Organic photovoltaic cells with structured interfaces: Columnar-grain active layers made of cross-linked semiconducting polymers

We report on organic photovoltaic cells (OPVs) with columnar-grain active layers consisting in cross-linked semiconducting (conjugated) polymers as electron-donors and PCBM as the electron-acceptor and compare with OPVs based either on blends or on planar bilayers made with the same components. Although the columnar-grain layers have morphologic characteristics still far from ≪optimal≫ for PV operation, we found a significant improvement in the cell performances relative to planar bilayer architectures whereas cells with blends exhibited the highest efficiencies. Differences in cell performances with analogous layer architectures using two different polymers were attributed to the distinct charge mobility of the polymers. In view of the several benefits posed by the use of cross-linkable conjugated polymers in OPVs, ranging from higher morphologic stability to facilitated processing, our results provide insights for rational approaches when employing such materials.