Zno Nanocrystals, Nanorods And El Characteristics

The main objective of this dissertation is to study the key aspects of ZnO-based materials for fabrication of wide band-gap optoelectronic devices. The strategy directing these devices is similar, that is, to take advantage of the ultra-small stmctures physically confining the behavior of electrons in particular dimension for the realization of some unconventional and peculiar optical performance. Indeed, some interesting luminescence properties, such as amplified stimulated emission and lasing on the basis of given nanostructures, have already been investigated by some researchers. However, most above optical properties are investigated under the optical excitation, which hinders the further development into practical application by the difficulties associated with the complex apparatus, high expense, poor orientation and high power consumption. In contrast, electrically driven luminescence based on the well-designed nanostructures provides an alternative and intriguing strategy for the mechanism analysis and application exploration. Thus, for the ZnO-based materials, it is necessary to investigate the luminescence properties under the electrically excitation based on the well-fabricated nanostructures.In this study, we focused on the electroluminescence (EL) of different ZnO-based nanostructured materials. Firstly, mesoporous precursor was synthesized by a natural templating route, in which octadcylamine (ODA) and pluronic F-127 were respectively chosen as the template-directing reagents. Results from the nitrogen adsorption-desorption isotherms showed that mesoporous materials prepared with ODA and F-127 possess a narrow pore distribution of 3.84nm and 4.90nm, and a large surface area of 223m~2/g and 233m~2/g, respectively. The surfactants in the as-synthesized mesoporous zinc sulfide could be effectively removed by alcohol extraction and the mesoporous structure keep stable even after the surfactant was removed. The remaining surfactants played an important role of bridge in keeping the mesoporous structure. Besides, the method provided in this article is easily controllable, well-repeatable, mild and feasible to apply to the fabrication of mesoporous of other semiconductor materials.ZnO nanorods were synthesized by the refluxing method in the presence of DBS (Dodecyl benzene sulfonic acid sodiumsalt). Low temperature was introduced torestrain the growth of nanorods. ZnO nanorods obtained in this experiment were 80-100nm in diameter and ~2μm in length. It has been found that the parameters including the temperature, surfactant, ultrasonic and refluxing time played important role in formatting ZnO nanorods. Compared with other methods, that used ultrasonic and low temperature conditions was key to form uniform ZnO nanorods with smaller diameter.The electroluminescence (EL) spectra of the ZnO nanocrystallite annealed from various ZnS precursors have been investigated. Green emission with a band at around 510nm was obtained for the first time and interestingly, the emission intensity could be markedly enhanced when the samples were annealed from the mesoporous precursors. The emission intensity of samples annealed from the precursor dealt with ODA and F-127 were about 1.5 times and 6.5 times higher than that of the sample dealt with no surfactants, respectively. Mesoporous structure of precursors was regarded as being responsible for the marked enhancement of the luminescence intensity. The EL intensity keeps stable under the unchanged voltage and can repeated in the measurement time.Furthermore, we have also investigated the EL property of ZnO nanorods prepared in the former experiment. In contrast to the EL spectra gathered from nanocrystallite ZnO, the emission band red-shifted to the position around 730nm. Besides, the intensity of EL emission has markedly decreased in contrast to the value of nanocrystallite sample. It is likely that the shape and particle state of ZnO sample have great influence on the luminescence property. The above-mentioned two results may mainly came from the anisotropism of the ZnO nano...