摘要
Quantum dots (QDs) are advancing display and innovating lighting but still encountering unsolved stability problems mainly caused by material oxidation. In this work, the effect of Se composition (0.8 at. % vs 4.3 at. %) and thick ZnS shell (shell thickness ∼5 nm) on the oxidation of low-Cd content ZnS:(Cd,Se) QDs (Cd, <20 at. %) were investigated. Surface analysis and thermodynamic calculation were employed to study the QD oxidation. The results show that the oxidation products were correlated to (Zn,Cd)SO , (Zn,Cd)(OH) , and SeO phases, which lead to QD surface defects/amorphization inducing ligand detachment and particle agglomeration, indicating that the shell should be a much more dominant role in the QD reliability. It was also found that a heavier Se doping and thicker ZnS overcoating indeed prevented the oxidation of Cd, Zn, and S so the low-Cd QD stability could be improved. By considering the application criteria, optimized green QDs with diameter of ∼12 nm and chemical composition of Zn S :Cd Se are suggested for QD-based lighting and displays. A QD color enhancement film based on low-Cd QDs exhibited superior stability compared with a commercial product, demonstrating their potential in practical applications.