Single-Atom Control of Single-Molecule van der Waals Junctions with Semimetallic Transition Metal Dichalcogenide Electrodes

Abstract

Electrodes play an essential role in controlling electrode−molecule coupling. However, conventional metal electrodes require linkers to anchor the molecule. Van der Waals interaction offers a versatile strategy to connect the electrode and molecule without anchor groups. Except for graphene, the potential of other materials as electrodes to fabricate van der Waals molecular junctions remains unexplored. Herein, we utilize semimetallic transition metal dichalcogenides (TMDCs) 1T′-WTe 2 as electrodes to fabricate WTe 2 /metalated tetraphenylporphyrin (M-TPP)/WTe 2 junctions via van der Waals interaction. Compared with chemically bonded Au/M-TPP/Au junctions, the conductance of these M-TPP van der Waals molecular junctions is enhanced by ∼736%. More importantly, WTe 2 /M-TPP/WTe 2 junctions exhibit the tunable conductance from 10 −3.29 to 10 −4.44 G 0 (1.15 orders of magnitude) via single-atom control, recording the widest tunable range of conductance for M-TPP molecular junctions. Our work demonstrates the potential of two-dimensional TMDCs for constructing highly tunable and conductive molecular devices.

Evolution of Single-Molecule Electronic Interfaces

“…(f) TVS result of the WTe 2 /Fe-TPP/WTe 2 molecular junction. Reproduced with permission from ref . Copyright 2023, American Chemical Society.…”

“…By modulating localized edge states on the interface atoms, non-carbon 2D material electrodes promote charge transfer at the molecule–electrode interface and reduce contact resistance. Hong et al constructed STM-BJ-based WTe 2 /M-TPP/WTe 2 molecular junctions (Figure e), where the easily tunable energy bands and interface structure of transition metal disulfur compounds are advantages over graphene . The transition voltage V trans = 0.23 V extracted from the TVS of the WTe 2 /Fe-TPP/WTe 2 molecular junction is much smaller than most of the molecular junctions formed by the gold electrodes (Figure f).…”

Simultaneous exfoliation and functionalization of MoS2 with tetrapyridyl porphyrin

“…Due to their large conjugated π-system, planar conformation and π–π stacking ability, porphyrins have been employed for the construction of several assemblies with different nanomaterials, such as graphene, 45,46 carbon nanotubes, 47,48 carbon nitride, 49,50 and several TMDs. 51–53…”