Optical studies of n-octyloxy-cyanobiphenyl (8ocb) with dispersed ZnO nanoparticles for display device application

Liquid crystalline (LC) materials have the ability to transfer their long range orientation order in the dispersed materials such as nanoparticles and various colloids. ZnO nanoparticles have wide variety of applications and influence the birefringence properties of liquid crystalline molecules. The paper describes the systematic studies on liquid crystalline n-octyloxy-cyanobiphenyl (8ocb) compound with dispersed ZnO nanoparticles in different concentrations. The presence of ZnO nanoparticles in 8ocb are determined by optical, scanning electron microscopy (SEM) and X-ray diffraction (XRD) studies. The refractive indices and birefringence measurements are carried out at different wavelengths (460, 500, 570 and 635 nm) using wedge shaped cell with modified spectrometer. The birefringence (delta n) increases from 14 to 35% with increasing weight concentration of ZnO nanoparticles in the nematic thermal range. This is due to strong Vander Waal's interaction between LC molecules and ZnO nanoparticles which increases the alignment of the LC molecules. Further the order parameter S obtained from Kuczynski internal field model, Vuks model and Haller extrapolation methods are in good agreement. It is found that the order parameter S increases with increase in dispersion of concentration of ZnO nanoparticles from 11.2 to 23.9%. The prepared materials find potential applications in many optical devices.