Here, we report the fabrication of high efficiency poly(3-hexylthiophene) (P3HT) and [ 6,6]-phenyl C61-butyric acid methyl ester (PCBM) and [6,6]-diphenyl-C(62)-bis(butyric acid methyl ester) (bis-PCBM) blended photovoltaic cells. Bulk hetero-junction photovoltaic cells with an ITO/G-PH/P3HT: PCBM (or bis-PCBM)/TiO(x)/Al configuration were fabricated, and the device using P3HT: bis-PCBM (1: 0.7) showed the best performance compared with those using P3HT: PCBM (1: 0.7). A maximum power conversion efficiency (PCE) of 4.50% (V(oc) = 0.64 V, FF = 0.62) was achieved with P3HT: bis-PCBM (1: 0.7).