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Proceedings Paper

Electron-phonon coupling in binary organic semiconducting crystals (Conference Presentation)
Author(s): Rohan Isaac; Ajith Ashokan; Veaceslav Coropceanu; Laurie McNeil

Paper Abstract

Small-molecule based organic devices continue to demonstrate the highest mobilities of any organic materials, making them the evident choice for better performing organic devices. Here we study a range of binary charge-transfer crystals where a fraction of electronic charge is transferred from the donor molecule to the acceptor molecule. Due to significant electron-phonon coupling, the vibrational motion in these materials has a strong impact on the electronic characteristics. To quantify this polaronic effect, we have completed the measurements of resonance Raman and absorption spectra of the charge-transfer excitations and performed quantum-chemical calculations on a range of binary organic crystals with the same acceptor and a range of donor molecules. Comparison of the reorganization energies of intermolecular vs intramolecular phonons in these materials helps us understand the relative contribution of the two major electron-phonon coupling mechanisms: local vs non-local. We find that small variations in the donor molecule and thereby the resultant crystal structure can have a large impact on the predominant electron-phonon coupling mechanism. Understanding the reasons for these variations is important in selecting and designing materials with suitable characteristics for the next generation of electronic devices.

Paper Details

Date Published: 10 September 2019
Proc. SPIE 11097, Organic and Hybrid Field-Effect Transistors XVIII, 110970L (10 September 2019); doi: 10.1117/12.2529272
Show Author Affiliations
Rohan Isaac, The Univ. of North Carolina at Chapel Hill (United States)
Ajith Ashokan, Georgia Institute of Technology (United States)
Veaceslav Coropceanu, Georgia Institute of Technology (United States)
Laurie McNeil, The Univ. of North Carolina at Chapel Hill (United States)

Published in SPIE Proceedings Vol. 11097:
Organic and Hybrid Field-Effect Transistors XVIII
Iain McCulloch; Oana D. Jurchescu, Editor(s)

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