关键词: 分子结, 电化学门控, 分子结构, ECSTM-BJ, 增强性量子干涉

Abstract:

Electrochemical gating has emerged as a feasible and powerful method to tune single-molecule conductance. Herein, we demonstrate that the electron transport through single-molecule circuits with two benzene rings in parallel could be efficiently gated by electrochemistry. The molecular junctions with two parallel paths are fabricated with Au electrodes by STM break junction (STM-BJ) technique. Their conductance value exhibits a 2.82-fold enhancement by the constructive quantum interference compared to single-molecule junctions with single path for electron tunneling. Furthermore, the conductance of para-benzene based molecule could be electrochemically tuned with a modulation ratio of about 333%·V^-1. With the help of DFT calculations, a V-shape spectra of energy-dependent transmission coefficients T(E) around E = E_F leads to the conductance gating behavior. The current work sheds a light on the electrochemical gating of single-molecule circuits with parallel paths, and offers a new way to design molecular materials for a high-performance molecular device.

Key words: molecular junctions, electrochemical gating, molecular structure, ECSTM-BJ, constructive quantum interference