Effect of Trans-Cis Isomerization of a Chiral Azo-Dye on Dye-Induced Ferroelectricity in an Achiral Liquid Crystal

A chiral azo-dye showing reversible trans-cis isomerization upon UV light irradiation was used as a dopant to induce ferroelectric properties in an achiral smectic C liquid crystal matrix. The kinetics of the isomerization in the smectic matrix was studied optically. The influence of the isomerization process on the ferroelectric properties of the mixture was investigated by observation of the ferroelectric switching in the smectic C phase and electroclinic response in the smectic A phase. The experimental results show that the banana-shaped cis isomers are less efficient in inducing the spontaneous polarization than their rodlike trans counterparts.