Structure and optical properties of nanocomposites based on polystyrene (PS) and calcium titanate (CaTiO3) perovskite nanoparticles

Abstract

Polystyrene (PS) thin films containing 4% and 8% calcium titanate (CaTiO3) perovskite nanofiller were prepared by film casting techniques. The influence of CaTiO3 loading on the structure and optical characteristic of PS were studied by using X-ray diffraction and UV-absorption spectroscopy. The XRD analysis showed the addition of CaTiO3 into PS enhanced the formation of crystal structure and resulted in the formation of nano-crystal with a smaller diameter. The optical characterizations showed that the addition of CaTiO3 reduced the transmission and increased the reflection of PS films for UV and visible wavelength of the incident light. Absorption of pure PS films was limited to less than 270 nm, while the absorption of PS/CaTiO3 composites film covered the whole UV -range. The values of the optical energy gap were calculated by using Tauc equation. It was found that the addition of 8% CaTiO3 decreased the values of optical energy gaps from 4.42 eV to 4.26 eV. This is suggested the formation of extra energy levels in the bandgap tails, which aided the transition of electrons from the valence band to these new energy levels in the conduction band.