Influence of potassium permanganate on the anisotropic growth and enhanced UV emission of ZnO nanostructures using hydrothermal process for optoelectronic applications.

The effect of in situ addition of potassium permanganate (KMnO) in controlling morphology, composition, structural and optical properties of the ZnO nanostructures prepared by hydrothermal technique has been investigated. The influence of synthesis conditions on the growth of ZnO nanorods was meticulously studied by field-emission scanning electron microscope, X-ray diffractometer, transmission electron microscopy (TEM) and high-resolution TEM. It is demonstrated that the KMnO concentration has great influence on the morphology and on the alignment of ZnO nanorods. Further the optical properties of nanostructures were investigated by photoluminescence (PL) spectroscopy and ultraviolet-visible diffuse reflectance spectroscopy. The PL spectrum divulged a continuous suppression of defect-related broadband emission by increasing the concentration of the KMnO, which produced the quenching of surface defects present in the nanorods. The intensity ratio of the peaks corresponding to near-band emission (NBE) to that of deep-level emission of the KMnO-modified ZnO nanorods was found to increase by eightfold of magnitude. Further it must be noted that nearly 17-fold enhancement in the PL emission of the peak corresponding to NBE was observed in KMnO-modified ZnO compared to the ZnO grown without any additive. The I-V plot showed dependence of current values under dark and illumination over the amount of KMnO added during the growth stage. Graphical Abstract: [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]