Investigation of the effect of alkyl substitution on DSSC efficiency of Ru(II) complexes bearing tridentate benzimidazole ligands

Abstract

In this study, tridentate 2,6-bis(5,6-dimethyl-1H-benzimidazol-2-yl)pyridine ligand (L1) and eight derivatives (L2–9) were prepared by substitution with alkyl chains and Ru(II) complexes of these ligands (C1–9) were synthesized. The synthesized ligands and their Ru(II) complexes were characterized by FTIR, UV–vis, 1H-NMR, and ESI/MS spectroscopic methods. The absorption and the emission spectra of the complexes were examined, HOMO–LUMO energy levels of the complexes were determined by cyclic voltammetry and their use as photosensitizer in dye-sensitized solar cells (DSSCs) was investigated. The effects of alkyl chain substitution on absorption in the visible region and on the current–potential characteristics of the complexes are discussed. The effects of this modification on the important parameters for DSSCs such as absorption, current density were examined and power conversion efficiency values of the Ru(II) complexes are reported.