The electron-accepting capability of fullerenes has made them interesting materials for organic photovoltaic cells (OPVCs). In this study, we propose the new methanofullerene derivatives incorporated with trimethylsilyl moiety to increase the solubility without electron transporting property decrease. Methanofullerene acceptor materials having trimethylsilyl substituent (PCB-Sis) were synthesized from the reaction of fullerene with trimethylsilyl substituted hydrazide type derivatives, electrochemical propertie was examined by cyclicvoltametry. OPVCs fabricated by using the mixture of P3HT and mono-adducts of PCB-Sis (Compound 7-9) as active layer showed 2.82% of power conversion efficiency under 100 mW/cm(2) AM1.5 simulated light after annealing at 150 degrees C for 10 min. Also, we have synthesized bis-adduct type PCB-Sis as moderate yield and obtained increased Voc about 0.5-0.14 V from P3HT and bis-adduct of PCB-Sis (Compound 10-12) based OPVCs. Unfortunately, these bis-adducts show slightly lower power conversion efficiency compare to mono-adducts due to the numerous region-isomers of bis-adducts. Although it was revealed our new PCB-Sis were candidates for acceptor materials in OPVCs.