Recent progress in phosphorescent Ir(III) complexes for nondoped organic light-emitting diodes

Highly efficient phosphorescent organic light-emitting diodes (PHOLEDs) with simple configuration as well as low cost fabrication process have attracted much interest for both academic researches and commercial endeavors. This review provides an update on recent advances in the development Ir(III) complexes and their applications in nondoped PHOLEDs fabricated by both vacuum deposition and solution-processed approaches. The modification of chemical structures of the small molecular Ir(III) complexes and dendrimers through incorporating multiple functional moieties could effectively adjust the optical and electronic characters. These complexes typically possess reduced intermolecular aggregation, various hole and electron transporting abilities so that high-performance nondoped PHOLEDs can be developed. The corresponding structural, optical, electronic, photophysical as well as the EL properties in different colors over the whole spectral region are surveyed and highlighted. In the end, the perspectives of the development for the further trend are presented, hopefully to provide useful guidance for the research on highly efficient Ir(III) complexes and corresponding nondoped PHOLEDs. (C) 2020 Elsevier B.V. All rights reserved.