Fullerene Bisadducts for Enhanced Open‐Circuit Voltages and Efficiencies in Polymer Solar Cells

A fullerene bisadduct can enhance the efficiency of polymer:fullerene bulk heterojunction solar cells. The bisadduct has a LUMO that is 100 meV higher compared to that of [6,6]-phenyl C61 butyric acid methyl ester (PCBM). This increases the open-circuit voltage of polymer:fullerene bulk heterojunction solar cells based on poly(3-hexylthio phene) and bisadduct PCBM to 0.73 V, while maintaining high fill factors and currents.