Semiconductor nanomaterials are much in demand for their technologically potential in various areas. At the same time, there is a compelling need to improve their synthetic reproducibility and particle yields at low reaction temperature. Accordingly, it is of critical importance to fill in the gap in our knowledge of the fundamental chemistry involved in conversion of nanocrystal (NC) precursors to nanocrystals (NCs). In this oral presentation, I will discuss our latest experimental and computational efforts towards such fundamental understanding. The Se exchange between tri-n-octylphosphine (P(C8H17)3 or TOP) and diphenylphosphine (HPPh2 or DPP), i.e. Se=P(C8H17)3 + HPPh2 = P(C8H17)3 + Se=PPh2H, has been acknowledged to be heavily weighted toward the left. With CdSe in 1-octadecene (ODE) (at ambient temperatures) as a model systems, the mechanism of conversion of the precursors in Reaction (1) at low temperature to CdSe NCs can be more rationally investigated by Reaction (3) than Reaction (2), the two reactions of which share a single conversion mechanism. We envision that our proposed mechanism, which should be generally applicable to ME semiconductor NCs, offers a practical mean to assist the design of low-temperature approaches to various binary ME and alloyed semiconductor nanomaterials.Cd(OOCC17H33)2 + Se=P(C8H17)3 + HPPh2= CdSe NCs (1)Cd(OOCC17H33)2 + Se=PPh2H =CdSe NCs (2)Cd(Se2PPh2)2 + Cd(OOCC17H33)2 + HPPh2= CdSe NCs (3)

Mechanism of conversion of precursors to binary semiconductor nanomaterials at low temperature

247th National Meeting (2014)

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