pyrrole-beta position, in both free-base and copper complex forms, have been designed, synthesized, and tried as sensitizers in dye-sensitized solar cells. All the substituted carboxy-corroles were completely characterized from structural, optical and electrochemical points of view. Computational investigations by means of density functional theory (DFT) and time-dependent-DFT (TD-DFT) calculations have been carried out, in order to give a deep insight into the charge-injection process. Quite low photovoltaic performances were obtained, particularly for the investigated copper complexes, possibly due to an unfavorable energy-level alignment between the dye's injecting states and TiO2 conduction band, limiting the charge injection and thus the photocurrent extracted from the devices. Our study may provide the guidelines for future development of more efficient solar-cell sensitizers.