Theoretical study on a series of Blue-Green Ir(III) complexes used in OLED

Here six phosphorescent heteroleptic cyclometalated Ir (III) complexes were theoretically designed to identify some suitable OLED materials. (fppzb)2Ir(acac), (fppzb)2Ir(tpip), (dfbdp)2Ir(fppzb), (F-fppzb)2Ir(acac), (F-fppzb)2Ir(tpip), and (dfbdp)2Ir(F-fppzb) were studied via density functional theory (DFT) and time-dependent density functional theory (TD-DFT) methods. Here, acac denotes acetylacetonate, tpip denotes tetraphenylimido-diphosphinate, fppzb denotes 4-tert-butyl-2-(5-(trifluoromethyl)-4H-pyrazol-3-yl) pyridine and F-fppzb denotes 4-tert-butyl-2-(5-fluoro-4H-pyrazol-3-yl) pyridine. Further, we discuss the value of these materials from the electronic structure, spectral properties, ionisation potentials, electron affinities, and application prospects of the complexes. We hope that these light-emitting materials contribute to the OLED sector. This theoretical study included the energy transfer mechanism of the complexes with acac and tpip substituents as auxiliary ligands: We analyzed the possibilities and inevitability of the results in the experiments as well as evaluated the underlying mechanism for these materials’ low-efficiency roll-off.