Initial stage of adsorption of octithiophene molecules on Cu(111)

► A characteristic molecular chain structure of 8T molecules on a Cu(111) is found. ► The molecular orientation of 8T is found to be dependent on the coverage of 8T. ► 8T molecules in the molecular chain align along the Cu<11-2> direction. ► With increasing coverage, 8T molecules aligning along the Cu<110> direction appear. ► Fragments of 8T, such as single thiophene molecules, are also observed.