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.