Liu Xiaonan, Gao Yan, Li Bo, Yue Yansong, Wei Jing, Wu Zhenghui, Liu Fangze, Manna Liberato, Shen Huaibin, Li Hongbo
Beijing Key Laboratory of Construction Tailorable Advanced Functional Materials and Green Applications, Experimental Center of Advanced Materials, School of Materials Science and Engineering, Beijing Institute of Technology, Beijing, 100081, China.
Key Laboratory for Special Functional Materials of Ministry of Education, National & Local Joint Engineering Research Center for High-efficiency Display and Lighting Technology, Henan University, Kaifeng, 475004, China.
Adv Mater. 2025 Jul;37(29):e2504259. doi: 10.1002/adma.202504259. Epub 2025 May 15.
Quantum dot light-emitting diodes (QD-LEDs) hold great potential for enabling ultra-clear and ultra-bright display technologies. Although the operational life of QD-LEDs under static conditions has reached commercial standards, their dynamic stability, i.e., performance consistency while being switched on and off, remains largely behind that of state-of-the-art III-V inorganic LEDs. In this work, the degradation mechanism of red-emitting CdZnSe/ZnSe QD-LEDs with high external quantum efficiency (EQE) and long static operating lifetime is studied. Surprisingly, it is found that the accelerated EQE decline is mainly due to the fast-increasing electron leakage into the organic hole transport layer (HTL) under continuous voltage scans. To improve the dynamic stability of QD-LEDs, these findings inspired us to refine the size and architecture of CdZnSe/ZnSe QDs by introducing a ZnSeS/ZnS outer shell, where the ZnS shell improves the electron confinement and the ZnSeS mitigates the lattice mismatch between ZnSe and ZnS. Consequently, the electron leakage into the HTL is significantly inhibited, leading to QD-LEDs with minimal EQE drop of <4% after >5000 voltage cycles within a 0 - 4.5 V voltage range, while the devices still possessed excellent static stability, as their T at 1000 cd m for over 61 000 h.
量子点发光二极管（QD-LED）在实现超清晰、超亮显示技术方面具有巨大潜力。尽管QD-LED在静态条件下的使用寿命已达到商业标准，但其动态稳定性，即在开关状态下的性能一致性，仍远落后于最先进的III-V族无机LED。在这项工作中，研究了具有高外量子效率（EQE）和长静态工作寿命的红色发光CdZnSe/ZnSe QD-LED的退化机制。令人惊讶的是，发现加速的EQE下降主要是由于在连续电压扫描下电子快速泄漏到有机空穴传输层（HTL）中。为了提高QD-LED的动态稳定性，这些发现促使我们通过引入ZnSeS/ZnS外壳来优化CdZnSe/ZnSe量子点的尺寸和结构，其中ZnS外壳提高了电子限制，而ZnSeS减轻了ZnSe和ZnS之间的晶格失配。因此，电子向HTL的泄漏被显著抑制，导致QD-LED在0至4.5V电压范围内经过5000多次电压循环后EQE下降最小，<4%，而器件仍具有出色的静态稳定性，因为它们在1000cd m²下的T超过61000小时。
