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Dipole-Dipole Interaction Management for Efficient Blue Thermally Activated Delayed Fluorescence Diodes
Chem ( IF 23.5 ) Pub Date : 2018-07-05 , DOI: 10.1016/j.chempr.2018.06.005
Chunmiao Han , Zhen Zhang , Dongxue Ding , Hui Xu

Thermally activated delayed fluorescence (TADF) diodes have emerged in recent years. However, blue devices still suffer from low luminance and serious efficiency roll-off, partially because of the utilization of unipolar host materials, which can suppress interaction-induced quenching at the cost of carrier flux unbalance. Herein, we demonstrate that the strong host excited-state dipole field can significantly worsen exciton quenching of blue TADF dopants through host-dopant dipole-dipole interactions. To integrate low excited-state polarity and ambipolar characteristics, we developed a donor-σ-acceptor host with dramatically reduced excited-state dipole moments by one order of magnitude to only ∼2 Debye, which gave rise to state-of-the-art external quantum efficiency beyond 20% from its devices, as well as record-low roll-off. Comparison between the device efficiencies of the hosts and various excited-state polarities revealed that the suppression of dipole-dipole interaction-induced quenching is the primary determinant of device performance for ambipolar blue TADF hosts.



中文翻译:

高效蓝色热激活延迟荧光二极管的偶极-偶极相互作用管理

近年来出现了热激活延迟荧光(TADF)二极管。然而,蓝色器件仍然遭受低亮度和严重的效率下降的影响,部分原因是由于利用了单极基质材料,该材料可以抑制相互作用引起的猝灭,但以载流子不平衡为代价。在这里,我们证明了强的宿主激发态偶极子场可以通过宿主-掺杂子偶极-偶极子相互作用显着恶化蓝色TADF掺杂物的激子猝灭。为了整合低激发态极性和双极性特性,我们开发了一种供体-σ受体主体,其激发态偶极矩显着降低了一个数量级,仅为〜2 Debye,从而产生了最新技术。器件的外部量子效率超过20%,并且滚降极低。

更新日期:2018-07-05
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