Dynamic control of colorful reflection toward practical cholesteric liquid crystal displays

Inoue, Y.; Moritake, Hiroshi

doi:10.1364/oe.24.023027

Cited by 12 publications

(9 citation statements)

References 22 publications

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“…However, for large angle α, we observed spectral blue shift of selective reflection from the CLC on the PPFVB surface. Similar results with these spectral shift and broadening of PBGs have been observed in transmission spectra of the electrical switching modes of CLC gels and the transient state with two-dimensional periodic undulations of helical structures induced by electric field applications, that is, the Helfrich deformation. ,− It is noted that deformed CLC structures on PPFVB surfaces are durable without additional solidification process and can be obtained from only surface controls without applications of external fields. In the present system, it was difficult to determine a threshold value of surface energy for cholesteric deformations on the PPFVB surface.…”

Section: Resultssupporting

confidence: 73%

Manipulation of Structural Colors in Liquid-Crystal Helical Structures Deformed by Surface Controls

Lim¹,

Bae²,

Jeong

et al. 2018

ACS Appl. Mater. Interfaces

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Structural colors from cholesteric liquid crystals (CLCs) are manipulated by changing the only surface anchoring energy of an alignment layer. This behavior comes from the fact that weak surface energy of the perfluoropolymer induces the tilting of the cholesteric helix. Such deformed CLC structures with durability are successfully demonstrated without any external field applications and additional solidification processes. In addition, electrical tunings of structural colors from the deformed CLCs occur at very low operating voltages, compared to those of conventional CLC structures. On the basis of easy and simple fabrication, high durability, electrical tunability at low operating voltages, and the unique optical characteristics, the new deformed CLC structure could lead to extension in applications of CLCs, including multifunctional sensors, displays, and lasers.

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Section: Resultssupporting

confidence: 73%

Manipulation of Structural Colors in Liquid-Crystal Helical Structures Deformed by Surface Controls

Lim¹,

Bae²,

Jeong

et al. 2018

ACS Appl. Mater. Interfaces

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“…This shortening of the pitch causes an internal strain until the polymerization is completed. Helfrich deformation occurs because of the competition of different torques from the surface anchoring, the elastic force of LC, and internal strain, − thus resulting in the formation of the large-area disorderly 2D microgrid structure. Movies S1 and S2 (or Figures S3a and S3b) show the dynamic variations in the diffraction pattern of the He–Ne probe during the exposure of the two selected samples (Samples 2 and 6, respectively) to the single UV-laser beam.…”

Section: Resultsmentioning

confidence: 99%

“…However, the free rotation of the cholesteric layers is restricted by the surface anchoring forces provided by the confining substrates with alignment pretreatment and the elastic torques of the CLC itself . As a consequence, the balance among the electric, surface anchoring, and elastic torques causes the periodic fluctuation of the cholesteric layers and the periodic modulation of the orientation of the helical axis and the size of the helical pitch to form a two-dimensional (2D) periodic microgrid pattern ,,, (Figure ). Given that the pattern and periodicity of the 2D microgrid structure crucially depend on the cell and material factors, such as the cell gap and equilibrium pitch, , the formed microstructure in a homemade CLC cell with a uniform pitch usually exhibits high order locally but many grain boundaries globally due to the inhomogeneity of the cell gap.…”

Section: Introductionmentioning

confidence: 99%

Control of Large-Area Orderliness of a 2D Supramolecular Chiral Microstructure by a 1D Interference Field

Jiang

Wang

Zhang

et al. 2021

ACS Appl. Mater. Interfaces

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Self-organized periodic micro/nanostructures caused by stimulus-responsive structural deformation often occur in anisotropic self-assembled supramolecular systems (e.g., liquid crystal systems). However, the long-range orderliness of these structures is often beyond control. In this article, we first demonstrate that a large-area disordered two-dimensional (2D) microgrid chiral structure appears in the cholesteric liquid crystal (CLC) reactive mixture because of the photopolymerization-induced Helfrich deformation effect under exposure to the single UV-laser beam. The result is attributed to the impact of an internal longitudinal strain, which is caused by the pitch contraction of the CLC-monomer region through the continuing compression of the thickening CLC polymer layer adhered on the illuminated substrate of the sample during photopolymerization. The experimental results further show that a one-dimensional (1D) UV-laser interference field can be used to effectively control the postformed 2D microgrid structure to arrange in an orderly manner throughout the large exposed area (an order of centimeter). The optimum ability for controlling the orderliness of the microgrid structure can be achieved if the spacing width of the interference field approximates the periodicity of the postformed 2D microgrids. Several factors, such as the pitch of the CLC mixture and the included angle and intensity of the two interfering laser beams, which influence the orderliness and properties of the 2D microgrid structure, are explored in this study. The result of this research opens a new page to improve the applicability of the Helfrich deformation phenomenon and further provides a reference platform for manipulating, modifying, and even tailoring periodic micro/ nanostructures in self-organized supramolecular soft-matter systems for application in advanced optics/photonics.

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“…Cholesteric DOI: 10.1002/adom.202300296 liquid crystals (CLCs) exhibit structural colors due to their property of selectively reflecting light by means of a helical self-assembled structure in which the dielectric constant and refractive index are periodically arranged. These properties make them highly useful for dynamic display, [1][2][3] information storage, [4][5][6] and optical security applications. [7][8][9] Spherical CLCs particles are favored by researchers due to their angle-independent structural coloration.…”

Section: Introductionmentioning

confidence: 99%

Particle Size Controlled Chiral Structural Color of Monodisperse Cholesteric Liquid Crystals Particles

Liu

Gao

et al. 2023

Advanced Optical Materials

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Cholesteric liquid crystals (CLCs) are becoming increasingly popular due to their unique chiral structural color. Unlike ordinary CLCs materials, CLCs particles exhibit angle‐independence, making them particularly noteworthy. However, currently, there are limited effective methods for controlling the structural color of CLCs particles, other than adjusting the concentration of chiral dopants or introducing stimuli‐responsive groups. Here, a scalable and cost‐effective process for preparing monodisperse CLCs particles via dispersion polymerization is reported. By making CLCs into micrometer‐sized monodisperse spheres, the helical pitch of CLCs can be varied according to its particle size, and the resulting structural color hue due to Bragg reflection can also be changed. Covering the CLCs particles with polydimethylsiloxane results in the formation of a polymer dispersed liquid crystals–like structure, which enhances the structural color appearance and thermal stability of the CLCs particles. Additionally, a simple strategy to produce chiral anti‐counterfeiting QR codes is developed. By combining CLCs particles with commercially available pigments, an anti‐counterfeiting QR code that can only be displayed under a specific circular polarizer is created. This approach and resulting CLCs particles expand the modulation of CLCs structural color and enrich the application of structural color in the field of chiral optical anti‐counterfeiting.

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Dynamic control of colorful reflection toward practical cholesteric liquid crystal displays

Cited by 12 publications

References 22 publications

Manipulation of Structural Colors in Liquid-Crystal Helical Structures Deformed by Surface Controls

Manipulation of Structural Colors in Liquid-Crystal Helical Structures Deformed by Surface Controls

Control of Large-Area Orderliness of a 2D Supramolecular Chiral Microstructure by a 1D Interference Field

Particle Size Controlled Chiral Structural Color of Monodisperse Cholesteric Liquid Crystals Particles

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