Abstract

Low charge mobilities in molecular electronic materials limit the charge collection efficiency of organic solar cells and inhibit the performance of organic light emitting devices, solar cells, thin-film transistors and other devices. The slow transport arises from the weak intermolecular electronic coupling and the inherent disorder in conjugated molecular films, and is strongly influenced by the morphology, composition and chemical structure of the materials. However, the relationship between the chemical and physical structure of the material and the charge transport properties is complex and is not well understood. The combination of Monte Carlo (MC) methods for the simulation of hopping in disordered systems together with quantum chemical (QC) techniques for the computation of electron transfer rates and molecular dynamics (MD) for the simulation of molecular conformation provides a powerful tool for investigation of this relationship. In this talk, we will present simulation studies of charge transport for disordered organic crystals, discotic liquid crystals, and conjugated polymers, all based on this combination of techniques. We focus on the influence of parameters such as side-chain structure and length, and the relative effects of configurational and energetic disorder. In each case we show how experimentally observed transport behaviour can be explained at least qualitatively by the simulations.