The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan.
Sci Rep. 2017 Mar 10;7:44276. doi: 10.1038/srep44276.
Molecular junction is a chemically-defined nanostructure whose discrete electronic states are expected to render enhanced thermoelectric figure of merit suitable for energy-harvesting applications. Here, we report on geometrical dependence of thermoelectricity in metal-molecule-metal structures. We performed simultaneous measurements of the electrical conductance and thermovoltage of aromatic molecules having different anchoring groups at room temperature in vacuum. We elucidated the mutual contributions of vacuum tunnelling on thermoelectricity in the short molecular bridges. We also found stretching-induced thermoelectric voltage enhancement in thiol-linked single-molecule bridges along with absence of the pulling effects in diamine counterparts, thereby suggested that the electromechanical effect would be a rather universal phenomenon in Au-S anchored molecular junctions that undergo substantial metal-molecule contact elongation upon stretching. The present results provide a novel concept for molecular design to achieve high thermopower with single-molecule junctions.
分子结是一种化学定义明确的纳米结构，其离散的电子态有望提高适合能量收集应用的热电优值。在这里，我们报告了金属-分子-金属结构中热电性质的几何依赖性。我们在真空中室温下对具有不同锚固基团的芳香族分子进行了电导率和热电压的同步测量。我们阐明了真空隧道效应对短分子桥中热电性质的相互贡献。我们还发现硫醇连接的单分子桥中存在拉伸诱导的热电电压增强，而在二胺对应物中则不存在拉伸效应，这表明在经受显著金属-分子接触伸长的 Au-S 锚固分子结中，机电效应将是一个相当普遍的现象。本研究结果为实现具有单分子结的高热功率提供了一种新的分子设计概念。
