Light‐emitting field‐effect transistors (LEFETs) are an emerging type of devices that combine light‐emitting properties with logical switching function. One of the factors limiting their efficiency stems from the spin statistics of electrically generated excitons. Only 25% of them, short lived singlet states, are capable of light emission, with the other 75% being long lived triplet states that are wasted as heat due to spin‐forbidden processes. Traditionally, the way to overcome this limitation is to use phosphorescent materials as additional emission channel harnessing the triplet excitons. Here, an alternative strategy for triplet usage in LEFETs in the form of thermally activated delayed fluorescence (TADF) is presented. Devices employing a TADF capable material, 4CzIPN (2,4,5,6‐tetra[9H‐carbazol‐9‐yl]isophthalonitrile), in both n‐type and p‐type configurations are shown. They manifest excellent electrical characteristics, consistent brightness in the range of 100–1,000 cd m^‐2 and external quantum efficiency (EQE) of up to 0.1%, which is comparable to the equivalent organic light‐emitting diode (OLED) based on the same materials. Simulation identifies the poor light out‐coupling as the main reason for lower than expected EQEs. Transmission measurements show it can be partially alleviated using a more transparent top contact, however more structural optimization is needed to tap the full potential of the device.

中文翻译：

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利用热激活延迟荧光的高性能p型和n型发光场效应晶体管

发光场效应晶体管（LEFET）是一种新兴类型的器件，将发光特性与逻辑开关功能结合在一起。限制其效率的因素之一来自于产生的激子的自旋统计。其中只有25％（短寿命的单重态）能够发光，其他75％是长寿命的三重态，由于自旋禁止过程而浪费为热量。传统上，克服此限制的方法是使用磷光材料作为利用三重态激子的附加发射通道。在这里，提出了一种以热激活延迟荧光（TADF）形式在LEFET中使用三重态的替代策略。使用具有TADF功能的材料，4CzIPN（2,4,5,6-四[9H-咔唑-9-基]间苯二甲腈）的设备，同时显示了n型和p型配置。它们表现出出色的电气特性，在100–1,000 cd m的范围内保持一致的亮度^‐2，外部量子效率（EQE）高达0.1％，可与基于相同材料的等效有机发光二极管（OLED）相提并论。仿真确定不良的光输出耦合是导致EQE低于预期的主要原因。传输测量结果表明，使用更透明的顶部触点可以部分缓解这种情况，但是需要更多的结构优化来挖掘设备的全部潜能。