高效旋涂有机发光二极管的研究

发布时间：2018-08-30 12:59

【摘要】：有机发光二极管(OLED)由于具有超轻薄、低成本、低功耗、宽视角、全固化、白发光、驱动电压低及可实现柔性显示等诸多突出的性能,因而成为很有前途的新一代的平板显示技术。为了提高载流子的注入,降低驱动电压,提高电子和空穴的复合几率,减小光损失等,OLED目前的研发工作主要集中在新型发光材料和传输材料的开发,新颖器件结构与制造工艺的探索以及器件物理的研究等方面。有机小分子OLED器件一般采用真空蒸发沉积,但是该成膜法由于受真空腔体尺寸的限制,制备较大面积的OLED器件受到了限制,且较难精确控制掺杂比例,特别是较低的浓度掺杂。溶液旋涂法则可以有效改善这方面的缺点,通过将旋涂和蒸镀两种工艺结合,可以集中两种薄膜制备工艺的优点,使器件性能达到最优。为改进单一材料性能某方面存在的不足或缺陷,采用有机无机杂化手段制备了有效的杂化电荷注入层,由掺杂导致的电荷转移效应,可改善OLED器件的注入特性。在有机材料方面,选取有机酸、或者有机碱与其他酸和碱反应形成的有机盐(TS-CuPC)。无机盐方面,选取一些金属氧化物如三氧化钼(Mo O3),因为它们都可以用溶液法的方法制备成膜,因而是一种非常环保、低成本的技术。此外,通过UV/vis,XPS分析,发现在近红外区域有电荷转移现象,可用于制备近红外光电器件。在器件方面,基于有机无机杂化电荷注入层的器件不仅驱动电压低,而且效率相对于单一材料作为电荷注入的器件要高。通过变温J-V特性测试,发现OLEDs中空穴注入的增强是由于ITO侧的空穴注入势垒降低,这与肖特基热发射机理一致。ITO侧有效的功函数修饰通过UPS分析也得到了进一步的确认。此外为解决荧光内量子效率不超过25%的问题,在前期的研究中我们发现嘧啶型的配体由于其很好的热稳定性和形态稳定性,是一个非常好的基体材料。基于嘧啶配体的Ir红光配合物,可以取得超过28%的外量子效率。在此基础上,我们以嘧啶配体为中心,引入另一个辅助配体2,5-dimethylhexane-3,4-dione,合成了可用于旋涂的红光材料,制备的器件流明效率可以达到27.2 cd A-1,结合另一种经典蓝光磷光材料FIrpic制备的两色白光器件,效率可达28.9 cd A-1,并且取得了很好的标准的国际显色指数(CIE)(0.45,0.41)。从生理学的角度来看,这是一个非常适合人类照明的暖白色光源。基于我们合成的新型红光磷光材料,由于其高的内量子效率,制备手段简单,器件制作成本低廉等优点,可以广泛地应用于高效旋涂器件的制备。
[Abstract]:Organic light-emitting diode (OLED) has many outstanding properties such as ultra-thin, low cost, low power consumption, wide angle of view, full curing, white luminescence, low driving voltage and flexible display, etc. As a result, it has become a promising new generation of flat panel display technology. In order to improve the carrier injection, reduce the driving voltage, increase the recombination probability of electron and hole, reduce the light loss and so on, the current research and development work of OLED is mainly focused on the development of new luminescent materials and transmission materials. The research of novel device structure and manufacturing process and the research of device physics. Organic small molecule OLED devices are usually deposited by vacuum evaporation. However, due to the limitation of the vacuum cavity size, the fabrication of large area OLED devices is limited, and it is difficult to control the doping ratio accurately, especially the low concentration doping. The solution spin-coating rule can effectively improve the shortcomings in this aspect. By combining the spin coating process and the evaporation process, the advantages of the two kinds of thin film preparation processes can be concentrated and the performance of the device can be optimized. In order to improve the performance of a single material, an effective hybrid charge injection layer was prepared by organic-inorganic hybrid method. The charge transfer effect caused by doping can improve the injection characteristics of OLED devices. In organic materials, organic acids or organic bases are selected to react with other acids and bases to form organic salts (TS-CuPC). For inorganic salts, some metal oxides, such as Mo O3, are selected because they can be prepared by solution method, so they are a very environmentally friendly and low-cost technology. In addition, UV/vis,XPS analysis shows that there is a charge transfer phenomenon in the near infrared region, which can be used to fabricate near infrared optoelectronic devices. In the aspect of devices, the device based on organic-inorganic hybrid charge injection layer not only has low driving voltage, but also has higher efficiency than that of single material as charge injection device. It is found that the enhancement of hole injection in OLEDs is due to the decrease of the barrier of hole injection at the ITO side, which is consistent with the Schottky heat emission mechanism. The effective work function modification in the ITO side has been further confirmed by UPS analysis. In addition, in order to solve the problem that the quantum efficiency of fluorescence is not more than 25%, we found that pyrimidine ligand is a very good substrate because of its good thermal stability and morphological stability. The Ir red light complexes based on pyrimidine ligands can achieve an external quantum efficiency of more than 28%. On the basis of this, we introduce another auxiliary ligand, 2F- 5-dimethylhexane-3- (4-dione), with pyrimidine ligands as the center, and synthesize the red light materials which can be used for spin coating. The lumen efficiency of the prepared device can reach 27.2 cd A-1. In combination with another classic blue-phosphorescent material, FIrpic, the two-color white light device is 28.9 cd A-1, and a good standard international color rendering index (CIE) (0.450.41) has been obtained. From a physiological point of view, this is a very suitable for human lighting, a warm white light source. Because of its high internal quantum efficiency, simple preparation method and low cost, the novel red phosphor can be widely used in the preparation of high efficiency spin-coating devices.
【学位授予单位】：苏州大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TN312.8

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