Analysis of the sign-dependent switching observed in a hybrid aligned nematic cell
Cornford, Stephen Leslie
Taphouse, T. S.
Sambles, J. Roy
University of Exeter; HP Labs, Bristol
New Journal of Physics
Institute of Physics and Deutsche Physikalische Gesellschaft
An optical waveguide experiment was used to study the influence of dc electric fields on a hybrid aligned nematic liquid crystal cell. This dc switching differed from ac switching in two ways: first, the equilibrium states depended on the sign of the applied voltage, and second, there was transient activity over long (~100 ms) timescales. To understand both of these, a numerical model of the cell's dynamics, which included both the Ericksen–Leslie theory and a drift-diffusion model of mobile ions, has been developed. Comparing modelling with observations, we find that the transients are caused by the motion of tiny concentrations of ionic impurities, and that the sign dependence is caused by an asymmetric distribution of surface charge, rather than the flexoelectric effect.
Copyright © 2009 IOP Publishing Ltd and Deutsche Physikalische Gesellschaft. This is the published version of an article published in New Journal of Physics Vol. 11, article 013045. DOI: 10.1088/1367-2630/11/1/013045
11, article 013045