A one dimensional variable range hopping type conduction is observed in Poly (3, 4-ethylenedioxythiophene): polystyrenesulfonate (PEDOT:PSS) films obtained by a spin coating technique on polyethylene naphthalate (PEN) substrate and the mechanism behind enhancement in conductivity in 3 % dimethyle sulfoxide (DMSO) doped PEDOT:PSS film is due to the phase segregation of PSS on the surface and reduction of energy barrier between the conducting grains. Enhanced conductivity of PEDOT:PSS films and transparency more than 80 % in the visible region makes PEDOT:PSS films suitable for flexible and transparent optoelectronic devices.