Mechanically Induced Switching between Two Discrete Conductance States: A Potential Single-Molecule Variable Resistor

作者：Lin-Qi Pei, John R. Horsley, Jing-Wen Seng, Xu Liu, Yuan Qi Yeoh, Ming‐Xia Yu, Xiaohui Wu, Andrew D. Abell, Ju‐Fang Zheng, Xiao‐Shun Zhou, Jingxian Yu, Shan Jin · 发表于：ACS Applied Materials & Interfaces · 年份：2021 · DOI：10.1021/acsami.1c12151 · 被引用次数：32 · 研究领域：Molecular Junctions and Nanostructures、Advanced Memory and Neural Computing、Nanowire Synthesis and Applications

The fabrication of solid-state single-molecule switches with high on–off conductance ratios has been proposed to advance conventional technology in areas such as molecular electronics. Herein, we employed the scanning tunneling microscope break junction (STM-BJ) technique to modulate conductance in single-molecule junctions using mechanically induced stretching. Compound 1a possesses two dihydrobenzothiophene (DHBT) anchoring groups at the opposite ends linked with rigid alkyne side arms to form a gold–molecule–gold junction, while 1b contains 4-pyridine-anchoring groups. The incorporation of ferrocene into the backbone of each compound allows rotational freedom to the cyclopentadienyl (Cp) rings to give two distinct conductance states (high and low) for each. Various control experiments and suspended junction compression/retraction measurements indicate that these high- and low-conductance plateaus are the results of conformational changes within the junctions (extended and folded states) brought about by mechanically induced stretching. A high–low switching factor of 42 was achieved for 1a, whereas an exceptional conductance ratio in excess of 2 orders of magnitude (205) was observed for 1b . To the best of our knowledge, this is the highest experimental on–off conductance switching ratio for a single-molecule junction exploiting the mechanically induced STM-BJ method. Computational studies indicated that the two disparate conductance states observed for 1a and 1b result fr...