Aza-dipyrrinato ruthenium sensitizers for enhancement of Light-Harvesting ability of Dye-Sensitized solar cells.

Three new aza-dipyrrinato ruthenium sensitizers AZA-BPY, AZA-BPY-NCS, and AZA-TER, have been designed and successfully synthesized. We have studied the effect of aza-dipyrrinato ligands on the photo-physical and electrochemical properties. The aza-dipyrrinato ancillary ligand exhibited enhancement in the light-harvesting capability compared to the traditional dipyrrinato ligand by coordinating ruthenium metal. The strong σ-donor characteristic of the aza-dipyrrinato ligand showed more adequate properties: red-shift in the absorption extended into the NIR region ( ≈ 1000 nm), and redox potentials compared to our earlier reported dipyrrinato sensitizer (GS3), which are confirmed by the UV-Vis absorption spectroscopy and cyclic voltammetry. All the characteristics features shows that these dyes are a good sensitizer candidate for DSSCs.