High dielectric flexible thin films based on cellulose nanofibers and zinc sulfide nanoparticles

Abstract Nanocomposites have become potential candidate materials for integration into high-frequency electronics. In the current work, ZnS nanocomposite films were successfully prepared from cellulose nanofibers (CNF) - isolated from bagasse pulp- with different weight ratios of ZnS nanoparticles (ZnS NPs). The structure was characterized by infrared and ultraviolet–visible (UV-Vis) spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM)/ Energy dispersive X-ray spectroscopy (EDX). Infrared spectroscopy proved the presence of interactions between cellulose and ZnS nanoparticles. The SEM and EDX analysis showed that ZnS nanoparticles were well dispersed in the cellulose matrix. Band gap width of Zn/CNF nanocomposites film calculated from UV–Vis spectra was 2.64 eV which is lower than pure CNF (4.5 eV). Electrical properties were investigated within the frequency range of 100 Hz−5 MHz, and temperature range of 25–120 °C. DC- electrical conductivity was investigated and the activation energy Ea was estimated from the Arrhenius relation. The effect of wt. % of ZnS nanoparticles on electrical properties as dielectric constant, and ac-electrical conductivity (σac) were studied. The results showed that the all ZnS/CNF nanocomposite thin films had semiconductor properties and the 5 wt% ZnS NP sample had the highest conductivity value. The results indicate that the prepared flexible ZnS/ CNF nanocomposites thin films are promising candidates for semiconductor materials used in electronic devices.