Model interlayer-exciton dynamics with hBN-spacer-induced registry variations

Develop a complete model of interlayer-exciton dynamics in WSe2/hBN/WSe2 heterostructures that accounts for the hBN spacer and possible small-twist-induced domains with distinct local registries, selection rules, energies, lifetimes, and recombination pathways, thereby explaining the observed discrepancies between measured and theoretically predicted selection rules and oscillator strengths.

Background

The paper identifies bright singlet and dark triplet interlayer excitons in nominally 0°-aligned WSe2/hBN/WSe2 devices. Although the measured selection rule of the bright interlayer exciton agrees with expectations for R-type stacking, the dark interlayer exciton exhibits a selection rule more consistent with a different stacking order. In addition, theory predicts comparable oscillator strengths for the two species, whereas the experiments show markedly different absorption strengths and lifetimes.

The authors suggest that a small interlayer twist may produce domains with different local registries, each having distinct selection rules, energies, and lifetimes, with recombination dominated by particular registries. A complete dynamical treatment incorporating the hBN spacer and these registry-dependent effects is therefore left unresolved.