Simple charge transport model for efficient search of high-mobility organic semiconductor crystals

Abstract

Search for materials with high charge mobilities among the plethora of synthesizable organic semiconductors is of paramount importance for organic electronics, and virtual screening is expected to guide and streamline this process. However, a model for rapid but reliable prediction of charge mobility in organic semiconductors is still lacking. To address this challenge, a simple “diffusion-of-delocalized-polaron” model is suggested in this study. It considers the most essential factors governing the charge transport: intermolecular electronic coupling, electron-phonon interaction, charge delocalization, static and dynamic disorder. The suggested model reproduces experimental charge mobilities in various organic semiconductors remarkably well, and significantly outperforms another approach previously used for screening of organic semiconductors – the Marcus model. Moreover, charge mobility values predicted by our model are closer to the experiment than those provided by the two state-of-the-art approaches – quantum nuclear tunneling model and second-order cumulant expansion of the density matrix – and are on par with the popular transient localization theory. It is thus anticipated that the suggested model is an efficient tool for the search of high-mobility materials, revealing of structure-mobility relationships and rational design of organic semiconductors. Its possible integration with crystal structure prediction can boost the development of organic electronics.