【作者】 杨英；

【导师】 黄整；

【作者基本信息】 西南交通大学 ， 凝聚态物理， 2013， 硕士

【摘要】 近年来,以有机单分子构建光电子器件已然成为分子电子学领域的研究热点。九十年代末期,随着微电子学的实验技术的不断改进,许多实验研究组利用STM技术、光摄技术、LB膜技术、自组装技术等开展了许多分子器件的实验设计工作,例如发现小的共扼分子、单层或多层碳纳米管、大的有机分子(如DNA分子)等具有很多有用的功能器件,同时发现其特性,例如：分子开关、负微分电导、分子存储器、分子场效应管等特性。其次理论研究工作组也对分子器件的构件和电学性质进行了很多理论研究和论证报道。尽管对于分子器件的研究取得了一些重要进展,然而关于基函数的选取和电场对有机分子以及分子电子器件的电子输运机理的影响等问题还缺乏全面和深入的认识。因此,寻找不同的新功能分子器件材料并在理论上探索其的工作原理对实验提供有力的指导意义。现在,以具有离域的π电子的苯类和其衍生物为基础的芳香坏有机物作为主要的分子器件材料来研究,这类有机物都对提高电子的输运几率有贡献。而噻吩分子也具有很高的导电能力,可以作为太阳能电池的候选材料,因此本文以噻吩有机分子为研究对象和金原子团簇构建分子器件来研究其的伏安特性、电导和电子传输谱。为了更好地达到电极和自由分子的耦合作用,选用有限个S原子化学吸附于两个Au(1,1,1)原子团簇之间,这就构建了理论上的扩展分子,可以对有机分子与Au原子团簇表面的相互耦合作用进行模拟,并形成共价键同时伴有离子键。利用基于密度泛函理论和非平衡格林函数的第一性原理计算方法研究了噻吩有机分子的伏安特性,微分电导和电子输运透射谱。首先研究了3-乙基噻吩分子在选取空位和顶位不同连接条件下分子器件的电子输运性质,其次讨论了k点数对分子器件的能量和伏安特性的影响,研究表明空位比顶位更有利于电子的输运,并且随着k点数的增大,分子能量趋于收敛。最后以小型聚噻吩分子讨论了分子长度对分子器件电输运性质的影响以及在不同扭转角度下对分子器件电输运性质的影响变化。研究表明：随着分子长度的增加和扭转角度的增大使得电流减小。更多还原

【Abstract】 In the last few decades, functional electronic device construction by use of single molecule has become an increasing interest in molecule electronic. With continuous developing in experimental techniques in the late90s, many experimental groups carried out experimental research work on a number of molecular devices, using STM technology, light camera technology, LB film technology, self-assembly technology, organic molecular beam epitaxy technology. They found that some molecular devices have many useful functions, such as molecular switches, molecular memory, negative differential conductance, molecular FET characteristics. At the same time some theoretical groups have devoted to study of electrics properties of single molecules and obtained ample proofs. Although molecular electronic has made significant headway, due to lack of the molecular characteristics and electronic transport mechanism, one cannot guide experiments well. Therefore, the design and simulation of molecular devices in theory can provide theoretical guidance and reduce the twists for experiments.Now, with from the domain of electronic of benzene and its derivatives on the basis of aromatic ring as the main materials to study the molecular devices, organic matter this kind of organic matter to increases the chances of the electron transport. Thiophene molecules has a good conductivity as candidate materials of solar cell. So in this thesis, thiophene molecules are assembled with gold atoms cluster as molecular devices to study their volt-ampere characteristics, electrical and electrical, electrical and electronic transmission spectrum. In order to better achieve the electrodes and the coupling effect of free molecule, choose limited S atomic chemical adsorption on two Au (1,1,1) between groups of clusters, which comprise the so-called extended molecule, can very well simulate the mutual coupling effect on the surface of the molecules and the Au electrode, and form a covalent bond with an ionic bond.Based on density functional theory and nonequilibrium green’s function, the volt-ampere characteristics, differential conductance spectrum, and electron transportation are studied, the influences of k-point choosing to the energies and volt-ampere of the molecular devices are discussed. It is shown that the molecular energies are conregential with the increase of k-point. Secondly, the influences of the molecular length and torsion for the thiophene poymer to the electronic transportation are investigated. It shows that the electric current of the molecular device decreases with the increase of molecular length and torsion.更多还原