Continuous Growth Synthesis of Zinc Oxide Nanocrystals with Tunable Size and Doping

Chemical syntheses of nanocrystals using colloidal techniques enable the production of a large variety of nanomaterials of desired size, shape, and composition. Therefore, these syntheses hold tremendous promise for the production of nanoparticles for next-generation technologies. However, they suffer from scalability issues, which can limit, or prevent, their translation into commercial technologies. Here, we show the synthesis of zinc oxide nanocrystals with controlled size and doping using a continuous growth method, which is easily scalable. We demonstrate the tunable growth of pure ZnO nanocrystals from ∼5 nm up to ∼30 nm, and the synthesis of plasmonic ZnO nanocrystals by incorporating substitutional trivalent dopants such as aluminum, gallium, and indium. We investigat the growth kinetics of these nanocrystals and used a variety of characterization techniques to fully elucidate the relationship between synthetic conditions and nanocrystal properties. We validate our reaction method by synthesizing Al-doped ZnO nanocrystals on a gram-scale and with a reaction yield of 100%. These nanocrystals are used to deposit thin coatings with excellent transparency and enhanced electrical conductivity compared to native ZnO.