Synthesis, characterization, and luminescent properties of ZnO-Si O ₂:PbS

PbS and ZnO nanoparticles prepared separately by a sol-gel process were incorporated in Si O ₂ by an ex situ method, resulting in a green emitting ZnO-Si O ₂:PbS powder phosphor. Particle morphology, structure, and chemical composition of the ZnO nanoparticles, PbS nanoparticles, and ZnO-Si O ₂: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 540 nm was observed from Si O ₂:PbS when excited with a 325 nm He-Cd laser in air at room temperature. This peak was different from defect-related emission from ZnO nanoparticles at 580 nm and red-orange emission from Si O ₂: Pb2+ with a broad peak at 600-750 nm. Again, the 540 nm peak was different from the band edge emission from pure PbS nanoparticles at 1200 nm. Note that this emission (540 nm) was enhanced considerably when ZnO nanoparticles were incorporated. Photoluminescence properties of ZnO-Si O ₂:PbS is discussed.