Chasing the ‘killer’ phonon mode for the rational design of low disorder, high mobility molecular semiconductors

Schweicher, G., D'Avino, G., Ruggiero, M. T., Harkin, D. J., Broch, K., Venkateshvaran, D., Liu, G., Richard, A., Ruzié, C., Armstrong, J., Kennedy, A. R., Shankland, K. ORCID: https://orcid.org/0000-0001-6566-0155, Takimiya, K., Geerts, Y. H., Zeitler, J. A., Fratini, S. and Sirringhaus, H. (2019) Chasing the ‘killer’ phonon mode for the rational design of low disorder, high mobility molecular semiconductors. Advanced Materials, 31 (43). 1902407. ISSN 0935-9648 doi: 10.1002/adma.201902407

Abstract/Summary

Molecular vibrations play a critical role in the charge transport properties of weakly van der Waals bonded organic semiconductors. To understand which specific phonon modes contribute most strongly to the electron – phonon coupling and ensuing thermal energetic disorder in some of the most widely studied high mobility molecular semiconductors, we have combined state-of-the-art quantum mechanical simulations of the vibrational modes and the ensuing electron phonon coupling constants with experimental measurements of the low-frequency vibrations using inelastic neutron scattering and terahertz time-domain spectroscopy. In this way we have been able to identify the long-axis sliding motion as a ‘killer’ phonon mode, which in some molecules contributes more than 80% to the total thermal disorder. Based on this insight, we propose a way to rationalize mobility trends between different materials and derive important molecular design guidelines for new high mobility molecular semiconductors.

Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/85316
Item Type	Article
Refereed	Yes
Divisions	Interdisciplinary centres and themes > Chemical Analysis Facility (CAF) > Xray (CAF) Life Sciences > School of Chemistry, Food and Pharmacy > School of Pharmacy > Pharmaceutics Research Group
Publisher	Wiley
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