Structural, Electrical and Optical Properties of PVC/ZnTe Nanocomposite Thin Films

Abstract

ZnTe nanoparticles (NPs) were synthesized using hydrothermal method and then were dispersed in poly(vinyl-chloride) (PVC) to prepare hybrid PVC/ZnTe nanocomposite thin films which were deposited on glass substrates by the dip coating technique in the aim to be used in photoelectronic applications. Structural, optical and electrical properties of films were investigated by different techniques. XRD analysis revealed that synthesized ZnTe NPs have a cubic structure and a nanoscale size,while pure PVC films have a weak degree of crystallinity and exhibit a broad diffraction peak at low angles. The PVC/ZnTe nanocomposite thin films display an intense diffraction peak corresponding to the plane (220) which indicates a preferred orientation of ZnTe nanocystallites along crystallographic axis [220]. This texture was also showed by the atomic force microscopy micrographs.The analysis by FT-IR and Raman vibrational spectroscopies confirmed the incorporation of ZnTe NPs in the PVC matrix.The ZnTe/PVC nanocomposites thin films have an optical transparency over 80% in the visible range and an optical gap close to 4.07 eV. Discrepancies with respect to the gap of pure PVC (red shift) and bulk ZnTe (blue shift) are due to the effect of the interaction between the ZnTe NPs and the PVC matrixand also to the nanometric size of the ZnTe NPs. Photoluminescence (PL) spectra showed an enhanced blue emission at 466 nm,a green emissionat 522 nm and a strong red emission at 686 nm. Thus the incorporation of oriented ZnTe NPs induced a new optical behavior of the PVC polymer matrix. Electrical measurements indicate a decrease of electrical resistivity of PVC/ZnTe nanocompositesas ZnTe NPs concentration increases.