Enhanced photocurrents were observed by employing zinc oxide doped single wall carbon nanotube (ZnO:SWCNT) in the photoactive medium of thin film organic solar cells (TFOSC). The investigations were conducted based on either poly 4,8-bis (2-ethyhexyl)oxy benzo(1,2-b:4,5-b’)dithiophene-2,6-diyl3-uoro-2-(2 ethylhexyl)carbonylthieno 3,4-bthiophenediyl (PTB7) blended with 6,6-phenyl-C61-butyric acid methyl ester (PCBM),PTB7:PCBM or poly (3hexylthiophene) (P3HT): 6,6-phenyl-C61-butyric acid methyl ester, P3HT:PCBM blend active layers containing ZnO:SWCNT nanocomposite at various concentrations. The best performances of the devices were found to be dependent on both the concentration of ZnO:CNT and the nature of the host medium. A substantial improvements in power conversion efficiencies (PCE) were observed as high as 68% and 31% for PTB7:PCBM and P3HT:PCBM blend with ZnO:CNT, respectively. Further device improvement were noted by employing co-solvent and solvent additive in the processing of TFOSC. The optical, electrical and morphological properties of photoactive films are discussed based on the experimental results along with the associated effect on device performances. •ZnO:CNT assisted charge transport improved the PCE of PTB7:PCBM organic solar cell by 68%.•The optimum ZnO:CNT loading in PTB7:PCBM blend was found to be 6% by weight.•Favourable phase segregations resulted in high photocurrent.•Charge mobility has increased by two order of magnitude by the use of solvent additives.