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A Series of Dibenzofuran‐Based n‐Type Exciplex Host Partners Realizing High‐Efficiency and Stable Deep‐Red Phosphorescent OLEDs
Author(s) -
Ito Takashi,
Sasabe Hisahiro,
Nagai Yuji,
Watanabe Yuichiro,
Onuma Natsuki,
Kido Junji
Publication year - 2019
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201805907
Subject(s) - oled , phosphorescence , iridium , dibenzofuran , excimer , quantum efficiency , materials science , doping , optoelectronics , chemistry , photochemistry , fluorescence , optics , nanotechnology , physics , catalysis , organic chemistry , layer (electronics)
Deep‐red to near‐infrared (NIR) OLEDs, which yield emission peak wavelengths beyond λ =660 nm, are applicable as unique light sources in plant growth or health monitoring systems. Compared with other visible‐spectrum OLEDs, however, research in the field of deep‐red OLEDs is not as advanced. In this work, three new types of dibenzofuran‐based host materials are developed as n‐type exciplex host partners. Combining these with the deep‐red iridium complex bis(2,3‐diphenylquinoxaline)iridium(dipivaloylmethane) ([(DPQ) 2 Ir(dpm)]) and N , N ′‐di(naphalene‐1‐yl)‐ N , N ′‐diphenylbenzidine (α‐NPD) as a p‐type exciplex host partner, a highly efficient deep‐red OLED can be realized with a maximum external quantum efficiency ( η ext,max ) of over 16 % with Comission Internationale de l′Éclairge (CIE) coordinates of (0.71, 0.28). In addition, the effect of the doping concentration and the p / n ratio of the exciplex host on the efficiency and the lifetime of the OLEDs are investigated. Consequently, the optimized device exhibits a η ext,max of over 15 % and a six‐time longer lifetime operating at high brightness of 100 cd m −2 compared with other state‐of‐the‐art deep‐red OLEDs.