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Keywords:

  • iridium(III) complexes;
  • electronic structure;
  • absorption and emission properties;
  • density functional method

The electronic structures and photophysical properties of five iridium(III) complexes Ir(tfmppy)2(tpip) (1), Ir(dfppy)2(tpip) (2), Ir(afCNppy)2(tpip) (3), Ir(CNpyN3)2(tpip) (4), and Ir(2fphpta)2(tpip) (5) [where tfmppy = 4-trifluoromethylphenylpyridine; dfppy =4,6-difluorophenylpyridine; afCNppy = 6-fluoro-4-octyloxy-5-cyano-phenylpyridine; CNpyN3 = 2-(4-cyano-phenyl)-[1,2,3]-triazole; 2fphpta=2-(2,6-difluoro-phenyl-[1,2,4]-triazol-3-yl)-pyridine; tpip=tetraphenylimido-diphosphinate] have been investigated by using density functional theory (DFT) methods and time-dependent DFT ones, aiming at elucidating the influences of different substituents and cyclometalated ligands on the emission properties and quantum yield. The calculated results revealed that the different substituents in 1-3 have a great influence on the energy levels, in particular highest occupied molecular orbital. Meanwhile, we have also get a further insight into the reason for different phosphorescence quantum yields of the studied complexes. The higher quantum yield (Φ) reported for 1 was found to be closely related to both its smaller S1–T1 splitting energy ( inline image) and larger transition electric dipole moment ( inline image) upon the S0 [RIGHTWARDS ARROW] S1 transition. Complex 5 is expected to be a potential candidate for blue-emitting material with good organic light-emitting diodes performances. We propose that the optical properties of this class of materials can be tuned by the modifications of the cyclometalated ligands. © 2013 Wiley Periodicals, Inc.