Synthesis and characterization of a series of cobalt complexes: Investigation of their efficacy as sensitizers in dye-sensitized solar cell applications

Abstract

A series of cobalt(II) complexes possessing diverse structural and electronic properties were prepared by using varieties of ligand systems. All the complexes were thoroughly characterized by spectral and analytical and techniques including X-ray crystallography and the molecular structures were optimized by DFT studies (M06 & B3LYP methods). The theoretical HOMO-LUMO energy gaps were compared with the optical band gap energies calculated using Tauc plot. Utility of the prepared cobalt (II/III) complexes as sensitizers in the dye-sensitized solar cell was investigated. I–V parameters of the fabricated solar cells were noted and compared with the cell made using standard N719 dye. Among the twenty-one complexes investigated, complex C4, comprising of bis(pyrazolyl)methane ligands exhibited highest power conversion efficiency.