Ion Transport in Liquid Crystals

Neyts, Kristiaan; Beunis, Filip

doi:10.1002/9783527671403.hlc032

Cited by 23 publications

(23 citation statements)

References 38 publications

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“…The conductivity of nematics is of an ionic type [22,23]. Ions are always present in liquid crystals, representing synthetic impurities, or being produced at electrodes, through dissociation of neutral molecules, absorption from surroundings such as glue, alignment layers, etc.…”

Section: Introductionmentioning

confidence: 99%

“…Ions are always present in liquid crystals, representing synthetic impurities, or being produced at electrodes, through dissociation of neutral molecules, absorption from surroundings such as glue, alignment layers, etc. [23]. We measured the concentration using the transient current technique and determined it to be on the order of Equation (1) has been deduced in Ref.…”

Section: Introductionmentioning

confidence: 99%

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Nonlinear Electrophoresis of Colloids Controlled by Anisotropic Conductivity and Permittivity of Liquid-Crystalline Electrolyte

et al. 2017

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Liquid crystal electrolytes enable nonlinear electrophoresis of colloidal particles with velocities proportional to the square of the applied field. We demonstrate that the magnitude and even the polarity of electrophoretic mobility can be controlled by the anisotropy of electric conductivity and dielectric permittivity of the liquid crystal. In particular, reversal of electrophoretic mobility can be triggered either by temperature or composition changes that alter the signs of the conductivity and permittivity anisotropies. Controllable reversal of mobility adds to the list of advantages of anisotropic electrolytes over their isotropic counterparts. † olavrent@kent.edu

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Nonlinear Electrophoresis of Colloids Controlled by Anisotropic Conductivity and Permittivity of Liquid-Crystalline Electrolyte

et al. 2017

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“…The LC layer is not conductive, but in practice the LC needs to be driven with low frequency AC electric fields (e.g., 1 kHz) to avoid ion drift. 20 The permittivity of the LC is anisotropic and is given by the 3 Â 3 tensor e. The elements of the tensor depend on the orientation of the average molecular orientation (i.e., the director, given by the vector n) according to the equation…”

Section: Theoretical Modelmentioning

confidence: 99%

“…AC voltages are necessary in LC devices as DC voltages result in unwanted movement of small concentration of ions in the LC material. 20 In one-dimensional beam steering devices, it is desired to have a linear refractive index profile along one direction. Approximately, this means that also the voltage variation from one contacting electrode to the other needs to be linear.…”

Section: Introductionmentioning

confidence: 99%

Optimization of liquid crystal devices based on weakly conductive layers for lensing and beam steering

Beeckman

Nys

Willekens

et al. 2017

Journal of Applied Physics

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Liquid crystals are mostly known for their use in displays, but over the past decade these materials have been applied in a number of other devices such as tunable lenses or beam steering devices. A common technique to realize a gradual electric field profile as is required to obtain a gradual refractive index profile in these applications is the use of weakly conductive materials. The weakly conductive layers are able to spread the voltage profile which is applied through well-conductive electrodes at the side of the weakly conductive layer. The simulation and design of such structures is not trivial because two or three dimensional quasi-static electric field profiles need to be calculated. This is due to the fact that the resistivity of the conductive layers and the dielectric properties of the liquid crystal are coupled. An exact solution requires solving a number of coupled differential equations. In this paper, we develop a model to simulate the RC-effects with an approximate model

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“…The most important are ionic dissociations of the residual impurities [2,29], ionic contamination during the manufacturing process (the alignment layers, the glue, and the filling process are the sources of the contaminations) [19,30], charge injection, charge transfer and electrochemical reactions in the electrodes and/or in the bulk of the liquid crystal cell [2,[31][32][33][34][35], and aging (chemical decomposition and self -dissociation of liquid crystals) [2,11]. The simultaneous presence of more than one of the processes mentioned above is a very common thing and should be considered by experimentalists [2,36,37].…”

Section: Ions In Liquid Crystalsmentioning

confidence: 99%

Nano-Objects and Ions in Liquid Crystals: Ion Trapping Effect and Related Phenomena

2015

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Abstract:The presence of ions in liquid crystals is one of the grand challenges that hinder the application of liquid crystals in various devices, which include advanced 3-D and flexible displays, tunable lenses, etc. Not only do they compromise the overall performance of liquid crystal devices, ions are also responsible for slow response, image sticking, and image flickering, as well as many other negative effects. Even highly purified liquid crystal materials can get contaminated during the manufacturing process. Moreover, liquid crystals can degrade over time and generate ions. All of these factors raise the bar for their quality control, and increase the manufacturing cost of liquid crystal products. A decade of dedicated research has paved the way to the solution of the issues mentioned above through merging liquid crystals and nanotechnology. Nano-objects (guests) that are embedded in the liquid crystals (hosts) can trap ions, which decreases the ion concentration and electrical conductivity, and improves the electro-optical response of the host. In this paper, we (i) review recently published works reporting the effects of nanoscale dopants on the electrical properties of liquid crystals; and (ii) identify the most promising inorganic and organic nanomaterials suitable to capture ions in liquid crystals.

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Ion Transport in Liquid Crystals

Cited by 23 publications

References 38 publications

Nonlinear Electrophoresis of Colloids Controlled by Anisotropic Conductivity and Permittivity of Liquid-Crystalline Electrolyte

Nonlinear Electrophoresis of Colloids Controlled by Anisotropic Conductivity and Permittivity of Liquid-Crystalline Electrolyte

Optimization of liquid crystal devices based on weakly conductive layers for lensing and beam steering

Nano-Objects and Ions in Liquid Crystals: Ion Trapping Effect and Related Phenomena

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