Effects of electron coupling to intra- and inter-molecular vibrational modes on the transport properties of single crystal organic semiconductors

TL;DR

This paper investigates how electron interactions with intra- and inter-molecular vibrational modes influence the transport properties of single crystal organic semiconductors, revealing complex temperature-dependent behaviors.

Contribution

It provides a non-perturbative model that accurately describes mobility and spectral properties considering both local and non-local vibrational couplings.

Findings

Mobility scales as T^{-δ} with δ > 1 at low temperatures

High-temperature behavior shows hopping with small activation energy

Model matches experimental order of magnitude for mobility

Abstract

Electron coupling to intra- and inter-molecular vibrational modes is investigated in models appropriate to single crystal organic semiconductors, such as oligoacenes. Focus is on spectral and transport properties of these systems beyond perturbative approaches. The interplay between different couplings strongly affects the temperature band renormalization that is the result of a subtle equilibrium between opposite tendencies: band narrowing due to interaction with local modes, band widening due to electron coupling to non local modes. The model provides an accurate description of the mobility as function of temperature: indeed, it has the correct order of magnitude, at low temperatures, it scales as a power-law $T^{-\delta}$ with the exponent $\delta$ larger than unity, and, at high temperatures, shows an hopping behavior with a small activation energy.