Aiming at improving the phase behavior of the OPVCs, we have designed and synthesized a series of C60 and C70 derivatives, which showed high electron mobility, electron affinity, and good solubility. These methanofullerene acceptor materials having ethyleneoxy substituent, PCBEs, were synthesized from the reaction of fullerene C60 or C70 with each hydrizide. Device performances of OPVC using the mixture of P3HT and PCBEs as an active layer were measured under illumination of 100 mW/cm2 AM 1.5G simulated light. Pristine OPVC using P3HT:compound 3 showed 2.59% of power conversion efficiency, which is much higher than 1.65% of pristine P3HT:PCBM device. The electrochemical and photophysical properties of these methanofullerene derivatives were examined by using cyclicvoltammetry and UV-Vis spectroscopy, respectively. We revealed that ethyleneoxy substituted methanofullerenes can be used as a good candidate for acceptor materials in OPVCs.