LIQUID EXFOLIATION OF TWO-DIMENSIONAL MATERIALS FOR OPTOELECTRONIC DEVICE APPLICATIONS

Abstract

Large-scale liquid exfoliation of 2D materials for printing applications of functional devices is highly attractive due to its low-cost, environmentally friendly, and highly scalable processes compared to conventional methods such as micromechanical exfoliation. However, there are issues that remained to be addressed for the liquid exfoliation method to be usable in the mass-production of 2D materials devices. In this study, the liquid exfoliation process has been optimized to maximize the exfoliation yield by a selection of appropriate solvent mixtures as the dispersing medium and pretreatment process prior to sonication, which significantly increases the exfoliation yield by as much as 100 times. This has enabled the production of highly concentrated 2D materials ink in a much shorter time for printing photodetectors based on 2D materials networks. Furthermore, the size selection of nanosheets and controlled mixing with graphene has been shown to greatly modify the photoresponse speed and responsivity of the photodetectors.