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

Electrodes play an essential role in controlling electrode-moleculecoupling. However, conventional metal electrodes require linkers toanchor the molecule. Van der Waals interaction offers a versatilestrategy to connect the electrode and molecule without anchor groups.Except for graphene, the potential of other materials as electrodesto fabricate van der Waals molecular junctions remains unexplored.Herein, we utilize semimetallic transition metal dichalcogenides (TMDCs)1T & PRIME;-WTe2 as electrodes to fabricate WTe2/metalated tetraphenyl-porphyrin (M-TPP)/WTe2 junctionsvia van der Waals interaction. Compared with chemically bonded Au/M-TPP/Aujunctions, the conductance of these M-TPP van der Waals molecularjunctions is enhanced by & SIM;736%. More importantly, WTe2/M-TPP/WTe2 junctions exhibit the tunable conductancefrom 10(-3.29) to 10(-4.44) G (0) (1.15 orders of magnitude) via single-atomcontrol, recording the widest tunable range of conductance for M-TPPmolecular junctions. Our work demonstrates the potential of two-dimensionalTMDCs for constructing highly tunable and conductive molecular devices.