Organic photovoltaic's (OPVs) have been intensively investigated in recent years for generation of affordable, clean, and renewable energy due to their low-cost fabrication of large-area devices, light-weight, mechanical flexibility, and easy tunability of chemical properties of the polymer materials. The organic thin film solar cells prepared by PTB7/PC71BM composite were fabricated, characterized and their effects of additives were studied. Topographic images were obtained by the Atomic Force Microscopy (AFM). The current density-voltage (J-V) characteristics of photovoltaic cells were measured under the illumination of simulated solar light with 100 mW cm -2 (AM 1.5G) by an Oriel 1000 W solar simulator. The organic thin film solar cell fabricated with the 1:1.5 ratio shows the power conversion efficiency (PCE) of 3.92%. The obtained results show a considerable impact and bright future for organic polymer solar cells. © 2013 Elsevier B.V. All rights reserved.