微纳结构柔性有机发光器件的光调控研究

发布时间：2018-10-20 12:41

【摘要】：近年来,随着可穿戴电子产品的问世(如智能手表、手环等),包括弯曲OLED显示和照明产品的不断推出(主要来自LG Display、LG Chemistry),柔性OLED(FOLED)越来越成为人们关注的焦点。所谓柔性OLED,就是基于柔性基板(PET、PC或者PEN等)的有机电致发光器件,相比于传统的LCD和LED,除了具有自发光、广色谱、轻薄等特点,FOLED更能显示出有机材料在柔性可穿戴领域方面应用的优势。但是,如果要将FOLED更快地推向市场,除了要解决良率问题外,更重要的是,还要从根源上去解决其发光效率以及稳定性的问题。所以,FOLED器件的研发和生产还有很大的拓展空间,例如:如何提高FOLED器件的发光效率、如何更方便地引入内光萃取结构、以及延长OLED的使用寿命等问题,本论文主要围绕柔性电致发光器件(FOLED)的光取出和空穴注入层修饰开展了研究工作,分别引入周期和准随机性的纳米结构,以及复合空穴注入层,进一步研究了不同光萃取结构对于器件性能的影响,最终有效的提升了器件的发光效率和稳定性。具体研究内容和主要成果如下:1.溶液法MoOx:Au NPs复合连接层在器件中的引入及性能研究。将溶液法合成的氧化钼(MoOx)前驱体和柠檬酸法合成的纳米金(Au,Diameter of 20nm)粒子混合在一起,作为复合空穴注入层(HIL)应用到OLED中。制备了结构为ITO/MoOx:Au NPs/NPB/Alq3/LiF/Al的OLED器件,利用氧化钼的可靠功函数和金粒子的表面等离子体效应,最终实现了驱动电压较低、发光效率较高以及稳定性较好的OLED器件。2.利用纳米软压印技术,在FOLED的空穴注入层PEDOT:PSS压印准随机蛾眼结构,和周期性的一维、二维光栅相比,准随机蛾眼结构对于FOLED的光调控作用最佳(相对于标准器件,有近50%的外量子效率EQE的提升),无论是对于光取出效率、光谱角度稳定性,还是R、G、B三色的萃取广谱性。结合FDTD远场模拟以绿光FOLED为例,相比于flat无结构的器件,基于蛾眼器件的效率提升和角度稳定性效果最佳,而周期性光栅由于布拉格衍射会导致光谱的选择性和角度上的依赖性。3.后续,基于柔性器件ITO-free的考虑和之前PEDOT:PSS作为空穴注入层的工作,我们又研究了在结构化UV/PET基底上引入高导电PEDOT:PSS作为正极,然后制作FOLED。通过文献调研,通过添加剂和后处理两种方法来提高PEDOT:PSS的导电率,最高可达到2500 S cm-1。但是,由于PEDOT:PSS的吸水性,其导电性不能保持稳定。通过具体器件的应用,以Flat UV的高导电PEDOT:PSS为标准器件,具有UV结构的器件在纳米微结构的光萃取作用下,效率上会有显著的提高,但器件的寿命还是大的问题,会通过后续的工作进一步改善。
[Abstract]:In recent years, with the advent of wearable electronic products (such as smart watches, bracelets, etc.), including the continuous introduction of curved OLED display and lighting products (mainly from LG Display,LG Chemistry), flexible OLED (FOLED) has become the focus of more and more attention. The so-called flexible OLED, is an organic electroluminescent device based on flexible substrate (PET,PC, PEN, etc.). Compared with the traditional LCD and LED, it not only has self-luminescence, but also has wide chromatography. Because of its lightness, FOLED can show the advantages of organic materials in flexible wearable applications. However, if we want to bring FOLED to market more quickly, we should not only solve the problem of yield, but also solve the problem of luminous efficiency and stability. Therefore, the research and production of FOLED devices still have a lot of space to expand. For example, how to improve the luminescence efficiency of FOLED devices, how to introduce the internal light extraction structure more conveniently, and how to extend the service life of OLED, etc. In this thesis, the photoluminescence and hole injection layer modification of flexible electroluminescent devices (FOLED) is studied, introducing periodic and quasi-random nanostructures, as well as composite hole injection layers, respectively. The effects of different optical extraction structures on the performance of the devices were further studied, and the luminescence efficiency and stability of the devices were improved effectively. The specific research contents and main results are as follows: 1. Study on the introduction and performance of MoOx:Au NPs Composite bonding layer in the device by solution method. The molybdenum oxide (MoOx) precursor synthesized by solution method and the nano-gold (Au,Diameter of 20nm) particles synthesized by citric acid method were mixed together and applied to OLED as a composite hole implantation layer (HIL). OLED devices with ITO/MoOx:Au NPs/NPB/Alq3/LiF/Al structure were fabricated. Using the reliable work function of molybdenum oxide and the surface plasma effect of gold particles, OLED devices with lower driving voltage, higher luminescence efficiency and better stability were achieved. 2. Using nano-soft imprint technique, PEDOT:PSS imprint quasi-random moth eye structure is injected into the hole of FOLED. Compared with periodic one-dimensional and two-dimensional grating, quasi-random moth eye structure has the best effect on the light regulation of FOLED (relative to standard device). There are nearly 50% enhancement of external quantum efficiency (EQE), both for light extraction efficiency, spectral angle stability, and extraction broad-spectrum properties of RG GnB trichrome. Combined with FDTD far-field simulation, the green light FOLED is taken as an example. Compared with the unstructured device of flat, the efficiency and angle stability of the device based on moth eye are the best. The periodic grating, due to Bragg diffraction, leads to spectral selectivity and angular dependence. 3. 3. Subsequently, based on the consideration of flexible device ITO-free and the previous work of PEDOT:PSS as hole injection layer, we also study the introduction of highly conductive PEDOT:PSS as positive electrode on structured UV/PET substrate, and then fabricate FOLED.. Through literature investigation, the conductivity of PEDOT:PSS can be increased by two methods: additive and post-treatment. The maximum conductivity of PEDOT:PSS can be as high as 2500 S cm-1.. However, the conductivity of PEDOT:PSS is not stable due to its water absorption. Through the application of specific devices, the high conductive PEDOT:PSS of Flat UV is taken as the standard device, and the efficiency of the devices with UV structure can be greatly improved by the photoextraction of nano-microstructures, but the lifetime of the devices is still a big problem. Will be further improved through follow-up work.
【学位授予单位】：苏州大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN383.1

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