Phenyl substitution of cationic bis-cyclometalated iridium(iii) complexes for iTMC-LEECs.

A series of seven cationic bis-cyclometalated iridium(iii) complexes of the form [(C^N)(N^N)Ir][PF] has been designed in order to examine the effect of bulky, hydrophobic phenyl substituents on the structure-property relationship of these ionic transition metal complexes (iTMCs) in light-emitting electrochemical cells (LEECs). Capping phenyl substituents on the cyclometalating and ancillary ligands allows for individual tuning of the HOMO and LUMO energy levels, respectively, yielding an emission range from yellow to red. The complexes in this series exhibit increased quantum yields, up to 70% higher than the unoptimized, archetypal [(2-phenylpyridine)(2,2'-bipyridine)Ir][PF].