Push-pull porphyrins for efficient dye-sensitized solar cells

Dye-sensitized solar cells (DSSC) have attracted much attention because they present a highly promising alternative to conventional photovoltaic devices based on silicon [1-3]. In nanocrystalline TiO₂ solar cells sensitized with a dye, efficiencies of conversion of light to electric power up to 11% have been obtained with polypyridyl ruthenium complexes [4, 5]. The advantages of using such ruthenium complexes are that they exhibit broad absorption in the near UV and visible regions and appropriate excited-state oxidation potentials for electron injection into the conduction band of TiO₂ [6]. The cost, rarity, and environmental issues of ruthenium complexes limit their wide application and encourage exploration of cheaper and safer sensitizers.