Weak distance dependence of hot-electron-transfer rates at the interface between monolayer MoS₂ and gold

• Main Authors: Xu, Ce, Yong, Hui Wen, He, Jinlu, Long, Run, Cadore, Alisson R., Paradisanos, Ioannis, Ott, Anna K., Soavi, Giancarlo, Tongay, Sefaattin, Cerullo, Giulio, Ferrari, Andrea C., Prezhdo, Oleg V., Loh, Zhi-Heng
• Other Authors: School of Physical and Mathematical Sciences
• Format: Article
• Language: English
• Published: 2022
• Subjects: Science::Chemistry; Charge Transfer; Interfaces
• Online Access: https://hdl.handle.net/10356/155540
• Institution: Nanyang Technological University

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.