基于碳纳米管及其复合材料的场发射器件的制备及其性能研究

发布时间：2018-03-21 14:24

本文选题：场发射　切入点：碳纳米管　出处：《华东师范大学》2015年博士论文　论文类型：学位论文

【摘要】：碳纳米管具有优异的电学、力学和热学性能,在场发射领域显示出良好的应用前景。但是,碳纳米管在发射点密度、发射稳定性、均匀性,以及柔性器件制备工艺的兼容性等方面还存在许多问题。碳纳米管薄膜场发射性能的改善以及薄膜制备工艺的优化是其走向产业化应用的重要一步。为了推动碳纳米管薄膜场发射器件的实用化发展,本论文以系统地改善碳纳米管薄膜的场发射性能、扩展碳纳米管薄膜场发射器件的应用范围、优化和发展柔性碳纳米管场发射器件的制备工艺为目标,分别对碳纳米管及其复合薄膜的场发射性能、低真空下碳纳米管薄膜的场发射性能以及柔性碳纳米管器件的场发射性能进行了探索性的研究。主要工作包括以下内容：(1)通过在丝网印刷制备的碳纳米管薄膜上旋涂二氧化钛溶胶,大幅度提高碳纳米管薄膜的场发射性能,包括显著降低其开启电场和阈值电场,明显提高电子发射稳定性。另外,还进一步通过控制二氧化钛溶胶反应时间和涂覆厚度实现了对碳纳米管/二氧化钛复合电极场发射性能的控制,获得了迄今为止场发射性能最佳的复合薄膜：超低的开启电场和阈值电场,优良的发射电流密度稳定性。(2)系统地研究了氧化性气体(空气)和非氧化性气体(氮气和氩气)氛围中,不同气压对丝网印刷制备的碳纳米管薄膜的场发射性能的影响。无论在氧化性气氛还是非氧化性气氛中,碳纳米管的场发射性能随着气压的上升而下降。但是碳纳米管的场发射性能在氧化性气氛中衰减的更快。针对在气体吸附、气体离子碰撞以及焦耳热等三种机制下解释了不同气氛中,气体对碳纳米管薄膜场发射性能的影响。另外,还利用二氧化钛复合的碳纳米管薄膜作为场发射阴极代替纯碳纳米管薄膜阴极,显著改善了低真空下的碳纳米管薄膜的场发射性能,拓展了碳纳米管场发射器件的应用。(3)通过石墨烯与碳纳米管的复合,形成石墨烯/碳纳米管复合场发射阴极,明显提高了碳纳米管薄膜的场发射性能。石墨烯与碳纳米管的复合,降低了碳纳米管薄膜与银衬底的接触势垒,提升了电子传输效率。另外,还通过控制复合薄膜中石墨烯的含量、对比复合薄膜的制备方法系统地优化了复合薄膜的场发射性能。(4)凭借半固化的有机硅(Polydimethylsiloxane, PDMS)柔性衬底的独特性能,通过结合真空抽滤法和简单的膜转移技术成功制备了全碳纳米管柔性场发射器件,并系统研究了器件弯曲方向和弯曲程度对柔性器件场发射性能的影响及其影响机理。
[Abstract]:Carbon nanotubes (CNTs) have excellent electrical, mechanical and thermal properties. In situ emission field, CNTs show a good prospect of application. However, CNTs are characterized by emission point density, emission stability and uniformity. The improvement of carbon nanotube film field emission performance and the optimization of film preparation process are important steps for its industrial application. The practical Development of Nanotube thin Film Field Emission Devices, The purpose of this thesis is to improve systematically the field emission performance of carbon nanotubes (CNTs) thin films, to expand the application range of CNT film field emission devices, and to optimize and develop the fabrication process of flexible CNT field emission devices. Field emission properties of carbon nanotubes and their composite films, The field emission properties of carbon nanotube thin films and the field emission properties of flexible carbon nanotube devices were investigated in low vacuum. The main work includes the following contents: 1) the carbon nanotube films prepared by screen printing. Spin coated titanium dioxide sol, The field emission properties of carbon nanotube films are greatly improved, including the significant reduction of the opening electric field and threshold electric field, and the significant improvement of the stability of electron emission. Furthermore, the field emission performance of carbon nanotube / titanium dioxide composite electrode was controlled by controlling the reaction time and coating thickness of titanium dioxide sol. The composite films with the best field emission performance up to now have been obtained: ultra-low open electric field and threshold electric field, The excellent stability of emission current density is studied systematically in the atmosphere of oxidizing gas (air) and non-oxidizing gas (nitrogen and argon). Effects of different pressure on field emission properties of carbon nanotube films prepared by screen printing. The field emission properties of carbon nanotubes decrease with the increase of atmospheric pressure. However, the field emission properties of carbon nanotubes decay more rapidly in oxidizing atmospheres. The effects of gases on the field emission properties of carbon nanotube films in different atmospheres are explained under the three mechanisms of gas ion collision and joule heat. The field emission properties of carbon nanotube films under low vacuum were improved by using titanium dioxide composite carbon nanotube film as field emission cathode instead of pure carbon nanotube film cathode. The application of carbon nanotube field emission devices is expanded. The composite field emission cathodes of graphene / carbon nanotubes are formed by the combination of graphene and carbon nanotubes. The composite of graphene and carbon nanotube reduces the contact barrier between carbon nanotube film and silver substrate and improves the electron transport efficiency. By controlling the content of graphene in the composite films, the field emission properties of the composite films were systematically optimized by comparing the preparation methods of the composite films. The unique properties of the flexible substrates of polydimethylsiloxane (PDMS) were optimized by means of semi-curable organosilicon polymethylsiloxane (PDMS). The flexible field emission devices of full carbon nanotubes (CNTs) were successfully fabricated by vacuum filtration and simple membrane transfer techniques. The effects of bending direction and bending degree on the field emission properties of flexible devices and their influencing mechanisms were systematically studied.
【学位授予单位】：华东师范大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TB33;TQ127.11

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