Morikawa Takanori, Tsutsui Makusu, Komoto Yuki, Yokota Kazumichi, Taniguchi Masateru
The Institute of Scientific and Industrial Research, Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan.
National Institute of Advanced Industrial Science and Technology, Takamatsu, Kagawa 761-0395, Japan.
J Phys Chem Lett. 2022 Jul 14;13(27):6359-6366. doi: 10.1021/acs.jpclett.2c01780. Epub 2022 Jul 7.
A molecule-scale diode is an essential component for the concept of molecular electronics. Here we report on heterogeneous contact-mediated rectifying behavior in single-molecule junctions. We performed massive current versus voltage characteristics measurements of metal-molecule-metal structures under stretching by a mechanical break junction method. deformations of the molecular bridges were revealed to induce stochastic switching of the rectifying direction to varying rectification ratio derived from the induced asymmetry in the contact motifs at the molecule termini. Aromatic molecules were found to enable stronger rectifications via the more pronounced Fermi pinning effect to shift the molecular orbital levels by the applied voltage. Dissimilar anchoring groups also served to stabilize the single-molecule diode properties by bestowing a chemically defined difference in the electronic coupling strengths at the electrode-molecule links. The present findings provide a guide to design diodes with the smallest and simplest structures.
分子尺度的二极管是分子电子学概念中的关键组件。在此，我们报告单分子结中异质接触介导的整流行为。我们通过机械断裂结方法对拉伸状态下的金属-分子-金属结构进行了大量电流-电压特性测量。结果表明，分子桥的变形会引发整流方向的随机切换，整流比也会因分子末端接触模式的不对称性而变化。研究发现，芳香族分子通过更显著的费米钉扎效应，在施加电压时使分子轨道能级发生移动，从而实现更强的整流效果。不同的锚定基团还通过在电极-分子连接处赋予化学定义明确的电子耦合强度差异，来稳定单分子二极管的性能。本研究结果为设计结构最小且最简单的二极管提供了指导。
