Phase and Morphological Control of Copper(I) Chalcogenide Nanocrystals
Robinson, Evan Hojer
Nanocrystals retain many of the desirable characteristics of their bulk counterparts but offer advantages in ease of processing and property manipulation for end-of-line applications. The family of semiconductor nanocrystals discussed herein are the copper chalcogenides, which are known for having bandgaps suitable for solar-energy capturing, stoichiometry-dependent localized surface plasmon resonances, and for being parent materials to numerous ternary and quaternary semiconductor compounds. Copper(I) sulfide nanorods were synthesized using 1,2-hexadecanediol, which stabilized seed nanocrystals at the reaction temperature but did not impede dipole-induced oriented attachment. A direct synthesis was developed for a recently discovered hexagonal phase of copper(I) selenide, and this metastable phase was accessed through a less-reactive nanocrystal precursor, didodecyl diselenide. The thermodynamic phase was directly synthesized with the more-reactive dodecyl selenol, and in situ formation of a Cu-selenoate complex was found to be responsible for lowering the C-Se bond dissociation energy of the selenol. Copper telluride nanocrystals and nanosheets of the Vulcanite phase were synthesized using a ditelluride precursor analogous to the diselenide precursor, and represented the first time nanosheets of this material had been synthesized solvothermally. Additional work included investigation into phase control with other semiconductor nanocrystals using selenol and diselenide precursors, progress toward synthesis of monovalent copper sulfide nanoclusters, and charge transfer between cobalt complexes and fluorescent quantum dots.