InP Quantum Dots (QDs) are being developed as an alternative to well-studied QDs that contain the heavy metal cadmium. While InP QDs offer size-tunable emission over the visible and near-infrared range and show reduced toxicity in comparison to CdSe, concerns exist about synthetically-induced broad size distributions, low photoluminescence (PL) quantum yields, and photostability. Shelling InP cores with ZnSe, a wide band gap material, has shown an increase in quantum yield up to 40% and a decrease in photodegradation. Further understanding the charge carrier dynamics of this material and correlating them to a change in structure allows for QDs to be developed for different applications. Ultrafast fluorescence upconversion spectroscopy provides valuable information about the QDs’ ensemble charge carrier and trapping dynamics immediately after excitation. The obtained femtosecond decay constants and relative amplitudes show the effectiveness of the surface passivation of the ZnSe shell and allow direct comparisons to what has been previously seen for CdSe. InP/ZnSe QDs were synthesized with an alloyed interface and compared to QDs with a core/shell structure. Using ultrafast fluorescence upconversion spectroscopy, shorter decay constants were found for InP/ZnSe QDs than other previously studied CdSe-based systems indicating more favorable trapping of charge carriers.<br/>

Ultrafast charge carrier dynamics of indium-alloyed thick-shell InP/ZnSe quantum dots

2019 Fall National Meeting

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