Electrons in atomically thin two-dimensional crystals

Summary form only given. Graphene, the 2-dimensional honeycomb lattice of carbon atoms, was first isolated a decade ago. Here we describe advances in our understanding of the properties of electrons confined to this material of single-atom thickness. We emphasize light-matter interactions and potential device applications, from the THz to the ultraviolet. We also highlight the development of atomically thin materials beyond graphene. These advances are exemplified by progress in atomically thin semiconductors, like the transition metal dichalcogenides, which exhibit many distinctive and attractive optical properties, alone and in combination with one another, at monolayer thickness.