title: Fluorenylpyridine-derived iridium complexes for electrophosphorescent light-emitting diodes.
abstract: To develop efficient emitting materials for organic light-emitting diodes (OLEDs), a series of cyclometalated iridium complexes with 2-fluorenylpyridine-derived ligands were synthesized. Complexes 1-4 exhibited yellow to red phosphorescence with quantum yields of 0.17-0.33 in degassed CH2Cl2. Multilayered OLEDs were fabricated by using these iridium complexes as dopant materials. In the device employing complex 1 as a dopant, the maximum luminance, maximum luminance efficiency and maximum power efficiency were 15600 cd/m2 at 14 V, 12.8 cd/A, and 8.94 Im/W, respectively, at the CIE coordinates of (0.648, 0.350), which is close to the saturated red emission. The electron-withdrawing carbonyl substituent groups affected markedly the EL performances of fluorenylpyridine-derived iridium complexes as red emitting materials.
authors.affiliation: Department of Chemistry, Sungkyunkwan University, Suwon 440-746, Korea.
authors.forename: Kum Hee
authors.initials: KH
authors.lastname: Lee
authors.forename: Jin Ho
authors.initials: JH
authors.lastname: Kim
authors.forename: Ji Hyun
authors.initials: JH
authors.lastname: Seo
authors.forename: Young Kwan
authors.initials: YK
authors.lastname: Kim
authors.forename: Seung Soo
authors.initials: SS
authors.lastname: Yoon