Electron-phonon coupling and mobility modeling in organic semiconductors: method and application to tetracene polymorphs

TL;DR

This paper introduces a first-principles method to calculate electron-phonon coupling and temperature-dependent charge mobilities in organic semiconductors, validated on tetracene polymorphs with good experimental agreement.

Contribution

The paper presents a novel computational approach for electron-phonon coupling and mobility modeling in organic semiconductors, specifically applied to tetracene polymorphs.

Findings

Calculated Raman spectra match experimental data.

Computed mobilities agree with experimental values within error margins.

Differences between polymorphs are analyzed and discussed.

Abstract

We have developed a first-principles method to calculate the electron-phonon coupling for specific modes and q-points in the Brillouin Zone for crystalline organic semiconductors. Using the obtained coupling strengths, we propose an approach to compute the temperature-dependent mobilities of electrons and holes. This methodology is applied to both bulk and thin-film polymorphs of tetracene. To validate our treatment of the electronic structures and vibrational properties, we calculate the Raman spectra in the lattice-phonon region and compare them with experimental data. We then compare the computed mobilities with available data for single crystals, finding good agreement within the experimental range, especially when accounting for possible charged impurities. Finally, we discuss the observed differences between the polymorphs.