In the past, gravure-printed electronics has been limited to printing organic inks and metal nanoparticles. Here we couple an understanding of the physics of gravure printing on glass with strategies for inorganic sol-gel ink design to extend the scope of high-speed printing to new high-performance inorganic materials including transparent conductive oxides (TCOs). We explore the impact that ink design has on material properties such as crystallinity, conductivity, transparency, and performance under mechanical bending stress, leading to effective co-optimization of patterning and TCO performance. Furthermore, these ink design principles are applied to silver nanowire hybrid sol-gel inks which allow gravure printing of high figure of merit mechanically robust, transparent conducting films using low processing temperatures.
Additionally, this thesis will discuss the design and construction of a custom gravure printer for high-speed patterning and accurate registration of printed layers. The novel design allows the decoupling of the individual subprocesses of gravure to allow mechanistic studies of major printing artifacts and improved areal uniformity. A new understanding of the role of gravure contact mechanics in ink transfer and doctoring is presented.
This work also develops high-performance materials for scaling down the process temperatures of printed metal oxide devices. Aqueous ink formulations are explored for inkjet printing transparent electrodes and channel materials in transparent thin film transistors. The unique printing physics, electrical contact properties to aqueous semiconductors, and low-temperature processability of these inks are studied to achieve high-resolution printed TCOs at plastic compatible temperatures below 220 °C. Additionally, low-temperature, UV-annealed high-k dielectrics are presented for processing printed metal oxide transistors. High-performance printed transistors are achieved with high operational stability and connections between bias-stress stability and low-temperature processing are studied.