Efficient Blue-Emitting Ir(III) Complexes with Phosphine Carbanion-Based Ancillary Ligand: A DFT Study

We report a theoretical study on a series of heteroleptic cyclometalated Ir(III) complexes for OLED application. The geometries, electronic structures, and the lowest-lying singlet absorptions and triplet emissions of [(fppy)(2)Ir(III)-(PPh2Np)] (1), and theoretically designed models [(fppy)(2)Ir(III)(PH2Np)] (2) and [(fppy)(2)Ir(III)Np](-)(3) were investigated with density functional theory (DFT)-based approaches, where, fppyH = 4-fluorophenyl-pyridine and NpH = naphthalene. The ground and excited states were, respectively, optimized at the M062X/LanL2DZ;6-31G* and CIS/LanL2DZ:6-31G* level of theory within CH2Cl2 solution provided by PCM. The lowest absorptions and emissions were evaluated at M062X/Stuttgart;cc-pVTZ;cc-pVDZ level of theory. Though the lowest absorptions and emissions were all attributed as the ligand-based charge transfer transition with slight metal-to-ligand charge transfer transition character, the subtle differences in geometries and electronic structures result in the different quantum yields and versatile emission color. The newly designed molecular 3 is expected to be highly emissive in deep blue region.