Godumala Mallesham, Hwang Jinhyo, Kang Hyunchul, Jeong Ji-Eun, Harit Amit Kumar, Cho Min Ju, Woo Han Young, Park Sungnam, Choi Dong Hoon
Department of Chemistry, Research Institute for Natural Sciences, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea.
ACS Appl Mater Interfaces. 2020 Aug 5;12(31):35300-35310. doi: 10.1021/acsami.0c10293. Epub 2020 Jul 22.
Organic polymers that exhibit features pertinent to functioning as host materials for thermally activated delayed fluorescence (TADF) emitters have considerable potential in solution-processable organic light-emitting diodes (OLEDs), allowing simple, low-cost, and large-area applications. In particular, polymer hosts have superior characteristics, including facile functionality to introduce various electron donor and acceptor entities, the ability to uniformly disperse and contain small molecular dopants, and the ability to produce more smooth and homogeneous films, compared to those of their small-molecule counterparts. This manuscript describes the design and development of three new styrene-based copolymers (, , and ) bearing diphenylacridine as the electron donor and 2,12-di--butyl-7-phenyl-5,9-dioxa-13b-boranaphtho[3,2,1-]anthracene as the electron acceptor. In particular, , , and were synthesized via variations in the ratio of donor to acceptor monomers to substantiate their influence in OLED applications. With the ability of the styrene backbone of interrupting the direct electronic coupling between the adjacent electron donor and acceptor entities through non-conjugated linkages, high triplet energy can be inherited by the resulting polymers (>2.70 eV). Furthermore, these materials manifest thermal robustness through high decomposition temperatures (between 348 and 366 °C) and high glass transition temperatures (between 234 and 277 °C). Consequently, solution-processable OLEDs fabricated using the newly synthesized copolymers as host materials and the familiar t4CzIPN as a green-emissive TADF dopant deliver state-of-the-art performance with maximum external quantum efficiencies of 21.8, 22.2, and 19.7% for , , and , respectively. To our knowledge, this is, to date, the best performance reported when organic polymers are used as host materials in solution-processable TADF OLEDs. The pragmatic outcomes obtained in this study can provide useful insights into the structure-property relationship to the OLED community for the further development of efficient polymer hosts for use in solution-processable TADF OLEDs.
表现出与热激活延迟荧光（TADF）发射体的主体材料功能相关特性的有机聚合物，在溶液可加工有机发光二极管（OLED）中具有巨大潜力，可实现简单、低成本和大面积应用。特别是，与小分子主体材料相比，聚合物主体具有优异的特性，包括易于引入各种电子供体和受体实体的功能、均匀分散和容纳小分子掺杂剂的能力，以及形成更光滑和均匀薄膜的能力。本论文描述了三种新型苯乙烯基共聚物（、和）的设计与开发，它们以二苯基吖啶作为电子供体，2,12 - 二 - 丁基 - 7 - 苯基 - 5,9 - 二氧杂 - 13b - 硼萘并[3,2,1 - ]蒽作为电子受体。特别是，、和通过改变供体与受体单体的比例合成，以证实它们在OLED应用中的影响。由于苯乙烯主链能够通过非共轭键中断相邻电子供体和受体实体之间的直接电子耦合，所得聚合物能够继承较高的三线态能量（>2.70 eV）。此外，这些材料通过高分解温度（348至366°C之间）和高玻璃化转变温度（234至277°C之间）表现出热稳定性。因此，使用新合成的共聚物作为主体材料和常见的t4CzIPN作为绿色发光TADF掺杂剂制备的溶液可加工OLED，分别实现了21.8%、22.2%和19.7%的最大外量子效率，展现出了先进的性能。据我们所知，这是迄今为止在溶液可加工TADF OLED中使用有机聚合物作为主体材料所报道的最佳性能。本研究中获得的实际成果可为OLED领域的结构 - 性能关系提供有用的见解，以进一步开发用于溶液可加工TADF OLED的高效聚合物主体材料。
