Impact of Ion Doping on the Dielectric and Electro-Optical Characteristics of Chiral Nematic Liquid Crystals

Yu-Kai Chang¹, I-Tseng Lin^2*, Wei Lee¹

¹Imaging and Biomedical Photonics, National Yang Ming Chiao Tung University, Tainan, Taiwan
²Institute of Photonic System, National Yang Ming Chiao Tung University, Tainan, Taiwan

* Presenter:I-Tseng Lin, email:eva5971555@gmail.com

In this study, we investigated the dielectric and conductive properties of a cholesteric liquid crystal (CLC) mixture incorporated with the cationic surfactant cetyltrimethylammonium bromide (CTAB), focusing on conditions that induce electrohydrodynamic effects. Our experiments demonstrated that by incorporating ions into CLC with CTAB concentration of 0.01-0.2 wt.%, the uniform lying helix (ULH) state appears. By analyzing dielectric spectra across specific frequency ranges, we calculated the physical properties, including DC conductivity, ion density, and diffusion coefficient, all of which were found to be significantly influenced by CTAB concentration and temperature. Multiple phase properties in this system can be applied in electro-optical devices, light-intensity modulators, and smart windows.

Keywords: Cetyltrimethylammonium Bromide (CTAB), Ionic Surfactant, Cholesteric Liquid Crystal, Electrohydrodynamic Effect, Dielectric Spectroscopy