Structural and optical characterization of [(PVA:PVP)-Cu2+] composite films for promising semiconducting polymer devices

Abstract

High quality semiconducting polymers of copper ions doped poly(vinyl alcohol) (PVA):poly(vinyl pyrrolidone) (50:50 wt%) [(PVA:PVP)-x wt % Cu2+] [x = 0,3,5,15 and 20 wt%] composite films were successfully prepared by the conventional solution casting method. The characterizations of the films were investigated by XRD scan, FT-IR and UV–Vis–NIR spectroscopic analysis. The obtained values of the d-spacing and crystallite length D parameters from Gaussian fitting of the broad XRD peaks of the virgin PVA, [(PVA:PVP)-x wt % Cu2+] polymer composite blend films indicate the miscibility and compatibility of the blend constituents and bonding of positively charged Cu2+ ions with negatively charged OH groups of the polymer chains. The optical energy gaps and the high frequency refractive indices are strongly affected by incorporation of Cu2+ ions in the (PVA:PVP) blend chains where the optical gap decreased from 4.68 eV for pure (PVA:PVP) polymer blend to 2.95 eV for [(PVA:PVP)-20 wt % Cu2+] and the high frequency refractive index increased from 2.42 to 2.78. Based on the collected results, the copper ions doped (PVA:PVP) polymer blend composite films can be considered as a promising, new and facile material for UV filters, semiconducting polymer devices, planar polymer waveguides and polymer solar cells designing.