Inverse Helical Nanofilament Networks Serving as a Chiral Nanotemplate.

Herein, an epoch-making method based on bottom-up templating is proposed for the fabrication of a chiral nanoporous film that provides a chiral environment in which to confine nematic liquid crystals. A helical nanofilamental network of bent-core molecules was utilized as a three-dimensional mold, and thus the fabricated chiral nanoporous film has an inverse nanohelical structure. The presence of a chiral superstructure was confirmed by the observation of circular dichroism signals. Upon refilling this chiral nanoporous film with an achiral nematic liquid crystal, distinct circular dichroism signals appeared due to the transfer of chirality from the inverse helical nanofilaments to the achiral nematic liquid crystal. The circular dichroism signals can be readily modulated by external stimuli, such as the application of heat or an electric field. In addition, by refilling the chiral nanoporous film with a nematic liquid crystal doped with fluorescent dye, it exhibits stimuli-responsive circularly polarized luminescence. The proposed approach has huge potential for practical applications, such as for chiroptical modulators and switches and biological sensors.

Micro-Segregated Liquid Crystal Haze Films for Photovoltaic Applications: A Novel Strategy to Fabricate Haze Films Employing Liquid Crystal Technology.

Herein, a novel strategy to fabricate haze films employing liquid crystal (LC) technology for photovoltaic (PV) applications is reported. We fabricated a high optical haze film composed of low-molecular LCs and polymer and applied the film to improve the energy conversion efficiency of PV module. The technique utilized to fabricate our haze film is based on spontaneous polymerization-induced phase separation between LCs and polymers. With optimized fabrication conditions, the haze film exhibited an optical haze value over 95% at 550 nm. By simply attaching our haze film onto the front surface of a silicon-based PV module, an overall average enhancement of 2.8% in power conversion efficiency was achieved in comparison with a PV module without our haze film.

Effect of terminal chain length on the helical twisting power in achiral bent-core molecules doped in a cholesteric liquid crystal.

We prepared a homologous series of achiral bent-core (BC) liquid crystals with different terminal alkoxy chain lengths, n (BC-n), and evaluated the helical twisting power (HTP) of the BC-n doped in a cholesteric liquid crystal. The BC-n molecules with longer terminal chains showed larger HTPs. To interpret this striking phenomenon, a stochastic dynamics simulation was performed to determine the distribution of the chirality order parameters (χ) for BC molecules with n = 8-16. The distribution of χ for each simulated conformation varied with n, and the variation tendency was different for molecules with n < 12 and n > 12 despite the linear relationship between HTP and n in the experiment.

Polymer Stabilization of Liquid-Crystal Blue Phase II toward Photonic Crystals.

The temperature ranges where a pure simple-cubic blue phase (BPII) emerges are quite narrow compared to the body-centered-cubic BP (BPI) such that the polymer stabilization of BPII is much more difficult. Hence, a polymer-stabilized BPII possessing a wide temperature range has been scarcely reported. Here, we fabricate a polymer-stabilized BPII over a temperature range of 50 °C including room temperature. The fabricated polymer-stabilized BPII is confirmed via polarized optical microscopy, Bragg reflection, and Kossel diagram observations. Furthermore, we demonstrate reflective BP liquid-crystal devices utilizing the reflectance-voltage performance as a potential application of the polymer-stabilized BPII. Our work demonstrates the possibility of practical application of the polymer-stabilized BPII to photonic crystals.