Electronic States in Polythiophene and Poly(3-methylthiophene) Studied by Photoelectron Spectroscopy in Air

Abstract

The difference of the energy of the top of the valence band in polythiophene and poly(3-methylthiophene) has been evaluated by photoelectron spectroscopy in air to be about 0.2 eV in coincidence with that obtained by cyclic voltammetry in electrolytes. In the doped state of poly(3-methylthiophene) with BF 4 - , the threshold energy of the photoemission has been found to decrease by about 0.4 eV compared with the undoped sample. This is discussed in terms of polaron state formation by doping.