Undoped and Doped Oligothiophenes: an In‐situ XPS‐, UPS‐, and HREELS‐Study

Abstract A new method for doping organic semiconductors is presented. The most common dopant for the widely used α‐sexithiophene (α6T), FeCl 3 , was co‐sublimed with the oligothiophene under UHV‐conditions. The solid‐state doping effects were studied for systematically varied dopant concentrations in‐situ with XPS. UPS, and HREELS. Up to a doping level of one effective charge per α6T the results can be interpreted as polaron formation. At higher dopant concentrations polaron bands are most probably formed.