Organic light‐emitting diodes (OLEDs) have become a mainstream display technology in consumer electronics. Self‐emitting ability, transparency, true dark tone, and capability of being made flexible are some of the features of OLED displays, leading to a superior performance compared with liquid crystal displays. In addition to displays, OLEDs are also a strong candidate for lighting applications. Despite great advances in improving the internal quantum efficiency of an OLED to nearly 100%, the external quantum efficiency is still lacking behind due to optical losses. This review reports the latest advances in the optical design of OLEDs that address the external coupling efficiency of OLEDs. Discussed at first are the fundamentals of OLED optics and how the refractive indices of different layers in an OLED stack affect the extraction efficiency. Then, this paper reviews how microlens arrays, scattering layers, and corrugated structures can be used to recover the optical losses and improve the external efficiency, and the general optical designs for different optical structures for light extraction are presented.

中文翻译：

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OLED光学设计的最新进展

有机发光二极管（OLED）已成为消费电子领域的主流显示技术。自发光能力，透明性，真正的暗色调和变得灵活的能力是OLED显示器的一些功能，因此与液晶显示器相比具有卓越的性能。除显示器外，OLED也是照明应用的强力候选者。尽管在将OLED的内部量子效率提高到接近100％方面取得了很大的进步，但是由于光学损耗，外部量子效率仍然不足。这篇评论报告了OLED光学设计的最新进展，这些进展解决了OLED的外部耦合效率。首先讨论的是OLED光学的基本原理，以及OLED堆栈中不同层的折射率如何影响提取效率。