Ultrafast\nInterlayer Charge Transfer between Bilayer\nPtSe₂ and Monolayer WS₂

Abstract

Interlayer\ncharge transfer (CT) between PtSe₂ and WS₂ is\nstudied experimentally. Layer-selective pump–probe\nand photoluminescence quenching measurements reveal ultrafast interlayer\nCT in the heterostructure formed by bilayer PtSe₂ and monolayer\nWS₂, confirming its type-II band alignment. The CT facilitates\nthe formation of the interlayer excitons with a lifetime of several\nhundred ps to 1 ns, a diffusion coefficient of 0.9 cm² s^–1, and a diffusion length reaching 200 nm. These results\ndemonstrate the integration of PtSe₂ with other materials\nin van der Waals heterostructures with novel charge-transfer properties\nand help develop fundamental understanding on the performance of various\noptoelectronic devices based on heterostructures involving PtSe₂.