Electrically driven structures in bent-core nematics

This review, dedicated to the memory of B. K. Sadashiva, concerns electrically driven patterns and defects in bent core nematics (BCNs) made of hard-core, soft-core or bent-rod type of molecules. It covers (a) spatially periodic patterns associated with electroconvection and flexoelectric deformation, (b) dislocations in these patterned states and (c) various types of defects induced essentially in homogeneous, unpatterned states of BCNs. While in general, the wealth of pattern morphologies is just as rich in BCNs as in rod-like nematics, certain features of electroconvection have so far been observed only in some BCN materials. Some attributes relating to the generation and behaviour of defects in electric field may also be ascribed to material properties specific to BCNs. It is also shown that the electric field–induced patterns as well as their modification by light irradiation may serve as optical gratings and thus establishes the background for designing new photonic devices.