ABSTRACT
Photoelectrochemical cells can be used for solar electricity and hydrogen production, computer displays and three-dimensional data storage. Experimental efforts to establish a structural description of the attachment of photosensitizer dyes to an anatase surface have proven inconclusive. The distortion of the anatase structure facing away from the dye molecule is not realistic, because the semiconductor stretches many unit cell lengths both in the two directions along the surface, and down below the surface. The ligand ‘arm’ stretching out from the modified coumarin molecule is bent and rotated with respect to the rest of the molecule, so that a closer contact with the underlying surface atoms becomes possible. Then, the internal structure of both the dye molecule and the anatase lattice are kept fixed, while the minimum energy is sought as a function of the dye distance to the surface, the angle of inclination and rotation of the dye relative to the main lattice directions.
