Modeling of charge transport across disordered organic heterojunctions

Abstract

Organic electronic devices often consist of a sandwich structure containing several layers of disordered organic semiconductors. In the modeling of such devices it is essential that the charge transport across the organic heterojunctions is properly described. The presence of energetic disorder and of strong gradients in both the charge density and the electric field at the heterojunction complicates the use of continuum drift–diffusion approaches to calculate the electrical current, because of the discrete positions of the sites involved in the hopping transport of charges. We use the results of three-dimensional Monte Carlo simulations to construct boundary conditions in a one-dimensional continuum drift–diffusion approach that accurately describe the charge transport across the junction. The important effects of both short- and long-range Coulomb interactions at the junction are fully accounted for. The developed approach is expected to have a general validity.