Document Type

Journal Article


Department of Physics


Manipulation and exploitation of singlet and triplet excitons for hybrid white organic light-emitting diodes with superior efficiency/CRI/color stability




High performing tetra-chromatic hybrid white organic light-emitting diode (WOLED), with a fluorescent blue emitting layer (EML) of Bis[2-(2-hydroxyphenyl) -pyridine]beryllium (Bepp2) sandwiched between a pair of phosphors-doped hole transporting layer (HTL) and electron transporting layer (ETL), was developed. This was achieved by controlling the location of the green phosphor doped in HTL and yellow phosphor doped in ETL at ∼1 nm away from the HTL/EML and EML/ETL interfaces, and incorporating an ultrathin red phosphorescence layer (< 0.1 nm) in the center of Bepp2 EML. The resulting hybrid WOLED realizes good warm white emission, showing stable electroluminescence spectra with a maximum color rendering index (CRI) of 94 and a low correlated color temperature of 2440−2468 K over a wide voltage range from 5−9 V. Meanwhile, this WOLED also achieves high device efficiency, the maximum current efficiency, power efficiency, and external quantum efficiency up to 34.15 cd/A, 29.51 lm/W, and 17.71 %, respectively. Such high performance is realized through the precise manipulation and effective exploitation of singlet and triplet excitons via novel device design. Moreover, the proposed WOLED also removes the additional interlayers between the fluorescent and phosphorescent emitting regions that are commonly employed in the conventional hybrid WOLEDs, inducing a simplified device structure with reduced heterojunction interfaces, which is very beneficial for promoting the commercial development of WOLEDs.

Publication Date


Source Publication Title

Journal of Materials Chemistry C


Royal Society of Chemistry

Peer Reviewed



This work was financially supported by National Natural Scientific Foundation of China (Grant No. 61705156, 61605137); K. C. Wong Education Foundation–Hong Kong Baptist University (HKBU) Fellowship Program for Mainland Visiting Scholars 2017–2018; Key Innovative Research Team in Science and Technology of Shanxi Province (Grant No. 201513002-10); HKBU Inter-institutional Collaborative Research Scheme (ICRS) (Project No. RC-ICRS/15-16/04) and Shanxi Province Natural Science Foundation (Grant Nos. 201601D021018, 201601D011031).



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