Theoretical study of the high intersystem spin crossing (ISC) ability of a series of iridium complexes with low efficiency roll-off properties

A series of heteroleptic cyclometalated Ir(III) complexes for OLEDs application have been investigated theoretically to explore their electronic structures and spectroscopic properties. The geometries, electronic structures, lowest-lying singlet absorptions, and triplet emissions of (pdbi)(2)Ir(acac), (F-pdbi)(2)Ir(acac), (pdbi)(2)Ir(dpis), (F-pdbi)(2)Ir(dpis), (pdbi)(2)Ir(tpip), and (F-pdbi)(2)Ir(tpip) were investigated with density function theory (DFT) and time-dependent density functional theory (TD-DFT), where pdbi denotes 1-(4-fluorophenyl)-5-methyl-3-phenyl-2,3-dihydro-1H-1,3-benzodiazole, acac denotes acetylacetonate, dpis denotes diphenylimidodisilicate, and tpip denotes tetraphenylimido-diphosphinate. In addition, we analyzed the spin-orbit coupling constant of these six complexes, and the results showed that the six complexes have a high ability of interlinear scampering. We hope this research can serve as a reference for practical experimental synthesis aspects.