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Publication - Dr David Benito-Alifonso

    Rapid phosphine-free synthesis of CdSe quantum dots

    promoting the generation of Se precursors using a radical initiator

    Citation

    Hou, B, Benito-Alifonso, D, Webster, R, Cherns, D, Galan, MC & Fermin, DJ, 2014, ‘Rapid phosphine-free synthesis of CdSe quantum dots: promoting the generation of Se precursors using a radical initiator’. Journal of Materials Chemistry A, vol 2., pp. 6879-6886

    Abstract

    The replacement of phosphine containing compounds in the synthesis of II–VI quantum dots (QDs) via
    the ‘hot-injection’ method has received considerable attention in
    recent years, in particular toward scaling-up production. A key
    bottleneck in current approaches is the poor solubility of elemental Se
    in solvents such as 1-octadecene (1-ODE) or oleylamine requiring a
    heating temperature of 200 °C for several hours, or the introduction of
    additives such as alkylthiols or NaBH4, or replacement by SeO2.
    In the present work, we elucidate the fundamental steps in the
    dissolution of elemental Se in 1-ODE and oleylamine with the view of
    facilitating the large-scale synthesis of CdSe QDs. The main
    organoselenium species generated during the solubilisation of elemental
    Se in 1-ODE and oleylamine were identified by 1D and 2D NMR spectroscopy
    (1H, 13C and 77Se). Experimental evidence suggests that the rate determining step is the formation of Se radicals, via
    homolytic cleavage of the Se–Se bond, that attack the allylic proton in
    1-ODE and oleylamine. Plausible reaction pathways in both systems are
    proposed. Finally, we demonstrate that the radical-mediated
    solubilisation of Se can be significantly accelerated by the addition of
    azobisisobutyronitrile (AIBN), a common radical initiator used in the
    polymer industry. In this way, a highly concentrated Se precursor was
    prepared. The “hot-injection” of the Se precursor into CdO containing
    1-ODE solution leads to the formation of highly luminescent CdSe QDs
    with a well-defined cubic structure.

    Full details in the University publications repository