Theoretical Study on the Structural and Optoelectronic Properties of Mix Diimine-Dithiolate Complexes with the Group VIII Metals for Application in DSSCs

In this research, the structural, electronic and optical properties of mix diimine-dithiolate complexes with general formula [M(diimine)(dithiolate)] (M = Ni, Pd, Pt; diimine = phenanthroline)phen(;dithioalt = 1,2-benzenedithiolate) bdt), maleonitriledithiolate (mnt)) are reported through density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations. Natural Bond Orbital (NBO) analyses are also performed for scrutinizing the structural properties of the considered complexes. The results show that the M–S bond has a stronger covalent character than the M–N bond and is always polarized towards the sulfur atom. The absorption spectra of these complexes were obtained by using the time-dependent density functional theory associated with the polarized continuum model (PCM). Obtained results indicate that the substitution of bdt ligand and Pt metal enhances the intensity of the absorption significantly and the overall absorption spectrum can be red-shifted. Moreover, the latter complex [Pt(phen)(bdt)] has the highest light-harvesting efficiency (LHE). Overall, this study can widen for diimine- dithiolate complexes with a suitable combination of metal ions and ligands to be explored as dye-sensitized solar cells.