螺吖啶上的供体延伸可实现高效 TADF-OLED，并缓解效率下降,Advanced Functional Materials

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螺吖啶上的供体延伸可实现高效 TADF-OLED，并缓解效率下降
Advanced Functional Materials ( IF 18.5 ) Pub Date : 2023-01-17 , DOI: 10.1002/adfm.202211696
Hao Peng ₁ , Yulin Xu ₁ , Changjiang Zhou ₂ , Ranran Pei ₁ , Jingsheng Miao ₁ , He Liu ₁ , Chuluo Yang ₁

Affiliation

基于热激活延迟荧光 (TADF) 发射器的有机发光二极管具有高外部量子效率 (EQE) 和低效率滚降的迫切需要。开发了三种基于芴-螺-吖啶衍生物作为供体的 TADF 发射体。由刚性供体和受体组成，所有发射体都表现出 96-99% 的高 PLQY。吖啶上的直接共轭在 IA-TRZ 中提供了增强的反向系统间交叉 ( k _RISC )，而通过螺结的延伸加速了辐射衰减率 ( k _r) 在 2S-TRZ 和 IT-TRZ 中。值得注意的是，所有发射体都具有高电致发光性能，2S-TRZ 的 EQE 分别为 35.6%、IT-TRZ 的 36.1% 和 IA-TRZ 的 32.0%，以及高达 100 000 cd m -2 的非常高的^亮度。令人惊讶的是，与 IA-TRZ 相比，拥有更大k _r和更小k _RISC的 2S-TRZ 和 IT-TRZ 表现出更轻松的效率滚降，表明k _r的重要性。更重要的是，具有中等k _r和k _{RISC的 IT-TRZ}在这些发射器中，滚降最低，这表明全面考虑所有光物理过程对于获得出色的器件非常重要。它还强调了通过侧基的分子调制方法，可以对衰变通道进行精细控制，以精细优化发射体。这项研究可以为设计实际发射器提供有用的视角。

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Donor Extension on Spiro-Acridine Enables Highly Efficient TADF-OLEDs with Relieved Efficiency Roll-Off

Organic light emitting diodes based on thermally activated delayed fluorescent (TADF) emitters with both high external quantum efficiency (EQE) and low efficiency roll-off are under urgent pursuing. Three TADF emitters based on fluorene-spiro-acridine derivatives as donors are developed. Composing of rigid donor and acceptor, all emitters exhibit high PLQYs of 96–99%. Direct conjugation attached on acridine offers an enhanced reverse intersystem crossing (k_RISC) in IA-TRZ, while the extension via spiro-junction accelerates the radiative decay rate (k_r) in 2S-TRZ and IT-TRZ. Remarkably, all emitters enable high electroluminescent performance with EQE of 35.6% for 2S-TRZ, 36.1% for IT-TRZ and 32.0% for IA-TRZ, respectively, and very high luminance of up to 100 000 cd m⁻². Surprisingly, 2S-TRZ and IT-TRZ that hold larger k_r and smaller k_RISC than that of IA-TRZ exhibit more relieved efficiency roll-off, indicating the significance of k_r. More importantly, IT-TRZ with a moderate k_r and k_RISC among these emitters shows the lowest roll-off which demonstrates that the comprehensive consideration of all photophysical processes is important to attain excellent devices. It also emphasizes the molecular modulation method through side group that can induce elaborate control on decay channels for finely optimizing emitters. This study can provide a useful perspective in designing practical emitters.

更新日期：2023-01-17

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