Special Issue "Liquid Crystal Films"

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A special issue of Crystals (ISSN 2073-4352).

Deadline for manuscript submissions: closed (31 July 2015)

Special Issue Editor

Guest Editor
Dr. Hiroyuki Yoshida

Division of Electrical, Electronic and Informational Engineering, Osaka University Yamada-oka, Suita-shi, Osaka-fu, 565-0871 Japan
Phone: +81-6-6879-7759

Special Issue Information

Dear Colleagues,

The liquid crystal state of matter is one in which molecules possess orientational order while no positional order is present. Films made from liquid crystals form a family of functional materials with great potential in various technological fields, from optics to mechanics to electronics to biological sciences. Electro-tunable birefringence in nematic liquid crystals caused by voltages as low as few volts forms the basis of flat panel displays; today, new liquid crystal phases and materials, such as blue phases and polymer or nanoparticle composites and are being actively pursued for better electro-optic performance. Following the recent advances in nanofabrication techniques, liquid crystals have been combined with photonic crystals and metamaterials to provide tunability in these devices. On the other hand, using the ability of liquid crystal molecules to self-organize into complex three-dimensional structures, polymer and elastomeric films with properties not easily attainable by man-made structures, such as tunable, circular Bragg reflection and lasing have been realized. Semiconducting liquid crystals forming smectic or columnar phases have proven their potential for high-performance photovoltaics (OPVs) and transistors (OFETs).

Liquid crystal science is an interdisciplinary area of science which calls for collaboration of physicists, chemists, biologists, and engineers.

This special issue welcomes research articles on the fabrication, characterization and application of functional liquid crystalline films.

Dr. Hiroyuki Yoshida
Guest Editor

Submission

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. Papers will be published continuously (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are refereed through a peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Crystals is an international peer-reviewed Open Access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 800 CHF (Swiss Francs).

Keywords

  • liquid crystals
  • liquid crystal-polymer nanocomposites
  • liquid crystal-nanoparticle composites
  • photonic crystals
  • metamaterials
  • photovoltaics
  • electro-optics
  • tunable films

Published Papers (4 papers)

