Hole-Injection-Barrier Effect on the Degradation of Blue Quantum-Dot Light-Emitting Diodes
Xiaojuan Sun1, Xingtong Chen1, Xinrui Li1, Jiachen Xie1, Xiongfeng Lin2, Qi Shen1, Longjia Wu2, and Song Chen1,3*（陈崧）
1 Suzhou Key Laboratory of Novel Semiconductor Optoelectronics Materials and Devices, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123 Jiangsu, China
2 TCL Corporate Research, Shenzhen 518067 Guangdong, China
3 Jiangsu Key Laboratory of Advanced Negative Carbon Technologies, Soochow University, Suzhou 215123 Jiangsu, China
ACS Nano 2024, 18, 7, 5898–5906
Abstract: Inefficient hole injection presents a major challenge in achieving stable and commercially viable solution-processed blue electroluminescent devices. Here, we conduct an in-depth study on quantum-dot light-emitting diodes (QLEDs) to understand how the energy levels of common electrodes and hole-transporting layers (HTL) affect device degradation. Our experimental findings reveal a design rule that may seem nonintuitive: combining an electrode and HTL with matched energy levels is most effective in preventing voltage rise and irreversible luminance decay, even though it causes a significant energy offset between the HTL and emissive quantum dots. Using an iterative electrostatic model, we discover that the positive outcomes, including a T95 lifetime of 109 h (luminance = 1000 nits, CIE-y = 0.087), are due to the enhanced p-type doping in the HTL rather than the assumed reduction in barrier heights. Furthermore, our modified hole injection dynamics theory, which considers distributed density-of-states, shows that the increased HTL/quantum-dot energy offset is not a primary concern because the effective barrier height is significantly lower than conventionally assumed. Following this design rule, we expect device stability to be enhanced considerably.
链接：//pubs.acs.org/doi/10.1021/acsnano.3c12840
