Stacking-Controlled Nonequilibrium Mott Dynamics of Moiré Excitons

Moiré superlattices of twisted transition-metal dichalcogenides provide an ideal setting for exploring strongly correlated excitonic phases in two dimensions. In this work, we reveal that the stacking registry in WSe₂/WS₂ heterobilayers crucially determines the nature of many-body interactions and nonequilibrium Mott dynamics of interlayer excitons. Using time-resolved optical spectroscopy, we uncover a distinct correlated state in H-stacked configurations, where quadrupole interactions stabilize a doublon-like excitonic complex beyond unit filling. This complex exhibits a characteristic blueshift and markedly prolonged valley lifetime, contrasting the dipolar response observed in R-stacks. The prolonged doublon dynamics delay the excitonic Mott transition, leading to a transient, valley-polarized Mott phase with nanosecond persistence. These findings highlight van der Waals stacking as a key control knob for tailoring correlated excitonic states and driven–dissipative quantum phenomena in moiré semiconductors.