Reduced efficiency roll-off in all-phosphorescent white organic light-emitting diodes with an external quantum efficiency of over 20%

Liping Zhu, Zhongbin Wu, Jiangshan Chen, Dongge Ma

Research output: Contribution to journalArticlepeer-review

64 Scopus citations

Abstract

Although previously reported all-phosphorescent white organic light-emitting diodes (WOLEDs) exhibit impressive electroluminescence efficiencies, problems remain in terms of the severe efficiency roll-off at high brightness. Here, a smart design of the emissive zone structure is presented to make full use of generated excitons to realize high efficiency all-phosphorescent WOLEDs with reduced efficiency roll-off. The fabricated WOLED shows a maximum power efficiency (PE) of 46.6 lm W-1, a current efficiency (CE) of 46.4 cd A-1 and an external quantum efficiency (EQE) of 22.4%. These values remain as high as 41.3 lm W-1, 46.2 cd A-1 and 22.0%, respectively, at a brightness of 1000 cd m-2, exhibiting less pronounced efficiency roll-off. The critical current density, where the EQE declines by half from its peak, reaches 220 mA cm-2, which should be a high value for all-phosphorescent WOLEDs with an external quantum efficiency of over 20%.

Original languageEnglish
Pages (from-to)3304-3310
Number of pages7
JournalJournal of Materials Chemistry C
Volume3
Issue number14
DOIs
StatePublished - 14 Apr 2015
Externally publishedYes

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