Light-emitting properties of cationic iridium complexes containing phenanthroline based ancillary ligand with blue-green and green emission colors

Abstract

We report here two new cationic iridium(III) complexes with phenanthroline-based ancillary ligands, [Ir(dfppy)2(dibutyl-phen)]PF6 (Complex 1) and [Ir(ppz)2(dibutyl-phen)]PF6 (Complex 2) and their uses in light-emitting electrochemical cells (LECs). The design is based on 2-(2,4-difluorophenyl)pyridine (dfppy) and 1-phenylpyrazole (ppz) as the cyclometalating ligands and 2,9-dibutyl-1,10-phenanthroline (dibutyl-phen) as the ancillary ligand. The photophysical and electrochemical properties of the complexes were studied and the results obtained were corroborated with theoretical density functional theory (DFT) calculations. LECs were fabricated incorporating each complexes which resulted in blue-green light emission (502nm) with Commission Internationale de l’Eclairage (CIE) coordinates of (0.26, 0.49) for Complex 1 and green (530nm) electroluminescence with CIE coordinates of (0.33, 0.54) for Complex 2. The luminance and the current efficiency of the LECs based on Complex 1 are 947cdm−2 and 0.25cdA−1, respectively, which are relatively higher than that of Complex 2 with a maximum luminance of 773cdm−2 and an efficiency of 0.16cdA−1.