Stabilization and optical switching of liquid crystal blue phase doped with azobenzene-based bent-shaped hydrogen-bonded assemblies

Abstract

We develop a new kind of bent-shaped hydrogen-bonded assemblies (H-bonded assemblies) to stabilize liquid crystal blue phases (LC-BPs) and optically switch the Bragg reflection band of BPs. Here the H-bonded assemblies are simply assembled with the proton acceptor containing azobenzene mesomorphic group and diacid proton donors. The BPs temperature ranges of the LC samples are significantly widened by H-bonded assembly dopants, and the widest BP temperature range is 16.7 °C. Moreover, the lower temperature of BPs is very close to room temperature. Additionally, a blue-shift of the Bragg reflection bands with the corresponding reflection color from green to blue is observed in the LC sample doped with H-bonded assemblies upon UV light irradiation. The related physics mechanisms for the stabilization and optical switching of BPs may be contributing to the bent-shaped molecular geometry of H-bonded assemblies and photoisomerization of azobenzene moiety in H-bonded assemblies, respectively. This work opens up a way to design self-organized molecules suitable for optically tuning BP display and other photonic devices.