Photoluminescence properties of ZnS nanoparticles co-doped with Pb2+ and Cu2+

Nanometer-scale ZnS, ZnS:Cu, ZnS:Pb, and ZnS co-doped with Cu2+ and Pb2+ have been synthesized using a chemical precipitation method. X-ray diffraction analysis shows that the diameter of the particles is 2–4 nm. These nanocrystals can be doped with copper and lead during the synthesis without altering the X-ray diffraction pattern. However, doping has shifted the luminescence to 530 nm (Cu2+-doped) and 500–550 nm (co-doped with Cu2+ and Pb2+). In the case of ZnS:Pb nanocrystals, a relatively broad emission band (color range from blue to yellow) has been observed and its excitation wavelength shows a red shift. The photoluminescence intensity increases as the ZnS nanoparticles co-doped with Pb2+ and Cu2+. The results strongly suggest that doped ZnS nanocrystals, especially two kinds of metals activated ZnS nanocrystals, form a new class of luminescent materials.