The dependence of polarization and dielectric biaxiality on the enantiomeric excess in chiral dopant added to a smectic C host mixture

Abstract

The dielectric stabilization of the field-on states is an important feature for all SSFLC devices using the so-called C2 chevron geometry. This requires a combination of positive dielectric biaxiality and negative dielectric anisotropy. In the present work we use the phenylpyrimidine base mixture M192/62.5 as a non-chiral host and dope it by 10%of a chiral oxirane derivative with varying enantiomeric excess χ of the R-compound. The results confirm our basic expectations: while the polarization increases with increasing χ, the dielectric coefficients seem to be essentially independent on the enantiomeric excess, therefore on the spontaneous polarization. This result is remarkably different from our previous results on pure compounds showing a clear correlation between the dielectric biaxiality and spontaneous polarization in different molecular structures.

Key Words:

• Ferroelectric liquid crystals
• enantiomeric excess
• guest-host mixtures
• dielectric anisotropy
• dielectric biaxiality