The physical properties of colloidal semiconductor quantum dots (QDs) are strongly coupled to the intended or unintended formation of intrinsic and extrinsic defect sites. To understand how extrinsic defects are formed during the growth of colloidal QDs we have started an effort using molecular analogs of II-VI QDs as model systems of the active surfaces of QDs. These molecular analogs are the well-known metal chalcogenide molecular clusters with the general formula [M4(EPh)10]2- and [M10E4(EPh)16]4- (M = Zn, Cd, Co, Mn and E = S, Se) and have long been used as single-source precursors for producing QDs and transition metal doped QDs. Our current studies deal with the metal exchange reactivity and electronic structures of extrinsic defects in these molecular clusters. We have confirmed incorporation of Co2+ into the [Cd4(SPh)10]2- and [Zn4(SPh)10]2- clusters at low temperature by 1H-NMR, EPR, high-resolution mass spectrometry, and variable-temperature variable-field magnetic circular dichroism spectroscopy. However, differences in the NMR spectra and MS data of the doped tetrameric clusters strongly suggests that the equilibrium constants for [Zn4�xCox(SPh)10]2� and [Cd4-xCox(SPh)10]2- are significantly different. Efforts to understand the stabilities and formation mechanism of these doped clusters as a function of temperature using in situ spectroscopic techniques are currently underway.

Incorporation of dopant ions in II-VI molecular clusters

247th National Meeting (2014)

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