Photoluminescence quenching of green synthesized manganese doped zinc oxide by sodium iodide doped Polypyrrole polymer

摘要

Nanocrystalline ZnO particles doped with Manganese(Mn) were prepared by a green synthesis method using cucum sativa fruit pulp extract as biosolvent. Different concentration of Mn(II) was incorporated in ZnO to study the dopant effect in ZnO. The X-ray diffraction pattern data shows a decrease in grain size for Mn-ZnO from 46 nm to 31 nm with the increase in Mn concentration. Scanning electron microscopy reveals spherical morphology with a decrease in particle size while increasing the dopant concentration. With an increase in Mn doping the band gap is observed to reduce from 3.14 eV to 3.01 eV which is due to band tailing effect. The luminescence of ZnO is quenched by increasing the dopant ions concentration which might be attributed to the quenching ability of Mn ions in the ZnO lattice. While 5% Mn doped ZnO (MZO) showed improved crystallinity, enhanced optical property and reduced particle size, we have chosen this concentration for thin film fabrication using Dip coating unit. At the same time, sodium iodide(NaI) doped Polypyrrole(PPy) powder synthesized by the chemical polymerization method exhibited a band gap of 2.57 eV. As the bandgap of NaI doped PPy falls in the higher range of visible region, it was taken further to make nanocomposite thin film by dip coating with 5% MZO nanoparticles. The photoluminescence intensity of the MZO-NaI PPy nanocomposite thin film got reduced drastically suggesting better electron-hole separation efficiency at the interface of MZO-NaI PPy nanocomposite thin film. Due to the improved electron-hole separation efficiency of the synthesized nanocomposite, it might find a possible application in the hybrid solar cell.