Department of Chemistry, Xi'an-Jiaotong Liverpool University, Suzhou, Jiangsu 215123, China.
Nanoscale. 2016 Aug 14;8(30):14507-13. doi: 10.1039/c6nr03807g. Epub 2016 Jul 14.
Graphene-based electrodes are attractive for single-molecule electronics due to their high stability and conductivity and reduced screening compared with metals. In this paper, we use the STM-based matrix isolation I(s) method to measure the performance of graphene in single-molecule junctions with one graphene electrode and one gold electrode. By measuring the length dependence of the electrical conductance of dicarboxylic-acid-terminated alkanes, we find that the transport is consistent with phase-coherent tunneling, but with an attenuation factor of βN = 0.69 per methyl unit, which is lower than the value measured for Au-molecule-Au junctions. Comparison with density-functional-theory calculations of electron transport through graphene-molecule-Au junctions and Au-molecule-Au junctions reveals that this difference is due to the difference in Fermi energies of the two types of junction, relative to the frontier orbitals of the molecules. For most molecules, their electrical conductance in graphene-molecule-Au junctions is higher than that in Au-molecule-Au junctions, which suggests that graphene offers superior electrode performance, when utilizing carboxylic acid anchor groups.
基于石墨烯的电极由于其高稳定性、导电性和与金属相比的屏蔽作用降低，在单分子电子学中很有吸引力。在本文中，我们使用基于 STM 的矩阵隔离 I(s)方法来测量具有一个石墨烯电极和一个金电极的单分子结中石墨烯的性能。通过测量二酸封端烷烃的电导随长度的变化，我们发现输运与相位相干隧穿一致，但衰减因子βN = 0.69 每甲基单元，低于 Au-分子-Au 结测量的值。与通过石墨烯-分子-Au 结和 Au-分子-Au 结的电子输运的密度泛函理论计算的比较表明，这种差异是由于两种结的费米能级相对于分子的前沿轨道的差异造成的。对于大多数分子，它们在石墨烯-分子-Au 结中的电导率高于 Au-分子-Au 结中的电导率，这表明当利用羧酸锚定基团时，石墨烯提供了优越的电极性能。
