Semiconducting CdS quantum dots as a guest in a four ring bent-core nematic medium: modified dielectric and elastic properties

Abstract

The nematic phase of the bent-core family proves to be particularly fascinating due to its distinct properties in comparison to its calamitic counterpart. Here we revealed after the dispersion of semiconducting CdS QD an achiral unsymmetrical (4′-fluoro phenyl azo) phenyl-4-yl 3-[N-(4′-n-hecyloxy two hydroxybenzylidene)amino]-2-methylbenzoate (6-2M-F) a bent-core nematic (BCN) liquid-crystalline medium made of bent-shaped molecules with short cores and low bend angles. These molecules are on the cusp between conventional bent-core molecules and rod-like molecules, with characteristics somewhere in between, resembling hockey sticks. The threshold voltage (Formula presented.) dielectric permittivity (Formula presented.) and elastic constants (Formula presented.) of pure BCN have been considerably influenced by semiconductor nanoparticles. The threshold voltage (Formula presented.) of nano-disperse BCN has decreased with QD doping, and we know that the low operation voltage is one of the key considerations in the development of mobile liquid crystal display technology. Similar to other BCNs with smectic-like clusters previously described, the elastic anisotropy (Formula presented.) for 6-2M-F is negative; however, the insertion of CdS QDs causes the anisotropy to become very positive (bend elastic constant (Formula presented.) > splay elastic constant (Formula presented.)). While the parallel component of permittivity (Formula presented.) has declined with doping, the perpendicular component of permittivity (Formula presented.) has increased, leading to a considerable reduction in dielectric anisotropy (Formula presented.) in the nanocomposite, which implies the effect on nematic ordering due to the interaction between CdS QDs and the LC molecules.