title: Syntheses, photoluminescence, and electroluminescence of a series of iridium complexes with trifluoromethyl-substituted 2-phenylpyridine as the main ligands and tetraphenylimidodiphosphinate as the ancillary ligand.
abstract: Five bis-cyclometalated iridium complexes with tifluoromethyl-substituted 2-phenylpyridine (ppy) at different positions of its phenyl group as the main ligands and tetraphenylimidodiphosphinate (tpip) as the ancillary ligand, 2-6 (1 is a trifluoromethyl-free complex), were prepared, and their X-ray crystallography, photoluminescence, and electrochemistry were investigated. The number and positions of trifluoromethyl groups at the phenyl ring of ppy greatly affected the emission spectra of Ir(3+) complexes, and their corresponding emission peaks at 533, 502, 524, 480, and 542 nm were observed at room temperature, respectively. Constructed with complexes 2-6 as the emitters, respectively, the organic light-emitting diodes (OLEDs) with the structure of indium-tin oxide/1,1-bis[4-(di-p-tolylamino)phenyl]cyclohexane (30 nm)/Ir (x wt %):bis[3,5-bis(9H-carbazol-9-yl)phenyl]diphenylsilane (15 nm)/1,3,5-tris(1-phenyl-1H-benzo[d]imidazol-2-yl)phenyl (45 nm)/LiF (1 nm)/Al (100 nm) showed good performances. Particularly, device G4 based on 4-trifluoromethyl-substituted complex 4 with x = 8 wt % obtained a maximum luminance of over 39000 cd m(-2) and maximum luminance efficiency (η(L)) and power efficiency (η(p)) of 50.8 cd A(-1) and 29.0 lm W(-1), respectively. The results suggested that all of the complexes 2-6 would have potential applications in OLEDs.
authors.affiliation: State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, People's Republic of China.
authors.forename: Qiu-Lei
authors.initials: QL
authors.lastname: Xu
authors.forename: Cheng-Cheng
authors.initials: CC
authors.lastname: Wang
authors.forename: Tian-Yi
authors.initials: TY
authors.lastname: Li
authors.forename: Ming-Yu
authors.initials: MY
authors.lastname: Teng
authors.forename: Song
authors.initials: S
authors.lastname: Zhang
authors.forename: Yi-Ming
authors.initials: YM
authors.lastname: Jing
authors.forename: Xu
authors.initials: X
authors.lastname: Yang
authors.forename: Wei-Nan
authors.initials: WN
authors.lastname: Li
authors.forename: Chen
authors.initials: C
authors.lastname: Lin
authors.forename: You-Xuan
authors.initials: YX
authors.lastname: Zheng
authors.forename: Jing-Lin
authors.initials: JL
authors.lastname: Zuo
authors.forename: Xiao-Zeng
authors.initials: XZ
authors.lastname: You