Fluorinated dibenzo[a,c]-phenazine-based green to red thermally activated delayed fluorescent OLED emitters
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Purely organic thermally activated delayed fluorescence (TADF) emitting materials for organic light-emitting diodes (OLEDs) enable a facile method to modulate the emission color through judicious choice of donor and acceptor units. Amongst purely organic TADF emitters, the development of TADF molecules that emit at longer wavelengths and produce high-efficiency devices that show low efficiency roll-off remains a challenge. We report a modular synthesis route that delivers three structurally related fluorinated dibenzo[a,c]-phenazine-based TADF molecules, each bearing two donor moieties with different electron-donating strengths, namely 3,6-bis(3,6-di-tert-butyl-9H-carbazol-9-yl)-10-fluorodibenzo[a,c]phenazine (2DTCz-BP-F), 3,6-bis(9,9-dimethylacridin-10(9H)-yl)-10-fluorodibenzo[a,c]phenazine (2DMAC-BP-F) and 10,10'-(10-fluorodibenzo[a,c]phenazine-3,6-diyl)bis(10H-phenoxazine) (2PXZ-BP-F). They exhibit donor strength-controlled color-tuning over a wide color range from green to deep-red with photoluminescence maxima, λPL, of 505 nm, 589 nm, and 674 nm in toluene solution. OLED devices using these TADF materials showed excellent to moderate performance with an EQEmax of 21.8% in the case of 2DMAC-BP-F, 12.4% for 2PXZ-BP-F and 2.1% with 2DTCZ-BP-F, and associated electroluminescence (EL) emission maxima, λEL, of 585 nm, 605 nm and 518 nm in an mCBP host, respectively.
Hong , G , Si , C , Gupta , A K , Bizzarri , C , Nieger , M , Samuel , I D W , Zysman-Colman , E & Bräse , S 2021 , ' Fluorinated dibenzo[ a , c ]-phenazine-based green to red thermally activated delayed fluorescent OLED emitters ' , Journal of Materials Chemistry C , vol. Advance Articles . https://doi.org/10.1039/D1TC04918F
Journal of Materials Chemistry C
Copyright © 2021 The Author(s). Open Access. This article is licensed under a Creative Commons Attribution 3.0 Unported Licence.
DescriptionFunding: The authors would like to thank the RTG 2039 "Molecular Architectures for Fluorescent Cell Imaging" by the Deutsche Forschungsgemeinschaft (DFG) for financial support. C. S. thanks the China Scholarship Council (201806890001). We thank Dr. Tomas Matulaitis for help with DEST measurements. A. K. G. is grateful to the Royal Society for Newton International Fellowship NF171163. We acknowledge support from the UK's Engineering and Physical Sciences Research Council (grants EP/P010482/1 and EP/L017008/1). E. Z.-C. is a Royal Society Leverhulme Trust Senior Research fellow (SRF\R1\201089).
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