Symmetry Effects on Nonlocal Electron-Phonon Coupling in Organic Semiconductors

TL;DR

This paper presents a theoretical analysis showing that the symmetry of nonlocal electron-phonon interactions significantly influences the electronic properties and charge transport in organic semiconductors, highlighting the need to include both symmetric and antisymmetric couplings in models.

Contribution

It introduces a theoretical framework linking real-space electron-phonon coupling patterns to reciprocal space interactions, emphasizing the importance of symmetry considerations in transport models.

Findings

Symmetry of electron-phonon coupling affects electronic band dispersion.

Charge-carrier mobility depends on the symmetry of nonlocal interactions.

Models must include both symmetric and antisymmetric contributions.

Abstract

The electronic and electrical properties of crystalline organic semiconductors, such as the dispersions of the electronic bands and the dependence of charge-carrier mobility on temperature, are greatly impacted by the nonlocal electron-phonon interactions associated with intermolecular lattice vibrations. Here, we present a theoretical description that underlines that these properties vary differently as a function of the symmetry of the nonlocal electron-phonon coupling mechanism. The electron-phonon coupling patterns in real space are seen to have a direct and significant impact on the interactions in reciprocal space. Our findings demonstrate the importance of aspects that are usually missing in current transport models. Importantly, an adequate description of the electronic and charge-transport properties of organic semiconductors requires that the models take into account both antisymmetric and symmetric contributions to the nonlocal electron-phonon coupling mechanism.