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Highly Efficient and Air‐Stable Lanthanide Eu II Complex: New Emitter in Organic Light Emitting Diodes
Author(s) -
Zhan Ge,
Wang Liding,
Zhao Zifeng,
Fang Peiyu,
Bian Zuqiang,
Liu Zhiwei
Publication year - 2020
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.202008423
Subject(s) - europium , oled , lanthanide , quantum yield , photoluminescence , boron , quantum efficiency , common emitter , luminescence , materials science , photochemistry , phosphor , chemistry , optoelectronics , fluorescence , nanotechnology , physics , optics , ion , organic chemistry , layer (electronics)
Luminescent Eu II complexes with a characteristic 5d–4f transition have potential applications in many fields. However, their instability in ambient conditions impedes further exploration and application. Herein, we report two new Eu II complexes, bis[hydrotris(3‐trifluoromethylpyrazolyl)borate]europium(II) ( Eu‐1 ) and bis[hydrotris(3‐methylpyrazolyl)borate]europium(II) ( Eu‐2 ). Intriguingly, the blue emissive Eu‐1 showed high air stability arising from fluorine protection and close molecular packing, as maintaining a photoluminescence quantum yield (PLQY) of 91 % (initial 96 %) upon exposure to air over 2200 hours. While the orange emissive Eu‐2 showed a maximum luminance of 30620 cd m −2 , and a maximum external quantum efficiency (EQE) of 6.5 %, corresponding to an exciton utilization efficiency around 100 % in organic light‐emitting diodes (OLEDs). These results could inspire further research on stable and efficient Eu II complexes and their application in OLEDs.