Processing‐Driven Engineering of Transparent Conductive In‐Zn‐O Thin Films: A Comparative Study of Spin‐Coating, Inkjet Printing, and Screen Printing

ABSTRACT Transparent conductive oxides are essential materials for optoelectronic applications. However, achieving both high electrical conductivity and optical transparency with solution‐compatible deposition techniques remains challenging. In this work, In–Zn–O thin films are fabricated using three complementary solution‐based methods, spin coating, inkjet printing, and screen printing, with tailored solutions optimized for each technique. Although identical thermal treatments are applied, the deposition technique significantly affects film thickness, microstructure, and the resulting optical and electrical properties. All films are amorphous, with grain sizes ranging from a few nanometres to approximately 300 nm, depending on nucleation density controlled by solution concentration. After annealing in a reducing atmosphere, the films exhibit low electrical resistivity (1–100 mΩ cm), high optical transparency (>90% in the visible–NIR range), and direct bandgaps of 3.3–3.6 eV. Spectroscopic ellipsometry indicates uniform optical properties for printed films, while spin‐coated films show slight inhomogeneity linked to their layered microstructure. These results clarify the interplay between solution chemistry, deposition method, and drying conditions in tuning the optoelectronic performance of In–Zn–O thin films. This study presents the first demonstration of conductive and transparent In–Zn–O thin films produced by screen printing.