Al-Khaykanee Mohsin K, Ismael Ali K, Grace Iain, Lambert Colin J
Department of Physics, University of Lancaster Lancaster LA1 4YB UK
Department of Physics, College of Science, University of Babylon Babel Iraq.
RSC Adv. 2018 Jul 10;8(44):24711-24715. doi: 10.1039/c8ra04698k. eCollection 2018 Jul 9.
When a linear aromatic molecule within a nanogap is bound only to a source electrode, and an adjacent molecule is bound only to a drain electrode, the two molecules can interact pi-pi stacking, which allows electrons to flow from the source to the drain, pi-pi bonds. Here we investigate the thermoelectric properties of such junctions, using mono-thiol oligo-phenylene ethynylene (OPE3)-based molecules as a model system. For molecules which are -connected to the electrodes, we show that the Seebeck coefficient is an oscillatory function of the length of the pi-pi overlap region and exhibits large positive and negative values. This bi-thermoelectric behavior is a result of quantum interference within the junction, which behaves like a molecular-scale Mach-Zehnder interferometer. For junctions formed from molecular monolayers sandwiched between planar electrodes, this allows both hole-like and electron-like Seebeck coefficients to be realized, by careful control of electrode separation On the other hand for -connected molecules, the Seebeck coefficient is insensitive to , which may be helpful in designing resilient junctions with more stable and predictable thermoelectric properties.
当纳米间隙内的线性芳香族分子仅与源电极相连，且相邻分子仅与漏电极相连时，这两个分子可通过π-π堆积相互作用，π-π堆积使电子能够通过π-π键从源极流向漏极。在此，我们以基于单硫醇寡聚亚苯基乙炔（OPE3）的分子为模型体系，研究此类结的热电性质。对于与电极相连的分子，我们表明塞贝克系数是π-π重叠区域长度的振荡函数，并呈现出较大的正值和负值。这种双热电行为是结内量子干涉的结果，该结的行为类似于分子尺度的马赫-曾德尔干涉仪。对于夹在平面电极之间的分子单层形成的结，通过仔细控制电极间距，可实现空穴型和电子型塞贝克系数。另一方面，对于相连的分子，塞贝克系数对不敏感，这可能有助于设计具有更稳定和可预测热电性质的弹性结。
