Previously reported syntheses of metal sulfide nanocrystals whose size is controlled by precursor conversion kinetics have relied almost exclusively on a library of substituted thioureas. In order to expand the range of accessible rate constants and nanocrystal sizes accessible for CdS synthesis, we extend this library to substituted thiocarbonates, thiocarbamates, and cyclic thiones. These precursors react with cadmium oleate at temperatures between 180-240°C to form CdS nanocrystals with remarkably sharp absorption and emission features. The precursor conversion kinetics span six orders of magnitude at a given set of reaction conditions with a trend as follows: k(3°-thioureas) ≥ k(2°-thiocarbamates) &gt; k(2°-thiocarbonates) &gt; k(4°-thioureas) ≥ k(3°-thiocarbamates) &gt; k(cyclic 4°-thioureas). We observed exceptionally narrow absorbance and emission linewidths for CdS nanocrystals formed using thiocarbamate and thiocarbonate precursors (96-132 meV, 17-19 nm FWHM), indicating that the precursor structure can influence the nanocrystal monodispersity as well as the conversion rate.

Beyond thioureas: Highly monodisperse CdS nanocrystal syntheses via thiocarbonates, thiocarbamates, and thioureas

253rd National Meeting (2017)

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