Pyrrole-based organic dyes for dye-sensitized solar cells

Series of dipolar dyes containing pyrrole-based conjugate spacers between arylamine donor and the 2-cyanoacrylic acid acceptor have been synthesized. These compounds exhibit both pi-pi*and charge-transfer transition in the absorption spectra. Quantum computation results indicate that the pyrrole moieties have larger dihedral angles with its neighboring units, leading to less interaction between the units and, therefore, better charge separation. It also acts as a secondary electron donor upon photoexcitation. The oxidation potentials of arylamine in these compounds are affected by the heteroaromatic conjugated spacers. Dye-sensitized solar cells (DSSCs) using these materials as the sensitizers exhibit good performance, with conversion efficiencies ranging from 4.77% to 6.18%. These values are 66-86% of the standard cell from N719 (7.19%).