Monte Carlo simulation based on dynamic disorder model in organic semiconductors: From bandlike to hopping transport

TL;DR

This paper uses Monte Carlo simulations incorporating a dynamic disorder model to explore how decoherence influences charge transport in organic semiconductors, revealing a transition from bandlike to hopping transport and estimating decoherence times in pentacene.

Contribution

It introduces a phenomenological decoherence parameter into the dynamic disorder model and demonstrates its critical role in transport transition and carrier localization in organic semiconductors.

Findings

Transport shifts from bandlike to hopping with shorter decoherence times

Decoherence time in pentacene estimated around 1 ps

Carrier localization increases as decoherence time decreases

Abstract

The dynamic disorder model for charge carrier transport in organic semiconductors has been extensively studied in recent years. Although it is successful on determining the value of bandlike mobility in the organic crystalline materials, the incoherent hopping, the typical transport characteristic in organic semiconductors, cannot be described. In this work, the decoherence process is taken into account via a phenomenological parameter, say decoherence time, and the projective and Monte Carlo method is applied for this model to determine the waiting time and thus the diffusion coefficient. We find the type of transport changes from bandlike to incoherent hopping with a sufficiently short decoherence time, which indicates the essential role of decoherence time in determining the type of transport in organics. We have also discussed the spatial extent of carriers for different decoherence time, and the transition from delocalization (carrier resides in about 10 molecules) to localization is observed. Based on the experimental results of spatial extent, we estimate the decoherence time in pentacene has the order of 1ps. Furthermore, the dependence of diffusion coefficient on decoherence time is also investigated, and corresponding experiments are discussed.