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A π-D and π-A Exciplex-Forming Host for High-Efficiency and Long-Lifetime Single-Emissive-Layer Fluorescent White Organic Light-Emitting Diodes.
Advanced Materials ( IF 29.4 ) Pub Date : 2020-09-06 , DOI: 10.1002/adma.202004040
Chen Zhang 1 , Yang Lu 1 , Ziyang Liu 1 , Yuewei Zhang 1 , Xuewen Wang 2 , Dongdong Zhang 1 , Lian Duan 1, 3
Affiliation  

Exciplex‐forming hosts with thermally activated delayed fluorescence (TADF) provide a viable opportunity to unlock the full potential of the yet‐to‐be improved power efficiencies (PEs) and stabilities of all‐fluorescent white organic light‐emitting diodes (WOLEDs), but this, however, is hindered by the lack of stable blue exciplexes. Here, an advanced exciplex system is proposed by incorporating bipolar charge‐transport π‐spacers into both the electron‐donor (D) and the electron‐accepter (A) to increase their distance for hypsochromic‐shifted emission while maintaining the superior transporting ability. By using spirofluorene as the π‐spacer, 3,3′‐bicarbazole as the D‐unit, and 2,4,6‐triphenyl‐1,3,5‐triazine as the A‐unit, a π–D and π–A exciplex with sky‐blue emission and fast reverse intersystem crossing process is thereof constructed. Combining this exciplex‐forming host, a blue TADF‐sensitizer, and a yellow conventional fluorescent dopant in a single‐emissive‐layer, the fabricated warm‐white‐emissive device simultaneously exhibits a low driving voltage of 3.08 V, an external quantum efficiency of 21.4%, and a remarkable T80 (time to 80% of the initial luminance) of >8200 h at 1000 cd m−2, accompanied by a new benchmark PE of 69.6 lm W−1 among all‐fluorescent WOLEDs.

中文翻译:

高效率和长寿命单发射层荧光白色有机发光二极管的π-D和π-A激基形成主体。

具有热激活延迟荧光(TADF)的形成激基复合物的宿主提供了一个可行的机会,以释放尚未完全改善的功率效率(PE)和全荧光白色有机发光二极管(WOLED)的稳定性的全部潜力,但是,这由于缺乏稳定的蓝色激基复合物而受到阻碍。在此,提出了一种先进的激基复合物系统,该方法通过将双极电荷传输π间隔物同时结合到电子给体(D)和电子受体(A)中,以增加它们的变色发射距离,同时保持出色的传输能力。通过使用螺芴作为π间隔物,使用3,3'-联咔唑作为D-单元,并使用2,4,6-三苯基-1,3,5-三嗪作为A单元,则π–D和π–构造了具有天蓝色发射和快速逆系统间穿越过程的激基复合物。−2,同时在全荧光WOLED中新基准PE为69.6 lm W -1
更新日期:2020-10-20
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