Dielectric and electro-optic behaviour of nematic-SWCNT nanocomposites under applied bias field

Composite of DNA-Stabilized Multiwalled Carbon Nanotube and Nematic Liquid Crystal for Display Performance Optimization

“…On one hand, MWCNTs with porous structures can serve as traps for the undesired impurity ions in 5CB, which may permit the thinness of the electric double layer and, in turn, allow the nematic molecules in the doped cell to experience a relatively higher effective external field under the same applied voltage and thus lead to the lowering of the threshold voltage, as analyzed in the earlier literature. , On the other hand, MWCNTs with large aspect ratio and induced dipole moment will induce the parallel orientation of them to the LC director, which may increase the dielectric anisotropy of MWCNT/5CB composites and further help reduce the threshold voltage. This is also consistent with the reports in the literature. , However, the U th decreased only by 1.04% for the composite of 0.0001 wt % DNA-MWCNT/5CB relative to pure 5CB, and no improvement was observed when the concentrations are increased. This might be due to the small dielectric anisotropy of DNA that will reduce the composite system’s dielectric anisotropy or due to the weakened adsorption of impure ions by DNA-wrapped nanotubes that will decrease the effective electric field and play a dominant role and finally result in an increase in the threshold voltage, but it is still lower than that of pure 5CB.…”

“…This is also consistent with the reports in the literature. 22,33 However, the U th decreased only by 1.04% for the composite of 0.0001 wt % DNA-MWCNT/5CB relative to pure 5CB, and no improvement was observed when the concentrations are increased. This might be due to the small dielectric anisotropy of DNA that will reduce the composite system's dielectric anisotropy or due to the weakened adsorption of impure ions by DNA-wrapped nanotubes that will decrease the effective electric field and play a dominant role and finally result in an increase in the threshold voltage, but it is still lower than that of pure 5CB.…”

“…Giovanni De Filpo et al showed that single-walled carbon nanotubes (SWCNTs) with high aspect ratio could be arranged along the director, increasing the electrical conductivity and decreasing the reorientation field, so even a small amount of doping could be beneficial to reduce the threshold voltage and driving voltage of LCD significantly. Deepa Singh et al also found a 20–30% reduction in threshold voltage and an increase in dielectric anisotropy when SWCNTs were doped into NLCs. Although many properties of NLCs have been greatly improved by the addition of CNTs, there are still many difficulties for their composites in the application field of LCDs.…”

Gold Nanorod-Induced Effects in a Mesogenic Compound 4-(trans-4-n-Hexylcyclohexyl) isothiocyanatobenzene

“…The samples were taken in homeotropic (for measuring ε ∥ ′ ) and planar (for measuring ε ⊥ ′ ) cells which force the LC molecules to get aligned parallel and perpendicular to the surfaces of the electrodes, respectively, leading to increase in the stability of the mesophase. − ,, The dielectric anisotropy is calculated for pure 6CHBT and its two composites with GNRs by using the values of transverse and longitudinal components of permittivity by the following relation Δε′ = ε ∥ ′ – ε ⊥ ′ . The average permittivity (ε av ′ ) at 25 °C is calculated using the relation ε av ′ = false( ε ∥ prefix′ + 2 ε ⊥ prefix′ false) 3 .…”

“…If any of these factors or both increases, they induce elastic distortion on the director of LC molecules. , Several literature studies also reveal that on addition of nanomaterials, ordering in LC molecules has increased and it has favored several parameters to improve different applications. It is also observed that those composite systems which have either rod-like nanomaterials like SWCNT, MWCNT, etc., or gold nanoparticle has shown a positive sign in nematic ordering. − Not only nanomaterials alter the properties of LCs but there are several properties of nanomaterials that get altered when they are introduced into the surrounding of LC molecules. − …”