Efficient blue-emitting Ir(III) complexes with phenyl-methyl-benzimidazolyl and picolinate ligands: A DFT and time-dependent DFT study

摘要

The series of heteroleptic cyclometalated Ir(III) complexes for organic light-emitting display application have been investigated theoretically to explore their electronic structures and spectroscopic properties. The geometries, electronic structures, and the lowest-lying singlet absorptions and triplet emissions of Ir-(pmb)_3 and theoretically designed models Ir-(Rpmb)_2pic were investigated with density functional theory (DFT)-based approaches, where pmb = phenyl-methyl-benzimidazolyl, pic = picolinate, and R = H/F. Their structures in the ground and excited states have been optimized at the DFT/B3LYP/LANL2DZ and TDDFT/B3LYP/LANL2DZ levels, and the lowest absorptions and emissions were evaluated at B3LYP and M062X level of theory, respectively. The mobility of holes and electrons were studied computationally based on the Marcus theory. Calculations of ionization potentials were used to evaluate the injection abilities of holes into these complexes. The reasons for the higher electroluminescence efficiency and phosphorescence quantum yields in Ir-(Rpmb)_2pic than in Ir-(pmb) _3 have been investigated. The designed moleculars are expected to be highly emissive in pure-blue region.