43‐1: Tri‐stable Cholesteric Liquid Crystal Smart Window

Li, Cheng-Chang; Tseng, Heng-Yi; Chen, Chun-Wei; Wang, Chun-Ta; Jau, Hung‐Chang; Wu, Yu‐Ching; Hsu, Wen‐Hao; Lin, Tung‐Ching

doi:10.1002/sdtp.12434

Cited by 4 publications

(2 citation statements)

References 16 publications

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“…The bandwidth is currently measured such as the width of the bandgap at half height, which is usually limited to a few tens of nanometers in the visible spectrum because the birefringence is typically limited to 0.5. While the narrow bandwidth is desirable for applications in optical filters, narrow-band polarizers, thermography, and sensors, it also becomes a drawback for innovative applications such as full-color or reflective polarizer-free displays [28][29][30][31][32], broadband polarizers [33,34], and smart windows [35][36][37][38][39].…”

Section: Bragg Reflection and Photonic Band Gapmentioning

confidence: 99%

Templated Twist Structure Liquid Crystals and Photonic Applications

Gao

Ding

2022

Polymers

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Twist structure liquid crystals (TSLCs) have attracted increasing attention in photonic applications due to their distinct properties: Bragg reflection, scattering, and optical rotation. However, there exist some issues due to the defects of TSLCs: weak thermal stability, narrow bandwidth, and complicated fabrication. In this review, we introduce the templating technique which includes device structure, templating process, and photonic properties of templated TSLCs to improve the issues. Furthermore, a variety of photonic applications including lasing, optical filters and gratings based on TSLCs with polymer templates are presented. Additionally, other applications of TSLCs are briefly introduced. Finally, the remaining challenges and future perspectives of templated TSLCs are proposed.

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Section: Bragg Reflection and Photonic Band Gapmentioning

confidence: 99%

Templated Twist Structure Liquid Crystals and Photonic Applications

Gao

Ding

2022

Polymers

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“…On the basis of this method, Salter et al reported that the resulting ULH in a planar-aligned cell with 90 • -twisted rubbing is more uniform than those of hybrid-aligned cells and of the planar-aligned cells with parallel (0 • or 180 • ) rubbing [13]. Without undergoing the temperature-cooling process, voltage-generated ULH alignment has also been obtained in planar-aligned CLC cells by providing an extra mechanical force to induce shear flow in the meantime [14][15][16], using ion-rich positive nematic host to permit electrohydrodynamic flow by low-frequency voltages [17,18], controlling voltage conditions precisely to induce the nematic-to-CLC structural transition [19], optimizing the pretilt angle as well as the anchoring energy [20], or by designing a tri-electrode configuration [21,22]. For the surface-treatment method, the concept stems from the modification in surface morphology of alignment layers, enabling periodic anchoring for realizing the ULH structure spontaneously.…”

Section: Introductionmentioning

confidence: 99%

Electro-Thermal Formation of Uniform Lying Helix Alignment in a Cholesteric Liquid Crystal Cell

Lee

2019

Crystals

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We demonstrated previously that the temperature of a sandwich-type liquid crystal cell with unignorable electrode resistivity could be electrically increased as a result of dielectric heating. In this study, we take advantage of such an electro-thermal effect and report on a unique electric-field approach to the formation of uniform lying helix (ULH) texture in a cholesteric liquid crystal (CLC) cell. The technique entails a hybrid voltage pulse at frequencies f1 and, subsequently, f2, which are higher and lower than the onset frequency for the induction of dielectric heating, respectively. When the cell is electrically sustained in the isotropic phase by the voltage pulse of V = 35 Vrms at f1 = 55 kHz or in the homeotropic state with the enhanced ionic effect at V = 30 Vrms and f1 = 55 kHz, our results indicate that switching of the voltage frequency from f1 to f2 enables the succeeding formation of well-aligned ULH during either the isotropic-to-CLC phase transition at f2 = 1 kHz or by the electrohydrodynamic effect at f2 = 30 Hz. For practical use, the aligning technique proposed for the first time in this study is more applicable than existing alternatives in that the obtained ULH is adoptable to CLCs with positive dielectric anisotropy in a simple cell geometry where complicated surface pretreatment is not required. Moreover, it is electrically switchable to other CLC textures such as Grandjean planar and focal conic states without the need of a temperature controller for the phase transition, the use of ion-rich LC materials, or mechanical shearing for textural transition.

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