Synthesis, characterization, and luminescent properties of ZnO–SiO2:PbS

Abstract

PbS and ZnO nanoparticles prepared separately by a sol-gel process were incorporated in SiO2 by an ex situ method, resulting in a green emitting ZnO–SiO2:PbS powder phosphor. Particle morphology, structure, and chemical composition of the ZnO nanoparticles, PbS nanoparticles, and ZnO–SiO2:PbS composite were analyzed with transmission electron microscopy, x-ray diffraction, and energy dispersive spectroscopy (EDS), respectively. With or without ZnO nanoparticles, green photoluminescence with a peak at 540nm was observed from SiO2:PbS when excited with a 325nm He–Cd laser in air at room temperature. This peak was different from defect-related emission from ZnO nanoparticles at 580nm and red-orange emission from SiO2:Pb2+ with a broad peak at 600–750nm. Again, the 540nm peak was different from the band edge emission from pure PbS nanoparticles at 1200nm. Note that this emission (540nm) was enhanced considerably when ZnO nanoparticles were incorporated. Photoluminescence properties of ZnO–SiO2:PbS is discussed.