Controlling the Electronic Contact at the Terpyridine/Metal Interface
Controlling the Electronic Contact at the Terpyridine/Metal Interface
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DOI：
10.1021/acs.jpcc.9b05865
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发表时间：
2019-09-05
影响因子：
3.7
通讯作者：
Karthaeuser, Silvia
中科院分区：
文献类型：
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作者：
Mennicken, Max;Peter, Sophia Katharina;Karthaeuser, Silvia
三吡啶衍生物具有丰富的配位化学性质，经常用于构建可靠的金属超分子线，是光电子或纳米电子器件的有前途的候选者。在这里，我们特别研究了三元吡啶/电极界面，这是这些有机/无机混合结构中的关键点，对器件性能至关重要。我们利用这种方法在纳米电极之间固定一个直径为13纳米的三元吡啶功能化金纳米粒子，并在纳米电极之间分离约10纳米，从而组装纳米器件。对形成的双势垒隧道结的电导测量显示，在10(-9)-10(-7)s范围内，有几个离散的电导值。通过与基于朗道尔公式估计的电导值进行比较，它们可以归因于不同的三联吡啶/电极接触几何形状。我们可以清楚地推断出，各自的三联吡啶/金属接触决定了穿过分子的隧道路径的长度，从而决定了测量到的器件电导。此外，形成独特的三联吡啶/电极接触几何形状与用碱性溶液对金纳米粒子的三联吡啶配体壳进行化学预处理有关。通过红外反射吸收光谱分析，我们发现只有用浓氨溶液进行化学处理才能有效地使三联吡啶锚基去质子化。这使得电接触到中间的吡啶环，因此通过分子的短隧道路径对应于高电导值。这些发现表明了一种控制三吡啶/金属界面接触几何形状的方法，这是基于这类分子的可靠纳米器件的先决条件。
Terpyridine derivatives reveal rich coordination chemistry and are frequently used to construct reliable metallo-supramolecular wires, which are promising candidates for optoelectronic or nanoelectronic devices. Here, we examine especially the terpyridine/electrode interface, which is a critical point in these organic/inorganic hybrid architectures and of utmost importance with respect to the device performance. We use the approach to assemble nanodevices by immobilization of single terpyridine-functionalized gold nanoparticles with a diameter of 13 nm in between nanoelectrodes with a separation of about 10 nm. Conductance measurements on the formed double-barrier tunnel junctions reveal several discrete conductance values in the range of 10(-9)-10(-7) S. They can be attributed to distinct terpyridine/electrode contact geometries by comparison with conductance values estimated based on the Landauer formula. We could clearly deduce that the respective terpyridine/metal contact determines the length of the tunneling path through the molecule and thus the measured device conductance. Furthermore, the formation of a distinct terpyridine/electrode contact geometry correlates with the chemical pretreatment of the terpyridine ligand shell of the gold nanoparticles with an alkaline solution. By applying infrared reflection absorption spectroscopy, we found that only a chemical treatment with a concentrated ammonia solution results in effective deprotonation of the terpyridine anchor group. This enables the electrical contact to the middle pyridyl ring and thus a short tunneling path through the molecule corresponding to a high conductance value. These findings indicate a way to control the contact geometry at the terpyridine/metal interface, which is a prerequisite for reliable nanodevices based on this class of molecules.