The organic thin film transistor is a thin film transistor using an organic semiconductor material, and is superior in flexibility and lightness to conventional Si semiconductors. However, the value of field effect mobility is low due to poor thermal stability and molecular orientation. In this study, we synthesize a novel polymerizable liquid crystalline organic semiconductor molecule having a benzothieno[3,2-b][1]benzothiophene core and fabricate the organic thin film transistors with higher thermal stability and higher field effect mobility by the polymerization of the molecules in a liquid crystalline phase.

A photoreactive liquid crystal polymer composite was prepared from the monomer NBA carboxylic acid and side-chain photoinert benzoic acid polymethacrylate. The evaluation of the photo-alignment behavior and the fabrication of polarization holograms were performed using a thick film of polymer composite material. Mesophases have emerged in polymer composites due to the formation of hydrogen bonds between the monomer NBA carboxylic acid and the benzoic acid polymer. The Composite exhibit large optical anisotropy due to photoalignment followed by thermally-induced amplification. Furthermore, polarization holograms with a periodic structure exhibiting high diffraction efficiency were fabricated using polarization interference exposure of He-Cd laser beams.

We report the synthesis and characterization of a series of N-heteroacene derivatives. These compounds are composed of amphiphilic moieties, in particular, branched-alkyl chains-appended compound adopts a liquid state at room temperature. This compound shows fluorescent property with the green emission, of which color can be changed into the blue emission by heating.

Columnar liquid crystals with ferroelectricity are expected to be applied to high-density memory devices by controlling the polarization direction of each column with a nanoscale diameter. Recently, we reported that a diphenylurea derivative achieved a perfect ferroelectric columnar liquid crystal phase. However, due to the strong intracolumnar interaction, the ferroelectricity was observed only at high temperature (105-144°C), which is problematic when considering the application. In this study, we synthesized and characterized two novel amide compounds. As a result, one of them generated an electro-responsive columnar liquid crystal phase at room temperature.

Liquid crystals (LCs) have electro-optical properties of a large birefringence and dielectric anisotropy. The effective gradient-index distribution can be easily controlled by the LC molecular reorientation caused by axially symmetrical electric field. In this study, we propose an LC micro-prism array (LC-MPA) with two-divided and square-shaped electrodes for electrically varying a beam deflection angle without any mechanically moving parts. We investigate and discuss the optical performance of the LC-MPA in various applied voltages, and show its optical properties such as the optical phase distribution and the beam deflection.

Azo-polymer films can be induced bending motion by irradiation with UV or visible light. The azo-polymer films used as actuators are mainly studied experimentally, and numerical calculations have not been carried out so much. In this study, we calculate the film bending using smoothed particle hydromechanics method to analyze the mechanical properties.

Ferroelectric liquid crystals (FLC) is expected as next-generation liquid crystal display materials to show high speed response in comparison with nematic liquid crystals (NLC) used in a conventional display. the high fluidity that NLC has affects the properties of matter of FLC in mixture of FLC and NLC. A purpose of this study is to investigate the dependence of the NLC concentration and kind about properties of matter of the NLC and FLC mixture liquid crystals.

In this study, we aim to develop a novel liquid crystal display device with a waveguide structure to improve the performance of LCDs. To make the proposed waveguide cell more versatile, it is necessary to change the RGB color of the waveguide cell by using fluorescent materials as the excitation light source. In this paper, we report the difference of the performance between the green fluorescent material and the conventional waveguide cell.

We synthesized symmetric azobenzene-based dimers (CN)AzoSnSAzo(CN) (n = 3, 5, 7, 9 and 11) and asymmetric (CN)AzoSnSCB (n = 3, 5, 7, 9 and 11), and evaluated their phase-transition behavior using polarized light optical microscopy and differential scanning calorimetry. Symmetric (CN)AzoSnSAzo(CN) dimers exhibited higher phase-transition temperature than those of asymmetric (CN)AzoSnSCB dimers for corresponding n. Asymmetric (CN)AzoSnSCB (n = 7 and 9) exhibited the twist-bend nematic (NTB) phase across a wide temperature range. The NTB phases were supercooled to room temperature to be vitrified.

Control of molecular alignment in polymer films is of great importance to improve their surface functionality. Especially, surface structures of polymer films containing aligned liquid-crystalline molecules are changed owing to external stimuli, which is dependent on the patterned molecular alignment. In this study, we fabricated surface relief structures induced by novel molecular photoalignment process triggered by spatially selective photopolymerization and investigated the molecular alignment behavior in the obtained surface structures.

