Blue light-emitting diodes based on colloidal quantum dots with reduced surface-bulk coupling

• Published in: Nature communications 2023-01, Vol.14 (1), p.284-284, Article 284
• Main Authors: Chen, Xingtong, Lin, Xiongfeng, Zhou, Likuan, Sun, Xiaojuan, Li, Rui, Chen, Mengyu, Yang, Yixing, Hou, Wenjun, Wu, Longjia, Cao, Weiran, Zhang, Xin, Yan, Xiaolin, Chen, Song
• Format: Article
• Language: English
• Subjects: 639/301/1005/1007; 639/301/357/1017; 639/624/1020/1089; Charge efficiency; Charge injection; Coupling; Degradation; Electroluminescence; Emissions; Energy levels; Humanities and Social Sciences; Injection; Light emitting diodes; multidisciplinary; Photoluminescence; Photons; Quantum dots; Quantum efficiency; Science; Science (multidisciplinary); Shells (structural forms)
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-023-35954-x

To industrialize printed full-color displays based on quantum-dot light-emitting diodes, one must explore the degradation mechanism and improve the operational stability of blue electroluminescence. Here, we report that although state-of-the-art blue quantum dots, with monotonically-graded core/shell/shell structures, feature near-unity photoluminescence quantum efficiency and efficient charge injection, the significant surface-bulk coupling at the quantum-dot level, revealed by the abnormal dipolar excited state, magnifies the impact of surface localized charges and limits operational lifetimes. Inspired by this, we propose blue quantum dots with a large core and an intermediate shell featuring nonmonotonically-graded energy levels. This strategy significantly reduces surface-bulk coupling and tunes emission wavelength without compromising charge injection. Using these quantum dots, we fabricate bottom-emitting devices with emission colors varying from near-Rec.2020-standard blue to sky blue. At an initial luminance of 1000 cd m −2 , these devices exhibit T 95 operational lifetimes ranging from 75 to 227 h, significantly surpassing the existing records. The surface localized charges in colloidal quantum dots induce a degradation that limits the electroluminescence performance. Here, Chen et al. propose quantum dots with monmonotonically-graded core/shell/shell structures to boost the device’s performance by reducing the surface-bulk coupling.