Combination of post-growth treatments and their effects on ZnO microrods as potential UV phosphors

The effects of different post-growth treatments on the structural and optical properties of ZnO microrods are presented. Hexagonal ZnO microrods are initially synthesized by hydrothermal growth method and then coated with polyvinylpyrrolidone (PVP) and/or annealed in ambient air. The as-prepared and annealed microrods exhibit distinct hexagonal facets while the microrods subjected to PVP coating and to PVP coating with subsequent annealing have pitted surfaces. Moreover, the ZnO microrods with post-growth treatments have reduced and nearly suppressed visible emissions compared with the as-prepared microrods. The different post-growth treatments affect the morphology and photoluminescence properties but the average dimensions and crystallinity of the ZnO microrods are retained. Regardless of post-growth treatment, the ZnO microrods have intense and very fast UV emission with an average lifetime of less than 30 ps and therefore exhibit potential for UV phosphor applications.