Orientation preference control: a novel approach for tailoring molecular electronic functionalities
Orientation preference control: a novel approach for tailoring molecular electronic functionalities
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方向偏好控制：一种定制分子电子功能的新方法
DOI：
10.1039/d3tc02838k
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发表时间：
2023
影响因子：
6.4
通讯作者：
Wang X
中科院分区：
文献类型：
--
作者：
Wang X
具有不对称锚定的分子导线在分子电子学领域引起了极大的兴趣。许多研究都集中在单分子和自组装单分子膜(SAM)水平上的不对称锚定分子。然而，很少有研究研究不对称锚对底物的结合偏好如何影响其量子传输行为。在本研究中，一端带有乙酸硫醇和另一端带有吡啶锚定的低聚芳纶衍生物被用于自组装，金和单层石墨烯(SLG)作为底电极和顶电极形成分子结。XPS结果表明，在没有去保护乙酸硫酯上的乙酰基的情况下，分子倾向于以硫醇锚定或吡啶锚定在金表面上聚集。然而，随着去保护过程(将硫醇醋酸酯转化为硫醇)，几乎所有的分子都倾向于与硫醇锚一起聚集在Au表面。此外，量子输运测量表明，电子隧穿效率和电极费米能级与分子前线轨道之间的能量差也由于这种结合择优的变化而移动。例如，功能性SAM的场效应晶体管行为可以在双极(分子可以通过在正或负方向上移动栅极电压来打开分子，类似于双极MOS-FET)和单极(分子只能通过在负方向上移动栅极电压来打开分子，类似于n型MOS-FET)之间切换。这项研究表明，除了分子结构工程，分子的电子功能，如隧道效率和开关行为，也可以通过自组装过程中的结合偏好控制来调节。这些发现为制造先进的量子技术设备提供了一种新的方法。
Molecular wires with asymmetric anchors have garnered considerable interest in the field of molecular electronics. Numerous studies have focused on asymmetrically anchored molecules at both single-molecule and self-assembled monolayer (SAM) levels. However, few studies have investigated how the binding preference of asymmetric anchors towards the substrate affects their quantum transport behavior. In this study, oligo(arylene ethynylene) derivatives with thiol acetate anchors at one terminal and pyridine anchors at the other terminal were used for self-assembly, and gold and single-layered graphene (SLG) were employed as the bottom and top electrodes to form molecular junctions. XPS results indicated that, without deprotecting the acetyl group on thiol acetate, the molecules tended to assemble on the Au surface with either the thiol anchor or pyridine anchor. However, with the deprotection procedure (which transformed the thiol acetate into thiol), almost all molecules tended to assemble on the Au surface with the thiol anchor. Furthermore, quantum transport measurements revealed that both the electron tunnelling efficiency and the energy difference between the electrode Fermi level and the molecular frontier orbital also shifted due to this change in the binding preference. For example, the field effect transistor behaviour of functional SAMs can be switched between ambipolar (where the molecule can be turned on by shifting the gate voltage in either the positive or negative direction, resembling an ambipolar MOS-FET) and unipolar (where the molecule can only be turned on by shifting the gate voltage in the negative direction, resembling an n-type MOS-FET). This study demonstrates that, in addition to molecular structure engineering, molecular electronic functionalities such as tunnelling efficiency and switching behaviour can also be regulated through binding preference control during self-assembly. These findings suggest a new approach for fabricating advanced quantum technology devices.