Efficiency enhancement of dye-sensitized TiO₂ solar cell based on ruthenium(II) terpyridyl complex photosensitizer

We theoretically investigated the influence of the ligands on the enhancement of the efficiency toward absorption in the solar spectrum of ruthenium(II) terpyridyl complex. In the present work, the NCS ligands of the parent black dye 4,4′,4″-tricarboxy-2,2′:6′,2″-terpyridine)ruthenium(II) complex (BD0) were kept unchanged, while π-conjugating spacers were introduced between the terpyridine ligands and the anchoring groups -COOH. Molecular structures, electronic, and spectroscopic properties of four designed black dyes, in addition to the parent black dye (BD0), were examined. Compared with the parent black dye BD0, broad and intense absorption bands in the infrared and near-infrared region (red-shifted) were found, featuring the enhancement of the absorption efficiency resulting from the insertion of the proposed π-conjugating spacers.