Improvement of the dynamic responses of liquid crystal mixtures through γ-Fe<sub>2</sub>O<sub>3</sub> nanoparticle doping and driving mode adjustment

Dai, Yayu; Gao, Lin; Wang, Mohan; Zhao, Xueqian; Li, Tong; Tang, Zongyuan; Li, Zhenjie; Xing, Hongyan; Zhu, Jiliang; Ye, Wenjiang; Meng, Xiangshen; He, Zhenghong; Li, Jian; Cai, Minglei; Yang, Changyong

doi:10.1080/02678292.2019.1593529

Cited by 15 publications

(3 citation statements)

References 41 publications

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“…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.…”

Section: Introductionmentioning

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

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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...

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Section: Introductionmentioning

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

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“…In our early work, the LC doped with γ-Fe2O3 NPs can increase the dielectric constant and improve the electro-optical response [13,14]. In addition, the transmittance curves with angle (T-θ) were measured using θ-scanning technology to investigate the anisotropic optical properties of ferrofluids and LCs [15,16].…”

Section: Introductionmentioning

confidence: 99%

Reveal linear optical effects of the liquid crystal by Stokes-Mueller calculus and θ-scan technology

Meng

Lin

et al. 2022

Preprint

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Based on the Stokes-Mueller calculus, linear optical effects of liquid crystals were investigated using the θ-scan technology. Usually, when a circularly polarized light beam passes through an anisotropic optical medium, the transmitted light beam behaves as elliptically polarized light. The Stokes-Mueller calculus shows that the change of the transmitted light intensity includes the linear optical characteristics of the medium, such as dichroism, birefringence, and ellipticity. Meanwhile, these optical characteristics can be probed simultaneously from the transmittance curve using an angular scan (T-θ), i.e., θ-scan technology. As the nanoparticle (NP) concentration in the liquid crystal increases from 0 to 0.1 wt%, the apparent dichroism monotonously decreases with the NP concentration. LC molecules are highly birefringent, resulting in Nπ uncertainty on the T-θ curve. As a result, when the NP concentration rises from 0 to 0.06 wt %, the ellipticity decreases; when the NP concentration rises from 0.06 wt % to 0.1 wt %, the ellipticity increases. However, from the change in the apparent phase delay with the NP concentration, Nπ can be distinguished. As well, birefringence decreases monotonously with the NP concentration.

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“…The LC doped with γ-Fe 2 O 3 nanoparticles has the advantages of extremely fast response speed (compared with pure LC, the response speed of doped LC can be increased by 3 times), low driving voltage and so on. [9] It is a material that can significantly improve the characteristics of LCD. However, the stability of LC systems is a necessary factor to determine whether the LC can be widely used in the display field.…”

Section: Introductionmentioning

confidence: 99%

Stability of liquid crystal systems doped with γ-Fe₂O₃ nanoparticles*

Zhang¹,

Liu²,

Tang³

et al. 2021

Chinese Phys. B

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In order to explore the stability of a liquid crystal (LC) system doped with γ-Fe2O3 nanoparticles, the physical properties (clearing point, dielectric properties), electro-optical properties and residual direct-current voltage (RDCV) of the doped LC system were measured and evaluated at different times. First, the temperature was controlled by precision hot stage, and the clearing point temperature of doped LC was observed and measured by a polarized optical microscope. Using a precision LCR meter, we measured the capacitance-voltage curves of the doped LC system at the temperature of 27 °C. The dielectric constant of doped LC was calculated by the dualcell capacitance method. Then, the electro-optical properties of the doped LC system were measured. Finally, the RDCV of the doped LC system was measured and calculated. After five months, the parameters of the doped LC system were re-measured and analyzed under the same conditions to evaluate its stability. The experimental results show that, within five months, the clearing point change rate of doped LC is in the range of 0.24%–1.37%, the change of dielectric anisotropy is in the range of 0.035–0.2, the curves of electro-optical properties are basically fitted, and the change rate of saturated RDCV is about 11.2%, which basically indicate that the LC system doped with γ-Fe2O3 nanoparticles has good stability.

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Improvement of the dynamic responses of liquid crystal mixtures through γ-Fe₂O₃ nanoparticle doping and driving mode adjustment

Cited by 15 publications

References 41 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

Reveal linear optical effects of the liquid crystal by Stokes-Mueller calculus and θ-scan technology

Stability of liquid crystal systems doped with γ-Fe₂O₃ nanoparticles*

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Improvement of the dynamic responses of liquid crystal mixtures through γ-Fe2O3 nanoparticle doping and driving mode adjustment

Cited by 15 publications

References 41 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

Reveal linear optical effects of the liquid crystal by Stokes-Mueller calculus and θ-scan technology

Stability of liquid crystal systems doped with γ-Fe2O3 nanoparticles*

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Product

Resources

About

Improvement of the dynamic responses of liquid crystal mixtures through γ-Fe₂O₃ nanoparticle doping and driving mode adjustment

Stability of liquid crystal systems doped with γ-Fe₂O₃ nanoparticles*