Thermally activated delayed fluorescence (TADF) emitters can harvest singlet and triplet excitons for light emission to afford highly efficient organic light-emitting diode (OLED) devices, especially for all-TADF white OLEDs (WOLEDs). However, the majority of TADF emitters suffer from concentration quenching effects and require complicated doping techniques for device fabrication. Herein, we demonstrate a yellow TADF emitter that enables non-doped OLED systems, which is beneficial for the simplification of the OLED device structure and fabrication. The non-doped yellow OLED achieves a maximum external quantum efficiency (EQE) of 16.7% at a high luminance of 3600 cd m⁻², in which such a high magnitude is rarely reported. More significantly, by the combination of the yellow TADF emitter with a blue TADF emitter, a fully non-doped emissive layer (EML) strategy has been demonstrated for the fabrication of an all-TADF WOLED, in which the non-doped yellow and blue TADF emissive layers are closely stacked together without any interlayers. The fully non-doped WOLEDs show a maximum EQE of up to 19.8%, along with high quality white-light emission. This is the first report regarding the fully non-doped all-TADF WOLEDs, and the presented design strategy provides a universal route towards the fabrication of simple and efficient WOLEDs.

中文翻译：

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完全由热激活的延迟荧光发射器组成的高效，完全无掺杂的白色有机发光二极管†

热激活延迟荧光（TADF）发射器可以收集单线态和三线态激子用于发光，从而提供高效的有机发光二极管（OLED）器件，尤其是用于全TADF白色OLED（WOLED）的器件。但是，大多数TADF发射极都具有浓度猝灭效应，并且需要复杂的掺杂技术来制造器件。本文中，我们演示了一种黄色TADF发射器，该发射器可以实现非掺杂的OLED系统，这对于简化OLED器件的结构和制造非常有帮助。未掺杂的黄色OLED在3600 cd m ^-2的高亮度下实现了16.7％的最大外部量子效率（EQE），其中很少有如此高的报道。更重要的是，通过将黄色TADF发射器与蓝色TADF发射器相结合，已经证明了用于制造全TADF WOLED的完全非掺杂的发射层（EML）策略，其中非掺杂的黄色和蓝色TADF发光层紧密堆叠在一起，没有任何夹层。完全未掺杂的WOLED的最大EQE高达19.8％，并且具有高品质的白光发射。这是有关完全非掺杂的全TADF WOLED的第一份报告，提出的设计策略为制造简单高效的WOLED提供了一条通用途径。