A DFT study of adsorption of perylene on clean and altered anatase (101) TiO2

The adsorption of perylene equipped with a carboxylic acid anchor on a titanium dioxide anatase (101) surface was studied through density functional theory calculations. The binding of dye molecules, of which organic species are frequently modelled with perylene, is a crucial aspect in the development of efficient dye-sensitized solar cells. Two different monodentate binding modes and a bidentate mode are considered on a clean surface as well as on surfaces with a coadsorbed dissociated water molecule or an oxygen vacancy. It was concluded that monodentate adsorption is favored in all cases. Also, the modifications to the surface considered here have an additive effect on the adsorption energy. The effect of a water molecule is ∼0.1 eV, while a surface oxygen vacancy increases adsorption energies by 0.6 eV-0.8 eV. Partial and complete deprotonation was discovered in some cases for non-dissociative adsorption geometries, indicating that the hydrogen atom travels between the molecule and the surface.