MOSSBAUER STUDY OF FECL3-DOPED POLYTHIOPHENE AND POLY(3-OCTYLTHIOPHENE)

We have specified the chemical species of the dopants in FeCl3-doped p olythiophene and poly(3-octylthiophene) through Fe-57-Mossbauer study as FeCl4- with slightly distorted tetrahedral structure. Spectra with a quadrupole-split doublet were observed for polythiophene, while thos e for poly(3-octylthiophene) were broadened by magnetic relaxation. Ap plication of a magnetic field induced magnetically split spectra in bo th polymers due to a suppression of the relaxation frequency. In these conducting polymers there exist two kinds of chemical species with di fferent relaxation frequency. The relaxation in poly(3-octylthiophene) is considerably slower than in polythiophene. The relaxation mechanis m is attributable to the interaction between dopant spins and carrier spins.