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. 2020 Dec 1;14(4):491–498. doi: 10.1007/s12200-020-1069-0

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

Weiguang Li 1,2,#, Jie Tang 1,2,#, Yanqiong Zheng 1,✉, Junbiao Peng 3, Jianhua Zhang 1, Bin Wei 1,✉, Xifeng Li 1
PMCID: PMC9743841  PMID: 36637756

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) rolloff. 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 Ω 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

Acknowledgements

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.

Footnotes

Weiguang Li obtained his bachelor’s degree from Changzhou University, China, in 2019. He is currently pursuing a master’s degree in Department of Microelectronics and Solid Electronics from School of Materials Science and Engineering, Shanghai University, China. His main research focus is on the structural design of organic light-emitting diodes used in solid lighting and display.

Jie Tang received his bachelor’ s degree from Nantong University, China in 2018, now he is a master degree candidate. He is focusing on the fabrication of highly efficient organic electroluminescent devices.

Yanqiong Zheng received her Ph.D. degree from Huazhong University of Science and Technology, China, in 2009, and then worked as a postdoc researcher in Kyushu Institute of Technology and Kyushu University, Japan, from 2009 to 2013. She started her current associate professor position in Shanghai University, China, in 2014. She has over 60 papers published in reputed international journals and several Chinese authorized patents. Her research field focuses on optoelectronic materials and devices. She is a member of the Chinese Chemical Society. She has undertaken some national and provincial projects.

Bin Wei received his B.Sc. degree in 1990 and M.Sc. degree in 1993 from Peking University, China, in 2002. He obtained his Ph.D. degree from University of Tsukuba, Japan. During the period from Oct. 1997 to Mar. 1998, he worked at University of Tsukuba as a special research fellow for Japanese Society for the Promotion of Science (JSPS). Since July 2007, he joined Key Laboratory of Advanced Display and System Applications of Shanghai University, China, direct for organic light-emitting semiconductor as a distinguished professor. Prof. Wei has focused on organic electroluminescent devices and organic lasing. He has published about 220 peer-reviewed articles in Nature Photonics, Nature Communication, Advanced Functional Materials, etc.

These authors contribute equally to this work.

Contributor Information

Yanqiong Zheng, Email: zhengyanqiong@shu.edu.cn.

Bin Wei, Email: bwei@shu.edu.cn.

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