Novel solid state emitting iridium complexes with reduced phosphorescence-self-quenching triggered by steric blocking phosphine ligands

In this paper, we report two easily-synthesized Ir(III) complexes equipped with steric blocking phosphine ligands of bis(2-(diphenylphosphanyl)phenyl) (POP) and triphenylphosphane (PPh₃), Ir-POP and Ir-PPh₃. Their crystal structures, electronic nature, photophysical properties, and phosphorescence self-quenching mechanism are discussed in detail. It is found that the thermally activated intermolecular interaction is responsible for the phosphorescence self-quenching. The introduction of steric blocking ligands into Ir(III) complexes can efficiently suppress the phosphorescence self-quenching in solid state. We successfully realize a solid state emission peaking at 494 nm, with a long excited state lifetime of 15 μs and a high photoluminescence quantum yield of 0.17.