Direct Photopatterning of Green Solvent-Processed 2D Nanomaterials for Wafer-Scale Electronics.

Solution-processed 2D nanomaterials have emerged as key building blocks for the large-scale assembly of functional electronic devices. Solution processing enables the formation of electronically active percolated networks by leveraging van der Waals (vdW) interactions between individual 2D nanosheets. While effective vdW interactions are expected to minimize potential energy barriers and contact resistances between nanosheets, undesired residues from material synthesis or device fabrication processes may remain at the interface. In particular, the ideal solvent candidates for optimizing the stability of 2D dispersions are typically difficult to remove due to their high boiling points and exhibit environmental toxicity. Additionally, conventional patterning processes require multiple solvents, which can disrupt vdW interfaces and degrade device performance. To address these challenges, a comprehensive process that combines 2D dispersion preparation with a cross-linker-based direct photopatterning technique is developed using an eco-friendly green solvent. To enable this process, the stability of 2D nanomaterials and ultraviolet light-sensitive cross-linkers is thoroughly analyzed using Hansen solubility parameters. The developed process successfully enables the preparation of stable dispersions of cross-linkers and 2D nanomaterials, including graphene, molybdenum disulfide, tungsten diselenide, and hafnium disulfide, which can then be assembled via vdW interactions to create large-scale functional electronic devices.