Recent Advances on Blue-Emitting Iridium(III) Complexes for Light-Emitting Electrochemical Cells

Abstract

Blue light-emitting electrochemical cells (LECs) are critically important for the fabrication of white LECs toward solid-state lighting applications. During the past decade, blue-emitting iridium(III) complexes have been pursued as the emitting materials for blue LECs. In this chapter, the recent advances on blue-emitting iridium(III) complexes for LECs are discussed based on the four molecular design strategies, namely, (i) modification on the archetype complex [Ir(pp)2(bpy)]+ (Hppy is 2-phenylpyridine, bpy is 2,2’-bipyridine), (ii) using ancillary ligands beyond the bpy skeleton, (iii) using ancillary ligands with strong ligand field strength, and (iv) using cyclometalating ligands beyond the ppy skeleton. The discussion is focused on how to blue-shift the emission of the complexes, as well as the performances of the complexes in LECs. This complements Chap. 7, in which the design of iridium (III) complexes for stable, efficient, and fast LECs is described. So far, near-UV emitting complexes and LECs have been reported. Nevertheless, good color purity, high efficiency, high brightness and short response time have not been achieved in one blue LEC. Most importantly, the stability of the blue LECs should be significantly improved. With high-performance blue-emitting materials and optimized devices, it is believed that blue LECs suitable for applications will come out in the near future.