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.