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Sidney Malak1 Marcus Smith1 2 Young Jun Yoon1 Chun Hao Lin1 Jaehan Jung1 Zhiqun Lin1 Vladimir Tsukruk1

1, Georgia Inst of Technology, Atlanta, Georgia, United States
2, Air Force Research Laboratory (AFRL), WPAFB, Ohio, United States

Engineering of the core-shell interface for QDs has been shown to be of significant importance, however a thorough investigation to better understand this interface has not been demonstrated. Here we analyze CdSe core, CdSe/ZnS core/shell, and CdSe/Cd1–xZnxSe1–ySy core/graded shell QDs to understand the effect of the interface on the resulting stability of the QD. Changes in the emission characteristics (spectral shift and intensity change) were observed, depending on the QD architecture and exposure conditions. Specifically, upon light exposure core QD show very low stability, core-shell QDs show decay to recovery behavior, occurring over seconds to minutes, and core-graded shell QDs exhibit enhanced stability in terms of photoluminescence. Studies suggest that the decay dynamics associated with the QDs are a result of the strong influence of the surrounding environment (i.e. oxygen, humidity, light, etc.). This work offers general guidelines to understanding and evaluating emission characteristics of stable and unstable QDs. Tunability of the photoluminescence behavior can have great application in situations where long device lifetimes are highly desirable (e.g., QD displays, LEDs, and lasers), or in the case of exploring dynamic properties for tunable emission patterning

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