Dual conductance, negative differential resistance, and rectifying behavior in a molecular device modulated by side groups.
Dual conductance, negative differential resistance, and rectifying behavior in a molecular device modulated by side groups.
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DOI：
10.1063/1.4712615
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发表时间：
2012-05
期刊：
影响因子：
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通讯作者：
Haiqing Wan;Ying Xu;Guanghui Zhou
中科院分区：
文献类型：
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作者：
Haiqing Wan;Ying Xu;Guanghui Zhou
我们研究了一个分子器件模型的电子输运性质，该模型是由一个具有不同侧基的亚苯基乙炔基低聚物分子嵌入两个石墨烯电极之间的碳链中构建的。利用第一性原理方法，数值模拟观察到了这种分子器件的反常双电导、大峰谷比的负微分电阻（NDR）行为和明显的整流性能.通过对分子投影自洽哈密顿量、前线分子轨道（MO）和传输系数在不同外加偏压下的演化分析，揭示了双电导行为和整流性能的内在机理，即前线MO的不对称分布以及分子与电极之间的耦合作用.而负阻行为则是由于在一定偏压下导电轨道受到抑制。有趣的是，可以通过向分子中引入侧基来调节导电特性，并且可以通过在器件模型中添加不同的侧基来改善整流以及NDR行为（峰谷比）。
We investigate the electronic transport properties for a molecular device model constructed by a phenylene ethynylene oligomer molecular with different side groups embedding in a carbon chain between two graphene electrodes. Using the first-principles method, the unusual dual conductance, negative differential resistance (NDR) behavior with large peak to valley ratio, and obvious rectifying performance are numerically observed in such proposed molecular device. The analysis of the molecular projected self-consistent Hamiltonian and the evolution of the frontier molecular orbitals (MOs) as well as transmission coefficients under various external voltage biases gives an inside view of the observed results, which suggests that the dual conductance behavior and rectifying performance are due to the asymmetry distribution of the frontier MOs as well as the corresponding coupling between the molecule and electrodes. But the NDR behavior comes from the conduction orbital being suppressed at certain bias. Interestingly, the conduction properties can be tuned by introducing side groups to the molecule and the rectification as well as the NDR behavior (peak to valley ratio) can be improved by adding different side groups in the device model.