Selective Anchoring Groups for Molecular Electronic Junctions with ITO Electrodes.
Selective Anchoring Groups for Molecular Electronic Junctions with ITO Electrodes.
复制标题
ITO 电极分子电子结的选择性锚定基团。
DOI：
10.1021/acssensors.0c02205
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发表时间：
2021
期刊：
影响因子：
8.9
通讯作者：
Planje IJ
中科院分区：
文献类型：
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作者：
Planje IJ
氧化铟锡(ITO)是一种很有吸引力的单分子电子学衬底，因为它在保持导电性的同时是透明的。尽管它以前曾被用作单分子电学研究中的接触电极，但这些研究仅限于使用羧酸末端基团将分子导线结合到ITO衬底上。因此，有必要研究具有与ITO有效结合的潜力的其他锚基。为此，我们研究了一系列具有不同表面结合基团的八甲烷或类甲苯分子导线的单分子电导。我们首先使用金-分子-金结来确定ITO选择性的有希望的靶标。然后，我们评估了羧酸、氰基丙烯酸和方吡啶与ITO结合并促进分子异质结形成的倾向和选择性。我们发现，四方吡啶两性离子在金表面上表现出与ITO结合的良好的选择性，接触电阻率与羧酸相当。这些单分子实验还得到了X射线光电子能谱、石英晶体微天平、接触角测定和原子力显微镜纳米光刻的表面化学表征的补充。最后，我们报道了第一次涉及ITO电极的密度泛函理论计算，模拟了ITO-分子-金异质结中的电荷输运。
Indium tin oxide (ITO) is an attractive substrate for single-molecule electronics since it is transparent while maintaining electrical conductivity. Although it has been used before as a contacting electrode in single-molecule electrical studies, these studies have been limited to the use of carboxylic acid terminal groups for binding molecular wires to the ITO substrates. There is thus the need to investigate other anchoring groups with potential for binding effectively to ITO. With this aim, we have investigated the single-molecule conductance of a series of eight tolane or “tolane-like” molecular wires with a variety of surface binding groups. We first used gold–molecule–gold junctions to identify promising targets for ITO selectivity. We then assessed the propensity and selectivity of carboxylic acid, cyanoacrylic acid, and pyridinium-squarate to bind to ITO and promote the formation of molecular heterojunctions. We found that pyridinium squarate zwitterions display excellent selectivity for binding to ITO over gold surfaces, with contact resistivity comparable to that of carboxylic acids. These single-molecule experiments are complemented by surface chemical characterization with X-ray photoelectron spectroscopy, quartz crystal microbalance, contact angle determination, and nanolithography using an atomic force miscroscope. Finally, we report the first density-functional theory calculations involving ITO electrodes to model charge transport through ITO–molecule–gold heterojunctions.