Moiré-Trapped Interlayer Exciton dynamics in a WSe₂/MoSe₂ Heterobilayer

Transition-metal dichalcogenide heterobilayers can host interlayer excitons (IXs) trapped in moiré potentials with tailored electronic band structures and strong dipolar interactions, promising for realizing exciton ordering and nonlinear exciton switches at quantum limit. The temporal dynamics of moiré-trapped IXs can offer extra insight into how the IXs are interacting in the moiré trapping site, yet it is thoroughly studied. Here we use CW photoluminescence (PL) spectroscopy to reveal the evolution from single photon emitters to broad spin singlet/triplet ensemble peaks of moiré-trapped IX in a charge neutral WSe₂/MoSe₂ heterostructure, highlighting a dipolar-induced Coulomb interaction which results in up to 8.5 meV blue shift in emission energy. Complementary to the spectral feature, using pulsed laser excitation we reveal the power-dependent lifetime of the spin triplet exciton ensemble peak. As we increase power across three orders of magnitude, we observe a continuously decreasing lifetime. We interpret the evolution of the temporal dynamics by considering strong dipolar interactions, exciton density (i.e., inter-exciton distance) as well as the exciton-exciton annihilation rate. Our study provides insights for exciton dynamics in state-of-the-art moiré heterobilayers, and represents a steppingstone to pursue complex phenomena like quantum phase transitions of IXs.