Dielectric properties and activation energies of Cu: ZnO dispersed nematic mesogen N-(4-methoxybenzylidene)-4-butylaniline liquid crystal

The dispersion of organic N-benzyl-2-methyl-4-nitroaniline (BNA) in nematic liquid crystals (LCs) is studied. BNA doping decreases the threshold voltage of cell because of the reduced splay elastic constant and increased dielectric anisotropy of the LC mixture. When operated in the high voltage difference condition, the BNA-doped LC cell has a fall time that is five times faster than that of the pure one because of the decrements in the threshold voltage of the cell and rotational viscosity of the LC mixture. The additional restoring force induced by the BNA's spontaneous polarization electric field (SPEF) also assists to decrease the fall time of the LC cell. The decreased viscosity can be deduced from the decrements in phase transition temperature and associated order parameter of the LC mixture. Density functional theory calculation demonstrates that the BNA dopant strengthens the absorbance for blue light, enhances the molecular interaction energy and dipole moment, decreases the molecular energy gap, and thus increases the permittivity of the LC mixture. The calculation also shows that the increased dipole moment, polarizability, and polarizability anisotropy increase the dielectric anisotropy of the LC mixture, which agrees with the experimental results well. BNA doping has a promising application to the fields of LC devices and displays. Nematic liquid crystals (LCs) are extraordinarily responsive and optically uniaxial materials. Nematic LCs have been extensively used in diverse applications, such as optical nonlinearity, optical phase modulators, microdisplays, flat panel displays, optical antennas, and optical switching, due to their electro-optical property and other admirable features 1-5. LCs with a fast response are vital in removing motion blur in moving pictures and resolving cross-talk in 3D displays 6-9. The response time of LCs should be less than 3 ms to diminish motion blur and cross-talk. Several techniques have been proposed to resolve this issue, and they include tuning the viscosity of materials 10 , varying the anchoring energy 11 , changing the electrode shape and driving scheme 12 , changing the cell gap 13 , modifying the guest-host material 14 , and applying new switching modes 15. The improvements in the electro-optical properties of LCs with the dispersion of different gust entities were presented recently. For example, Y. Dai et al. demonstrated that the incorporation of γ-Fe 2 O 3 nanoparticles into LCs results in a response time of 4.75 ms with the application of the overdriving scheme, which is three times faster than pure LCs 16. A response time of around 4 ms was obtained with the addition of a small amount of dye to a polymer-dispersed liquid crystal (PDLC) or functionalized carbon nanotubes dispersed in optically isotropic LCs. However, in this case, the excellent response speed is valid only for operation at a relatively high voltage 17,18. Blue-phase LCs have a response time of 0.5 ms, but they still have drawbacks, such as hysteresis, high operation voltage, and narrow t...

show abstract

“…E is related to according to Eq. ( 7 ) 51 . where R is the molar gas constant, and h is the Plank constant.…”

Section: Resultsmentioning

confidence: 99%

Electro-optical effects of organic N-benzyl-2-methyl-4-nitroaniline dispersion in nematic liquid crystals

Selvaraj

Karthick

Brahadeeswaran

et al. 2020

Sci Rep

View full text Add to dashboard Cite

show abstract

“…The relaxation frequency shifted toward the higher side with an increase in the concentration of CSQDs in pure MBDA. It can be stated that the relaxation process of pure and CSQD doped system (Mix 1 to Mix 6) was dominated by molecules located at the surface and in bulk regions, respectively [13]. The relaxation frequency was lower in the surface layer because the surface viscosity was greater than the bulk viscosity in the pure nematic.…”

Section: Dielectric Response At Planar Geometrymentioning

confidence: 99%

“…In an aligned nematic phase, the AC electric field produces the transverse molecular rotation (i.e., the molecular rotation about the short axis in a low frequency range) and longitudinal molecular rotation (i.e., about long axis at high frequencies) [13]. However, in the experimental window of the frequency, the relaxation mode about the long axis of the molecular rotation cannot be detected and the relaxation mode about its short axis is usually observed.…”

