Cadmium‐Doped Zinc Sulfide Shell as a Hole Injection Springboard for Red, Green, and Blue Quantum Dot Light‐Emitting Diodes. Issue 15 (3rd March 2022)

• Record Type: Journal Article
• Authors: Liu, Bochen; Guo, Yue; Su, Qiang; Zhan, Yunfeng; Chen, Zhao; Li, Yang; You, Baogui; Dong, Xiaonan; Chen, Shuming; Wong, Wai‐Yeung
• Is Part Of: Advanced science. Volume 9:Issue 15(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-03-03
• Subjects: balanced charge carriers -- efficient quantum dot light‐emitting diodes -- high photoluminescence quantum yields -- hole injection springboard -- outermost CdZnS shell; Science -- Periodicals; 505
• DOI: 10.1002/advs.202104488
• Languages: English
• ISSNs: 2198-3844

Abstract

Abstract: A new strategy is developed in which cadmium‐doped zinc sulfide (CdZnS) is used as the outermost shell to synthesize red, green, and blue (RGB) quantum dots (QDs) with the core/shell structures of CdZnSe/ZnSe/ZnS/CdZnS, CdZnSe/ZnSe/ZnSeS/CdZnS, and CdZnSe/ZnSeS/ZnS/CdZnS, respectively. Firstly, the inner ZnS and ZnSe shells confine the excitons inside the cores of QDs and provide a better lattice matching with respect to the outermost shell, which ensures high photoluminescence quantum yields of QDs. Secondly, the CdZnS shell affords its QDs with shallow valence bands (VBs). Therefore, the CdZnS shell could be used as a springboard, which decreases the energy barrier for hole injection from polymers to QDs to be below 1.0 eV. It makes the holes to be easily injected into the QD EMLs and enables a balanced recombination of charge carriers in quantum dot light‐emitting diodes (QLEDs). Thirdly, the RGB QLEDs made by these new QDs exhibit peak external quantum efficiencies (EQEs) of 20.2%, 19.2%, and 8.4%, respectively. In addition, the QLEDs exhibit unexpected luminance values at low applied voltages and therefore high power efficiencies. From these results, it is evident that CdZnS could act as an excellent shell and hole injection springboard to afford high performance QLEDs. Abstract : Red, green, and blue quantum dots (QDs) with the cadmium‐doped zinc sulfide (CdZnS) shell are synthesized. The CdZnS shell affords its QDs with high photoluminescence quantum yields and shallow valence bands, which could act as a hole injection springboard and is beneficial to the hole injection in QD based light‐emitting diodes.