【作者】 钱敏；

【导师】 孙卓；

【作者基本信息】 华东师范大学 ， 纳米物理学， 2012， 博士

【摘要】 纳米碳材料薄膜因其独特的结构和功能特性,成为纳米光电器件领域的研究热点之一。纳米碳管、石墨烯等纳米碳材料,具有很高的机械强度、优秀的导电性以及良好的导热性,作为理想的纳米光电材料,可广泛应用于透明导电薄膜和场发射阴极。本论文围绕纳米碳材料的制备和纳米碳材料薄膜光电器件的应用展开研究。总体目标在于研究二维纳米碳材料的新型制备方法,优化薄膜制备工艺,以研究纳米碳管、石墨烯薄膜的透明导电及场发射性能,实现纳米碳管薄膜的大屏幕场发射显示器相应的驱动系统。主要工作包括以下内容：1)首次发现脉冲激光剥离法制备二维纳米材料的实验现象,并进行了机理解释。真空中,脉冲激光作用于旋涂法制备的聚碳苯薄膜,产生等离子体羽辉,利用硅片等衬底收集羽辉中的物质并加以分析。通过控制激光能量、波长、腔体气压等因素,在衬底上可得到无定形碳、二维纳米碳片、纳米金刚石颗粒等纳米碳结构。通过分析,对实验现象进行了机理解释。利用激光剥离法制备二维纳米材料需要几个基本条件：被剥离物体表面要平整连续,激光的光子能量要小于物体内部的键能,以及适当的脉冲激光能量。利用脉冲激光制备二维纳米材料,之前未有相关报道,本工作首次发现并提出脉冲激光剥离法制备二维纳米碳片的实验现象和机理解释,为激光辅助纳米工程注入新的生机。2)首次利用脉冲激光剥离法制备石墨烯,发展了液相脉冲激光剥离法制备石墨烯及其透明导电薄膜的应用。真空中,脉冲激光作用于高定向热解石墨,产生等离子羽辉,利用硅片等衬底接收羽辉中的物质。系统分析在激光波长、腔体气压确定的条件下,通过改变激光能量,衬底上的产物依次为无定形碳、石墨烯、薄石墨片。在一定的激光能量范围内,石墨烯的纯度较高。对石墨烯的产生进行机理解释,激光对高定向热解石墨的机械作用,使得石墨表面石墨烯层间发生压缩和膨胀,从而导致表层石墨烯被剥离。液体中,被剥离的石墨烯有利于被液体收集,从而为进一步应用创造了条件。利用此方法制备的石墨烯制成的透明导电薄膜,显示出较好的透光性和导电性。3)真空抽滤法制备纳米碳管、石墨烯透明导电薄膜及特性研究。利用真空抽滤方法制备的薄膜,均匀性好、厚度可控。研究纳米碳管、石墨烯透明导电薄膜的制备、衬底转移、透明导电性能。薄膜在衬底之间的转移遵循界面能原理。真空抽滤制备的纳米碳管、石墨烯薄膜显示了较好的透光性和导电性,然而,与商业化应用要求还有一定距离,今后的研究方向在于纳米碳材料与金属、半导体材料的复合。4)真空抽滤、丝网印刷制备纳米碳管、石墨烯场发射阴极特性研究。将真空抽滤法制备的纳米碳管、石墨烯薄膜应用于场发射阴极。实验研究了不同体积纳米碳材料悬浊液制备的薄膜,对阴极形貌和场发射特性的影响,得到了最优的实验条件。与传统丝网印刷技术制备的薄膜相比,真空抽滤法制备的纳米碳管、石墨烯薄膜在开启电压、场增强因子、发光点密度分布、发射稳定性、与衬底的接触等方面都具有优势,从而对场发射阴极工艺的改进有积极意义。5)丝网印刷法制备的大屏幕纳米碳管场发射显示器的驱动电路研究。针对实验室采用丝网印刷法制备的40英寸纳米碳管场发射显示器,研究相应的驱动电路,实现了动态图像显示。二极管结构的场发射器件工作电压在300V左右。采用具有相应驱动电压的高压芯片,结合显示屏通用的低压驱动电路,实现了纳米碳管场发射显示器的专用驱动系统,得到了显示屏的动态图文显示。更多还原

