Optical properties of silver-dispersed PVP thin film

Silver-dispersed PVP (Ag/PVP) thin films were prepared by spin coating from an alcohol solution of polyvinylpyrrolidone (PVP) in which silver nitrate were dissolved. A peak formed at 430–450 nm in the UV/VIS-spectra resulted from the surface plasma resonance of the silver nanoparticles. With the increase of annealing temperature, the plasma resonance absorption peak was broadened and intensities increased. The peak position of the surface plasma resonance also shifted to a high wavelength. XRD results confirmed the presence of silver particles in thin films. The absorption peak position calculated from the absorption spectrum is in very good agreement with Maxwell-Garnet (MG) theory using the dielectric constant of silver particles to calculate results of the absorption coefficient, α, of the silver particles.