Selective synthesis of copper gallium sulfide (CuGaS2) nanostructures of different sizes, crystal phases, and morphologies

CuGaS2 nanostructures with different sizes, phases and morphologies were prepared. Chalcopyrite CuGaS2 nanocrystals with sizes ranging from 3.0 to 10.9 nm were synthesized using GaCl3, CuCl, and elemental sulfur as the precursors at temperatures ranging from 180 to 240 degrees C in hot-solvent synthesis. The CuGaS2 nanocrystals show size-dependent optical absorption and photoluminescence properties, exhibiting a quantum confinement effect. Wurtzite CuGaS2 nanostructures could be synthesized by replacing elemental sulfur with thiourea as the S source. We find that the amount of oleylamine (OLA) significantly affects the morphologies of the CuGaS2 nanostructures: CuGaS2 nanowires tend to form while the amount of OLA in the reaction decreased. The growth mechanism of CuGaS2 nanowires is proposed based on the experimental observation of morphology evolution from 130 to 240 degrees C.