Novel DCM-based organic dye with a heteroleptic dual-electron donor for dye-sensitized solar cells

A new DCM-based organic dye with a heteroleptic dual electron donor was designed and its electronic and optical properties were investigated theoretically for dye-sensitized solar cells (DSSCs). In this study, heteroleptic Dab dye was compared with other homoleptic dyes (Daa and Dbb). To gain insight into the factors responsible for photovoltaic efficiency, density functional theory (DFT) and time-dependent density functional theory (TDDFT) calculations of these dyes were conducted. It showed that Dab dye is available as a photovoltaic device from the energy diagram for the TiO2 electrode and the iodide electrolyte. It also showed that although Dab dye produces slightly stronger absorption at above 600 nm, Dbb dye would show a better overall absorption property. Owing to the strong electron density and high proximity of its anchoring carboxylic group to LUMO + 1 and LUMO, however, it is expected that Dab dye with a heteroleptic dual donor will show a competitive performance compared to other dyes with homoleptic dual donors in the conversion efficiency for DSSCs.