Kinetic studies on the formation of various II–VI semiconductor nanocrystals and synthesis of gradient alloy quantum dots emitting in the entire visible range

Abstract

From kinetic experiments monitoring the consumption of chalcogenide precursors by ³¹P NMR, it could be concluded that the formation rates of metal chalcogenides (M–E, M = Cd or Zn and E = Se or S) were in the order of ZnS < ZnSe < CdS < CdSe when one equivalent of metal oleate (M–OA) precursor reacted with one equivalent of trioctylphosphine chalcogenide (TOP–E) precursor. On the basis of the reactivity differences, various amounts of each precursor molecule could be deliberately chosen to tune the structure of the generated QDs and consequently the emission colors in the entire visible range. The excellent photochemical stability of the gradient alloy QDs could provide evidence that a good overall coverage of the shell on the core part significantly reduced defects due to lattice mismatch.