Theoretical perspective of FIrpic derivatives: relationship between structures and photophysical properties

The phosphorescent properties of a series of potential blue-emitting Ir(III) complexes (C^N)₂Ir(N^N') are studied by means of the density functional theory/time-dependent density functional theory (DFT/TDDFT). Their possibilities to be blue-emitting phosphors are theoretically evaluated by the electroluminescence (EL) performance and phosphorescence quantum yield. The effect of two different substituents attached on the difluorophenyl ring is explored by comparison of the complexes in groups I (1a-4a) and II (1b-4b). Furthermore, to explore the influence of the stronger electron-donating/withdrawing group substituted on the primary ligand, the properties of complexes 1c and 1d are estimated. All the substituents are added on the para-position of the corresponding ring. The comparable radiative rate constant (k_r) and nonradiative rate constant (k_nr) result in the similar quantum yield for complexes in two groups. Besides, the balance of the reorganization energies for complexes 2b-4b is better than others.