Interlayer donor-acceptor pair excitons in MoSe₂/WSe₂ moire heterobilayer

Localized interlayer excitons (LIXs) in two-dimensional moire superlattices exhibit sharp and dense emission peaks, making them promising as highly tunable single-photon sources. However, the fundamental nature of these LIXs is still elusive. Here, we show the donor-acceptor pair (DAP) mechanism as one of the origins of these excitonic peaks. Numerical simulation results of the DAP model agree with the experimental photoluminescence spectra of LIX in the moire MoSe2/WSe2 heterobilayer. In particular, we find that the emission energy-lifetime correlation and the nonmonotonic power dependence of the lifetime agree well with the DAP IX model. Our results provide insight into the physical mechanism of LIX formation in moire heterostructures and pave new directions for engineering interlayer exciton properties in moire superlattices.