Effect of interlayer spacing on the electronic and optical properties of SnS₂/graphene/SnS₂ sandwich heterostructure: a density functional theory study

The formation of metal dichalcogenide heterostructures enables tailoring their properties for future optoelectronics and energy storage. The current paper focuses on the study of the effect of interlayer spacing on the electronic and optical properties of SnS₂/graphene/SnS₂ sandwich heterostructure, using density functional theory electronic structure calculations. We find low cohesive energies/ per atom ( \(0.0506 \to 0.0514\) $0.0506\to 0.0514$  eV) for all the various interlayer spacing configurations (1–5 Å) considered in this study, implying the feasibility of experimental realization. The Mulliken charge transfer analysis suggests negative to positive net charge ( \(-0.12 \to 0.18\) $-0.12\to 0.18$ ) transfer for 1–3 Å threshold interlayer spacing, which implies acceptor and donor charge transfer configurations. The density of states of SnS₂/graphene/SnS₂ retains unoccupied states for all the interlayer spacing configurations, which can be attributed to localized exciton states and strong electronic coupling between the electrons within the heterostructure layers. We further find a strong optical response and localized electronic transport, which can pave the way for optoelectronic applications of this material heterostructure.