Synthesis, optical properties, and superlattice structure of Cu(I)-doped CdS nanocrystals

High quality Cu(I)-doped CdS [CdS:Cu(I)] nanocrystals were synthesized by thermolysis of metal acetylacetonate complexes in n-dodecanethiol. The optical emission of the doped nanocrystals was observed to change from surface trap-dominant emission to Cu(I)-dominant emission with respect to the reaction time and the doping levels of Cu(I) ions in CdS particles. The maximum photoluminescence quantum yields of the CdS:Cu(I) nanocrystals could reach 15.8%. More interestingly, these doped nanocrystals could self-assemble into highly ordered superlattices depending on the doping levels of the Cu(I) ions. A possible explanation for the formation of the CdS:Cu(I) nanocrystal superlattices is dipole-dipole interactions between the adjacent nanocrystals. (C) 2010 American Institute of Physics. [doi:10.1063/1.3466664]