Structural and photoluminescence study of Mn doped ZnO nanostructures assisted by PVP

The tuneable band gap properties of ZnO (II-VI semiconductor) make it an excellent host lattice phosphor for photonic and electroluminescent device applications. Here we report a simple and low-temperature chemical precipitation method (70 ?C) to tune both morphology and optical emission of ZnO nanostructures using polyvinylpyrrolidone (PVP) and Mn doping. The effect of PVP addition on the structure of chemically synthesized hexagonal ZnO and Mn doped ZnO nanostructures was investigated. The morphology of the samples highlights the formation of nanorods in the pure ZnO while needle-like structure was obtained in the sample containing 22.8wt.% of PVP. The optical and emission properties of the synthesized ZnO-based samples were also determined. The samples show semiconducting nature with a dual photoluminescence (PL) emission with distinct peaks observed at 411 and 563 nm. The morphology and PL emission showed tremendous change with the addition of 22.8wt.% of PVP. Furthermore, the effect of Mn doping to the PVP modified ZnO samples was investigated. The blue PL emission at 437 nm in the Mn doped ZnO samples is due to bothMn doping and defects. The observed yellow emission at 564-573 nm region is attributed to the existence of defects such as singly ionised oxygen vacancies. This observed dual-emission behaviour with semiconducting bandgap holds great promise for various optoelectronic applications. Due to their distinct morphology, these unique needle-like structures can have significant potential applications.