【作者】 周军红；

【导师】 王坚；

【作者基本信息】 华南理工大学 ， 材料物理与化学， 2012， 博士

【摘要】 有机电致白光发光二极管（WOLEDs）以其既可以作为平板显示的背光源，还可以用作大面积超薄、高效率、低能耗的固态光源，同时以其简单的制作工艺，丰富、廉价的材料供应等优点引起了科学界、工业界的广泛兴趣。而基于溶液加工工艺（旋转涂覆、喷墨打印、L B成膜等）的WOLEDs更是以设备投资小、成品率高、节约材料、易于实现大面积等优点弥补了真空蒸镀工艺的不足，让WOLEDs作为一种新型节能、环保的照明器件，对缓解人类对能源日益增大的需求、控制环境的污染、实现人类社会的可持续发展起到重要的作用。为此，本文主要的研究目的就是基于溶液加工工艺，从高发光性能的白光发光体系的开发及器件结构的优化、光的萃取技术的开发及应用、大面积基板结构的设计与优化、大面积WOLEDs制备工艺的优化等角度对大面积WOLEDs在照明领域的实用化进行研究。首先，我们进行了高发光性能的白光发光体系的开发及器件结构的优化方面的工作。该项工作主要分为两个方面：一是基于共轭结构的树枝状蓝光荧光化合物（G0）掺杂磷光绿光发光配合物（Ir(mppy)3）及磷光红光发光配合物（Ir(piq)2acac）的三元发光体系。通过系列的掺杂浓度的调节，实现了高效优质的白光发光器件，其中，最大功率效率(PE)为7.7lm W-1,最大电流效率(LE)为16.9cd A-1，最大外量子效率(EQE)达到8.4%，CIE坐标为（0.312，0.332）非常接近等能白光点。该发光体系的显色指数CRI在亮度为1000cd m-2时高达90，接近理想白光。二是基于共轭结构的树枝状蓝光荧光化合物（G0）掺杂诱导聚集增强发射（AIEE）荧光黄光材料（CN DPASDB）的二元发光体系。AIEE材料在固态或聚集态的情况下通过抑制分子间的自旋而实现在高电流密度下抑制淬灭、增强发射。基于该体系我们实现了高效电致纯荧光的WOLEDs，其最大的功率效率为22lm W-1,最大外量子效率高达9.8%。其次，如何去提高外量子效率也是大面积WOLEDs是否能够成功运用于照明领域的关键。我们知道输出耦合效率大概为0.33，这意味着将近三分之二的光被限定在基板内而浪费掉了。为了解决输出耦合效率太低的问题，我们发明了一个新颖的工艺：通过对器件表面喷砂打磨使器件表面由光滑形貌变的比较粗糙，来实现改变光在玻璃空气界面的入射角的目的，从而使更多的光能够从前向方向逃逸出来。该工艺简单易于操作，效果明显。我们将该工艺运用于4inch WOLEDs中实现了最大的功率效率，电流效率，亮度、外量子效率的提高率分别为23.3%，29%，42.5%，28.9%。更重要的是该方法的运用没有引起白光发光光谱的变化。最后，对于大面积WOLEDs的实用化，好的基板是基础。所以我们在基板结构的设计方面做了很多的工作，铟锡氧化物（ITO）作为导电阳极，以其优异的光透过率及相对较好的导电能力得到广泛的使用，但是在大面积发光器件上，其导电能力还是严重不足，往往会出现电流注入困难而影响发光性能、发光不均匀等方面的问题。为了克服这些方面的问题我们通常需要在ITO上面设置一些高电导率的金属或金属氧化物线条去帮助电流的注入，这样一来就复杂化了基板的结构，对功能层的成膜均匀性、基板的制作成本等方面都带来了影响。为了找到平衡点，我们将电极从单边电极改为多边电极，将高电导率金属线的布局、宽度及间距进行了合理的调整最终成功制备出了4inch基于溶液加工工艺的有机白光照明板及基于该板组装而成的有机白光照明台灯。更多还原

【Abstract】 WOLEDs have attracted enormous attentions, due to their potential application inbacklights for panel displays and also can be used for large size, high efficiency solid statelighting sources, as well as for their advantages of simple process, abundant and cheap supplyof materials. But WOLEDs based on solution process, such as spin coating, ink jetting, andLangmuir Blodgett Film, will play an important role to alleviate the increasing demand forenergy, control environmental pollution, and to realize the sustainable development of humansociety for their advantages of cheap equipment, save materials and easy to produce full colorand large size display.As partial efforts of my Ph.D. study, I focus on the solution processes to research theapplication of WOLEDs in the lighting field at the angle of the structural design andoptimization, process optimization, development and optimization of device structures, lightextraction technology, and so on.We pay more attentions on the development and optimization of the high performancelight emitting system and device structure, which includes two aspects:Firstly, we doped the fluorescent conjugated dendrimer (G0) with RG iridium metalcomplexes with appropriate ratio. The highly properties WOLEDs were achieved, themaximum PE, LE, and EQE were7.7lm W-1,16.9cd A-1, and8.4%, respectively. The CIEcoordinates of (0.312,0.332) close to NTSC standard. The CRI value of the WOLEDsreaches90under the luminance of1000cd m-2, which is very close to the ideal white light.Secondly, we introduced a yellow emitting fluorescent aggregation induced enhancedemission (AIEE) dopant oligo(paraphenylene vinylene) derivative CN DPASDB into the hostG0. AIEE materials emerge as an alternative to solve the exciton quenching at high currentdensity, due to their enhanced emission at the aggregate state which is attributed to therestricted intramolecular rotation in the solid state or aggregate state. Based on this system,we achieved a record efficiency for fluorescent WOLEDs, which with the maximum PE andEQE reached to22lm W-1and9.8%, respectively.Hereafter, how to improve the EQE also is the key for the application of WOLEDs in thelighting field. The out coupling efficiency is only0.33, which means most of light cannotescape from the device in the forward viewing direction. To address the output coupling issue,we developed a novel process to roughen the substrate surface via sandblasting. The roughsurface will change the emitting light’s incident angle at the substrate air interface, leading tomore escaped photons in the forward viewing direction. By employing the simple, low cost sandblasting method, the maximum PE, LE, L, and EQE of the WOLEDs were enhanced23.3%,29%,42.5%, and28.9%, respectively. Moreover, the emission spectrum has noaltered caused by the rough surface.Finally, good substrate is the basis for the practical use of the large area WOLEDs.So, we have done a lot of work in the design of substrate structure. ITO has been widely usedas a conductive anode with its excellent light transmittance and good electrical conductivityability. But its applications often cause the problems of current injection difficulties andlighting non uniformity in the large size WOLEDs. In order to help the current injection, weneed to add some high conductivity metal or metal oxides lines on the ITO anode. But thismethod gave some affects to the uniformity of function layer, the cost of the substrate, and soon. So in order to solve this problem, we changed the electrode from one side to two sides,revised the Layout, width and spacing of the high conductivity metal lines. We successfullyprepared4inch WOLED and assembled organic lighting lamp.更多还原