Wang Yudi, Pan Haoyang, Lin Dongying, Li Shi, Wang Yongfeng, Sanvito Stefano, Hou Shimin
Key Laboratory for the Physics and Chemistry of Nanodevices, School of Electronics, Peking University, Beijing 100871, China.
Centre for Nanoscale Science and Technology, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China.
Phys Chem Chem Phys. 2022 Sep 14;24(35):21337-21347. doi: 10.1039/d2cp02318k.
In molecular electronics, electrode-molecule anchoring strategies play a crucial role in the design of stable and high-performance functional single-molecule devices. Herein, we employ aromatic pyrazine as anchors to connect a central anthracene molecule to carbon electrodes including graphene and armchair single-walled carbon nanotubes (SWCNTs), and theoretically investigate their atomic structures and electronic transport properties. These molecular junctions can be constructed condensation reactions of the central molecules terminated with -phenylenediamines with -quinone-functionalized nanogaps of graphene and SWCNT electrodes. With two direct C-N covalent bonds connecting the central molecule site-selectively to carbon electrodes in a coplanar way, pyrazine anchors are advantageous for forming stable and structurally well-defined molecular junctions, being expected to reduce the uncertainty about the electrode-molecule linkage motifs. The junction transport is highly efficient due to the coplanar geometry and the ensuing strong π-type molecule-electrode electronic coupling. Furthermore, our calculations show that molecular junctions with pyrazine anchors and carbon electrodes are usually n-type electronic devices; upon hydrogenation of pyridinic nitrogen atoms, the device polarity can be tuned to p-type, indicating that the pyrazine anchors can also serve as a powerful platform for tailoring the polarity of charge carriers in carbon-electrode molecular electronic devices.
在分子电子学中，电极 - 分子锚定策略在稳定且高性能的功能性单分子器件设计中起着关键作用。在此，我们采用芳族吡嗪作为锚定基团，将中心蒽分子连接到包括石墨烯和扶手椅型单壁碳纳米管（SWCNT）在内的碳电极上，并从理论上研究它们的原子结构和电子输运性质。这些分子结可以通过用 - 苯二胺封端的中心分子与石墨烯和SWCNT电极的 - 醌官能化纳米间隙的缩合反应来构建。通过两个直接的C - N共价键以共面方式将中心分子位点选择性地连接到碳电极，吡嗪锚定基团有利于形成稳定且结构明确的分子结，有望减少电极 - 分子连接基序的不确定性。由于共面几何结构以及随之而来的强π型分子 - 电极电子耦合，结传输效率很高。此外，我们的计算表明，具有吡嗪锚定基团和碳电极的分子结通常是n型电子器件；吡啶氮原子氢化后，器件极性可调整为p型，这表明吡嗪锚定基团也可以作为调整碳电极分子电子器件中电荷载流子极性的有力平台。
