Electronic Charge Transport in Extended Nematic Liquid Crystals

Woon, K.L. and Aldred, M.P. and Vlachos, P. and Mehl, G.H. and Stirner, T. and Kelly, S.M. and O'Neill, M. (2006) Electronic Charge Transport in Extended Nematic Liquid Crystals. Chemistry of Materials, 18 (9). pp. 2311-2317. ISSN 0897-4756, DOI https://doi.org/10.1021/cm0601335.

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Official URL: http://pubs.acs.org/doi/abs/10.1021/cm0601335


We report a systematic study of charge transport in a range of low-molar-mass and extended (having at least six aromatic rings) nematic liquid crystals, some of which are reactive mesogens, with a high degree of shape anisotropy, i.e., the length-to-width (aspect) ratio is exceptionally high. We demonstrate that the hole mobility is independent of the macroscopic, but not microscopic, ordering of the nematic and isotropic phases of these nematic liquid crystals with a long, rigid, and extended aromatic molecular core, because no discontinuity is observed at the transition between these phases. A room-temperature mobility of up to 1.0 × 10-3 cm2 V-1 s-1 is obtained in the nematic phase, which is attributed to the short intermolecular distances between the highly polarizable but rigid long aromatic cores. We show that the intermolecular separation can be easily fine-tuned by changing the lateral and terminal aliphatic groups of these nematic liquid crystals. Hence, the charge mobility can be varied by up to 2 orders of magnitude without altering the core structure of the molecules, and this chemical fine control could be used to limit hole transport and so provide better charge balance in organic light-emitting diodes. X-ray diffraction is used to obtain the intermolecular separation and shows local lamellar order in the nematic phase.

Item Type: Article
Uncontrolled Keywords: Electronic Charge Transport; Extended Nematic Liquid Crystals
Subjects: Q Science > Q Science (General)
Q Science > QC Physics
Divisions: Faculty of Science > Department of Physics
Depositing User: Ms. Juhaida Abd Rahim
Date Deposited: 27 Feb 2015 05:18
Last Modified: 27 Feb 2015 05:18
URI: http://eprints.um.edu.my/id/eprint/12899

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