Environment-dependent Interlayer Exciton Behaviors in Atomically Thin Hybrid Heterostructures

Interlayer excitons (IX), formed in 2D transition metal dichalcogenide (TMD) heterostructures, have attracted significant attention to realize future optoelectronics such as spintronics and excitonic devices. Despite the advances, environmental effects, including dielectric screening, separation length of electron-hole pair in IX and interlayer charge transfer, are not fully understood. To better understand the effects, we introduce organic-layer-embedded MoS₂/organic/WSe₂ hybrids. The inserted molecular layer enhances the dielectric screening with a reduced dielectric constant and an increased separation length, thereby reducing IX binding energy. In addition, the interlayer charge transfer in the hybrid is regulated by the nature of the organic layer. The layer forming type-II junctions with TMDs converts the charge transfer pathway from tunneling to band-assisted transfer. This allows an energetically favorable transfer, facilitating a greater population of IX. As a result, a stronger IX-IX interaction is observed, which consequently leads to the higher energy of IX in the hybrid. Lastly, the IX formation may also be prohibited by introducing electron or hole trapping organic layers. This work may provide a deeper understanding on IX for realizing IX-based applications.