Enhancement of the display parameters of 4′-pentyl-4-cyanobiphenyl due to the dispersion of functionalised gold nano particles

Abstract

We report electro-optical and dielectric studies of the gold nano particle (GNP) dispersed room-temperature liquid crystalline material 4′-pentyl-4-cyanobiphenyl (5CB) at a concentration of 0.1 wt%. Due to the dispersion of GNPs, the nematic to isotropic transition temperature is significantly increased. The threshold voltage required to switch molecules from the planar orientation (bright state) to the homeotropic (dark state) orientation is decreased. The dielectric parameters, namely, the longitudinal component of the dielectric permittivity and hence the dielectric anisotropy, are highly affected. The relaxation frequency corresponding to flip-flop motion of the 5CB molecules about their short axes has increased due to the presence of GNPs.

Keywords:

• nematic liquid crystal
• electro-optical properties
• gold nano particles
• display parameters
• transmission–voltage characteristic

Acknowledgements

The authors thank the Department of Science and Technology (DST), New Delhi for financial assistance under Project number SR/S2/CMP-12/2006. ASP thanks DST for a Senior Research fellowship under the project.