Influence of low concentration silver nanoparticles on the electrical and electro-optical parameters of nematic liquid crystals

Abstract

Thermodynamical, optical, dielectric and electro-optical characterisation of nematic liquid crystals (LCs) and silver nanoparticle (NP) composites have been carried out. Transition temperatures of pure and composites systems have been measured. Thermodynamical studies suggest increase of clearing temperature of the composite material as compared to the pure material. Threshold voltage for switching from bright to dark state and splay elastic constant of the pure and composite materials have been determined. From frequency dependence of dielectric measurements, permittivity, loss, relaxation frequency and dielectric strength of flip-flop mechanism of LC molecules in the nematic phase have been calculated. Dielectric properties of composites have been explained in reference of Maier and Meier theory. The effects of doping of NPs on dielectric and electro-optic properties of LC-NP composites have been discussed.

Keywords:

• liquid crystal nanoparticle composites
• display properties
• dielectric parameters
• transmission–voltage characteristics

Acknowledgements

The work is financially supported by DAE (BRNS) project No. 2010/20/37P/4/BRNS/1591. UBS thanks DAE (BRNS) for Junior Research Fellowship (JRF) under the project. We thank Dr Rohit Verma, Mr. Abhay S. Pandey and Mr. Avneesh Mishra for their help during experiments. We thank Dr. M. K. Chaturvedi, HoD Physics Department, and Dr. D. V. Sardesai, former Principal, VSSD College, Kanpur, for their support.