Influence of MnO2 nanoparticles on the optical properties of polypyrrole matrix

Abstract

Nanostructured polypyrrole (PPY), manganese dioxide (MnO2), and PPY-MnO2 nanocomposite were prepared by in-situ polymerization mechanism with varying concentrations of MnO2. Structural, morphological, and optical properties of synthesized nanocomposites were investigated by X-ray Diffraction (XRD), Field-Emission Scanning Electron Microscopy (FE-SEM), Transmission Electron Microscopy (TEM), and Ultraviolet and Visible (UV-VIS) techniques. The average crystallite size of nanocomposites was in 26–28 nm range. FE-SEM images depicted the presence of MnO2 nanospheres inside the globular morphology of PPY. TEM nano-graph proves homogenous mixing of MnO2 nanoparticles in PPY matrix. X-ray photoelectron spectroscopy (XPS) confirms the presence of elements (C, N, O, Mn) and their chemical state in the nanocomposite. The optical band gap and refractive index of optimized nanocomposite (20% PM) were calculated to be 1.53 eV and 2.49 respectively. The photoluminescence spectra of the nanocomposite revealed three bands attributed to violet, blue, and green bands. Color purity and decay time were calculated as 49.6% and 5.72 μs for 20% PM nanocomposite. Moreover, the nanocomposite exhibited a high electron-hole recombination rate, high optical conductivity, and optimized optical band gap demonstrated that it could be used in optoelectronic devices.