High-performance solution-processed red hyperfluorescent OLEDs based on cibalackrot
High-performance solution-processed red hyperfluorescent OLEDs based on cibalackrot
复制标题
基于 cibalackrot 的高性能溶液加工红色超荧光 OLED
DOI：
10.1039/d1tc04937b
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发表时间：
2022
影响因子：
6.4
通讯作者：
Lo Shih-Chun
中科院分区：
文献类型：
--
作者：
Wallwork Nicholle R.;Mamada Masashi;Shukla Atul;McGregor Sarah K. M.;Adachi Chihaya;Namdas Ebinazar B.;Lo Shih-Chun
超荧光有机发光二极管 (OLED) 使用荧光发射器实现了卓越的器件性能。使用热蒸发发射层实现了卓越的器件性能。然而，对于未来的大规模商业化，必须使用低成本溶液处理技术获得类似的器件性能。就超荧光 OLED 而言，三种活性成分之间的分子相互作用和间距仍然存在微妙的相互作用：主体、热激活延迟荧光 (TADF) 辅助主体和荧光发射体。材料的分散是影响器件效率的主要因素，使得高效的溶液处理器件更加难以实现。在此，我们在 CBP 中使用 cibalackrot 作为荧光发射体和 4CzIPN-tBu 作为 TADF 辅助主体，展示了溶液处理的超荧光器件，外量子效率 (EQE) 为 15.3%。通过研究在三元和无主体二元共混物中使用 4CzIPN 或 4CzIPN-tBu 作为 TADF 辅助主体，我们发现在 TADF 材料中添加叔丁基对器件性能做出了重大贡献。这些位阻基团通过在空间上分离相邻分子并降低同时前沿分子轨道（FMO）的可能性，有效减少了 TADF 辅助主体和荧光发射体之间三线态扩散引起的损失。
Hyperfluorescent organic light-emitting diodes (OLEDs) have allowed remarkable device performances to be achieved using fluorescent emitters. Superior device performance has been realised using thermally evaporated emissive layers. However, for future large-scale commercialisation, it is essential to obtain similar device performances using low-cost solution-processing techniques. In the case of hyperfluorescent OLEDs, there remains a delicate interplay of molecular interactions and spacing between the three active components: a host, a thermally activated delayed fluorescent (TADF) assistant host, and a fluorescent emitter. Dispersion of the materials is a dominating factor towards the device efficiencies, making efficient solution-processed devices all the more difficult to achieve. Herein, we have demonstrated solution-processed hyperfluorescent devices with an external quantum efficiency (EQE) of 15.3% using cibalackrot as the fluorescent emitter and 4CzIPN-tBu as the TADF assistant host in CBP. By studying the use of either 4CzIPN or 4CzIPN-tBu as the TADF assistant host in both ternary and host-free binary blends, we found that the addition of tert-butyl groups to the TADF material made a significant contribution to the device performance. These sterically hindered groups effectively reduced losses caused by triplet diffusion between the TADF assistant host and the fluorescent emitter by spatially separating adjacent molecules and making a concurrent frontier molecular orbital (FMO) less likely.