Finite-Size Scaling of Charge Carrier Mobility in Disordered Organic Semiconductors

TL;DR

This paper introduces a method to accurately estimate macroscopic charge carrier mobility in disordered organic semiconductors from finite-size simulations, validated against previous approaches and applicable to various models.

Contribution

A simple, validated extrapolation method for charge mobility from microscopic system sizes to macroscopic scales in disordered semiconductors.

Findings

The proposed method effectively extrapolates mobility from finite-size data.

Analytic estimates for system sizes needed in simulations are provided.

Method is applicable beyond lattice models and specific rate expressions.

Abstract

Simulations of charge transport in amorphous semiconductors are often performed in microscopically sized systems. As a result, charge carrier mobilities become system-size dependent. We propose a simple method for extrapolating a macroscopic, nondispersive mobility from the system-size dependence of a microscopic one. The method is validated against a temperature-based extrapolation [Phys. Rev. B 82, 193202 (2010)]. In addition, we provide an analytic estimate of system sizes required to perform nondispersive charge transport simulations in systems with finite charge carrier density, derived from a truncated Gaussian distribution. This estimate is not limited to lattice models or specific rate expressions.