Department of Physics, University of Michigan, 2238 EECS, Ann Arbor, Michigan 48109, USA.
Department of Electrical Engineering and Computer Science, University of Michigan, 2238 EECS, Ann Arbor, Michigan 48109, USA.
Nat Commun. 2014 Sep 25;5:5008. doi: 10.1038/ncomms6008.
Organic light-emitting diodes are a major driving force of the current information display revolution due to their low power consumption and potentially long operational lifetime. Although electrophosphorescent organic emitters have significantly lower power consumption than fluorescent emitters, the short lifetime of electrophosphorescent blue devices has prevented their application in displays for more than a decade. Here, we demonstrate a novel blue electrophosphorescent device with a graded dopant concentration profile in a broadened emissive layer, leading to a lower exciton density compared with a conventional device. Thus, triplet-polaron annihilation that leads to long-term luminescent degradation is suppressed, resulting in a more than threefold lifetime improvement. When this strategy is applied to a two-unit stacked device, we demonstrate a lifetime of 616±10 h (time to 80% of the 1,000 cd m(-2) initial luminance) with chromaticity coordinates of [0.15, 0.29], representing a tenfold lifetime improvement over a conventional blue electrophosphorescent device.
有机发光二极管由于其低功耗和潜在的长工作寿命，是当前信息显示革命的主要推动力。尽管电致磷光有机发射器的功耗明显低于荧光发射器，但电致磷光蓝色器件的短寿命使其在显示器中的应用超过了十年。在这里，我们展示了一种新型的蓝色电致磷光器件，其在扩展的发射层中具有梯度掺杂浓度分布，与传统器件相比，激子密度更低。因此，导致长期发光降解的三重态极化子复合被抑制，从而使寿命提高了三倍以上。当这种策略应用于两个单元堆叠器件时，我们演示了寿命为 616±10 h（时间到初始亮度的 1000 cd m(-2) 的 80%），色度坐标为[0.15, 0.29]，与传统的蓝色电致磷光器件相比，寿命提高了十倍。
