Exciton-Phonon Coupling Induces a New Pathway for Ultrafast Intralayer-to-Interlayer Exciton Transition and Interlayer Charge Transfer in WS<sub>2</sub>-MoS<sub>2</sub> Heterostructure: A First-Principles Study.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 38888269.
- Also identified by DOI 10.1021/acs.nanolett.4c01508 and PMC identifier 11229060.
- Licence recorded as CC BY.
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Abstract
Despite the weak, van der Waals interlayer coupling, photoinduced charge transfer vertically across atomically thin interfaces can occur within surprisingly fast, sub-50 fs time scales. An early theoretical understanding of charge transfer is based on a noninteracting picture, neglecting excitonic effects that dominate optical properties of such materials. We employ an <i>ab initio</i> many-body perturbation theory approach, which explicitly accounts for the excitons and phonons in the heterostructure. Our large-scale first-principles calculations directly probe the role of exciton-phonon coupling in the charge dynamics of the WS<sub>2</sub>/MoS<sub>2</sub> heterobilayer. We find that the exciton-phonon interaction induced relaxation time of photoexcited excitons at the <i>K</i> valley of MoS<sub>2</sub> and WS<sub>2</sub> is 67 and 15 fs at 300 K, respectively, which sets a lower bound to the intralayer-to-interlayer exciton transfer time and is consistent with experiment reports. We further show that electron-hole correlations facilitate novel transfer pathways that are otherwise inaccessible to noninteracting electrons and holes.