Barrier height formation for the PTCDA/Au(1Â 1Â 1) interface

► We use Density Functional calculations to analyze the PTCDA/Au(1 1 1) interface. ► Molecular charging energy effect on the transport gap has been also included. ► Alignment between the metal and organic levels is controlled by the charge transfer. ► IDIS model states the molecule CNL and the metal work function relative positioning. ► Good agreement with the experimental evidence is found.