Jumping kinetic Monte Carlo: Fast and accurate simulations of partially delocalised charge transport in organic semiconductors

Abstract

Developing devices using disordered organic semiconductors requires accurate and practical models of charge transport. In these materials, charge transport occurs through partially delocalised states in an intermediate regime between localised hopping and delocalised band conduction. Partial delocalisation can increase mobilities by orders of magnitude over conventional hopping, making it important for materials and device design. Although delocalisation, disorder, and polaron formation can be described using delocalised kinetic Monte Carlo (dKMC), it is a computationally expensive method. Here, we develop jumping kinetic Monte Carlo (jKMC), a model that approaches the accuracy of dKMC with a computational cost comparable to conventional hopping. jKMC achieves its computational performance by modelling conduction using identical spherical polarons, yielding a simple delocalisation correction to the Marcus hopping rate that allows polarons to jump over their nearest neighbours. jKMC can be used in regimes of partial delocalisation inaccessible to dKMC to show that modest delocalisation can increase mobilities by as much as two orders of magnitude.