AIE-active Pt(II) complexes based on a three-ligand molecular framework for high performance solution-processed OLEDs
AIE-active Pt(II) complexes based on a three-ligand molecular framework for high performance solution-processed OLEDs
复制标题
基于三配体分子框架的 AIE 活性 Pt(II) 配合物，用于高性能溶液加工 OLED
DOI：
10.1016/j.cej.2022.137457
复制
发表时间：
2022
影响因子：
15.1
通讯作者：
Wai-Yeung Wong
中科院分区：
文献类型：
--
作者：
Yuanhui Sun;Chengyun Zhu;Siqi Liu;Wentai Wang;Xi Chen;Guijiang Zhou;Xiaolong Yang;Wai-Yeung Wong
• 提出了一种用于开发铂（II）配合物的三配体分子框架。
• 阐明了新型三配体铂（II）配合物的晶体结构。
• 仔细研究了每种配体对配合物性质的影响。
• 溶液加工的纯黄色有机发光二极管实现了24.2%的创纪录外量子效率。环金属化铂（II）配合物是制造高性能有机发光二极管最具竞争力的发光材料之一。通过改变配体结构可以方便地调控环金属化铂（II）配合物的性质。然而，由于导致具有一种或两种配体的铂（II）配合物的典型设计方式，传统的环金属化铂（II）配合物总是具有刚性平面结构，并且容易形成紧密堆积，导致发射光谱改变和色纯度降低。此外，将吸电子基团和给电子基团同时引入一个分子以改善电子和空穴注入/传输过程的平衡也相对困难或繁琐。在这项工作中，我们提出了一种由一个双齿配体和两个独立的单齿配体组成的新分子框架。基于这种三配体分子框架，合成了19种铂（II）配合物，以研究每种配体对发射以及电荷注入/传输性质的影响。这些三配体铂（II）配合物中的一些显示出令人印象深刻的聚集诱导发射特性、高光致发光量子产率以及改善的空穴和电子注入/传输能力平衡。因此，溶液加工的磷光有机发光二极管呈现出非常纯的黄色发射，具有极高的外量子效率（EQE），高达24.2%，这是溶液加工方法制造的纯黄色有机发光二极管所报道的最高EQE。这项研究提出了一种新的分子框架，展示了其在开发高性能电致发光材料方面的有前景的潜力，并为如何设计分子结构以获得所需性质提供了清晰的线索。
• A three-ligand molecular framework for developing Pt(II) complex is proposed. • The crystal structures of new three-ligand Pt(II) complexes are clarified. • The effect of each ligand on the properties of the complex is carefully studied. • Solution-processed pure yellow OLED achieves a record EQE of 24.2%. Cyclometallated Pt(II) complexes are one of the most competitive light-emitting materials for fabricating high-performance OLEDs. The properties of cyclometallated Pt(II) complexes can be conveniently manipulated by altering the ligand structures. However, because of the typical design fashion which leads to Pt(II) complexes with one or two ligands, the conventional cyclometallated Pt(II) complexes always have a rigid planar structure and are prone to form close packing, resulting in a change in the emission spectrum and a decrease in the color purity. Besides, it is also relatively difficult or cumbersome to simultaneously introduce electron-withdrawing and electron-donating groups into one molecule to improve the balance of electron and hole injection/transport process. In this work, we propose a new molecular framework which consists of one bidentate ligand and two independent monodentate ligands. Based on this three-ligand molecular framework, nineteen Pt(II) complexes are synthesized to investigate the influence of each ligand on the emission as well as the charge injection/transport properties. Some of these three-ligand Pt(II) complexes display impressive aggregation-induced emission properties, high photoluminescent quantum yields and improved balance of hole and electron injection/transport ability. Consequently, solution-processed phosphorescent OLEDs exhibit very pure yellow emissions with a remarkably high external quantum efficiency (EQE) reaching up to 24.2%, which is the highest EQE reported for pure yellow OLEDs fabricated with the solution-processed method. This study proposes a new molecular framework, demonstrates its promising potential for developing high-performance electroluminescent materials and provides clear clues on how to engineer molecular structure for desired properties.