Large-Scale Synthesis of InPZnS Alloy Quantum Dots with Dodecanethiol as a Composition Controller

A method for the large-scale synthesis of InPZnS alloy QDs was developed, which tune the optical properties by controlling the dodecanethiol to palmitic acid ratio. The control of the surfactant ratio resulted in the change of alloy composition. The absorption and emission peaks showed a blue shift as the amount of DDT increased, which implied the increase of ZnS contents. The alloy structure was confirmed with TEM, elemental analysis, XRD, and XPS; particularly, P-2p peaks for In-P and InP-S bonds in XPS analysis could give clear evidence. The alloy QDs were overcoated with a ZnS shell, and the quantum yields (QYs) were in the range of 20-45% for all wavelengths. Finally, a cadmium-free QD yield in a single reaction was determined to be 2.74 g.