Cholesteric Liquid crystal elastomers (CLCE) have both orientation of liquid crystal and elasticity of polymer network. Especially, CLCE shows structural color and it changes with the helical pitch. In this study, we prepared CLCE by mixing multiple molecules with various functions. The synthesized materials showed structural color, and it changed as the external stress change. It also had different optical and mechanical properties depending on the inside molecular structure. From these results, it is possible to change the material properties easily, and such characteristics are expected to be applied as flexible devices.

In our group, we have been systematically studying siloxane-containing liquid crystalline compounds that form the bicontinuous cubic (Cub) liquid crystal phase. Very recently, we have focused on effects of molecular asymmetry and found that the Cub phase is maintained for a longer time when asymmetry is introduced into the core part of the molecule. In this study, we synthesized the novel siloxane-containing liquid crystalline compound with asymmetry introduced into the chain part of the molecule and investigated effect of asymmetry on the Cub phase formation.

The anchoring energy (W) plays an important role in the display principle of liquid crystal displays. By mixing the azo-dye into alignment films, we succeed in controlling W of the slippery interface under UV light illumination. W is derived from the director deformation of the interface when a magnetic field is applied.

We successfully fabricated the cholesteric liquid crystalline elastomer (CLCE) films of crosslinkable cellulose derivatives with visible Bragg reflection. Very recently, we have developed the flexible CLCE films with capabilities to reversibly control the reflection colors by not only compression, but also stretch process. In this presentation, we report on unique optical properties of the CLCE films upon uniaxial stretch process. Although our CLCE films selectively reflected the circularly polarized light with right-handedness at the initial state, the uniaxially stretched CLCE films showed the unique reflection characteristics of circularly polarized light with both right- and left-handedness.

In conventional photomobile polymer materials, aromatic rings such as azobenzene and phenyl benzoate have been used as mesogens. On the other hand, liquid crystal displays are composed of various liquid crystal molecules, and the characteristics change depending on their structures. Thus, we expected that photoresponsive behavior can be controlled by selecting molecular structures properly. In this study, we prepared two types of photomobile polymer materials with different side chains and evaluated their photoresponsive behavior at room temperature and 77 K (in liquid nitrogen).

In this study, we report compounds consisting of a branched alkoxy chain as well as three kinds of arylethynyl moieties at 2, 4, and 6-positions. Compounds substituted with benzenes and thiophenes show fluorescent properties, but does not show responsiveness to acid. On the other hand, the pyridine-introduced compound shows a change in fluorescence color upon the addition of HCl. This is because the added acid can interact with the imino-N atom to change the electronic state of compounds.

Although the construction of double-helix structures is an important challenge in supramolecular chemistry, no general construction method has been established for columnar liquid crystal phases. In this study, we have designed and synthesized a new urea molecule with an extended core and six chiral chains, and attempted to construct a double-helix structure in a columnar phase. In the columnar liquid crystal phase, the molecules were self-organized into a double-helix structure, according to the concept (anti-parallel dimerization → intermolecular hydrogen-bond network → chirality-induced helix formation).

Liquid crystals (LC), which have large anisotropy even in the terahertz region and excellent response to an external electric field, are expected to be applied to terahertz devices. On the other hand, nanofibers (NF) are known to be able to easily orient LC molecules because of their properties such as tiny diameter and large surface area per unit mass. By using NF/LC complex, a terahertz variable phase shifter can be realized. In this study, we clarify and evaluate the characteristics of the NRD waveguide type terahertz variable phase shifter using aligned NF/ nematic liquid crystal (NLC) complex.

Organic semiconductor using liquid crystallinity has possibility of deposition of flat and homogeneous thin-film. However, the research of patterning of liquid crystalline organic semiconductor has been hardly taken. Because of this, we used hydrophilic and hydrophobic patterns on substrates and deposition at liquid crystal phase temperature. We achieved flat and homogeneous patterning of organic semiconductor, and high mobility over 10 cm^2/Vs and low variation less than 20 % on characteristic of the transistor.

Organic semiconductor has various advantages compared to inorganic one. It's easy to manufacturing, has good toughness and lightness. However, practical use is difficult because of low mobility of career. Career moves through aromatic rings in organic compound. Therefore high molecular orientation order enhances mobility of organic semiconductor. We focus on organic semiconductor liquid crystal. We aim to make high mobility solid sample that has high uniform orientation, using control of molecular order by liquid crystal. We measure mobility of them by TOF(Time of Flight) measurement and evaluate.

When a voltage is applied to a nematic liquid crystal system, a dissipative structure, nematic electroconvection, is generated. In a planar aligned system, various convective patterns appear depending on the voltage. On the other hand, various studies on liquid crystal-polymer composite systems have been carried out to utilize the stabilizing effect of polymer networks on liquid crystal orientation. In this study, the polymer network is regarded as a porous medium, and the effects of the polymer network on the electroconvective structures are investigated.