A combined molecular dynamics and computational spectroscopy study of a dye-sensitized solar cell

An organic dye-sensitized solar cell consisting of a squaraine molecule attached to a TiO2 surface is modeled using first-principles molecular dynamics and time-dependent density functional theory. The system is surrounded by solvent molecules that are treated at the same level of theory as the dye molecule and the surface. The effect of the solvent on optical properties is investigated by computing many absorption spectra for various configurations along a molecular dynamics trajectory. It is shown that the dynamical effects induced by thermal fluctuations have a strong effect on the optical properties and that satisfactory agreement with experiments is achieved only when those thermal effects are accounted for explicitly.