Interface formation and electronic structure of α -sexithiophene on ZnO

Interface formation between the organic semiconductor α -sexithiophene (6T) and polar as well as nonpolar ZnO surfaces is investigated. The growth mode of the organic layer is strongly influenced by the orientation of the ZnO surface. No indication for chemisorption of 6T on ZnO is found by photoelectron spectroscopy. The energy level alignment at the 6T/ZnO interface is of type-II facilitating electron transfer from the organic to the inorganic part and hole transfer in the other direction, rendering this heterostructure interesting for photovoltaic applications.