Abstract
This paper presents a low-cost microwave-assisted chemical reduction method to synthesize copper nanoparticles using sodium borohydride (NaBH4) and ascorbic acid as reducing and stabilizing agents. Furthermore, the preparation of copper-doped PVA and copper-doped PVA/PVP composite films was operated using a solution casting technique. Low-cost copper nanoparticles are considered to have a broad and weak surface plasmon resonance (SPR). With the help of scanning electron microscopy (SEM) and UV–vis near-infrared spectroscopy (UV–VIS–NIR), the characterization of copper nanoparticles was analyzed. The peak of the surface plasmon resonance shifts from 240 to 300 nm. Optical characterizations of copper doped PVA and PVA/PVP composite films were established. The transmittance spectra of 1.851 wt% Cu-doped PVA and 0.590 wt% Cu-doped PVA/PVP showed light blocking in the wavelength ranges of 190–282 nm (PVA) and 289 nm (PVA/PVP). According to the absorption spectra, the surface plasmon resonance (SPR) is induced by Cu NPs at a wavelength of 260 nm. The indirect energy gap, Eg, was determined and found to decrease with an increase in the doping of Cu. Nonlinear optical properties such as nonlinear refractive index, linear optical susceptibility, and third-order nonlinear optical susceptibility were obtained. These findings will aid in producing a plasmonic novel material for optical applications.