A theoretical study of a series of iridium complexes with methyl or nitro-substituted 2-(4-fluorophenyl)pyridine ligands with the low-efficiency roll-off performance

A series metal iridium complexes were calculated using the method of DFT and TD-DFT under Gaussian 09 software. H atoms on the N counter in 2-(4-fluorophenyl)pyridine were replaced with methyl and nitro groups, respectively, to obtain two main ligands CFM(2-(4-fluorobrobenyl)-4-methylpyridine) and CFN(2-(4-fluoro-brobenyl)-4-nitropyridine), then we obtained six complexes: (CFM)2Ir(acac), (CFM)2Ir(tpip), (CFM)3Ir, (CFN)2Ir (acac), (CFN)2Ir(tpip) and (CFN)3Ir, Where acac is represented as pentane-2, 4-dione, tpip as tetraphenylimido-diphosphinate. The electronic structure, the lowest singlet absorption, the triple excited states as well as the emission spectrum are also theoretically studied.