| 초록 |
The ionic iridium complexes, [Ir(ppy)2(EP–Imid)]PF6 (Complex 1) and [Ir(dfppy)2(EP–Imid)]PF6 (Complex 2) are used as the light-emitting material for the fabrication of light-emitting electrochemical cells (LECs). These complexes have been synthesized, employing 2–(4–ethyl–2–pyridyl)–1H–imidazole (EP–Imid) as the ancillary ligand, 2–phenylpyridine (ppy) and 2–(2,4–difluorophenyl)pyridine (dfppy) as the cyclometalated ligands, which were characterized by various spectroscopic, photophysical and electrochemical methods. The photoluminescence (PL) emission spectra in acetonitrile show blue–green and blue light emission for Complex 1 and 2 respectively. However, LECs incorporating these complexes resulted in green (522 nm) light emission for Complex 1 with the CIE coordinates of (0.33, 0.56) and blue–green (500 nm) emission for Complex 2 with the CIE coordinates of (0.24, 0.44). Using Complex 1, a maximum luminance of 1191 cd m-2 and current efficiency of 1.0 cd A-1 are obtained while that of Complex 2 are 741 cd m-2 and 0.88 cd A-1 respectively. |
