Highly efficient green-emitting electrophosphorescent iridium complexes with enhanced steric hindrance.
Two novel iridium complexes, bis[2-(1,1',2',1"-terphen-3-yl)pyridinato-C,N]iridium(III) (acetylacetonate) (tphpy)2Ir(acac) and bis[2-(5,5,8,8-tetramethyl-5,6,7,8-tetrahydronaphthalen-2-yl)pyridinato-C,N]- iridium(III) (acetylacetonate) (tmhppy)2Ir(acac), were synthesized and characterized using the various spectroscopic methods. Multilayered, organic light-emitting diodes (OLEDs) were fabricated by using the complexes as dopant materials. A maximum luminance of 57840 cd/m2 at 14 V and a luminance efficiency of 40 cd/A at 20 mA/cm2 were achieved. The peak wavelength of the electroluminescence was at 527 nm with CIE coordinates of (0.34, 0.63), and the device showed a stable color chromaticity at various voltages. Significantly improved operational lifetime was achieved using (tphpy)2Ir(acac) and (tmhppy)2Ir(acac) compared to that using (ppy)2Ir(acac), at the same doping level.
Lee
Kum Hee
KH
Department of Chemistry Sungkyunkwan University, Suwon 440-746, Korea.
Seo
Ji Hyun
JH
Kim
Young Kwan
YK
Yoon
Seung Soo
SS