Distinct Exciton Dynamics and Gate Tunability in Two-Dimensional Moiré Heterobilayers

Transition metal dichalcogenide (TMD) moiré heterobilayers provide a versatile platform for exploring correlated excitonic phenomena and next-generation optoelectronic devices. The field-tunable band alignment, combined with the moiré superlattice, gives rise to unconventional exciton-exciton and exciton-charge interactions. In this work, we report distinct exciton dynamics and gate-controlled excitonic responses in WS₂/WSe₂ and WS₂/MoSe₂ moiré heterobilayers. First, by modeling the efficiency droop and bimolecular recombination processes, we extract an ultralow exciton-exciton annihilation coefficient on the order of 10^-5 cm²s^-1. Second, by tuning the gate voltage, we further observe continuous modulation of charged exciton states and recombination rates. These results highlight the crucial role of Coulomb interactions in governing microscopic exciton scattering pathways in moiré systems.