title: Blue to true-blue phosphorescent Ir(III) complexes bearing a nonconjugated ancillary phosphine chelate: strategic synthesis, photophysics, and device integration.
abstract: We report the design and synthesis of Ir(III) complexes functionalized with substituted pyridyl cyclometalate or azolate chromophores, plus one newly designed nonconjugated phosphine chelate, which not only greatly restricts its participation in the lowest-lying electronic transition but also enhances the coordination strength. These two key factors lead to fine-tuning of the phosphorescence chromaticity toward authentic blue and simultaneously suppress, in part, the nonradiative deactivation. This conceptual design presents a novel strategy in achieving heretofore uncommon, high-efficiency blue and true-blue phosphorescence. The fabrication of the organic light-emitting devices (OLEDs) employing phosphorescent dopants [Ir(dfpbpy)(2)(P(wedge)N)] (1b) and [Ir(fppz)(2)(P(wedge)N)] (3) was successfully made, for which the abbreviations (dfpbpy)H, (fppz)H, and (P(wedge)N)H represent 2-(4,6-difluorophenyl)-4-tert-butylpyridine, 3-(trifluoromethyl)-5-(2-pyridyl)pyrazole, and 5-(diphenylphosphinomethyl)-3-(trifluoromethyl)pyrazole, respectively. Of particular interest is the 3-doped OLEDs, which exhibit remarkable maximum efficiencies of 6.9%, 8.1 cd A(-1), and 4.9 lm W(-1), together with a true-blue chromaticity CIE(x,y) = 0.163, with 0.145 recorded at 100 cd m(-2).
authors.affiliation: Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan.
authors.forename: Yuan-Chieh
authors.initials: YC
authors.lastname: Chiu
authors.forename: Yun
authors.initials: Y
authors.lastname: Chi
authors.forename: Jui-Yi
authors.initials: JY
authors.lastname: Hung
authors.forename: Yi-Ming
authors.initials: YM
authors.lastname: Cheng
authors.forename: Ya-Chien
authors.initials: YC
authors.lastname: Yu
authors.forename: Ming-Wen
authors.initials: MW
authors.lastname: Chung
authors.forename: Gene-Hsiang
authors.initials: GH
authors.lastname: Lee
authors.forename: Pi-Tai
authors.initials: PT
authors.lastname: Chou
authors.forename: Chung-Chia
authors.initials: CC
authors.lastname: Chen
authors.forename: Chung-Chih
authors.initials: CC
authors.lastname: Wu
authors.forename: Hsi-Ying
authors.initials: HY
authors.lastname: Hsieh