Epitaxial Synthesis of Monolayer PtSe₂ Single Crystal on MoSe₂ with Strong Interlayer Coupling

PtSe₂, a layered two-dimensional transition-metal dichalcogenide (TMD), has drawn intensive attention owing to its layer-dependent band structure, high air stability, and spin-layer locking effect which can be used in various applications for next-generation optoelectronic and electronic devices or catalysis applications. However, synthesis of PtSe₂ is highly challenging due to the low chemical reactivity of Pt sources. Here, we report the chemical vapor deposition of monolayer PtSe₂ single crystals on MoSe₂. The periodic Moiré patterns from the vertically stacked heterostructure (PtSe₂/MoSe₂) are clearly identified via annular dark-field scanning transmission electron microscopy. First-principles calculations show a type II band alignment and reveal interface states originating from the strong-weak interlayer coupling (SWIC) between PtSe₂ and MoSe₂ monolayers, which is supported by the electrostatic force microscopy imaging. Ultrafast hole transfer between PtSe₂ and MoSe₂ monolayers is observed in the PtSe₂/MoSe₂ heterostructure, matching well with the theoretical results. Our study will shed light on the synthesis of Pt-based TMD heterostructures and boost the realization of SWIC-based optoelectronic devices.