Schottky Barrier Height at Organic/Metal Junctions from First-Principles

We present a first-principles study of 3,4,9,10 perylenetetracarboxylic dianhydride (PTCDA) deposited on metal substrates (Al, Ag), focusing on the interaction between molecules and metal surfaces and on the fundamental mechanisms that control the alignment of molecular levels at the interface. The changes induced on the relevant electronic properties by the use of a different parametrization (i.e. Local density approximation vs. generalized gradient approximation) of the exchange-and-correlation potential within the density functional theory are discussed. The results show that the molecule-substrate interaction is rather weak and that the character of the contact is rectifying for all the metallic substrates.