Zhang Youming, Kao Hao-Che, Shi Chao, Wu Chengjun, Zhu Minrong, Li Kai, Wu Chung-Chih, Yang Chuluo
Guangdong Research Center for Interfacial Engineering of Functional Materials, College of Materials Science and Engineering, Shenzhen University, 518055, Shenzhen, P. R. China.
Department of Electrical Engineering and, Graduate Institute of Photonics and Optoelectronics, National Taiwan University, 10617, Taipei, Taiwan.
Chemistry. 2022 Jan 10;28(2):e202103543. doi: 10.1002/chem.202103543. Epub 2021 Nov 23.
A series of [-2, -1, 0] charged-ligand based iridium(III) complexes of [Ir(bph)(bpy)(acac)] (1), [Ir(bph)(2MeO-bpy)(acac)] (2), [Ir(bph)(2CF -bpy)(acac)] (3), [Ir(bph)(bpy)(2 Bu-acac)] (4) and [Ir(bph)(bpy)(CF -acac)] (5), which using biphenyl as dianionic ligand [-2], acetylacetone (or its derivatives) as monoanionic ligand [-1], and 2,2'-bipyridine (or its derivatives) as neutral ligand [0] were designed and synthesized. The chemical structures were well characterized. All of the ligands have simple chemical structures, thus further making the complexes have excellent thermal stability and are easy to sublimate and purify. Phosphorescent characteristics with short emission lifetime were demonstrated for these emitters. Notably, all of the complexes exhibit remarkable deep red/near infrared emission, which is quite different from the reported [-1, -1, -1] charged-ligand based iridium(III) complexes. The photophysical properties of these complexes are regularly improved by introducing electron-donating or -withdrawing groups into [-1] or [0] charged-ligand. The related organic light-emitting diodes exhibited deep red/near infrared emission with acceptable external quantum efficiency and low turn-on voltage (<2.6 V). This work provides a new idea for the construction of new type phosphorescent iridium(III) emitters with different valence states of [-2, -1, 0] charged ligands, thus offering new opportunities and challenges for their optoelectronic applications.
设计并合成了一系列基于[-2, -1, 0]电荷配体的铱(III)配合物，即[Ir(bph)(bpy)(acac)] (1)、[Ir(bph)(2MeO-bpy)(acac)] (2)、[Ir(bph)(2CF -bpy)(acac)] (3)、[Ir(bph)(bpy)(2 Bu-acac)] (4)和[Ir(bph)(bpy)(CF -acac)] (5)，其中使用联苯作为二价阴离子配体[-2]，乙酰丙酮（或其衍生物）作为一价阴离子配体[-1]，2,2'-联吡啶（或其衍生物）作为中性配体[0]。对其化学结构进行了充分表征。所有配体的化学结构都很简单，这进一步使得这些配合物具有出色的热稳定性，并且易于升华和提纯。这些发光体表现出具有短发射寿命的磷光特性。值得注意的是，所有配合物都表现出显著的深红色/近红外发射，这与已报道的基于[-1, -1, -1]电荷配体的铱(III)配合物有很大不同。通过将供电子或吸电子基团引入[-1]或[0]电荷配体中，这些配合物的光物理性质得到了有规律的改善。相关的有机发光二极管表现出深红色/近红外发射，具有可接受的外量子效率和低开启电压（<2.6 V）。这项工作为构建具有[-2, -1, 0]电荷配体不同价态的新型磷光铱(III)发光体提供了新思路，从而为其光电应用带来了新的机遇和挑战。
