  Exciton dissociation and recombination in polyoxotitanate clusters, Ti17cat4 and Ti17 was investigated by ultrafast spectroscopy. The clusters offer a fascinating bridge between ET in small molecules and interfacial ET in dye-sensitized anatase nanoparticles. Depolarization experiments suggest that the exciton rapidly evolves into the charge-separated state. The spectral component assigned to the injected electron depolarizes within <100 fs. The component associated with the hole localized on the catechol ligand undergoes slower depolarization (~2 ps), consistent with hopping between four degenerate catechol sites. The observed hole dynamics agrees remarkably well with the results of modeling. The decay of the CS state exhibits three rates. The fastest corresponds to geminate recombination and the intermediate to the bulk process. The third, slowest rate may indicate the involvement of �dark� states, i.e. triplet polaron-excitons.

Exciton and polaron dynamics in polyoxotitanate clusters: Are these very large molecules or very small nanoparticles?

244th National Meeting (2012)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.