Home > Research > Publications & Outputs > Second-harmonic generation and the influence of...

Associated organisational unit

Links

Text available via DOI:

View graph of relations

Second-harmonic generation and the influence of flexoelectricity in the nematic phases of bent-core oxadiazoles

Research output: Contribution to journalJournal article

Published
  • J. Addis
  • S. Kaur
  • D. J. Binks
  • M. R. Dickinson
  • C. Greco
  • A. Ferrarini
  • Verena Beatrice Gortz
  • John W. Goodby
  • Helen F. Gleeson
Close
<mark>Journal publication date</mark>10/2016
<mark>Journal</mark>Liquid Crystals
Issue number10
Volume43
Number of pages18
Pages (from-to)1315-1332
Publication statusPublished
Early online date24/04/16
Original languageEnglish

Abstract

Second-harmonic generation (SHG) in the nematic phase of bent-core oxadiazole-based liquid crystals (LCs) was studied and compared to that for the rod-like compound 4-cyano-4ʹ-n-octylbiphenyl (8CB). Weak, isotropically scattered second-harmonic (SH) light was observed for all materials, consistent with SHG by nematic director fluctuations. The SH intensity produced by the bent-core materials was found to be up to ~ 3.4 times that of 8CB. We discuss this result in terms of the dependence of SH intensity on temperature, elastic constants and flexoelectric coefficients. We have calculated the latter by using a molecular field approach with atomistic modelling, thus demonstrating how molecular parameters contribute to the flexoelectric coefficients and illustrating the potential of this method for predicting the flexoelectric behaviour of bent-core LCs. We show that the increased SH signal in the bent-core compounds is partly due to their nematic phases being at a much higher temperature, and also potentially due to them having greater flexoelectric coefficients, up to ~1.5 times those of 8CB. These estimates are consistent with reports of increased flexoelectric coefficients in bent-core compounds in comparison to rod-like compounds.