石墨烯电极制备及其器件应用研究

发布时间：2018-11-21 13:04

【摘要】：石墨烯是碳原子以sp2杂化轨道按蜂窝状晶格排列形成的二维单原子层结构晶体,石墨烯的独特结构以及众多优异性质使其在许多方面具有广阔的应用前景。本论文主要研究了化学气相沉积法制备的石墨烯薄膜性能,先将石墨烯薄膜与光电子器件结合制备了相关器件,再以场发射理论为基础,研究了石墨烯薄膜的场发射性能,并提出了提高场发射性能的方法。本论文主要工作分为以下三个部分:首先,利用化学气相沉积法制备了石墨烯薄膜,之后结合转移技术,将石墨烯薄膜应用到光电子器件(有机发光二极管、有机场效应晶体管、有机太阳能电池)中。通过改变转移次数,控制石墨烯薄膜的厚度,研究了石墨烯薄膜厚度对光电子器件性能的影响。实验结果表明,石墨烯薄膜厚度对光电子器件性能的影响是较为明显的,这主要是由于随着石墨烯薄膜厚度的增加,石墨烯薄膜的面电阻与透过率随之发生变化,这些参数的调控对光电子器件性能有较为直接的影响。然后,从化学气相沉积法的制备工艺参数出发,研究了制备工艺参数对石墨烯薄膜场发射性能的影响。实验结果表明沉积时间对于场发射性能的影响较为明显,沉积时间为5 min的石墨烯表现出最优异的场发射性能,其开启电场为9.8V/?m,阈值电场为13 V/?m。其原因在于沉积时间不充足无法生长成连续的石墨烯薄膜,制备的样品包含许多“石墨烯岛”边缘发射区域,即场发射点的增加导致了场发射性能的提高。最后,介绍了提高石墨烯薄膜场发射性能的方法。一是通过对石墨烯薄膜的铜箔衬底进行激光刻蚀处理,提高了其场发射性能。利用激光对铜箔表面以扫描的方式进行刻蚀处理,之后在此铜箔上生长石墨烯薄膜。通过这种方法制备的石墨烯薄膜场发射性能得到了一定的提高,沉积时间5 min的石墨烯薄膜开启电场从9.8 V/?m减小到8.8 V/?m,阈值电场从13 V/?m减小到12.2 V/?m,场增强因子也从原来的640增加到了1757。二是改变场发射方式,即研究了石墨烯薄膜的边缘场发射性能测试。利用铜箔衬底柔性特点,将制备的石墨烯卷曲成圆柱体形状,并对其进行了场发射测试。测试结果发现其场发射性能得到了较大的提高,其开启电场和阈值电场分别为3.4 V/?m和5.8 V/?m,场增强因子高达5068,最大场发射电流密度也提高了一个数量级。综上所述,本工作将CVD方法制备的石墨烯作为电极,对其应用于多种光电子器件并对其光电或电学特性进行了研究,为后续高性能器件的研制打下了基础。
[Abstract]:Graphene is a two-dimensional monoatomic crystal formed by sp2 hybrid orbitals arranged in honeycomb lattice. Because of its unique structure and many excellent properties, graphene has a broad application prospect in many fields. In this paper, the properties of graphene thin films prepared by chemical vapor deposition (CVD) were studied. Firstly, the related devices were prepared by combining graphene films with optoelectronic devices, and then the field emission properties of graphene films were studied based on field emission theory. A method to improve the field emission performance is also proposed. The main work of this thesis is as follows: firstly, graphene thin films were prepared by chemical vapor deposition, and then the graphene thin films were applied to photoelectron devices (organic light-emitting diodes, organic light-emitting diodes). There are field effect transistors, organic solar cells). The influence of the thickness of graphene film on the performance of optoelectronic devices was studied by changing the transfer times and controlling the thickness of graphene film. The experimental results show that the effect of graphene film thickness on the performance of photoelectron devices is obvious, which is mainly due to the change of surface resistance and transmittance of graphene film with the increase of graphene film thickness. The control of these parameters has a direct effect on the performance of optoelectronic devices. Then, the effect of preparation parameters on the field emission properties of graphene thin films was studied based on the process parameters of chemical vapor deposition. The experimental results show that the effect of deposition time on the field emission performance is obvious. Graphene with deposition time of 5 min exhibits the best field emission performance, with a starting electric field of 9.8 V / m and a threshold electric field of 13 V / m. The reason is that the deposition time is not sufficient to grow into continuous graphene films, and the sample contains a lot of "graphene island" edge emission region, that is, the increase of field emission point leads to the improvement of field emission performance. Finally, the methods to improve the field emission properties of graphene films are introduced. Firstly, the field emission property of graphene film is improved by laser etching of copper foil substrate. The surface of copper foil was etched by laser and then graphene film was grown on the copper foil. The field emission properties of graphene thin films prepared by this method have been improved to some extent. The opening electric field of graphene thin films with deposition time of 5 min has been reduced from 9.8 V / m to 8.8 V / m. The threshold electric field decreased from 13 V / m to 12.2 V / m, and the field enhancement factor increased from 640 to 1757. The other is to change the field emission mode, that is, to study the edge field emission performance of graphene film. The graphene was curled into a cylindrical shape by using the flexibility of copper foil substrate and the field emission measurements were carried out. The test results show that the field emission performance is greatly improved. The opening electric field and the threshold electric field are 3.4 V / m and 5.8 V / m, respectively, and the field enhancement factor is as high as 5068. The maximum field emission current density is also increased by an order of magnitude. To sum up, graphene prepared by CVD method is used as electrode in this work, and it is applied to various optoelectronic devices and its photoelectric or electrical properties are studied, which lays a foundation for the development of high performance devices in the future.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ127.11;TM914.4;TN386;TN383.1

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