Ultrafast Interlayer Charge Transfer between Bilayer PtSe₂ and Monolayer WS₂

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Van der Waals heterostructures offer unique electronic and optoelectronic properties.
• Platinum diselenide (PtSe₂) and tungsten disulfide (WS₂) are promising 2D materials for advanced devices.

Purpose of the Study:

• To experimentally investigate interlayer charge transfer (CT) between PtSe₂ and WS₂.
• To confirm the band alignment and characterize the properties of interlayer excitons in PtSe₂/WS₂ heterostructures.

Main Methods:

• Layer-selective pump-probe spectroscopy.
• Photoluminescence quenching measurements.

Main Results:

• Ultrafast interlayer CT was observed in a bilayer PtSe₂/monolayer WS₂ heterostructure.
• Type-II band alignment was confirmed, facilitating interlayer exciton formation.
• Interlayer excitons exhibited long lifetimes (hundreds of ps to 1 ns) and high diffusion coefficients (0.9 cm²/s).

Conclusions:

• The study demonstrates novel charge-transfer properties in PtSe₂-based van der Waals heterostructures.
• Understanding these properties is crucial for developing high-performance optoelectronic devices.