Synthesis and Analysis of Zinc Copper Indium Sulfide Quantum Dot Nanoparticles

Nanoparticle Zn[subscript 2x] Cu[subscript 1-x] In[subscript 1-x] S[subscript 2] is a promising and safer alternative to lead- and cadmium-containing quantum dots. Students prepare Zn[subscript 0.44] Cu[subscript 0.78] In[subscript 0.78] S[subscript 2] quantum dots in a one-pot synthesis without an inert atmosphere and investigate how the color, visible absorption band edge, and photoluminescence peak wavelength depend on the size of the particle. Octadecene is used as a noncoordinating solvent with a high boiling point. Oleic acid and stearic acid are used as ligands to dissolve the metal salts in the solvent at 150°C. Dodecanethiolate coordinates to the metal ion, and above 200°C, the metal thiolate decomposes to produce metal sulfide nanoparticles, coated in dodecanethiolate. Samples are withdrawn from the hot solution and quenched at room temperature to produce a series of increasing nanoparticle sizes with the same chemical composition.