【Abstract】 Carbon nanomaterials, such as carbon nanotube (CNT), graphene, have attracted much attention, because of their unique structures and extraordinary mechanical, optical, thermal and electrical properties. CNT and graphene have been widely investigated for potential applications, such as transparent conductive films and field emission cathodes.This dissertation focused on the synthesis of carbon nanomaterials and their applications in photoelectric devices. The investigation contains the novel method for the synthesis of two-dimensional carbon nanomaterial, the fabrication of carbon nanomaterial films by vacuum filtration, the transparent conductive properties of the filtered carbon films, the field emission properties of the filtered and screen-printed carbon films, and the driving system for the CNT field emission display (FED).The work mainly includes the following aspects:1) The discovery of the formation of two-dimensional nanomaterials through pulsed laser exfoliation, and the mechanism description.When the pulsed laser interacted with the spin-coated poly(phenylcarbyne) film in a vacuum chamber, the laser plume occurred and a silicon substrate was used to collect the ablated materials. By controlling the laser energy, laser wavelength and pressure, different carbon nanostructures were obtained on the silicon substrates, such as amorphous carbon, two-dimensional carbon nanosheets, diamond-like carbon. The experimental parameters for the formation of two-dimensional nanomaterials were suggested as:a plane and continuous target surface, the photon energy of the laser smaller than the bond energy in the polymer, and an appropriate laser fluence.This study reveals a novel route of forming two-dimensional carbon nanosheets by pulsed laser for the first time, and has significantly contributed to the field of laser-assisted nanotechnology.2) The discovery of the synthesis of graphene by pulsed laser exfoliation. The formation of graphene by liquid-phase pulsed laser exfoliation and its application in transparent conductive films.Few-layer graphene was formed through pulsed laser exfoliation of highly ordered pyrolytic graphite (HOPG) in a vacuum chamber. The laser interacted with the HOPQ and a silicon substrate was used to collect the ablated material in laser plume. As the laser fluence increased, different carbon phases, amorphous carbon, few-layer graphene, and thin graphite films, were obtained. The mechanism was explained as the laser-induced mechanical process leaded to the compression and expansion of HOPG surface, resulting in the exfoliation of graphene sheets.Liquid-phase pulsed laser exfoliation offers an effective way to collect the graphene. Graphene suspension was obtained and transparent conductive graphene films were fabricated by vacuum filtration.3) The fabrication and properties of transparent conductive CNT and graphene films by vacuum filtration.The film fabricated by vacuum filtration has uniform surface, and the thickness is easy to control. Transparent conductive CNT and graphene films were fabricated by vacuum filtration. The film transfer process was explained by interfacial binding energy between different materials. To further improve the transparency and conductivity of the films, effort will be put into the modification and composition of the carbon materials.4) The investigations on the electron field emission properties of CNT and graphene films fabricated by vacuum filtration and screen printing.Electron field emission properties of CNT and graphene films fabricated by vacuum filtration were studied by changing filtration volumes. A comparative study on the electron field emission properties of carbon films prepared by vacuum filtration and screen printing was carried out. Comparing with the screen-printed carbon films, filtered carbon films showed lower turn-on field, higher enhancement factor, better emission spot density, longer lifetime, and greater adhesive strength to substrates. This study reveals a potential route of the filtered carbon films as field emission cathodes. 5) The driving system for large-scale CNT FED.The driving system was designed for the40-inch CNT FED. The driving voltage for the diode-type FED is around300V. Based on digital visual interface, decoding system, field programmable gate array control system, and high voltage driving circuit, the driving system for the large-scale diode-type CNT FED was developed, and the dynamic display was realized.更多还原