o-Quinodimethane-methano[60]fullerene and thieno-o-quinodimethane-methano[60]fullerene as efficient acceptor materials for polymer solar cells

Two novel 56π-electron fullerenes, o-quinodimethane-methano[60]fullerene (OQMF) and thieno-o-quinodimethane-methano[60]fullerene (TOQMF), were prepared by Diels–Alder reaction between methano[60]fullerene and o-quinodimethane type dienes. These fullerenes possess not only high LUMO levels but also sterically small addends, featuring outstanding performance in polymer solar cells. Up to 5.74% and 5.51% PCEs were achieved for OQMF/P3HT and TOQMF/P3HT solar cells, respectively.