Effect of inorganic 1D nanoparticles on electrooptic properties of 5CB liquid crystal

Electrooptic properties of mixtures of 4-cyano-4'-pentylbiphenyl (5CB) thermotropic liquid crystal with four different inorganic dopants: (i) MoSI nanowires, (ii) MnO2 nanorods, (iii) Ag nanowires, and (iv) WS2 nanotubes were investigated by a conventional optical measurement technique. The dopant concentrations were in the range from 0.1 to 0.5 wt%. In all mixtures aggregation of the 1D nanoparticle (1D-NP) material was observed, therefore electrooptic response was probed in the regions in-between the aggregates. All four 1D-NP dopants produce a decrease of the threshold voltage for electrooptic switching and also a decrease of the corresponding switching times. The most profound effects are observed for MnO2/5CB system, which exhibits a reduction of the threshold voltage by a factor of 1.7 and a reduction of the total switching time by a factor of 1.5. The effect is associated with an increase of the dielectric anisotropy of the mixture. The specific behaviour of the MnO2 nanorods is attributed to their relatively low aspect ratio that provides most suitable conditions for good alignment in the liquid crystal host. (C) 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim