New Photoactive Guest-Host Nematics Showing Photoflexoelectricity

Abstract

Here we present new results on guest-host nematic systems featuring an optical degree of freedom based on the trans-cis photoizomerization of a single azo-bond or two azo-bonds in guest mesogens, with or without a longitudinal dipole moment. Homeotropic nematic layers in horizontal electric fields, subjected to illumination by UV or white light, were investigated. A marked, reversible UV increase of the flexoelectrooptic effect was found in case of guest molecules with a longitudinal dipole moment.

Keywords:

• Azo-bond isomerization
• electrooptic effect
• photoflexoelectricity
• surface vs. bulk contribution

Acknowledgment

This study is carried out under the Indo-Bulgarian joint research project (No. INT/BUL/B-75/07) supported by the Department of Science and Technology, New Delhi and the Ministry of Education and Science, Scientific Studies Fund of Bulgaria.