Interface dipole responsible for fermi level pinning in metal/3,4,9,10 perylenetetracarboxylic dianhydride interfaces

Current injection behavior in metal/3,4,9,10 perylenetetracarboxylic dianhydride (PTCDA) interfaces have been systematically studied. Observed interface behaviors show that the barrier of charge injection cannot be explained by simple vacuum level alignment scheme. Moreover injection barrier is found almost independent of metal work function. These observations are explained by the changes of barrier height due to interface dipole barrier which compensate for the difference of work function of PTCDA and metals leading to a metal independent injection barrier or Fermi level pinning at metal/PTCDA interfaces.