The external electric field effect on the charge transport performance of organic semiconductors: a theoretical investigation

Abstract

Efficiently controlling the charge transport properties of existing organic semiconductors to achieve a higher charge mobility is one of the hottest issues in the field of organic electronics. Compared with traditional chemical modification, the external electric field, as a non-chemical stimulation, is expected to regulate the charge transport properties flexibly and reversibly. However, the research on the electric field effect is far from sufficient, especially the inherent mechanism is still unclear. In this work, we theoretically investigated the response of electronic structures, molecular vibrational properties and the charge transport performance of three benzothiophene materials to the external electric field. After thorough first-principles and hybrid quantum and molecular mechanics (QM/MM) calculations, we found that the external electric field can bring momentous changes to the structures as well as charge transport properties of small-conjugated organic molecules with heteroatoms. In addition, breaking the anti-dipole stacking mode may achieve more drastic and directional regulation. Inspiringly, a new 1-azaanthracene crystal with a specific electric field response is designed, with a stupendous increase of mobility under −0.010 a.u. electric field. Our work systematically investigated the electric field effects on charge transport properties and revealed its working mechanism. We hope that the underlying structure–property relationships revealed in this work will contribute to providing a microscopic strategy to improve charge transport properties or design high-performance external electric field responsive molecules.