Theoretical consideration of the drop in threshold voltage at low frequencies in nematic liquid crystals

Oh‐e, Masahito; Kondo, K.; Kando, Yasuhiko

doi:10.1080/02678299408036551

Cited by 10 publications

(2 citation statements)

References 16 publications

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“…Moreover, one has to realize that the nematic layer is confined by metallically coated glass plates with a thin polymeric alignment film on top, which themselves may have fairly complicated electric properties. Thus the whole system is represented as an equivalent circuit diagram (see, e.g., [23,24]) where the total voltage applied to the cell is different from "theoretical" results like U c , which represent only the voltage drop over the nematic layer. The necessary corrections to U c are not easy to model and would also require systematic measurements on the empty cell.…”

Section: Discussionmentioning

confidence: 99%

Flexoelectricity and pattern formation in nematic liquid crystals

Krekhov

Pesch²,

Buka³

2011

Phys. Rev. E

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We present in this paper a detailed analysis of the flexoelectric instability of a planar nematic layer in the presence of an alternating electric field (frequency ω), which leads to stripe patterns (flexodomains) in the plane of the layer. This equilibrium transition is governed by the free energy of the nematic which describes the elasticity with respects to the orientational degrees of freedom supplemented by an electric part. Surprisingly the limit ω → 0 is highly singular. In distinct contrast to the dc-case, where the patterns are stationary and time-independent, they appear at finite, small ω periodically in time as sudden bursts. Flexodomains are in competition with the intensively studied electro-hydrodynamic instability in nematics, which presents a non-equilibrium dissipative transition. It will be demonstrated that ω is a very convenient control parameter to tune between flexodomains and convection patterns, which are clearly distinguished by the orientation of their stripes.

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Section: Discussionmentioning

confidence: 99%

Flexoelectricity and pattern formation in nematic liquid crystals

Krekhov

Pesch²,

Buka³

2011

Phys. Rev. E

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“…Generally, if liquid crystals are themselves ionic compounds or if ionic impurities exist in a liquid crystal cell, the effective internal electric field applied to the liquid crystals is reduced owing to the formation of an electric double layer. − Consequently, ionic compounds cannot be used as materials for liquid crystal display devices because the ability of the device deteriorates. However, since the hydrogen-bonded liquid crystalline complexes as described above are nonionic compounds, they are considered to be applicable as materials for nematic liquid crystal display devices.…”

Section: Introductionmentioning

confidence: 99%

Response of a Hydrogen-Bonded Liquid Crystal to an Applied Electric Field Accelerated by a Poly(γ-benzyl l-glutamate) Chemical Reaction Alignment Film

1997

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Poly(γ-benzyl l-glutamate) (PBLG) was bonded covalently to a flat substrate, and it formed an aligned dipole layer (PBLG−CRA film). Using the PBLG−CRA film as an orienting film for a nematic hydrogen-bonded liquid crystalline complex, 6OBA−9Py (formed from 4-(hexyloxy)benzoic acid (6OBA) and 4-nonylpyridine (9Py)), complexes, not only in the vicinity of the CRA film but also in the bulk layer, were able to respond more rapidly to an applied electric field when using a rubbed polyimide film, and they became responsive at frequencies in the MHz region. We conclude that the PBLG−CRA film has a dynamic orienting force, that dipole−dipole interaction takes place between the interfacial 6OBA−9Py complexes and the PBLG molecules, and that the movement of the interfacial 6OBA−9Py complexes is smoothly transferred to the bulk layer because the electric state of the complex 6OBA−9Py in the bulk changes under the influence of the CRA film.

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