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Applied Physics 2023
通过调控载流子复合和激子能量传递实现非掺杂WOLED的低效率滚降
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Abstract:
基于磷光的白色有机发光二极管(WOLED)具有高效率和环境友好等优点，但仍然面临着制作过程复杂、高亮度下效率衰减的严峻挑战。在本文中，基于多个蓝色界面激基复合物并在其插入薄磷光层，制备了具有低效率滚降和无掺杂层的高效磷光体WOLED。我们提出的器件采用策略性激子管理，通过界面激基复合物对三重态能量进行限制。抑制了高亮度下激子浓度增加所引起的三重态–三重态湮灭(TTA)。同时采用PO-T2T/TPBi异质结有效地减少载流子捕获，有效地降低了载流子俘获所引起的三重态–极化子湮灭(TPA)。所得到的无掺杂的磷光WOLED的最大电流效率(CE)和功率效率(PE)为47.9 cd/A和50.1 lm/W，且3000 cd/m2亮度下的电流效率仍为40.0 cd/A，在无掺杂WOLED中达到了极低的效率滚降。我们的方法为克服无掺杂磷光体WOLED中三重态激子浓度猝灭和载流子俘获所引起的效率衰减提供了一条有效的途径。
White organic light-emitting diode (WOLED) based on phosphor has the advantages of high efficiency and environmental friendliness, but it still faces severe challenges such as complex production process and efficiency roll-off at high luminance. In this paper, a high efficiency phos-phor WOLED with efficiency low roll-off and non-doped layer was fabricated based on multiple blue interfacial exciplexes and inserting thin phosphor layers into them. The proposed device adopts strategic exciton management, and the triplet energy is limited by the interfacial exciplex. The triplet-triplet annihilation (TTA) caused by the increase of exciton concentration at high luminance is suppressed at the same time, PO-T2T/TPBi heterojunction is used to effectively reduce charge carrier capture and effectively reduces triplet-polaron annihilation (TPA) caused by carrier trapping. The maximum current efficiency (CE) and power efficiency (PE) of the obtained non-doped phosphor WOLED are 47.9 cd/A and 50.1 lm/W, and the current efficiency at 3000 cd/m2 luminance is still 40.0 cd/A, which achieves extremely low efficiency roll-off in non-doped WOLED. Our method provides an effective way to overcome the efficiency roll-off caused by triplet exciton concentration quenching and charge carrier trapping in non-doped phosphor WOLED.
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