Improvement of interface formation between metal electrode and polymer film by polymer surface modification using ion sputtering

The surface of poly (9,9-dioctylfluorene) (PFO) film was modified by 1.0 keV Ar+ irradiation with a dose of 6.5×1014 ions/cm2 prior to Ca deposition. Ultraviolet and x-ray photoelectron spectroscopic studies indicated that the modified surface could effectively block Ca diffusion into the PFO film and prevent the formation of doping-induced bipolaron states in the former forbidden energy gap. As a result, a sharper metal contact on the surface of the PFO film could be formed, compared to that on the surface without Ar+ irradiation. The results suggest that the judicial surface modification of polymer surfaces may be useful for the improvement of metal/polymer contacts and thus device performance.