Ferroelectric liquid crystals: futuristic mesogens for photonic applications

The past 10 years of molecular ferroelectrics: structures, design, and properties

“…24b). 285 Ferroelectric liquid crystals, as a specific type of liquid crystal material, exhibit both liquid crystalline and ferroelectric properties. In 1973, Meyer articulated a comprehensive set of symmetry arguments supporting the concept that a chiral smectic C phase (S C *) should exhibit ferroelectric properties, and in 1975, presented experimental evidence confirming the existence of ferroelectric liquid crystals.…”

“…Consequently, this rotation causes the direction of polarization to change, resulting in a helical superstructure and macroscopic polarization with typical value of BnC cm À2 . 285 Recently, the identification of polar nematic phases, comprised of a ferroelectric nematic (N F ) phase (Fig. 24d), ferroelectric chiral nematic (N F *) phase, and antiferroelectric splay nematic (N S ) phase, has injected renewed vigor into the field of ferroelectric liquid crystals.…”

Lateral electric field switching in thin ferroelectric nematic liquid crystal cells

“…Liquid crystals (LCs) have been used in many kinds of electrooptic applications, including displays, lenses, waveguides, switches, and beam steerers. [1][2][3][4][5] Almost all applications are based on the nematic LC phase, in which long-shaped organic molecules are mainly oriented parallel to each other, but otherwise free to flow in 3 dimensions. The individual molecules have typically a permanent dipole moment, but the nematic phase has inversion symmetry and therefore no net polarization.…”

“…This kind of dielectric interaction leads to switching that requires typically tens of milliseconds, which is too slow for many applications. 5 Thankfully, in some special nematic phases, the molecular dipoles tend to orient in the same direction, which leads to a permanent polarization in a certain temperature range. [6][7][8][9][10][11] Such a material is called a ferroelectric nematic phase liquid crystal (N f phase).…”

“…This kind of dielectric interaction leads to switching that requires typically tens of milliseconds, which is too slow for many applications. 5…”