Determine the excited-state character of CH$_\mathrm{S}^{-}$ in the complete experimental heterostructure

Determine the electron–hole composition and binding energy of the CH$_\mathrm{S}^{-}$ optical transition in the experimentally relevant MoS$_2$/hBN(2L)/graphene heterostructure, including how the second hBN layer and graphene substrate modify the unoccupied defect state through dielectric screening, band alignment, and defect–host hybridization.

Background

The calculations model CHS−_\mathrm{S}^{-} in a MoS2_2/hBN heterostructure containing only one hBN layer and omit the second hBN layer and graphene substrate present in the experiment. In the calculated model, the optical transition involves defect character in both the initial and final states, whereas the experimental interpretation describes an acceptor-bound exciton formed by recombination between a conduction-band state and an occupied acceptor-like defect state.

The authors state that the omitted layers could alter dielectric screening, band alignment, and hybridization, potentially changing the character of the unoccupied state. A rigorous resolution requires a GWGW–BSE calculation for the defective heterostructure, which was not performed because of computational limitations.

References

This question is therefore left for future investigation with sufficient computational resources. A rigorous determination of the electron--hole composition and binding energy would further clarify this point, but this requires a $GW$-BSE calculation for the defective heterostructure, which is beyond the computational capability of the present work.

— Theory of the CH$_\text{S}^-$ Defect in MoS$_2$ Confirming the Origin of the Quantum Emission  (2610.12283 - Cholsuk et al., 8 Oct 2026) in Discussion, paragraph beginning “Such the position and character of the unoccupied defect state…”