Manipulating 2D Materials at The Air-Water Interface: Towards Printing on Water

Conventional printing or casting approaches involving colloidal dispersions of 2D materials cannot typically yield films or prints less than 0.1 to 1 micron in thickness. On the other hand, the Langmuir-Blodgett approach can create single molecule thick films since the dispersed material is transferred or printed onto water and even after solvent evaporation, the dispersed phase or pigment remains mobile on the liquid water substrate. This mobility allows the floating material to be compressed by the moveable barriers of a Langmuir-Blodgett trough. However, this mechanical approach limits coatings to small areas (~cm²) and is not amenable to roll-to-roll, high throughput processing. In this talk, I will summarize various works from my group that aim to understand how to use this interfacial mobility to adapt the Langmuir-Blodgett approach to one capable of printing and patterning continuously and over large areas. As an example, we explore the performance of such films comprised of electrochemically exfoliated transition metal dichalcogenides as transistors and photodetectors.