不对称末端基团对分子结输运性质的影响:第一性原理的研究

Effect of asymmetric terminal groups on the transport properties of molecule junctions:a first-principles study

利用非平衡格林函数和密度泛函理论(NEGF-DFT)相结合的方法,研究了苯基分子通过不同端基对称或不对称锚定在Au(100)电极上的单分子量子输运计算。在所考虑的4种结构中,C_(6)H_(5)S的电子耦合要略强于苯硫酚,由于—S作为末端基团比—SH提供了更多的自由电子,这导致了显著的电流整流效应,但响应的稳定性比苯硫酚分子差。苯硫酚分子在0.5V以上的外加电压下,在非对称性、非线性和响应性方面表现出良好的二极管效应,虽然只有一个H原子的差异,但却表现出不同的性质。苯硫酚分子的结构及其二极管特性有利于成为界面改性材料,提高器件的光电性能。

Single-molecule quantum transport calculations were investigated using non-equilibrium Green's function method combined with the density functional theory(DEF-NEGF)for phenyl molecules symmetrically or asymmetrically anchored to Au(100)electrodes via different terminal groups.Among the considered four structures,the electronic coupling of C_(6)H_(5)S was slightly stronger than that of thiophenol.Because the-S as terminal group provided more free electrons than-SH,this resulted in significant current rectification effect,but the corresponding stability was poorer than that of thiophenol molecule.Thiophenol molecules showed good diode parameters in terms of asymmetry,nonlinearity and responsiveness at above 0.5V applied voltage.Although there was only one H atom difference,the thiophenol and C_(6)H_(5)S molecular exhibited different properties.The structure and diode characteristics of thiophenol molecule were conducive to become interface modification materials and improve the photoelectric performance of devices.