Ferroelectric nanoparticle/liquid-crystal colloids for display applications

A non-synthetic approach to modify liquid crystals (LCs) by dispersing low concentrations of ferroelectric nanoparticles is reported. These dilute colloids are stable and appear similar to a pure LC. However, by changing the concentration and the type of ferroelectric particles, the physical properties of the LC materials can be tailored, including the nematic isotropic transition temperature (T-NI), the dielectric constants, the birefringence (Delta n), elastic constants, and the threshold voltage. Specifically, doping low concentrations of BaTiO3 nanoparticles (similar to 1%) into a LC MLC-6609 increases T-NI up to similar to 40 degrees C. This giant shift of T-NI has never been previously reported and indicates strong interactions between the LC and ferroelectric nanoparticles on a molecular level. The doped LC also demonstrates significant enhancement in birefringence (by 10-30%), dielectric anisotropy (by similar to 50%), and the elastic constant K-33 (by similar to 20%). Ferroparticles act as molecular additives and modify the intrinsic properties of LC materials without time consuming and expensive chemical synthesis. The new LC materials are very attractive and suitable for use in displays, switchable lenses, beam steering, as well as other light-controlling devices.