Improved stability of blue TADF organic electroluminescent diodes via OXD-7 based mixed host

Weiguang LI, Jie TANG, Yanqiong ZHENG, Junbiao PENG, Jianhua ZHANG, Bin WEI, Xifeng LI

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Front. Optoelectron. ›› 2021, Vol. 14 ›› Issue (4) : 491-498. DOI: 10.1007/s12200-020-1069-0
RESEARCH ARTICLE

Improved stability of blue TADF organic electroluminescent diodes via OXD-7 based mixed host

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Abstract

Thermally activated delayed fluorescence (TADF) organic light-emitting diodes (OLEDs) have been demonstrated in applications such as displays and solid-state lightings. However, weak stability and inefficient emission of blue TADF OLEDs are two key bottlenecks limiting the development of solution processable displays and white light sources. This work presents a solution-processed OLED using a blue-emitting TADF small molecule bis[4-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone (DMAC-DPS) as an emitter. We comparatively investigated the effects of single host poly(N-vinylcarbazole) (PVK) and a co-host of 60% PVK and 30% 2,2′-(1,3-phenylene)-bis[5-(4-tert-butylphenyl)-1,3,4-oxadiazole] (OXD-7) on the device performance (the last 10% is emitter DMAC-DPS). The co-host device shows lower turn-on voltage, similar maximum luminance, and much slower external quantum efficiency (EQE) roll-off. In other words, device stability improved by doping OXD-7 into PVK, and the device impedance simultaneously and significantly reduced from 8.6 × 103 to 4.2 × 103 W at 1000 Hz. Finally, the electroluminescent stability of the co-host device was significantly enhanced by adjusting the annealing temperature.

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Keywords

blue thermally activated delayed fluorescence organic light-emitting diode (TADF OLED) / 2,2′-(1,3-phenylene)-bis[5-(4-tert-butylphenyl)-1,3,4-oxadiazole] (OXD-7) / bis[4-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone (DMAC-DPS) / stability

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Weiguang LI, Jie TANG, Yanqiong ZHENG, Junbiao PENG, Jianhua ZHANG, Bin WEI, Xifeng LI. Improved stability of blue TADF organic electroluminescent diodes via OXD-7 based mixed host. Front. Optoelectron., 2021, 14(4): 491‒498 https://doi.org/10.1007/s12200-020-1069-0

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Acknowledgments

This work was financially supported by the National Key Research and Development Program of China (No. 2017YFB0404404), and the Open Fund of State Key Laboratory of Luminescent Materials and Devices (South China University of Technology), China.

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2020 Higher Education Press
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