Nearly monodisperse Cu-In-S ternary nanocrystals with tunable composition, crystalline structure, and size were synthesized by a hot-injection method using mixed generic precursors. Such ternary nanocrystals with zincblende and wurtzite structure were reported for the first time. This work correlates the crystalline structure of the binary ZnS nanoparticles with those of ternary Cu-In-S nanocrystals, demonstrating the feasibility of making their alloyed or core/shell structure. Furthermore, this work may provide suitable material candidates for low-cost, high-efficiency solar cell fabrication.

During our effort to synthesize the tetrahedral Au20 cluster, we found a facile synthetic route to prepare monodisperse suspensions of ultrasmall Au clusters AuN (N < 12) using diphosphine ligands. In our monophasic and single-pot synthesis, a Au precursor ClAu(I)PPh3 (Ph = phenyl) and a bidentate phosphine ligand P(Ph)2(CH2)(M)P(Ph)2 are dissolved in an organic solvent. Au(I) is reduced slowly by a borane-tert-butylamine complex to form Au clusters coordinated by the diphosphine ligand. The Au clusters are characterized by both high-resolution mass spectrometry and UV-vis absorption spectroscopy. We found that the mean cluster size obtained depends on the chain length M of the ligand. In particular, a single monodispersed Au11 cluster is obtained with the P(Ph)2(CH2)3P(Ph)2 ligand, whereas P(Ph)2(CH2)(M)P(Ph)2 ligands with M = 5 and 6 yield Au10 and Au8 clusters. The simplicity of our synthetic method makes it suitable for large-scale production of nearly monodisperse ultrasmall Au clusters. It is suggested that diphosphines provide a set of flexible ligands to allow size-controlled synthesis of Au nanoparticles.