Influence of thin layer of silver nanoparticles on optical and dielectric properties of poly(vinyl alcohol) composite films

A thin interlayer of silver nanoparticles (Ag-NPs) is embedded in a matrix of poly(vinyl alcohol)(PVA)films, and its influence on the microstructural, optical, and dielectric properties of 'Ag/PVA' thin films is investigated. As evidenced from atomic force microscopy studies, size of the deposited Ag-NPs clusters and surface roughness of the films decreased with an increase of annealing temperature. Optical and structural properties of 'Ag/PVA' nanocomposites were studied using UV-Visible spectroscopy and Confocal Raman spectroscope. The PVA/Ag nanocomposite films demonstrated lower optical band gap values than pure PVA films and the estimated optical band values of 'Ag/PVA' nanocomposite films decreased from 3.66 eV to 3.57 eV with the increase of temperature from 20 °C to 200 °C, respectively. The multi-layered 'PVA/Ag-NPs/PVA' films (MLTs) were fabricated and studied their dielectric properties as a function of frequency. The presence of Ag-NPs inter layer shows significant influence on dielectric and conductivity properties of MLTs. At room temperature in comparison to pure PVA, MLTs exhibited three times higher dielectric permittivity value at 1 kHz and observed to increase 5 times with an increase in temperature to the higher value of 200 °C. The evaluated dc conductivity value of MLTs increased from −11.72 to −10.38 S/cm on a logarithmic scale with an increase in temperature from 20 °C to 200 °C, respectively.