Growth And Mechansim Of ZnO Nanowire Arrays On Flexible Substrates Via Solution Methods

The orientation of nanomaterials could be rational controlled by forming ordered nanoarray structure. Furthermore, their sizes, dimensions, compositions, crystal structures and properties could also be well tuned to facilitate the applications in nanodevices. ZnO nanowire, with carbon nanotube and silicon nanowire are considered to be the most important nanomaterials in 21st, and have valuable applications in broadly fields including opticals, electrons, energy, sensor, biomedical, spintronics. Flexible devices are deemed to be the most potential device technology in next generation, due to the properties of flexible, portable, and have broken many traditional applications. Therefore, ordered nanoarrays directly grown on flexible substrates are crucial for the development of flexible devices. Currently, the ZnO nanoarrays are still mainly based on rigid substrates like Si wafer, ITO glass. Solution growth of ZnO nanoarray onto flexible substrates is the focus of recent researches. In this dissertation, ordered ZnO nanoarray based on flexible substrates grown by the solution method was researched, and the growth mechanism of ZnO nanoarrays on general substrates were explored. The results indicate that:1. ZnO nanowire arrays were successfully synthesized from electroplated Zinc layer on the flexible metal foil subtrates, by introducing electroplating technology, in Zn(NO3)2 and NH3 solution system. The distribution of ZnO nanowire arrays duplicates the surface morphology of the Zn plating layer. By varying the parameters of electroplating, the morphology of the Zn plating layer could be controlled, thus, the fabricating of patterned ZnO nanowire arrays in 3-dimensional are also can be achieved.2. The effects of different solution growth parameters like the amount of ammonia, reaction temperature, the concentration of Zn ion, were also investigated. The ratio aspect, density of the nanowire array can be tuned through the controlling of these growth parameters. By changing the amount of ammonia and reaction temperature, some other structure like ZnO flowerlike structure and nanoplate arrays were also obtained uniformly on the substrates.3. By investigating the photoluminescence properties, we found that the ZnO nanowire array, flower like structure, nanoplate arrays all have UV emissions. The growth method presented in this dissertation is applicable to large scale growth of ZnO nanowire arrays on flexible subtrates. It could be applied to fabricate flexible devices like flexible solar cells, sensors etc.4. The effects of different ligand, HMT, NH3, en, on the solution growth of ZnO nanowire arrays on general substrates were investigated. By measuring the interfacial tension between different ligand solutions and substrates, also taking the consideration of the effects of supersaturation degree, substrates on the nucleation, nuclei distribution, we found that by varying the concentration of the ligand in the solution, the interfacial tensions, the supersaturation degree, and the effects of substrates on nuclei distribution are all changed. Thus, the growth of ZnO nanowire arrays can be well controlled by varying the ligand concentration in the solution. We prepared ordered ZnO nanowire arrays on the ITO glass, Ni foil substrates by changing the ligands concentrations.