Ultrafast Carrier Dynamics Near A, B, and C Excitons in Monolayer MoS₂ under High Excitation Densities: A Comparative Study

With the rising demand for monolayer MoS₂ in diverse optoelectronic applications, understanding carrier dynamics across various excitation conditions and excitonic levels has become essential. In this study, we demonstrate that carrier behavior in monolayer MoS₂ is significantly influenced by band structure, excitation wavelength, and excitation density. At the A and B excitonic levels, we observe an initial bandgap renormalization driven by exciton dissociation near the band edge. In contrast, at the C-excitonic state, band bleaching becomes prominent due to enhanced exciton formation from the high density of available states. This excitation energy also leads to carrier relaxation and thermalization through lattice interactions, releasing numerous hot phonons and creating a bottleneck effect that prolongs carrier relaxation time due to hot phonon accumulation.