Chloroform, Chlorobenzene, 1, 2-Dichlorobenze and co-solvent Chlorobenzene with Chloroform (1:1) were used to investigate the influence of the solvent on the morphology of P3HT:PCBM (with the ratio 1:1) as well as the photovoltaic properties of organic solar cells based on this polymer blend. Using co-solvents leads to higher absorption intensity as compared to other studied solvents. XRD measurements reveal improved crystallinity in P3HT films prepared by chloroform and chlorobenzene while large aggregates appeared in films prepared using dichlorobenzene. Films produced using co-solvents show well-ordered structure and improved crystallinity; these results were further confirmed by SEM images. The J(V) measurements show that a maximum PCE of 1.47% is obtained in films produced using co-solvents. This was associated with significant improvement in current density (11.77mA/cm2) and a fill factor of 0.4 which was determined from the series and shunt resistances. Open circuit voltage has decreased in film prepared by co-solvents (0.31 Volt), and improved significantly (0.54 Volt) in film prepared in chloroform