Resonance interaction between a molecular transition and a confined electromagnetic field can lead to weak or strong light-matter coupling. Considering the substantial exciton–phonon coupling in thermally activated delayed fluorescence (TADF) materials, it is thus interesting to explore whether weak light-matter coupling can be used to redistribute optical density of states and to change the rate of radiative decay. Here, we demonstrate that the emission distribution of TADF emitters can be reshaped and narrowed in a top-emitting organic light-emitting device (OLED) with a weakly coupled microcavity. The Purcell effect of weak microcavity is found to be different for TADF emitters with different molecular orientations. We demonstrate that radiative rates of the TADF emitters with vertical orientation can be substantial increased in weakly coupled organic microcavity. These observations can enhance external quantum efficiencies, reduce efficiency roll-off, and improve color-purities of TADF OLEDs, especially for emitters without highly horizontal orientation.

分子跃迁与受限电磁场之间的共振相互作用会导致光与物质的弱或强耦合。考虑到热激活延迟荧光 (TADF) 材料中大量的激子 - 声子耦合，因此探索弱光 - 物质耦合是否可用于重新分配状态的光密度和改变辐射衰减率是很有趣的。在这里，我们证明了 TADF 发射器的发射分布可以在具有弱耦合微腔的顶部发射有机发光器件 (OLED) 中重塑和缩小。发现弱微腔的珀塞尔效应对于具有不同分子取向的 TADF 发射器是不同的。我们证明，在弱耦合有机微腔中，垂直方向的 TADF 发射器的辐射率可以显着增加。这些观察结果可以提高外部量子效率，降低效率滚降，并改善 TADF OLED 的颜色纯度，特别是对于没有高度水平取向的发射器。