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Exciton‐Adjustable Interlayers for High Efficiency, Low Efficiency Roll‐Off, and Lifetime Improved Warm White Organic Light‐Emitting Diodes (WOLEDs) Based on a Delayed Fluorescence Assistant Host
Author(s) -
Wang Zhiheng,
Li XiangLong,
Ma Zerui,
Cai Xinyi,
Cai Chengsong,
Su ShiJian
Publication year - 2018
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201706922
Subject(s) - intersystem crossing , quantum efficiency , exciton , materials science , oled , optoelectronics , diode , electrical efficiency , quenching (fluorescence) , fluorescence , optics , layer (electronics) , nanotechnology , power (physics) , singlet state , physics , excited state , atomic physics , quantum mechanics
Recently, a new route to achieve 100% internal quantum efficiency white organic light‐emitting diodes (WOLEDs) is proposed by utilizing noble‐metal‐free thermally activated delayed fluorescence (TADF) emitters due to the radiative contributions of triplet excitons by effective reverse intersystem crossing. However, a systematic understanding of their reliability and internal degradation mechanisms is still deficient. Here, it demonstrates high performance and operational stable purely organic fluorescent WOLEDs consisting of a TADF assistant host via a strategic exciton management by multi‐interlayers. By introducing such interlayers, carrier recombination zone could be controlled to suppress the generally unavoidable quenching of long‐range triplet excitons, successfully achieving remarkable external quantum efficiency of 15.1%, maximum power efficiency of 48.9 lm W −1 , and extended LT50 lifetime (time to 50% of initial luminance of 1000 cd m −2 ) exceeding 2000 h. To this knowledge, this is the first pioneering work for realizing high efficiency, low efficiency roll‐off, and operational stable WOLEDs based on a TADF assistant host. The current findings also indicate that broadening the carrier recombination region in both interlayers and yellow emitting layer as well as restraining exciplex quenching at carrier blocking interface make significant roles on reduced efficiency roll‐off and enhanced operational lifetime.