The role of anchoring groups in ruthenium(II)-bipyridine sensitized p-type semiconductor solar cells—a quantum chemical approach

Ru(II)-bipyridine complexes connected with p-type semiconductors (p-SCs) are promising systems for photocatalytic applications such as in dye-sensitised solar cells. The photosensitizer-semiconductor interface—governed by the anchoring group—is of vital importance for the electronic properties of the systems as it determines the long-term stability to the semiconductor surface through its binding ability and also affects the hole injection from the dye to the semiconductor. In this contribution, the role of the anchoring groups in ruthenium(II)-bipyridine sensitized p-type semiconductor solar cells has been addressed by quantum chemical calculations based on density functional theory (DFT) and time-dependent DFT. Both, the interaction of a series of anchoring groups with a NiO surface, as well as several thermodynamical parameter governing the efficiency of a Ru(II)-bipyridine dye coupled to these anchoring groups have been determined and analysed. Based on these calculations, new anchors for p-SC with improved properties are proposed. In addition, the influence of aliphatic spacers and the presence of solvents on the properties of the anchored Ru(II)-bipyridine complexes are thoroughly addressed. (paper)