Benzylsulfonyl functionalized phenylpyridine iridium(III) complexes with tunable light emission color: A density functional theory study

Quantum-chemistry calculations are performed to study the electronic structures, absorption, phosphorescent, and electroluminescent properties of three color tunable Ir(III) complexes with benzylsulfonyl substituents. The calculated results reveal that substituents para to the metal have a larger impact on the emission (1), while meta to the metal its impact is weak (2 and 3). For 1 and 3, the higher efficiencies result mainly from the increased metal-to-ligand charge transfer 3(MLCT)% and the protecting effect of substituents at the periphery of the complexes. In contrast, the lower efficiency of 2 mainly results from the exposure of its luminescent core to the surrounding environment together with the smaller gap between the metal centered and MLCT states. Furthermore, the potential electroluminescent properties of these complexes in organic light-emitting diodes are also investigated.