A series of mono- and bisadducts of thieno-o-quinodimethane with C(60) (TOQC) was efficiently prepared through the Diels-Alder reaction of pristine or solubilizing side-chain-substituted 2,3-bis(chloromethyl)thiophene with C(60). The pristine TOQC bisadduct (bis-TOQC) shows much higher performance than the side-chain-substituted TOQC bisadducts in polymer solar cells, while the situation is inverse for the TOQC monoadducts. The best power conversion efficiency of 5.1% was achieved from the bis-TOQC:P3HT solar cells under simulated AM1.5G irradiation (86 mW/cm(2)).