Interdigitated Self-Assembly and Quasi 2D-Charge Transport Behavior of Sterol-Based Ionic Liquid Crystalline Material

Mesogenic ionic liquids hold great promise for developing efficient ion-conductive materials due to their structural organization and anisotropic nature, which involve ions as charge carriers. In this study, we present the synthesis and characterization of a smectogenic, cholesterol-containing, imidazolium-based ionic liquid crystal (ILC). The liquid crystallinity of the compound was examined through polarized optical microscopy (POM), differential scanning calorimetry (DSC), and X-ray diffraction (XRD) techniques. The synthesized ionic smectogen displayed a broad enantiotropic smectic A (SmA) mesophase with a low clearing temperature, excellent thermal stability, and spontaneous homeotropic alignment on an untreated glass plate. Furthermore, the ILC exhibits 2D charge transport via a thermally activated hopping process, resulting in excellent hole mobility in the order of 10^-2 cm²V^-1s^-1 as determined by the space-charge limited current (SCLC) technique by decanting the effect of traps. Such a high charge carrier mobility is very rare for the SmA mesophase. Dielectric spectroscopy of the ILC depicts the existence of a single relaxation mode analogous to the Cole-Cole type molecular relaxation with an exceptionally high value of relative permittivity in the range of 500-2000 at 100 Hz. Such ILCs indicate their potential use in highly efficient supercapacitors, photovoltaic solar cells, dielectric resonators, sensors, actuators, etc.