INTERACTION OF NA WITH SEXITHIOPHENE THIN-FILMS

The effects of Na on the electronic structure and electrical propertie s of alpha-sexithiophene (alpha 6T) are investigated with electron spe ctroscopic methods under UHV conditions. A shift of the valence-band e dge away from the Fermi level, and the evolution of states in the gap, can be determined. In a classical band-structure picture this could b e explained as an n-type doping process. However, all results point at a high localization of the negative charge at the sulfur atom which i s reflected in a very low specific conductivity.