Portrait of the potential barrier at metal-organic nanocontacts.
Portrait of the potential barrier at metal-organic nanocontacts.
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DOI：
10.1038/nmat2625
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发表时间：
2010-04
期刊：
影响因子：
41.2
通讯作者：
L. Vitali;G. Levita;R. Ohmann;A. Comisso;A. De Vita;K. Kern
中科院分区：
文献类型：
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作者：
L. Vitali;G. Levita;R. Ohmann;A. Comisso;A. De Vita;K. Kern
通过金属-分子接触的电子传输极大地影响了基于有机半导体的电子器件的运行和性能，是开发单分子结的分子电子学的核心。我们对这些系统中电荷注入和引出过程的理解在很大程度上依赖于我们对接触处势垒的了解。尽管在实验和理论上取得了重大进展，但单分子水平上的接触障碍仍然缺乏明确的理论基础。在这里，我们使用扫描隧道显微镜以前所未有的细节直接探测单个分子与金属电极之间的纳米接触。我们的实验表明，在亚分子尺度上有很大的变化。与铜电极结合的4-[反式-2-(吡啶-4-基乙烯基)]苯甲酸分子的局域势垒调制超过1 eV。巨型调制反映了特定分子基团与金属之间的相互作用，说明了决定界面电势的关键过程。在我们的结果的指导下，我们引入了一种新的方案来精确地局部操纵分子纳米接触的势垒。
Electron transport through metal–molecule contacts greatly affects the operation and performance of electronic devices based on organic semiconductors,,,and is at the heart of molecular electronics exploiting single-molecule junctions,,,. Much of our understanding of the charge injection and extraction processes in these systems relies on our knowledge of the potential barrier at the contact. Despite significant experimental and theoretical advances a clear rationale of the contact barrier at the single-molecule level is still missing. Here, we use scanning tunnelling microscopy to probe directly the nanocontact between a single molecule and a metal electrode in unprecedented detail. Our experiments show a significant variation on the submolecular scale. The local barrier modulation across an isolated 4-[trans-2-(pyrid-4-yl-vinyl)] benzoic acid molecule bound to a copper(111) electrode exceeds 1 eV. The giant modulation reflects the interaction between specific molecular groups and the metal and illustrates the critical processes determining the interface potential. Guided by our results, we introduce a new scheme to locally manipulate the potential barrier of the molecular nanocontacts with atomic precision.