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

TL;DR

This paper introduces jumping kinetic Monte Carlo (jKMC), a fast and accurate simulation method for charge transport in organic semiconductors that accounts for partial delocalisation effects, significantly improving mobility predictions.

Contribution

The paper develops jKMC, a computationally efficient model that approximates delocalised kinetic Monte Carlo, enabling simulations of partial delocalisation regimes previously inaccessible.

Findings

Modest delocalisation can increase charge mobility by up to 100 times.

jKMC achieves accuracy comparable to dKMC with lower computational cost.

The method effectively models charge transport in disordered 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.