Band alignment in organic materials

Abstract

Band alignment at metal/organic (MO) and organic/organic (OO) interfaces is discussed within a unified Induced Density of Interface States (IDIS) model, which incorporates most of the effects that can be expected to operate at weakly interacting organic interfaces: compression of the metal electron tails due to Pauli repulsion, orientation of molecular dipoles and electron charge transfer between the two media. This last mechanism tends to align the Charge Neutrality Level (CNL) of the organic material and the metal Fermi level (EF): electron charge transfer reduces the initial misalignment between the CNL and the metal work function (φM-CNL) to S(φMM - CNL), where S is the interface screening parameter which is shown to also screen the 'Pauli' and molecular interface dipoles. Results for several Au/organic and organic/organic interfaces are presented and discussed. © 2009 Springer-Verlag Berlin Heidelberg.