Pyroelectricity enhancement of PVDF nanocomposite thin films doped with ZnO nanoparticles

A thin film of pyroelectric composite with 0-3 connectivity was fabricated from zinc oxide (ZnO) nanopowder and polyvinylidene fluoride (PVDF) with different volume fraction from 0-0.25 wt%. The dielectric and pyroelectric properties of the samples were investigated. It was found that the presence of a small amount of ZnO nanoparticles (0.25 wt%) has significantly increased the pyroelectric coefficient of the PVDF by 25%. Furthermore, the nanocomposite films required lower poling field to form polar-d phase compared to pure PVDF thin films. Analysis of the complex permittivity in a wide range of frequency was carried out indicating that the dielectric constant and loss of PVDF/ZnO nanocomposite thin films increase when doped with ZnO. Havriliak-Negami (HN) empirical function has been employed to obtain the alpha-relaxation time of the nanocomposite thin films before and after poling. The a-relaxation time does not vary with the increase of ZnO wt%; however, the effect of poling has lengthened the relaxation time of the thin films. FTIR and XRD results supports the fact that the addition of ZnO nanoparticles into PVDF polymer thin films do not cause any significant effect on the structure of the PVDF thin films. In fact, ZnO nanoparticle has enhanced the overall pyroelectricity of PVDF by facilitating the poling process in the composites and led to phase transformation of PVDF from alpha- to delta-phase as supported by a marked reduction of (100) x-ray diffraction intensities.