Ionic Liquid Crystal-Based Soft Template Approach for Synthesizing ZnO Nanostructures and Their Applications in Thin-Film Transistors

Nanostructured semiconducting materials play a crucial part in the miniaturization of consumer electronics. The electronic and optical properties of nanomaterials are heavily dependent on their size and morphology. Their functional properties can be tuned to extract better device performances by modifying the synthetic protocols. Here, a soft template approach utilizing the liquid crystalline phase of an ionic liquid crystal derived from 3-pentadecylphenol, a major byproduct from the cashew industry, is employed to generate hexagonal ZnO nanostructures (ZnO_q). The evaluation of the optoelectronic properties of ZnO_q reveals that it harbors defect states, i.e., Zn and oxygen vacancies in the crystalline lattice, which are responsible for the improved conducting behavior. The electronic mobility of ZnO_q was evaluated by fabricating bottom-gate thin-film transistors with the configuration Si /SiO₂/ZnO_q/Ag. The field-effect mobility of ZnO_q estimated from the transfer characteristics was 8.9 ± 0.15 cm²/V s with an ON/OFF ratio of 10⁸ at a drain-source voltage of 3 V. The development of nanomaterials with superior carrier mobilities utilizing an industrial waste byproduct-derived soft material is a perfect example of a trash-to-treasure strategy.