Helical Columnar Liquid Crystal Exhibiting Both Polarization Retention and Ferroelectric Switching at Room Temperature

Abstract

Ferroelectric columnar liquid crystals (FCLCs) with switchable bistable axial polarizations are promising candidates for high-density ferroelectric random-access memory (FeRAM). However, FCLCs simultaneously exhibiting uniform polarization arrangement and ferroelectric switching at room temperature (RT) remain elusive. Herein, we report an RT-operable FCLC based on C3-symmetric star-shaped mesogen with polar linkers. Two CLCs, 1 and 2, were synthesized incorporating 1,2,3-triazole and amide linkers, respectively. 1 undergoes a ferroelectric-to-paraelectric transition accompanied by a structural change from helical to a nonhelical columnar phase. Notably, the ferroelectric switching is operable down to RT, with complete retention of its axial macrodipole after removal of the electric field. In contrast, 2 forms only a nonhelical columnar LC phase, displaying paraelectric behavior. The contrasting self-assembly and dielectric properties are attributed to the differences in the polar unit size. This study demonstrates that the mesogen extension with a bulky 1,2,3-triazole linker enables the realization of an FCLC operable at RT, offering significant potential for high-density FeRAM applications.