Blue-Emitting Iridium(III) Complexes for Light-Emitting Electrochemical Cells: Advances, Challenges, and Future Prospects

Light-emitting electrochemical cells (LECs) are one of the most promising technologies for solid-sate lighting. Among them, LECs based on phosphorescent iridium(III) complexes have attracted significant research interest in the past 15 years, because of their high efficiency and tunable emission color across the entire visible spectrum. To fabricate white LECs for lighting, high-performance blue LECs are the first prerequisite. Huge efforts have been devoted to improving the performances of blue LECs based on iridium(III) complexes either by developing new blue-emitting complexes or by engineering the devices. Nevertheless, blue LECs have still shown much lower performances (brightness, efficiency, stability, etc.) compared to the red, orange-red, yellow, and green counterpart devices. In particular, a single blue LEC with satisfactory blue-color purity, high efficiency, and high stability is still missing. Here, the advances in blue-emitting iridium(III) complexes for LECs and the device engineering on LECs using the complexes are reported. The challenges ahead are discussed, and future prospects are outlined.