DFT and Time-dependant DFT Investigation of eLectronic Structure, Phosphorescence and Electroluminescence Properties of Iridium (III) Quinoxaline Complexes

Quantum-chemistry study was explored to investigate the electronic structures, absorption and phospho- rescence mechanism, as well as electroluminescence (EL) properties of three red-emitting Ir(III) complexes, (fpmqx)2Ir(L) {fpmqx=2-(4-fluorophenyl)-3-methyl-quinoxaline; L=triazolylpyridine (trz) (1); L=picolinate (pic) (2) and L=acetylacetonate (acac) (3)}. The calculated results show that the HOMO distribution for 1 is mainly localized on trz moiety due to its stronger π-electron acceptor ability, and HOMO for 2 and 3 is the combination of Ir d- and phenyl ring π-orbital. The higher phos- phorescence yields and differences among 1-3 are investigated in this paper. In addition, the reasons of higher EL efficiency of 2 than 1 and 3 have been rationalized.