Organic light-emitting diodes (OLEDs) employing purely organic functional materials indicate a low-cost manufacturing route towards the next-generation display and solid-state lighting owing to the avoidance of noble heavy metal complex phosphorescent emitters. In recent years, several mechanisms have been proposed to design high performance purely organic emitters. This new generation of purely organic emitters shed light on the realization of both low-cost and high performances. The main idea of this paper is to review how to use purely organic semiconductors to realize high-efficiency OLEDs. This guides us to pay special attention to two aspects: 1) how to break the efficiency bottleneck resulting from exciton spin-statistics, which is critical to determine internal quantum efficiency; 2) how to enhance out-coupling efficiency by molecular designs, which eventually influences on external quantum efficiency. Several significant material design strategies are thus introduced, and the relevant mechanisms are classified as triplet-triplet annihilation, thermally activated delayed fluorescence, hot excitons, room temperature phosphorescence, and luminescent radicals. Then, device strategies by employing organic heterojunctions as the main luminescent center towards high-performance fluorescent OLEDs were introduced. Finally, we outline the progress of enhancing out-coupling efficiency by tuning the dipole orientation of emitters and the operational stability of OLEDs excluding noble heavy metal complex phosphorescent emitters.

由于避免了贵重金属络合物磷光发光体，采用纯有机功能材料的有机发光二极管（OLED）指示了走向下一代显示器和固态照明的低成本制造途径。近年来，已经提出了几种机制来设计高性能的纯有机发射体。新一代的纯有机发射器为实现低成本和高性能提供了亮点。本文的主要思想是回顾如何使用纯有机半导体来实现高效OLED。这引导我们特别注意两个方面：1）如何克服由于激子自旋统计而产生的效率瓶颈，这对于确定内部量子效率至关重要。2）如何通过分子设计提高外耦合效率，最终影响外部量子效率。因此，引入了几种重要的材料设计策略，并且相关的机理分类为三重态-三重态an灭，热激活的延迟荧光，热激子，室温磷光和发光自由基。然后，介绍了通过采用有机异质结作为高性能荧光OLED的主要发光中心的器件策略。最后，我们概述了通过调整发射极的偶极子方向和提高OLED的工作稳定性（不包括贵重金属复合磷光发射极）来提高耦合输出效率的进展。因此，引入了几种重要的材料设计策略，并且相关的机理分类为三重态-三重态an灭，热激活的延迟荧光，热激子，室温磷光和发光自由基。然后，介绍了通过采用有机异质结作为高性能荧光OLED的主要发光中心的器件策略。最后，我们概述了通过调整发射极的偶极子方向和提高OLED的工作稳定性（不包括贵重金属复合磷光发射极）来提高耦合输出效率的进展。因此，引入了几种重要的材料设计策略，并且相关的机理分类为三重态-三重态an灭，热激活的延迟荧光，热激子，室温磷光和发光自由基。然后，介绍了通过采用有机异质结作为高性能荧光OLED的主要发光中心的器件策略。最后，我们概述了通过调整发射极的偶极子方向和提高OLED的工作稳定性（不包括贵重金属复合磷光发射极）来提高耦合输出效率的进展。介绍了通过采用有机异质结作为高性能荧光OLED的主要发光中心的器件策略。最后，我们概述了通过调整发射极的偶极子方向和提高OLED的工作稳定性（不包括贵重金属复合磷光发射极）来提高耦合输出效率的进展。介绍了通过采用有机异质结作为高性能荧光OLED的主要发光中心的器件策略。最后，我们概述了通过调整发射极的偶极子方向和提高OLED的工作稳定性（不包括贵重金属复合磷光发射极）来提高耦合输出效率的进展。