Near-infrared emitting iridium complexes: Molecular design, photophysical properties, and related applications

Yanxin Zhang; Juan Qiao

doi:10.1016/j.isci.2021.102858

Near-infrared emitting iridium complexes: Molecular design, photophysical properties, and related applications

iScience. 2021 Jul 17;24(8):102858. doi: 10.1016/j.isci.2021.102858. eCollection 2021 Aug 20.

Authors

Yanxin Zhang¹, Juan Qiao^{1

2}

Affiliations

¹ Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Department of Chemistry, Tsinghua University, Beijing 100084, P. R. China.
² Center for Flexible Electronics Technology, Tsinghua University, Beijing 100084, P. R. China.

Abstract

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.

Keywords: Optical materials; Organic chemistry; Photonics.

Publication types

Review