Tailoring Light–Matter Interactions in 2D Semiconductors

Conspectus: Two-dimensional (2D) crystals have had a sweeping influence on the condensed matter physics and materials science communities for over two decades. Their thinness and ability to be configured into layered and twisted heterostructures has enabled 2D crystals to become a platform material of choice to uncover many intriguing phenomena, including superconductivity, the fractional quantum anomalous Hall effect, spin textures, strain domain walls, and distinct spin–valley transitions. This versatility is on display in 2D semiconductor monolayers, which exhibit strong light–matter coupling to a rich host of excitonic states and valley selective transitions. The optical physics of 2D semiconductors is tunable through manipulation of their structure, chemical composition, mutual orientation in superlattices, and strain. Together, such adjustments give rise to a plethora of exciting applications in optics, spintronics, and quantum sensing. Our contributions to the 2D materials community have focused on developing chemical strategies for precision nanostructure synthesis, elucidating emergent optical phenomena through detailed spectroscopic analysis, and creating new 2D heterostructures that support the localization and manipulation of quasiparticle states. This Account examines selected aspects of our recent work on tailoring light–matter interactions in 2D semiconductors. We discuss how synthetic manipulation of a 2D crystal’s dimensions, edge structure, strain state, and coupling to other molecular species and lattices renders specific properties. Through this article we wish to draw attention to the rich chemistry of 2D crystals and the active role chemistry should play in opening new avenues of research in 2D materials.