The Preparation And Photoluminescence Of Polymer-ZnO Nano-composite Materials

Semiconductor nanocrystals have attracted much interest due to their unusual electrical and optical properties. As a wide band gap semiconductor material possesses large exiton binding energy of 60 meV at room temperature, ZnO is rationally expected to be promising candidates for room-temperature ultra-violet laser. While the correlation between the surface defects and visible luminescence of ZnO nanoparticles hinders the application in ultra-violet devices. In this thesis, electrospinning technique and microemulsion technique were applied to prepare polymer-ZnO nano-composite materials, and then realized the controllable UV luminescence of ZnO. The details are as following:1. Polyethylene oxide-ZnO (PEO-ZnO) nano-composite fibers were prepared by the combination of Sol-Gel method and electrospinning technique. The structural and optical properties of the products were investigated. Results indicated that the existence of a strong interaction between polyethylene oxide and ZnO nanoparticles, which passivated the interface defects of ZnO and quenched the visible emission of ZnO nanoparticles. This passivation effect of PEO could be enhanced by increasing the electrospinning voltages, and then the fibers exhibited more intense UV emission. The quantum confinement effect in thinner fibers was stronger, which was considered to be another reason for the enhancement of band-edge emission of ZnO.2. Polyvinylalcohol-zinc oxide (PVA-ZnO) nano-composite fibers were prepared by the combination of Sol-Gel method and electrospinning technique. The structural and spectral information of the nanofibers were characterized. The results indicated that ZnO were successfully embedded in the one-dimensional PVA fibers via chemical interactions between ZnO and PVA. Photoluminescence result showed the PVA/ZnO nanofibers had an intense white light emission, which originated from the simultaneous emission of three bands covering the whole visible and UV range. In terms of experimental results, a possible photoluminescence mechanism was...