Ternary Acceptor-Donor-Acceptor Asymmetrical Phenanthroimidazole Molecule for Highly Efficient Near Ultraviolet Electroluminescence with EQE > 4

We synthesized a novel ternary acceptor (A)-donor (D)-acceptor (A) asymmetrically twisted deep-blue emitting molecule, PPI-2BI, by attaching two electrophilic benzimidazole (BI) units to the C2 and N1 positions of a phenanthroimidazole (PI) donor unit. Profiting from the enhanced D-A electronic coup...

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Bibliographic Details
Published in:Chemistry : a European journal 2018-08
Main Authors: Liu, Bin, Zhu, Ze-Lin, Zhao, Jue-Wen, He, Dan, Wang, Zhong-Yi, Luo, Chen-Yuan, Tong, Qing-Xiao, Lee, Chun-Sing, Tao, Si-Lu
Format: Article
Language:English
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Summary:We synthesized a novel ternary acceptor (A)-donor (D)-acceptor (A) asymmetrically twisted deep-blue emitting molecule, PPI-2BI, by attaching two electrophilic benzimidazole (BI) units to the C2 and N1 positions of a phenanthroimidazole (PI) donor unit. Profiting from the enhanced D-A electronic coupling, electron injecting and transporting abilities of the new triangle-shaped A-D-A molecule are considerably improved and the molecule shows high photoluminescence (PL) and Electroluminescence (EL) efficiencies. Using PPI-2BI as a non-doped emitting layer (EML), an organic light-emitting device exhibits emission with color coordinates of (0.158, 0.124) and a maximum external quantum efficiency (EQE), current efficiency (CE) and power efficiency (PE) of 4.63%, 4.98 cd/A and 4.82 lm/W, respectively. Additionally, a simple bi-layer device using PPI-2BI as both the EML and the electron-transporting layer (ETL) also shows an EQE of 3.81% with little changes in color purity. Remarkably, a PPI-2BI-based doped device emits efficient near ultraviolet EL with color coordinates of (0.154, 0.047) and an EQE of 4.12%, which is comparable to that of the best reported near UV emitting devices.
ISSN:1521-3765