Ultrafast Charge Transfer and Recombination Dynamics in Monolayer-Multilayer WSe 2 Junctions Revealed by Time-Resolved Photoemission Electron Microscopy.

Autor:	Xu C; School of Chemistry, Chemical Engineering and Biotechnology, and School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore., Barden N; School of Chemistry, Chemical Engineering and Biotechnology, and School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore., Alexeev EM; Cambridge Graphene Centre, University of Cambridge, Cambridge CB3 0FA, U.K., Wang X; College of Chemistry, Key Laboratory of Theoretical and Computational Photochemistry, Beijing Normal University, Beijing 100875, People's Republic of China., Long R; College of Chemistry, Key Laboratory of Theoretical and Computational Photochemistry, Beijing Normal University, Beijing 100875, People's Republic of China., Cadore AR; Cambridge Graphene Centre, University of Cambridge, Cambridge CB3 0FA, U.K., Paradisanos I; Cambridge Graphene Centre, University of Cambridge, Cambridge CB3 0FA, U.K., Ott AK; Cambridge Graphene Centre, University of Cambridge, Cambridge CB3 0FA, U.K., Soavi G; Cambridge Graphene Centre, University of Cambridge, Cambridge CB3 0FA, U.K.; Institute of Solid State Physics, Friedrich Schiller University Jena, Max-Wien-Platz 1, 07743 Jena, Germany., Tongay S; School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, Arizona 85287, United States., Cerullo G; Department of Physics, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133 Milano, Italy.; IFN-CNR, Piazza Leonardo da Vinci 32, I-20133 Milano, Italy., Ferrari AC; Cambridge Graphene Centre, University of Cambridge, Cambridge CB3 0FA, U.K., Prezhdo OV; Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States., Loh ZH; School of Chemistry, Chemical Engineering and Biotechnology, and School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore.
Jazyk:	angličtina
Zdroj:	ACS nano [ACS Nano] 2024 Jan 23; Vol. 18 (3), pp. 1931-1947. Date of Electronic Publication: 2024 Jan 10.
DOI:	10.1021/acsnano.3c06473
Abstrakt:	The ultrafast carrier dynamics of junctions between two chemically identical, but electronically distinct, transition metal dichalcogenides (TMDs) remains largely unknown. Here, we employ time-resolved photoemission electron microscopy (TR-PEEM) to probe the ultrafast carrier dynamics of a monolayer-to-multilayer (1L-ML) WSe 2 junction. The TR-PEEM signals recorded for the individual components of the junction reveal the sub-ps carrier cooling dynamics of 1L- and 7L-WSe 2 , as well as few-ps exciton-exciton annihilation occurring on 1L-WSe 2 . We observe ultrafast interfacial hole (h) transfer from 1L- to 7L-WSe 2 on an ∼0.2 ps time scale. The resultant excess h density in 7L-WSe 2 decays by carrier recombination across the junction interface on an ∼100 ps time scale. Reminiscent of the behavior at a depletion region, the TR-PEEM image reveals the h density accumulation on the 7L-WSe 2 interface, with a decay length ∼0.60 ± 0.17 μm. These charge transfer and recombination dynamics are in agreement with ab initio quantum dynamics. The computed orbital densities reveal that charge transfer occurs from the basal plane, which extends over both 1L and ML regions, to the upper plane localized on the ML region. This mode of charge transfer is distinctive to chemically homogeneous junctions of layered materials and constitutes an additional carrier deactivation pathway that should be considered in studies of 1L-TMDs found alongside their ML, a common occurrence in exfoliated samples.
Databáze:	MEDLINE
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