The balance between the electrical performance and quenching suppression is crucial to develop the efficient host materials for full-thermally activated delayed fluorescence (TADF) white organic light-emitting diodes (WOLEDs). In this work, through introducing one bulky diphenylphosphine oxide (DPPO) group at 4 position of each xanthene ring in a symmetrical and orthogonal spirobi[xanthene] (SX) skeleton, 9,9′-spirobi[xanthene]-4,4′-diylbis(diphenylphosphine oxide) (SXDPO) was constructed, giving rise to the optimized intermolecular interactions. Besides the high triplet (T₁) energy level of 2.94 eV, the highly rigid configuration of SXDPO simultaneously rendered the dramatically suppressed excited-state relaxation and the stable and uniform amorphous phase of its films before and after doping TADF dyes. It was interesting that SXDPO showed the complementary electrical properties to enhance the carrier transportation in the films. Therefore, SXDPO successfully achieved the balance between the electrical performance improvement and the collisional quenching suppression. As the result, SXDPO endowed its complementary TADF WOLEDs with the state-of-the-art performance, e.g. the turn-on voltage as low as 2.8 V and power efficiency beyond 60 lm W⁻¹, which was one of the best comprehensive results reported so far for full-TADF WOLEDs.

电气性能和猝灭抑制之间的平衡对于开发用于全热活化延迟荧光（TADF）白色有机发光二极管（WOLED）的高效主体材料至关重要。在这项工作中，通过在对称且正交的螺双并[xanthene]（SX）骨架的每个x吨环的4个位置引入一个庞大的二苯基氧化膦（DPPO）基团，可以实现9,9'-spirobi [xanthene] -4,4'-构造了二基双（二苯基氧化膦）（SXDPO），从而产生了优化的分子间相互作用。除了2.94 eV的高三重态（T ₁）能级之外，SXDPO的高刚性配置同时在掺杂TADF染料之前和之后，都显着抑制了激发态弛豫，并使其薄膜具有稳定且均匀的非晶相。有趣的是，SXDPO显示出互补的电性能，以增强薄膜中载流子的传输。因此，SXDPO成功地实现了电性能提高与碰撞猝灭抑制之间的平衡。结果，SXDPO赋予了其互补的TADF WOLED先进的性能，例如低至2.8 V的开启电压和超过60 lm W ^-1的功率效率，这是最佳的综合结果之一到目前为止，已经报道了全TADF WOLED。