Electronic structure of thin films of hydrocarbon molecules under an external electric field

Abstract

Using the density functional theory combined with the effective screening medium method, we studied the electronic structures of thin films of naphthalene under the external electric field in terms of their molecular conformation with respect to the electrode. Our calculations showed that the carrier accumulations and depletions strongly depend on the molecular conformation to the electrode. Carriers are primarily distributed on the molecules situated near the electrode. Furthermore, asymmetric carrier accumulation with respect to the carrier species occurs for the thin films where the molecules have tilting arrangements to the electrode. For the slabs consisting of six molecular layers, injected carriers are distributed throughout the slab irrespective of the carrier species. On the other hand, the carrier penetration is highly suppressed for the slabs where the molecules possess tilting conformation with respect to the electrode.