Bi-directional organic light-emitting diodes with nanoparticle-enhanced light outcoupling
Bi-directional organic light-emitting diodes with nanoparticle-enhanced light outcoupling
复制标题
DOI：
10.1002/lpor.201300111
复制
发表时间：
2013-11-01
影响因子：
11
通讯作者：
Gather, Malte C.
中科院分区：
文献类型：
--
作者：
Chang, Hong-Wei;Lee, Jonghee;Gather, Malte C.
提出了一种提高半透明/双向有机电致发光器件（TL/BD-OLED）输出耦合效率的有效方法，该器件具有底部氧化铟锡（ITO）阳极和顶部阴极，该顶部阴极由薄Ag层和有机覆盖层组成。当在衬底和ITO阳极之间插入基于纳米颗粒（NP）的散射层（NPSL）时，TL/BD-OLED在两个发射方向上都表现出显著增强的外量子效率（EQE）。此外，NPSL改善了TL/BD-OLED在宽视角范围内的颜色稳定性。基于几何和统计光学的模拟进行阐明的机制，提高效率，并建立进一步优化的策略。对具有不同NP体积百分比的散射层进行的模拟显示，底侧发射受膜中的NP的波导模式提取和后向散射之间的竞争支配，而顶侧发射在很大程度上由后者主导。与没有NPSL的参考器件相比，优化的双向OLED实现了1.64倍增强的EQE。
An effective method is presented for enhancing the outcoupling efficiency of translucent/bi-directional organic light-emitting diodes (TL/BD-OLEDs) with a bottom indium tin oxide (ITO) anode and a top cathode comprised of a thin Ag layer covered with an organic capping layer. Upon insertion of a nanoparticle (NP)-based scattering layer (NPSL) between the substrate and the ITO anode, the TL/BD-OLEDs exhibit significantly enhanced external quantum efficiency (EQE) in both emission directions. Furthermore, the NPSL improves the color stability of the TL/BD-OLEDs over a wide range of viewing angles. Simulations based on geometrical and statistical optics are performed to elucidate the mechanism by which the efficiency is enhanced and to establish strategies for further optimization. Simulations performed on the scattering layers with varying NP volume percentage reveal that the bottom-side emission is governed by competition between waveguide-mode extraction and backward scattering by NPs in the film, while the top-side emission is largely dominated by the latter. Optimized bi-directional OLEDs achieve a 1.64-fold enhanced EQE compared to reference devices without NPSL.