几种有机分子的电子输运性质研究

发布时间：2018-03-12 17:33

  本文选题：分子器件　切入点：电子输运　出处：《中南林业科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：近几十年来,随着科技的不断发展,以硅材料为基础制作的电子元器件已经越来越无法满足人们的需求。对于电子元器件的要求已经不仅仅限于尺寸方面,在性能方面也需要有进一步的提升。当缩小单个电子元件的尺寸时,不仅制作工艺繁复程度及生产成本都会大幅度上涨,性能方面无法实现质的飞跃,还会受到量子力学和热力学规律的制约,使硅基材料器件的发展非常艰难。但是随着微观操控技术、微组装技术、微观观测技术和生物物理学的发展,人们不仅能对有机分子器件的结构和功能进行观测和模拟计算,还可以操控纳米尺度的单个有机分子,制作有特定功能的分子器件。这些分子器件被认为是慢慢接近尺度极限的传统电子器件的最合适的替代者。因此在实验和理论两方都吸引了越来越多的关注。本论文基于密度泛函理论与非平衡格林函数相结合的方法研究几种有机分子器件的电子输运性质。研究工作包括以下三个方面:(1)锡-酞菁装置中的自旋过滤,结果表明,锡-酞菁装置中自旋向上和自旋向下的投影态密度的峰值在0.74eV会先向费米能级附近移动,随着锡原子与酞菁分子距离的增大,峰值逐渐远离费米能级。在左右电极磁场平行配置中可以观察到由于结构重组导致自旋向下过滤转变为自旋向上的过滤。在左右电极磁场反平行配置中,在两个电极的能带匹配程度将占据锡-酞菁装置电子性质的主导地位。自旋过滤器类型转换可以通过将锡原子拉离锡-酞菁装置或翻转一个电极的磁场实现。(2)磁性原子嵌入锯齿形6,6,12石墨炔纳米带的高自旋过滤效应和半金属性研究,结果表明,当磁性原子掺杂在6、6、12-ZGYNRs天然“洞穴”时其能带会发生自旋分裂现象。特别是,由于边缘态与杂质态耦合导致边缘纳米带上碳原子的磁矩翻转,在钴掺杂的石墨炔中可观察到半金属性。而且在这种掺杂的纳米带内发现在相当宽的偏压范围内有高自旋过滤效应,为自旋电子学器件的应用提供了一种可能性。(3)研究中心分子与左右电极耦合效应对分子器件的电子输运特性的影响。主要观察非那烯分子与石墨烯纳米带所在平面的夹角为0°,30°,60°时电子输运性质的不同的表现。计算结果表明,随着偏转角度的增加,该分子器件的电压-电流特性逐渐变好。
[Abstract]:In recent decades, with the development of science and technology, the electronic components based on silicon material have been unable to meet the needs of people. There is also a need for further improvements in performance. When the size of a single electronic component is reduced, not only will the manufacturing complexity and production costs increase dramatically, but no qualitative leap in performance can be achieved. It will also be constrained by quantum mechanics and thermodynamics, making the development of silicon-based devices very difficult. But with the development of micromanipulation technology, micro-assembly technology, micro-observation technology and biophysics, Not only can the structure and function of organic molecular devices be observed and simulated, but also individual organic molecules can be manipulated on a nanoscale scale. Molecular devices with specific functions are considered to be the most suitable substitutes for traditional electronic devices which are slowly approaching the scale limit. Therefore, both experimental and theoretical aspects have attracted more and more attention. Based on density functional theory (DFT) and nonequilibrium Green's function, the electron transport properties of several organic molecular devices are studied in this paper. The results show that the peak value of projection state density of spin up and down in tin phthalocyanine unit moves first to the Fermi level at 0.74 EV, and the distance between tin atom and phthalocyanine molecule increases with the increase of the distance between tin atom and phthalocyanine molecule. The peak value is gradually away from the Fermi level. In the magnetic field parallel configuration of the left and right electrodes, it can be observed that the spin-down filter changes to the spin-upward filter due to the structural reconfiguration. In the anti-parallel configuration of the left and right electrode magnetic field, The electronic properties of tin phthalocyanine unit will be dominated by the matching degree of energy band between two electrodes. The type conversion of spin filter can be realized by pulling tin atom away from tin phthalocyanine device or flipping the magnetic field of one electrode. Study on the High spin Filtration effect and Semi-metallic Properties of Graphite Nanobelts embedded in Sawtooth 6N 6N 12 Graphite Nanoribbons, The results show that when the magnetic atom is doped in the natural "cave" of 6ZGYNRs, the spin-splitting phenomenon will occur in the energy band, especially, the magnetic moment of carbon atoms in the edge nanosphere is reversed due to the coupling of the edge state and the impurity state. Semi-metallic properties can be observed in cobalt-doped graphite acetylene, and high spin filtering effects are found in such doped nanobelts over a wide bias voltage range, This paper provides a possibility for the application of spin electronic devices.) the influence of coupling effect between central molecule and left and right electrode on electron transport characteristics of molecular devices is studied. When the angle of the plane is 0 掳~ 30 掳~ 60 掳, the properties of electron transport are different. With the increase of deflection angle, the voltage-current characteristics of the molecular device become better.
【学位授予单位】：中南林业科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O56
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本文编号：1602596