Field-induced transition from homeotropic to planar geometry in the SmC* phase of an electroclinic liquid crystal

Abstract

The optical and electrical behavior was investigated of a symmetric liquid crystal (LC) cell: ITO–silane–LC–silane–ITO. The silane layer induces a perfect homeotropic alignment of the molecules of the studied electroclinic liquid crystal (ELC) material, BDH 764E. A field-induced transition from the perfect homeotropic to planar orientation in the chiral smectic C (SmC*) and smectic A (SmA) phases of the ELC was observed. Optical and dielectric studies were performed for both alignment (geometry) modes. The field-induced transition from the homeotropic to planar orientation was studied vis-à-vis the high negative dielectric anisotropy obtained in the studied material. Such an ELC with large negative dielectric anisotropy and perfect homeotropic alignment may have important implications for modern LC display technology.

Keywords:

• liquid crystal
• homeotropic phase
• silane layer
• dielectric anisotropy

Acknowledgements

The authors sincerely thank Dr Vikram Kumar, Director, National Physical Laboratory, for continuous encouragement and interest in this work. We sincerely thank Dr Puja Goel, Mr Jai Prakash and Mr Ajay Kumar for fruitful discussions. Authors are thankful to the Department of Science and Technology (DST), New Delhi for supporting this work under the project No. SR/S2/CMP-03/2005. The authors (AM, IC and AC) are thankful to CSIR, New Delhi for financial assistance.