Dielectric spectroscopic investigations and electrical conduction mechanism of PVDF-NiO nanocomposite thin films

摘要

Flexible material with high dielectric constant and low dielectric losses is extensively used in various areas of electronic industry. In this paper, we synthesize PVDF composite films modified with NiO to get efficient dielectric properties. Dielectric properties such as dielectric constant, dielectric loss, and AC conductivity have been measured over a wide range of frequencies (20 Hz-20 MHz) and temperature (50°C-150°C). The composite films show the maximum dielectric constant of 100 at 20 Hz for 7 wt% of NiO as compared to pure PVDF. This is due to the improved interfacial polarization at the interfaces between NiO and PVDF matrix. Modified composite films shows increase in AC conductivity with temperature at higher frequencies which can be due to the migration of charge carriers. The increase in AC conductivity is more than three orders of magnitude. The activation energy calculated from AC conductivity analysis varies from 2.93 to 0.85 at the frequency of 100 Hz. Current-voltage (Ⅰ-Ⅴ) measurements at different electric field over temperature ranges 50 °C-150°C have been used to explore the charge transport mechanism which is governed by various conduction processes like Ionic hopping, Richardson-Schottky (RS), and Poole-Frenkel (PF) model. However, the analyses suggest that the Schottky conduction mechanism is observed to be responsible for conduction in the modified PVDF films. Modified composite films with high dielectric constant and enhanced conductivity possess the broad application prospects in energy harvesting and sensing devices.