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

doi:10.1007/s12200-020-1069-0

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

Front Optoelectron. 2021 Dec;14(4):491-498. doi: 10.1007/s12200-020-1069-0. Epub 2020 Dec 1.

Authors

Weiguang Li^#^{1

2}, Jie Tang^#^{1

2}, Yanqiong Zheng³, Junbiao Peng⁴, Jianhua Zhang¹, Bin Wei⁵, Xifeng Li¹

Affiliations

¹ Key Laboratory of Advanced Display and System Applications of Ministry of Education, School of Mechatronic Engineering and Automation, Shanghai University, Shanghai, 200072, China.
² School of Materials Science and Engineering, Shanghai University, Shanghai, 200072, China.
³ Key Laboratory of Advanced Display and System Applications of Ministry of Education, School of Mechatronic Engineering and Automation, Shanghai University, Shanghai, 200072, China. zhengyanqiong@shu.edu.cn.
⁴ State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou, 510640, China.
⁵ Key Laboratory of Advanced Display and System Applications of Ministry of Education, School of Mechatronic Engineering and Automation, Shanghai University, Shanghai, 200072, China. bwei@shu.edu.cn.

^# Contributed equally.

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.

Keywords: 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); blue thermally activated delayed fluorescence organic light-emitting diode (TADF OLED); stability.