Unveiling exciton many-body interactions in WS2 single crystal

Understanding the exciton many-body interactions and their recombination dynamics in transition metal dichalcogenides (TMDCs) are important for potential applications in optoelectronics and valleytronics. Herein, using ultrafast non-degenerate transient differential reflectance spectroscopy, we studied exciton interactions in WS2 single crystal. Spectrally and temporally resolved studies revealed the strong interrelated excitonic interactions of A, B and C excitons and associated transient stark blueshift and broadening of exciton resonances. Additionally, we observed an unusual prolonged decay of direct band-gap exciton (A exciton) with fluence, which interprets the presence of trap state in the system. Our findings provide a comprehensive understanding of material’s intrinsic properties and exciton many-body physics which offers efficient pathways to optoelectronic applications based on TMDCs.