From single-molecule contacts to well-defined molecular ensemble contacts: Influence of intermolecular interactions onto the electronic transport

在这个项目中，我们将研究分子系综结的电子输运性质，在分子系综结中，小分子平行地接触到金属电极。在大多数情况下，它们的输运性质不能直接从同一物种的单分子结的性质中推断出来。这种差异的可能原因包括内在属性(分子相互作用)以及外部原因，如分子水平上接触几何的差异。虽然已经开发了几种能够以统计方式和在单个分子基础上研究单分子输运的技术，但还没有真正可靠、可扩展和通用的方法来研究小分子系综的输运。这种方法的缺乏阻碍了对内在效应的系统研究，这些内在效应最近引起了理论方面的极大兴趣。人们的兴趣来自于中小型分子系综在分子电子学中的高应用潜力，因为它们不太容易受到单个原子排列造成的伪影，作为单分子结具有较低的电阻，但仍然结合了非常小的尺寸和丰富的功能的优点。申请者DM最近开发了在纵横制结构中制造分子集成接触的新工艺，其连接面积从大约50 nm x 50 nm到数百平方微米。这些技术已经成功地应用于形成几个纳米厚度的导电和半导体聚合物薄层的结。我们建议进一步发展交叉杆技术，用于分子电子学中分子物种的自组装单分子膜的应用。

In this project we will study the electronic transport properties of molecular ensemble junctions, in which small molecules are contacted to metal electrodes in a parallel arrangement. In most cases their transport properties cannot straightforwardly be deduced from those of single-molecule junctions of the same species. Possible reasons for this difference include intrinsic properties (molecular interactions) as well as extrinsic reasons, like differences in the contacts geometry on the molecular level. While several techniques have been developed that enable to study the transport through single molecules, both in a statistical manner and on an individual molecular basis, no really reliable, scalable, and versatile method for the study of the transport through small molecular ensembles does exist. This methodological lack hampers systematic studies of the intrinsic effects that have recently attracted much interest from the theoretical side. The interest is driven by the high application potential of small to medium size molecular ensembles in molecular electronics, because they are less prone to artefacts caused by individual atomic arrangements, have lower resistance as single-molecule junctions but still combine the advantages of very small size and rich functionality. The applicant DM recently developed new processes for the fabrication of molecular ensemble contacts in crossbar architecture, with junction areas ranging from approximately 50 nm x 50 nm to several hundred square micrometers. The techniques have been successfully applied for the formation of junctions of thin conducting and semiconducting polymer layers of several nanometer thickness. We propose to further develop the crossbar technique for the application of self-assembled monolayers of molecular species to be used in molecular electronics.