Monolayers of two-dimensional transition metal dichalcogenides (2D TMDCs) such as those of MoS2 and WS2 offer a promising alternative to the use of Si in solar energy harvesting and other applications due to their direct bandgaps, high absorption efficiency, and their ultralight and flexible nature. For device applications, such monolayers need to be of large area and high quality. We extend the gold-assisted exfoliation method from MoS2 and WS2 further to ReS2 and ReSe2, to obtain their monolayers on large area of square millimetre size. The image above shows a (false color) optical microscope image of an exfoliated MoS2 monolayer, the size of which was only limited by the size of the crystal used to exfoliate it. We use these large-area monolayers to produce heterostructures, either with other 2D materials or with layers of nanocrystals.
August 31, 2023