A photoelectron emission study of polythiophene derivatives

Abstract

The difference between the energy of the top of the valence band in polythiophene and those in poly(3-alkylthiophene)s has been evaluated by photoelectron spectroscopy in air. The top of the valence band becomes higher in energy on gradually increasing alkyl chain length. This indicates that an acceptor dopant is relatively stable in poly(3-alkylthiophene)s with longer alkyl chain lengths, as observed. In doped polythiophene and poly(3-methylthiophene), the difference in the threshold energy of photoelectron emission is explained tentatively by electron emission from the polaron and bipolaron levels formed by the dopant.