Liquid crystal elastomers (LCEs) are unique materials with the strong coupling of molecular orientation and macroscopic shape. The LCE films with hybrid alignment (HNE), where the director configuration continuously changes from planar to vertical alignment along the thickness direction, show thermally induced large bending deformation as a result of a change in the degree of local nematic order. We investigate the bending deformation accompanying volume phase transition for the HNE films swollen in isotropic and nematic solvents.

The structure of liquid crystal blue phases doped with dichroic dyes was observed by confocal laser scanning microscope using polarizing excitation light with controllable polarization plane. Depending on the polarization plane, different patterns with periods of sub-micrometer were observed. The spatial periods in the images at fluorescent mode using dichroic dye were found to be half of those in images at conventional reflection mode. It is expected that the contrast of light and shade in the fluorescence images reflects distribution of direction of the directors in the blue phase lattice.

Summary: The smectic liquid crystal (LC) arrangements of binary mixtures of rod-like polymers, i.e., poly[n-decyl-(S)-2-methylbutylsilane], with different molecular weights and narrow molecular weight distributions, were investigated by synchrotron radiation small-angle X-ray scattering (SR-SAXS) and atomic force microscopy (AFM) analyses. According to the theoretical predictions based on the computer simulations, binary mixtures of long and short rod-like particles show the phase separation when the length ratio of two components is greater than 5. In this study, we show that this theoretical prediction is almost quantitatively reproduced: two identical polymers, whose only difference is molecular weight, segregates into each component merely by an entropic driving force.

The liquid crystal compound having 1, 3-dioxane unit in the mesogenic core (DIO, JNC Co.) shows anomalously high dielectric permittivity and second harmonic generation (SHG) activity in a certain temperature range. We speculate that the high dielectric permittivity results from generation of local clusters of the molecules of which dipole moment along the molecular long axis orientats unidirectionally like ferroelectrics. However, the detail of the mechanism is unclear. In this study, we investigated concentration dependence of physical characteristics of DIO. As a result, both dielectric permittivity parallel to the director and SHG intensity decreased drastically by diluting DIO with other normal nematic liquid crystals. This results clearly shows that the local ferroelectric-like orientation of DIO disappeared rapidly by dilution, suggesting that a special short-range intermolecular interaction could be responsible forthe ferroelectric-like orientation.

Thermal phase transitions and carrier transport properties in binary mixtures of a liquid crystalline phthalocyanine, 1,4,8,11,15,18,22,25-octahexyl-phthalocyanine (C6PcH2) and its analogue, 1,4,8,11,15,18,22,25-octahexyl-tetrabenzotriazaporphyrin (C6TBTAPH2), have been studied. In order to clarify the miscibility and crystal structure of the binary mixtures, the phase diagram was investigated by using DSC, and the XRD analysis was carried out. The high hole mobility was estimated by time-of-flight technique, and the blend ratio dependence of the hole mobility was discussed by taking the dominant molecular packing structure in the binary mixture into consideration.

We have fabricated arrays of organic field-effect transistors (OFETs) with an active layer of poly(2,5-bis(3-hexadecylthiophen-2-yl)thieno[3,2-b]thiophene (pBTTT-C16), and evaluated the device-to-device variation of the OFET properties. The pBTTT-C16 active layer was formed by a flow-coating method, which has a potential capability of aligning polymer backbone structure along the flow-coating direction. The device-to-device variation was evaluated for each set of the parallel and perpendicular OFETs, where the “parallel (perpendicular)” indicates the channel current direction with respect to the flow-coating direction. The OFET array showed a very small device-to-device variation, indicating high spatial uniformity of flow-coated pBTTT-C16 films in charge transport.

Control of molecular orientation in single crystalline films is one of challenges for printed organic thin film transistors for flexible liquid crystal displays. To overcome this issue, we focused on directional control of single crystalline films using liquid crystal solvent. Previously, we achieved fabrication of single crystalline films based on benzothienobenzothiophene derivatives (C8BTBT). However, their crystal structure is not cleared. In this study, we discuss the relationship between aligned liquid crystal and analyzed their single crystalline structure. As the results, we clarified that direction of crystalline b-axis is aligned to rubbing-treated direction due to parallel-aligned liquid crystals.

Recently, great interest has been paid for organic thin film devices which exhibit superior processability and flexibility. We have already reported π-conjugated ferroelectric LC phenylterthiophene derivatives exhibiting the anomalous photovoltaic effect. In this study, we synthesized the phenylterthiophene derivative bearing a polymerizable cyclotetrasiloxane ring at the terminal position of the alkyl side chain in order to improve the conversion efficiency by the stabilization of spontaneous polarization. The mesomorphic property, ferroelectricity, and carrier transport characteristics of the LC compounds were characterized. Moreover, in situ polymerization　and anomalous photovoltaic effect will be reported.