Komoto Yuki, Isshiki Yuji, Fujii Shintaro, Nishino Tomoaki, Kiguchi Manabu
Department of Chemistry, Graduate School of Science, Tokyo Institute of Technology, 2-12-1 W4-10 Ookayama, Meguro-ku, Tokyo, 152-8551, Japan.
Chem Asian J. 2017 Feb 16;12(4):440-445. doi: 10.1002/asia.201601392. Epub 2017 Jan 27.
The electronic structure of molecular junctions has a significant impact on their transport properties. Despite the decisive role of the electronic structure, a complete characterization of the electronic structure remains a challenge. This is because there is no straightforward way of measuring electron spectroscopy for an individual molecule trapped in a nanoscale gap between two metal electrodes. Herein, a comprehensive approach to obtain a detailed description of the electronic structure in single-molecule junctions based on the analysis of current-voltage (I-V) and thermoelectric characteristics is described. It is shown that the electronic structure of the prototypical C single-molecule junction can be resolved by analyzing complementary results of the I-V and thermoelectric measurement. This combined approach confirmed that the C single-molecule junction was highly conductive with molecular electronic conductances of 0.033 and 0.003 G and a molecular Seebeck coefficient of -12 μV K . In addition, we revealed that charge transport was mediated by a LUMO whose energy level was located 0.5≈0.6 eV above the Fermi level of the Au electrode.
分子结的电子结构对其输运性质有重大影响。尽管电子结构起决定性作用，但对电子结构进行完整表征仍是一项挑战。这是因为对于被困在两个金属电极之间纳米级间隙中的单个分子，没有直接的方法来测量电子能谱。在此，描述了一种基于电流 - 电压（I - V）和热电特性分析来详细描述单分子结中电子结构的综合方法。结果表明，通过分析I - V和热电测量的互补结果，可以解析典型C单分子结的电子结构。这种联合方法证实，C单分子结具有高导电性，分子电子电导为0.033和0.003 G，分子塞贝克系数为 - 12 μV K。此外，我们发现电荷传输是由一个最低未占分子轨道（LUMO）介导的，其能级位于金电极费米能级上方0.5≈0.6 eV处。
