White organic light-emitting diodes (WOLEDs) have widely drawn attention for applications in flat panel display and solid-state lighting. High efficiency and simple device structure are two important factors for large-scale application for WOLEDs. Here, we have presented a relatively reliable method to develop high-performance and doping-free WOLEDs by integrating interfacial exciplex with phosphorescent multi-ultrathin emissive layers. By reasonable design of device architecture, the resulting WOLED with a warm-white light not only realizes a low turn-on voltage of 2.25 V, but also exhibits the high forward-viewing power efficiency and external quantum efficiency of 91.5 lm W⁻¹ and 21.3%, respectively, without light out-coupling enhancement techniques. More importantly, the power efficiency still remain as high as 49.5 lm W⁻¹ at the high luminance of 1000 cd m⁻², which should be one of the best values in reported doping-free WOLEDs. It suggests that multi-ultrathin emissive layers combining with interfacial exciplex can realize the efficient utilization of excitons and improvement of efficiency roll-off.

白色有机发光二极管（WOLED）在平板显示器和固态照明中的应用引起了广泛的关注。高效和简单的器件结构是WOLED大规模应用的两个重要因素。在这里，我们提出了一种相对可靠的方法，该方法通过将界面激基复合物与磷光多超薄层发光层集成来开发高性能且无掺杂的WOLED。通过合理的器件架构设计，得到的带有暖白光的WOLED不仅实现了2.25 V的低导通电压，而且还具有很高的前视功率效率和91.5 lm W ^-1的外部量子效率。和没有光输出耦合增强技术的分别为21.3％。更重要的是，在1000 cd m ^-2的高亮度下，功率效率仍然保持高达49.5 lm W ^-1，这应该是报告的无掺杂WOLED的最佳值之一。提示多超薄层发光层结合界面激基复合物可以实现激子的有效利用和效率降落的改善。