Weak Distance Dependence of Hot-Electron-Transfer Rates at the Interface between Monolayer MoS2 and Gold

Ce Xu; Hui Wen Yong; Jinlu He; Run Long; Alisson R Cadore; Ioannis Paradisanos; Anna K Ott; Giancarlo Soavi; Sefaattin Tongay; Giulio Cerullo; Andrea C Ferrari; Oleg V Prezhdo; Zhi-Heng Loh

doi:10.1021/acsnano.0c07350

Weak Distance Dependence of Hot-Electron-Transfer Rates at the Interface between Monolayer MoS₂ and Gold

ACS Nano. 2021 Jan 26;15(1):819-828. doi: 10.1021/acsnano.0c07350. Epub 2020 Dec 21.

Authors

Ce Xu¹, Hui Wen Yong¹, Jinlu He², Run Long², Alisson R Cadore³, Ioannis Paradisanos³, Anna K Ott³, Giancarlo Soavi^{3

4}, Sefaattin Tongay⁵, Giulio Cerullo^{6

7}, Andrea C Ferrari³, Oleg V Prezhdo⁸, Zhi-Heng Loh^{1

9}

Affiliations

¹ Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore.
² College of Chemistry, Key Laboratory of Theoretical and Computational Photochemistry, Beijing Normal University, Beijing 100875, People's Republic of China.
³ Cambridge Graphene Centre, University of Cambridge, Cambridge CB3 0FA, United Kingdom.
⁴ Institute for Solid State Physics, Abbe Center of Photonics, Friedrich-Schiller-University Jena, Max-Wien-Platz 1, 07743 Jena, Germany.
⁵ School for Engineering of Matter, Transport, and Energy, Arizona State University, Tempe, Arizona 85287, United States.
⁶ Department of Physics, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133 Milano Italy.
⁷ IFN-CNR, Piazza Leonardo da Vinci 32, I-20133 Milano, Italy.
⁸ Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States.
⁹ Centre for Optical Fibre Technology, The Photonics Institute, Nanyang Technological University, Singapore 639798, Singapore.

PMID: 33347267
DOI: 10.1021/acsnano.0c07350

Abstract

Electron transport across the transition-metal dichalcogenide (TMD)/metal interface plays an important role in determining the performance of TMD-based optoelectronic devices. However, the robustness of this process against structural heterogeneities remains unexplored, to the best of our knowledge. Here, we employ a combination of time-resolved photoemission electron microscopy (TR-PEEM) and atomic force microscopy to investigate the spatially resolved hot-electron-transfer dynamics at the monolayer (1L) MoS₂/Au interface. A spatially heterogeneous distribution of 1L-MoS₂/Au gap distances, along with the sub-80 nm spatial- and sub-60 fs temporal resolution of TR-PEEM, permits the simultaneous measurement of electron-transfer rates across a range of 1L-MoS₂/Au distances. These decay exponentially as a function of distance, with an attenuation coefficient β ∼ 0.06 ± 0.01 Å^-1, comparable to molecular wires. Ab initio simulations suggest that surface plasmon-like states mediate hot-electron-transfer, hence accounting for its weak distance dependence. The weak distance dependence of the interfacial hot-electron-transfer rate indicates that this process is insensitive to distance fluctuations at the TMD/metal interface, thus motivating further exploration of optoelectronic devices based on hot carriers.

Keywords: TMD/metal interface; hot carriers; time-resolved photoemission electron microscopy; transition-metal dichalcogenides; ultrafast spectroscopy.