Excitonic Effects in Single Layer MoS2 Probed by Broadband Two-Dimensional Electronic Spectroscopy

Atomically thin Transition-metal dichalcogenides (TMDs) have come into the spotlight in optoelectronics thanks to their outstanding physical properties [1,2]. In single-layer (1L) TMDs strong quantum confinement effects cause a weak screening of Coulomb, so that the excitons created by photo-excitation have large binding energy, up to several hundred meVs [3]. While the steady-state properties of TMDCs have been studied in detail by linear optical techniques, the recent application of time-resolved nonlinear spectroscopy (mainly ultrafast pump-probe) has enabled the study of excited-state dynamics on femtosecond timescales [4] opening up questions about the mechanisms of exciton relaxations and exciton-exciton interactions.