High-efficiency and low efficiency roll-off in white organic light-emitting diodes employing a novel blue emitter

• Published in: Organic electronics 2019-12, Vol.75, p.105375, Article 105375
• Main Authors: Sheng, Ren, Song, Jian, Li, Asu, Zhang, Fujun, Zhang, Han, Duan, Yu, Zheng, Jie, Wang, Zhiming, Chen, Ping
• Format: Article
• Language: English
• Subjects: High efficiency; Low efficiency roll-off; Novel blue fluorescence; White OLED
• ISSN: 1566-1199; 1878-5530
• DOI: 10.1016/j.orgel.2019.105375

A novel blue fluorophore of 3,40-bis(1-phenyl-phenanthro[9,10-d]-imidazol-2-yl) biphenyl (L-BPPI) was firstly utilized as the blue fluorescent emitter to fabricate highly efficient fluorescent/phosphorescent hybrid white organic light-emitting diodes (WOLEDs). By introducing a mixed interlayer between the blue fluorescent and orange phosphorescent region, two-color WOLED exhibited CIE coordinates close to the equal energy point of (0.33, 0.33) with peak efficiencies of 40.7 cd/A and 26.8 lm/W. And fairly stable white emission spectra were realized owing to the well control of exciton distribution and charge transport balance. Moreover, three-color WOLED was achieved when an ultrathin red phosphorescent emitter was inserted. The result device with reduced efficiency roll-off showed peak efficiencies of 35.3 cd/A and 25.4 lm/W. [Display omitted] •The performance of non-doped deep blue OLEDs based on L-BPPI achieved maximum efficiency of 3.82 cd/A (2.89 lm/W) and superior charge transport property.•The two-color white OLED (WOLED) exhibits CIE coordinates close to the equal energy point of (0.33, 0.33) and a peak efficiency of 40.7 cd/A (26.8 lm/W). The three-color WOLED device shows a peak efficiency of 35.3 cd/A (25.4 lm/W) and low efficiency roll-off.•The interlayer structure can be acted as a charge switch, which can manipulate the EL performance of devices by adjusting the mixed ratio.•These results demonstrate that deep blue fluorescent emitter of L-BPPI can be a promising candidate for achieving highly efficient hybrid OLEDs with high quality white light.