EFFECT OF TRANS-CIS ISOMERIZATION OF A CHIRAL AZO-DYE ON DYE-INDUCED FERROELECTRICITY IN AN ACHIRAL LIQUID-CRYSTAL

A chiral ate-dye showing reversible trans-cis isomerization upon UV li ght irradiation was used as a dopant to induce ferroelectric propertie s in an achiral smectic C liquid crystal matrix. The kinetics of the i somerization in the smectic matrix was studied optically. The influenc e 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 ph ase. The experimental results show that the banana-shaped cis isomers are less efficient in inducing the spontaneous polarization than their rodlike trans counterparts.