Connectivity dependent thermopower of bridged biphenyl molecules in single-molecule junctions
Connectivity dependent thermopower of bridged biphenyl molecules in single-molecule junctions
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DOI：
10.1039/d0nr04001k
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发表时间：
2020-07-21
期刊：
影响因子：
6.7
通讯作者：
Lambert, Colin J.
中科院分区：
文献类型：
--
作者：
Grace, Iain M.;Olsen, Gunnar;Lambert, Colin J.
我们报告对黄金的测量|单分子|金结，使用改进的扫描隧道显微镜-断裂结（STM-BJ）技术，对一系列桥连联苯分子的塞贝克系数和电导进行了测量，这些联苯分子与吡啶基锚基团具有亚连接性.这些数据与之前报道的对位连接类似物的研究进行了比较。与紧束缚模型一致，该系列的电导相对较低，对桥连基团的性质敏感，而在该系列中，电导较高，对桥连基团的存在相对不敏感。这种灵敏度的差异是由于非桥连芳族核的π系统中存在破坏性量子干涉，而桥连基团的存在在不同程度上减轻了这种干扰。更准确地说，间位连接分子的塞贝克系数在-6.1 μ V·K（-1）~-14.1 μ V·K（-1）之间变化，而对位连接分子的塞贝克系数在-5.5 μ V·K（-1）~-9.0 μ V·K（-1）之间变化。
We report measurements on gold|single-molecule|gold junctions, using a modified scanning tunneling microscope-break junction (STM-BJ) technique, of the Seebeck coefficient and electrical conductance of a series of bridged biphenyl molecules, withmetaconnectivities to pyridyl anchor groups. These data are compared with a previously reported study ofpara-connected analogues. In agreement with a tight binding model, the electrical conductance of themetaseries is relatively low and is sensitive to the nature of the bridging groups, whereas in theparacase the conductance is higher and relatively insensitive to the presence of the bridging groups. This difference in sensitivity arises from the presence of destructive quantum interference in the pi system of the unbridged aromatic core, which is alleviated to different degrees by the presence of bridging groups. More precisely, the Seebeck coefficient ofmeta-connected molecules was found to vary between -6.1 mu V K(-1)and -14.1 mu V K-1, whereas that of thepara-connected molecules varied from -5.5 mu V K(-1)and -9.0 mu V K-1.