Zhang Yanxin, Qiao Juan
Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Department of Chemistry, Tsinghua University, Beijing 100084, P. R. China.
Center for Flexible Electronics Technology, Tsinghua University, Beijing 100084, P. R. China.
iScience. 2021 Jul 17;24(8):102858. doi: 10.1016/j.isci.2021.102858. eCollection 2021 Aug 20.
Organic light-emitting diodes (OLEDs) have become popular displays from small screens of wearables to large screens of televisions. In those active-matrix OLED displays, phosphorescent iridium(III) complexes serve as the indispensable green and red emitters because of their high luminous efficiency, excellent color tunability, and high durability. However, in contrast to their brilliant success in the visible region, iridium complexes are still underperforming in the near-infrared (NIR) region, particular in poor luminous efficiency according to the energy gap law. In this review, we first recall the basic theory of phosphorescent iridium complexes and explore their full potential for NIR emission. Next, the recent advances in NIR-emitting iridium complexes are summarized by highlighting design strategies and the structure-properties relationship. Some important implications for controlling photophysical properties are revealed. Moreover, as promising applications, NIR-OLEDs and bio-imaging based on NIR Ir(III) complexes are also presented. Finally, challenges and opportunities for NIR-emitting iridium complexes are envisioned.
有机发光二极管（OLED）已成为从可穿戴设备的小屏幕到电视大屏幕的流行显示屏。在那些有源矩阵OLED显示屏中，磷光铱（III）配合物由于其高发光效率、出色的颜色可调性和高耐久性而成为不可或缺的绿色和红色发光体。然而，与它们在可见光区域的辉煌成功形成对比的是，铱配合物在近红外（NIR）区域仍然表现不佳，特别是根据能隙定律，其发光效率很低。在这篇综述中，我们首先回顾磷光铱配合物的基本理论，并探索它们在近红外发射方面的全部潜力。接下来，通过突出设计策略和结构-性质关系，总结了近红外发光铱配合物的最新进展。揭示了一些控制光物理性质的重要意义。此外，作为有前景的应用，还介绍了基于近红外铱（III）配合物的近红外OLED和生物成像。最后，展望了近红外发光铱配合物面临的挑战和机遇。
