Comparison of Heterogeneously and Homogeneously Doped Polyphenylacetylene Using IR and XPS

Infrared (IR) and x-ray photoemission spectroscopy (XPS) studies have been made on heterogeneously iodine-doped polyphenylacetylene (PPA) polymer films. Similarities and differences between the doping processes (heterogeneous and homogeneous) are presented. Results point to a surface doping process in the heterogeneously doped films vs. a bulk process in the homogeneously doped materials (doped in solution). The counter anion moiety in the films appears to be the polyiodide I 5 − ion, as contrasted to the bulk powder (homogeneously doped) polymer in which the species of I 2 , I 3 − in the presence of a predominance of I 5 − ion coexist.