Concentration-dependent effects of graphene quantum dots on the phase behavior and the electro-optical characteristics of the nematic liquid crystal 6CHBT

The concentration-dependent effects of graphene quantum dots (GQDs) on the phase behavior, optical, dielectric, conductivity, and the nematic liquid crystal 6CHBT's electro-optical characteristics have been systematically investigated. The incorporation of GQDs results in a reduction of the clearing temperature and alters the thermal hysteresis characteristics. FTIR analysis indicates that GQDs are dispersed within the 6CHBT matrix predominantly through physical interactions. Polarized optical microscopy reveals homogeneous dispersion at lower concentrations and localized GQD-rich domains at higher loading. Electro-optical investigations demonstrate significant modifications in rotating viscosity and the splay elastic constant, highlighting the interplay between homogeneous nanoparticle dispersion and aggregation. Differential scanning calorimetry revealed concentration-dependent changes in the nematic–isotropic transition. UV–visible spectroscopy showed band-gap variation from 4.18 eV to 4.05–4.10 eV with GQD loading. Dielectric studies revealed concentration-dependent changes in molecular dynamics and anisotropy, with low loading enhancing the response and higher loading causing aggregation and suppression.