Stable precursor-ink strategy for inkjet-printed high-temperature oxide films: Towards scalable ITO/In₂O₃ fabrication

Inkjet printing presents a promising route for the scalable, high-resolution, and low-cost fabrication of functional oxide thin films; however, the design of robust inks capable of producing uniform, stable, and high-temperature-resistant oxide films remains highly challenging. Here, a highly stable precursor-based ink system for inkjet printing of ITO/In₂O₃ thin films is developed. By precisely tuning the mixed solvent ratio (EG:2-ME) and additive (EC) concentration, the rheological properties, jetting stability, and film uniformity are synergistically optimized, effectively suppressing the coffee-ring effect and improving surface morphology and structural density. The developed ink demonstrates good long-term storage stability and reproducibility, maintaining consistent chemical composition, particle size distribution, and thin-film performance over multiple batches and prolonged storage (120 days). Flexible thermoelectric films printed with this ink show reliable stability and repeatability of thermoelectric response over a broad temperature range (−196 to 848 °C), stable operation up to 100 h and under 50 thermal cycles at 800 °C. This work provides a reliable, scalable, and broadly applicable ink strategy for digital additive manufacturing of functional oxide films, contributing to the fabrication of flexible and devices for high-temperature sensing applications.