Multiscale study of charge mobility of organic semiconductor with dynamic disorders

Abstract

The impact of dynamic disorder arising from the thermal fluctuations on the charge transport in organic semiconductors is studied by a multi-scale approach combining molecular dynamics, electronic structure calculations and kinetic Monte Carlo simulations for pentacene crystal of thin-film phase. It is found that for 1-D arrays, such fluctuations severely reduce charge mobility as temperature increases. However, when going from an 1-D array to an 2-D herringbone layer, for a wide range of temperatures, the charge transport property is found to be unaffected by such disorders from our multiscale computational study. And in some extreme cases, when the fluctuations of the hopping integral are even larger than their average values, the dynamic disorders can increase the charge mobility. In addition, we point out that the “band-like” behavior concluded by the experiment can be reproduced by quantum charge transfer involving nuclear vibration tunneling effects within a hopping model.