Molecular fingerprints in the electronic properties of crystalline organic semiconductors: from experiment to theory

TL;DR

This paper demonstrates that combining photoemission spectroscopy with advanced theoretical models accurately captures the electronic properties of pentacene crystals, emphasizing the importance of vibrational coupling and disorder in organic semiconductors.

Contribution

It introduces a non-perturbative dynamical mean field theory extension to ab initio calculations that aligns well with experimental photoemission data for organic semiconductors.

Findings

Excellent agreement between theory and experiment for bandwidth, dispersion, and lifetime.

Properly accounting for vibrational modes and disorder is crucial.

Traditional band structure theories are insufficient for these materials.

Abstract

By comparing photoemission spectroscopy with a non-perturbative dynamical mean field theory extension to many-body ab initio calculations, we show in the prominent case of pentacene crystals that an excellent agreement with experiment for the bandwidth, dispersion and lifetime of the hole carrier bands can be achieved in organic semiconductors provided that one properly accounts for the coupling to molecular vibrational modes and the presence of disorder. Our findings rationalize the growing experimental evidence that even the best band structure theories based on a many-body treatment of electronic interactions cannot reproduce the experimental photoemission data in this important class of materials.