Controlling Phase Conversion of Cu-Sb-Se Nanoparticles through the Use of an Amide Base

The family of copper antimony selenides is important for renewable energy applications. Several phases are accessible within narrow energy and compositional ranges, and tunability between phases is not well-established. Thus, this system provides a rich landscape to understand the phase transformations that occur in hot-injection nanoparticle syntheses. Rietveld refinements on X-ray diffraction patterns model anisotropic morphologies to obtain phase percentages. Reactions targeting the stoichiometry of CuSbSe₂ formed Cu₃SbSe₃ before decomposing to thermodynamically stable CuSbSe₂ over time. An amide base was added to balance cation reactivity and directly form CuSbSe₂. Interestingly, Cu₃SbSe₃ remained present but converted to CuSbSe₂ more rapidly. We propose that initial Cu₃SbSe₃ formation may be due to the selenium species not being reactive enough to balance the high reactivity of the copper complex. The unexpected effect of a base on cation reactivity in this system provides insight into the advantages and limitations for its use in other multivalent systems.