【作者】 张志强；

【导师】 郝玉英；

【作者基本信息】 太原理工大学 ， 物理电子学， 2009， 硕士

【摘要】 有机电致发光器件(OLED)具有低压直流驱动、主动发光、色彩丰富、视角宽、重量轻、能耗低以及响应速度快等诸多优点,被认为是新一代平板显示器的有力竞争者,其在照明光源和光电耦合器领域也具有诱人前景。经过二十多年的研究,有机电致发光技术得到了长足发展,产品化EL显示器件不断出现,然而由于部分关键问题未能得到解决,致使现有器件寿命短、效率低。目前,提升器件效率主要有两方面的工作在做:提高材料效率;改进器件制备工艺,设计新型结构器件。本文从改进器件结构这一研究方向出发,设计了两套实验方案:1.借鉴已有关于LiF等绝缘材料对OLED性能影响的研究,在器件设计中引入MgF2,系统研究了MgF2插层位置、插层厚度变化对器件性能的影响。首先利用MgF2修饰阴极,制作了器件结构为ITO / NPB / Alq3 / MgF2 / Al,MgF2厚度分别为0.5nm、0.8nm、1.0nm的一组EL器件,研究发现:MgF2厚度的改变对器件性能有很大影响,MgF2厚度为0.8nm的器件与其他两个器件相比,性能最优,器件启亮电压降低到2.1V,最大亮度达到1682cd/m2,电流效率和流明效率分别为1.14cd/A、1.48lm/W;其次我们将MgF2穿插在空穴传输层NPB中,制作了器件结构为ITO / NPB(10nm)/ MgF2(0nm、0.5nm、1.0nm、1.5nm)/ NPB(20nm)/ Alq3(30nm)/ Al(30nm)的一组器件,测试结果表明:合适厚度的MgF2可有效降低器件启亮电压,提高器件效率。本实验中MgF2厚度0.5nm的器件启亮电压只有2.3V,较未穿插MgF2器件降低2V;MgF2厚度1.0nm的器件最大电流效率达到0.86cd/A,最大流明效率达到0.52 lm/W,较未穿插MgF2器件分别提高43%和174%。2.从降低启亮电压、稳定器件性能的目的出发,设计了一种界面交互穿插结构器件。新器件将功能层间平直形界面设计为矩形凹凸穿插状,提高了电子注入、传输效率,实现了器件性能提升。实验系统研究了界面交互穿插数目、厚度对器件性能的影响,得出结论:随着交互穿插数目的增加,器件启亮电压降低、发光效率提高,同时,穿插厚度的变化对器件性能有很大影响。所制备器件中,交互穿插厚度7nm、穿插数目3的器件性能最优,启亮电压较普通结构器件降低1V,最大电流效率提高34%,且稳定性显著提高。更多还原

【Abstract】 Organic light-emitting device (OLED) is a very attractive candidate as the next generation flat panel displays (FPD).The technology exhibits bright prospect in photoelectricity filed owing to its advantages of low DC drive voltage, active luminescence, full color, low power consumption and fast response. After more than twenty years of studies, Organic light-emitting diode technology has been developed by leaps and bounds, the product of EL display devices emerge continually. However, some of the key issues can not be resolved, so that OLEDs still have a short life and low efficiency. At present, enhancing the efficiency of device has two main aspects of work to do: improve the material efficiency; improve preparation process and design new structure of the device.Two sets of programs to optimize device performance were designed in this paper:1. Based on the research of LiF, MgF2 was inserted in the device. The influence of the location and thickness of the MgF2 layer on device performance was studied, respectively. First, MgF2 was used to modify cathode. The devices of ITO / NPB / Alq3 / MgF2 / Al, herein MgF2 layer thickness is 0.5nm, 0.8nm and 1.0nm, respectively, were made. The study indicate that the change of the thickness of the MgF2 layer has a great impact on device performance. The device with the MgF2 layer thickness of 0.8nm, with the turn on voltage of 2.1V, the maximum brightness of 1682cd/m2, luminous efficiency of 1.14cd/A and power efficiency of 1.48lm/W, is superior to the other two devices. Secondly, we inserted MgF2 into the holes transport layer (NPB). The device structure is ITO/ NPB(10nm)/MgF2(0nm,0.5nm,1.0nm,1.5nm)/NPB(20nm)/Alq3(30nm)/Al(30nm). Tests show that introducing the MgF2 layer of suitable thickness can decrease the turn on voltage and increase the efficiency of the device. In this experiment, the turn on voltage of the device with 0.5nm-thick MgF2 layer is 2.3V, which is 2V lower than that without MgF2 layer. The maximum luminous efficiency and power efficiency of the device with 1.0nm-thick MgF2 layer are 0.86cd/A and 0.52 lm/W, respectively, which are increased by 43% and 174% compared with that without MgF2 layer, respectively.2. Aiming to lower turn on voltage and stabilize the performance,a new structure device was designed. We change the straight-shaped interface of the device into rectangular interinserting interface. By doing this, the efficiency of electron injection and transport was improved, and the device performance was promoted. We studied the impact of the number and the thickness of rectangular interinserting structure on device performance. The results indicate that the device with lower turn on voltage and high efficiency, with the increasing of the number of rectangular interinserting structure. Meanwhile, the thickness of interinserting structure has an important influence on the device performance. The interinserting device with the thickness of 7nm and the number of 3 has a much better performance than other devices, whose turn on voltage is 1V lower than the traditional device and the maximum luminous efficiency is improved by 34%. Furthermore, the stability of the devices improved significantly.更多还原