Highly efficient blue phosphorescent organic light-emitting diodes with low operation voltage. (October 2021)

• Record Type: Journal Article
• Authors: Zhu, Qi; Zhou, Liang; Liu, Weiqiang; Cui, Yingjie; Wu, Ruixia; Wang, Jiahai; Duanmu, Qingduo
• Is Part Of: Optics & laser technology. Volume 142(2021)
• Publication Date: 2021-10
• Subjects: Organic light-emitting diodes -- Blue emission -- Iridium complex -- Efficiency roll-off; Optics -- Periodicals; Lasers -- Periodicals; Electronic journals; 621.366
• DOI: 10.1016/j.optlastec.2021.107229
• Languages: English
• ISSNs: 0030-3992

Abstract

Graphical abstract: Electroluminescent (EL) performances of phosphorescent emitter iridium(III) bis(4′, 6′-difluorophenylpyridinato)tetrakis(1-pyrazolyl)borate (FIr6) were significantly improved by designing double light-emitting layers device structure with 4, 4′, 4′-tris(N-carbazolyl)triphenylamine (TcTa) and 2, 6-bis(3-(9Hcarbazol-9-yl)phenyl) phyridine (26DCzPPy) as host materials. Highlights: Efficient deep-blue electroluminescent devices were designed and fabricated. Highly efficient phosphorescent device with slow efficiency roll-off was realized. Well matched energy level of host materials helps to reduce driving voltage. Abstract: In this work, we report an efficient blue organic electroluminescent device based on phosphorescent emitter iridium(III) bis(4′, 6′-difluorophenylpyridinato)tetrakis(1-pyrazolyl)borate (FIr6), which displayed excellent thermal stability. To balance carriers' distribution and reduce operation voltage, double light-emitting layers device structure was designed by selecting 4, 4′, 4′-tris(N-carbazolyl)triphenylamine (TcTa) and 2, 6-bis(3-(9Hcarbazol-9-yl)phenyl)phyridine (26DCzPPy) as host materials because of their stepwise energy levels. By optimizing the doping concentration of FIr6 to be 26 wt%, well balanced carriers' distribution on emitter molecules and broadening recombination zone were realized. Finally, high performance blue device with slow efficiency roll-off and high current efficiency up to 56.83 cd/A (obtained at 700 cd/m 2 ) was realized. At the certain brightness of 1000 (3.9 V) and 5000 cd/m 2 (4.8 V), the same device retained efficiencies of 56.33 and 51.45 cd/A, respectively.