Long-lived charge separated state in molecular films containing porphyrin–fullerene dyad

A photoinduced interlayer charge separation in bilayered molecular film, constructed by the Langmuir–Blodgett technique, was demonstrated. The lifetime of the primary charge separated state in a monolayer of porphyrin–fullerene dyad, P–F, was found to be in a microsecond time domain, and was increased due to the secondary electron transfer from polythiophene, PHT, to the porphyrin cation of the dyad. In the final state positive charges are located at the PHT layer and negative charges in the fullerene network, yielding the long lifetime, about 150 μs, in the final interlayer charge separated state.