Excitons and polaritons in two-dimensional transition metal dichalcogenides: a tutorial

Since the discovery of two-dimensional transition metal dichalcogenide monolayers as direct bandgap semiconductors with pronounced room-temperature exciton transitions, research on excitons and polaritons in these materials has exploded worldwide. Here, we give an introductory tutorial on the basic properties of excitons and polaritons in these materials, emphasizing how they are different from those in conventional semiconductors, and discuss some of the most exciting new phenomena reported.