Microstructure of Cadmium Chloride Doped PVA/PVP Blend Films

Abstract

The structural features of Cadmium Chloride (CdCl2) doped polyvinylalcohol (PVA)- Polyvinylpyrrolidone (PVP) blend films are correlated with their optical and electrical properties. Doping results in formation of self-grown nano-crystalline features; SEM images show the nano-crystals changing shape from spherical to rod-shaped structures, and with further increase in doping level flower shaped crystalline features are observed. There is formation of crystalline micro-globules (10.2 wt%) which modifies to bowl shape, and these crystalline regions disintegrate at 12.1 wt% dopant level. A homogeneous amorphous domain is observed from 15.5 wt% up to 40 wt%. AFM images, XRD patterns and DSC scans are used to complement the discussion based on SEM micrographs in order to explain the electrical and optical properties of this material at different doping levels. The electrical measurements reveal an increase in electrical resistivity at low dopant levels (from 0.5 wt% up to 5.4 wt%), and a decrease in its value on further doping, saturating beyond 15.5 wt% doping level. Optical (UV-Visible) spectra reveal formation of additional energy bands between the HOMO-LUMO levels of PVA-PVP blend films.