Yang Xiaoting, Zhang Wenjing, Zeng Yicheng, Chong Yihuang, Liu Fangze, Wu Zhenghui, Shen Huaibin, Li Hongbo
School of Materials Science and Engineering, Beijing Institute of Technology, No. 5 Zhongguancun South Street, Haidian District, Beijing, 100081, P.R. China.
CAS Key Laboratory of Microscale Magnetic Resonance and School of Physical Sciences, University of Science and Technology of China, No. 96 Jinzhai Road, Hefei, Anhui, 230026, P.R. China.
Angew Chem Int Ed Engl. 2025 May 26;64(22):e202420421. doi: 10.1002/anie.202420421. Epub 2025 Apr 21.
Quantum-dot light-emitting diodes (QLEDs) are thought to be the base for next-generation display technology. However, the performance of blue-emitting QLEDs still falls behind those of green and red ones, which can be attributed to the energy loss from Auger recombination and the strong coupling of excitons with surface states. Blue quantum dots (QDs) with giant CdZnSeS alloy cores are expected to improve the internal confinement of excitons due to the nonmonotonical energy landscape of their conduction band, while they haven't shown high performance in QLEDs due to insufficient optimization of their shell structures. In this work, giant CdZnSeS alloy cores were synthesized by diffusing Zn atoms into CdSeS cores, so that the core/shell lattice stress was released due to the optimized gradient compositions. As a result, exciton transfer and Auger recombination are both suppressed, leading to a breakthrough external quantum efficiency (EQE) of 24% in blue QLEDs with giant CdZnSeS alloy cores. Compared to the more extensively studied blue quantum dots with CdSeZn alloy cores, blue QLEDs with giant CdZnSeS alloy cores also benefit from the suppressed Fermi level and nonmonotonical energy landscape of the conduction band minimum (CBM), which are crucial for confining the wavefunctions of the excitons. The improved exciton confinement explained the superior performances of giant CdZnSeS alloy cores over CdSeZn cores in blue QLEDs.
量子点发光二极管（QLED）被认为是下一代显示技术的基础。然而，蓝色发光QLED的性能仍落后于绿色和红色发光QLED，这可归因于俄歇复合导致的能量损失以及激子与表面态的强耦合。具有巨大CdZnSeS合金核的蓝色量子点（QD）由于其导带的非单调能量分布有望改善激子的内部限制，然而由于其壳层结构优化不足，它们在QLED中尚未表现出高性能。在这项工作中，通过将锌原子扩散到CdSeS核中来合成巨大的CdZnSeS合金核，从而由于优化的梯度组成释放了核/壳晶格应力。结果，激子转移和俄歇复合均受到抑制，使得具有巨大CdZnSeS合金核的蓝色QLED的外量子效率（EQE）达到24%，实现了突破。与研究更为广泛的具有CdSeZn合金核的蓝色量子点相比，具有巨大CdZnSeS合金核的蓝色QLED还受益于被抑制的费米能级和导带最小值（CBM）的非单调能量分布，这对于限制激子的波函数至关重要。激子限制的改善解释了在蓝色QLED中巨大的CdZnSeS合金核比CdSeZn核具有更优异的性能。
