Zinc-porphyrin dyes with different meso-aryl substituents for dye-sensitized solar cells: experimental and theoretical studies.

A series of new zinc-porphyrin dyes that contain different meso substituents (phenyl, carbazole phenyl, and carbazole thiophenyl groups) and bithiophenyl cyanoacrylic acid as the π-conjugated anchoring moiety were designed, synthesized, and characterized as sensitizers for dye-sensitized solar cells (DSSCs). The effects of these meso substituents on the properties of the porphyrin dyes were theoretically and experimentally investigated. By meso substitution of the porphyrin ring with carbazole-aryl moieties, the short-circuit current (Jsc ) and open-circuit voltage (Voc ) of the DSSCs were improved as was the power conversion efficiency (η) owing to the influence of both the suppression of dye aggregations and the enhanced charge separation and charge-injection efficiency of the dye to TiO2 films. Among these dyes, ZnPCPA made of the carbazole phenyl meso substituents gave rise to the highest η of 6.24 % (Jsc =13.38 mA cm(-2) , Voc =0.66 V, and fill factor of 0.71).