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

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 as electrodes to fabricate WTe/metalated tetraphenylporphyrin (M-TPP)/WTe 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/M-TPP/WTe junctions exhibit the tunable conductance from 10 to 10 (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.