Preparation, Photoluminescence Of ZnO Nanoparticles And Their Thin Films

Recent progress in the synthesis and characterization of Quantum-sized ZnO shows that it is a very interesting material that can be used in photoelectric conversion, photocatalysis, sensing device and panel display. ZnO, an important luminescent material, has been attracting more attentions in small-sized range. It is significant to study the photoluminescence (PL) of Quantum-sized ZnO colloids, nanoparticles and thin films.An overview of the preparation and photoluminescence properties of ZnO colloids, powders with different morphology and thin films was presented. Quantum-size 2-propanol ZnO colloids, hydrosol and powders/thin films were prepared by sol technology, and were characterized by XRD, TEM, XPS, IR, UV-Vis, TG, AFM and laser granulometry methods. XRD and TEM observation coupled with the selected area electron diffraction revealed that the as-prepared ZnO particles crystallized in the wurtize phase with the particle size of 5.5 - 7.5 nm, and exhibited the preferential growth in the (002) direction in some extent. IR studies identified only the acetic acid and water molecules that were adsorbed on the surface of zinc oxide nanoparticles. The effects of exciting light, heat treatment temperatures on the photoluminescence, polarized PL properties of ZnO powder/thin film were investigated. It was found that the luminescence spectra of ZnO could be optimized by simply varying the exciting light and heat-treatment temperatures. Blue emission (463 nm) was obtained when the ZnO was heated under 300 癈 and the vertical-polarized exciting light (310 nm) was used. Polarization-sensitive measurements revealed an obvious anisotropy in the PL spectra of the wurtize ZnO nanoparticles. The polarization ratio, p = 0.87, was obtained in this case. The composite film of zinc oxide and copper phthalocyanine (CuPcRn) was prepared by modifying the surface of zinc oxide thin films with CuPcRn. It was found that the adsorption of CuPcRn onto the surface of ZnO could strongly affect the PL properties of nanosized ZnO thin film. The composite films exhibited a polarization ratio of 0.89 at 426 nm in the PL spectrum, with the vertical polarization of the exciting light (310 nm).