Formation of ZnO/ZnCdSe Alloy Quantum Dots in the Presence of High Oleylamine Contents.

To the best of our knowledge, this report presents, for the first time, the schematic of the possible chemical reaction for a one-pot synthesis of ZnCdSe alloy quantum dots (QDs) in the presence of low/high oleylamine (OLA) contents. For high OLA contents, high-resolution transmission electron microscopy (HRTEM) results showed that the average size of ZnCdSe increases significantly from 4 to 9 nm with an increasing OLA content from 4 to 10 mL. First, [Zn(OAc)]-OLA complex can be formed by a reaction between Zn(OAc) and OLA. Then, Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) data confirmed that ZnO is formed by thermal decomposition of the [Zn(OAc)]-OLA complex. The results indicated that ZnO grew on the ZnCdSe surface, thus increasing the particle size. For low OLA contents, HRTEM images were used to estimate the average sizes of the ZnCdSe alloy QDs, which were approximately 8, 6, and 4 nm with OLA loadings of 0, 2, and 4 mL, respectively. We found that Zn(OAc) and OLA could form a [Zn(OAc)]-OLA complex, which inhibited the growth of the ZnCdSe alloy QDs, due to the decreasing reaction between Zn(oleic acid) and Se, which led to a decrease in particle size.