ENGINEERING COLLOIDAL ITO AND CORE-SHELL NANOSTRUCTURES: A SCALABLE APPROACH FOR TRANSPARENT AND CONDUCTIVE FILMS

This thesis presents a comprehensive study on the synthesis, scale-up and electrical characterization of colloidal indium tin oxide (ITO) nanocrystals (NCs) and their core-shell structures for optoelectronic nanodevices. Transparent conductive oxides (TCOs), especially ITO, are essential in optoelectronic applications due to their unique combination of electrical conductivity and optical transparency. However, challenges such as cost, scarcity, and processing limitations necessitate innovative approaches. The research introduces and optimizes a continuous growth injection synthesis method to produce high-quality ITO NCs and ITO/In₂O₃ core-shell nanocrystals with controlled particle size, doping levels, and reproducible structural properties. Advanced characterization techniques, including UV-Vis-NIR spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), and inductively coupled plasma-optical emission spectroscopy (ICP-OES), provided critical insights into the optical, structural, and compositional characteristics, significantly improving the understanding of correlations between synthesis conditions, morphology, and material performance. The thesis further investigates thin film fabrication methods, focusing particularly on solution-based deposition processes such as spin-coating. It systematically evaluates the impact of critical factors such as ligand removal, colloidal stability, film thickness, and annealing conditions on the electrical conductivity and optical transparency of the films. Electrical characterization using four-point probe measurements highlights substantial improvements in conductivity achieved through optimized processing protocols, establishing clear guidelines for enhancing TCO film performance. This work significantly advances the practical application potential of colloidal TCO nanomaterials, offering scalable, cost-effective, and environmentally sustainable alternatives to conventional ITO-based technologies. The results provide a robust foundation for future research and industrial implementations in flexible electronics, photovoltaics, sensors, and advanced optoelectronic devices.