On the impact of nanoparticle doping on the electro-optic response of nematic hosts

Abstract

Functional composites of nanoparticles (NPs) dispersed in liquid crystals (LCs) have emerged into a topical research field of increasing interest over the last years. The promising combination of self-organising LC hosts with recent developments in nanotechnology offers great new opportunities for the use of LC materials in display applications and beyond. This article summarises our recent work on the effect of NP doping on the alignment and electro-optic performance of nematic hosts. An overview over the influence of size, shape and functionalisation of nanometre-sized particles on a nematic host is given and peculiarities compared to colloidal dopants are outlined. An extended electro-optical characterisation method for nematic nanocomposites is presented, which allows a distinction between NP-induced surface and bulk effects. Based thereon, new explanation models for NP-induced alignment and texture changes as well as the effect of NPs on the Fréedericksz-transition are elaborated and compared to previous studies. The dispersibility of particles is identified to be the key factor responsible for the impact of NP doping on the electro-optic response of the host. Based on these observations, a new strategy for the synthesis of functionalised particles is summarised that might lead to major improvements in the performance of LC display applications.