中国物理B ›› 2022, Vol. 31 ›› Issue (7): 77303-077303.doi: 10.1088/1674-1056/ac4cbf

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Effect of crystallographic orientations on transport properties of methylthiol-terminated permethyloligosilane molecular junction

Ming-Lang Wang(王明郎), Bo-Han Zhang(张博涵), Wen-Fei Zhang(张雯斐), Xin-Yue Tian(田馨月), Guang-Ping Zhang(张广平), and Chuan-Kui Wang(王传奎)   

  1. School of Physics and Electronics, Shandong Normal University, Jinan 250358, China
  • 收稿日期:2021-11-11 修回日期:2022-01-12 接受日期:2022-01-19 出版日期:2022-06-09 发布日期:2022-07-19
  • 通讯作者: Ming-Lang Wang, Chuan-Kui Wang E-mail:wangminglang@sdnu.edu.cn;ckwang@sdnu.edu.cn
  • 基金资助:
    Project supported by the Shandong Provincial Natural Science Foundation, China (Grant No. ZR2019PA022) and the National Natural Science Foundation of China (Grant No. 21933002).

Effect of crystallographic orientations on transport properties of methylthiol-terminated permethyloligosilane molecular junction

Ming-Lang Wang(王明郎), Bo-Han Zhang(张博涵), Wen-Fei Zhang(张雯斐), Xin-Yue Tian(田馨月), Guang-Ping Zhang(张广平), and Chuan-Kui Wang(王传奎)   

  1. School of Physics and Electronics, Shandong Normal University, Jinan 250358, China
  • Received:2021-11-11 Revised:2022-01-12 Accepted:2022-01-19 Online:2022-06-09 Published:2022-07-19
  • Contact: Ming-Lang Wang, Chuan-Kui Wang E-mail:wangminglang@sdnu.edu.cn;ckwang@sdnu.edu.cn
  • Supported by:
    Project supported by the Shandong Provincial Natural Science Foundation, China (Grant No. ZR2019PA022) and the National Natural Science Foundation of China (Grant No. 21933002).

摘要: The understanding of the influence of electrode characteristics on charge transport is essential in the field of molecular electronics. In this work, we investigate the electronic transport properties of molecular junctions comprising methylthiol-terminated permethyloligosilanes and face-centered crystal Au/Ag electrodes with crystallographic orientations of (111) and (100), based on the ab initio quantum transport simulations. The calculations reveal that the molecular junction conductance is dominated by the electronic coupling between two interfacial metal-S bonding states, which can be tuned by varying the molecular length, metal material of the electrodes, and crystallographic orientation. As the permethyloligosilane backbone elongates, although the σ conjugation increases, the decreasing of coupling induced by the increasing number of central Si atoms reduces the junction conductance. The molecular junction conductance of methylthiol-terminated permethyloligosilanes with Au electrodes is higher than that with Ag electrodes with a crystallographic orientation of (111). However, the conductance trend is reversed when the electrode crystallographic orientation varies from (111) to (100), which can be ascribed to the reversal of interfacial coupling between two metal-S interfacial states. These findings are conducive to elucidating the mechanism of molecular junctions and improving the transport properties of molecular devices by adjusting the electrode characteristics.

关键词: molecular electronics, crystallographic orientations, non-equilibrium Green's function

Abstract: The understanding of the influence of electrode characteristics on charge transport is essential in the field of molecular electronics. In this work, we investigate the electronic transport properties of molecular junctions comprising methylthiol-terminated permethyloligosilanes and face-centered crystal Au/Ag electrodes with crystallographic orientations of (111) and (100), based on the ab initio quantum transport simulations. The calculations reveal that the molecular junction conductance is dominated by the electronic coupling between two interfacial metal-S bonding states, which can be tuned by varying the molecular length, metal material of the electrodes, and crystallographic orientation. As the permethyloligosilane backbone elongates, although the σ conjugation increases, the decreasing of coupling induced by the increasing number of central Si atoms reduces the junction conductance. The molecular junction conductance of methylthiol-terminated permethyloligosilanes with Au electrodes is higher than that with Ag electrodes with a crystallographic orientation of (111). However, the conductance trend is reversed when the electrode crystallographic orientation varies from (111) to (100), which can be ascribed to the reversal of interfacial coupling between two metal-S interfacial states. These findings are conducive to elucidating the mechanism of molecular junctions and improving the transport properties of molecular devices by adjusting the electrode characteristics.

Key words: molecular electronics, crystallographic orientations, non-equilibrium Green's function

中图分类号:  (Electronic transport in nanoscale materials and structures)

  • 73.63.-b
73.40.-c (Electronic transport in interface structures) 31.15.at (Molecule transport characteristics; molecular dynamics; electronic structure of polymers)