Section: Field-induced Reorientation Of Liquid Crystal In Qd Doped Sa...mentioning

confidence: 99%

“…However, at higher frequencies, a rapid decrease in its values was observed. This can be explained on the basis of dipolar interaction [13,16] between the CSQDs and nematic MBDA molecules. It is well known that in the absence of an electric field, the dipole moments of CSQDs and nematic molecules do not align parallel to each other.…”

Section: Dielectric Response At Planar Geometrymentioning

confidence: 99%

“…It explained the self-assembled arrays of CSQDs in the nematic phase and reduction in the screening effect by the ion trapping effect of CSQDs. Misra et al [13] explained the influence of dispersing Cu:ZnO in nematic MBBA liquid crystal and studied the dielectric properties and activation energies for the dispersed systems. Singh et al [14] reviewed the effect of doping nanoparticles in nematic liquid crystals.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Effect of Doping of Cd1−xZnxS/ZnS Core/Shell Quantum Dots in Negative Dielectric Anisotropy Nematic Liquid Crystal p-Methoxybenzylidene p-Decylaniline

et al. 2021

Self Cite

View full text Add to dashboard Cite

We report the effect of the doping of Cd1−xZnxS/ZnS core/shell quantum dots (CSQDs) in nematic liquid crystal p-methoxybenzylidenep-decylaniline (MBDA) at 0.05 wt/wt%, 0.1 wt/wt%, 0.15 wt/wt%, 0.2 wt/wt%, 0.25 wt/wt%, and 0.3 wt/wt% concentrations of CSQDs in MBDA. Dielectric parameters with and without bias with respect to frequency have been investigated. The change in electro-optical parameters with temperature has also been demonstrated. The increase in the mean dielectric permittivity was found due to the large dipole moment of CSQDs, which impose stronger interactions with the liquid crystal molecules. The dielectric anisotropy changes sign on doping CSQDs in MBDA liquid crystal. It was concluded that the CSQD doping noticeably increased the dielectric permittivity of nematic MBDA in the presence of an electric field. The doping of CSQDs in nematic MBDA liquid crystal reduced the ion screening effect effectively. This phenomenon is attributed to the competition between the generated ionic impurities during the assembling process and the ion trapping effect of the CSQDs. The rotational viscosity of nematic liquid crystal decreased with increasing concentration of the CSQDs, with a faster response time observed for the 0.05 wt/wt% concentration. The birefringence of the doped system increased with the inclusion of CSQDs in MBDA. These results find application in the field of display devices, phase shifters, LC – gratings, TIR waveguide, industries, and projectors.

show abstract

Effect of Guest Particles on the Functional Dielectric Properties of Materials for Display Application

Avaish,

Warsi,

Dwivedi

et al. 2024

Macromolecular Symposia

View full text Add to dashboard Cite

In this study the dielectric properties are experimentally studied and also analyzed the influence of guest particles on the functional properties of various liquid crystals. The polar and elastic energy of the nanoparticles is found to affect the functional energy of pure suspension. In addition to this, the functional dielectric anisotropy of the dispersed system takes modified form. In this study experiments are performed on various materials to find dielectric anisotropy and also found in good agreement with theoretical explanation.

show abstract

Dielectric properties and activation energies of Cu: ZnO dispersed nematic mesogen N-(4-methoxybenzylidene)-4-butylaniline liquid crystal

Cited by 25 publications

References 43 publications

Electro-optical effects of organic N-benzyl-2-methyl-4-nitroaniline dispersion in nematic liquid crystals

Electro-optical effects of organic N-benzyl-2-methyl-4-nitroaniline dispersion in nematic liquid crystals

Effect of Doping of Cd1−xZnxS/ZnS Core/Shell Quantum Dots in Negative Dielectric Anisotropy Nematic Liquid Crystal p-Methoxybenzylidene p-Decylaniline

Effect of Guest Particles on the Functional Dielectric Properties of Materials for Display Application

Contact Info

Product

Resources

About