Investigation of optical properties of sodium superoxide loaded polyaniline in uv and visible region

Abstract

The PANi/NaO2 composites were prepared using an ex-situ technique in 5–20 wt.% range. The NaO2 was prepared in a single step by heating sodium nitrate in oxygen rich environment. Ultraviolet-visible spectroscopy was employed to extract optical parameters like direct band gap, refractive index, complex dielectric constant and optical conductivity. The refractive index increased with NaO2 content for 5 and 10 wt. %, and then decreased possibly due to non-bridging oxygen (NBO) atoms. The composite with 10 wt. % NaO2 showed the largest refractive index. On increasing the concentration of NaO2, the band gap decreased from 2.538 to 2.307 eV and became narrower. Beyond 225 nm wavelength the extinction coefficient increased linearly, indicating that light trapping was proportional to wavelength. Both parts of the dielectrics follow the same pattern and the real dielectric constant is higher than the imaginary dielectric constant. The optical conductivity increased with h due to a change in density of localized states in the band gap, and also possibly due to the electrons excited by photon energy.

Keywords

• chemical synthesis
• sodium superoxide
• optical conductivity
• direct band gap
• dielectric constant