Optical and structural characterization of solution processed zinc oxide nanorods via hydrothermal method

Solution processing of zinc oxide (ZnO) is an effective and low-cost method for large surface area fabrication. This paper reports on the fabrication and properties of ZnO nanorods synthesized via a low-temperature hydrothermal process on the FTO (F-doped SnO2) substrate covered with a ZnO seed layer. These nanorods were characterized using field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), photoluminescence (PL) measurements, and UV–vis spectroscopy (UV–vis). The resulting nanorods exhibited vertical orientation and uniform distribution on the substrate with a hexagonal crystal structure. Morphological changes of these nanorods and their aspect ratios were systematically investigated as a function of the deposition time and precursor concentration. Both XRD and HRTEM results indicated that the ZnO nanorods preferentially grow along the (002) direction. The synthesized ZnO nanorods possessed a UV emission peak at approximately 387 nm and a relatively strong orange-red emission peak at around 625–675 nm. The optical transmission showed a high transparency of 85% and 70% for the seed layer and nanorods respectively.