Influence factors and mechanism of emission of ZnS:Cu nanocrystals**Project supported by the National Natural Science Foundation of China (Grant Nos. 61205193, 61204065, and 61307045), the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20112216120005), and the Developing Project of Science and Technology of Jilin Province, China (Grant Nos. 201201116, 20140520107JH, and 20140204025GX).

Abstract

Copper-doped ZnS (ZnS:Cu) nanocrystals are synthesized by the sol–gel method. The average size of the ZnS:Cu nanocrystals is 3.1 nm. The x-ray diffraction indicates that increasing the Cu-dopant concentration results in a large shift in the diffraction angle. The effects of the dopant concentration, the reactant ratio, and aging temperature on the optical properties of the ZnS:Cu nanocrystals are also investigated. The fluorescence emission mechanism is analyzed by peak deconvolution using Gaussian functions. We find that the emission of the ZnS:Cu nanocrystal is composed of different luminescence centers at 430, 470, 490, 526, and 560 nm. The origins of these emissions are discussed and demonstrated by controlled experiments.