Dipyrrins, common precursors to porphyrins, exhibit strong light absorption in the visible region and act as anionic ligands towards many metal ions. These characteristics call for the exploration of dipyrrinates as promising ligands for realization of NCS-free Ru-polypyridyl sensitizers for the dye-sensitized solar cell (DSSC). Our initial studies in this direction revealed that the complex [Ru(dcbpy)2(2-tdp)](PF6) (dcbpy = 4,4'-dicarboxylato-2,2'-bipyridine; 2-tdp = 2-thienyldipyrrinate) has an appropriately positioned LUMO for thermodynamically favored electron injection from the excited state of the dye into the conduction band of TiO2, but the energy difference between the LUMO and the bottom of the conduction band is too low, resulting in low values of open-circuit voltage. In order to address this problem, several tris-heteroleptic Ru(II) dipyrrinates have been prepared by replacing one of the dcbpy ligands with a less electron-withdrawing bipyridine or phenanthroline derivative. A new type of Ru-dipyrrinate dyes based on terpyridine ligand was also prepared. In this contribution, we report the synthesis, optical and electrochemical properties, and the DSSC performance of these Ru-dipyrrinate dyes.

Ruthenium(II) dipyrrinates in the dye-sensitized solar cell

245th National Meeting (2013)

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