Thermally activated delayed fluorescent (TADF) emitters are one of the most promising candidates for developing low‐cost organic light‐emitting devices (OLEDs) that can achieve an internal quantum efficiency of 100%. However, the power efficiency values are still significantly lower than that of their phosphorescent counterparts. To achieve high power efficiency, both a high external quantum efficiency and low drive voltage are required. Here, TADF OLEDs with an ultrahigh power efficiency of 133 lm W⁻¹ and an unprecedented low turn‐on voltage of 2.22 V are successfully developed via the strategic use of electron‐transport materials (ETMs). 9‐[4‐(4,6‐Diphenyl‐1,3,5‐triazin‐2‐yl)phenyl]‐N,N,N′,N′‐tetraphenyl‐9H‐carbazole‐3,6‐diamine as a TADF emitter is used. A series of green TADF OLEDs are fabricated using two different types of pyrimidine‐based ETMs as an exciplex host partner and electron‐transport layer to minimize the drive voltages. The optimized device shows an external quantum efficiency of 29.2% and maximum power efficiency of 133.2 lm W⁻¹ without any light‐outcoupling enhancement. The device also shows 124.0 lm W⁻¹ at 100 cd m⁻² and 95.2 lm W⁻¹ at a high brightness of 1000 cd m⁻². The drive voltages are 2.48 V at 100 cd m⁻² and 2.88 V at 1000 cd m⁻².

中文翻译：

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通过电子传输材料的战略使用来实现超高功率效率的热活化延迟荧光OLED

热激活延迟荧光（TADF）发射器是开发可实现100％内部量子效率的低成本有机发光器件（OLED）的最有希望的候选者之一。但是，功率效率值仍大大低于其磷光对应物的功率效率值。为了实现高功率效率，既需要高外部量子效率又需要低驱动电压。在这里，通过战略性地使用电子传输材料（ETM）成功开发了具有133 lm W ^-1的超高功率效率和2.22 V的空前低导通电压的TADF OLED 。9- [4-（4,6-二苯基-1,3,5-三嗪-2-基）苯基] -N，N，N'，N使用′-四苯基-9H-咔唑-3,6-二胺作为TADF发射剂。使用两种不同类型的基于嘧啶的ETM作为激基复合物主配体和电子传输层，制造了一系列绿色TADF OLED，以最大程度地降低驱动电压。经过优化的器件显示出29.2％的外部量子效率和133.2 lm W ^-1的最大功率效率，而没有任何光耦合的增强。该装置还显示124.0流明W¯¯ ^-1以100cd米^-2和95.2流明w ^ ^-1在1000 CD m的高亮度^-2。驱动电压在100 cd m ^-2时为2.48 V，在1000 cd m ^{-2时为2.88V}。