Synthesis and Photophysical Studies of New Blue Phosphorescent Iridium Complexes of Fluorinated 2-phenyl-4-methoxypyridine

In this study, a new Ir(III) complex containing 2-(3′,5′-bistrifluoromethyl phenyl)-4-methoxypyridine have been synthesized and characterized for efficient blue organic light-emitting diodes (OLEDs). In order to tune photoluminescence (PL) spectra to a shorter wavelength, ppy ligand was fluorinated by –;CF3 and substituted by –OCH3 group. The methoxy group substituted on the 4-position of pyridyl ring as electron donating group strongly affected the lowest unoccupied molecular orbital (LUMO) and it raised the LUMO energy and increased the energy gap. The trifluoromethyl group substituted on the 3′,5′-position of phenyl ring as electron withdrawing group decreased the highest occupied molecular orbital (HOMO), and bulky CF3 groups occurs a steric hindrance of iridium complex helps decrease of self-quenching. As a result, Ir[(CF3)2OMeppy]2(acac) is more blue-shifted emission at 471 nm and strong luminescence efficiency.