多共振 TADF 发射器的密集局部三重态和空间屏蔽使高性能深蓝色 OLED 成为可能,Advanced Materials

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多共振 TADF 发射器的密集局部三重态和空间屏蔽使高性能深蓝色 OLED 成为可能
Advanced Materials ( IF 27.4 ) Pub Date : 2022-10-12 , DOI: 10.1002/adma.202207416
Hyung-Jin Cheon ₁ , Seung-Je Woo ₂ , Seung-Hyun Baek ₃ , Jeong-Hwan Lee _{3,

4} , Yun-Hi Kim ₁

Affiliation

基于硼和氮原子的多共振热激活延迟荧光 (MR-TADF) 分子因其窄发射光谱和三线态捕获特性而成为有机发光二极管 (OLED) 的下一代蓝色发射体。然而，源自典型 MR-TADF 分子平面结构的分子间聚集会导致浓度猝灭和加宽光谱，从而限制了 MR-TADF 发射体的全部潜力的利用。在此，开发了一种深蓝色 MR-TADF 发射器p BP-DABNA-Me 以有效抑制分子间相互作用。此外，光物理研究和理论计算表明，将联苯部分添加到核心体会在 S _{1附近产生致密的局部三重态}和 T ₁能量，让发射极有效地收集激子。基于p BP-DABNA-Me 的 OLED 显示出 23.4% 的高外部量子效率 (EQE) 和纯蓝色发射，国际照明委员会 (CIE) 坐标为 (0.132, 0.092)，即使在 100 wt% 的高掺杂浓度下。此外，通过加入传统的 TADF 敏化剂，实现了 CIE 值为 (0.133, 0.109) 和 30.1% 的极高 EQE 的深蓝色 OLED。这些发现为开发具有快速三线态上转换和抑制自聚集的高效深蓝 MR-TADF 发射器的设计策略提供了见解。

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Dense Local Triplet States and Steric Shielding of a Multi-Resonance TADF Emitter Enable High-Performance Deep-Blue OLEDs

Multi-resonance thermally activated delayed fluorescence (MR-TADF) molecules based on boron and nitrogen atoms are emerging as next-generation blue emitters for organic light-emitting diodes (OLEDs) due to their narrow emission spectra and triplet harvesting properties. However, intermolecular aggregation stemming from the planar structure of typical MR-TADF molecules that leads to concentration quenching and broadened spectra limits the utilization of the full potential of MR-TADF emitters. Herein, a deep-blue MR-TADF emitter, pBP-DABNA-Me, is developed to suppress intermolecular interactions effectively. Furthermore, photophysical investigation and theoretical calculations reveal that adding biphenyl moieties to the core body creates dense local triplet states in the vicinity of S₁ and T₁ energetically, letting the emitter harvest excitons efficiently. OLEDs based on pBP-DABNA-Me show a high external quantum efficiency (EQE) of 23.4% and a pure-blue emission with a Commission Internationale de L'Eclairage (CIE) coordinate of (0.132, 0.092), which are maintained even at a high doping concentration of 100 wt%. Furthermore, by incorporating a conventional TADF sensitizer, deep-blue OLEDs with a CIE value of (0.133, 0.109) and an extremely high EQE of 30.1% are realized. These findings provide insight into design strategies for developing efficient deep-blue MR-TADF emitters with fast triplet upconversion and suppressed self-aggregation.

更新日期：2022-10-12

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