Bicone nanoflower evolution and multi-peak emission of polymer caped Cu doped ZnO.

A low-temperature polymer-assisted wet chemical method was used to synthesise Cu-doped ZnO bicone nanoflowers at three different polyethylene glycol (PEG) concentrations. The effects of PEG concentration on the structural, morphological and optical properties of Cu doped ZnO nanostructures were studied. X-ray diffraction studies revealed that the as-synthesized Cu doped ZnO nanostructures are highly crystalline with a hexagonal wurtzite phase. The scanning electron microscopy analysis showed that the prepared nanostructures have bicone- nanoflower morphology and PEG concentration has strongly influenced the size as well the shape of nanoflowers. The TEM analysis confirmed the nanoflower morphology and the presence of diffraction planes obtained from the XRD data. The compositional analysis was performed by x-ray photoelectron Spectroscopy. The surface passivation effect of PEG on the band gap energies was studied by analysing UV -visible spectra of all the samples. The room-temperature fluorescent spectra of all the nanoflowers showed multiple peak emissions, both in the ultra-violet and visible regions, with varying intensities. These recasted multiple peaks are attributed to the morphological modification caused by the PEG addition.