title: De Novo Design of Boron-Based Host Materials for Highly Efficient Blue and White Phosphorescent OLEDs with Low Efficiency Roll-Off.
abstract: Borane is an excellent electron-accepting species, and its derivatives have been widely used in a variety of fields. However, the use of borane derivatives as host materials in OLEDs has rarely reported because the device performance is generally not satisfactory. In this work, two novel spiro-bipolar hosts with incorporated borane were designed and synthesized. The strategies used in preparing these materials were to increase the spatial separation of the highest occupied molecular orbitals (HOMOs) and lowest unoccupied molecular orbitals (LUMOs) in the molecules, tune the connecting positions of functional groups, and incorporate specific functional groups with desirable thermal stability. Based on these designs, phosphorescent OLEDs with borane derivatives as hosts and with outstanding device performances were obtained. In particular, devices based on SAF-3-DMB/FIrpic exhibited an external quantum efficiency (EQE) of >25%. More encouragingly, the device was found to have quite a low efficiency roll-off, giving an efficiency of >20% even at a high brightness of 10000 cd/m(2). Furthermore, the EQE of the three-color-based (R + G + B) white OLED employing SAF-3-DMB as a host was also as high as 22.9% with CIE coordinates of (x, y) = (0.40, 0.48). At a brightness of 5000 cd/m(2), there was only a 3% decrease in EQE from its maximum value, implying a very low efficiency roll-off.
authors.affiliation: Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Institute of Functional Nano & Soft Materials (FUNSOM), Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University , Suzhou, Jiangsu 215123, P.R. China.
authors.forename: Miao-Miao
authors.initials: MM
authors.lastname: Xue
authors.affiliation: Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Institute of Functional Nano & Soft Materials (FUNSOM), Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University , Suzhou, Jiangsu 215123, P.R. China.
authors.forename: Chen-Chao
authors.initials: CC
authors.lastname: Huang
authors.affiliation: Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Institute of Functional Nano & Soft Materials (FUNSOM), Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University , Suzhou, Jiangsu 215123, P.R. China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Yuan
authors.affiliation: Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Institute of Functional Nano & Soft Materials (FUNSOM), Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University , Suzhou, Jiangsu 215123, P.R. China.
authors.forename: Lin-Song
authors.initials: LS
authors.lastname: Cui
authors.affiliation: Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Institute of Functional Nano & Soft Materials (FUNSOM), Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University , Suzhou, Jiangsu 215123, P.R. China.
authors.forename: Yong-Xi
authors.initials: YX
authors.lastname: Li
authors.affiliation: Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Institute of Functional Nano & Soft Materials (FUNSOM), Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University , Suzhou, Jiangsu 215123, P.R. China.
authors.forename: Bo
authors.initials: B
authors.lastname: Wang
authors.affiliation: Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Institute of Functional Nano & Soft Materials (FUNSOM), Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University , Suzhou, Jiangsu 215123, P.R. China.
authors.forename: Zuo-Quan
authors.initials: ZQ
authors.lastname: Jiang
authors.affiliation: Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Institute of Functional Nano & Soft Materials (FUNSOM), Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University , Suzhou, Jiangsu 215123, P.R. China.
authors.forename: Man-Keung
authors.initials: MK
authors.lastname: Fung
authors.affiliation: Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Institute of Functional Nano & Soft Materials (FUNSOM), Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University , Suzhou, Jiangsu 215123, P.R. China.
authors.forename: Liang-Sheng
authors.initials: LS
authors.lastname: Liao
keywords: borane derivatives; high efficiency; low efficiency roll-off; molecular orbital spatial separation; spiro-bipolar hosts