Determination of particle size distribution of water-soluble CdTe quantum dots by optical spectroscopy

Abstract

In the present study, we report the synthesis of glutathione (GSH) capped CdTe quantum dots (QDs) using the one-pot approach as well as their optical properties. These QDs were used as a probe for a detailed quantitative correlation between spectroscopic data and QDs size dispersion. We have developed a spectroscopic method to determine the size dispersion of QDs in solution based on the fluorescence spectroscopy and the fluorescence quantum yields. Our results demonstrate that the one-pot approach produces GSH-capped CdTe QDs of narrow size dispersion, as inferred by the sharp line width (full width at half maximum) of the fluorescence signal (from 153 meV to 163 meV), as revealed by our spectroscopy method. We observed that the GSH-capped CdTe QDs cause an increase in fluorescence quantum yield from 11% to 30% concomitantly with an increase in lifetime decay from 38 to 50 ns during the course of synthesis (from 15 min to 120 min), indicating an increase in the average size of the QDs. Finally, we have used the evolving factor analysis together with the multivariate curve resolution-alternating least squares method to corroborate our results, and we found a good agreement between both methods with the advantage that in our method, we were able to obtain size dispersion rather than just the mean QD size.