Branched thiophene-based oligomers as electron acceptors in organic photovoltaics

Two branched V-shaped benzo[b]thiophene-based structures were investigated as novel electronacceptor
materials in blended photovoltaic devices. Photoinduced charge transfer was
demonstrated in blends between a regioregular poly(3-hexylthiophene) and the oligothiophenes, via
photoluminescence spectroscopy. The enhanced photovoltaic performance exhibited by the blended
cells, with respect to that of pristine devices in which the polymer was the active layer, represented
further evidence for exciton dissociation. Remarkable improvement of the performance of the
blended devices upon mild thermal annealing was achieved. Furthermore, the effect of the
molecular structure of the branched benzo[b]thiophenes on the blend photoresponse is discussed.