A Versatile Strategy for the Uniform Patterning of Diverse Functional Materials via Controlled Marangoni Flow.

Abstract

The coffee-ring effect remains a persistent challenge in the solution-based fabrication. While trace surfactants can suppress this effect with little influence on drying time or film residues, such approaches have largely been limited to aqueous systems. Here, we present a surfactant-mediated, humidity-intensified drying strategy that extends this approach to organic solvent-based droplets. The surfactant lowers the surface tension at the droplet edge, driving an inward Marangoni flow from the edge to the center, while elevated relative humidity intensifies this inward flow. This inward Marangoni flow counteracts the outward capillary and Marangoni flows, thereby suppressing the coffee-ring effect and yielding high thickness uniformity. The broad applicability of this drying strategy is demonstrated by fabricating uniform patterns from diverse functional material solutions on both rigid and flexible substrates across various geometries. Its potential for luminescent and electronic devices is evidenced by the realization of large-area fluorescent images, thin-film transistor arrays, and a light-emitting diode display prototype.