Single-molecule junctions of multinuclear organometallic wires: long-range carrier transport brought about by metal-metal interaction

• Published in: Chemical science (Cambridge) Vol. 12; no. 12; pp. 4338 - 4344
• Main Authors: Tanaka, Yuya, Kato, Yuya, Sugimoto, Kaho, Kawano, Reo, Tada, Tomofumi, Fujii, Shintaro, Kiguchi, Manabu, Akita, Munetaka
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 01.01.2021; The Royal Society of Chemistry
• Subjects: Attenuation; Carrier transport; Chemistry; Crystallography; Electrons; Fermi level; Organometallic compounds; Resistance
• ISSN: 2041-6520; 2041-6539
• DOI: 10.1039/d0sc06613c

Here, we report multinuclear organometallic molecular wires having (2,5-diethynylthiophene)diyl-Ru(dppe) 2 repeating units. Despite the molecular dimensions of 2-4 nm the multinuclear wires show high conductance (up to 10 −2 to 10 −3 G 0 ) at the single-molecule level with small attenuation factors ( β ) as revealed by STM-break junction measurements. The high performance can be attributed to the efficient energy alignment between the Fermi level of the metal electrodes and the HOMO levels of the multinuclear molecular wires as revealed by DFT-NEGF calculations. Electrochemical and DFT studies reveal that the strong Ru-Ru interaction through the bridging ligands raises the HOMO levels to access the Fermi level, leading to high conductance and small β values. Multinuclear organometallic molecular wires having (diethynylthiophene)diyl-Ru(dppe) 2 repeating units show high conductance with small attenuation factors. The strong Ru-Ru interaction is the key for the long-range carrier transport.