Visible Light Sensitization of TiO₂ Surfaces with Alq3 Complexes

We combine ab initio DFT molecular dynamics simulations and quantum dynamics propagation of transient electronic excitations to investigate visible light sensitization of TiO2-anatase surfaces by covalent attachment of derivatized aluminum tris-(8-hydroxyquinoline) (Alq3) complexes. Hydroxylated arylquinoline and benzoquinoline ligands are introduced as robust anchoring groups to form Alq3/TiO2 molecular assemblies. We show that photoexcitation of the resulting surface complexes with visible light triggers ultrafast interfacial electron injection into the TiO2 host substrate. Furthermore, we show that derivatization of the Alq3/TiO2 surface complexes with oligothiophenes should hinder electron−hole pair recombination after photoinduced interfacial electron transfer. These findings are particularly relevant to the development of molecular based photo-optic devices based on the general class of metaloquinolate complexes Mq3, with q = 8-hydroxyquinoline and M = Al, Zn, Ga, and In, which have already attracted significant interest in the development of new technologies.