Electroactive liquid crystal monomer based on cholesterol and carbazole: Synthesis, characterization, and electrochromic properties of the thin film

Liquid crystals are widely used in display technologies, tunable photonic devices, and sensors owing to their anisotropic optical properties and responsiveness to external stimuli such as electric and magnetic fields. In recent years, the intersection of liquid crystals and conductive polymers has yielded fascinating insights into new materials with potential applications in optoelectronics, sensors, and energy-storage systems. In this paper, we report the synthesis and characterization of B1 monomers containing cholesterol and carbazole moieties, thus enabling liquid crystal properties and electroactivity. The phase transitions and optical textures of the B1 monomer were analysed using polarised optical microscopy (POM) and Differential Scanning Calorimetry (DSC). Also, B1 monomer showed typical aggregation-induced emission enhancement (AIEE) properties with variable aggregative state emission in THF-water mixture. The electroactive monomer was electropolymerized to form a stable film on a conductive substrate. The resulting polycarbazole-based thin film displayed reversible electrochromic behaviour between transparent and greenish blue, with an optical contrast of 43 %. In addition, the morphological properties of the polycarbazole-based thin films were analysed by atomic force microscopy (AFM) and Scanning Electron Microscopy (SEM). These findings provide a solid foundation for the development of highperformance electrochromic devices and other smart material applications.