Assembly and electronic structure of octithiophene on Au(1 1 1)

Scanning tunneling microscopy and spectroscopy as well as photoemission spectroscopy have been employed to study the adsorption behavior and electronic structure of α-octithiophene (8T) on Au(1 1 1). At a monolayer (ML) and bilayer coverage well-ordered molecular rows forming closely packed films are found, with 8T molecules tilted with respect to the surface plane allowing for intermolecular π–π-interactions. Two unoccupied electronic states are observed, which possess the same energetic position for 1 and 2 ML, indicating a low electronic coupling strength between 8T and the metallic substrate. This study shows that 8T grow on Au(1 1 1) in an ordered way generating a defined interface which is a basic requirement for future applications of 8T in (opto) electronic devices.