New Blue Phosphorescent Iridium Complexes with Various Ancillary Ligands Based on Fluorinated 2-Phenyl-4-Methylpyridine

Abstract

In this study, a series of new blue phosphorescent iridium(III) complexes with ligands of (CF3)2Meppy [(CF3)2Meppy = 2-(3′,5′-bis-trifluoromethylphenyl)-4-methylpyridine] were successfully synthesized and their photophysical properties were systematically investigated. To analyze color tuning effected by changing the ancillary ligands, we have measured UV-absorption and photoluminescence (PL) spectra and have theoretically calculated the iridium complexes with different ancillary ligands using computational methods. The maximum emission spectrum of Ir[(CF3)2Meppy]2(acac), Ir[(CF3)2Meppy]2(pic), Ir[(CF3)2Meppy]2(taz) and Ir[(CF3)2Meppy]2(N4) were 473.5, 472, 475 and 468 nm, respectively. However, the PL efficiency was not improved by changing the picolinate ligands with other ancillary ligands, such as triazolate or tetrazolate ions. We discuss how the ancillary ligand influences both the emission peak and the metal to ligand charge transfer (MLCT) transition efficiency.