Enhancement of Contrast Ratio by Using Ferroelectric Nanoparticles in the Alignment Layer of Liquid Crystal Display

Kundu, Sudarshan; Akimoto, Mitsuhiro; Hirayama, Itaru; Inoue, Masaru; Kobayashi, Shunsuke; Takatoh, Kohki

doi:10.1143/jjap.47.4751

Cited by 25 publications

(7 citation statements)

References 5 publications

(5 reference statements)

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“…To our knowledge, three types of ferroelectric materials have been studied as dopants of nanoparticles in LC matrixes: Sn 2 P 2 S 6 [3,7,8,[14][15][16], BaTiO 3 [6,7,17] and ZnO [9]. Since the majority of the experimental data were collected for the material Sn 2 P 2 S 6 (tin thiohypodiphosphate) and the nano-colloids based on this are extremely promising for photorefractive applications [14,15,18], this ferroelectric material was chosen for our experiments.…”

Section: Methodsmentioning

confidence: 99%

Nano-colloids of Sn_{2}P_{2}S_{6} in nematic liquid crystal pentyl-cianobiphenile

Kurochkin¹,

Atkuri²,

Buchnev³

et al. 2010

Condens. Matter Phys.

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It has been shown experimentally that the ferroelectric nano-particles, in common with other molecular additives, shift the clearing temperature, Tc, extending or reducing the two-phase coexistent region and changing the average order parameter of the single-component nematics. An increase of up to 11 • C or a smaller decrease of as much as 3 • C of Tc, and corresponding changes of the order parameter were observed. In all cases the order parameter of the colloid followed the universal temperature behaviour, which is a characteristic of LCs with molecular additives.

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Section: Methodsmentioning

confidence: 99%

Nano-colloids of Sn_{2}P_{2}S_{6} in nematic liquid crystal pentyl-cianobiphenile

Kurochkin¹,

Atkuri²,

Buchnev³

et al. 2010

Condens. Matter Phys.

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“…Concurrently, recent years have also seen a tremendous increase in the number of reports describing the use of nanoparticles (NPs) dispersed in LCs (NP-doped LCs or LC/NP composites) to yield macroscopic alignment of LCs, and in some instances, the alignment altered or induced by the NPs comes jointly with the manipulation of other LC properties or LCD-relevant characteristics, such as threshold voltage, pretilt, dielectric behavior, or contrast ratio ,− . The most prominent among these nanoparticulate systems are oligomeric silsesquioxanes NPs with size from 0.7−30 Å inducing vertical alignment , , carbon nanotubes − , fullerenes , and gold nanoparticles (Au NPs) developed by our group ,,− .…”

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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“…The achievement in uniformity pertaining to the polymer alignment layer of a large-sized panel display designed for over 2 m 2 in size for Gen8 LCD fabrication lines is also demanding and challenging. Recently, polyhedral oligomeric silsesquioxane (POSS) [14][15][16][17][18][19][20][21][22] nanoparticles dispersed in LC show uniform vertical alignment without the need for any further aligner on the substrates. However, to achieve multi-domain vertical alignment using POSS with high image quality in all viewing directions has not been proposed.…”

Section: Introductionmentioning

confidence: 99%

Polymer‐stabilized pretilt angle on the surface of nanoparticle‐induced vertical‐alignment surface for multi‐domain vertical‐alignment liquid‐crystal display

et al. 2011

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Abstract— By introducing polyhedral oligomeric silsesquioxane (POSS) nanoparticles along with a controlled amount of UV‐curable reactive mesogen (RM) into a liquid‐crystalline (LC) medium, a multi‐domain vertical‐alignment LC device was successfully demonstrated. The device, possessing a vertically aligned LC director in four different azimuthal directions, exhibited a fast response time and wide‐viewing‐angle characteristics, in the absence of conventional polymer‐type vertical‐alignment layers. Electro‐optic characteristics of the fabricated device, before and after UV curing of the cell, were studied. The surface morphology of the substrate surfaces were analyzed by using field‐emission scanning electron microscopy (FESEM). The experimental results show that the technology will possibly be applicable to cost‐effective vertical‐alignment liquid‐crystal devices and is suitable for green‐technology liquid‐crystal displays.

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Enhancement of Contrast Ratio by Using Ferroelectric Nanoparticles in the Alignment Layer of Liquid Crystal Display

Cited by 25 publications

References 5 publications

Nano-colloids of Sn_{2}P_{2}S_{6} in nematic liquid crystal pentyl-cianobiphenile

Nano-colloids of Sn_{2}P_{2}S_{6} in nematic liquid crystal pentyl-cianobiphenile

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

Polymer‐stabilized pretilt angle on the surface of nanoparticle‐induced vertical‐alignment surface for multi‐domain vertical‐alignment liquid‐crystal display

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