Gas-sensor property of single-molecule device: F ₂ adsorbing effect

Abstract

The single thiolated arylethynylene molecule with 9,10-dihydroanthracene core (denoted as TADHA) possesses pronounced negative differential conductance (NDC) behavior at lower bias regime. The adsorption effects of F 2 molecule on the current and NDC behavior of TADHA molecular junctions are studied by applying non-equilibrium Green's formalism combined with density functional theory. The numerical results show that the F 2 molecule adsorbed on the benzene ring of TADHA molecule near the electrode can dramatically suppresses the current of TADHA molecular junction. When the F 2 molecule adsorbed on the conjugated segment of 9,10-dihydroanthracene core of TADHA molecule, an obviously asymmetric effect on the current curves induces the molecular system showing apparent rectifier behavior. However, the current especially the NDC behavior have been significantly enlarged when F 2 addition reacted with triple bond of TADHA molecule.

First-principles study of single-molecule-structure determination of dithienoborepin isomers

“…Aviram 和 Ratner 在 1974 年首次研究分子整流器件,其目的之一是实现分子尺 度的电子器件,从而推动电子器件进一步的小型化 [1] .经过半个世纪的研究和发展, 分子器件的实验和理论研究都取得了重要发现.在研究分子结的电子输运行为时, 科学家们发现了负微分电阻 [2][3][4][5][6] , 整流 [7,8] , 开关 [9,10] , 场效应管 [11,12] 等特性.与以 往的微电子器件不同的是,电子在单分子结不同能级之间传输时,由于相互干涉, 其电导会被增强或抑制,这就是单分子结电输运过程中的量子干涉效应 [13,14] .因此, 量子干涉对分子结的电子输运性质有明显的影响.以往的研究表明,锚接基团与有 机分子的连接位 [15][16][17] , 掺杂原子的取代位置 [18,19] 以及分子结构 [20] 都是影响量 子干涉效应的因素. 此外, 量子干涉效应还可以通过机械力 [21,22] 、化学环境 [23,24] 和电化学 [25][26][27] 等外界刺激 [28][29][30] 来调节.因此,利用量子干涉效应调制有机单分子 的电荷输运成为分子电子学研究的热点.在分子的不同结构位置引入基团进行钝 化,使电子在分子轨道传输过程中发生干涉,从而改变电子在结中的透射率 [31] .通 过改变分子构型来控制分子结的电导率,还可以在分子水平上制造诸如分子整流 器 [32][33][34] , 分子开关 [35,36] , 分子晶体管 [37,38] 和单分子逻辑门 [39] 等电子器件.…”

Strain?Engineering of Electronic Structure and Mechanical Switch Device for Edge Modified Net-Y Nanoribbons

“…性边界条件，在另外两个方向使用15Å的真空层(vacuum cell)来消除模型与其"像"之间的相互 作用。通过结构优化使原子间相互作用的残存力在0.01 eV/Å以下，此后，我们进行有关计算。 为了简单起见，在电子结构的所有计算结果中将费米能级EF设置为零。 对器件输运性质的计算，采用基于密度泛函理论和非平衡格林函数(NEGF) [35][36][37] 的第一性 原理方法，并在 ATK 软件包中实现，设置的相关参数与电子特性计算时相同，当自洽计算收 敛性后，计算通过器件的电流可利用类 Landauer 公式 [38][39][40] ： 米带的稳定性，而纳米带边缘氧化也是常见现象，置于空气中的纳米带极易出现这种情况 [26] 。…”

“…边缘时采用常规的方式，即一个氧原子连接一个碳原子，几何优化表明这种端接方式使结构形 变最小。当然，不同的边缘氧构型会对纳米带的电子结构产生不同的调控作用 [24] ，计算发现裸 边纳米带 AB(10)呈现金属性，若两边同时采用常规氧原子端接方式并不能打开纳米带的带隙， 合能都是负值，这表明所有纳米带的稳定性都很高。原子之间结合的方式不同，结合能的差异 会很大，与其它情况 [41,42] 进行比较，发现 AB 型纳米带有较好的能量稳定性。氢端接后纳米带 的结合能降低，这是因为纳米带边缘的悬挂键被饱和，从而提高纳米带的能量稳定性。氧端接 纳米带的结合能最低，这与氧原子的桥接方式密切相关。化学形成能是描述化学反应发生时， 生成物相对反应物的能量稳定性的重要指标 [40] 。这里，我们将 本征纳米带呈金属性，与以前的研究结果一致 [29] 。H 饱和后，纳米带的带隙被打开从而转变为 Bloch states for H-AB (10) under several typical strains, the isosurface is set as 0.1|e|Å -3 .…”

Decoding Forming Processes of Different Contact Configurations in Au- and Ag-Electrode Single-Molecule Junctions

“…The electron transport properties of molecular junctions are closely related to the structures of the functional molecules, molecule–electrode interface configurations, electrode–electrode distances, and so forth. − However, different electrode materials can also result in much different transport properties for the same functional molecule, − which are generally attributed to different mechanisms, such as different energy band structures of the electrodes, , different molecule–electrode coupling strengths, and different molecule–electrode interface configurations. ,, Due to the excellent conductivity and prominent extensibility, gold is the most commonly used electrode material in molecule junction investigations. − The conductivity of silver is higher than that of gold, so silver has also been extensively studied in molecular electronics. ,,− It is found that the conductance of ethynyl-terminated molecular junctions with silver electrodes is much higher than that of the molecular junctions with gold electrodes . However, this conductance difference is obviously not due to the different conductivities between gold and silver. − The preliminary calculations show that it may be attributed to the different contact configurations of the molecular junctions with different metal electrodes .…”