title: Theoretical insight on novel donor-acceptor exTTF-based dyes for dye-sensitized solar cells.
abstract: A thorough density functional theory study is performed for the three carboxyl-based derivatives of the exTTF-TCF chromophore, where the π-extended tetrathiafulvalene (exTTF) electron-donor is linked to the tricyanofuran (TCF) electron-acceptor through an ethylene bridge, as dyes for dye-sensitized solar cells. Calculations predict that the carboxyl group in the acceptor moiety adopts an adequate orientation for an efficient anchoring on the semiconductor TiO₂ surface. The carboxylic acid group holds a negative charge twice larger than the cyano moiety that favors the electron injection to the semiconductor. Time-dependent calculations allow for the assignment of the absorption bands in the UV-vis spectrum of exTTF-TCF and confirm the presence of two low-lying charge-transfer electronic transitions that account for the moderately-intense absorption in the 450-800 nm range. The striking optical absorption properties of exTTF-TCF are preserved for the carboxylic analogues. Finally, periodic calculations show relevant topological differences between the carboxylic derivatives anchored on the TiO₂ surface, which would notably influence in the power conversion efficiency of a dye-sensitized solar cell.
authors.affiliation: Instituto de Ciencia Molecular, Universidad de Valencia, 46980, Paterna, Spain.
authors.forename: Joaquín
authors.initials: J
authors.lastname: Calbo
authors.forename: Pedro M
authors.initials: PM
authors.lastname: Viruela
authors.forename: Enrique
authors.initials: E
authors.lastname: Ortí
mesh_terms: D001674:Bioelectric Energy Sources; D006571:Heterocyclic Compounds / Q000737:chemistry*; D008962:Models, Theoretical; D012993:Solar Energy
chemical_list: D006571:Heterocyclic Compounds; C063887:tetrathiafulvalene