Uniform droplet printing of graphene micro-rings based on multiple droplets overwriting and coffee-ring effect

摘要

The droplet-based patterning of graphene is extremely intriguing and essential for the construction of graphene patterns and their applications in electronic devices. Unfortunately, the fabrication of complete and significant graphene micro-rings still faces considerable challenges. We demonstrated an effective and novel method to fabricate graphene micro-rings with continuous and dense edges based on multiple droplets overwriting and coffee-ring effect. The appropriate deposition time interval and regime map to acquire micro-rings were determined. By using the suitable time interval, the enhanced micro-rings which have densely-packed edges with 30 pm in width and 4000 nm in height and discrete inner residuals were printed by droplets overwriting. We attributed the stronger ring patterns to the longer particle migration time and multi-times migration. Moreover, enhanced micro-rings with broader and thicker edges could be fabricated as the overwriting layers increase. This work opens novel perspectives for the graphene micro-rings fabrication, which might contribute to the morphology regulation and prospect applications of graphene materials, as well as the guidance on the self-assembly of other functional materials.