Electro-optical and dielectric properties of TiO2 nanoparticles in nematic liquid crystals with high dielectric anisotropy

Chi-Yen Huang, Pravinraj Selvaraj, Govindan Senguttuvan, Che Ju Hsu

Research output: Contribution to journalArticle

Abstract

The electrical, optical and dielectric performance of high-dielectric-constant TiO2 nanoparticles (NPs) dispersed in nematic liquid crystals (NLCs) with high dielectric anisotropy is demonstrated. TiO2 doping decreases the pretilt angle of the NLC cell because of the increase in Van der Waals interaction between the NLC molecule and alignment layer. Moreover, TiO2 doping strengthens the electric field in the NLC bulk and suppresses the ionic screen effect on the substrate surface, thus decreasing the threshold and driving voltages of the NLC cell. The measured field-off response time and estimated conductivity initially increase and then decrease with increased TiO2 concentrations. This phenomenon is due to the antagonism between the entrained ion impurities during fabrication and the ion harvest effect of TiO2 NPs. Dielectric spectral measurements reveal that TiO2 doping changes the relative permittivity and dielectric anisotropy of NLCs because of the changed space–charge polarisation and order parameters in the NLC bulk. The physical mechanisms are discussed in detail accordingly.

Original languageEnglish
Article number110902
JournalJournal of Molecular Liquids
Volume286
DOIs
Publication statusPublished - 2019 Jul 15

Fingerprint

Nematic liquid crystals
Dielectric properties
dielectric properties
Anisotropy
Optical properties
liquid crystals
Nanoparticles
optical properties
nanoparticles
anisotropy
Doping (additives)
screen effect
Permittivity
Ions
permittivity
cells
threshold voltage
ions
alignment
Electric fields

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Condensed Matter Physics
  • Spectroscopy
  • Physical and Theoretical Chemistry
  • Materials Chemistry

Cite this

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title = "Electro-optical and dielectric properties of TiO2 nanoparticles in nematic liquid crystals with high dielectric anisotropy",
abstract = "The electrical, optical and dielectric performance of high-dielectric-constant TiO2 nanoparticles (NPs) dispersed in nematic liquid crystals (NLCs) with high dielectric anisotropy is demonstrated. TiO2 doping decreases the pretilt angle of the NLC cell because of the increase in Van der Waals interaction between the NLC molecule and alignment layer. Moreover, TiO2 doping strengthens the electric field in the NLC bulk and suppresses the ionic screen effect on the substrate surface, thus decreasing the threshold and driving voltages of the NLC cell. The measured field-off response time and estimated conductivity initially increase and then decrease with increased TiO2 concentrations. This phenomenon is due to the antagonism between the entrained ion impurities during fabrication and the ion harvest effect of TiO2 NPs. Dielectric spectral measurements reveal that TiO2 doping changes the relative permittivity and dielectric anisotropy of NLCs because of the changed space–charge polarisation and order parameters in the NLC bulk. The physical mechanisms are discussed in detail accordingly.",
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Electro-optical and dielectric properties of TiO2 nanoparticles in nematic liquid crystals with high dielectric anisotropy. / Huang, Chi-Yen; Selvaraj, Pravinraj; Senguttuvan, Govindan; Hsu, Che Ju.

In: Journal of Molecular Liquids, Vol. 286, 110902, 15.07.2019.

Research output: Contribution to journalArticle

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T1 - Electro-optical and dielectric properties of TiO2 nanoparticles in nematic liquid crystals with high dielectric anisotropy

AU - Huang, Chi-Yen

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AB - The electrical, optical and dielectric performance of high-dielectric-constant TiO2 nanoparticles (NPs) dispersed in nematic liquid crystals (NLCs) with high dielectric anisotropy is demonstrated. TiO2 doping decreases the pretilt angle of the NLC cell because of the increase in Van der Waals interaction between the NLC molecule and alignment layer. Moreover, TiO2 doping strengthens the electric field in the NLC bulk and suppresses the ionic screen effect on the substrate surface, thus decreasing the threshold and driving voltages of the NLC cell. The measured field-off response time and estimated conductivity initially increase and then decrease with increased TiO2 concentrations. This phenomenon is due to the antagonism between the entrained ion impurities during fabrication and the ion harvest effect of TiO2 NPs. Dielectric spectral measurements reveal that TiO2 doping changes the relative permittivity and dielectric anisotropy of NLCs because of the changed space–charge polarisation and order parameters in the NLC bulk. The physical mechanisms are discussed in detail accordingly.

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