Molecular electronics is to study electrical transport in individual or single layer of molecular materials. One of the central focuses of this field is to build clear connection between the transport properties and the electronic structures of molecular junctions. In particular, the offset of the Fermi level relative to the appropriate frontier molecular orbital and the electrode−molecule coupling strength (level width) are recognized as two main factors that determine the electrical properties of a typical molecular junction. We use conducting probe atomic force microscopy to contact small numbers of molecules and to test their electrical properties. Based on an analytical single level model, derived from the Landauer formula, we are able to extract the effective tunneling barrier and molecule-electrode interface coupling from experimental current-voltage traces. We are interested in how the current-voltage characteristics of these molecular junctions depend on molecular size, bonding and functional group architecture, and the nature of the electrode-molecule contacts. We then analyze the impacts of these variables on the performance and electronic structure of the devices. Our study not only provides insights on molecular device physics, but also allows for improved device optimization in order to obtain desired electrical behaviors.

分子电子学研究单个或单层分子材料的电荷传输特性。该领域的一个关键课题是将传输特性与分子结的电子态结构清楚的关联起来。在电子态结构方面，费米能级到电荷传输轨道的距离与电极-分子间的耦合强度(轨道半峰宽)被认为两个决定电学性能主要因素。我们将使用导电原子力显微镜技术，测量少量分子的电学特性，并采用基于朗道公式的单轨道分析模型相，从实验测量得到的电流-电压曲线上获取电荷有效隧穿势磊与电极-分子耦合强度。我们的研究兴趣包含分子尺寸、分子化学键与功能团、分子与电极间的接触方式如何影响器件的电流-电压特性。然后分析这些因素对器件性能与电子态结构的影响。该研究的目的是不仅描绘分子电子学器件的物理图画，同时有利于我们提高器件的优化程度以获得理想的电学行为。