We report a highly efficient blue thermally activated delayed fluorescence (TADF) emitter, namely, MCz-TXO. MCz-TXO exhibits close energy level matching of the three states: charge transfer (CT) and locally excited triplet states, and a CT singlet state. Owing to the good energy level matching and heavy atom effect of sulfur in the molecular structure, MCz-TXO shows very large experimental rate constant of reverse intersystem crossing (k _RISC) of ∼2נ10⁸s⁻¹. This is one of the largest k _RISC values among all reported pure organic TADF emitters. The MCz-TXO based organic light-emitting diodes exhibit blue emission with maximum external quantum efficiency of 17.4%.

我们报告了一种高效的蓝色热激活延迟荧光 (TADF) 发射器，即 MCz-TXO。MCz-TXO 表现出三种状态的紧密能级匹配：电荷转移 (CT) 和局部激发三重态，以及 CT 单重态。由于分子结构中硫的良好能级匹配和重原子效应，MCz-TXO 显示出非常大的反向系统间交叉实验速率常数 ( k _RISC ) ～2נ10 ⁸ s ^-1。这是所有报道的纯有机 TADF 发射体中最大的k _RISC值之一。基于 MCz-TXO 的有机发光二极管表现出蓝色发射，最大外量子效率为 17.4%。