Highly efficient cuprous complexes with thermally activated delayed fluorescence and simplified solution process OLEDs using the ligand as host

Two strongly luminescent complexes, [Cu(czpzpy)(PPh 3 )]BF 4 ( 1 ) and [Cu(czpzpy)(POP)]BF 4 ( 2 ), bearing a new carbazole-based diimine ligand (czpzpy = 2-(9 H -carbazolyl)-6-(1 H -pyrazolyl)pyridine, PPh 3 = triphenylphosphine, and POP = bis[2-(diphenylphosphine)phenyl]ether) were synthesized and...

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Bibliographic Details
Published in:Journal of materials chemistry. C, Materials for optical and electronic devices Materials for optical and electronic devices, 2015-01, Vol.3 (6), p.1187-1195
Main Authors: Chen, Xu-Lin, Lin, Chen-Sheng, Wu, Xiao-Yuan, Yu, Rongming, Teng, Teng, Zhang, Qi-Kai, Zhang, Qing, Yang, Wen-Bing, Lu, Can-Zhong
Format: Article
Language:English
Subjects:
Activated
Carbazoles
Current efficiency
Emissivity
Emittance
Fluorescence
LIGANDS
PURIFICATION
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Summary:Two strongly luminescent complexes, [Cu(czpzpy)(PPh 3 )]BF 4 ( 1 ) and [Cu(czpzpy)(POP)]BF 4 ( 2 ), bearing a new carbazole-based diimine ligand (czpzpy = 2-(9 H -carbazolyl)-6-(1 H -pyrazolyl)pyridine, PPh 3 = triphenylphosphine, and POP = bis[2-(diphenylphosphine)phenyl]ether) were synthesized and characterized. Complex 2 emits intense thermally activated delayed fluorescence (TADF) with high photoluminescence quantum yields (PLQYs) of up to 0.98 at room temperature in the solid state. A highly efficient solution-processed OLED, with an emissive layer was spin-coated using a mixture of the diimine ligand czpzpy and the starting material, [Cu(CH 3 CN) 2 )(POP)]BF 4 , was fabricated with peak efficiencies of 6.36% (external quantum efficiency, EQE) and 17.53 cd A −1 (current efficiency, CE) and a maximum brightness of 3251 cd m −2 . These performances are nearly identical to those of the device whose emissive layer was comprised of complex 2 and czpzpy, indicating that this simplified process, which omits the preparation and purification of the emissive complex, is practicable in preparing efficient solution-processed OLEDs. In this approach, czpzpy, which bears a carbazole unit, was used both as a ligand to form the emissive cuprous complex and as a host matrix for the formed emitter.
ISSN:2050-7526
2050-7534
DOI:10.1039/C4TC02255F