ELECTRONIC-STRUCTURE OF POLYAROMATIC NITROGEN-COMPOUNDS - SURFACE ANALYTICAL AND ELECTROOPTICAL INVESTIGATIONS

The polymers of the aromatic nitrogen compounds N-methyl-pyrrole (P-N- Me-PPY), carbazole (PCarb), and aniline (PANI) have been investigated with electro-optical and surface analytical methods. The in-situ refle ction spectra indicate the formation of polarons or bipolarons during electrochemical oxidation, depending on polymer type. The absorption b ands can be attributed to changes in the electronic structure with reg ard to the applied potential. Photocurrent spectra of P-N-Me-PPY and P Carb show a p-type semiconducting behaviour for the polymers in the re duced state. The transition to the oxidized state with quasi-metallic properties is indicated by a significant shift in the Fermi level ener gy and can be followed with XPS and UPS measurements.