title: A robust yellow-emitting metallophosphor with electron-injection/-transporting traits for highly efficient white organic light-emitting diodes.
abstract: With the aim of endowing triplet emitters in the development of organic light-emitting devices (OLEDs) with electron-injection/-transporting (EI/ET) features, the phenylsulfonyl moiety was introduced into the phenyl ring of a 2-phenylpyridine (Hppy) ligand and the yellow phosphorescent heteroleptic iridium(III) complex 1 was developed. It was shown that the SO(2)Ph unit could provide EI/ET character to 1, as indicated from both electrochemical and computational data. Complex 1 is a promising yellow-emitting material for both monochromatic OLEDs and white OLEDs (WOLEDs). The outstanding electronic traits associated with 1, coupled with careful device design, afforded very attractive electroluminescent performances for two-element WOLEDs, including a low turn-on voltage of less than 3.7 V, a maximum brightness of 48,000 cd m(-2), an external quantum efficiency of 13.0%, a luminance efficiency of 34.7 cd A(-1), and a power efficiency of 24.3 Lm W(-1). In addition, a good color rendering index (CRI) of about 74, a stable white color with a Commission Internationale de L'Eclairage (CIE(x,y)) variation of Δ(x, y) < ±(0.02, 0.02), and a correlated color temperature higher than 5130 K were obtained. These encouraging results indicate the potential of these WOLEDs as good candidates for warm indoor lighting sources, as well as the critical contribution of such key EI/ET properties to triplet emitters to advance new OLED research.
authors.affiliation: MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, and Department of Chemistry, Faculty of Science, Xi'an Jiao Tong University, Xi'an 710049, PR China. zhougj@mail.xjtu.edu.cn
authors.forename: Guijiang
authors.initials: G
authors.lastname: Zhou
authors.forename: Xiaolong
authors.initials: X
authors.lastname: Yang
authors.forename: Wai-Yeung
authors.initials: WY
authors.lastname: Wong
authors.forename: Qi
authors.initials: Q
authors.lastname: Wang
authors.forename: Si
authors.initials: S
authors.lastname: Suo
authors.forename: Dongge
authors.initials: D
authors.lastname: Ma
authors.forename: Jikang
authors.initials: J
authors.lastname: Feng
authors.forename: Lixiang
authors.initials: L
authors.lastname: Wang