Development of Drop-On-Demand Inkjet Process for the Fabrication of Thin-Film Printed Devices

The main benefit of inkjet printing (IJP) lies in its ability to eliminate the photolithography and etching processes that are fundamental to silicon manufacturing technology. This is due to the direct deposition of solution-processed materials in predefined patterns. Although IJP has been employed in the production of various thin-film devices (TFD), there are still significant challenges in achieving fully printed TFDs. These include adjusting the rheological properties of formulated inks with drop-on-demand (DoD) printers and developing a comprehensive understanding of the parameters and conditions required for the IJP process to yield a desired morphology, film thickness, and pattern area uniformity. This investigation proposes to develop a process for the IJP of solution-processed materials, considering not only the ink rheological properties but also the parameters and setup conditions of the DoD printer employed. Commercial inks with specific rheological properties for IJP are used to print materials patterns with different resolutions, under continuous ejection conditions. The morphology and film thickness variations of the printed material are characterized by employing atomic force microscopy, ellipsometry, and optical microscopy. The obtained results depend on the rheological properties and solid content in the ink, as well as the configured parameters of the DoD printer. These findings can provide valuable evidence for attaining optimal conditions to enhance the surface wettability and develop the stacking of printed patterns of different materials. The focus of this work is on the fabrication of TFDs through a complete IJP process and improving their performance.