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Research

Open AccessArticle Electrically Rotatable Polarizer Using One-Dimensional Photonic Crystal with a Nematic Liquid Crystal Defect Layer
Crystals 2015, 5(3), 394-404; doi:10.3390/cryst5030394
Received: 31 July 2015 / Revised: 4 September 2015 / Accepted: 10 September 2015 / Published: 14 September 2015
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Abstract
Polarization characteristics of defect mode peaks in a one-dimensional (1D) photonic crystal (PC) with a nematic liquid crystal (NLC) defect layer have been investigated. Two different polarized defect modes are observed in a stop band. One group of defect modes is polarized [...] Read more.
Polarization characteristics of defect mode peaks in a one-dimensional (1D) photonic crystal (PC) with a nematic liquid crystal (NLC) defect layer have been investigated. Two different polarized defect modes are observed in a stop band. One group of defect modes is polarized along the long molecular axis of the NLC, whereas another group is polarized along its short axis. Polarizations of the defect modes can be tuned by field-induced in-plane reorientation of the NLC in the defect layer. The polarization properties of the 1D PC with the NLC defect layer is also investigated by the finite difference time domain (FDTD) simulation. Full article
(This article belongs to the Special Issue Liquid Crystal Films)
Open AccessArticle Pitch-Length Independent Threshold Voltage of Polymer/Cholesteric Liquid Crystal Nano-Composites
Crystals 2015, 5(3), 302-311; doi:10.3390/cryst5030302
Received: 3 July 2015 / Revised: 7 August 2015 / Accepted: 13 August 2015 / Published: 19 August 2015
Cited by 1 | PDF Full-text (3721 KB) | HTML Full-text | XML Full-text
Abstract
Polymer/cholesteric liquid crystal (ChLC) nano-composites consisting of mesogenic monomers and LCs have nano-sized LC domains dispersed in an anisotropic polymer matrix. They exhibit characteristics not observed in conventional ChLCs, such as sub-millisecond and “deformation-free” electro-optic tuning of the selective reflection band; however, [...] Read more.
Polymer/cholesteric liquid crystal (ChLC) nano-composites consisting of mesogenic monomers and LCs have nano-sized LC domains dispersed in an anisotropic polymer matrix. They exhibit characteristics not observed in conventional ChLCs, such as sub-millisecond and “deformation-free” electro-optic tuning of the selective reflection band; however, their driving voltage is high compared to conventional ChLCs, and is an issue that needs to be solved for the practical use. Here, we investigate the helical pitch dependence of threshold voltage in polymer/ChLC nano-composites. Five samples with different helical pitches were prepared and their electro-optic characteristics were compared before and after photopolymerization. Although the threshold voltage of the unpolymerized samples were inversely proportional to its helical pitch, the threshold voltage of the polymerized samples showed no dependence on the helical pitch. These results are explained to be a consequence of the driving mechanism of the polymer/ChLC nano-composite, in which electro-optic switching is achieved as a consequence of the nano-confined LC molecules reorienting along the electric field, instead of the helical structure becoming unwound. The threshold voltage is independent of pitch length because the pore sizes are similar in all samples. Full article
(This article belongs to the Special Issue Liquid Crystal Films)
Open AccessArticle Ferronematics Based on Paramagnetic Nitroxide Radical Liquid Crystal
Crystals 2015, 5(2), 206-214; doi:10.3390/cryst5020206
Received: 23 March 2015 / Revised: 16 April 2015 / Accepted: 20 April 2015 / Published: 27 April 2015
Cited by 2 | PDF Full-text (715 KB) | HTML Full-text | XML Full-text
Abstract
We have prepared novel ferronematics based on a paramagnetic liquid crystalline (LC) material. Our ferronematics can disperse a higher volume fraction of magnetic nanoparticles compared to classical ferronematics because paramagnetic nature of the host LC material prevents the aggregation of magnetic nanoparticles. [...] Read more.
We have prepared novel ferronematics based on a paramagnetic liquid crystalline (LC) material. Our ferronematics can disperse a higher volume fraction of magnetic nanoparticles compared to classical ferronematics because paramagnetic nature of the host LC material prevents the aggregation of magnetic nanoparticles. The interactions between the magnetic nanoparticles and the LC material enhance a magnetic anisotropy of ferronematics and improve the magnetic responsivity. Full article
(This article belongs to the Special Issue Liquid Crystal Films)
Open AccessArticle Infrared Extinction of a Dye-Doped (Polymer/Liquid Crystal) Composite Film
Crystals 2015, 5(1), 163-171; doi:10.3390/cryst5010163
Received: 16 January 2015 / Revised: 28 January 2015 / Accepted: 4 February 2015 / Published: 2 March 2015
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Abstract
Infrared extinction of a dye-doped (polymer/liquid crystal) composite film was investigated. It is found that doping a metal-complex dye into the liquid crystal extended the operation wavelength to an optical fiber communication wavelength of about 1.5 μm. An aperture placed behind the [...] Read more.
Infrared extinction of a dye-doped (polymer/liquid crystal) composite film was investigated. It is found that doping a metal-complex dye into the liquid crystal extended the operation wavelength to an optical fiber communication wavelength of about 1.5 μm. An aperture placed behind the composite film greatly improves an extinction ratio, which suggests the film functions on the basis of light scattering. Some experimental results agree to Rayleigh scattering. The film exhibits the high extinction ratio of 51 or 17.1 dB and a low polarization dependent loss of 7.6% or 0.32 dB and, then, it could be applied to a telecommunication device such as a variable optical attenuator. Full article
(This article belongs to the Special Issue Liquid Crystal Films)

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