State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Beijing National Laboratory for Molecular Sciences, National Biomedical Imaging Center, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China.
Center for the Physics of Materials and Department of Physics, McGill University, Montreal, Quebec H3A 2T8, Canada.
J Am Chem Soc. 2021 Dec 15;143(49):20811-20817. doi: 10.1021/jacs.1c08997. Epub 2021 Nov 30.
The aim of molecular electronics is to miniaturize active electronic devices and ultimately construct single-molecule nanocircuits using molecules with diverse structures featuring various functions, which is extremely challenging. Here, we realize a gate-controlled rectifying function (the on/off ratio reaches ∼60) and a high-performance field effect (maximum on/off ratio >100) simultaneously in an initially symmetric single-molecule photoswitch comprising a dinuclear ruthenium-diarylethene (Ru-DAE) complex sandwiched covalently between graphene electrodes. Both experimental and theoretical results consistently demonstrate that the initially degenerated frontier molecular orbitals localized at each Ru fragment in the open-ring Ru-DAE molecule can be tuned separately and shift asymmetrically under gate electric fields. This symmetric orbital shifting (AOS) lifts the degeneracy and breaks the molecular symmetry, which is not only essential to achieve a diode-like behavior with tunable rectification ratio and controlled polarity, but also enhances the field-effect on/off ratio at the rectification direction. In addition, this gate-controlled symmetry-breaking effect can be switched on/off by isomerizing the DAE unit between its open-ring and closed-ring forms with light stimulus. This new scheme offers a general and efficient strategy to build high-performance multifunctional molecular nanocircuits.
分子电子学的目标是使有源电子器件微型化，并最终使用具有各种功能的不同结构的分子构建单分子纳米电路，这极具挑战性。在这里，我们在最初对称的单分子光开关中实现了栅极控制的整流功能（开关比达到约 60）和高性能场效应（最大开关比> 100），该光开关由夹在石墨烯电极之间的双核钌-二芳基乙烯（Ru-DAE）配合物组成。实验和理论结果均一致表明，在开环 Ru-DAE 分子中每个 Ru 片段处的最初简并的前沿分子轨道可以分别进行调谐，并在栅极电场下不对称地移动。这种对称轨道移动（AOS）消除了简并性并打破了分子对称性，这不仅对于实现具有可调整流比和控制极性的类似二极管的行为至关重要，而且还增强了整流方向上的场效应开关比。此外，通过用光刺激将 DAE 单元在其开环和闭环形式之间进行互变，可以打开/关闭这种栅控对称破缺效应。这种新方案提供了一种构建高性能多功能分子纳米电路的通用且高效的策略。
