New red electrophosphor based on Ir(III) complex of 2,3,4-triphenylquinoline

2,3,4-Triphenylquinoline (tpq) ligand and its Ir(III) complex Ir(tpq)2(acac) were prepared and their photonic properties were investigated as red electrophosphorescent material. The photoluminescence (PL) spectra of tpq and Ir(tpq)2(acac) in dichloromethane showed a peak at 450 nm and 607 nm, respectively, at room temperature. The small Stokes shift between the 3MLCT absorption and emission bands shows that Ir(tpq)2(acac) emits from a predominantly 3MLCT excited state. The theoretical calculation of the Ir(III) complex was performed by an ab initio method, and the result calculated by time dependent density functional theory (TD-DFT) showed that the Ir(III) complex underwent a strong 3MLCT transition because of the strong coupling between the 5d-orbital of Ir atom and the highest occupied molecular orbital (HOMO) of tpq ligand. Thus, it is concluded that this complex is a good candidate for a highly efficient electrophosphorescent material.