Polyacetylene films were doped with FeCl₃ and implanted with 30 keV K⁺ ions. Physical changes to the films were examined by a series of measurements, which include the four-probe test, infrared ray absorption and 2 MeV He⁺ particle elastic recoil dettection and Rutherford backscattering. The chemical dopants (Fe⁺⁺⁺ and Cl^-) were redistributed after the implantation and the different species (K⁺, Fe⁺⁺⁺ and Cl^- ions) formed p-n junctions at the implantation depths. The implanted films exhibited desirable I - V characteristics, with current densities as high as 600 mA/cm^- at 3V and back - to - forward ratio of current over 300. The polymer diodes kept their behavior for over 60 days. Discussions on the results were given in detail.