Surface anchoring effect on guest–host ferroelectric liquid crystal response time – an electro-optical investigation

Abstract

The effect is reported of surface anchoring on various electro-optical parameters of a pure ferroelectric liquid crystal (FLC) and five mixtures with different concentrations of dye. The Anthraquinone D5 dye was used as guest entity, whereas Felix 17-000 was used as host in this investigation. The presence of dye molecules in the FLC dramatically affects the electro-optical properties compared with those of the pure system. Electro-optical parameters such as spontaneous polarization and rotational viscosity not only change with the addition of dye but they are also strongly dependent on the concentration of dye in pure FLC. The effect of dye molecules on the anchoring energy of the pure FLC system was also investigated. Due to strong anchoring energy on FLC substrate, its effect on response time was also studied. An improvement in the contrast ratio after dye doping was observed. The value of spontaneous polarization increases due to addition of dye, suggesting that molecular alignment improves, which is very useful from the application point of view.

Keywords:

• ferroelectric liquid crystal
• surface anchoring energy effect
• optical response time

Acknowledgements

One of the authors (A.K.M.) is thankful to UGC, New Delhi for the grant of SRF. The authors are sincerely thankful to DST, New Delhi for the financial assistance in the form of project for the present work. The authors are also thankful to UGC, New Delhi for providing financial assistance in the form of SAP.