A series of pure orange-yellow iridium complexes with low efficiency roll-off: A computational study

The electronic structures and spectroscopic properties of heteroleptic cyclometalated iridium(III) complexes were investigated. The geometries, electronic structures, and the lowest-lying excited states of (DBQ)2Ir(acac) and (MDQ)2Ir(acac) were investigated via density functional theory-based approaches. A series of designed models of (DBQ)2Ir(dpis), (DBQ)2Ir(tpip), (MDQ)2Ir(dpis) and (MDQ)2Ir(tpip) was also calculated for comparison. The structures in the ground and excited states were optimized via B3LYP method. The lowest absorptions and emissions spectra were evaluated via TD-B3LYP and TD-PBE1PBE methods. The computational results reveal that the emission peaks of the designed complexes are at around 585―640 nm, which belong to the orange-yellow wavelength. The frontier molecular orbital properties indicate that the Ir(III) complexes have low efficiency roll-off.