We have investigated electrical properties of Al/PTF/PEDOT: PSS/ITO heterojunction structure at room temperature. Firstly, optical properties of the polymer [poly(pentachlorophenyl methacrylate)] were determined from ultraviolet-visible absorption spectra in the wavelength range of 200 to 700 nm. Optical band gap (E-g) of the polymer was found about 4.70 eV. Secondly, the PED-OT: PSS and polymer thin film (PTF) were prepared on the ITO substrate. The current transport mechanism and electrical parameters of Al/PTF/PEDOT: PSS/ITO heterojunction structure were investigated using current-voltage (IV) characteristics.