Carbon-rich organometallics: Application to molecular electronics

MMM (metal & ndash;molecule-metal) junction exhibiting wire-like functions is an essential component of molecular circuit/electronics. Herein reviewed are recent advances in the study of single molecule con-ductance behavior of MMM junctions based on carbon-rich organometallics, with a particular focus on the mono-and oligo-nuclear, linear trans-Ru(phosphine)4-acetylide linkages. The conductance of MMM junctions determined by the STM-BJ (scanning tunneling microscopy-break junction) method has drasti-cally improved by energy alignment between the wire part and the electrodes by tuning the components of the organometallic wire part (e.g. metal, ligand, organic linker, and anchor). The efficient energy align-ment of carbon-rich organometallic systems arises from (i) the contribution of the metal d-electrons being higher in energy than the 2 s-and 2p-electrons used for purely organic junctions and much closer to the d-electron levels of metal electrodes and (ii) covalent interactions not only between anchor and electrode but also between metal and organic linker. As a result, the excellent long range carrier transport up to ti 4 nm with 10-2 G0 level conductance has been achieved. Conductance behavior of MMM junc-tions has been successfully interpreted in terms of transmission spectra obtained by the hybrid DFT-NEGF (non-equilibrium Green function) calculations. (c) 2022 Elsevier B.V. All rights reserved. Superscript/Subscript Available

Automated summary

This review discusses recent advances in the study of single molecule conductance behavior of MMM junctions based on carbon-rich organometallics. Energy alignment between the wire part and the electrodes has significantly improved the conductance of MMM junctions, achieving long range carrier transport.