A core-modified porphyrin as a sensitizer for dye-sensitized solar cells

A core-modified porphyrin was used as a light harvesting sensitizer for dye-sensitized solar cells (DSSC). The substitution of one nitrogen atom to sulfur atom at the core aromatic system in the porphyrins resulted in the red-shift of porphyrin in UV-Vis spectrum. Two carboxylic acid groups can bind strongly to the surface of an oxide semiconductor, (e.g. TiO{2}). The solid film of porphyrin gave band I absorption with λ_max of 695 nm. DSSCs were fabricated with a core-modified porphyrin and a nanocrystalline porous TiO₂ layer deposited on fluorine-doped tin dioxide (FTO) glass. The amount of porphyrin attached onto TiO₂ surface depended on the concentration of a porphyrin solution. As the solution concentration increased, more porphyrins were absorbed onto the TiO₂ surface and the DSSC performance was improved. There was a direct relationship between the concentration of porphyrin solution and the cell performance.