钴酞菁分子结中电子输运性质的理论研究

Electron transmission of cobalt phthalocyanine(CoPc) junction

利用半经验ExtendedH櫣ｃｋｅｌ分子轨道方法和格林函数方法来研究钴酞菁 (CoPc)分子结的电子输运性质。计算结果表明分子结 (器件 )电子输运性质对分子本身的电子结构、电极不同晶向表面、分子与电极间耦合强度、其界面的几何构型 ,对电极表面接触分子的末端原子的种类等诸多方面都有不同程度的依赖关系。对于CoPc这类弱耦合分子结而言 ,可以通过测量其I V曲线来研究分子本身的电子结构。本文的理论方法不仅可以用来描述分子器件的电子输运行为 ,还能用来研究扫描探针显微镜体系的伏安特性和扫描隧道谱。

The transmission functions of cobalt phthalocyanine (CoPc) molecules contacted between Au electrode as a function of the incoming electron energy were calculated using Extended Hückel molecular orbital methods combining with Green's function technique. The main features of transmission function of CoPc molecule absorbed on gold surface are very similar to each other, special for peak position. The transmission will change drastically via modulating the coupling strength or the terminal molecular atom metal(d Au H ) bond length, and also is sensitive to local geometry interface. The profile of transmission of CoPc molecule with or without four end hydrogen atoms are almost same, but a Fermi level shift about 1 2eV. Our results show that one can measure the conductance properties to study the energy levels of this kind of molecules.