Electrically switchable multi-stable cholesteric liquid crystal based on chiral ionic liquid

Lu, Hongbo; Xu, Wei; Song, Zhigang; Zhang, Shanna; Qiu, Longzhen; Wang, Xianghua; Zhang, Guobing; Hu, Juntao; Lv, Guoqiang

doi:10.1364/ol.39.006795

Cited by 30 publications

(17 citation statements)

References 17 publications

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“…Subsequently, while switching off the voltage, the helical configurations of the ULH and the FC-2 states in the voltage-off state were stably preserved, with neither molecular nor ionic perturbation. It is worth mentioning that the ULH and FC-2 textures, obtained via the EHD effect in this study, are in good agreement with previous studies, claiming them as stable states in planar-aligned CLCs with positive [19,25] or negative dielectric anisotropy [26,27]. In contrast, the FC-1 was generated by dielectric coupling between the LC molecules and the electric field, so that the value of V FC-1 was lower than the onset voltage for triggering the EHD instability.…”

Section: Textural Formations In the Clc Defect Layer And The Driving supporting

confidence: 92%

Photonic Bandgap–Cholesteric Device with Electrical Tunability and Optical Tristability in Its Defect Modes

Hsiao

Lee

2017

Crystals

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This study proposes a hybrid structure for a one-dimensional (1D) photonic crystal (PC) comprising a tristable cholesteric liquid crystal (CLC) as the defect layer. The CLC exhibits three optically stable states: the Grandjean planar (P), focal conic (FC), and uniform lying helix (ULH) configurations. Specifically, the reflection band of the CLC is set within the photonic bandgap (PBG) of the 1D PC. While the ULH and the FC states can be regarded as the light-on and light-off states for defect-mode peaks in the visible spectrum, respectively, switching the device from the ULH to the P state enables suppression of the transmission of partial defect modes within the PBG. This device possesses many alluring features, such as optical tristability at null applied voltage and transmission tunability of the defect modes, providing a new pathway for the design of multifunctional and energy-efficient optical switches, light shutters, multichannels, and wavelength selectors.

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Section: Textural Formations In the Clc Defect Layer And The Driving supporting

confidence: 92%

Photonic Bandgap–Cholesteric Device with Electrical Tunability and Optical Tristability in Its Defect Modes

Hsiao

Lee

2017

Crystals

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“…A miscibility of CILs with LCs within the nematic phase, besides sufficiently high helical twisting power ( HTP ) of the chiral dopant, seems to be the most crucial parameter for these applications. Such mixtures have already been studied in the literature [ 1 , 2 , 7 , 8 , 9 , 10 , 11 , 12 ], mainly with respect to their electrically induced effects. In our recent paper [ 9 ], chiral ionic compounds, formed by mesogenic chiral phenylpyridine derivative and strong organic acids, were miscible, to some extent, with the nematic LC host.…”

Section: Introductionmentioning

confidence: 99%

On the Miscibility of Nematic Liquid Crystals with Ionic Liquids and Joint Reaction for High Helical Twisting Power Product(s)

et al. 2021

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Mixtures of nematic liquid crystals (LCs) with chiral ionic liquids (CILs) may find application as active materials for electrically driven broadband mirrors. Five nematic liquid crystal hosts were mixed with twenty three ionic liquids, including chiral ones, and studied in terms of their miscibility within the nematic phase. Phase diagrams of the mixtures with CILs which exhibited twisted nematic phase were determined. Miscibility, at levels between 2 and 5 wt%, was found in six mixtures with cyanobiphenyl-based liquid crystal host—E7. On the other hand, the highest changes in the isotropization temperature was found in the mixtures with isothiocyanate-based liquid crystal host—1825. Occurrence of chemical reactions was found. A novel chiral binaphtyl-based organic salt [N11116][BNDP] was synthesized and, in reaction to the 1825 host, resulted in high helical twisting power product(s). Selectivity of the reaction with the isothiocyanate-based liquid crystal was found.

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“…Theoretical description of transitions between the stable states in ChLC is an important problem in fundamental studies of liquid crystals (LC) and is of critical importance in the design of optical liquid crystal displays, where efficient switching between the optical states is needed for recording the visual information. Several schemes have been proposed to induce transitions between stable states in ChLC, involving application of the external field pulses [1, [13][14][15][16] and pressure [17]. Thermal fluctuations can induce spontaneous transitions and, therefore, affect the stability of optic states in ChLC.…”

Section: Introductionmentioning

confidence: 99%

“…The preparation of a ChLC system in a particular state can be destroyed by thermally activated transitions to other available states. Typically, P and FC structures are very stable against thermal fluctuations due to the large energy barrier separating the states [13,16,18]. However, energy barriers can be tuned by external fields driving the system to the regime where spontaneous thermally activated transitions can not be neglected.…”

Section: Introductionmentioning

confidence: 99%

Energy surface and minimum energy paths for Fréedericksz transitions in bistable cholesteric liquid crystals

et al. 2016

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The multidimensional energy surface of a cholesteric liquid crystal in a planar cell is investigated as a function of spherical coordinates determining the director orientation. Minima on the energy surface correspond to the stable states with particular director distribution. External electric and magnetic fields deform the energy surface and positions of minima. It can lead to the transitions between states, known as the Fréedericksz effect. Transitions can be continuous or discontinuous depending on parameters of the liquid crystal which determine an energy surface. In a case of discontinuous transition when a barrier between stable states is comparable with the thermal energy, the activation transitions may occur, and it leads to the modification of characteristics of the Fréedericksz effect with temperature without explicit temperature dependencies of liquid crystal parameters. A minimum energy path between stable states on the energy surface for the Fréedericksz transition is found using the geodesic nudged elastic band method. Knowledge of this path, which has maximal statistical weight among all other paths, gives the information about a barrier between stable states and configuration of director orientation during the transition. It also allows one to estimate the stability of states with respect to the thermal fluctuations and their lifetime when the system is close to the Fréedericksz transition.

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Electrically switchable multi-stable cholesteric liquid crystal based on chiral ionic liquid

Cited by 30 publications

References 17 publications

Photonic Bandgap–Cholesteric Device with Electrical Tunability and Optical Tristability in Its Defect Modes

Photonic Bandgap–Cholesteric Device with Electrical Tunability and Optical Tristability in Its Defect Modes

On the Miscibility of Nematic Liquid Crystals with Ionic Liquids and Joint Reaction for High Helical Twisting Power Product(s)

Energy surface and minimum energy paths for Fréedericksz transitions in bistable cholesteric liquid crystals

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