Structural and electronic properties of dye-sensitized TiO2 for solar cell applications: from single molecules to self-assembled monolayers

We review computational contributions to the understanding of the physical principles underlying interface phenomena related to dye adsorption at the surface of titanium oxide, within the scope of dye sensitized solar cell applications. We focus our attention on the theoretical studies aimed at computationally representing dye-sensitized solar cells under realistic conditions, e.g. by including the solvent and the electrolyte in interactions with dye-sensitized TiO2 through protocols accounting for thermal nuclear motion. The impact of dye clustering and self-aggregation into monolayers on the optical and transport properties of dye-sensitized TiO2 is addressed. Computational studies of surface protonation, charge and energy-transfer, or the influence of the presence of additive agents or co-sensitizers are also reviewed in relation to the electronic, spectroscopic, kinetic and diffusion properties of self-assembled dye monolayers sensitizing TiO2.