From super-lubricants, to solar cells, to the fledgling technology of valleytronics, there is much to be excited about with the discovery of a unique new two-dimensional semiconductor, rhenium disulfide, by a large international team of Molecular Foundry users. Rhenium disulfide (ReS2), unlike molybdenum disulfide and other dichalcogenides, behaves electronically as if it were a 2D monolayer even as a 3D bulk material. This not only opens the door to 2D electronic applications with a 3D material, it also makes it possible to study 2D physics with easy-to-make 3D crystals.
Bulk rhenium disulphide behaves as electronically and vibrationally decoupled monolayers. This unique response originates from the lack of interlayer registry and weak interlayer coupling, as confirmed by high-resolution transmission electron microscopy (HRTEM), electron diffraction and density functional theory (DFT) calculations. Consequently, from bulk to monolayers, ReS2 remains a direct-bandgap semiconductor, its photoluminescence (PL) intensity increases, whereas its Raman spectrum remains unchanged with increasing number of layers.