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1、太原理工大学硕士研究生学位论文 I有机电致发光器件结构优化设计研究 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
2、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
3、， 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；太原理工大学硕士研究生学位论文 IIMgF2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
4、，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。 关键词： 有机电致发光器件，结构优化，氟化镁，界面交互穿插 太原理工大学硕士研究生学位论文 IIISTUDY ON STRUCTURE OPTIMIZATION O
5、F ORGANIC LIGHT-EMITTING DEVICES 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
6、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
7、 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
8、. 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
9、.8nm and 1.0nm, respectively, were made. The study indicate that the change of the 太原理工大学硕士研究生学位论文 IVthickness 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, luminou
10、s 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 lay
11、er 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
12、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 in
13、terface 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 performanc
14、e. 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 太原理工大学硕士研究生
15、学位论文 Vdevice 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. KEY WOR
16、DS: Organic light-emitting device, structure optimization, MgF2，interinserting interface 太原理工大学硕士研究生学位论文 VIII主要符号说明 缩写代号 英文全称 中文全称 OLED organic light-emitting device 有机电致发光器件 PL photoluminescence 光致发光 EL electroluminescence 电致发光 CIE The Commission International de LEclairage 国际照明委员会 EML emitting layer 发光层 HTL hole transport layer 空穴传输层 ETL electron transport layer 电子传输层 ITO indium-tin-oxide 氧化铟锡 LUMO lowest unoccupied molecular orbits 最低空轨道 HOMO highest occupied molecular orbits 最高占据轨道 NP
