SUBJECT: Ph.D. Dissertation Defense
BY: Ara Parsekian
TIME: Wednesday, December 4, 2019, 12:00 p.m.
PLACE: MRDC Building, 4211
TITLE: Solution Processing of Stripes, Patches and Digital Patterns Using a Novel Slot Coating-inspired Approach
COMMITTEE: Dr. Tequila A. L. Harris, Chair (ME)
Dr. Minami Yoda (ME)
Dr. Suresh K. Sitaraman (ME)
Dr. John R. Reynolds (CHEM)
Dr. Victor Breedveld (CHBE)


In recent decades, printing and coating techniques have received interest for manufacturing of low-cost wearable electronics, sensors, displays, photovoltaics, and energy storage devices. Since deposition of high-resolution pattern features across a wide area is not easily scalable with established techniques, novel manufacturing methods are needed to ensure commercial viability of various low-cost printed devices. This dissertation discusses slot coating-inspired approaches to generate micro-scale pattern features, without costly pre-patterning or post-deposition subtractive steps. The slot die approach deposits pre-metered coating fluid through a narrow liquid bridge onto a moving substrate. Manipulation of the shape and volume of the liquid bridge constitutes one avenue for process control over feature size, and this work provides an empirical modeling methodology relating dynamic wetting and liquid bridge phenomena to pattern morphology. In addition, patterning can be achieved through co-deposition of a support material to define continuous alternating-stripe features. Selection of the support material is informed by diffusion mixing inside the coating tool, as well as wetting equilibrium of the heterogeneous liquid film. Furthermore, an analytical model of the co-laminar flow inside the coating tool is developed to support feature size reduction through hydrodynamic focusing. The model finds good agreement with flow visualizations inside the physical coating tool. Finally, deposition of conductive polymer and metallic nanoparticle inks in narrow-stripe structures is demonstrated on a pilot-scale roll-to-roll manufacturing system.