Controlled synthesis of wurtzite CuInS2 nanocrystals and their side-by-side nanorod assemblies

Wurtzite CuInS2 nanocrystals have been synthesized by direct reaction of copper nitrate, indium nitrate and dodecanethiol. The size and shape of the nanocrystals could be elaborately controlled by varying the Cu/In ratio and additional ligands other than dodecanethiol, such as oleylamine and oleic acid. Especially, the nanorods obtained under a Cu/In raw material ratio of 2 : 1 with the assistance of both dodecanethiol and oleic acid have good uniformity. They could further assemble into large-scale superlattices on substrates by solvent evaporation method. On the other hand, the optical property studies of the nanocrystals show that the band gap of wurtzite CuInS2 is 1.63 eV, which is optimal for solar cell applications. This report provides valuable insight into the controlled synthesis of ternary I-III-VI2 semiconductors and the assembly process, packing them into oriented films.