Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518060, P. R. China.
Adv Mater. 2023 Jul;35(28):e2300510. doi: 10.1002/adma.202300510. Epub 2023 May 31.
Fabricating solution-processible host material for thermally activated delayed fluorescence (TADF) emitter remains a formidable challenge for organic light-emitting diodes (OLEDs). In this work, two new host materials, namely 3CzAcPy and 9CzAcPy, are found to exhibit high triplet energy levels, high thermal stability, and excellent film morphology from a solution process. An in-depth analysis on the photophysical data and device performance reveals the isomeric effect of the host materials has a significant impact not only on the host properties, but also on the host-dopant interactions and thus the performance of the resulting solution-processed TADF OLEDs. Impressively, the new hosts are proven to be suitable for both donor-acceptor type and multi-resonance TADF emitters, achieving state-of-the-art device performance. By using the new host 9CzAcPy, solution-processed OLED based on a donor-acceptor TADF emitter of DPAC-PCN, a maximum external quantum efficiency (EQE) of 29.5% is achieved, and solution-processed narrowband OLED based on a multiple-resonance TADF emitter of BN-CP1 acquires a maximum EQE of 26.6%. These efficiencies represent the highest values among the solution-processed TADF OLEDs. This study highlights the significance of host-dopant interactions in modulating the electroluminescence performance of TADF emitters, and provides an effective design principle for solution-processible host materials.
为热激活延迟荧光（TADF）发射器制造溶液处理型主体材料仍然是有机发光二极管（OLED）的一个巨大挑战。在这项工作中，发现两种新的主体材料，即 3CzAcPy 和 9CzAcPy，具有高三重态能级、高热稳定性和从溶液处理获得的优异膜形态。对光物理数据和器件性能的深入分析表明，主体材料的异构效应不仅对主体性质，而且对主体-掺杂剂相互作用以及由此产生的溶液处理 TADF OLED 的性能都有重大影响。令人印象深刻的是，这些新的主体材料被证明适合于供体-受体型和多共振 TADF 发射器，实现了最先进的器件性能。通过使用新的主体 9CzAcPy，基于 DPAC-PCN 的供体-受体 TADF 发射器的溶液处理 OLED 实现了 29.5%的最大外量子效率（EQE），而基于 BN-CP1 的多共振 TADF 发射器的溶液处理窄带 OLED 获得了 26.6%的最大 EQE。这些效率值在溶液处理 TADF OLED 中代表了最高值。这项研究强调了主体-掺杂剂相互作用在调节 TADF 发射器的电致发光性能方面的重要性，并为溶液处理型主体材料提供了有效的设计原则。
