以石墨烯为电极的有机噻吩分子整流器的设计及电输运特性研究  

Design and electronic transport properties of organic thiophene molecular rectifier with the graphene electrodes

作　　者：俎凤霞[1] 张盼盼[1] 熊伦[1] 殷勇[1] 刘敏敏[1] 高国营[2] 

机构地区：[1]武汉工程大学理学院,武汉430205 [2]华中科技大学物理学院,武汉430074

出　　处：《物理学报》2017年第9期325-332,共8页Acta Physica Sinica

基　　金：湖北省教育厅科学研究计划(批准号:Q20151510);武汉工程大学科学研究基金(批准号:K201477)资助的课题~~

摘　　要：传统硅基半导体器件受到了量子尺寸效应的限制,发展分子电子学器件有可能解决这一难题.本文提出了由石墨烯电极和有机噻吩分子相结合构造分子器件的思想,建构了"石墨烯-噻吩分子-石墨烯"结构的分子器件,并运用非平衡态格林函数结合密度泛函理论的方法研究了其电输运特性.系统地分析了电子给体"氨基"和电子受体"硝基"两种取代基的位置对有机噻吩分子电输运的影响.计算表明,有机噻吩二聚物被"氨基"和"硝基"取代后会产生明显的负微分电阻效应和整流效应.进一步对产生这些效应的物理机制进行分析,发现氨基的位置可以调整负微分电阻的强弱,硝基的位置可以改变整流的方向.Molecular electronics offers new possibilities for continually miniaturizing the electronic devices beyond the limits of standard silicon-based technologies. There have been significant experimental and theoretical efforts to build thiophene molecular junctions and study their quantum transport properties. However, in most o~ these studies Au is used as lead material. It is well known that the fabrication of the traditional molecular device is now hindered by technological difficulties such as the oxidation of metallic contacts, and the interface instability between the organic molecule and the inorganic metallic electrodes. In this paper, we use the graphene electrodes to construct a series of thiophene-based devices. The graphene electrodes proposed in this paper are able to avoid such problems. Moreover, the stability of graphene electrodes at room temperature paves the way to studying the electron transport through a single molecule under the ambient conditions. Firstly, we design a series of molecular rectifying devices based on thiophene dimer and its derivatives, in which the hydrogen atom on the thiophene monomer is substituted with a representative electron- donating group （--NH2） and electron-withdrawing group （ NO2）. Secondly, we investigate systematically the electronic transport properties through these molecular junctions by performing the first principles calculations based on density functional theory and nonequilibrium Green＇s function. The calculated results show that these thiophene molecular devices substituted with --NH2 and --NO2 possess the rectifying behavior and negative differential resistance properties. Furthermore, we Mso find that the position of substituent group --NH2 or --NO2 has a major influence on the electronic transport properties. In order to explore the physical mechanism behind these transport properties, the electronic structures of the molecules, the transmission spectrum, and the molecular projected eigenstates are analyzed. The results reveal that the positio

关 键 词：分子电子学 非平衡格林函数 石墨烯 噻吩 

分 类 号：TM461[电气工程—电器]