Vectorial photoinduced electron transfer of phytochlorin-fullerene systems in Langmuir-Blodgett films

Abstract

Molecular systems capable of photoinduced vectorial electron transfer (ET) were assembled using the Langmuir-Blodgett technique. The active part of the systems consisted of phytochlorin-fullerene donor-acceptor layers and polythiophene secondary donor layers. Such structures can promote multi-step inter-layer ET in a direction determined by the film architecture. Transient photovoltage and photocurrent were studied and ET rates and efficiencies were determined. The primary intramolecular charge separated state was formed upon photoexcitation in less than 1 ns and it recombined in approximately 50 ns. Addition of the polythiophene layer at the side of the phytochlorin moieties increased the distance of charge transfer and the lifetime of the charge separated state by promoting spontaneous interlayer electron transfer from the polymer to the phytochlorin cation.