Influence of the electrode work function on the energy level alignment at organic-organic interfaces

The energy level alignment at interfaces, in stacks comprising of (4,4(')-N,N-'-dicarbazolyl-biphenyl) (CBP), (4,4,4(')-tris[3-methyl-phenyl(phenyl)amino]-triphenylamine) (m-MTDATA), and a conductive substrate, has been studied. We show that the alignment of energy levels depends on the equilibration of the chemical potential throughout the layer stack, while any electronic coupling between the individual layers is of lesser importance. This behavior is expected to occur for a broad class of weakly interacting interfaces and can have profound consequences for the design of organic electronic devices. (c) 2007 American Institute of Physics.