基于石墨烯电极的蒽醌分子器件开关特性

研究了基于石墨烯电极的蒽醌分子器件的开关特性.分别选取了锯齿型和扶手椅型的石墨烯纳米带作为电极,考虑蒽醌基团在氧化还原反应下的两种构型,即氢醌(HQ)分子和蒽醌(AQ)分子,构建了双电极分子结,讨论了氧化还原反应和不同的电极结构对蒽醌分子器件开关特性的影响.研究发现,无论是锯齿型石墨烯电极还是扶手椅型石墨烯电极,HQ构型的电流都明显大于AQ构型的电流,即在氧化还原反应下蒽醌分子呈现出显著的开关特性.同时,当选用锯齿型石墨烯电极时其开关比最高能达到3125,选用扶手椅型石墨烯电极时开关比最高能达到1538.此外,当HQ构型以扶手椅型石墨烯为电极时,在0.7-0.75 V之间表现出明显的负微分电阻效应.因此该系统在未来分子开关器件领域具有潜在的应用价值.

Switching characteristics of anthraquinone molecular devices based on graphene electrodes

With the development of microelectronics and the miniaturization of electronic devices,the use of molecular materials to construct various components in electronic circuits has become a most likely development trend.Compared with silicon-based semiconductor components,molecular electronic device has the advantages of small size,high integration,low energy consumption and fast response.In recent years,more and more molecules have been used to design molecular devices such as molecular diodes,molecular switches,molecular field effect transistors and molecular memories.In this paper,sandwich structure devices based on graphene nanoribbon electrodes are constructed.The first-principles calculation method combining density functional theory and non-equilibrium Green’s function is adopted to design the molecular devices with functional characteristics.The effects of redox reactions on the electrical transport properties of molecular devices are systematically discussed.The main research contents of this paper are as follows.The switching characteristics of an anthraquinone molecular device based on graphene electrode are studied.The zigzag-edge nanoribbons and armchair-edge graphene nanoribbons are selected as electrodes.Considering the two isomers of anthraquinone(HQ)and anthraquinone(AQ)molecules in the redox reaction,the double electrode molecular junction is constructed.The effects of redox reaction and electrode structure on the switching characteristics of anthraquinone molecular devices are discussed.It is found that the current in the HQ configuration is significantly greater than that in the AQ configuration,regardless of the zigzag-edge graphene electrode or the armchair-edge graphene electrode.That is,under the redox reaction,the anthraquinone molecules show significant switching characteristics.The switching ratio of zigzag-edge graphene electrode is selected to reach a maximum of 3125,and that of armchair-edge graphene electrode is selected to maximum of 1538.In addition,when the armchair-edge graphene is used as an electrode in the HQ configuration,the negative differential resistance is obviously between 0.7 and 0.9 V.