Microemulsion Nanosized Zno Prepared Its Performance

Zinc oxide (ZnO) is an important direct wide band gap (3.37eV) semiconductor material. Compared with other wide gap semiconductor materials, like GaN, ZnO has many advantages such as higher exciton binding energy, better piezoelectric effect and lower growth temperature and so on. Therefore, It's expected that ZnO will play important roles in optoelectronic devices. The preparation of high quality nano structures is an important method to improve the photoelectric property of ZnO, and it has attracted considerable attention. Because of the two polar surfaces and multiple fast growth directions, ZnO can grow as various novel structures such as nanorods, nanowires, nanobelt, nanohelixes, and so on, in which good photoelectric property is detected.In our experiments, ZnO nano structures were prepared by precipitation and microemulsion method separately. The effects of different preparation conditions to the particle size and morphology are studied by DSC-TG, XRD, TEM and LGA. Than the effects of electric field is also investigated by introducing it to micro-emulsion. At last, we have done some works on the Photoluminescent properties of nano ZnO by studying its photoluminescence spectrum.It was found that the ZnO prepared by precipitation method was pure and well crystallized. The smallest particle size was 14.6nm, with narrow particle size distribution but the agglomeration was rather serious. While the ZnO prepared by microemulsion method was single crystal with a smallest particle size of 10.9nm and more narrow particle size distribution. We also found that different morphologies can be formed by microemulsion method. In our case, W/O resulted in nanosphere, while bicontinuous resulted in nanorods. whisker-like nano ZnO with diameter of l~3nm and length >70 was obtained by introducing electric field to microemulsion with anion/cation mixed surfactants. The reasonable mechanism we proposed to explain growth of ZnO nano whisker is as follow: first, the polarization of anion/cation mixed surfactants by electric field result in the formation of precursor of 1D ZnO nanowires, then the ZnO nanowires self-assembled to form whisker-like nano ZnO during calcination. photoluminescence spectrums obtained from nano ZnO with different particle size and aspect-ratio(L/D) showed that smaller particle size or L/D result in stronger visible light emission, while the whisker-like nano ZnO with higher crystallinity exhibited strong ultraviolet emission.