Plasma‐beam alignment technique for ferroelectric liquid crystals

Hegde, Gurumurthy; Yaroshchuk, O.; Kravchuk, R.; Murauski, Anatoli; Chigrinov, Vladimir G.; Kwok, Hoi‐Sing

doi:10.1889/jsid16.10.1075

Cited by 7 publications

(4 citation statements)

References 21 publications

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“…One prominent technique, extensively utilized by Abbott et al ,− , makes use of alkylthiol self-assembled monolayers (SAMs) either on thin gold films sputtered on glass or gold islands (i.e., nanoparticles) immobilized on surfaces via electron beam evaporation, which, depending on the chain length, combination of chain lengths, and functionalization, can induce multiple alignment scenarios in nematic LCs , . Another technique employs either glancing angle ion-beam deposition , , as well as ion beam ,− or plasma bombardment − of thin polymer, SiN x , diamond-like carbon, or other thin films deposited on substrates. Of these techniques, the glancing angle ion beam bombardment of diamond-like carbon is already used for the manufacturing of smaller LCD panels by IBM , .…”

Section: Introductionmentioning

confidence: 99%

Multiple Alignment Modes for Nematic Liquid Crystals Doped with Alkylthiol-Capped Gold Nanoparticles

Hegmann

2009

ACS Appl. Mater. Interfaces

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The ability of alkylthiol capped gold nanoparticles (Au NPs) to tune, alter, and reverse the alignment of nematic liquid crystals (LCs) has been investigated in detail. Adjusting the concentration of the suspended Au NPs in the nematic LC host, optimizing the sample preparation protocol, or providing different sample substrates (untreated glass slides, rubbed polyimide-coated LC test cell, or ITO-coated glass slides) results in several LC alignment scenarios (modes) including vertical alignment, planar alignment, and a thermally controlled alignment switch between these two alignment modes. The latter thermal switch between planar and homeotropic alignment was observed particularly for lower concentrations (i.e., around 1 to 2 wt %) of suspended NPs in the size regime of 1.5-2 nm and was found to be concentration-dependent and thermally reversible. Different scenarios are discussed that could explain these induced alignment modes. In one scenario, the NP-induced alignment is related to the temperature-dependent change of the order parameter, S, of the nematic phase (ordering in the bulk). In the second scenario, a change of the ordering of the nematic molecules around the NPs that reside at the interfaces is described. We also started to test spin coating as an alternative way of preparing nematic thin films with well-separated Au NPs on the substrate and found this to be a possible method for manufacturing of future NP-doped LC devices, as this method produced evenly distributed NPs on glass substrates. Together the presented findings continue to pave the way for LC display-related applications of Au NP-doped nematic LCs and provide insights for N-LC sensor applications.

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Section: Introductionmentioning

confidence: 99%

Multiple Alignment Modes for Nematic Liquid Crystals Doped with Alkylthiol-Capped Gold Nanoparticles

Hegmann

2009

ACS Appl. Mater. Interfaces

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“…The polar anchoring energy of rubbed polyimide (PIA-X201-G01, Chisso) was measured to be within the order of 10 -4 -10 -3 J/m 2 , and the plasmatreated PI surfaces were measured to be within the order of 10 -5 J/m 2 . 16,17 The surface polarities of alignment layers were determined by the cross-rubbed cell. 18 Polyimide as the negative-surface-polarity material was applied.…”

Section: Methodsmentioning

confidence: 99%

Defect‐free half‐V‐mode ferroelectric liquid‐crystal device

Lin

Chen

2010

J Soc Info Display

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Abstract— The horizontal chevron defect found in a half‐V‐mode ferroelectric‐liquid‐crystal (HV‐FLC) device can be suppressed by lowering the FLC's total free energy. The energy levels between spontaneous polarization (PS) up and down domains were degenerated by asymmetrical‐alignment treatments. The difference in the polar surface coefficient (γ2) was the key to suppressing the alignment defect. Alignment layers with opposite surface polarities and different anchoring energies were applied to control the sign and value of γ2. The asymmetric cells of PIrub ‐ PIplasma (rubbed polyimide and plasma‐treated polyimide surfaces), PVArub ‐ PIplasma (rubbed polyvinyl alcohol and plasma‐treated polyimide surfaces), and PVArub ‐ PIplasma (both rubbed PI and PVA) alignment conditions presented defect‐free alignment textures under a slow‐cooling process. Among these different alignment treatments, the PVArub ‐ PIrub treated cell demonstrated the best alignment result, benefited by the largest difference in polar surface coefficient.

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“…Thus, there is an urgent need for such an alignment process, which can combine the advantages of rubbed and non-rubbed aligning layers. In present study this is achieved by using plasma beam (PB) alignment technique earlier adopted for nematic [2,3] and ferroelectric [4] thermotropic LCs, reactive mesogens [5], and lyotropic chromonic LCs [6]. Good potential of this technique for alignment patterning and formation of uniform and stable ULH textures of CLC is also demonstrated.…”

Section: Introductionmentioning

confidence: 92%

P.99: Alignment Peculiarities of Cholesteric Liquid Crystals on the Surfaces Processed by Plasma Beam

Kravchuk

Yaroshchuk

2013

Symp Digest of Tech Papers

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It is demonstrated that plasma beam alignment process allows one to combine uniformity of planar texture and stability of focal conic texture of cholesteric liquid crystals (CLC) and thus obtain highly contrast and truly bistable samples. It provides suitable anchoring conditions for ULH texture. It can also be readily applied for the alignment patterning that opens new prospects for CLC devices. Author Keywordsliquid crystal alignment; ion beam alignment; plasma beam alignment; cholesteric liquid crystal; reflective display, ULH texture.

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Plasma‐beam alignment technique for ferroelectric liquid crystals

Cited by 7 publications

References 21 publications

Multiple Alignment Modes for Nematic Liquid Crystals Doped with Alkylthiol-Capped Gold Nanoparticles

Multiple Alignment Modes for Nematic Liquid Crystals Doped with Alkylthiol-Capped Gold Nanoparticles

Defect‐free half‐V‐mode ferroelectric liquid‐crystal device

P.99: Alignment Peculiarities of Cholesteric Liquid Crystals on the Surfaces Processed by Plasma Beam

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