Molecular Rectification Based on Asymmetrical Molecule−Electrode Contact
Molecular Rectification Based on Asymmetrical Molecule−Electrode Contact
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DOI：
10.1021/jp905713a
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发表时间：
2010-02
影响因子：
3.7
通讯作者：
Jian-wei Zhao;Cui Yu;Nan Wang;Hongmei Liu
中科院分区：
文献类型：
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作者：
Jian-wei Zhao;Cui Yu;Nan Wang;Hongmei Liu
用密度泛函理论结合非平衡态格林函数方法研究了非对称电极−分子接触的分子整流，而不是不对称的分子取代。在基于卟啉的分子结中，我们在左侧增加了一个硫醇基团来增强电子耦合。这些接触-非对称结的输运显示出明显的整流，这意味着非对称界面修饰在分子二极管设计中是可行的。理论计算表明，在0.6~1.2V的较大偏置范围内，整流比约为2.6。我们用分子轨道能级对金属−分子−金属结中偏置电极的排列进行了解释。这突出了这样一个事实，即在评估包含单分子的纳米电结时，接触不对称是一个需要考虑的重要因素。
Instead of asymmetric molecular substitution, we investigate the molecular rectification originating from asymmetrical electrode−molecule contacts using density functional theory combined with the nonequilibrium Green’s function method. In the porphyrin-based molecular junction, we employ an additional thiol group on the left side to enhance the electronic coupling. The transportation of these contact-asymmetrical junctions shows obvious rectification, implying that the asymmetrical interface modification is feasible in the design of molecular diodes. The theoretical calculations show that the rectification ratio is about 2.6 in the large bias range from 0.6 to 1.2 V. We give an interpretation using the alignment of the molecular orbital levels to the biased electrodes in the metal−molecule−metal junction. This highlights the fact that contact asymmetry is a significant factor to be considered when evaluating nanoelectrical junctions incorporating single molecules.