Regensburg 2025 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 13: Molecular Electronics and Excited State Properties I

CPP 13.5: Talk

Monday, March 17, 2025, 18:15–18:30, H38

Effect of Junction Structure on Quantum Interference in Single-Molecule Junctions — •Aoshi Yamane, Shintaro Fujii, and Tomoaki Nishino — Department of Chemistry, School of Science, Institute of Science Tokyo, 2-12-1 Ookayama, Meguro-ku, Tokyo, Japan

The destructive quantum interference (DQI) effect in single-molecule junctions induces a steep decrease in electron transmission at specific energies, enables high on/off ratios of electrical conductivity, and is expected to be applied to molecular devices such as transistors and switches. Here, we aimed to elucidate the effects of molecular and molecule/metal interface structures on DQI. We focused on disubstituted naphthalene with different types and positions of anchoring groups connecting molecules and electrodes. Break junction measurements of the molecular junctions demonstrated that for naphthalenedithiol (NDT), 2,7-NDT showed significantly lower conductivity compared to 2,6-NDT, indicating the presence of DQI in 2,7-NDT. On the other hand, for naphthalenedicarbonitrile (NDCN), 2,6-NDCN and 2,7-NDCN showed similar conductance. Combined with Flicker noise analysis and DFT-NEGF transmission calculations, we demonstrate that the DQI features in 2,7-NDCN are masked by the contribution of electrode-π coupling, which short-circuit the molecular junctions. The present study provides important insights into the control of unique electron transport properties induced by DQI in single-molecule junctions.

Keywords: single-molecule junction; quantum interference; molecular electronics; break junction method; non-equilibrium Green's function method