Hydrothermal and microwave fabrication of ZnO nanorods using ethanolic quantum dot precursors

ZnO is a promising material for composite photovoltaic solar cells due to the material's n-type character, wide band gap (3.2 eV), and favorable position of the conduction band relative to the excited states of interfacial light sensitizers. Visible light sensitizers may be organic dyes or inorganic semiconductors. ZnO nanorods were synthesized from base-modified ethanolic suspensions of ZnO quantum dots. The particles were coarsened using a conventional hydrothermal method or microwave treatment, each in high-pressure vessels. Microwave treatment allowed shorter reaction times than conventional thermal methods, and also resulted in nanorod morphologies. Powders of the ZnO nanorods were characterized by XRD, FTIR, SEM, thermal analysis, and nitrogen absorption. The rods were found to be highly asymmetric, with particle size and degree of asymmetry influenced by zinc and hydroxyl concentrations in the precursor suspensions. Porous films were deposited and analyzed on transparent conductive oxides to determine photocurrent onset potentials relative to SCE.