Electronic states of conducting polymeric liquid states studied by photoelectron emission in air

Electronic energy states of various fusible conducting polymers in the liquid state were studied by atmospheric UV photoemission spectroscopy. The energy of the conduction band top or HOMO of poly(3-alkylthiophene)s (PATs) shows anomalous temperature dependence. That is, PATs with alkyl side chain length shorter than hexadecyl (C/sub 16/H/sub 33/) show a higher photoemission threshold energy in the liquid state than those in the solid state, while the PATs with longer side chain length show the opposite behavior, although the main chain structure and thus the /spl pi/-electron system of these polymers are thought to be almost the same. The electronic energy states of other conducting polymers whose main chain structure differs from PAT as well as anomalous features observed in the optical and electronic properties such as photoluminescence and photoconductivity of the conducting polymers in the liquid state were also discussed.