Chasing the "Killer" Phonon Mode for the Rational Design of Low‐Disorder, High‐Mobility Molecular Semiconductors. Issue 43 (12th September 2019)

• Record Type: Journal Article
• Authors: Schweicher, Guillaume; D'Avino, Gabriele; Ruggiero, Michael T.; Harkin, David J.; Broch, Katharina; Venkateshvaran, Deepak; Liu, Guoming; Richard, Audrey; Ruzié, Christian; Armstrong, Jeff; Kennedy, Alan R.; Shankland, Kenneth; Takimiya, Kazuo; Geerts, Yves H.; Zeitler, J. Axel; Fratini, Simone; Sirringhaus, Henning
• Is Part Of: Advanced materials. Volume 31:Issue 43(2019)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2019-09-12
• Subjects: charge transport -- dynamic disorder -- field‐effect transistors -- molecular design -- organic electronics -- transient localization scenario; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adma.201902407
• Languages: English
• ISSNs: 0935-9648

Abstract

Abstract: 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, state‐of‐the‐art quantum mechanical simulations of the vibrational modes and the ensuing electron–phonon coupling constants are combined with experimental measurements of the low‐frequency vibrations using inelastic neutron scattering and terahertz time‐domain spectroscopy. In this way, the long‐axis sliding motion is identified as a "killer" phonon mode, which in some molecules contributes more than 80% to the total thermal disorder. Based on this insight, a way to rationalize mobility trends between different materials and derive important molecular design guidelines for new high‐mobility molecular semiconductors is suggested. Abstract : Molecular vibrations strongly impact the charge transport properties of weakly van der Waals bonded organic semiconductors. Quantum mechanical simulations, combined with low‐frequency vibrational spectroscopy, enable resolution of vibrational modes and ensuing electron–phonon coupling constants. The long‐axis sliding motion of molecular subunits is identified as a "killer" phonon mode, which in some materials contributes more than 80% to the total thermal disorder.